Add log for pruning point anticone size

* Fix a bug in the case where syncer chain is fully known to syncee

* Extract chain negotiation to a separated method

* Bump version and update the changelog

* Add zoom-in progress validation and some debug logs

* Improved error explanation

* go fmt

* Validate zoom-in progress through a total count

app/appmessage/message.go

@@ -69,6 +69,10 @@ const (
 	CmdReady
 	CmdTrustedData
 	CmdBlockWithTrustedDataV4
+	CmdRequestNextPruningPointAndItsAnticoneBlocks
+	CmdRequestIBDChainBlockLocator
+	CmdIBDChainBlockLocator
+	CmdRequestAnticone
 
 	// rpc
 	CmdGetCurrentNetworkRequestMessage
@@ -195,6 +199,10 @@ var ProtocolMessageCommandToString = map[MessageCommand]string{
 	CmdReady:                               "Ready",
 	CmdTrustedData:                         "TrustedData",
 	CmdBlockWithTrustedDataV4:              "BlockWithTrustedDataV4",
+	CmdRequestNextPruningPointAndItsAnticoneBlocks: "RequestNextPruningPointAndItsAnticoneBlocks",
+	CmdRequestIBDChainBlockLocator:                 "RequestIBDChainBlockLocator",
+	CmdIBDChainBlockLocator:                        "IBDChainBlockLocator",
+	CmdRequestAnticone:                             "RequestAnticone",
 }
 
 // RPCMessageCommandToString maps all MessageCommands to their string representation

app/appmessage/p2p_msgibdchainblocklocator.go

@@ -0,0 +1,27 @@
+package appmessage
+
+import (
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+)
+
+// MsgIBDChainBlockLocator implements the Message interface and represents a kaspa
+// locator message. It is used to find the blockLocator of a peer that is
+// syncing with you.
+type MsgIBDChainBlockLocator struct {
+	baseMessage
+	BlockLocatorHashes []*externalapi.DomainHash
+}
+
+// Command returns the protocol command string for the message. This is part
+// of the Message interface implementation.
+func (msg *MsgIBDChainBlockLocator) Command() MessageCommand {
+	return CmdIBDChainBlockLocator
+}
+
+// NewMsgIBDChainBlockLocator returns a new kaspa locator message that conforms to
+// the Message interface. See MsgBlockLocator for details.
+func NewMsgIBDChainBlockLocator(locatorHashes []*externalapi.DomainHash) *MsgIBDChainBlockLocator {
+	return &MsgIBDChainBlockLocator{
+		BlockLocatorHashes: locatorHashes,
+	}
+}

app/appmessage/p2p_msgrequestanticone.go

@@ -0,0 +1,33 @@
+// Copyright (c) 2013-2016 The btcsuite developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package appmessage
+
+import (
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+)
+
+// MsgRequestAnticone implements the Message interface and represents a kaspa
+// RequestHeaders message. It is used to request the set past(ContextHash) \cap anticone(BlockHash)
+type MsgRequestAnticone struct {
+	baseMessage
+	BlockHash   *externalapi.DomainHash
+	ContextHash *externalapi.DomainHash
+}
+
+// Command returns the protocol command string for the message. This is part
+// of the Message interface implementation.
+func (msg *MsgRequestAnticone) Command() MessageCommand {
+	return CmdRequestAnticone
+}
+
+// NewMsgRequestAnticone returns a new kaspa RequestPastDiff message that conforms to the
+// Message interface using the passed parameters and defaults for the remaining
+// fields.
+func NewMsgRequestAnticone(blockHash, contextHash *externalapi.DomainHash) *MsgRequestAnticone {
+	return &MsgRequestAnticone{
+		BlockHash:   blockHash,
+		ContextHash: contextHash,
+	}
+}

app/appmessage/p2p_msgrequestibdchainblocklocator.go

@@ -0,0 +1,31 @@
+package appmessage
+
+import (
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+)
+
+// MsgRequestIBDChainBlockLocator implements the Message interface and represents a kaspa
+// IBDRequestChainBlockLocator message. It is used to request a block locator between low
+// and high hash.
+// The locator is returned via a locator message (MsgIBDChainBlockLocator).
+type MsgRequestIBDChainBlockLocator struct {
+	baseMessage
+	HighHash *externalapi.DomainHash
+	LowHash  *externalapi.DomainHash
+}
+
+// Command returns the protocol command string for the message. This is part
+// of the Message interface implementation.
+func (msg *MsgRequestIBDChainBlockLocator) Command() MessageCommand {
+	return CmdRequestIBDChainBlockLocator
+}
+
+// NewMsgIBDRequestChainBlockLocator returns a new IBDRequestChainBlockLocator message that conforms to the
+// Message interface using the passed parameters and defaults for the remaining
+// fields.
+func NewMsgIBDRequestChainBlockLocator(highHash, lowHash *externalapi.DomainHash) *MsgRequestIBDChainBlockLocator {
+	return &MsgRequestIBDChainBlockLocator{
+		HighHash: highHash,
+		LowHash:  lowHash,
+	}
+}

app/appmessage/p2p_msgrequestnextpruningpointanditsanticoneblocks.go

@@ -0,0 +1,22 @@
+package appmessage
+
+// MsgRequestNextPruningPointAndItsAnticoneBlocks implements the Message interface and represents a kaspa
+// RequestNextPruningPointAndItsAnticoneBlocks message. It is used to notify the IBD syncer peer to send
+// more blocks from the pruning anticone.
+//
+// This message has no payload.
+type MsgRequestNextPruningPointAndItsAnticoneBlocks struct {
+	baseMessage
+}
+
+// Command returns the protocol command string for the message. This is part
+// of the Message interface implementation.
+func (msg *MsgRequestNextPruningPointAndItsAnticoneBlocks) Command() MessageCommand {
+	return CmdRequestNextPruningPointAndItsAnticoneBlocks
+}
+
+// NewMsgRequestNextPruningPointAndItsAnticoneBlocks returns a new kaspa RequestNextPruningPointAndItsAnticoneBlocks message that conforms to the
+// Message interface.
+func NewMsgRequestNextPruningPointAndItsAnticoneBlocks() *MsgRequestNextPruningPointAndItsAnticoneBlocks {
+	return &MsgRequestNextPruningPointAndItsAnticoneBlocks{}
+}

app/appmessage/rpc_submit_block.go

@@ -92,11 +92,14 @@ type RPCBlockLevelParents struct {
 
 // RPCBlockVerboseData holds verbose data about a block
 type RPCBlockVerboseData struct {
-	Hash               string
-	Difficulty         float64
-	SelectedParentHash string
-	TransactionIDs     []string
-	IsHeaderOnly       bool
-	BlueScore          uint64
-	ChildrenHashes     []string
+	Hash                string
+	Difficulty          float64
+	SelectedParentHash  string
+	TransactionIDs      []string
+	IsHeaderOnly        bool
+	BlueScore           uint64
+	ChildrenHashes      []string
+	MergeSetBluesHashes []string
+	MergeSetRedsHashes  []string
+	IsChainBlock        bool
 }

app/protocol/flowcontext/blocks.go

@@ -150,7 +150,7 @@ func (f *FlowContext) TrySetIBDRunning(ibdPeer *peerpkg.Peer) bool {
 		return false
 	}
 	f.ibdPeer = ibdPeer
-	log.Infof("IBD started")
+	log.Infof("IBD started with peer %s", ibdPeer)
 
 	return true
 }

app/protocol/flowcontext/errors.go

@@ -2,6 +2,7 @@ package flowcontext
 
 import (
 	"errors"
+	"strings"
 	"sync/atomic"
 
 	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
@@ -9,6 +10,11 @@ import (
 	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
 )
 
+var (
+	// ErrPingTimeout signifies that a ping operation timed out.
+	ErrPingTimeout = protocolerrors.New(false, "timeout expired on ping")
+)
+
 // HandleError handles an error from a flow,
 // It sends the error to errChan if isStopping == 0 and increments isStopping
 //
@@ -21,8 +27,15 @@ func (*FlowContext) HandleError(err error, flowName string, isStopping *uint32,
 		if protocolErr := (protocolerrors.ProtocolError{}); !errors.As(err, &protocolErr) {
 			panic(err)
 		}
-
-		log.Errorf("error from %s: %s", flowName, err)
+		if errors.Is(err, ErrPingTimeout) {
+			// Avoid printing the call stack on ping timeouts, since users get panicked and this case is not interesting
+			log.Errorf("error from %s: %s", flowName, err)
+		} else {
+			// Explain to the user that this is not a panic, but only a protocol error with a specific peer
+			logFrame := strings.Repeat("=", 52)
+			log.Errorf("Non-critical peer protocol error from %s, printing the full stack for debug purposes: \n%s\n%+v \n%s",
+				flowName, logFrame, err, logFrame)
+		}
 	}
 
 	if atomic.AddUint32(isStopping, 1) == 1 {

app/protocol/flows/handshake/receiveversion.go

@@ -20,7 +20,7 @@ var (
 	// connected peer may support.
 	minAcceptableProtocolVersion = uint32(4)
 
-	maxAcceptableProtocolVersion = uint32(4)
+	maxAcceptableProtocolVersion = uint32(5)
 )
 
 type receiveVersionFlow struct {

app/protocol/flows/v4/blockrelay/batch_size_test.go

@@ -0,0 +1,16 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"testing"
+)
+
+func TestIBDBatchSizeLessThanRouteCapacity(t *testing.T) {
+	// The `ibdBatchSize` constant must be equal at both syncer and syncee. Therefore, we do not want
+	// to set it to `router.DefaultMaxMessages` to avoid confusion and human errors.
+	// However, nonetheless we must enforce that it does not exceed `router.DefaultMaxMessages`
+	if ibdBatchSize > router.DefaultMaxMessages {
+		t.Fatalf("IBD batch size (%d) must be smaller than or equal to router.DefaultMaxMessages (%d)",
+			ibdBatchSize, router.DefaultMaxMessages)
+	}
+}

app/protocol/flows/v4/blockrelay/handle_ibd_block_requests.go

@@ -33,7 +33,7 @@ func HandleIBDBlockRequests(context HandleIBDBlockRequestsContext, incomingRoute
 				return err
 			}
 			if !blockInfo.Exists || blockInfo.BlockStatus == externalapi.StatusHeaderOnly {
-				return protocolerrors.Errorf(true, "block %s not found", hash)
+				return protocolerrors.Errorf(true, "block %s not found (v4)", hash)
 			}
 			block, err := context.Domain().Consensus().GetBlock(hash)
 			if err != nil {

app/protocol/flows/v4/blockrelay/handle_relay_invs.go

@@ -10,6 +10,7 @@ import (
 	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
 	"github.com/kaspanet/kaspad/domain/consensus/ruleerrors"
 	"github.com/kaspanet/kaspad/domain/consensus/utils/consensushashing"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/hashset"
 	"github.com/kaspanet/kaspad/infrastructure/config"
 	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
 	"github.com/pkg/errors"
@@ -131,6 +132,10 @@ func (flow *handleRelayInvsFlow) start() error {
 		}
 
 		log.Debugf("Processing block %s", inv.Hash)
+		oldVirtualInfo, err := flow.Domain().Consensus().GetVirtualInfo()
+		if err != nil {
+			return err
+		}
 		missingParents, virtualChangeSet, err := flow.processBlock(block)
 		if err != nil {
 			if errors.Is(err, ruleerrors.ErrPrunedBlock) {
@@ -153,11 +158,33 @@ func (flow *handleRelayInvsFlow) start() error {
 			continue
 		}
 
-		log.Debugf("Relaying block %s", inv.Hash)
-		err = flow.relayBlock(block)
+		oldVirtualParents := hashset.New()
+		for _, parent := range oldVirtualInfo.ParentHashes {
+			oldVirtualParents.Add(parent)
+		}
+
+		newVirtualInfo, err := flow.Domain().Consensus().GetVirtualInfo()
 		if err != nil {
 			return err
 		}
+
+		for _, parent := range newVirtualInfo.ParentHashes {
+			if oldVirtualParents.Contains(parent) {
+				continue
+			}
+
+			block, err := flow.Domain().Consensus().GetBlock(parent)
+			if err != nil {
+				return err
+			}
+			blockHash := consensushashing.BlockHash(block)
+			log.Debugf("Relaying block %s", blockHash)
+			err = flow.relayBlock(block)
+			if err != nil {
+				return err
+			}
+		}
+
 		log.Infof("Accepted block %s via relay", inv.Hash)
 		err = flow.OnNewBlock(block, virtualChangeSet)
 		if err != nil {
@@ -258,7 +285,10 @@ func (flow *handleRelayInvsFlow) processBlock(block *externalapi.DomainBlock) ([
 		if errors.As(err, missingParentsError) {
 			return missingParentsError.MissingParentHashes, nil, nil
 		}
-		log.Warnf("Rejected block %s from %s: %s", blockHash, flow.peer, err)
+		// A duplicate block should not appear to the user as a warning and is already reported in the calling function
+		if !errors.Is(err, ruleerrors.ErrDuplicateBlock) {
+			log.Warnf("Rejected block %s from %s: %s", blockHash, flow.peer, err)
+		}
 		return nil, nil, protocolerrors.Wrapf(true, err, "got invalid block %s from relay", blockHash)
 	}
 	return nil, virtualChangeSet, nil
@@ -369,6 +399,10 @@ func (flow *handleRelayInvsFlow) AddOrphanRootsToQueue(orphan *externalapi.Domai
 			"probably happened because it was randomly evicted immediately after it was added.", orphan)
 	}
 
+	if len(orphanRoots) == 0 {
+		// In some rare cases we get here when there are no orphan roots already
+		return nil
+	}
 	log.Infof("Block %s has %d missing ancestors. Adding them to the invs queue...", orphan, len(orphanRoots))
 
 	invMessages := make([]*appmessage.MsgInvRelayBlock, len(orphanRoots))

app/protocol/flows/v4/blockrelay/handle_request_headers.go

@@ -10,7 +10,9 @@ import (
 	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
 )
 
-const ibdBatchSize = router.DefaultMaxMessages
+// This constant must be equal at both syncer and syncee. Therefore, never (!!) change this constant unless a new p2p
+// version is introduced. See `TestIBDBatchSizeLessThanRouteCapacity` as well.
+const ibdBatchSize = 100
 
 // RequestHeadersContext is the interface for the context needed for the HandleRequestHeaders flow.
 type RequestHeadersContext interface {

app/protocol/flows/v4/blockrelay/ibd.go

@@ -13,7 +13,9 @@ import (
 	"github.com/kaspanet/kaspad/infrastructure/config"
 	"github.com/kaspanet/kaspad/infrastructure/logger"
 	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"github.com/kaspanet/kaspad/util/difficulty"
 	"github.com/pkg/errors"
+	"math/big"
 	"time"
 )
 
@@ -64,6 +66,34 @@ func (flow *handleIBDFlow) start() error {
 }
 
 func (flow *handleIBDFlow) runIBDIfNotRunning(block *externalapi.DomainBlock) error {
+	highHash := consensushashing.BlockHash(block)
+
+	// Temp code to avoid IBD from lagging nodes publishing their side-chain. This patch
+	// is applied only to p2p v4 since the implemented IBD negotiation has quadratic complexity in this worst-case.
+	// See IBD logic of p2p v5 for further details.
+	virtualSelectedParent, err := flow.Domain().Consensus().GetVirtualSelectedParent()
+	if err == nil {
+		virtualSelectedParentHeader, err := flow.Domain().Consensus().GetBlockHeader(virtualSelectedParent)
+		if err == nil {
+			// We first check that DAA score of the relay block is at distance of more than DAA window size.
+			// This indicates a side-chain which is not in the future of any block in the current virtual DAA window.
+			if virtualSelectedParentHeader.DAAScore() > block.Header.DAAScore()+2641 {
+				// We then find the 'unit' of current virtual difficulty. We check if the relay block is at least
+				// at distance of 180 such units. This signals another condition for a pow-weak side-chain.
+				virtualDifficulty := difficulty.CalcWork(virtualSelectedParentHeader.Bits())
+				var virtualSub, difficultyMul big.Int
+				if difficultyMul.Mul(virtualDifficulty, big.NewInt(180)).
+					Cmp(virtualSub.Sub(virtualSelectedParentHeader.BlueWork(), block.Header.BlueWork())) < 0 {
+					log.Criticalf("Avoiding IBD triggered by relay %s with %d DAA score diff and lower blue work (%d, %d)",
+						highHash,
+						virtualSelectedParentHeader.DAAScore()-block.Header.DAAScore(),
+						virtualSelectedParentHeader.BlueWork(), block.Header.BlueWork())
+					return nil
+				}
+			}
+		}
+	}
+
 	wasIBDNotRunning := flow.TrySetIBDRunning(flow.peer)
 	if !wasIBDNotRunning {
 		log.Debugf("IBD is already running")
@@ -76,15 +106,14 @@ func (flow *handleIBDFlow) runIBDIfNotRunning(block *externalapi.DomainBlock) er
 		flow.logIBDFinished(isFinishedSuccessfully)
 	}()
 
-	highHash := consensushashing.BlockHash(block)
-	log.Debugf("IBD started with peer %s and highHash %s", flow.peer, highHash)
-	log.Debugf("Syncing blocks up to %s", highHash)
-	log.Debugf("Trying to find highest shared chain block with peer %s with high hash %s", flow.peer, highHash)
+	log.Infof("IBD started with peer %s and highHash %s", flow.peer, highHash)
+	log.Infof("Syncing blocks up to %s", highHash)
+	log.Infof("Trying to find highest shared chain block with peer %s with high hash %s", flow.peer, highHash)
 	highestSharedBlockHash, highestSharedBlockFound, err := flow.findHighestSharedBlockHash(highHash)
 	if err != nil {
 		return err
 	}
-	log.Debugf("Found highest shared chain block %s with peer %s", highestSharedBlockHash, flow.peer)
+	log.Infof("Found highest shared chain block %s with peer %s", highestSharedBlockHash, flow.peer)
 
 	shouldDownloadHeadersProof, shouldSync, err := flow.shouldSyncAndShouldDownloadHeadersProof(block, highestSharedBlockFound)
 	if err != nil {

app/protocol/flows/v4/blockrelay/ibd_progress_reporter.go

@@ -10,6 +10,10 @@ type ibdProgressReporter struct {
 }
 
 func newIBDProgressReporter(lowDAAScore uint64, highDAAScore uint64, objectName string) *ibdProgressReporter {
+	if highDAAScore <= lowDAAScore {
+		// Avoid a zero or negative diff
+		highDAAScore = lowDAAScore + 1
+	}
 	return &ibdProgressReporter{
 		lowDAAScore:                 lowDAAScore,
 		highDAAScore:                highDAAScore,
@@ -23,7 +27,16 @@ func newIBDProgressReporter(lowDAAScore uint64, highDAAScore uint64, objectName
 func (ipr *ibdProgressReporter) reportProgress(processedDelta int, highestProcessedDAAScore uint64) {
 	ipr.processed += processedDelta
 
-	relativeDAAScore := highestProcessedDAAScore - ipr.lowDAAScore
+	// Avoid exploding numbers in the percentage report, since the original `highDAAScore` might have been only a hint
+	if highestProcessedDAAScore > ipr.highDAAScore {
+		ipr.highDAAScore = highestProcessedDAAScore + 1 // + 1 for keeping it at 99%
+		ipr.totalDAAScoreDifference = ipr.highDAAScore - ipr.lowDAAScore
+	}
+	relativeDAAScore := uint64(0)
+	if highestProcessedDAAScore > ipr.lowDAAScore {
+		// Avoid a negative diff
+		relativeDAAScore = highestProcessedDAAScore - ipr.lowDAAScore
+	}
 	progressPercent := int((float64(relativeDAAScore) / float64(ipr.totalDAAScoreDifference)) * 100)
 	if progressPercent > ipr.lastReportedProgressPercent {
 		log.Infof("IBD: Processed %d %s (%d%%)", ipr.processed, ipr.objectName, progressPercent)

app/protocol/flows/v4/blockrelay/ibd_with_headers_proof.go

@@ -24,6 +24,7 @@ func (flow *handleIBDFlow) ibdWithHeadersProof(highHash *externalapi.DomainHash,
 			return err
 		}
 
+		log.Infof("IBD with pruning proof from %s was unsuccessful. Deleting the staging consensus.", flow.peer)
 		deleteStagingConsensusErr := flow.Domain().DeleteStagingConsensus()
 		if deleteStagingConsensusErr != nil {
 			return deleteStagingConsensusErr
@@ -32,6 +33,8 @@ func (flow *handleIBDFlow) ibdWithHeadersProof(highHash *externalapi.DomainHash,
 		return err
 	}
 
+	log.Infof("Header download stage of IBD with pruning proof completed successfully from %s. "+
+		"Committing the staging consensus and deleting the previous obsolete one if such exists.", flow.peer)
 	err = flow.Domain().CommitStagingConsensus()
 	if err != nil {
 		return err
@@ -344,6 +347,7 @@ func (flow *handleIBDFlow) syncPruningPointUTXOSet(consensus externalapi.Consens
 	log.Info("Fetching the pruning point UTXO set")
 	isSuccessful, err := flow.fetchMissingUTXOSet(consensus, pruningPoint)
 	if err != nil {
+		log.Infof("An error occurred while fetching the pruning point UTXO set. Stopping IBD. (%s)", err)
 		return false, err
 	}
 

app/protocol/flows/v4/ping/send.go

@@ -2,6 +2,8 @@ package ping
 
 import (
 	"github.com/kaspanet/kaspad/app/protocol/common"
+	"github.com/kaspanet/kaspad/app/protocol/flowcontext"
+	"github.com/pkg/errors"
 	"time"
 
 	"github.com/kaspanet/kaspad/app/appmessage"
@@ -61,6 +63,9 @@ func (flow *sendPingsFlow) start() error {
 
 		message, err := flow.incomingRoute.DequeueWithTimeout(common.DefaultTimeout)
 		if err != nil {
+			if errors.Is(err, router.ErrTimeout) {
+				return errors.Wrapf(flowcontext.ErrPingTimeout, err.Error())
+			}
 			return err
 		}
 		pongMessage := message.(*appmessage.MsgPong)

app/protocol/flows/v4/transactionrelay/handle_relayed_transactions.go

@@ -22,6 +22,7 @@ type TransactionsRelayContext interface {
 	SharedRequestedTransactions() *flowcontext.SharedRequestedTransactions
 	OnTransactionAddedToMempool()
 	EnqueueTransactionIDsForPropagation(transactionIDs []*externalapi.DomainTransactionID) error
+	IsIBDRunning() bool
 }
 
 type handleRelayedTransactionsFlow struct {
@@ -49,6 +50,10 @@ func (flow *handleRelayedTransactionsFlow) start() error {
 			return err
 		}
 
+		if flow.IsIBDRunning() {
+			continue
+		}
+
 		requestedIDs, err := flow.requestInvTransactions(inv)
 		if err != nil {
 			return err

app/protocol/flows/v4/transactionrelay/handle_relayed_transactions_test.go

@@ -47,6 +47,10 @@ func (m *mocTransactionsRelayContext) EnqueueTransactionIDsForPropagation(transa
 func (m *mocTransactionsRelayContext) OnTransactionAddedToMempool() {
 }
 
+func (m *mocTransactionsRelayContext) IsIBDRunning() bool {
+	return false
+}
+
 // TestHandleRelayedTransactionsNotFound tests the flow of  HandleRelayedTransactions when the peer doesn't
 // have the requested transactions in the mempool.
 func TestHandleRelayedTransactionsNotFound(t *testing.T) {

app/protocol/flows/v5/addressexchange/receiveaddresses.go

@@ -0,0 +1,39 @@
+package addressexchange
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/common"
+	peerpkg "github.com/kaspanet/kaspad/app/protocol/peer"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/infrastructure/network/addressmanager"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+// ReceiveAddressesContext is the interface for the context needed for the ReceiveAddresses flow.
+type ReceiveAddressesContext interface {
+	AddressManager() *addressmanager.AddressManager
+}
+
+// ReceiveAddresses asks a peer for more addresses if needed.
+func ReceiveAddresses(context ReceiveAddressesContext, incomingRoute *router.Route, outgoingRoute *router.Route,
+	peer *peerpkg.Peer) error {
+
+	subnetworkID := peer.SubnetworkID()
+	msgGetAddresses := appmessage.NewMsgRequestAddresses(false, subnetworkID)
+	err := outgoingRoute.Enqueue(msgGetAddresses)
+	if err != nil {
+		return err
+	}
+
+	message, err := incomingRoute.DequeueWithTimeout(common.DefaultTimeout)
+	if err != nil {
+		return err
+	}
+
+	msgAddresses := message.(*appmessage.MsgAddresses)
+	if len(msgAddresses.AddressList) > addressmanager.GetAddressesMax {
+		return protocolerrors.Errorf(true, "address count exceeded %d", addressmanager.GetAddressesMax)
+	}
+
+	return context.AddressManager().AddAddresses(msgAddresses.AddressList...)
+}

app/protocol/flows/v5/addressexchange/sendaddresses.go

@@ -0,0 +1,52 @@
+package addressexchange
+
+import (
+	"math/rand"
+
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/infrastructure/network/addressmanager"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+// SendAddressesContext is the interface for the context needed for the SendAddresses flow.
+type SendAddressesContext interface {
+	AddressManager() *addressmanager.AddressManager
+}
+
+// SendAddresses sends addresses to a peer that requests it.
+func SendAddresses(context SendAddressesContext, incomingRoute *router.Route, outgoingRoute *router.Route) error {
+	for {
+		_, err := incomingRoute.Dequeue()
+		if err != nil {
+			return err
+		}
+
+		addresses := context.AddressManager().Addresses()
+		msgAddresses := appmessage.NewMsgAddresses(shuffleAddresses(addresses))
+
+		err = outgoingRoute.Enqueue(msgAddresses)
+		if err != nil {
+			return err
+		}
+	}
+}
+
+// shuffleAddresses randomizes the given addresses sent if there are more than the maximum allowed in one message.
+func shuffleAddresses(addresses []*appmessage.NetAddress) []*appmessage.NetAddress {
+	addressCount := len(addresses)
+
+	if addressCount < appmessage.MaxAddressesPerMsg {
+		return addresses
+	}
+
+	shuffleAddresses := make([]*appmessage.NetAddress, addressCount)
+	copy(shuffleAddresses, addresses)
+
+	rand.Shuffle(addressCount, func(i, j int) {
+		shuffleAddresses[i], shuffleAddresses[j] = shuffleAddresses[j], shuffleAddresses[i]
+	})
+
+	// Truncate it to the maximum size.
+	shuffleAddresses = shuffleAddresses[:appmessage.MaxAddressesPerMsg]
+	return shuffleAddresses
+}

app/protocol/flows/v5/blockrelay/batch_size_test.go

@@ -0,0 +1,16 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"testing"
+)
+
+func TestIBDBatchSizeLessThanRouteCapacity(t *testing.T) {
+	// The `ibdBatchSize` constant must be equal at both syncer and syncee. Therefore, we do not want
+	// to set it to `router.DefaultMaxMessages` to avoid confusion and human errors.
+	// However, nonetheless we must enforce that it does not exceed `router.DefaultMaxMessages`
+	if ibdBatchSize >= router.DefaultMaxMessages {
+		t.Fatalf("IBD batch size (%d) must be smaller than router.DefaultMaxMessages (%d)",
+			ibdBatchSize, router.DefaultMaxMessages)
+	}
+}

app/protocol/flows/v5/blockrelay/block_locator.go

@@ -0,0 +1,33 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/common"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+)
+
+func (flow *handleRelayInvsFlow) sendGetBlockLocator(highHash *externalapi.DomainHash, limit uint32) error {
+	msgGetBlockLocator := appmessage.NewMsgRequestBlockLocator(highHash, limit)
+	return flow.outgoingRoute.Enqueue(msgGetBlockLocator)
+}
+
+func (flow *handleRelayInvsFlow) receiveBlockLocator() (blockLocatorHashes []*externalapi.DomainHash, err error) {
+	for {
+		message, err := flow.incomingRoute.DequeueWithTimeout(common.DefaultTimeout)
+		if err != nil {
+			return nil, err
+		}
+
+		switch message := message.(type) {
+		case *appmessage.MsgInvRelayBlock:
+			flow.invsQueue = append(flow.invsQueue, message)
+		case *appmessage.MsgBlockLocator:
+			return message.BlockLocatorHashes, nil
+		default:
+			return nil,
+				protocolerrors.Errorf(true, "received unexpected message type. "+
+					"expected: %s, got: %s", appmessage.CmdBlockLocator, message.Command())
+		}
+	}
+}

app/protocol/flows/v5/blockrelay/handle_ibd_block_locator.go

@@ -0,0 +1,86 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/peer"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+// HandleIBDBlockLocatorContext is the interface for the context needed for the HandleIBDBlockLocator flow.
+type HandleIBDBlockLocatorContext interface {
+	Domain() domain.Domain
+}
+
+// HandleIBDBlockLocator listens to appmessage.MsgIBDBlockLocator messages and sends
+// the highest known block that's in the selected parent chain of `targetHash` to the
+// requesting peer.
+func HandleIBDBlockLocator(context HandleIBDBlockLocatorContext, incomingRoute *router.Route,
+	outgoingRoute *router.Route, peer *peer.Peer) error {
+
+	for {
+		message, err := incomingRoute.Dequeue()
+		if err != nil {
+			return err
+		}
+		ibdBlockLocatorMessage := message.(*appmessage.MsgIBDBlockLocator)
+
+		targetHash := ibdBlockLocatorMessage.TargetHash
+		log.Debugf("Received IBDBlockLocator from %s with targetHash %s", peer, targetHash)
+
+		blockInfo, err := context.Domain().Consensus().GetBlockInfo(targetHash)
+		if err != nil {
+			return err
+		}
+		if !blockInfo.Exists {
+			return protocolerrors.Errorf(true, "received IBDBlockLocator "+
+				"with an unknown targetHash %s", targetHash)
+		}
+
+		foundHighestHashInTheSelectedParentChainOfTargetHash := false
+		for _, blockLocatorHash := range ibdBlockLocatorMessage.BlockLocatorHashes {
+			blockInfo, err := context.Domain().Consensus().GetBlockInfo(blockLocatorHash)
+			if err != nil {
+				return err
+			}
+
+			// The IBD block locator is checking only existing blocks with bodies.
+			if !blockInfo.Exists || blockInfo.BlockStatus == externalapi.StatusHeaderOnly {
+				continue
+			}
+
+			isBlockLocatorHashInSelectedParentChainOfHighHash, err :=
+				context.Domain().Consensus().IsInSelectedParentChainOf(blockLocatorHash, targetHash)
+			if err != nil {
+				return err
+			}
+			if !isBlockLocatorHashInSelectedParentChainOfHighHash {
+				continue
+			}
+
+			foundHighestHashInTheSelectedParentChainOfTargetHash = true
+			log.Debugf("Found a known hash %s amongst peer %s's "+
+				"blockLocator that's in the selected parent chain of targetHash %s", blockLocatorHash, peer, targetHash)
+
+			ibdBlockLocatorHighestHashMessage := appmessage.NewMsgIBDBlockLocatorHighestHash(blockLocatorHash)
+			err = outgoingRoute.Enqueue(ibdBlockLocatorHighestHashMessage)
+			if err != nil {
+				return err
+			}
+			break
+		}
+
+		if !foundHighestHashInTheSelectedParentChainOfTargetHash {
+			log.Warnf("no hash was found in the blockLocator "+
+				"that was in the selected parent chain of targetHash %s", targetHash)
+
+			ibdBlockLocatorHighestHashNotFoundMessage := appmessage.NewMsgIBDBlockLocatorHighestHashNotFound()
+			err = outgoingRoute.Enqueue(ibdBlockLocatorHighestHashNotFoundMessage)
+			if err != nil {
+				return err
+			}
+		}
+	}
+}

app/protocol/flows/v5/blockrelay/handle_ibd_block_requests.go

@@ -0,0 +1,54 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"github.com/pkg/errors"
+)
+
+// HandleIBDBlockRequestsContext is the interface for the context needed for the HandleIBDBlockRequests flow.
+type HandleIBDBlockRequestsContext interface {
+	Domain() domain.Domain
+}
+
+// HandleIBDBlockRequests listens to appmessage.MsgRequestRelayBlocks messages and sends
+// their corresponding blocks to the requesting peer.
+func HandleIBDBlockRequests(context HandleIBDBlockRequestsContext, incomingRoute *router.Route,
+	outgoingRoute *router.Route) error {
+
+	for {
+		message, err := incomingRoute.Dequeue()
+		if err != nil {
+			return err
+		}
+		msgRequestIBDBlocks := message.(*appmessage.MsgRequestIBDBlocks)
+		log.Debugf("Got request for %d ibd blocks", len(msgRequestIBDBlocks.Hashes))
+		for i, hash := range msgRequestIBDBlocks.Hashes {
+			// Fetch the block from the database.
+			blockInfo, err := context.Domain().Consensus().GetBlockInfo(hash)
+			if err != nil {
+				return err
+			}
+			if !blockInfo.Exists || blockInfo.BlockStatus == externalapi.StatusHeaderOnly {
+				return protocolerrors.Errorf(true, "block %s not found (v5)", hash)
+			}
+			block, err := context.Domain().Consensus().GetBlock(hash)
+			if err != nil {
+				return errors.Wrapf(err, "unable to fetch requested block hash %s", hash)
+			}
+
+			// TODO (Partial nodes): Convert block to partial block if needed
+
+			blockMessage := appmessage.DomainBlockToMsgBlock(block)
+			ibdBlockMessage := appmessage.NewMsgIBDBlock(blockMessage)
+			err = outgoingRoute.Enqueue(ibdBlockMessage)
+			if err != nil {
+				return err
+			}
+			log.Debugf("sent %d out of %d", i+1, len(msgRequestIBDBlocks.Hashes))
+		}
+	}
+}

app/protocol/flows/v5/blockrelay/handle_ibd_request_chain_block_locator.go

@@ -0,0 +1,85 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/domain/consensus/model"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"github.com/pkg/errors"
+)
+
+// RequestIBDChainBlockLocatorContext is the interface for the context needed for the HandleRequestBlockLocator flow.
+type RequestIBDChainBlockLocatorContext interface {
+	Domain() domain.Domain
+}
+
+type handleRequestIBDChainBlockLocatorFlow struct {
+	RequestIBDChainBlockLocatorContext
+	incomingRoute, outgoingRoute *router.Route
+}
+
+// HandleRequestIBDChainBlockLocator handles getBlockLocator messages
+func HandleRequestIBDChainBlockLocator(context RequestIBDChainBlockLocatorContext, incomingRoute *router.Route,
+	outgoingRoute *router.Route) error {
+
+	flow := &handleRequestIBDChainBlockLocatorFlow{
+		RequestIBDChainBlockLocatorContext: context,
+		incomingRoute:                      incomingRoute,
+		outgoingRoute:                      outgoingRoute,
+	}
+	return flow.start()
+}
+
+func (flow *handleRequestIBDChainBlockLocatorFlow) start() error {
+	for {
+		highHash, lowHash, err := flow.receiveRequestIBDChainBlockLocator()
+		if err != nil {
+			return err
+		}
+		log.Debugf("Received getIBDChainBlockLocator with highHash: %s, lowHash: %s", highHash, lowHash)
+
+		var locator externalapi.BlockLocator
+		if highHash == nil || lowHash == nil {
+			locator, err = flow.Domain().Consensus().CreateFullHeadersSelectedChainBlockLocator()
+		} else {
+			locator, err = flow.Domain().Consensus().CreateHeadersSelectedChainBlockLocator(lowHash, highHash)
+			if errors.Is(model.ErrBlockNotInSelectedParentChain, err) {
+				// The chain has been modified, signal it by sending an empty locator
+				locator, err = externalapi.BlockLocator{}, nil
+			}
+		}
+
+		if err != nil {
+			log.Debugf("Received error from CreateHeadersSelectedChainBlockLocator: %s", err)
+			return protocolerrors.Errorf(true, "couldn't build a block "+
+				"locator between %s and %s", lowHash, highHash)
+		}
+
+		err = flow.sendIBDChainBlockLocator(locator)
+		if err != nil {
+			return err
+		}
+	}
+}
+
+func (flow *handleRequestIBDChainBlockLocatorFlow) receiveRequestIBDChainBlockLocator() (highHash, lowHash *externalapi.DomainHash, err error) {
+
+	message, err := flow.incomingRoute.Dequeue()
+	if err != nil {
+		return nil, nil, err
+	}
+	msgGetBlockLocator := message.(*appmessage.MsgRequestIBDChainBlockLocator)
+
+	return msgGetBlockLocator.HighHash, msgGetBlockLocator.LowHash, nil
+}
+
+func (flow *handleRequestIBDChainBlockLocatorFlow) sendIBDChainBlockLocator(locator externalapi.BlockLocator) error {
+	msgIBDChainBlockLocator := appmessage.NewMsgIBDChainBlockLocator(locator)
+	err := flow.outgoingRoute.Enqueue(msgIBDChainBlockLocator)
+	if err != nil {
+		return err
+	}
+	return nil
+}

app/protocol/flows/v5/blockrelay/handle_pruning_point_and_its_anticone_requests.go

@@ -0,0 +1,160 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	peerpkg "github.com/kaspanet/kaspad/app/protocol/peer"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/infrastructure/config"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"sync/atomic"
+)
+
+// PruningPointAndItsAnticoneRequestsContext is the interface for the context needed for the HandlePruningPointAndItsAnticoneRequests flow.
+type PruningPointAndItsAnticoneRequestsContext interface {
+	Domain() domain.Domain
+	Config() *config.Config
+}
+
+var isBusy uint32
+
+// HandlePruningPointAndItsAnticoneRequests listens to appmessage.MsgRequestPruningPointAndItsAnticone messages and sends
+// the pruning point and its anticone to the requesting peer.
+func HandlePruningPointAndItsAnticoneRequests(context PruningPointAndItsAnticoneRequestsContext, incomingRoute *router.Route,
+	outgoingRoute *router.Route, peer *peerpkg.Peer) error {
+
+	for {
+		err := func() error {
+			_, err := incomingRoute.Dequeue()
+			if err != nil {
+				return err
+			}
+
+			if !atomic.CompareAndSwapUint32(&isBusy, 0, 1) {
+				return protocolerrors.Errorf(false, "node is busy with other pruning point anticone requests")
+			}
+			defer atomic.StoreUint32(&isBusy, 0)
+
+			log.Debugf("Got request for pruning point and its anticone from %s", peer)
+
+			pruningPointHeaders, err := context.Domain().Consensus().PruningPointHeaders()
+			if err != nil {
+				return err
+			}
+
+			log.Criticalf("Pruning point anticone size is %d", len(pruningPointHeaders))
+
+			msgPruningPointHeaders := make([]*appmessage.MsgBlockHeader, len(pruningPointHeaders))
+			for i, header := range pruningPointHeaders {
+				msgPruningPointHeaders[i] = appmessage.DomainBlockHeaderToBlockHeader(header)
+			}
+
+			err = outgoingRoute.Enqueue(appmessage.NewMsgPruningPoints(msgPruningPointHeaders))
+			if err != nil {
+				return err
+			}
+
+			pointAndItsAnticone, err := context.Domain().Consensus().PruningPointAndItsAnticone()
+			if err != nil {
+				return err
+			}
+
+			windowSize := context.Config().NetParams().DifficultyAdjustmentWindowSize
+			daaWindowBlocks := make([]*externalapi.TrustedDataDataDAAHeader, 0, windowSize)
+			daaWindowHashesToIndex := make(map[externalapi.DomainHash]int, windowSize)
+			trustedDataDAABlockIndexes := make(map[externalapi.DomainHash][]uint64)
+
+			ghostdagData := make([]*externalapi.BlockGHOSTDAGDataHashPair, 0)
+			ghostdagDataHashToIndex := make(map[externalapi.DomainHash]int)
+			trustedDataGHOSTDAGDataIndexes := make(map[externalapi.DomainHash][]uint64)
+			for _, blockHash := range pointAndItsAnticone {
+				blockDAAWindowHashes, err := context.Domain().Consensus().BlockDAAWindowHashes(blockHash)
+				if err != nil {
+					return err
+				}
+
+				trustedDataDAABlockIndexes[*blockHash] = make([]uint64, 0, windowSize)
+				for i, daaBlockHash := range blockDAAWindowHashes {
+					index, exists := daaWindowHashesToIndex[*daaBlockHash]
+					if !exists {
+						trustedDataDataDAAHeader, err := context.Domain().Consensus().TrustedDataDataDAAHeader(blockHash, daaBlockHash, uint64(i))
+						if err != nil {
+							return err
+						}
+						daaWindowBlocks = append(daaWindowBlocks, trustedDataDataDAAHeader)
+						index = len(daaWindowBlocks) - 1
+						daaWindowHashesToIndex[*daaBlockHash] = index
+					}
+
+					trustedDataDAABlockIndexes[*blockHash] = append(trustedDataDAABlockIndexes[*blockHash], uint64(index))
+				}
+
+				ghostdagDataBlockHashes, err := context.Domain().Consensus().TrustedBlockAssociatedGHOSTDAGDataBlockHashes(blockHash)
+				if err != nil {
+					return err
+				}
+
+				trustedDataGHOSTDAGDataIndexes[*blockHash] = make([]uint64, 0, context.Config().NetParams().K)
+				for _, ghostdagDataBlockHash := range ghostdagDataBlockHashes {
+					index, exists := ghostdagDataHashToIndex[*ghostdagDataBlockHash]
+					if !exists {
+						data, err := context.Domain().Consensus().TrustedGHOSTDAGData(ghostdagDataBlockHash)
+						if err != nil {
+							return err
+						}
+						ghostdagData = append(ghostdagData, &externalapi.BlockGHOSTDAGDataHashPair{
+							Hash:         ghostdagDataBlockHash,
+							GHOSTDAGData: data,
+						})
+						index = len(ghostdagData) - 1
+						ghostdagDataHashToIndex[*ghostdagDataBlockHash] = index
+					}
+
+					trustedDataGHOSTDAGDataIndexes[*blockHash] = append(trustedDataGHOSTDAGDataIndexes[*blockHash], uint64(index))
+				}
+			}
+
+			err = outgoingRoute.Enqueue(appmessage.DomainTrustedDataToTrustedData(daaWindowBlocks, ghostdagData))
+			if err != nil {
+				return err
+			}
+
+			for i, blockHash := range pointAndItsAnticone {
+				block, err := context.Domain().Consensus().GetBlock(blockHash)
+				if err != nil {
+					return err
+				}
+
+				err = outgoingRoute.Enqueue(appmessage.DomainBlockWithTrustedDataToBlockWithTrustedDataV4(block, trustedDataDAABlockIndexes[*blockHash], trustedDataGHOSTDAGDataIndexes[*blockHash]))
+				if err != nil {
+					return err
+				}
+
+				if (i+1)%ibdBatchSize == 0 {
+					// No timeout here, as we don't care if the syncee takes its time computing,
+					// since it only blocks this dedicated flow
+					message, err := incomingRoute.Dequeue()
+					if err != nil {
+						return err
+					}
+					if _, ok := message.(*appmessage.MsgRequestNextPruningPointAndItsAnticoneBlocks); !ok {
+						return protocolerrors.Errorf(true, "received unexpected message type. "+
+							"expected: %s, got: %s", appmessage.CmdRequestNextPruningPointAndItsAnticoneBlocks, message.Command())
+					}
+				}
+			}
+
+			err = outgoingRoute.Enqueue(appmessage.NewMsgDoneBlocksWithTrustedData())
+			if err != nil {
+				return err
+			}
+
+			log.Debugf("Sent pruning point and its anticone to %s", peer)
+			return nil
+		}()
+		if err != nil {
+			return err
+		}
+	}
+}

app/protocol/flows/v5/blockrelay/handle_pruning_point_proof_requests.go

@@ -0,0 +1,40 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	peerpkg "github.com/kaspanet/kaspad/app/protocol/peer"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+// PruningPointProofRequestsContext is the interface for the context needed for the HandlePruningPointProofRequests flow.
+type PruningPointProofRequestsContext interface {
+	Domain() domain.Domain
+}
+
+// HandlePruningPointProofRequests listens to appmessage.MsgRequestPruningPointProof messages and sends
+// the pruning point proof to the requesting peer.
+func HandlePruningPointProofRequests(context PruningPointProofRequestsContext, incomingRoute *router.Route,
+	outgoingRoute *router.Route, peer *peerpkg.Peer) error {
+
+	for {
+		_, err := incomingRoute.Dequeue()
+		if err != nil {
+			return err
+		}
+
+		log.Debugf("Got request for pruning point proof from %s", peer)
+
+		pruningPointProof, err := context.Domain().Consensus().BuildPruningPointProof()
+		if err != nil {
+			return err
+		}
+		pruningPointProofMessage := appmessage.DomainPruningPointProofToMsgPruningPointProof(pruningPointProof)
+		err = outgoingRoute.Enqueue(pruningPointProofMessage)
+		if err != nil {
+			return err
+		}
+
+		log.Debugf("Sent pruning point proof to %s", peer)
+	}
+}

app/protocol/flows/v5/blockrelay/handle_relay_block_requests.go

@@ -0,0 +1,53 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	peerpkg "github.com/kaspanet/kaspad/app/protocol/peer"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"github.com/pkg/errors"
+)
+
+// RelayBlockRequestsContext is the interface for the context needed for the HandleRelayBlockRequests flow.
+type RelayBlockRequestsContext interface {
+	Domain() domain.Domain
+}
+
+// HandleRelayBlockRequests listens to appmessage.MsgRequestRelayBlocks messages and sends
+// their corresponding blocks to the requesting peer.
+func HandleRelayBlockRequests(context RelayBlockRequestsContext, incomingRoute *router.Route,
+	outgoingRoute *router.Route, peer *peerpkg.Peer) error {
+
+	for {
+		message, err := incomingRoute.Dequeue()
+		if err != nil {
+			return err
+		}
+		getRelayBlocksMessage := message.(*appmessage.MsgRequestRelayBlocks)
+		log.Debugf("Got request for relay blocks with hashes %s", getRelayBlocksMessage.Hashes)
+		for _, hash := range getRelayBlocksMessage.Hashes {
+			// Fetch the block from the database.
+			blockInfo, err := context.Domain().Consensus().GetBlockInfo(hash)
+			if err != nil {
+				return err
+			}
+			if !blockInfo.Exists || blockInfo.BlockStatus == externalapi.StatusHeaderOnly {
+				return protocolerrors.Errorf(true, "block %s not found", hash)
+			}
+			block, err := context.Domain().Consensus().GetBlock(hash)
+			if err != nil {
+				return errors.Wrapf(err, "unable to fetch requested block hash %s", hash)
+			}
+
+			// TODO (Partial nodes): Convert block to partial block if needed
+
+			err = outgoingRoute.Enqueue(appmessage.DomainBlockToMsgBlock(block))
+			if err != nil {
+				return err
+			}
+			log.Debugf("Relayed block with hash %s", hash)
+		}
+	}
+}

app/protocol/flows/v5/blockrelay/handle_relay_invs.go

@@ -0,0 +1,416 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/common"
+	"github.com/kaspanet/kaspad/app/protocol/flowcontext"
+	peerpkg "github.com/kaspanet/kaspad/app/protocol/peer"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/domain/consensus/ruleerrors"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/consensushashing"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/hashset"
+	"github.com/kaspanet/kaspad/infrastructure/config"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"github.com/pkg/errors"
+)
+
+// orphanResolutionRange is the maximum amount of blockLocator hashes
+// to search for known blocks. See isBlockInOrphanResolutionRange for
+// further details
+var orphanResolutionRange uint32 = 5
+
+// RelayInvsContext is the interface for the context needed for the HandleRelayInvs flow.
+type RelayInvsContext interface {
+	Domain() domain.Domain
+	Config() *config.Config
+	OnNewBlock(block *externalapi.DomainBlock, virtualChangeSet *externalapi.VirtualChangeSet) error
+	OnVirtualChange(virtualChangeSet *externalapi.VirtualChangeSet) error
+	OnPruningPointUTXOSetOverride() error
+	SharedRequestedBlocks() *flowcontext.SharedRequestedBlocks
+	Broadcast(message appmessage.Message) error
+	AddOrphan(orphanBlock *externalapi.DomainBlock)
+	GetOrphanRoots(orphanHash *externalapi.DomainHash) ([]*externalapi.DomainHash, bool, error)
+	IsOrphan(blockHash *externalapi.DomainHash) bool
+	IsIBDRunning() bool
+	IsRecoverableError(err error) bool
+}
+
+type handleRelayInvsFlow struct {
+	RelayInvsContext
+	incomingRoute, outgoingRoute *router.Route
+	peer                         *peerpkg.Peer
+	invsQueue                    []*appmessage.MsgInvRelayBlock
+}
+
+// HandleRelayInvs listens to appmessage.MsgInvRelayBlock messages, requests their corresponding blocks if they
+// are missing, adds them to the DAG and propagates them to the rest of the network.
+func HandleRelayInvs(context RelayInvsContext, incomingRoute *router.Route, outgoingRoute *router.Route,
+	peer *peerpkg.Peer) error {
+
+	flow := &handleRelayInvsFlow{
+		RelayInvsContext: context,
+		incomingRoute:    incomingRoute,
+		outgoingRoute:    outgoingRoute,
+		peer:             peer,
+		invsQueue:        make([]*appmessage.MsgInvRelayBlock, 0),
+	}
+	err := flow.start()
+	// Currently, HandleRelayInvs flow is the only place where IBD is triggered, so the channel can be closed now
+	close(peer.IBDRequestChannel())
+	return err
+}
+
+func (flow *handleRelayInvsFlow) start() error {
+	for {
+		log.Debugf("Waiting for inv")
+		inv, err := flow.readInv()
+		if err != nil {
+			return err
+		}
+
+		log.Debugf("Got relay inv for block %s", inv.Hash)
+
+		blockInfo, err := flow.Domain().Consensus().GetBlockInfo(inv.Hash)
+		if err != nil {
+			return err
+		}
+		if blockInfo.Exists && blockInfo.BlockStatus != externalapi.StatusHeaderOnly {
+			if blockInfo.BlockStatus == externalapi.StatusInvalid {
+				return protocolerrors.Errorf(true, "sent inv of an invalid block %s",
+					inv.Hash)
+			}
+			log.Debugf("Block %s already exists. continuing...", inv.Hash)
+			continue
+		}
+
+		isGenesisVirtualSelectedParent, err := flow.isGenesisVirtualSelectedParent()
+		if err != nil {
+			return err
+		}
+
+		if flow.IsOrphan(inv.Hash) {
+			if flow.Config().NetParams().DisallowDirectBlocksOnTopOfGenesis && !flow.Config().AllowSubmitBlockWhenNotSynced && isGenesisVirtualSelectedParent {
+				log.Infof("Cannot process orphan %s for a node with only the genesis block. The node needs to IBD "+
+					"to the recent pruning point before normal operation can resume.", inv.Hash)
+				continue
+			}
+
+			log.Debugf("Block %s is a known orphan. Requesting its missing ancestors", inv.Hash)
+			err := flow.AddOrphanRootsToQueue(inv.Hash)
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
+		// Block relay is disabled during IBD
+		if flow.IsIBDRunning() {
+			log.Debugf("Got block %s while in IBD. continuing...", inv.Hash)
+			continue
+		}
+
+		log.Debugf("Requesting block %s", inv.Hash)
+		block, exists, err := flow.requestBlock(inv.Hash)
+		if err != nil {
+			return err
+		}
+		if exists {
+			log.Debugf("Aborting requesting block %s because it already exists", inv.Hash)
+			continue
+		}
+
+		err = flow.banIfBlockIsHeaderOnly(block)
+		if err != nil {
+			return err
+		}
+
+		if flow.Config().NetParams().DisallowDirectBlocksOnTopOfGenesis && !flow.Config().AllowSubmitBlockWhenNotSynced && !flow.Config().Devnet && flow.isChildOfGenesis(block) {
+			log.Infof("Cannot process %s because it's a direct child of genesis.", consensushashing.BlockHash(block))
+			continue
+		}
+
+		log.Debugf("Processing block %s", inv.Hash)
+		oldVirtualInfo, err := flow.Domain().Consensus().GetVirtualInfo()
+		if err != nil {
+			return err
+		}
+		missingParents, virtualChangeSet, err := flow.processBlock(block)
+		if err != nil {
+			if errors.Is(err, ruleerrors.ErrPrunedBlock) {
+				log.Infof("Ignoring pruned block %s", inv.Hash)
+				continue
+			}
+
+			if errors.Is(err, ruleerrors.ErrDuplicateBlock) {
+				log.Infof("Ignoring duplicate block %s", inv.Hash)
+				continue
+			}
+			return err
+		}
+		if len(missingParents) > 0 {
+			log.Debugf("Block %s is orphan and has missing parents: %s", inv.Hash, missingParents)
+			err := flow.processOrphan(block)
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
+		oldVirtualParents := hashset.New()
+		for _, parent := range oldVirtualInfo.ParentHashes {
+			oldVirtualParents.Add(parent)
+		}
+
+		newVirtualInfo, err := flow.Domain().Consensus().GetVirtualInfo()
+		if err != nil {
+			return err
+		}
+
+		for _, parent := range newVirtualInfo.ParentHashes {
+			if oldVirtualParents.Contains(parent) {
+				continue
+			}
+
+			block, err := flow.Domain().Consensus().GetBlock(parent)
+			if err != nil {
+				return err
+			}
+			blockHash := consensushashing.BlockHash(block)
+			log.Debugf("Relaying block %s", blockHash)
+			err = flow.relayBlock(block)
+			if err != nil {
+				return err
+			}
+		}
+
+		log.Infof("Accepted block %s via relay", inv.Hash)
+		err = flow.OnNewBlock(block, virtualChangeSet)
+		if err != nil {
+			return err
+		}
+	}
+}
+
+func (flow *handleRelayInvsFlow) banIfBlockIsHeaderOnly(block *externalapi.DomainBlock) error {
+	if len(block.Transactions) == 0 {
+		return protocolerrors.Errorf(true, "sent header of %s block where expected block with body",
+			consensushashing.BlockHash(block))
+	}
+
+	return nil
+}
+
+func (flow *handleRelayInvsFlow) readInv() (*appmessage.MsgInvRelayBlock, error) {
+	if len(flow.invsQueue) > 0 {
+		var inv *appmessage.MsgInvRelayBlock
+		inv, flow.invsQueue = flow.invsQueue[0], flow.invsQueue[1:]
+		return inv, nil
+	}
+
+	msg, err := flow.incomingRoute.Dequeue()
+	if err != nil {
+		return nil, err
+	}
+
+	inv, ok := msg.(*appmessage.MsgInvRelayBlock)
+	if !ok {
+		return nil, protocolerrors.Errorf(true, "unexpected %s message in the block relay handleRelayInvsFlow while "+
+			"expecting an inv message", msg.Command())
+	}
+	return inv, nil
+}
+
+func (flow *handleRelayInvsFlow) requestBlock(requestHash *externalapi.DomainHash) (*externalapi.DomainBlock, bool, error) {
+	exists := flow.SharedRequestedBlocks().AddIfNotExists(requestHash)
+	if exists {
+		return nil, true, nil
+	}
+
+	// In case the function returns earlier than expected, we want to make sure flow.SharedRequestedBlocks() is
+	// clean from any pending blocks.
+	defer flow.SharedRequestedBlocks().Remove(requestHash)
+
+	getRelayBlocksMsg := appmessage.NewMsgRequestRelayBlocks([]*externalapi.DomainHash{requestHash})
+	err := flow.outgoingRoute.Enqueue(getRelayBlocksMsg)
+	if err != nil {
+		return nil, false, err
+	}
+
+	msgBlock, err := flow.readMsgBlock()
+	if err != nil {
+		return nil, false, err
+	}
+
+	block := appmessage.MsgBlockToDomainBlock(msgBlock)
+	blockHash := consensushashing.BlockHash(block)
+	if !blockHash.Equal(requestHash) {
+		return nil, false, protocolerrors.Errorf(true, "got unrequested block %s", blockHash)
+	}
+
+	return block, false, nil
+}
+
+// readMsgBlock returns the next msgBlock in msgChan, and populates invsQueue with any inv messages that meanwhile arrive.
+//
+// Note: this function assumes msgChan can contain only appmessage.MsgInvRelayBlock and appmessage.MsgBlock messages.
+func (flow *handleRelayInvsFlow) readMsgBlock() (msgBlock *appmessage.MsgBlock, err error) {
+	for {
+		message, err := flow.incomingRoute.DequeueWithTimeout(common.DefaultTimeout)
+		if err != nil {
+			return nil, err
+		}
+
+		switch message := message.(type) {
+		case *appmessage.MsgInvRelayBlock:
+			flow.invsQueue = append(flow.invsQueue, message)
+		case *appmessage.MsgBlock:
+			return message, nil
+		default:
+			return nil, errors.Errorf("unexpected message %s", message.Command())
+		}
+	}
+}
+
+func (flow *handleRelayInvsFlow) processBlock(block *externalapi.DomainBlock) ([]*externalapi.DomainHash, *externalapi.VirtualChangeSet, error) {
+	blockHash := consensushashing.BlockHash(block)
+	virtualChangeSet, err := flow.Domain().Consensus().ValidateAndInsertBlock(block, true)
+	if err != nil {
+		if !errors.As(err, &ruleerrors.RuleError{}) {
+			return nil, nil, errors.Wrapf(err, "failed to process block %s", blockHash)
+		}
+
+		missingParentsError := &ruleerrors.ErrMissingParents{}
+		if errors.As(err, missingParentsError) {
+			return missingParentsError.MissingParentHashes, nil, nil
+		}
+		// A duplicate block should not appear to the user as a warning and is already reported in the calling function
+		if !errors.Is(err, ruleerrors.ErrDuplicateBlock) {
+			log.Warnf("Rejected block %s from %s: %s", blockHash, flow.peer, err)
+		}
+		return nil, nil, protocolerrors.Wrapf(true, err, "got invalid block %s from relay", blockHash)
+	}
+	return nil, virtualChangeSet, nil
+}
+
+func (flow *handleRelayInvsFlow) relayBlock(block *externalapi.DomainBlock) error {
+	blockHash := consensushashing.BlockHash(block)
+	return flow.Broadcast(appmessage.NewMsgInvBlock(blockHash))
+}
+
+func (flow *handleRelayInvsFlow) processOrphan(block *externalapi.DomainBlock) error {
+	blockHash := consensushashing.BlockHash(block)
+
+	// Return if the block has been orphaned from elsewhere already
+	if flow.IsOrphan(blockHash) {
+		log.Debugf("Skipping orphan processing for block %s because it is already an orphan", blockHash)
+		return nil
+	}
+
+	// Add the block to the orphan set if it's within orphan resolution range
+	isBlockInOrphanResolutionRange, err := flow.isBlockInOrphanResolutionRange(blockHash)
+	if err != nil {
+		return err
+	}
+	if isBlockInOrphanResolutionRange {
+		if flow.Config().NetParams().DisallowDirectBlocksOnTopOfGenesis && !flow.Config().AllowSubmitBlockWhenNotSynced {
+			isGenesisVirtualSelectedParent, err := flow.isGenesisVirtualSelectedParent()
+			if err != nil {
+				return err
+			}
+
+			if isGenesisVirtualSelectedParent {
+				log.Infof("Cannot process orphan %s for a node with only the genesis block. The node needs to IBD "+
+					"to the recent pruning point before normal operation can resume.", blockHash)
+				return nil
+			}
+		}
+
+		log.Debugf("Block %s is within orphan resolution range. "+
+			"Adding it to the orphan set", blockHash)
+		flow.AddOrphan(block)
+		log.Debugf("Requesting block %s missing ancestors", blockHash)
+		return flow.AddOrphanRootsToQueue(blockHash)
+	}
+
+	// Start IBD unless we already are in IBD
+	log.Debugf("Block %s is out of orphan resolution range. "+
+		"Attempting to start IBD against it.", blockHash)
+
+	// Send the block to IBD flow via the IBDRequestChannel.
+	// Note that this is a non-blocking send, since if IBD is already running, there is no need to trigger it
+	select {
+	case flow.peer.IBDRequestChannel() <- block:
+	default:
+	}
+	return nil
+}
+
+func (flow *handleRelayInvsFlow) isGenesisVirtualSelectedParent() (bool, error) {
+	virtualSelectedParent, err := flow.Domain().Consensus().GetVirtualSelectedParent()
+	if err != nil {
+		return false, err
+	}
+
+	return virtualSelectedParent.Equal(flow.Config().NetParams().GenesisHash), nil
+}
+
+func (flow *handleRelayInvsFlow) isChildOfGenesis(block *externalapi.DomainBlock) bool {
+	parents := block.Header.DirectParents()
+	return len(parents) == 1 && parents[0].Equal(flow.Config().NetParams().GenesisHash)
+}
+
+// isBlockInOrphanResolutionRange finds out whether the given blockHash should be
+// retrieved via the unorphaning mechanism or via IBD. This method sends a
+// getBlockLocator request to the peer with a limit of orphanResolutionRange.
+// In the response, if we know none of the hashes, we should retrieve the given
+// blockHash via IBD. Otherwise, via unorphaning.
+func (flow *handleRelayInvsFlow) isBlockInOrphanResolutionRange(blockHash *externalapi.DomainHash) (bool, error) {
+	err := flow.sendGetBlockLocator(blockHash, orphanResolutionRange)
+	if err != nil {
+		return false, err
+	}
+
+	blockLocatorHashes, err := flow.receiveBlockLocator()
+	if err != nil {
+		return false, err
+	}
+	for _, blockLocatorHash := range blockLocatorHashes {
+		blockInfo, err := flow.Domain().Consensus().GetBlockInfo(blockLocatorHash)
+		if err != nil {
+			return false, err
+		}
+		if blockInfo.Exists && blockInfo.BlockStatus != externalapi.StatusHeaderOnly {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
+func (flow *handleRelayInvsFlow) AddOrphanRootsToQueue(orphan *externalapi.DomainHash) error {
+	orphanRoots, orphanExists, err := flow.GetOrphanRoots(orphan)
+	if err != nil {
+		return err
+	}
+
+	if !orphanExists {
+		log.Infof("Orphan block %s was missing from the orphan pool while requesting for its roots. This "+
+			"probably happened because it was randomly evicted immediately after it was added.", orphan)
+	}
+
+	if len(orphanRoots) == 0 {
+		// In some rare cases we get here when there are no orphan roots already
+		return nil
+	}
+	log.Infof("Block %s has %d missing ancestors. Adding them to the invs queue...", orphan, len(orphanRoots))
+
+	invMessages := make([]*appmessage.MsgInvRelayBlock, len(orphanRoots))
+	for i, root := range orphanRoots {
+		log.Debugf("Adding block %s missing ancestor %s to the invs queue", orphan, root)
+		invMessages[i] = appmessage.NewMsgInvBlock(root)
+	}
+
+	flow.invsQueue = append(invMessages, flow.invsQueue...)
+	return nil
+}

app/protocol/flows/v5/blockrelay/handle_request_anticone.go

@@ -0,0 +1,95 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/peer"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/infrastructure/config"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"sort"
+)
+
+// RequestAnticoneContext is the interface for the context needed for the HandleRequestHeaders flow.
+type RequestAnticoneContext interface {
+	Domain() domain.Domain
+	Config() *config.Config
+}
+
+type handleRequestAnticoneFlow struct {
+	RequestAnticoneContext
+	incomingRoute, outgoingRoute *router.Route
+	peer                         *peer.Peer
+}
+
+// HandleRequestAnticone handles RequestAnticone messages
+func HandleRequestAnticone(context RequestAnticoneContext, incomingRoute *router.Route,
+	outgoingRoute *router.Route, peer *peer.Peer) error {
+
+	flow := &handleRequestAnticoneFlow{
+		RequestAnticoneContext: context,
+		incomingRoute:          incomingRoute,
+		outgoingRoute:          outgoingRoute,
+		peer:                   peer,
+	}
+	return flow.start()
+}
+
+func (flow *handleRequestAnticoneFlow) start() error {
+	for {
+		blockHash, contextHash, err := receiveRequestAnticone(flow.incomingRoute)
+		if err != nil {
+			return err
+		}
+		log.Debugf("Received requestAnticone with blockHash: %s, contextHash: %s", blockHash, contextHash)
+		log.Debugf("Getting past(%s) cap anticone(%s) for peer %s", contextHash, blockHash, flow.peer)
+
+		// GetAnticone is expected to be called by the syncee for getting the anticone of the header selected tip
+		// intersected by past of relayed block, and is thus expected to be bounded by mergeset limit since
+		// we relay blocks only if they enter virtual's mergeset. We add 2 for a small margin error.
+		blockHashes, err := flow.Domain().Consensus().GetAnticone(blockHash, contextHash,
+			flow.Config().ActiveNetParams.MergeSetSizeLimit+2)
+		if err != nil {
+			return protocolerrors.Wrap(true, err, "Failed querying anticone")
+		}
+		log.Debugf("Got %d header hashes in past(%s) cap anticone(%s)", len(blockHashes), contextHash, blockHash)
+
+		blockHeaders := make([]*appmessage.MsgBlockHeader, len(blockHashes))
+		for i, blockHash := range blockHashes {
+			blockHeader, err := flow.Domain().Consensus().GetBlockHeader(blockHash)
+			if err != nil {
+				return err
+			}
+			blockHeaders[i] = appmessage.DomainBlockHeaderToBlockHeader(blockHeader)
+		}
+
+		// We sort the headers in bottom-up topological order before sending
+		sort.Slice(blockHeaders, func(i, j int) bool {
+			return blockHeaders[i].BlueWork.Cmp(blockHeaders[j].BlueWork) < 0
+		})
+
+		blockHeadersMessage := appmessage.NewBlockHeadersMessage(blockHeaders)
+		err = flow.outgoingRoute.Enqueue(blockHeadersMessage)
+		if err != nil {
+			return err
+		}
+
+		err = flow.outgoingRoute.Enqueue(appmessage.NewMsgDoneHeaders())
+		if err != nil {
+			return err
+		}
+	}
+}
+
+func receiveRequestAnticone(incomingRoute *router.Route) (blockHash *externalapi.DomainHash,
+	contextHash *externalapi.DomainHash, err error) {
+
+	message, err := incomingRoute.Dequeue()
+	if err != nil {
+		return nil, nil, err
+	}
+	msgRequestAnticone := message.(*appmessage.MsgRequestAnticone)
+
+	return msgRequestAnticone.BlockHash, msgRequestAnticone.ContextHash, nil
+}

app/protocol/flows/v5/blockrelay/handle_request_block_locator.go

@@ -0,0 +1,75 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+// RequestBlockLocatorContext is the interface for the context needed for the HandleRequestBlockLocator flow.
+type RequestBlockLocatorContext interface {
+	Domain() domain.Domain
+}
+
+type handleRequestBlockLocatorFlow struct {
+	RequestBlockLocatorContext
+	incomingRoute, outgoingRoute *router.Route
+}
+
+// HandleRequestBlockLocator handles getBlockLocator messages
+func HandleRequestBlockLocator(context RequestBlockLocatorContext, incomingRoute *router.Route,
+	outgoingRoute *router.Route) error {
+
+	flow := &handleRequestBlockLocatorFlow{
+		RequestBlockLocatorContext: context,
+		incomingRoute:              incomingRoute,
+		outgoingRoute:              outgoingRoute,
+	}
+	return flow.start()
+}
+
+func (flow *handleRequestBlockLocatorFlow) start() error {
+	for {
+		highHash, limit, err := flow.receiveGetBlockLocator()
+		if err != nil {
+			return err
+		}
+		log.Debugf("Received getBlockLocator with highHash: %s, limit: %d", highHash, limit)
+
+		locator, err := flow.Domain().Consensus().CreateBlockLocatorFromPruningPoint(highHash, limit)
+		if err != nil || len(locator) == 0 {
+			if err != nil {
+				log.Debugf("Received error from CreateBlockLocatorFromPruningPoint: %s", err)
+			}
+			return protocolerrors.Errorf(true, "couldn't build a block "+
+				"locator between the pruning point and %s", highHash)
+		}
+
+		err = flow.sendBlockLocator(locator)
+		if err != nil {
+			return err
+		}
+	}
+}
+
+func (flow *handleRequestBlockLocatorFlow) receiveGetBlockLocator() (highHash *externalapi.DomainHash, limit uint32, err error) {
+
+	message, err := flow.incomingRoute.Dequeue()
+	if err != nil {
+		return nil, 0, err
+	}
+	msgGetBlockLocator := message.(*appmessage.MsgRequestBlockLocator)
+
+	return msgGetBlockLocator.HighHash, msgGetBlockLocator.Limit, nil
+}
+
+func (flow *handleRequestBlockLocatorFlow) sendBlockLocator(locator externalapi.BlockLocator) error {
+	msgBlockLocator := appmessage.NewMsgBlockLocator(locator)
+	err := flow.outgoingRoute.Enqueue(msgBlockLocator)
+	if err != nil {
+		return err
+	}
+	return nil
+}

app/protocol/flows/v5/blockrelay/handle_request_headers.go

@@ -0,0 +1,116 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/protocol/peer"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+// This constant must be equal at both syncer and syncee. Therefore, never (!!) change this constant unless a new p2p
+// version is introduced. See `TestIBDBatchSizeLessThanRouteCapacity` as well.
+const ibdBatchSize = 99
+
+// RequestHeadersContext is the interface for the context needed for the HandleRequestHeaders flow.
+type RequestHeadersContext interface {
+	Domain() domain.Domain
+}
+
+type handleRequestHeadersFlow struct {
+	RequestHeadersContext
+	incomingRoute, outgoingRoute *router.Route
+	peer                         *peer.Peer
+}
+
+// HandleRequestHeaders handles RequestHeaders messages
+func HandleRequestHeaders(context RequestHeadersContext, incomingRoute *router.Route,
+	outgoingRoute *router.Route, peer *peer.Peer) error {
+
+	flow := &handleRequestHeadersFlow{
+		RequestHeadersContext: context,
+		incomingRoute:         incomingRoute,
+		outgoingRoute:         outgoingRoute,
+		peer:                  peer,
+	}
+	return flow.start()
+}
+
+func (flow *handleRequestHeadersFlow) start() error {
+	for {
+		lowHash, highHash, err := receiveRequestHeaders(flow.incomingRoute)
+		if err != nil {
+			return err
+		}
+		log.Debugf("Received requestHeaders with lowHash: %s, highHash: %s", lowHash, highHash)
+
+		isLowSelectedAncestorOfHigh, err := flow.Domain().Consensus().IsInSelectedParentChainOf(lowHash, highHash)
+		if err != nil {
+			return err
+		}
+		if !isLowSelectedAncestorOfHigh {
+			return protocolerrors.Errorf(true, "Expected %s to be on the selected chain of %s",
+				lowHash, highHash)
+		}
+
+		for !lowHash.Equal(highHash) {
+			log.Debugf("Getting block headers between %s and %s to %s", lowHash, highHash, flow.peer)
+
+			// GetHashesBetween is a relatively heavy operation so we limit it
+			// in order to avoid locking the consensus for too long
+			// maxBlocks MUST be >= MergeSetSizeLimit + 1
+			const maxBlocks = 1 << 10
+			blockHashes, _, err := flow.Domain().Consensus().GetHashesBetween(lowHash, highHash, maxBlocks)
+			if err != nil {
+				return err
+			}
+			log.Debugf("Got %d header hashes above lowHash %s", len(blockHashes), lowHash)
+
+			blockHeaders := make([]*appmessage.MsgBlockHeader, len(blockHashes))
+			for i, blockHash := range blockHashes {
+				blockHeader, err := flow.Domain().Consensus().GetBlockHeader(blockHash)
+				if err != nil {
+					return err
+				}
+				blockHeaders[i] = appmessage.DomainBlockHeaderToBlockHeader(blockHeader)
+			}
+
+			blockHeadersMessage := appmessage.NewBlockHeadersMessage(blockHeaders)
+			err = flow.outgoingRoute.Enqueue(blockHeadersMessage)
+			if err != nil {
+				return err
+			}
+
+			message, err := flow.incomingRoute.Dequeue()
+			if err != nil {
+				return err
+			}
+			if _, ok := message.(*appmessage.MsgRequestNextHeaders); !ok {
+				return protocolerrors.Errorf(true, "received unexpected message type. "+
+					"expected: %s, got: %s", appmessage.CmdRequestNextHeaders, message.Command())
+			}
+
+			// The next lowHash is the last element in blockHashes
+			lowHash = blockHashes[len(blockHashes)-1]
+		}
+
+		err = flow.outgoingRoute.Enqueue(appmessage.NewMsgDoneHeaders())
+		if err != nil {
+			return err
+		}
+	}
+}
+
+func receiveRequestHeaders(incomingRoute *router.Route) (lowHash *externalapi.DomainHash,
+	highHash *externalapi.DomainHash, err error) {
+
+	message, err := incomingRoute.Dequeue()
+	if err != nil {
+		return nil, nil, err
+	}
+	msgRequestIBDBlocks := message.(*appmessage.MsgRequestHeaders)
+
+	return msgRequestIBDBlocks.LowHash, msgRequestIBDBlocks.HighHash, nil
+}

app/protocol/flows/v5/blockrelay/handle_request_pruning_point_utxo_set.go

@@ -0,0 +1,140 @@
+package blockrelay
+
+import (
+	"errors"
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/common"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/domain/consensus/ruleerrors"
+	"github.com/kaspanet/kaspad/infrastructure/logger"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+// HandleRequestPruningPointUTXOSetContext is the interface for the context needed for the HandleRequestPruningPointUTXOSet flow.
+type HandleRequestPruningPointUTXOSetContext interface {
+	Domain() domain.Domain
+}
+
+type handleRequestPruningPointUTXOSetFlow struct {
+	HandleRequestPruningPointUTXOSetContext
+	incomingRoute, outgoingRoute *router.Route
+}
+
+// HandleRequestPruningPointUTXOSet listens to appmessage.MsgRequestPruningPointUTXOSet messages and sends
+// the pruning point UTXO set and block body.
+func HandleRequestPruningPointUTXOSet(context HandleRequestPruningPointUTXOSetContext, incomingRoute,
+	outgoingRoute *router.Route) error {
+
+	flow := &handleRequestPruningPointUTXOSetFlow{
+		HandleRequestPruningPointUTXOSetContext: context,
+		incomingRoute:                           incomingRoute,
+		outgoingRoute:                           outgoingRoute,
+	}
+
+	return flow.start()
+}
+
+func (flow *handleRequestPruningPointUTXOSetFlow) start() error {
+	for {
+		msgRequestPruningPointUTXOSet, err := flow.waitForRequestPruningPointUTXOSetMessages()
+		if err != nil {
+			return err
+		}
+
+		err = flow.handleRequestPruningPointUTXOSetMessage(msgRequestPruningPointUTXOSet)
+		if err != nil {
+			return err
+		}
+	}
+}
+
+func (flow *handleRequestPruningPointUTXOSetFlow) handleRequestPruningPointUTXOSetMessage(
+	msgRequestPruningPointUTXOSet *appmessage.MsgRequestPruningPointUTXOSet) error {
+
+	onEnd := logger.LogAndMeasureExecutionTime(log, "handleRequestPruningPointUTXOSetFlow")
+	defer onEnd()
+
+	log.Debugf("Got request for pruning point UTXO set")
+
+	return flow.sendPruningPointUTXOSet(msgRequestPruningPointUTXOSet)
+}
+
+func (flow *handleRequestPruningPointUTXOSetFlow) waitForRequestPruningPointUTXOSetMessages() (
+	*appmessage.MsgRequestPruningPointUTXOSet, error) {
+
+	message, err := flow.incomingRoute.Dequeue()
+	if err != nil {
+		return nil, err
+	}
+	msgRequestPruningPointUTXOSet, ok := message.(*appmessage.MsgRequestPruningPointUTXOSet)
+	if !ok {
+		// TODO: Change to shouldBan: true once we fix the bug of getting redundant messages
+		return nil, protocolerrors.Errorf(false, "received unexpected message type. "+
+			"expected: %s, got: %s", appmessage.CmdRequestPruningPointUTXOSet, message.Command())
+	}
+	return msgRequestPruningPointUTXOSet, nil
+}
+
+func (flow *handleRequestPruningPointUTXOSetFlow) sendPruningPointUTXOSet(
+	msgRequestPruningPointUTXOSet *appmessage.MsgRequestPruningPointUTXOSet) error {
+
+	// Send the UTXO set in `step`-sized chunks
+	const step = 1000
+	var fromOutpoint *externalapi.DomainOutpoint
+	chunksSent := 0
+	for {
+		pruningPointUTXOs, err := flow.Domain().Consensus().GetPruningPointUTXOs(
+			msgRequestPruningPointUTXOSet.PruningPointHash, fromOutpoint, step)
+		if err != nil {
+			if errors.Is(err, ruleerrors.ErrWrongPruningPointHash) {
+				return flow.outgoingRoute.Enqueue(appmessage.NewMsgUnexpectedPruningPoint())
+			}
+		}
+
+		log.Debugf("Retrieved %d UTXOs for pruning block %s",
+			len(pruningPointUTXOs), msgRequestPruningPointUTXOSet.PruningPointHash)
+
+		outpointAndUTXOEntryPairs :=
+			appmessage.DomainOutpointAndUTXOEntryPairsToOutpointAndUTXOEntryPairs(pruningPointUTXOs)
+		err = flow.outgoingRoute.Enqueue(appmessage.NewMsgPruningPointUTXOSetChunk(outpointAndUTXOEntryPairs))
+		if err != nil {
+			return err
+		}
+
+		finished := len(pruningPointUTXOs) < step
+		if finished && chunksSent%ibdBatchSize != 0 {
+			log.Debugf("Finished sending UTXOs for pruning block %s",
+				msgRequestPruningPointUTXOSet.PruningPointHash)
+
+			return flow.outgoingRoute.Enqueue(appmessage.NewMsgDonePruningPointUTXOSetChunks())
+		}
+
+		if len(pruningPointUTXOs) > 0 {
+			fromOutpoint = pruningPointUTXOs[len(pruningPointUTXOs)-1].Outpoint
+		}
+		chunksSent++
+
+		// Wait for the peer to request more chunks every `ibdBatchSize` chunks
+		if chunksSent%ibdBatchSize == 0 {
+			message, err := flow.incomingRoute.DequeueWithTimeout(common.DefaultTimeout)
+			if err != nil {
+				return err
+			}
+			_, ok := message.(*appmessage.MsgRequestNextPruningPointUTXOSetChunk)
+			if !ok {
+				// TODO: Change to shouldBan: true once we fix the bug of getting redundant messages
+				return protocolerrors.Errorf(false, "received unexpected message type. "+
+					"expected: %s, got: %s", appmessage.CmdRequestNextPruningPointUTXOSetChunk, message.Command())
+			}
+
+			if finished {
+				log.Debugf("Finished sending UTXOs for pruning block %s",
+					msgRequestPruningPointUTXOSet.PruningPointHash)
+
+				return flow.outgoingRoute.Enqueue(appmessage.NewMsgDonePruningPointUTXOSetChunks())
+			}
+		}
+	}
+}

app/protocol/flows/v5/blockrelay/ibd.go

@@ -0,0 +1,723 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/common"
+	peerpkg "github.com/kaspanet/kaspad/app/protocol/peer"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/domain/consensus/ruleerrors"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/consensushashing"
+	"github.com/kaspanet/kaspad/infrastructure/config"
+	"github.com/kaspanet/kaspad/infrastructure/logger"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"github.com/pkg/errors"
+	"time"
+)
+
+// IBDContext is the interface for the context needed for the HandleIBD flow.
+type IBDContext interface {
+	Domain() domain.Domain
+	Config() *config.Config
+	OnNewBlock(block *externalapi.DomainBlock, virtualChangeSet *externalapi.VirtualChangeSet) error
+	OnVirtualChange(virtualChangeSet *externalapi.VirtualChangeSet) error
+	OnPruningPointUTXOSetOverride() error
+	IsIBDRunning() bool
+	TrySetIBDRunning(ibdPeer *peerpkg.Peer) bool
+	UnsetIBDRunning()
+	IsRecoverableError(err error) bool
+}
+
+type handleIBDFlow struct {
+	IBDContext
+	incomingRoute, outgoingRoute *router.Route
+	peer                         *peerpkg.Peer
+}
+
+// HandleIBD handles IBD
+func HandleIBD(context IBDContext, incomingRoute *router.Route, outgoingRoute *router.Route,
+	peer *peerpkg.Peer) error {
+
+	flow := &handleIBDFlow{
+		IBDContext:    context,
+		incomingRoute: incomingRoute,
+		outgoingRoute: outgoingRoute,
+		peer:          peer,
+	}
+	return flow.start()
+}
+
+func (flow *handleIBDFlow) start() error {
+	for {
+		// Wait for IBD requests triggered by other flows
+		block, ok := <-flow.peer.IBDRequestChannel()
+		if !ok {
+			return nil
+		}
+		err := flow.runIBDIfNotRunning(block)
+		if err != nil {
+			return err
+		}
+	}
+}
+
+func (flow *handleIBDFlow) runIBDIfNotRunning(block *externalapi.DomainBlock) error {
+	wasIBDNotRunning := flow.TrySetIBDRunning(flow.peer)
+	if !wasIBDNotRunning {
+		log.Debugf("IBD is already running")
+		return nil
+	}
+
+	isFinishedSuccessfully := false
+	defer func() {
+		flow.UnsetIBDRunning()
+		flow.logIBDFinished(isFinishedSuccessfully)
+	}()
+
+	relayBlockHash := consensushashing.BlockHash(block)
+
+	log.Debugf("IBD started with peer %s and relayBlockHash %s", flow.peer, relayBlockHash)
+	log.Debugf("Syncing blocks up to %s", relayBlockHash)
+	log.Debugf("Trying to find highest known syncer chain block from peer %s with relay hash %s", flow.peer, relayBlockHash)
+
+	syncerHeaderSelectedTipHash, highestKnownSyncerChainHash, err := flow.negotiateMissingSyncerChainSegment()
+	if err != nil {
+		return err
+	}
+
+	shouldDownloadHeadersProof, shouldSync, err := flow.shouldSyncAndShouldDownloadHeadersProof(
+		block, highestKnownSyncerChainHash)
+	if err != nil {
+		return err
+	}
+
+	if !shouldSync {
+		return nil
+	}
+
+	if shouldDownloadHeadersProof {
+		log.Infof("Starting IBD with headers proof")
+		err := flow.ibdWithHeadersProof(syncerHeaderSelectedTipHash, relayBlockHash, block.Header.DAAScore())
+		if err != nil {
+			return err
+		}
+	} else {
+		if flow.Config().NetParams().DisallowDirectBlocksOnTopOfGenesis && !flow.Config().AllowSubmitBlockWhenNotSynced {
+			isGenesisVirtualSelectedParent, err := flow.isGenesisVirtualSelectedParent()
+			if err != nil {
+				return err
+			}
+
+			if isGenesisVirtualSelectedParent {
+				log.Infof("Cannot IBD to %s because it won't change the pruning point. The node needs to IBD "+
+					"to the recent pruning point before normal operation can resume.", relayBlockHash)
+				return nil
+			}
+		}
+
+		err = flow.syncPruningPointFutureHeaders(
+			flow.Domain().Consensus(),
+			syncerHeaderSelectedTipHash, highestKnownSyncerChainHash, relayBlockHash, block.Header.DAAScore())
+		if err != nil {
+			return err
+		}
+	}
+
+	// We start by syncing missing bodies over the syncer selected chain
+	err = flow.syncMissingBlockBodies(syncerHeaderSelectedTipHash)
+	if err != nil {
+		return err
+	}
+	relayBlockInfo, err := flow.Domain().Consensus().GetBlockInfo(relayBlockHash)
+	if err != nil {
+		return err
+	}
+	// Relay block might be in the anticone of syncer selected tip, thus
+	// check his chain for missing bodies as well.
+	// Note: this operation can be slightly optimized to avoid the full chain search since relay block
+	// is in syncer virtual mergeset which has bounded size.
+	if relayBlockInfo.BlockStatus == externalapi.StatusHeaderOnly {
+		err = flow.syncMissingBlockBodies(relayBlockHash)
+		if err != nil {
+			return err
+		}
+	}
+
+	log.Debugf("Finished syncing blocks up to %s", relayBlockHash)
+	isFinishedSuccessfully = true
+	return nil
+}
+
+func (flow *handleIBDFlow) negotiateMissingSyncerChainSegment() (*externalapi.DomainHash, *externalapi.DomainHash, error) {
+	/*
+		Algorithm:
+			Request full selected chain block locator from syncer
+			Find the highest block which we know
+			Repeat the locator step over the new range until finding max(past(syncee) \cap chain(syncer))
+	*/
+
+	// Empty hashes indicate that the full chain is queried
+	locatorHashes, err := flow.getSyncerChainBlockLocator(nil, nil, common.DefaultTimeout)
+	if err != nil {
+		return nil, nil, err
+	}
+	if len(locatorHashes) == 0 {
+		return nil, nil, protocolerrors.Errorf(true, "Expecting initial syncer chain block locator "+
+			"to contain at least one element")
+	}
+	log.Debugf("IBD chain negotiation with peer %s started and received %d hashes (%s, %s)", flow.peer,
+		len(locatorHashes), locatorHashes[0], locatorHashes[len(locatorHashes)-1])
+	syncerHeaderSelectedTipHash := locatorHashes[0]
+	var highestKnownSyncerChainHash *externalapi.DomainHash
+	chainNegotiationRestartCounter := 0
+	chainNegotiationZoomCounts := 0
+	initialLocatorLen := len(locatorHashes)
+	for {
+		var lowestUnknownSyncerChainHash, currentHighestKnownSyncerChainHash *externalapi.DomainHash
+		for _, syncerChainHash := range locatorHashes {
+			info, err := flow.Domain().Consensus().GetBlockInfo(syncerChainHash)
+			if err != nil {
+				return nil, nil, err
+			}
+			if info.Exists {
+				currentHighestKnownSyncerChainHash = syncerChainHash
+				break
+			}
+			lowestUnknownSyncerChainHash = syncerChainHash
+		}
+		// No unknown blocks, break. Note this can only happen in the first iteration
+		if lowestUnknownSyncerChainHash == nil {
+			highestKnownSyncerChainHash = currentHighestKnownSyncerChainHash
+			break
+		}
+		// No shared block, break
+		if currentHighestKnownSyncerChainHash == nil {
+			highestKnownSyncerChainHash = nil
+			break
+		}
+		// No point in zooming further
+		if len(locatorHashes) == 1 {
+			highestKnownSyncerChainHash = currentHighestKnownSyncerChainHash
+			break
+		}
+		// Zoom in
+		locatorHashes, err = flow.getSyncerChainBlockLocator(
+			lowestUnknownSyncerChainHash,
+			currentHighestKnownSyncerChainHash, time.Second*10)
+		if err != nil {
+			return nil, nil, err
+		}
+		if len(locatorHashes) > 0 {
+			if !locatorHashes[0].Equal(lowestUnknownSyncerChainHash) ||
+				!locatorHashes[len(locatorHashes)-1].Equal(currentHighestKnownSyncerChainHash) {
+				return nil, nil, protocolerrors.Errorf(true, "Expecting the high and low "+
+					"hashes to match the locator bounds")
+			}
+
+			chainNegotiationZoomCounts++
+			log.Debugf("IBD chain negotiation with peer %s zoomed in (%d) and received %d hashes (%s, %s)", flow.peer,
+				chainNegotiationZoomCounts, len(locatorHashes), locatorHashes[0], locatorHashes[len(locatorHashes)-1])
+
+			if len(locatorHashes) == 2 {
+				// We found our search target
+				highestKnownSyncerChainHash = currentHighestKnownSyncerChainHash
+				break
+			}
+
+			if chainNegotiationZoomCounts > initialLocatorLen*2 {
+				// Since the zoom-in always queries two consecutive entries in the previous locator, it is
+				// expected to decrease in size at least every two iterations
+				return nil, nil, protocolerrors.Errorf(true,
+					"IBD chain negotiation: Number of zoom-in steps %d exceeded the upper bound of 2*%d",
+					chainNegotiationZoomCounts, initialLocatorLen)
+			}
+
+		} else { // Empty locator signals a restart due to chain changes
+			chainNegotiationZoomCounts = 0
+			chainNegotiationRestartCounter++
+			if chainNegotiationRestartCounter > 32 {
+				return nil, nil, protocolerrors.Errorf(false,
+					"IBD chain negotiation with syncer %s exceeded restart limit %d", flow.peer, chainNegotiationRestartCounter)
+			}
+			log.Warnf("IBD chain negotiation with syncer %s restarted %d times", flow.peer, chainNegotiationRestartCounter)
+
+			// An empty locator signals that the syncer chain was modified and no longer contains one of
+			// the queried hashes, so we restart the search. We use a shorter timeout here to avoid a timeout attack
+			locatorHashes, err = flow.getSyncerChainBlockLocator(nil, nil, time.Second*10)
+			if err != nil {
+				return nil, nil, err
+			}
+			if len(locatorHashes) == 0 {
+				return nil, nil, protocolerrors.Errorf(true, "Expecting initial syncer chain block locator "+
+					"to contain at least one element")
+			}
+			log.Infof("IBD chain negotiation with peer %s restarted (%d) and received %d hashes (%s, %s)", flow.peer,
+				chainNegotiationRestartCounter, len(locatorHashes), locatorHashes[0], locatorHashes[len(locatorHashes)-1])
+
+			initialLocatorLen = len(locatorHashes)
+			// Reset syncer's header selected tip
+			syncerHeaderSelectedTipHash = locatorHashes[0]
+		}
+	}
+
+	log.Debugf("Found highest known syncer chain block %s from peer %s",
+		highestKnownSyncerChainHash, flow.peer)
+
+	return syncerHeaderSelectedTipHash, highestKnownSyncerChainHash, nil
+}
+
+func (flow *handleIBDFlow) isGenesisVirtualSelectedParent() (bool, error) {
+	virtualSelectedParent, err := flow.Domain().Consensus().GetVirtualSelectedParent()
+	if err != nil {
+		return false, err
+	}
+
+	return virtualSelectedParent.Equal(flow.Config().NetParams().GenesisHash), nil
+}
+
+func (flow *handleIBDFlow) logIBDFinished(isFinishedSuccessfully bool) {
+	successString := "successfully"
+	if !isFinishedSuccessfully {
+		successString = "(interrupted)"
+	}
+	log.Infof("IBD with peer %s finished %s", flow.peer, successString)
+}
+
+func (flow *handleIBDFlow) getSyncerChainBlockLocator(
+	highHash, lowHash *externalapi.DomainHash, timeout time.Duration) ([]*externalapi.DomainHash, error) {
+
+	requestIbdChainBlockLocatorMessage := appmessage.NewMsgIBDRequestChainBlockLocator(highHash, lowHash)
+	err := flow.outgoingRoute.Enqueue(requestIbdChainBlockLocatorMessage)
+	if err != nil {
+		return nil, err
+	}
+	message, err := flow.incomingRoute.DequeueWithTimeout(timeout)
+	if err != nil {
+		return nil, err
+	}
+	switch message := message.(type) {
+	case *appmessage.MsgIBDChainBlockLocator:
+		if len(message.BlockLocatorHashes) > 64 {
+			return nil, protocolerrors.Errorf(true,
+				"Got block locator of size %d>64 while expecting locator to have size "+
+					"which is logarithmic in DAG size (which should never exceed 2^64)",
+				len(message.BlockLocatorHashes))
+		}
+		return message.BlockLocatorHashes, nil
+	default:
+		return nil, protocolerrors.Errorf(true, "received unexpected message type. "+
+			"expected: %s, got: %s", appmessage.CmdIBDChainBlockLocator, message.Command())
+	}
+}
+
+func (flow *handleIBDFlow) syncPruningPointFutureHeaders(consensus externalapi.Consensus,
+	syncerHeaderSelectedTipHash, highestKnownSyncerChainHash, relayBlockHash *externalapi.DomainHash,
+	highBlockDAAScoreHint uint64) error {
+
+	log.Infof("Downloading headers from %s", flow.peer)
+
+	if highestKnownSyncerChainHash.Equal(syncerHeaderSelectedTipHash) {
+		// No need to get syncer selected tip headers, so sync relay past and return
+		return flow.syncMissingRelayPast(consensus, syncerHeaderSelectedTipHash, relayBlockHash)
+	}
+
+	err := flow.sendRequestHeaders(highestKnownSyncerChainHash, syncerHeaderSelectedTipHash)
+	if err != nil {
+		return err
+	}
+
+	highestSharedBlockHeader, err := consensus.GetBlockHeader(highestKnownSyncerChainHash)
+	if err != nil {
+		return err
+	}
+	progressReporter := newIBDProgressReporter(highestSharedBlockHeader.DAAScore(), highBlockDAAScoreHint, "block headers")
+
+	// Keep a short queue of BlockHeadersMessages so that there's
+	// never a moment when the node is not validating and inserting
+	// headers
+	blockHeadersMessageChan := make(chan *appmessage.BlockHeadersMessage, 2)
+	errChan := make(chan error)
+	spawn("handleRelayInvsFlow-syncPruningPointFutureHeaders", func() {
+		for {
+			blockHeadersMessage, doneIBD, err := flow.receiveHeaders()
+			if err != nil {
+				errChan <- err
+				return
+			}
+			if doneIBD {
+				close(blockHeadersMessageChan)
+				return
+			}
+			if len(blockHeadersMessage.BlockHeaders) == 0 {
+				// The syncer should have sent a done message if the search completed, and not an empty list
+				errChan <- protocolerrors.Errorf(true, "Received an empty headers message from peer %s", flow.peer)
+				return
+			}
+
+			blockHeadersMessageChan <- blockHeadersMessage
+
+			err = flow.outgoingRoute.Enqueue(appmessage.NewMsgRequestNextHeaders())
+			if err != nil {
+				errChan <- err
+				return
+			}
+		}
+	})
+
+	for {
+		select {
+		case ibdBlocksMessage, ok := <-blockHeadersMessageChan:
+			if !ok {
+				return flow.syncMissingRelayPast(consensus, syncerHeaderSelectedTipHash, relayBlockHash)
+			}
+			for _, header := range ibdBlocksMessage.BlockHeaders {
+				err = flow.processHeader(consensus, header)
+				if err != nil {
+					return err
+				}
+			}
+
+			lastReceivedHeader := ibdBlocksMessage.BlockHeaders[len(ibdBlocksMessage.BlockHeaders)-1]
+			progressReporter.reportProgress(len(ibdBlocksMessage.BlockHeaders), lastReceivedHeader.DAAScore)
+		case err := <-errChan:
+			return err
+		}
+	}
+}
+
+func (flow *handleIBDFlow) syncMissingRelayPast(consensus externalapi.Consensus, syncerHeaderSelectedTipHash *externalapi.DomainHash, relayBlockHash *externalapi.DomainHash) error {
+	// Finished downloading syncer selected tip blocks,
+	// check if we already have the triggering relayBlockHash
+	relayBlockInfo, err := consensus.GetBlockInfo(relayBlockHash)
+	if err != nil {
+		return err
+	}
+	if !relayBlockInfo.Exists {
+		// Send a special header request for the selected tip anticone. This is expected to
+		// be a small set, as it is bounded to the size of virtual's mergeset.
+		err = flow.sendRequestAnticone(syncerHeaderSelectedTipHash, relayBlockHash)
+		if err != nil {
+			return err
+		}
+		anticoneHeadersMessage, anticoneDone, err := flow.receiveHeaders()
+		if err != nil {
+			return err
+		}
+		if anticoneDone {
+			return protocolerrors.Errorf(true,
+				"Expected one anticone header chunk for past(%s) cap anticone(%s) but got zero",
+				relayBlockHash, syncerHeaderSelectedTipHash)
+		}
+		_, anticoneDone, err = flow.receiveHeaders()
+		if err != nil {
+			return err
+		}
+		if !anticoneDone {
+			return protocolerrors.Errorf(true,
+				"Expected only one anticone header chunk for past(%s) cap anticone(%s)",
+				relayBlockHash, syncerHeaderSelectedTipHash)
+		}
+		for _, header := range anticoneHeadersMessage.BlockHeaders {
+			err = flow.processHeader(consensus, header)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	// If the relayBlockHash has still not been received, the peer is misbehaving
+	relayBlockInfo, err = consensus.GetBlockInfo(relayBlockHash)
+	if err != nil {
+		return err
+	}
+	if !relayBlockInfo.Exists {
+		return protocolerrors.Errorf(true, "did not receive "+
+			"relayBlockHash block %s from peer %s during block download", relayBlockHash, flow.peer)
+	}
+	return nil
+}
+
+func (flow *handleIBDFlow) sendRequestAnticone(
+	syncerHeaderSelectedTipHash, relayBlockHash *externalapi.DomainHash) error {
+
+	msgRequestAnticone := appmessage.NewMsgRequestAnticone(syncerHeaderSelectedTipHash, relayBlockHash)
+	return flow.outgoingRoute.Enqueue(msgRequestAnticone)
+}
+
+func (flow *handleIBDFlow) sendRequestHeaders(
+	highestKnownSyncerChainHash, syncerHeaderSelectedTipHash *externalapi.DomainHash) error {
+
+	msgRequestHeaders := appmessage.NewMsgRequstHeaders(highestKnownSyncerChainHash, syncerHeaderSelectedTipHash)
+	return flow.outgoingRoute.Enqueue(msgRequestHeaders)
+}
+
+func (flow *handleIBDFlow) receiveHeaders() (msgIBDBlock *appmessage.BlockHeadersMessage, doneHeaders bool, err error) {
+	message, err := flow.incomingRoute.DequeueWithTimeout(common.DefaultTimeout)
+	if err != nil {
+		return nil, false, err
+	}
+	switch message := message.(type) {
+	case *appmessage.BlockHeadersMessage:
+		return message, false, nil
+	case *appmessage.MsgDoneHeaders:
+		return nil, true, nil
+	default:
+		return nil, false,
+			protocolerrors.Errorf(true, "received unexpected message type. "+
+				"expected: %s or %s, got: %s",
+				appmessage.CmdBlockHeaders,
+				appmessage.CmdDoneHeaders,
+				message.Command())
+	}
+}
+
+func (flow *handleIBDFlow) processHeader(consensus externalapi.Consensus, msgBlockHeader *appmessage.MsgBlockHeader) error {
+	header := appmessage.BlockHeaderToDomainBlockHeader(msgBlockHeader)
+	block := &externalapi.DomainBlock{
+		Header:       header,
+		Transactions: nil,
+	}
+
+	blockHash := consensushashing.BlockHash(block)
+	blockInfo, err := consensus.GetBlockInfo(blockHash)
+	if err != nil {
+		return err
+	}
+	if blockInfo.Exists {
+		log.Debugf("Block header %s is already in the DAG. Skipping...", blockHash)
+		return nil
+	}
+	_, err = consensus.ValidateAndInsertBlock(block, false)
+	if err != nil {
+		if !errors.As(err, &ruleerrors.RuleError{}) {
+			return errors.Wrapf(err, "failed to process header %s during IBD", blockHash)
+		}
+
+		if errors.Is(err, ruleerrors.ErrDuplicateBlock) {
+			log.Debugf("Skipping block header %s as it is a duplicate", blockHash)
+		} else {
+			log.Infof("Rejected block header %s from %s during IBD: %s", blockHash, flow.peer, err)
+			return protocolerrors.Wrapf(true, err, "got invalid block header %s during IBD", blockHash)
+		}
+	}
+
+	return nil
+}
+
+func (flow *handleIBDFlow) validatePruningPointFutureHeaderTimestamps() error {
+	headerSelectedTipHash, err := flow.Domain().StagingConsensus().GetHeadersSelectedTip()
+	if err != nil {
+		return err
+	}
+	headerSelectedTipHeader, err := flow.Domain().StagingConsensus().GetBlockHeader(headerSelectedTipHash)
+	if err != nil {
+		return err
+	}
+	headerSelectedTipTimestamp := headerSelectedTipHeader.TimeInMilliseconds()
+
+	currentSelectedTipHash, err := flow.Domain().Consensus().GetHeadersSelectedTip()
+	if err != nil {
+		return err
+	}
+	currentSelectedTipHeader, err := flow.Domain().Consensus().GetBlockHeader(currentSelectedTipHash)
+	if err != nil {
+		return err
+	}
+	currentSelectedTipTimestamp := currentSelectedTipHeader.TimeInMilliseconds()
+
+	if headerSelectedTipTimestamp < currentSelectedTipTimestamp {
+		return protocolerrors.Errorf(false, "the timestamp of the candidate selected "+
+			"tip is smaller than the current selected tip")
+	}
+
+	minTimestampDifferenceInMilliseconds := (10 * time.Minute).Milliseconds()
+	if headerSelectedTipTimestamp-currentSelectedTipTimestamp < minTimestampDifferenceInMilliseconds {
+		return protocolerrors.Errorf(false, "difference between the timestamps of "+
+			"the current pruning point and the candidate pruning point is too small. Aborting IBD...")
+	}
+	return nil
+}
+
+func (flow *handleIBDFlow) receiveAndInsertPruningPointUTXOSet(
+	consensus externalapi.Consensus, pruningPointHash *externalapi.DomainHash) (bool, error) {
+
+	onEnd := logger.LogAndMeasureExecutionTime(log, "receiveAndInsertPruningPointUTXOSet")
+	defer onEnd()
+
+	receivedChunkCount := 0
+	receivedUTXOCount := 0
+	for {
+		message, err := flow.incomingRoute.DequeueWithTimeout(common.DefaultTimeout)
+		if err != nil {
+			return false, err
+		}
+
+		switch message := message.(type) {
+		case *appmessage.MsgPruningPointUTXOSetChunk:
+			receivedUTXOCount += len(message.OutpointAndUTXOEntryPairs)
+			domainOutpointAndUTXOEntryPairs :=
+				appmessage.OutpointAndUTXOEntryPairsToDomainOutpointAndUTXOEntryPairs(message.OutpointAndUTXOEntryPairs)
+
+			err := consensus.AppendImportedPruningPointUTXOs(domainOutpointAndUTXOEntryPairs)
+			if err != nil {
+				return false, err
+			}
+
+			receivedChunkCount++
+			if receivedChunkCount%ibdBatchSize == 0 {
+				log.Debugf("Received %d UTXO set chunks so far, totaling in %d UTXOs",
+					receivedChunkCount, receivedUTXOCount)
+
+				requestNextPruningPointUTXOSetChunkMessage := appmessage.NewMsgRequestNextPruningPointUTXOSetChunk()
+				err := flow.outgoingRoute.Enqueue(requestNextPruningPointUTXOSetChunkMessage)
+				if err != nil {
+					return false, err
+				}
+			}
+
+		case *appmessage.MsgDonePruningPointUTXOSetChunks:
+			log.Infof("Finished receiving the UTXO set. Total UTXOs: %d", receivedUTXOCount)
+			return true, nil
+
+		case *appmessage.MsgUnexpectedPruningPoint:
+			log.Infof("Could not receive the next UTXO chunk because the pruning point %s "+
+				"is no longer the pruning point of peer %s", pruningPointHash, flow.peer)
+			return false, nil
+
+		default:
+			return false, protocolerrors.Errorf(true, "received unexpected message type. "+
+				"expected: %s or %s or %s, got: %s", appmessage.CmdPruningPointUTXOSetChunk,
+				appmessage.CmdDonePruningPointUTXOSetChunks, appmessage.CmdUnexpectedPruningPoint, message.Command(),
+			)
+		}
+	}
+}
+
+func (flow *handleIBDFlow) syncMissingBlockBodies(highHash *externalapi.DomainHash) error {
+	hashes, err := flow.Domain().Consensus().GetMissingBlockBodyHashes(highHash)
+	if err != nil {
+		return err
+	}
+	if len(hashes) == 0 {
+		// Blocks can be inserted inside the DAG during IBD if those were requested before IBD started.
+		// In rare cases, all the IBD blocks might be already inserted by the time we reach this point.
+		// In these cases - GetMissingBlockBodyHashes would return an empty array.
+		log.Debugf("No missing block body hashes found.")
+		return nil
+	}
+
+	lowBlockHeader, err := flow.Domain().Consensus().GetBlockHeader(hashes[0])
+	if err != nil {
+		return err
+	}
+	highBlockHeader, err := flow.Domain().Consensus().GetBlockHeader(hashes[len(hashes)-1])
+	if err != nil {
+		return err
+	}
+	progressReporter := newIBDProgressReporter(lowBlockHeader.DAAScore(), highBlockHeader.DAAScore(), "blocks")
+	highestProcessedDAAScore := lowBlockHeader.DAAScore()
+
+	for offset := 0; offset < len(hashes); offset += ibdBatchSize {
+		var hashesToRequest []*externalapi.DomainHash
+		if offset+ibdBatchSize < len(hashes) {
+			hashesToRequest = hashes[offset : offset+ibdBatchSize]
+		} else {
+			hashesToRequest = hashes[offset:]
+		}
+
+		err := flow.outgoingRoute.Enqueue(appmessage.NewMsgRequestIBDBlocks(hashesToRequest))
+		if err != nil {
+			return err
+		}
+
+		for _, expectedHash := range hashesToRequest {
+			message, err := flow.incomingRoute.DequeueWithTimeout(common.DefaultTimeout)
+			if err != nil {
+				return err
+			}
+
+			msgIBDBlock, ok := message.(*appmessage.MsgIBDBlock)
+			if !ok {
+				return protocolerrors.Errorf(true, "received unexpected message type. "+
+					"expected: %s, got: %s", appmessage.CmdIBDBlock, message.Command())
+			}
+
+			block := appmessage.MsgBlockToDomainBlock(msgIBDBlock.MsgBlock)
+			blockHash := consensushashing.BlockHash(block)
+			if !expectedHash.Equal(blockHash) {
+				return protocolerrors.Errorf(true, "expected block %s but got %s", expectedHash, blockHash)
+			}
+
+			err = flow.banIfBlockIsHeaderOnly(block)
+			if err != nil {
+				return err
+			}
+
+			virtualChangeSet, err := flow.Domain().Consensus().ValidateAndInsertBlock(block, false)
+			if err != nil {
+				if errors.Is(err, ruleerrors.ErrDuplicateBlock) {
+					log.Debugf("Skipping IBD Block %s as it has already been added to the DAG", blockHash)
+					continue
+				}
+				return protocolerrors.ConvertToBanningProtocolErrorIfRuleError(err, "invalid block %s", blockHash)
+			}
+			err = flow.OnNewBlock(block, virtualChangeSet)
+			if err != nil {
+				return err
+			}
+
+			highestProcessedDAAScore = block.Header.DAAScore()
+		}
+
+		progressReporter.reportProgress(len(hashesToRequest), highestProcessedDAAScore)
+	}
+
+	return flow.resolveVirtual(highestProcessedDAAScore)
+}
+
+func (flow *handleIBDFlow) banIfBlockIsHeaderOnly(block *externalapi.DomainBlock) error {
+	if len(block.Transactions) == 0 {
+		return protocolerrors.Errorf(true, "sent header of %s block where expected block with body",
+			consensushashing.BlockHash(block))
+	}
+
+	return nil
+}
+
+func (flow *handleIBDFlow) resolveVirtual(estimatedVirtualDAAScoreTarget uint64) error {
+	virtualDAAScoreStart, err := flow.Domain().Consensus().GetVirtualDAAScore()
+	if err != nil {
+		return err
+	}
+
+	for i := 0; ; i++ {
+		if i%10 == 0 {
+			virtualDAAScore, err := flow.Domain().Consensus().GetVirtualDAAScore()
+			if err != nil {
+				return err
+			}
+			var percents int
+			if estimatedVirtualDAAScoreTarget-virtualDAAScoreStart <= 0 {
+				percents = 100
+			} else {
+				percents = int(float64(virtualDAAScore-virtualDAAScoreStart) / float64(estimatedVirtualDAAScoreTarget-virtualDAAScoreStart) * 100)
+			}
+			log.Infof("Resolving virtual. Estimated progress: %d%%", percents)
+		}
+		virtualChangeSet, isCompletelyResolved, err := flow.Domain().Consensus().ResolveVirtual()
+		if err != nil {
+			return err
+		}
+
+		err = flow.OnVirtualChange(virtualChangeSet)
+		if err != nil {
+			return err
+		}
+
+		if isCompletelyResolved {
+			log.Infof("Resolved virtual")
+			return nil
+		}
+	}
+}

app/protocol/flows/v5/blockrelay/ibd_progress_reporter.go

@@ -0,0 +1,45 @@
+package blockrelay
+
+type ibdProgressReporter struct {
+	lowDAAScore                 uint64
+	highDAAScore                uint64
+	objectName                  string
+	totalDAAScoreDifference     uint64
+	lastReportedProgressPercent int
+	processed                   int
+}
+
+func newIBDProgressReporter(lowDAAScore uint64, highDAAScore uint64, objectName string) *ibdProgressReporter {
+	if highDAAScore <= lowDAAScore {
+		// Avoid a zero or negative diff
+		highDAAScore = lowDAAScore + 1
+	}
+	return &ibdProgressReporter{
+		lowDAAScore:                 lowDAAScore,
+		highDAAScore:                highDAAScore,
+		objectName:                  objectName,
+		totalDAAScoreDifference:     highDAAScore - lowDAAScore,
+		lastReportedProgressPercent: 0,
+		processed:                   0,
+	}
+}
+
+func (ipr *ibdProgressReporter) reportProgress(processedDelta int, highestProcessedDAAScore uint64) {
+	ipr.processed += processedDelta
+
+	// Avoid exploding numbers in the percentage report, since the original `highDAAScore` might have been only a hint
+	if highestProcessedDAAScore > ipr.highDAAScore {
+		ipr.highDAAScore = highestProcessedDAAScore + 1 // + 1 for keeping it at 99%
+		ipr.totalDAAScoreDifference = ipr.highDAAScore - ipr.lowDAAScore
+	}
+	relativeDAAScore := uint64(0)
+	if highestProcessedDAAScore > ipr.lowDAAScore {
+		// Avoid a negative diff
+		relativeDAAScore = highestProcessedDAAScore - ipr.lowDAAScore
+	}
+	progressPercent := int((float64(relativeDAAScore) / float64(ipr.totalDAAScoreDifference)) * 100)
+	if progressPercent > ipr.lastReportedProgressPercent {
+		log.Infof("IBD: Processed %d %s (%d%%)", ipr.processed, ipr.objectName, progressPercent)
+		ipr.lastReportedProgressPercent = progressPercent
+	}
+}

app/protocol/flows/v5/blockrelay/ibd_with_headers_proof.go

@@ -0,0 +1,428 @@
+package blockrelay
+
+import (
+	"fmt"
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/common"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/domain/consensus/ruleerrors"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/consensushashing"
+	"github.com/pkg/errors"
+	"time"
+)
+
+func (flow *handleIBDFlow) ibdWithHeadersProof(
+	syncerHeaderSelectedTipHash, relayBlockHash *externalapi.DomainHash, highBlockDAAScore uint64) error {
+	err := flow.Domain().InitStagingConsensus()
+	if err != nil {
+		return err
+	}
+
+	err = flow.downloadHeadersAndPruningUTXOSet(syncerHeaderSelectedTipHash, relayBlockHash, highBlockDAAScore)
+	if err != nil {
+		if !flow.IsRecoverableError(err) {
+			return err
+		}
+
+		log.Infof("IBD with pruning proof from %s was unsuccessful. Deleting the staging consensus.", flow.peer)
+		deleteStagingConsensusErr := flow.Domain().DeleteStagingConsensus()
+		if deleteStagingConsensusErr != nil {
+			return deleteStagingConsensusErr
+		}
+
+		return err
+	}
+
+	log.Infof("Header download stage of IBD with pruning proof completed successfully from %s. "+
+		"Committing the staging consensus and deleting the previous obsolete one if such exists.", flow.peer)
+	err = flow.Domain().CommitStagingConsensus()
+	if err != nil {
+		return err
+	}
+
+	err = flow.OnPruningPointUTXOSetOverride()
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (flow *handleIBDFlow) shouldSyncAndShouldDownloadHeadersProof(
+	relayBlock *externalapi.DomainBlock,
+	highestKnownSyncerChainHash *externalapi.DomainHash) (shouldDownload, shouldSync bool, err error) {
+
+	var highestSharedBlockFound, isPruningPointInSharedBlockChain bool
+	if highestKnownSyncerChainHash != nil {
+		highestSharedBlockFound = true
+		pruningPoint, err := flow.Domain().Consensus().PruningPoint()
+		if err != nil {
+			return false, false, err
+		}
+
+		isPruningPointInSharedBlockChain, err = flow.Domain().Consensus().IsInSelectedParentChainOf(
+			pruningPoint, highestKnownSyncerChainHash)
+		if err != nil {
+			return false, false, err
+		}
+	}
+	// Note: in the case where `highestSharedBlockFound == true && isPruningPointInSharedBlockChain == false`
+	// we might have here info which is relevant to finality conflict decisions. This should be taken into
+	// account when we improve this aspect.
+	if !highestSharedBlockFound || !isPruningPointInSharedBlockChain {
+		hasMoreBlueWorkThanSelectedTipAndPruningDepthMoreBlueScore, err := flow.checkIfHighHashHasMoreBlueWorkThanSelectedTipAndPruningDepthMoreBlueScore(relayBlock)
+		if err != nil {
+			return false, false, err
+		}
+
+		if hasMoreBlueWorkThanSelectedTipAndPruningDepthMoreBlueScore {
+			return true, true, nil
+		}
+
+		return false, false, nil
+	}
+
+	return false, true, nil
+}
+
+func (flow *handleIBDFlow) checkIfHighHashHasMoreBlueWorkThanSelectedTipAndPruningDepthMoreBlueScore(relayBlock *externalapi.DomainBlock) (bool, error) {
+	headersSelectedTip, err := flow.Domain().Consensus().GetHeadersSelectedTip()
+	if err != nil {
+		return false, err
+	}
+
+	headersSelectedTipInfo, err := flow.Domain().Consensus().GetBlockInfo(headersSelectedTip)
+	if err != nil {
+		return false, err
+	}
+
+	if relayBlock.Header.BlueScore() < headersSelectedTipInfo.BlueScore+flow.Config().NetParams().PruningDepth() {
+		return false, nil
+	}
+
+	return relayBlock.Header.BlueWork().Cmp(headersSelectedTipInfo.BlueWork) > 0, nil
+}
+
+func (flow *handleIBDFlow) syncAndValidatePruningPointProof() (*externalapi.DomainHash, error) {
+	log.Infof("Downloading the pruning point proof from %s", flow.peer)
+	err := flow.outgoingRoute.Enqueue(appmessage.NewMsgRequestPruningPointProof())
+	if err != nil {
+		return nil, err
+	}
+	message, err := flow.incomingRoute.DequeueWithTimeout(10 * time.Minute)
+	if err != nil {
+		return nil, err
+	}
+	pruningPointProofMessage, ok := message.(*appmessage.MsgPruningPointProof)
+	if !ok {
+		return nil, protocolerrors.Errorf(true, "received unexpected message type. "+
+			"expected: %s, got: %s", appmessage.CmdPruningPointProof, message.Command())
+	}
+	pruningPointProof := appmessage.MsgPruningPointProofToDomainPruningPointProof(pruningPointProofMessage)
+	err = flow.Domain().Consensus().ValidatePruningPointProof(pruningPointProof)
+	if err != nil {
+		if errors.As(err, &ruleerrors.RuleError{}) {
+			return nil, protocolerrors.Wrapf(true, err, "pruning point proof validation failed")
+		}
+		return nil, err
+	}
+
+	err = flow.Domain().StagingConsensus().ApplyPruningPointProof(pruningPointProof)
+	if err != nil {
+		return nil, err
+	}
+
+	return consensushashing.HeaderHash(pruningPointProof.Headers[0][len(pruningPointProof.Headers[0])-1]), nil
+}
+
+func (flow *handleIBDFlow) downloadHeadersAndPruningUTXOSet(
+	syncerHeaderSelectedTipHash, relayBlockHash *externalapi.DomainHash,
+	highBlockDAAScore uint64) error {
+
+	proofPruningPoint, err := flow.syncAndValidatePruningPointProof()
+	if err != nil {
+		return err
+	}
+
+	err = flow.syncPruningPointsAndPruningPointAnticone(proofPruningPoint)
+	if err != nil {
+		return err
+	}
+
+	// TODO: Remove this condition once there's more proper way to check finality violation
+	// in the headers proof.
+	if proofPruningPoint.Equal(flow.Config().NetParams().GenesisHash) {
+		return protocolerrors.Errorf(true, "the genesis pruning point violates finality")
+	}
+
+	err = flow.syncPruningPointFutureHeaders(flow.Domain().StagingConsensus(),
+		syncerHeaderSelectedTipHash, proofPruningPoint, relayBlockHash, highBlockDAAScore)
+	if err != nil {
+		return err
+	}
+
+	log.Infof("Headers downloaded from peer %s", flow.peer)
+
+	relayBlockInfo, err := flow.Domain().StagingConsensus().GetBlockInfo(relayBlockHash)
+	if err != nil {
+		return err
+	}
+
+	if !relayBlockInfo.Exists {
+		return protocolerrors.Errorf(true, "the triggering IBD block was not sent")
+	}
+
+	err = flow.validatePruningPointFutureHeaderTimestamps()
+	if err != nil {
+		return err
+	}
+
+	log.Debugf("Syncing the current pruning point UTXO set")
+	syncedPruningPointUTXOSetSuccessfully, err := flow.syncPruningPointUTXOSet(flow.Domain().StagingConsensus(), proofPruningPoint)
+	if err != nil {
+		return err
+	}
+	if !syncedPruningPointUTXOSetSuccessfully {
+		log.Debugf("Aborting IBD because the pruning point UTXO set failed to sync")
+		return nil
+	}
+	log.Debugf("Finished syncing the current pruning point UTXO set")
+	return nil
+}
+
+func (flow *handleIBDFlow) syncPruningPointsAndPruningPointAnticone(proofPruningPoint *externalapi.DomainHash) error {
+	log.Infof("Downloading the past pruning points and the pruning point anticone from %s", flow.peer)
+	err := flow.outgoingRoute.Enqueue(appmessage.NewMsgRequestPruningPointAndItsAnticone())
+	if err != nil {
+		return err
+	}
+
+	err = flow.validateAndInsertPruningPoints(proofPruningPoint)
+	if err != nil {
+		return err
+	}
+
+	message, err := flow.incomingRoute.DequeueWithTimeout(common.DefaultTimeout)
+	if err != nil {
+		return err
+	}
+
+	msgTrustedData, ok := message.(*appmessage.MsgTrustedData)
+	if !ok {
+		return protocolerrors.Errorf(true, "received unexpected message type. "+
+			"expected: %s, got: %s", appmessage.CmdTrustedData, message.Command())
+	}
+
+	pruningPointWithMetaData, done, err := flow.receiveBlockWithTrustedData()
+	if err != nil {
+		return err
+	}
+
+	if done {
+		return protocolerrors.Errorf(true, "got `done` message before receiving the pruning point")
+	}
+
+	if !pruningPointWithMetaData.Block.Header.BlockHash().Equal(proofPruningPoint) {
+		return protocolerrors.Errorf(true, "first block with trusted data is not the pruning point")
+	}
+
+	err = flow.processBlockWithTrustedData(flow.Domain().StagingConsensus(), pruningPointWithMetaData, msgTrustedData)
+	if err != nil {
+		return err
+	}
+
+	i := 0
+	for ; ; i++ {
+		blockWithTrustedData, done, err := flow.receiveBlockWithTrustedData()
+		if err != nil {
+			return err
+		}
+
+		if done {
+			break
+		}
+
+		err = flow.processBlockWithTrustedData(flow.Domain().StagingConsensus(), blockWithTrustedData, msgTrustedData)
+		if err != nil {
+			return err
+		}
+
+		// We're using i+2 because we want to check if the next block will belong to the next batch, but we already downloaded
+		// the pruning point outside the loop so we use i+2 instead of i+1.
+		if (i+2)%ibdBatchSize == 0 {
+			log.Infof("Downloaded %d blocks from the pruning point anticone", i+1)
+			err := flow.outgoingRoute.Enqueue(appmessage.NewMsgRequestNextPruningPointAndItsAnticoneBlocks())
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	log.Infof("Finished downloading pruning point and its anticone from %s. Total blocks downloaded: %d", flow.peer, i+1)
+	return nil
+}
+
+func (flow *handleIBDFlow) processBlockWithTrustedData(
+	consensus externalapi.Consensus, block *appmessage.MsgBlockWithTrustedDataV4, data *appmessage.MsgTrustedData) error {
+
+	blockWithTrustedData := &externalapi.BlockWithTrustedData{
+		Block:        appmessage.MsgBlockToDomainBlock(block.Block),
+		DAAWindow:    make([]*externalapi.TrustedDataDataDAAHeader, 0, len(block.DAAWindowIndices)),
+		GHOSTDAGData: make([]*externalapi.BlockGHOSTDAGDataHashPair, 0, len(block.GHOSTDAGDataIndices)),
+	}
+
+	for _, index := range block.DAAWindowIndices {
+		blockWithTrustedData.DAAWindow = append(blockWithTrustedData.DAAWindow, appmessage.TrustedDataDataDAABlockV4ToTrustedDataDataDAAHeader(data.DAAWindow[index]))
+	}
+
+	for _, index := range block.GHOSTDAGDataIndices {
+		blockWithTrustedData.GHOSTDAGData = append(blockWithTrustedData.GHOSTDAGData, appmessage.GHOSTDAGHashPairToDomainGHOSTDAGHashPair(data.GHOSTDAGData[index]))
+	}
+
+	_, err := consensus.ValidateAndInsertBlockWithTrustedData(blockWithTrustedData, false)
+	return err
+}
+
+func (flow *handleIBDFlow) receiveBlockWithTrustedData() (*appmessage.MsgBlockWithTrustedDataV4, bool, error) {
+	message, err := flow.incomingRoute.DequeueWithTimeout(common.DefaultTimeout)
+	if err != nil {
+		return nil, false, err
+	}
+
+	switch downCastedMessage := message.(type) {
+	case *appmessage.MsgBlockWithTrustedDataV4:
+		return downCastedMessage, false, nil
+	case *appmessage.MsgDoneBlocksWithTrustedData:
+		return nil, true, nil
+	default:
+		return nil, false,
+			protocolerrors.Errorf(true, "received unexpected message type. "+
+				"expected: %s or %s, got: %s",
+				(&appmessage.MsgBlockWithTrustedData{}).Command(),
+				(&appmessage.MsgDoneBlocksWithTrustedData{}).Command(),
+				downCastedMessage.Command())
+	}
+}
+
+func (flow *handleIBDFlow) receivePruningPoints() (*appmessage.MsgPruningPoints, error) {
+	message, err := flow.incomingRoute.DequeueWithTimeout(common.DefaultTimeout)
+	if err != nil {
+		return nil, err
+	}
+
+	msgPruningPoints, ok := message.(*appmessage.MsgPruningPoints)
+	if !ok {
+		return nil,
+			protocolerrors.Errorf(true, "received unexpected message type. "+
+				"expected: %s, got: %s", appmessage.CmdPruningPoints, message.Command())
+	}
+
+	return msgPruningPoints, nil
+}
+
+func (flow *handleIBDFlow) validateAndInsertPruningPoints(proofPruningPoint *externalapi.DomainHash) error {
+	currentPruningPoint, err := flow.Domain().Consensus().PruningPoint()
+	if err != nil {
+		return err
+	}
+
+	if currentPruningPoint.Equal(proofPruningPoint) {
+		return protocolerrors.Errorf(true, "the proposed pruning point is the same as the current pruning point")
+	}
+
+	pruningPoints, err := flow.receivePruningPoints()
+	if err != nil {
+		return err
+	}
+
+	headers := make([]externalapi.BlockHeader, len(pruningPoints.Headers))
+	for i, header := range pruningPoints.Headers {
+		headers[i] = appmessage.BlockHeaderToDomainBlockHeader(header)
+	}
+
+	arePruningPointsViolatingFinality, err := flow.Domain().Consensus().ArePruningPointsViolatingFinality(headers)
+	if err != nil {
+		return err
+	}
+
+	if arePruningPointsViolatingFinality {
+		// TODO: Find a better way to deal with finality conflicts.
+		return protocolerrors.Errorf(false, "pruning points are violating finality")
+	}
+
+	lastPruningPoint := consensushashing.HeaderHash(headers[len(headers)-1])
+	if !lastPruningPoint.Equal(proofPruningPoint) {
+		return protocolerrors.Errorf(true, "the proof pruning point is not equal to the last pruning "+
+			"point in the list")
+	}
+
+	err = flow.Domain().StagingConsensus().ImportPruningPoints(headers)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (flow *handleIBDFlow) syncPruningPointUTXOSet(consensus externalapi.Consensus,
+	pruningPoint *externalapi.DomainHash) (bool, error) {
+
+	log.Infof("Checking if the suggested pruning point %s is compatible to the node DAG", pruningPoint)
+	isValid, err := flow.Domain().StagingConsensus().IsValidPruningPoint(pruningPoint)
+	if err != nil {
+		return false, err
+	}
+
+	if !isValid {
+		return false, protocolerrors.Errorf(true, "invalid pruning point %s", pruningPoint)
+	}
+
+	log.Info("Fetching the pruning point UTXO set")
+	isSuccessful, err := flow.fetchMissingUTXOSet(consensus, pruningPoint)
+	if err != nil {
+		log.Infof("An error occurred while fetching the pruning point UTXO set. Stopping IBD. (%s)", err)
+		return false, err
+	}
+
+	if !isSuccessful {
+		log.Infof("Couldn't successfully fetch the pruning point UTXO set. Stopping IBD.")
+		return false, nil
+	}
+
+	log.Info("Fetched the new pruning point UTXO set")
+	return true, nil
+}
+
+func (flow *handleIBDFlow) fetchMissingUTXOSet(consensus externalapi.Consensus, pruningPointHash *externalapi.DomainHash) (succeed bool, err error) {
+	defer func() {
+		err := flow.Domain().StagingConsensus().ClearImportedPruningPointData()
+		if err != nil {
+			panic(fmt.Sprintf("failed to clear imported pruning point data: %s", err))
+		}
+	}()
+
+	err = flow.outgoingRoute.Enqueue(appmessage.NewMsgRequestPruningPointUTXOSet(pruningPointHash))
+	if err != nil {
+		return false, err
+	}
+
+	receivedAll, err := flow.receiveAndInsertPruningPointUTXOSet(consensus, pruningPointHash)
+	if err != nil {
+		return false, err
+	}
+	if !receivedAll {
+		return false, nil
+	}
+
+	err = flow.Domain().StagingConsensus().ValidateAndInsertImportedPruningPoint(pruningPointHash)
+	if err != nil {
+		// TODO: Find a better way to deal with finality conflicts.
+		if errors.Is(err, ruleerrors.ErrSuggestedPruningViolatesFinality) {
+			return false, nil
+		}
+		return false, protocolerrors.ConvertToBanningProtocolErrorIfRuleError(err, "error with pruning point UTXO set")
+	}
+
+	return true, nil
+}

app/protocol/flows/v5/blockrelay/log.go

@@ -0,0 +1,9 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/infrastructure/logger"
+	"github.com/kaspanet/kaspad/util/panics"
+)
+
+var log = logger.RegisterSubSystem("PROT")
+var spawn = panics.GoroutineWrapperFunc(log)

app/protocol/flows/v5/blockrelay/send_virtual_selected_parent_inv.go

@@ -0,0 +1,35 @@
+package blockrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	peerpkg "github.com/kaspanet/kaspad/app/protocol/peer"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/infrastructure/config"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+// SendVirtualSelectedParentInvContext is the interface for the context needed for the SendVirtualSelectedParentInv flow.
+type SendVirtualSelectedParentInvContext interface {
+	Domain() domain.Domain
+	Config() *config.Config
+}
+
+// SendVirtualSelectedParentInv sends a peer the selected parent hash of the virtual
+func SendVirtualSelectedParentInv(context SendVirtualSelectedParentInvContext,
+	outgoingRoute *router.Route, peer *peerpkg.Peer) error {
+
+	virtualSelectedParent, err := context.Domain().Consensus().GetVirtualSelectedParent()
+	if err != nil {
+		return err
+	}
+
+	if virtualSelectedParent.Equal(context.Config().NetParams().GenesisHash) {
+		log.Debugf("Skipping sending the virtual selected parent hash to peer %s because it's the genesis", peer)
+		return nil
+	}
+
+	log.Debugf("Sending virtual selected parent hash %s to peer %s", virtualSelectedParent, peer)
+
+	virtualSelectedParentInv := appmessage.NewMsgInvBlock(virtualSelectedParent)
+	return outgoingRoute.Enqueue(virtualSelectedParentInv)
+}

app/protocol/flows/v5/ping/receive.go

@@ -0,0 +1,42 @@
+package ping
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+// ReceivePingsContext is the interface for the context needed for the ReceivePings flow.
+type ReceivePingsContext interface {
+}
+
+type receivePingsFlow struct {
+	ReceivePingsContext
+	incomingRoute, outgoingRoute *router.Route
+}
+
+// ReceivePings handles all ping messages coming through incomingRoute.
+// This function assumes that incomingRoute will only return MsgPing.
+func ReceivePings(context ReceivePingsContext, incomingRoute *router.Route, outgoingRoute *router.Route) error {
+	flow := &receivePingsFlow{
+		ReceivePingsContext: context,
+		incomingRoute:       incomingRoute,
+		outgoingRoute:       outgoingRoute,
+	}
+	return flow.start()
+}
+
+func (flow *receivePingsFlow) start() error {
+	for {
+		message, err := flow.incomingRoute.Dequeue()
+		if err != nil {
+			return err
+		}
+		pingMessage := message.(*appmessage.MsgPing)
+
+		pongMessage := appmessage.NewMsgPong(pingMessage.Nonce)
+		err = flow.outgoingRoute.Enqueue(pongMessage)
+		if err != nil {
+			return err
+		}
+	}
+}

app/protocol/flows/v5/ping/send.go

@@ -0,0 +1,77 @@
+package ping
+
+import (
+	"github.com/kaspanet/kaspad/app/protocol/common"
+	"github.com/kaspanet/kaspad/app/protocol/flowcontext"
+	"github.com/pkg/errors"
+	"time"
+
+	"github.com/kaspanet/kaspad/app/appmessage"
+	peerpkg "github.com/kaspanet/kaspad/app/protocol/peer"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"github.com/kaspanet/kaspad/util/random"
+)
+
+// SendPingsContext is the interface for the context needed for the SendPings flow.
+type SendPingsContext interface {
+	ShutdownChan() <-chan struct{}
+}
+
+type sendPingsFlow struct {
+	SendPingsContext
+	incomingRoute, outgoingRoute *router.Route
+	peer                         *peerpkg.Peer
+}
+
+// SendPings starts sending MsgPings every pingInterval seconds to the
+// given peer.
+// This function assumes that incomingRoute will only return MsgPong.
+func SendPings(context SendPingsContext, incomingRoute *router.Route, outgoingRoute *router.Route, peer *peerpkg.Peer) error {
+	flow := &sendPingsFlow{
+		SendPingsContext: context,
+		incomingRoute:    incomingRoute,
+		outgoingRoute:    outgoingRoute,
+		peer:             peer,
+	}
+	return flow.start()
+}
+
+func (flow *sendPingsFlow) start() error {
+	const pingInterval = 2 * time.Minute
+	ticker := time.NewTicker(pingInterval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-flow.ShutdownChan():
+			return nil
+		case <-ticker.C:
+		}
+
+		nonce, err := random.Uint64()
+		if err != nil {
+			return err
+		}
+		flow.peer.SetPingPending(nonce)
+
+		pingMessage := appmessage.NewMsgPing(nonce)
+		err = flow.outgoingRoute.Enqueue(pingMessage)
+		if err != nil {
+			return err
+		}
+
+		message, err := flow.incomingRoute.DequeueWithTimeout(common.DefaultTimeout)
+		if err != nil {
+			if errors.Is(err, router.ErrTimeout) {
+				return errors.Wrapf(flowcontext.ErrPingTimeout, err.Error())
+			}
+			return err
+		}
+		pongMessage := message.(*appmessage.MsgPong)
+		if pongMessage.Nonce != pingMessage.Nonce {
+			return protocolerrors.New(true, "nonce mismatch between ping and pong")
+		}
+		flow.peer.SetPingIdle()
+	}
+}

app/protocol/flows/v5/register.go

@@ -0,0 +1,209 @@
+package v5
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/common"
+	"github.com/kaspanet/kaspad/app/protocol/flowcontext"
+	"github.com/kaspanet/kaspad/app/protocol/flows/v5/addressexchange"
+	"github.com/kaspanet/kaspad/app/protocol/flows/v5/blockrelay"
+	"github.com/kaspanet/kaspad/app/protocol/flows/v5/ping"
+	"github.com/kaspanet/kaspad/app/protocol/flows/v5/rejects"
+	"github.com/kaspanet/kaspad/app/protocol/flows/v5/transactionrelay"
+	peerpkg "github.com/kaspanet/kaspad/app/protocol/peer"
+	routerpkg "github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+type protocolManager interface {
+	RegisterFlow(name string, router *routerpkg.Router, messageTypes []appmessage.MessageCommand, isStopping *uint32,
+		errChan chan error, initializeFunc common.FlowInitializeFunc) *common.Flow
+	RegisterOneTimeFlow(name string, router *routerpkg.Router, messageTypes []appmessage.MessageCommand,
+		isStopping *uint32, stopChan chan error, initializeFunc common.FlowInitializeFunc) *common.Flow
+	RegisterFlowWithCapacity(name string, capacity int, router *routerpkg.Router,
+		messageTypes []appmessage.MessageCommand, isStopping *uint32,
+		errChan chan error, initializeFunc common.FlowInitializeFunc) *common.Flow
+	Context() *flowcontext.FlowContext
+}
+
+// Register is used in order to register all the protocol flows to the given router.
+func Register(m protocolManager, router *routerpkg.Router, errChan chan error, isStopping *uint32) (flows []*common.Flow) {
+	flows = registerAddressFlows(m, router, isStopping, errChan)
+	flows = append(flows, registerBlockRelayFlows(m, router, isStopping, errChan)...)
+	flows = append(flows, registerPingFlows(m, router, isStopping, errChan)...)
+	flows = append(flows, registerTransactionRelayFlow(m, router, isStopping, errChan)...)
+	flows = append(flows, registerRejectsFlow(m, router, isStopping, errChan)...)
+
+	return flows
+}
+
+func registerAddressFlows(m protocolManager, router *routerpkg.Router, isStopping *uint32, errChan chan error) []*common.Flow {
+	outgoingRoute := router.OutgoingRoute()
+
+	return []*common.Flow{
+		m.RegisterFlow("SendAddresses", router, []appmessage.MessageCommand{appmessage.CmdRequestAddresses}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return addressexchange.SendAddresses(m.Context(), incomingRoute, outgoingRoute)
+			},
+		),
+
+		m.RegisterOneTimeFlow("ReceiveAddresses", router, []appmessage.MessageCommand{appmessage.CmdAddresses}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return addressexchange.ReceiveAddresses(m.Context(), incomingRoute, outgoingRoute, peer)
+			},
+		),
+	}
+}
+
+func registerBlockRelayFlows(m protocolManager, router *routerpkg.Router, isStopping *uint32, errChan chan error) []*common.Flow {
+	outgoingRoute := router.OutgoingRoute()
+
+	return []*common.Flow{
+		m.RegisterOneTimeFlow("SendVirtualSelectedParentInv", router, []appmessage.MessageCommand{},
+			isStopping, errChan, func(route *routerpkg.Route, peer *peerpkg.Peer) error {
+				return blockrelay.SendVirtualSelectedParentInv(m.Context(), outgoingRoute, peer)
+			}),
+
+		m.RegisterFlow("HandleRelayInvs", router, []appmessage.MessageCommand{
+			appmessage.CmdInvRelayBlock, appmessage.CmdBlock, appmessage.CmdBlockLocator,
+		},
+			isStopping, errChan, func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return blockrelay.HandleRelayInvs(m.Context(), incomingRoute,
+					outgoingRoute, peer)
+			},
+		),
+
+		m.RegisterFlow("HandleIBD", router, []appmessage.MessageCommand{
+			appmessage.CmdDoneHeaders, appmessage.CmdUnexpectedPruningPoint, appmessage.CmdPruningPointUTXOSetChunk,
+			appmessage.CmdBlockHeaders, appmessage.CmdIBDBlockLocatorHighestHash, appmessage.CmdBlockWithTrustedDataV4,
+			appmessage.CmdDoneBlocksWithTrustedData, appmessage.CmdIBDBlockLocatorHighestHashNotFound,
+			appmessage.CmdDonePruningPointUTXOSetChunks, appmessage.CmdIBDBlock, appmessage.CmdPruningPoints,
+			appmessage.CmdPruningPointProof,
+			appmessage.CmdTrustedData,
+			appmessage.CmdIBDChainBlockLocator,
+		},
+			isStopping, errChan, func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return blockrelay.HandleIBD(m.Context(), incomingRoute,
+					outgoingRoute, peer)
+			},
+		),
+
+		m.RegisterFlow("HandleRelayBlockRequests", router, []appmessage.MessageCommand{appmessage.CmdRequestRelayBlocks}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return blockrelay.HandleRelayBlockRequests(m.Context(), incomingRoute, outgoingRoute, peer)
+			},
+		),
+
+		m.RegisterFlow("HandleRequestBlockLocator", router,
+			[]appmessage.MessageCommand{appmessage.CmdRequestBlockLocator}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return blockrelay.HandleRequestBlockLocator(m.Context(), incomingRoute, outgoingRoute)
+			},
+		),
+
+		m.RegisterFlow("HandleRequestHeaders", router,
+			[]appmessage.MessageCommand{appmessage.CmdRequestHeaders, appmessage.CmdRequestNextHeaders}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return blockrelay.HandleRequestHeaders(m.Context(), incomingRoute, outgoingRoute, peer)
+			},
+		),
+
+		m.RegisterFlow("HandleIBDBlockRequests", router,
+			[]appmessage.MessageCommand{appmessage.CmdRequestIBDBlocks}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return blockrelay.HandleIBDBlockRequests(m.Context(), incomingRoute, outgoingRoute)
+			},
+		),
+
+		m.RegisterFlow("HandleRequestPruningPointUTXOSet", router,
+			[]appmessage.MessageCommand{appmessage.CmdRequestPruningPointUTXOSet,
+				appmessage.CmdRequestNextPruningPointUTXOSetChunk}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return blockrelay.HandleRequestPruningPointUTXOSet(m.Context(), incomingRoute, outgoingRoute)
+			},
+		),
+
+		m.RegisterFlow("HandlePruningPointAndItsAnticoneRequests", router,
+			[]appmessage.MessageCommand{appmessage.CmdRequestPruningPointAndItsAnticone, appmessage.CmdRequestNextPruningPointAndItsAnticoneBlocks}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return blockrelay.HandlePruningPointAndItsAnticoneRequests(m.Context(), incomingRoute, outgoingRoute, peer)
+			},
+		),
+
+		m.RegisterFlow("HandleIBDBlockLocator", router,
+			[]appmessage.MessageCommand{appmessage.CmdIBDBlockLocator}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return blockrelay.HandleIBDBlockLocator(m.Context(), incomingRoute, outgoingRoute, peer)
+			},
+		),
+
+		m.RegisterFlow("HandleRequestIBDChainBlockLocator", router,
+			[]appmessage.MessageCommand{appmessage.CmdRequestIBDChainBlockLocator}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return blockrelay.HandleRequestIBDChainBlockLocator(m.Context(), incomingRoute, outgoingRoute)
+			},
+		),
+
+		m.RegisterFlow("HandleRequestAnticone", router,
+			[]appmessage.MessageCommand{appmessage.CmdRequestAnticone}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return blockrelay.HandleRequestAnticone(m.Context(), incomingRoute, outgoingRoute, peer)
+			},
+		),
+
+		m.RegisterFlow("HandlePruningPointProofRequests", router,
+			[]appmessage.MessageCommand{appmessage.CmdRequestPruningPointProof}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return blockrelay.HandlePruningPointProofRequests(m.Context(), incomingRoute, outgoingRoute, peer)
+			},
+		),
+	}
+}
+
+func registerPingFlows(m protocolManager, router *routerpkg.Router, isStopping *uint32, errChan chan error) []*common.Flow {
+	outgoingRoute := router.OutgoingRoute()
+
+	return []*common.Flow{
+		m.RegisterFlow("ReceivePings", router, []appmessage.MessageCommand{appmessage.CmdPing}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return ping.ReceivePings(m.Context(), incomingRoute, outgoingRoute)
+			},
+		),
+
+		m.RegisterFlow("SendPings", router, []appmessage.MessageCommand{appmessage.CmdPong}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return ping.SendPings(m.Context(), incomingRoute, outgoingRoute, peer)
+			},
+		),
+	}
+}
+
+func registerTransactionRelayFlow(m protocolManager, router *routerpkg.Router, isStopping *uint32, errChan chan error) []*common.Flow {
+	outgoingRoute := router.OutgoingRoute()
+
+	return []*common.Flow{
+		m.RegisterFlowWithCapacity("HandleRelayedTransactions", 10_000, router,
+			[]appmessage.MessageCommand{appmessage.CmdInvTransaction, appmessage.CmdTx, appmessage.CmdTransactionNotFound}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return transactionrelay.HandleRelayedTransactions(m.Context(), incomingRoute, outgoingRoute)
+			},
+		),
+		m.RegisterFlow("HandleRequestTransactions", router,
+			[]appmessage.MessageCommand{appmessage.CmdRequestTransactions}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return transactionrelay.HandleRequestedTransactions(m.Context(), incomingRoute, outgoingRoute)
+			},
+		),
+	}
+}
+
+func registerRejectsFlow(m protocolManager, router *routerpkg.Router, isStopping *uint32, errChan chan error) []*common.Flow {
+	outgoingRoute := router.OutgoingRoute()
+
+	return []*common.Flow{
+		m.RegisterFlow("HandleRejects", router,
+			[]appmessage.MessageCommand{appmessage.CmdReject}, isStopping, errChan,
+			func(incomingRoute *routerpkg.Route, peer *peerpkg.Peer) error {
+				return rejects.HandleRejects(m.Context(), incomingRoute, outgoingRoute)
+			},
+		),
+	}
+}

app/protocol/flows/v5/rejects/handle_rejects.go

@@ -0,0 +1,37 @@
+package rejects
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+// HandleRejectsContext is the interface for the context needed for the HandleRejects flow.
+type HandleRejectsContext interface {
+}
+
+type handleRejectsFlow struct {
+	HandleRejectsContext
+	incomingRoute, outgoingRoute *router.Route
+}
+
+// HandleRejects handles all reject messages coming through incomingRoute.
+// This function assumes that incomingRoute will only return MsgReject.
+func HandleRejects(context HandleRejectsContext, incomingRoute *router.Route, outgoingRoute *router.Route) error {
+	flow := &handleRejectsFlow{
+		HandleRejectsContext: context,
+		incomingRoute:        incomingRoute,
+		outgoingRoute:        outgoingRoute,
+	}
+	return flow.start()
+}
+
+func (flow *handleRejectsFlow) start() error {
+	message, err := flow.incomingRoute.Dequeue()
+	if err != nil {
+		return err
+	}
+	rejectMessage := message.(*appmessage.MsgReject)
+
+	return protocolerrors.Errorf(false, "got reject message: `%s`", rejectMessage.Reason)
+}

app/protocol/flows/v5/testing/common_test.go

@@ -0,0 +1,24 @@
+package testing
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/pkg/errors"
+)
+
+func checkFlowError(t *testing.T, err error, isProtocolError bool, shouldBan bool, contains string) {
+	pErr := protocolerrors.ProtocolError{}
+	if errors.As(err, &pErr) != isProtocolError {
+		t.Fatalf("Unexepcted error %+v", err)
+	}
+
+	if pErr.ShouldBan != shouldBan {
+		t.Fatalf("Exepcted shouldBan %t but got %t", shouldBan, pErr.ShouldBan)
+	}
+
+	if !strings.Contains(err.Error(), contains) {
+		t.Fatalf("Unexpected error. Expected error to contain '%s' but got: %+v", contains, err)
+	}
+}

app/protocol/flows/v5/testing/receiveaddresses_test.go

@@ -0,0 +1,51 @@
+package testing
+
+import (
+	"github.com/kaspanet/kaspad/app/protocol/flows/v5/addressexchange"
+	"testing"
+	"time"
+
+	"github.com/kaspanet/kaspad/app/appmessage"
+	peerpkg "github.com/kaspanet/kaspad/app/protocol/peer"
+	"github.com/kaspanet/kaspad/domain/consensus"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/testutils"
+	"github.com/kaspanet/kaspad/infrastructure/network/addressmanager"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+type fakeReceiveAddressesContext struct{}
+
+func (f fakeReceiveAddressesContext) AddressManager() *addressmanager.AddressManager {
+	return nil
+}
+
+func TestReceiveAddressesErrors(t *testing.T) {
+	testutils.ForAllNets(t, true, func(t *testing.T, consensusConfig *consensus.Config) {
+		incomingRoute := router.NewRoute("incoming")
+		outgoingRoute := router.NewRoute("outgoing")
+		peer := peerpkg.New(nil)
+		errChan := make(chan error)
+		go func() {
+			errChan <- addressexchange.ReceiveAddresses(fakeReceiveAddressesContext{}, incomingRoute, outgoingRoute, peer)
+		}()
+
+		_, err := outgoingRoute.DequeueWithTimeout(time.Second)
+		if err != nil {
+			t.Fatalf("DequeueWithTimeout: %+v", err)
+		}
+
+		// Sending addressmanager.GetAddressesMax+1 addresses should trigger a ban
+		err = incomingRoute.Enqueue(appmessage.NewMsgAddresses(make([]*appmessage.NetAddress,
+			addressmanager.GetAddressesMax+1)))
+		if err != nil {
+			t.Fatalf("Enqueue: %+v", err)
+		}
+
+		select {
+		case err := <-errChan:
+			checkFlowError(t, err, true, true, "address count exceeded")
+		case <-time.After(time.Second):
+			t.Fatalf("timed out after %s", time.Second)
+		}
+	})
+}

app/protocol/flows/v5/testing/testing.go

@@ -0,0 +1,4 @@
+package testing
+
+// Because of a bug in Go coverage fails if you have packages with test files only. See https://github.com/golang/go/issues/27333
+// So this is a dummy non-test go file in the package.

app/protocol/flows/v5/transactionrelay/handle_relayed_transactions.go

@@ -0,0 +1,209 @@
+package transactionrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/app/protocol/common"
+	"github.com/kaspanet/kaspad/app/protocol/flowcontext"
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/consensushashing"
+	"github.com/kaspanet/kaspad/domain/miningmanager/mempool"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"github.com/pkg/errors"
+)
+
+// TransactionsRelayContext is the interface for the context needed for the
+// HandleRelayedTransactions and HandleRequestedTransactions flows.
+type TransactionsRelayContext interface {
+	NetAdapter() *netadapter.NetAdapter
+	Domain() domain.Domain
+	SharedRequestedTransactions() *flowcontext.SharedRequestedTransactions
+	OnTransactionAddedToMempool()
+	EnqueueTransactionIDsForPropagation(transactionIDs []*externalapi.DomainTransactionID) error
+	IsIBDRunning() bool
+}
+
+type handleRelayedTransactionsFlow struct {
+	TransactionsRelayContext
+	incomingRoute, outgoingRoute *router.Route
+	invsQueue                    []*appmessage.MsgInvTransaction
+}
+
+// HandleRelayedTransactions listens to appmessage.MsgInvTransaction messages, requests their corresponding transactions if they
+// are missing, adds them to the mempool and propagates them to the rest of the network.
+func HandleRelayedTransactions(context TransactionsRelayContext, incomingRoute *router.Route, outgoingRoute *router.Route) error {
+	flow := &handleRelayedTransactionsFlow{
+		TransactionsRelayContext: context,
+		incomingRoute:            incomingRoute,
+		outgoingRoute:            outgoingRoute,
+		invsQueue:                make([]*appmessage.MsgInvTransaction, 0),
+	}
+	return flow.start()
+}
+
+func (flow *handleRelayedTransactionsFlow) start() error {
+	for {
+		inv, err := flow.readInv()
+		if err != nil {
+			return err
+		}
+
+		if flow.IsIBDRunning() {
+			continue
+		}
+
+		requestedIDs, err := flow.requestInvTransactions(inv)
+		if err != nil {
+			return err
+		}
+
+		err = flow.receiveTransactions(requestedIDs)
+		if err != nil {
+			return err
+		}
+	}
+}
+
+func (flow *handleRelayedTransactionsFlow) requestInvTransactions(
+	inv *appmessage.MsgInvTransaction) (requestedIDs []*externalapi.DomainTransactionID, err error) {
+
+	idsToRequest := make([]*externalapi.DomainTransactionID, 0, len(inv.TxIDs))
+	for _, txID := range inv.TxIDs {
+		if flow.isKnownTransaction(txID) {
+			continue
+		}
+		exists := flow.SharedRequestedTransactions().AddIfNotExists(txID)
+		if exists {
+			continue
+		}
+		idsToRequest = append(idsToRequest, txID)
+	}
+
+	if len(idsToRequest) == 0 {
+		return idsToRequest, nil
+	}
+
+	msgGetTransactions := appmessage.NewMsgRequestTransactions(idsToRequest)
+	err = flow.outgoingRoute.Enqueue(msgGetTransactions)
+	if err != nil {
+		flow.SharedRequestedTransactions().RemoveMany(idsToRequest)
+		return nil, err
+	}
+	return idsToRequest, nil
+}
+
+func (flow *handleRelayedTransactionsFlow) isKnownTransaction(txID *externalapi.DomainTransactionID) bool {
+	// Ask the transaction memory pool if the transaction is known
+	// to it in any form (main pool or orphan).
+	if _, ok := flow.Domain().MiningManager().GetTransaction(txID); ok {
+		return true
+	}
+
+	return false
+}
+
+func (flow *handleRelayedTransactionsFlow) readInv() (*appmessage.MsgInvTransaction, error) {
+	if len(flow.invsQueue) > 0 {
+		var inv *appmessage.MsgInvTransaction
+		inv, flow.invsQueue = flow.invsQueue[0], flow.invsQueue[1:]
+		return inv, nil
+	}
+
+	msg, err := flow.incomingRoute.Dequeue()
+	if err != nil {
+		return nil, err
+	}
+
+	inv, ok := msg.(*appmessage.MsgInvTransaction)
+	if !ok {
+		return nil, protocolerrors.Errorf(true, "unexpected %s message in the block relay flow while "+
+			"expecting an inv message", msg.Command())
+	}
+	return inv, nil
+}
+
+func (flow *handleRelayedTransactionsFlow) broadcastAcceptedTransactions(acceptedTxIDs []*externalapi.DomainTransactionID) error {
+	return flow.EnqueueTransactionIDsForPropagation(acceptedTxIDs)
+}
+
+// readMsgTxOrNotFound returns the next msgTx or msgTransactionNotFound in incomingRoute,
+// returning only one of the message types at a time.
+//
+// and populates invsQueue with any inv messages that meanwhile arrive.
+func (flow *handleRelayedTransactionsFlow) readMsgTxOrNotFound() (
+	msgTx *appmessage.MsgTx, msgNotFound *appmessage.MsgTransactionNotFound, err error) {
+
+	for {
+		message, err := flow.incomingRoute.DequeueWithTimeout(common.DefaultTimeout)
+		if err != nil {
+			return nil, nil, err
+		}
+
+		switch message := message.(type) {
+		case *appmessage.MsgInvTransaction:
+			flow.invsQueue = append(flow.invsQueue, message)
+		case *appmessage.MsgTx:
+			return message, nil, nil
+		case *appmessage.MsgTransactionNotFound:
+			return nil, message, nil
+		default:
+			return nil, nil, errors.Errorf("unexpected message %s", message.Command())
+		}
+	}
+}
+
+func (flow *handleRelayedTransactionsFlow) receiveTransactions(requestedTransactions []*externalapi.DomainTransactionID) error {
+	// In case the function returns earlier than expected, we want to make sure sharedRequestedTransactions is
+	// clean from any pending transactions.
+	defer flow.SharedRequestedTransactions().RemoveMany(requestedTransactions)
+	for _, expectedID := range requestedTransactions {
+		msgTx, msgTxNotFound, err := flow.readMsgTxOrNotFound()
+		if err != nil {
+			return err
+		}
+		if msgTxNotFound != nil {
+			if !msgTxNotFound.ID.Equal(expectedID) {
+				return protocolerrors.Errorf(true, "expected transaction %s, but got %s",
+					expectedID, msgTxNotFound.ID)
+			}
+
+			continue
+		}
+		tx := appmessage.MsgTxToDomainTransaction(msgTx)
+		txID := consensushashing.TransactionID(tx)
+		if !txID.Equal(expectedID) {
+			return protocolerrors.Errorf(true, "expected transaction %s, but got %s",
+				expectedID, txID)
+		}
+
+		acceptedTransactions, err :=
+			flow.Domain().MiningManager().ValidateAndInsertTransaction(tx, false, true)
+		if err != nil {
+			ruleErr := &mempool.RuleError{}
+			if !errors.As(err, ruleErr) {
+				return errors.Wrapf(err, "failed to process transaction %s", txID)
+			}
+
+			shouldBan := false
+			if txRuleErr := (&mempool.TxRuleError{}); errors.As(ruleErr.Err, txRuleErr) {
+				if txRuleErr.RejectCode == mempool.RejectInvalid {
+					shouldBan = true
+				}
+			}
+
+			if !shouldBan {
+				continue
+			}
+
+			return protocolerrors.Errorf(true, "rejected transaction %s: %s", txID, ruleErr)
+		}
+		err = flow.broadcastAcceptedTransactions(consensushashing.TransactionIDs(acceptedTransactions))
+		if err != nil {
+			return err
+		}
+		flow.OnTransactionAddedToMempool()
+	}
+	return nil
+}

app/protocol/flows/v5/transactionrelay/handle_relayed_transactions_test.go

@@ -0,0 +1,196 @@
+package transactionrelay_test
+
+import (
+	"errors"
+	"github.com/kaspanet/kaspad/app/protocol/flowcontext"
+	"github.com/kaspanet/kaspad/app/protocol/flows/v5/transactionrelay"
+	"strings"
+	"testing"
+
+	"github.com/kaspanet/kaspad/app/protocol/protocolerrors"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/domain/consensus"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/testutils"
+	"github.com/kaspanet/kaspad/domain/miningmanager/mempool"
+	"github.com/kaspanet/kaspad/infrastructure/logger"
+	"github.com/kaspanet/kaspad/util/panics"
+
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/infrastructure/config"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+type mocTransactionsRelayContext struct {
+	netAdapter                  *netadapter.NetAdapter
+	domain                      domain.Domain
+	sharedRequestedTransactions *flowcontext.SharedRequestedTransactions
+}
+
+func (m *mocTransactionsRelayContext) NetAdapter() *netadapter.NetAdapter {
+	return m.netAdapter
+}
+
+func (m *mocTransactionsRelayContext) Domain() domain.Domain {
+	return m.domain
+}
+
+func (m *mocTransactionsRelayContext) SharedRequestedTransactions() *flowcontext.SharedRequestedTransactions {
+	return m.sharedRequestedTransactions
+}
+
+func (m *mocTransactionsRelayContext) EnqueueTransactionIDsForPropagation(transactionIDs []*externalapi.DomainTransactionID) error {
+	return nil
+}
+
+func (m *mocTransactionsRelayContext) OnTransactionAddedToMempool() {
+}
+
+func (m *mocTransactionsRelayContext) IsIBDRunning() bool {
+	return false
+}
+
+// TestHandleRelayedTransactionsNotFound tests the flow of  HandleRelayedTransactions when the peer doesn't
+// have the requested transactions in the mempool.
+func TestHandleRelayedTransactionsNotFound(t *testing.T) {
+	testutils.ForAllNets(t, true, func(t *testing.T, consensusConfig *consensus.Config) {
+
+		var log = logger.RegisterSubSystem("PROT")
+		var spawn = panics.GoroutineWrapperFunc(log)
+		factory := consensus.NewFactory()
+		tc, teardown, err := factory.NewTestConsensus(consensusConfig, "TestHandleRelayedTransactionsNotFound")
+		if err != nil {
+			t.Fatalf("Error setting up test consensus: %+v", err)
+		}
+		defer teardown(false)
+
+		sharedRequestedTransactions := flowcontext.NewSharedRequestedTransactions()
+		adapter, err := netadapter.NewNetAdapter(config.DefaultConfig())
+		if err != nil {
+			t.Fatalf("Failed to create a NetAdapter: %v", err)
+		}
+		domainInstance, err := domain.New(consensusConfig, mempool.DefaultConfig(&consensusConfig.Params), tc.Database())
+		if err != nil {
+			t.Fatalf("Failed to set up a domain instance: %v", err)
+		}
+		context := &mocTransactionsRelayContext{
+			netAdapter:                  adapter,
+			domain:                      domainInstance,
+			sharedRequestedTransactions: sharedRequestedTransactions,
+		}
+		incomingRoute := router.NewRoute("incoming")
+		defer incomingRoute.Close()
+		peerIncomingRoute := router.NewRoute("outgoing")
+		defer peerIncomingRoute.Close()
+
+		txID1 := externalapi.NewDomainTransactionIDFromByteArray(&[externalapi.DomainHashSize]byte{
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01})
+		txID2 := externalapi.NewDomainTransactionIDFromByteArray(&[externalapi.DomainHashSize]byte{
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02})
+		txIDs := []*externalapi.DomainTransactionID{txID1, txID2}
+		invMessage := appmessage.NewMsgInvTransaction(txIDs)
+		err = incomingRoute.Enqueue(invMessage)
+		if err != nil {
+			t.Fatalf("Unexpected error from incomingRoute.Enqueue: %v", err)
+		}
+		// The goroutine is representing the peer's actions.
+		spawn("peerResponseToTheTransactionsRequest", func() {
+			msg, err := peerIncomingRoute.Dequeue()
+			if err != nil {
+				t.Fatalf("Dequeue: %v", err)
+			}
+			inv := msg.(*appmessage.MsgRequestTransactions)
+
+			if len(txIDs) != len(inv.IDs) {
+				t.Fatalf("TestHandleRelayedTransactions: expected %d transactions ID, but got %d", len(txIDs), len(inv.IDs))
+			}
+
+			for i, id := range inv.IDs {
+				if txIDs[i].String() != id.String() {
+					t.Fatalf("TestHandleRelayedTransactions: expected equal txID: expected %s, but got %s", txIDs[i].String(), id.String())
+				}
+				err = incomingRoute.Enqueue(appmessage.NewMsgTransactionNotFound(txIDs[i]))
+				if err != nil {
+					t.Fatalf("Unexpected error from incomingRoute.Enqueue: %v", err)
+				}
+			}
+			// Insert an unexpected message type to stop the infinity loop.
+			err = incomingRoute.Enqueue(&appmessage.MsgAddresses{})
+			if err != nil {
+				t.Fatalf("Unexpected error from incomingRoute.Enqueue: %v", err)
+			}
+		})
+
+		err = transactionrelay.HandleRelayedTransactions(context, incomingRoute, peerIncomingRoute)
+		// Since we inserted an unexpected message type to stop the infinity loop,
+		// we expect the error will be infected from this specific message and also the
+		// error will count as a protocol message.
+		if protocolErr := (protocolerrors.ProtocolError{}); err == nil || !errors.As(err, &protocolErr) {
+			t.Fatalf("Expected to protocol error")
+		} else {
+			if !protocolErr.ShouldBan {
+				t.Fatalf("Exepcted shouldBan true, but got false.")
+			}
+			if !strings.Contains(err.Error(), "unexpected Addresses [code 3] message in the block relay flow while expecting an inv message") {
+				t.Fatalf("Unexpected error: expected: an error due to existence of an Addresses message "+
+					"in the block relay flow, but got: %v", protocolErr.Cause)
+			}
+		}
+	})
+}
+
+// TestOnClosedIncomingRoute verifies that an appropriate error message will be returned when
+// trying to dequeue a message from a closed route.
+func TestOnClosedIncomingRoute(t *testing.T) {
+	testutils.ForAllNets(t, true, func(t *testing.T, consensusConfig *consensus.Config) {
+
+		factory := consensus.NewFactory()
+		tc, teardown, err := factory.NewTestConsensus(consensusConfig, "TestOnClosedIncomingRoute")
+		if err != nil {
+			t.Fatalf("Error setting up test consensus: %+v", err)
+		}
+		defer teardown(false)
+
+		sharedRequestedTransactions := flowcontext.NewSharedRequestedTransactions()
+		adapter, err := netadapter.NewNetAdapter(config.DefaultConfig())
+		if err != nil {
+			t.Fatalf("Failed to creat a NetAdapter : %v", err)
+		}
+		domainInstance, err := domain.New(consensusConfig, mempool.DefaultConfig(&consensusConfig.Params), tc.Database())
+		if err != nil {
+			t.Fatalf("Failed to set up a domain instance: %v", err)
+		}
+		context := &mocTransactionsRelayContext{
+			netAdapter:                  adapter,
+			domain:                      domainInstance,
+			sharedRequestedTransactions: sharedRequestedTransactions,
+		}
+		incomingRoute := router.NewRoute("incoming")
+		outgoingRoute := router.NewRoute("outgoing")
+		defer outgoingRoute.Close()
+
+		txID := externalapi.NewDomainTransactionIDFromByteArray(&[externalapi.DomainHashSize]byte{
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01})
+		txIDs := []*externalapi.DomainTransactionID{txID}
+
+		err = incomingRoute.Enqueue(&appmessage.MsgInvTransaction{TxIDs: txIDs})
+		if err != nil {
+			t.Fatalf("Unexpected error from incomingRoute.Enqueue: %v", err)
+		}
+		incomingRoute.Close()
+		err = transactionrelay.HandleRelayedTransactions(context, incomingRoute, outgoingRoute)
+		if err == nil || !errors.Is(err, router.ErrRouteClosed) {
+			t.Fatalf("Unexpected error: expected: %v, got : %v", router.ErrRouteClosed, err)
+		}
+	})
+}

app/protocol/flows/v5/transactionrelay/handle_requested_transactions.go

@@ -0,0 +1,59 @@
+package transactionrelay
+
+import (
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+)
+
+type handleRequestedTransactionsFlow struct {
+	TransactionsRelayContext
+	incomingRoute, outgoingRoute *router.Route
+}
+
+// HandleRequestedTransactions listens to appmessage.MsgRequestTransactions messages, responding with the requested
+// transactions if those are in the mempool.
+// Missing transactions would be ignored
+func HandleRequestedTransactions(context TransactionsRelayContext, incomingRoute *router.Route, outgoingRoute *router.Route) error {
+	flow := &handleRequestedTransactionsFlow{
+		TransactionsRelayContext: context,
+		incomingRoute:            incomingRoute,
+		outgoingRoute:            outgoingRoute,
+	}
+	return flow.start()
+}
+
+func (flow *handleRequestedTransactionsFlow) start() error {
+	for {
+		msgRequestTransactions, err := flow.readRequestTransactions()
+		if err != nil {
+			return err
+		}
+
+		for _, transactionID := range msgRequestTransactions.IDs {
+			tx, ok := flow.Domain().MiningManager().GetTransaction(transactionID)
+
+			if !ok {
+				msgTransactionNotFound := appmessage.NewMsgTransactionNotFound(transactionID)
+				err := flow.outgoingRoute.Enqueue(msgTransactionNotFound)
+				if err != nil {
+					return err
+				}
+				continue
+			}
+
+			err := flow.outgoingRoute.Enqueue(appmessage.DomainTransactionToMsgTx(tx))
+			if err != nil {
+				return err
+			}
+		}
+	}
+}
+
+func (flow *handleRequestedTransactionsFlow) readRequestTransactions() (*appmessage.MsgRequestTransactions, error) {
+	msg, err := flow.incomingRoute.Dequeue()
+	if err != nil {
+		return nil, err
+	}
+
+	return msg.(*appmessage.MsgRequestTransactions), nil
+}

app/protocol/flows/v5/transactionrelay/handle_requested_transactions_test.go

@@ -0,0 +1,91 @@
+package transactionrelay_test
+
+import (
+	"github.com/kaspanet/kaspad/app/protocol/flowcontext"
+	"github.com/kaspanet/kaspad/app/protocol/flows/v5/transactionrelay"
+	"testing"
+
+	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/domain"
+	"github.com/kaspanet/kaspad/domain/consensus"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/testutils"
+	"github.com/kaspanet/kaspad/domain/miningmanager/mempool"
+	"github.com/kaspanet/kaspad/infrastructure/config"
+	"github.com/kaspanet/kaspad/infrastructure/logger"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter"
+	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"github.com/kaspanet/kaspad/util/panics"
+	"github.com/pkg/errors"
+)
+
+// TestHandleRequestedTransactionsNotFound tests the flow of  HandleRequestedTransactions
+// when the requested transactions don't found in the mempool.
+func TestHandleRequestedTransactionsNotFound(t *testing.T) {
+	testutils.ForAllNets(t, true, func(t *testing.T, consensusConfig *consensus.Config) {
+		var log = logger.RegisterSubSystem("PROT")
+		var spawn = panics.GoroutineWrapperFunc(log)
+		factory := consensus.NewFactory()
+		tc, teardown, err := factory.NewTestConsensus(consensusConfig, "TestHandleRequestedTransactionsNotFound")
+		if err != nil {
+			t.Fatalf("Error setting up test Consensus: %+v", err)
+		}
+		defer teardown(false)
+
+		sharedRequestedTransactions := flowcontext.NewSharedRequestedTransactions()
+		adapter, err := netadapter.NewNetAdapter(config.DefaultConfig())
+		if err != nil {
+			t.Fatalf("Failed to create a NetAdapter: %v", err)
+		}
+		domainInstance, err := domain.New(consensusConfig, mempool.DefaultConfig(&consensusConfig.Params), tc.Database())
+		if err != nil {
+			t.Fatalf("Failed to set up a domain Instance: %v", err)
+		}
+		context := &mocTransactionsRelayContext{
+			netAdapter:                  adapter,
+			domain:                      domainInstance,
+			sharedRequestedTransactions: sharedRequestedTransactions,
+		}
+		incomingRoute := router.NewRoute("incoming")
+		outgoingRoute := router.NewRoute("outgoing")
+		defer outgoingRoute.Close()
+
+		txID1 := externalapi.NewDomainTransactionIDFromByteArray(&[externalapi.DomainHashSize]byte{
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01})
+		txID2 := externalapi.NewDomainTransactionIDFromByteArray(&[externalapi.DomainHashSize]byte{
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02})
+		txIDs := []*externalapi.DomainTransactionID{txID1, txID2}
+		msg := appmessage.NewMsgRequestTransactions(txIDs)
+		err = incomingRoute.Enqueue(msg)
+		if err != nil {
+			t.Fatalf("Unexpected error from incomingRoute.Enqueue: %v", err)
+		}
+		// The goroutine is representing the peer's actions.
+		spawn("peerResponseToTheTransactionsMessages", func() {
+			for i, id := range txIDs {
+				msg, err := outgoingRoute.Dequeue()
+				if err != nil {
+					t.Fatalf("Dequeue: %s", err)
+				}
+				outMsg := msg.(*appmessage.MsgTransactionNotFound)
+				if txIDs[i].String() != outMsg.ID.String() {
+					t.Fatalf("TestHandleRelayedTransactions: expected equal txID: expected %s, but got %s", txIDs[i].String(), id.String())
+				}
+			}
+			// Closed the incomingRoute for stop the infinity loop.
+			incomingRoute.Close()
+		})
+
+		err = transactionrelay.HandleRequestedTransactions(context, incomingRoute, outgoingRoute)
+		// Make sure the error is due to the closed route.
+		if err == nil || !errors.Is(err, router.ErrRouteClosed) {
+			t.Fatalf("Unexpected error: expected: %v, got : %v", router.ErrRouteClosed, err)
+		}
+	})
+}

app/protocol/protocol.go

@@ -4,6 +4,7 @@ import (
 	"github.com/kaspanet/kaspad/app/protocol/common"
 	"github.com/kaspanet/kaspad/app/protocol/flows/ready"
 	v4 "github.com/kaspanet/kaspad/app/protocol/flows/v4"
+	v5 "github.com/kaspanet/kaspad/app/protocol/flows/v5"
 	"sync"
 	"sync/atomic"
 
@@ -78,6 +79,8 @@ func (m *Manager) routerInitializer(router *routerpkg.Router, netConnection *net
 		switch peer.ProtocolVersion() {
 		case 4:
 			flows = v4.Register(m, router, errChan, &isStopping)
+		case 5:
+			flows = v5.Register(m, router, errChan, &isStopping)
 		default:
 			panic(errors.Errorf("no way to handle protocol version %d", peer.ProtocolVersion()))
 		}

app/rpc/rpccontext/verbosedata.go

@@ -56,21 +56,29 @@ func (ctx *Context) PopulateBlockWithVerboseData(block *appmessage.RPCBlock, dom
 			"invalid block")
 	}
 
-	_, selectedParentHash, childrenHashes, err := ctx.Domain.Consensus().GetBlockRelations(blockHash)
+	_, childrenHashes, err := ctx.Domain.Consensus().GetBlockRelations(blockHash)
+	if err != nil {
+		return err
+	}
+
+	isChainBlock, err := ctx.Domain.Consensus().IsChainBlock(blockHash)
 	if err != nil {
 		return err
 	}
 
 	block.VerboseData = &appmessage.RPCBlockVerboseData{
-		Hash:           blockHash.String(),
-		Difficulty:     ctx.GetDifficultyRatio(domainBlockHeader.Bits(), ctx.Config.ActiveNetParams),
-		ChildrenHashes: hashes.ToStrings(childrenHashes),
-		IsHeaderOnly:   blockInfo.BlockStatus == externalapi.StatusHeaderOnly,
-		BlueScore:      blockInfo.BlueScore,
+		Hash:                blockHash.String(),
+		Difficulty:          ctx.GetDifficultyRatio(domainBlockHeader.Bits(), ctx.Config.ActiveNetParams),
+		ChildrenHashes:      hashes.ToStrings(childrenHashes),
+		IsHeaderOnly:        blockInfo.BlockStatus == externalapi.StatusHeaderOnly,
+		BlueScore:           blockInfo.BlueScore,
+		MergeSetBluesHashes: hashes.ToStrings(blockInfo.MergeSetBlues),
+		MergeSetRedsHashes:  hashes.ToStrings(blockInfo.MergeSetReds),
+		IsChainBlock:        isChainBlock,
 	}
 	// selectedParentHash will be nil in the genesis block
-	if selectedParentHash != nil {
-		block.VerboseData.SelectedParentHash = selectedParentHash.String()
+	if blockInfo.SelectedParent != nil {
+		block.VerboseData.SelectedParentHash = blockInfo.SelectedParent.String()
 	}
 
 	if blockInfo.BlockStatus == externalapi.StatusHeaderOnly {

app/rpc/rpchandlers/get_block_template.go

@@ -7,6 +7,7 @@ import (
 	"github.com/kaspanet/kaspad/domain/consensus/utils/txscript"
 	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
 	"github.com/kaspanet/kaspad/util"
+	"github.com/kaspanet/kaspad/version"
 )
 
 // HandleGetBlockTemplate handles the respectively named RPC command
@@ -25,7 +26,7 @@ func HandleGetBlockTemplate(context *rpccontext.Context, _ *router.Router, reque
 		return nil, err
 	}
 
-	coinbaseData := &externalapi.DomainCoinbaseData{ScriptPublicKey: scriptPublicKey}
+	coinbaseData := &externalapi.DomainCoinbaseData{ScriptPublicKey: scriptPublicKey, ExtraData: []byte(version.Version())}
 
 	templateBlock, err := context.Domain.MiningManager().GetBlockTemplate(coinbaseData)
 	if err != nil {

changelog.txt

@@ -1,3 +1,31 @@
+Kaspad v0.11.14 - 2022-03-20
+===========================
+* Fix a bug in the new p2p v5 IBD chain negotiation (#1981)
+
+Kaspad v0.11.13 - 2022-03-16
+===========================
+* Display progress of IBD process in Kaspad logs (#1938, #1939, #1949, #1977)
+* Optimize DB writes during fresh IBD (#1937)
+* Add AllowConnectionToDifferentVersions flag to kaspactl (#1940)
+* Drop support for p2p v3 (#1942)
+* Various transaction processing fixes and workarounds (#1943, #1946, #1971, #1974)
+* Make kaspawallet store the utxos sorted by amount (#1947)
+* Implement a `parse` sub command in the kaspawallet (#1953)
+* Set MaxBlockLevels for non-mainnet networks to 250 (#1952)
+* Add cache to DAA block window (#1948)
+* kaspactl: string slice parser for GetUtxosByAddresses (#1955, first contribution by @icook)
+* Add MergeSet and IsChainBlock to RPC (#1961)
+* Ignore transaction invs during IBD (#1960)
+* Optimize validation of expected header pruning point (#1962)
+* Fix a bug in bounded marge depth validation (#1966)
+* Don't relay blocks in virtual anticone (#1970)
+* Add version to block template to allow tracking of miner's kaspad version (#1967)
+* New p2p version: v5 (#1969)
+* Fix IBD shared past negotiation to be non quadratic also in the worst-case (#1969, p2p v5)
+* Send pruning point anticone in batches (#1973, p2p v5)
+* Cleanup log output mistakes and try to be more clear to the user (#1976, #1978)
+* Apply avoiding IBD logic from patch10 to p2p v4 IBD handling (#1979)
+
 Kaspad v0.11.11 - 2022-01-27
 ===========================
 * Fix for rare consensus bug regarding DAA window order. The bug only affected IBD from scratch and only today (#1934)

cmd/kaspactl/command_parser.go

@@ -3,6 +3,7 @@ package main
 import (
 	"reflect"
 	"strconv"
+	"strings"
 
 	"google.golang.org/protobuf/encoding/protojson"
 	"google.golang.org/protobuf/proto"
@@ -149,12 +150,24 @@ func stringToValue(parameterDesc *parameterDescription, valueStr string) (reflec
 
 		value = pointer.Interface()
 
+	case reflect.Slice:
+		sliceType := parameterDesc.typeof.Elem()
+		if sliceType.Kind() != reflect.String {
+			return reflect.Value{},
+				errors.Errorf("Unsupported slice type '%s' for parameter '%s'",
+					sliceType,
+					parameterDesc.name)
+		}
+		if valueStr == "" {
+			value = []string{}
+		} else {
+			value = strings.Split(valueStr, ",")
+		}
 	// Int and uint are not supported because their size is platform-dependant
 	case reflect.Int,
 		reflect.Uint,
 		// Other types are not supported simply because they are not used in any command right now
 		// but support can be added if and when needed
-		reflect.Slice,
 		reflect.Func,
 		reflect.Interface,
 		reflect.Map,

cmd/kaspawallet/config.go

@@ -15,6 +15,7 @@ const (
 	createUnsignedTransactionSubCmd = "create-unsigned-transaction"
 	signSubCmd                      = "sign"
 	broadcastSubCmd                 = "broadcast"
+	parseSubCmd                     = "parse"
 	showAddressesSubCmd             = "show-addresses"
 	newAddressSubCmd                = "new-address"
 	dumpUnencryptedDataSubCmd       = "dump-unencrypted-data"
@@ -79,6 +80,13 @@ type broadcastConfig struct {
 	config.NetworkFlags
 }
 
+type parseConfig struct {
+	Transaction     string `long:"transaction" short:"t" description:"The transaction to parse (encoded in hex)"`
+	TransactionFile string `long:"transaction-file" short:"F" description:"The file containing the transaction to parse (encoded in hex)"`
+	Verbose         bool   `long:"verbose" short:"v" description:"Verbose: show transaction inputs"`
+	config.NetworkFlags
+}
+
 type showAddressesConfig struct {
 	DaemonAddress string `long:"daemonaddress" short:"d" description:"Wallet daemon server to connect to (default: localhost:8082)"`
 	config.NetworkFlags
@@ -133,6 +141,10 @@ func parseCommandLine() (subCommand string, config interface{}) {
 	parser.AddCommand(broadcastSubCmd, "Broadcast the given transaction",
 		"Broadcast the given transaction", broadcastConf)
 
+	parseConf := &parseConfig{}
+	parser.AddCommand(parseSubCmd, "Parse the given transaction and print its contents",
+		"Parse the given transaction and print its contents", parseConf)
+
 	showAddressesConf := &showAddressesConfig{DaemonAddress: defaultListen}
 	parser.AddCommand(showAddressesSubCmd, "Shows all generated public addresses of the current wallet",
 		"Shows all generated public addresses of the current wallet", showAddressesConf)
@@ -207,6 +219,13 @@ func parseCommandLine() (subCommand string, config interface{}) {
 			printErrorAndExit(err)
 		}
 		config = broadcastConf
+	case parseSubCmd:
+		combineNetworkFlags(&parseConf.NetworkFlags, &cfg.NetworkFlags)
+		err := parseConf.ResolveNetwork(parser)
+		if err != nil {
+			printErrorAndExit(err)
+		}
+		config = parseConf
 	case showAddressesSubCmd:
 		combineNetworkFlags(&showAddressesConf.NetworkFlags, &cfg.NetworkFlags)
 		err := showAddressesConf.ResolveNetwork(parser)

cmd/kaspawallet/main.go

@@ -19,6 +19,8 @@ func main() {
 		err = sign(config.(*signConfig))
 	case broadcastSubCmd:
 		err = broadcast(config.(*broadcastConfig))
+	case parseSubCmd:
+		err = parse(config.(*parseConfig))
 	case showAddressesSubCmd:
 		err = showAddresses(config.(*showAddressesConfig))
 	case newAddressSubCmd:

cmd/kaspawallet/parse.go

@@ -0,0 +1,83 @@
+package main
+
+import (
+	"encoding/hex"
+	"fmt"
+	"github.com/kaspanet/kaspad/cmd/kaspawallet/libkaspawallet/serialization"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/consensushashing"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/constants"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/txscript"
+	"github.com/pkg/errors"
+	"io/ioutil"
+	"strings"
+)
+
+func parse(conf *parseConfig) error {
+	if conf.Transaction == "" && conf.TransactionFile == "" {
+		return errors.Errorf("Either --transaction or --transaction-file is required")
+	}
+	if conf.Transaction != "" && conf.TransactionFile != "" {
+		return errors.Errorf("Both --transaction and --transaction-file cannot be passed at the same time")
+	}
+
+	transactionHex := conf.Transaction
+	if conf.TransactionFile != "" {
+		transactionHexBytes, err := ioutil.ReadFile(conf.TransactionFile)
+		if err != nil {
+			return errors.Wrapf(err, "Could not read hex from %s", conf.TransactionFile)
+		}
+		transactionHex = strings.TrimSpace(string(transactionHexBytes))
+	}
+
+	transaction, err := hex.DecodeString(transactionHex)
+	if err != nil {
+		return err
+	}
+
+	partiallySignedTransaction, err := serialization.DeserializePartiallySignedTransaction(transaction)
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("Transaction ID: \t%s\n", consensushashing.TransactionID(partiallySignedTransaction.Tx))
+	fmt.Println()
+
+	allInputSompi := uint64(0)
+	for index, input := range partiallySignedTransaction.Tx.Inputs {
+		partiallySignedInput := partiallySignedTransaction.PartiallySignedInputs[index]
+
+		if conf.Verbose {
+			fmt.Printf("Input %d: \tOutpoint: %s:%d \tAmount: %.2f Kaspa\n", index, input.PreviousOutpoint.TransactionID,
+				input.PreviousOutpoint.Index, float64(partiallySignedInput.PrevOutput.Value)/float64(constants.SompiPerKaspa))
+		}
+
+		allInputSompi += partiallySignedInput.PrevOutput.Value
+	}
+	if conf.Verbose {
+		fmt.Println()
+	}
+
+	allOutputSompi := uint64(0)
+	for index, output := range partiallySignedTransaction.Tx.Outputs {
+		scriptPublicKeyType, scriptPublicKeyAddress, err := txscript.ExtractScriptPubKeyAddress(output.ScriptPublicKey, conf.ActiveNetParams)
+		if err != nil {
+			return err
+		}
+
+		addressString := scriptPublicKeyAddress.EncodeAddress()
+		if scriptPublicKeyType == txscript.NonStandardTy {
+			scriptPublicKeyHex := hex.EncodeToString(output.ScriptPublicKey.Script)
+			addressString = fmt.Sprintf("<Non-standard transaction script public key: %s>", scriptPublicKeyHex)
+		}
+
+		fmt.Printf("Output %d: \tRecipient: %s \tAmount: %.2f Kaspa\n",
+			index, addressString, float64(output.Value)/float64(constants.SompiPerKaspa))
+
+		allOutputSompi += output.Value
+	}
+	fmt.Println()
+
+	fmt.Printf("Fee:\t%d Sompi\n", allInputSompi-allOutputSompi)
+
+	return nil
+}

domain/consensus/consensus.go

@@ -286,13 +286,15 @@ func (s *consensus) GetBlockInfo(blockHash *externalapi.DomainHash) (*externalap
 
 	blockInfo.BlueScore = ghostdagData.BlueScore()
 	blockInfo.BlueWork = ghostdagData.BlueWork()
+	blockInfo.SelectedParent = ghostdagData.SelectedParent()
+	blockInfo.MergeSetBlues = ghostdagData.MergeSetBlues()
+	blockInfo.MergeSetReds = ghostdagData.MergeSetReds()
 
 	return blockInfo, nil
 }
 
 func (s *consensus) GetBlockRelations(blockHash *externalapi.DomainHash) (
-	parents []*externalapi.DomainHash, selectedParent *externalapi.DomainHash,
-	children []*externalapi.DomainHash, err error) {
+	parents []*externalapi.DomainHash, children []*externalapi.DomainHash, err error) {
 
 	s.lock.Lock()
 	defer s.lock.Unlock()
@@ -301,15 +303,10 @@ func (s *consensus) GetBlockRelations(blockHash *externalapi.DomainHash) (
 
 	blockRelation, err := s.blockRelationStores[0].BlockRelation(s.databaseContext, stagingArea, blockHash)
 	if err != nil {
-		return nil, nil, nil, err
+		return nil, nil, err
 	}
 
-	blockGHOSTDAGData, err := s.ghostdagDataStores[0].Get(s.databaseContext, stagingArea, blockHash, false)
-	if err != nil {
-		return nil, nil, nil, err
-	}
-
-	return blockRelation.Parents, blockGHOSTDAGData.SelectedParent(), blockRelation.Children, nil
+	return blockRelation.Parents, blockRelation.Children, nil
 }
 
 func (s *consensus) GetBlockAcceptanceData(blockHash *externalapi.DomainHash) (externalapi.AcceptanceData, error) {
@@ -346,6 +343,25 @@ func (s *consensus) GetHashesBetween(lowHash, highHash *externalapi.DomainHash,
 	return s.syncManager.GetHashesBetween(stagingArea, lowHash, highHash, maxBlocks)
 }
 
+func (s *consensus) GetAnticone(blockHash, contextHash *externalapi.DomainHash,
+	maxBlocks uint64) (hashes []*externalapi.DomainHash, err error) {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	stagingArea := model.NewStagingArea()
+
+	err = s.validateBlockHashExists(stagingArea, blockHash)
+	if err != nil {
+		return nil, err
+	}
+	err = s.validateBlockHashExists(stagingArea, contextHash)
+	if err != nil {
+		return nil, err
+	}
+
+	return s.syncManager.GetAnticone(stagingArea, blockHash, contextHash, maxBlocks)
+}
+
 func (s *consensus) GetMissingBlockBodyHashes(highHash *externalapi.DomainHash) ([]*externalapi.DomainHash, error) {
 	s.lock.Lock()
 	defer s.lock.Unlock()
@@ -704,7 +720,7 @@ func (s *consensus) Anticone(blockHash *externalapi.DomainHash) ([]*externalapi.
 		return nil, err
 	}
 
-	return s.dagTraversalManager.AnticoneFromBlocks(stagingArea, tips, blockHash)
+	return s.dagTraversalManager.AnticoneFromBlocks(stagingArea, tips, blockHash, 0)
 }
 
 func (s *consensus) EstimateNetworkHashesPerSecond(startHash *externalapi.DomainHash, windowSize int) (uint64, error) {
@@ -824,3 +840,16 @@ func (s *consensus) TrustedGHOSTDAGData(blockHash *externalapi.DomainHash) (*ext
 
 	return ghostdagData, nil
 }
+
+func (s *consensus) IsChainBlock(blockHash *externalapi.DomainHash) (bool, error) {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	stagingArea := model.NewStagingArea()
+	virtualGHOSTDAGData, err := s.ghostdagDataStores[0].Get(s.databaseContext, stagingArea, model.VirtualBlockHash, false)
+	if err != nil {
+		return false, err
+	}
+
+	return s.dagTopologyManagers[0].IsInSelectedParentChainOf(stagingArea, blockHash, virtualGHOSTDAGData.SelectedParent())
+}

domain/consensus/datastructures/blockwindowheapslicestore/block_window_heap_slice_staging_shard.go

@@ -0,0 +1,44 @@
+package blockwindowheapslicestore
+
+import (
+	"github.com/kaspanet/kaspad/domain/consensus/model"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+)
+
+type shardKey struct {
+	hash       externalapi.DomainHash
+	windowSize int
+}
+
+type blockWindowHeapSliceStagingShard struct {
+	store *blockWindowHeapSliceStore
+	toAdd map[shardKey][]*externalapi.BlockGHOSTDAGDataHashPair
+}
+
+func (bss *blockWindowHeapSliceStore) stagingShard(stagingArea *model.StagingArea) *blockWindowHeapSliceStagingShard {
+	return stagingArea.GetOrCreateShard(bss.shardID, func() model.StagingShard {
+		return &blockWindowHeapSliceStagingShard{
+			store: bss,
+			toAdd: make(map[shardKey][]*externalapi.BlockGHOSTDAGDataHashPair),
+		}
+	}).(*blockWindowHeapSliceStagingShard)
+}
+
+func (bsss *blockWindowHeapSliceStagingShard) Commit(_ model.DBTransaction) error {
+	for key, heapSlice := range bsss.toAdd {
+		bsss.store.cache.Add(&key.hash, key.windowSize, heapSlice)
+	}
+
+	return nil
+}
+
+func (bsss *blockWindowHeapSliceStagingShard) isStaged() bool {
+	return len(bsss.toAdd) != 0
+}
+
+func newShardKey(hash *externalapi.DomainHash, windowSize int) shardKey {
+	return shardKey{
+		hash:       *hash,
+		windowSize: windowSize,
+	}
+}

domain/consensus/datastructures/blockwindowheapslicestore/block_window_heap_slice_store.go

@@ -0,0 +1,47 @@
+package blockwindowheapslicestore
+
+import (
+	"github.com/kaspanet/kaspad/domain/consensus/model"
+	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/lrucachehashandwindowsizetoblockghostdagdatahashpairs"
+	"github.com/kaspanet/kaspad/infrastructure/db/database"
+	"github.com/kaspanet/kaspad/util/staging"
+	"github.com/pkg/errors"
+)
+
+type blockWindowHeapSliceStore struct {
+	shardID model.StagingShardID
+	cache   *lrucachehashandwindowsizetoblockghostdagdatahashpairs.LRUCache
+}
+
+// New instantiates a new WindowHeapSliceStore
+func New(cacheSize int, preallocate bool) model.WindowHeapSliceStore {
+	return &blockWindowHeapSliceStore{
+		shardID: staging.GenerateShardingID(),
+		cache:   lrucachehashandwindowsizetoblockghostdagdatahashpairs.New(cacheSize, preallocate),
+	}
+}
+
+// Stage stages the given blockStatus for the given blockHash
+func (bss *blockWindowHeapSliceStore) Stage(stagingArea *model.StagingArea, blockHash *externalapi.DomainHash, windowSize int, heapSlice []*externalapi.BlockGHOSTDAGDataHashPair) {
+	stagingShard := bss.stagingShard(stagingArea)
+	stagingShard.toAdd[newShardKey(blockHash, windowSize)] = heapSlice
+}
+
+func (bss *blockWindowHeapSliceStore) IsStaged(stagingArea *model.StagingArea) bool {
+	return bss.stagingShard(stagingArea).isStaged()
+}
+
+func (bss *blockWindowHeapSliceStore) Get(stagingArea *model.StagingArea, blockHash *externalapi.DomainHash, windowSize int) ([]*externalapi.BlockGHOSTDAGDataHashPair, error) {
+	stagingShard := bss.stagingShard(stagingArea)
+
+	if heapSlice, ok := stagingShard.toAdd[newShardKey(blockHash, windowSize)]; ok {
+		return heapSlice, nil
+	}
+
+	if heapSlice, ok := bss.cache.Get(blockHash, windowSize); ok {
+		return heapSlice, nil
+	}
+
+	return nil, errors.Wrap(database.ErrNotFound, "Window heap slice not found")
+}

domain/consensus/factory.go

@@ -1,12 +1,12 @@
 package consensus
 
 import (
+	"github.com/kaspanet/kaspad/domain/consensus/datastructures/blockwindowheapslicestore"
 	"github.com/kaspanet/kaspad/domain/consensus/datastructures/daawindowstore"
 	"github.com/kaspanet/kaspad/domain/consensus/model"
 	"github.com/kaspanet/kaspad/domain/consensus/processes/blockparentbuilder"
 	parentssanager "github.com/kaspanet/kaspad/domain/consensus/processes/parentsmanager"
 	"github.com/kaspanet/kaspad/domain/consensus/processes/pruningproofmanager"
-	"github.com/kaspanet/kaspad/domain/consensus/utils/constants"
 	"io/ioutil"
 	"os"
 	"sync"
@@ -145,9 +145,10 @@ func (f *factory) NewConsensus(config *Config, db infrastructuredatabase.Databas
 	finalityStore := finalitystore.New(prefixBucket, 200, preallocateCaches)
 	headersSelectedChainStore := headersselectedchainstore.New(prefixBucket, pruningWindowSizeForCaches, preallocateCaches)
 	daaBlocksStore := daablocksstore.New(prefixBucket, pruningWindowSizeForCaches, int(config.FinalityDepth()), preallocateCaches)
+	windowHeapSliceStore := blockwindowheapslicestore.New(2000, preallocateCaches)
 
 	blockRelationStores, reachabilityDataStores, ghostdagDataStores := dagStores(config, prefixBucket, pruningWindowSizePlusFinalityDepthForCache, pruningWindowSizeForCaches, preallocateCaches)
-	reachabilityManagers, dagTopologyManagers, ghostdagManagers, dagTraversalManagers := f.dagProcesses(config, dbManager, blockHeaderStore, daaWindowStore, blockRelationStores, reachabilityDataStores, ghostdagDataStores)
+	reachabilityManagers, dagTopologyManagers, ghostdagManagers, dagTraversalManagers := f.dagProcesses(config, dbManager, blockHeaderStore, daaWindowStore, windowHeapSliceStore, blockRelationStores, reachabilityDataStores, ghostdagDataStores)
 
 	blockRelationStore := blockRelationStores[0]
 	reachabilityDataStore := reachabilityDataStores[0]
@@ -158,7 +159,7 @@ func (f *factory) NewConsensus(config *Config, db infrastructuredatabase.Databas
 	dagTraversalManager := dagTraversalManagers[0]
 
 	// Processes
-	parentsManager := parentssanager.New(config.GenesisHash)
+	parentsManager := parentssanager.New(config.GenesisHash, config.MaxBlockLevel)
 	blockParentBuilder := blockparentbuilder.New(
 		dbManager,
 		blockHeaderStore,
@@ -168,6 +169,7 @@ func (f *factory) NewConsensus(config *Config, db infrastructuredatabase.Databas
 		pruningStore,
 
 		config.GenesisHash,
+		config.MaxBlockLevel,
 	)
 	pastMedianTimeManager := f.pastMedianTimeConsructor(
 		config.TimestampDeviationTolerance,
@@ -304,6 +306,7 @@ func (f *factory) NewConsensus(config *Config, db infrastructuredatabase.Databas
 		config.TimestampDeviationTolerance,
 		config.TargetTimePerBlock,
 		config.IgnoreHeaderMass,
+		config.MaxBlockLevel,
 
 		dbManager,
 		difficultyManager,
@@ -370,6 +373,7 @@ func (f *factory) NewConsensus(config *Config, db infrastructuredatabase.Databas
 	blockProcessor := blockprocessor.New(
 		genesisHash,
 		config.TargetTimePerBlock,
+		config.MaxBlockLevel,
 		dbManager,
 		consensusStateManager,
 		pruningManager,
@@ -417,6 +421,7 @@ func (f *factory) NewConsensus(config *Config, db infrastructuredatabase.Databas
 		genesisHash,
 		config.K,
 		config.PruningProofM,
+		config.MaxBlockLevel,
 	)
 
 	c := &consensus{
@@ -568,16 +573,16 @@ func dagStores(config *Config,
 	pruningWindowSizePlusFinalityDepthForCache, pruningWindowSizeForCaches int,
 	preallocateCaches bool) ([]model.BlockRelationStore, []model.ReachabilityDataStore, []model.GHOSTDAGDataStore) {
 
-	blockRelationStores := make([]model.BlockRelationStore, constants.MaxBlockLevel+1)
-	reachabilityDataStores := make([]model.ReachabilityDataStore, constants.MaxBlockLevel+1)
-	ghostdagDataStores := make([]model.GHOSTDAGDataStore, constants.MaxBlockLevel+1)
+	blockRelationStores := make([]model.BlockRelationStore, config.MaxBlockLevel+1)
+	reachabilityDataStores := make([]model.ReachabilityDataStore, config.MaxBlockLevel+1)
+	ghostdagDataStores := make([]model.GHOSTDAGDataStore, config.MaxBlockLevel+1)
 
 	ghostdagDataCacheSize := pruningWindowSizeForCaches * 2
 	if ghostdagDataCacheSize < config.DifficultyAdjustmentWindowSize {
 		ghostdagDataCacheSize = config.DifficultyAdjustmentWindowSize
 	}
 
-	for i := 0; i <= constants.MaxBlockLevel; i++ {
+	for i := 0; i <= config.MaxBlockLevel; i++ {
 		prefixBucket := prefixBucket.Bucket([]byte{byte(i)})
 		if i == 0 {
 			blockRelationStores[i] = blockrelationstore.New(prefixBucket, pruningWindowSizePlusFinalityDepthForCache, preallocateCaches)
@@ -597,6 +602,7 @@ func (f *factory) dagProcesses(config *Config,
 	dbManager model.DBManager,
 	blockHeaderStore model.BlockHeaderStore,
 	daaWindowStore model.BlocksWithTrustedDataDAAWindowStore,
+	windowHeapSliceStore model.WindowHeapSliceStore,
 	blockRelationStores []model.BlockRelationStore,
 	reachabilityDataStores []model.ReachabilityDataStore,
 	ghostdagDataStores []model.GHOSTDAGDataStore) (
@@ -606,12 +612,12 @@ func (f *factory) dagProcesses(config *Config,
 	[]model.DAGTraversalManager,
 ) {
 
-	reachabilityManagers := make([]model.ReachabilityManager, constants.MaxBlockLevel+1)
-	dagTopologyManagers := make([]model.DAGTopologyManager, constants.MaxBlockLevel+1)
-	ghostdagManagers := make([]model.GHOSTDAGManager, constants.MaxBlockLevel+1)
-	dagTraversalManagers := make([]model.DAGTraversalManager, constants.MaxBlockLevel+1)
+	reachabilityManagers := make([]model.ReachabilityManager, config.MaxBlockLevel+1)
+	dagTopologyManagers := make([]model.DAGTopologyManager, config.MaxBlockLevel+1)
+	ghostdagManagers := make([]model.GHOSTDAGManager, config.MaxBlockLevel+1)
+	dagTraversalManagers := make([]model.DAGTraversalManager, config.MaxBlockLevel+1)
 
-	for i := 0; i <= constants.MaxBlockLevel; i++ {
+	for i := 0; i <= config.MaxBlockLevel; i++ {
 		reachabilityManagers[i] = reachabilitymanager.New(
 			dbManager,
 			ghostdagDataStores[i],
@@ -638,6 +644,7 @@ func (f *factory) dagProcesses(config *Config,
 			reachabilityDataStores[i],
 			ghostdagManagers[i],
 			daaWindowStore,
+			windowHeapSliceStore,
 			config.GenesisHash,
 			config.DifficultyAdjustmentWindowSize)
 	}

domain/consensus/model/errors.go

@@ -5,3 +5,7 @@ import "github.com/pkg/errors"
 // ErrBlockNotInSelectedParentChain is returned from CreateHeadersSelectedChainBlockLocator if one of the parameters
 // passed to it are not in the headers selected parent chain
 var ErrBlockNotInSelectedParentChain = errors.New("Block is not in selected parent chain")
+
+// ErrReachedMaxTraversalAllowed is returned from AnticoneFromBlocks if `maxTraversalAllowed` was specified
+// and the traversal passed it
+var ErrReachedMaxTraversalAllowed = errors.New("Traversal searching for anticone passed the maxTraversalAllowed limit")

domain/consensus/model/externalapi/block.go

@@ -69,7 +69,7 @@ type BaseBlockHeader interface {
 	BlueScore() uint64
 	BlueWork() *big.Int
 	PruningPoint() *DomainHash
-	BlockLevel() int
+	BlockLevel(maxBlockLevel int) int
 	Equal(other BaseBlockHeader) bool
 }
 

domain/consensus/model/externalapi/blockinfo.go

@@ -4,18 +4,24 @@ import "math/big"
 
 // BlockInfo contains various information about a specific block
 type BlockInfo struct {
-	Exists      bool
-	BlockStatus BlockStatus
-	BlueScore   uint64
-	BlueWork    *big.Int
+	Exists         bool
+	BlockStatus    BlockStatus
+	BlueScore      uint64
+	BlueWork       *big.Int
+	SelectedParent *DomainHash
+	MergeSetBlues  []*DomainHash
+	MergeSetReds   []*DomainHash
 }
 
 // Clone returns a clone of BlockInfo
 func (bi *BlockInfo) Clone() *BlockInfo {
 	return &BlockInfo{
-		Exists:      bi.Exists,
-		BlockStatus: bi.BlockStatus.Clone(),
-		BlueScore:   bi.BlueScore,
-		BlueWork:    new(big.Int).Set(bi.BlueWork),
+		Exists:         bi.Exists,
+		BlockStatus:    bi.BlockStatus.Clone(),
+		BlueScore:      bi.BlueScore,
+		BlueWork:       new(big.Int).Set(bi.BlueWork),
+		SelectedParent: bi.SelectedParent,
+		MergeSetBlues:  CloneHashes(bi.MergeSetBlues),
+		MergeSetReds:   CloneHashes(bi.MergeSetReds),
 	}
 }

domain/consensus/model/externalapi/blockinfo_clone_test.go

@@ -14,31 +14,83 @@ func initTestBlockInfoStructsForClone() []*BlockInfo {
 			BlockStatus(0x01),
 			0,
 			big.NewInt(0),
+			nil,
+			[]*DomainHash{},
+			[]*DomainHash{},
 		}, {
 			true,
 			BlockStatus(0x02),
 			0,
 			big.NewInt(0),
+			nil,
+			[]*DomainHash{},
+			[]*DomainHash{},
 		}, {
 			true,
 			1,
 			1,
 			big.NewInt(0),
+			nil,
+			[]*DomainHash{},
+			[]*DomainHash{},
 		}, {
 			true,
 			255,
 			2,
 			big.NewInt(0),
+			nil,
+			[]*DomainHash{},
+			[]*DomainHash{},
 		}, {
 			true,
 			0,
 			3,
 			big.NewInt(0),
+			nil,
+			[]*DomainHash{},
+			[]*DomainHash{},
 		}, {
 			true,
 			BlockStatus(0x01),
 			0,
 			big.NewInt(1),
+			nil,
+			[]*DomainHash{},
+			[]*DomainHash{},
+		}, {
+			false,
+			BlockStatus(0x01),
+			0,
+			big.NewInt(1),
+			NewDomainHashFromByteArray(&[DomainHashSize]byte{
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01}),
+			[]*DomainHash{
+				NewDomainHashFromByteArray(&[DomainHashSize]byte{
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02}),
+				NewDomainHashFromByteArray(&[DomainHashSize]byte{
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03}),
+			},
+			[]*DomainHash{
+				NewDomainHashFromByteArray(&[DomainHashSize]byte{
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04}),
+				NewDomainHashFromByteArray(&[DomainHashSize]byte{
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x05}),
+			},
 		},
 	}
 	return tests

domain/consensus/model/externalapi/consensus.go

@@ -16,10 +16,11 @@ type Consensus interface {
 	GetBlockEvenIfHeaderOnly(blockHash *DomainHash) (*DomainBlock, error)
 	GetBlockHeader(blockHash *DomainHash) (BlockHeader, error)
 	GetBlockInfo(blockHash *DomainHash) (*BlockInfo, error)
-	GetBlockRelations(blockHash *DomainHash) (parents []*DomainHash, selectedParent *DomainHash, children []*DomainHash, err error)
+	GetBlockRelations(blockHash *DomainHash) (parents []*DomainHash, children []*DomainHash, err error)
 	GetBlockAcceptanceData(blockHash *DomainHash) (AcceptanceData, error)
 
 	GetHashesBetween(lowHash, highHash *DomainHash, maxBlocks uint64) (hashes []*DomainHash, actualHighHash *DomainHash, err error)
+	GetAnticone(blockHash, contextHash *DomainHash, maxBlocks uint64) (hashes []*DomainHash, err error)
 	GetMissingBlockBodyHashes(highHash *DomainHash) ([]*DomainHash, error)
 	GetPruningPointUTXOs(expectedPruningPointHash *DomainHash, fromOutpoint *DomainOutpoint, limit int) ([]*OutpointAndUTXOEntryPair, error)
 	GetVirtualUTXOs(expectedVirtualParents []*DomainHash, fromOutpoint *DomainOutpoint, limit int) ([]*OutpointAndUTXOEntryPair, error)
@@ -50,4 +51,5 @@ type Consensus interface {
 	TrustedDataDataDAAHeader(trustedBlockHash, daaBlockHash *DomainHash, daaBlockWindowIndex uint64) (*TrustedDataDataDAAHeader, error)
 	TrustedBlockAssociatedGHOSTDAGDataBlockHashes(blockHash *DomainHash) ([]*DomainHash, error)
 	TrustedGHOSTDAGData(blockHash *DomainHash) (*BlockGHOSTDAGData, error)
+	IsChainBlock(blockHash *DomainHash) (bool, error)
 }

domain/consensus/model/interface_datastructures_windowheapstore.go

@@ -0,0 +1,11 @@
+package model
+
+import "github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+
+// WindowHeapSliceStore caches the slices that are needed for the heap implementation of DAGTraversalManager.BlockWindow
+type WindowHeapSliceStore interface {
+	Store
+	Stage(stagingArea *StagingArea, blockHash *externalapi.DomainHash, windowSize int, pairs []*externalapi.BlockGHOSTDAGDataHashPair)
+	IsStaged(stagingArea *StagingArea) bool
+	Get(stagingArea *StagingArea, blockHash *externalapi.DomainHash, windowSize int) ([]*externalapi.BlockGHOSTDAGDataHashPair, error)
+}

domain/consensus/model/interface_processes_dagtraversalmanager.go

@@ -10,7 +10,7 @@ type DAGTraversalManager interface {
 	// from lowHash (exclusive) to highHash (inclusive) over highHash's selected parent chain
 	SelectedChildIterator(stagingArea *StagingArea, highHash, lowHash *externalapi.DomainHash, includeLowHash bool) (BlockIterator, error)
 	SelectedChild(stagingArea *StagingArea, highHash, lowHash *externalapi.DomainHash) (*externalapi.DomainHash, error)
-	AnticoneFromBlocks(stagingArea *StagingArea, tips []*externalapi.DomainHash, blockHash *externalapi.DomainHash) ([]*externalapi.DomainHash, error)
+	AnticoneFromBlocks(stagingArea *StagingArea, tips []*externalapi.DomainHash, blockHash *externalapi.DomainHash, maxTraversalAllowed uint64) ([]*externalapi.DomainHash, error)
 	AnticoneFromVirtualPOV(stagingArea *StagingArea, blockHash *externalapi.DomainHash) ([]*externalapi.DomainHash, error)
 	BlockWindow(stagingArea *StagingArea, highHash *externalapi.DomainHash, windowSize int) ([]*externalapi.DomainHash, error)
 	DAABlockWindow(stagingArea *StagingArea, highHash *externalapi.DomainHash) ([]*externalapi.DomainHash, error)

domain/consensus/model/interface_processes_syncmanager.go

@@ -6,6 +6,7 @@ import "github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
 type SyncManager interface {
 	GetHashesBetween(stagingArea *StagingArea, lowHash, highHash *externalapi.DomainHash, maxBlocks uint64) (
 		hashes []*externalapi.DomainHash, actualHighHash *externalapi.DomainHash, err error)
+	GetAnticone(stagingArea *StagingArea, blockHash, contextHash *externalapi.DomainHash, maxBlocks uint64) (hashes []*externalapi.DomainHash, err error)
 	GetMissingBlockBodyHashes(stagingArea *StagingArea, highHash *externalapi.DomainHash) ([]*externalapi.DomainHash, error)
 	CreateBlockLocator(stagingArea *StagingArea, lowHash, highHash *externalapi.DomainHash, limit uint32) (
 		externalapi.BlockLocator, error)

domain/consensus/model/testapi/test_consensus.go

@@ -49,6 +49,7 @@ type TestConsensus interface {
 		*externalapi.VirtualChangeSet, error)
 
 	MineJSON(r io.Reader, blockType MineJSONBlockType) (tips []*externalapi.DomainHash, err error)
+	ToJSON(w io.Writer) error
 
 	RenderDAGToDot(filename string) error
 

domain/consensus/processes/blockparentbuilder/blockparentbuilder.go

@@ -16,7 +16,8 @@ type blockParentBuilder struct {
 	reachabilityDataStore model.ReachabilityDataStore
 	pruningStore          model.PruningStore
 
-	genesisHash *externalapi.DomainHash
+	genesisHash   *externalapi.DomainHash
+	maxBlockLevel int
 }
 
 // New creates a new instance of a BlockParentBuilder
@@ -30,6 +31,7 @@ func New(
 	pruningStore model.PruningStore,
 
 	genesisHash *externalapi.DomainHash,
+	maxBlockLevel int,
 ) model.BlockParentBuilder {
 	return &blockParentBuilder{
 		databaseContext:    databaseContext,
@@ -40,6 +42,7 @@ func New(
 		reachabilityDataStore: reachabilityDataStore,
 		pruningStore:          pruningStore,
 		genesisHash:           genesisHash,
+		maxBlockLevel:         maxBlockLevel,
 	}
 }
 
@@ -102,7 +105,7 @@ func (bpb *blockParentBuilder) BuildParents(stagingArea *model.StagingArea,
 	// all the block levels they occupy
 	for _, directParentHeader := range directParentHeaders {
 		directParentHash := consensushashing.HeaderHash(directParentHeader)
-		blockLevel := directParentHeader.BlockLevel()
+		blockLevel := directParentHeader.BlockLevel(bpb.maxBlockLevel)
 		for i := 0; i <= blockLevel; i++ {
 			if _, exists := candidatesByLevelToReferenceBlocksMap[i]; !exists {
 				candidatesByLevelToReferenceBlocksMap[i] = make(map[externalapi.DomainHash][]*externalapi.DomainHash)

domain/consensus/processes/blockprocessor/blockprocessor.go

@@ -14,6 +14,7 @@ import (
 type blockProcessor struct {
 	genesisHash        *externalapi.DomainHash
 	targetTimePerBlock time.Duration
+	maxBlockLevel      int
 	databaseContext    model.DBManager
 	blockLogger        *blocklogger.BlockLogger
 
@@ -52,6 +53,7 @@ type blockProcessor struct {
 func New(
 	genesisHash *externalapi.DomainHash,
 	targetTimePerBlock time.Duration,
+	maxBlockLevel int,
 	databaseContext model.DBManager,
 
 	consensusStateManager model.ConsensusStateManager,
@@ -86,6 +88,7 @@ func New(
 	return &blockProcessor{
 		genesisHash:           genesisHash,
 		targetTimePerBlock:    targetTimePerBlock,
+		maxBlockLevel:         maxBlockLevel,
 		databaseContext:       databaseContext,
 		blockLogger:           blocklogger.NewBlockLogger(),
 		pruningManager:        pruningManager,

domain/consensus/processes/blockprocessor/validate_and_insert_block.go

@@ -259,7 +259,7 @@ func (bp *blockProcessor) updateReachabilityReindexRoot(stagingArea *model.Stagi
 		return err
 	}
 
-	headersSelectedTipHeaderBlockLevel := headersSelectedTipHeader.BlockLevel()
+	headersSelectedTipHeaderBlockLevel := headersSelectedTipHeader.BlockLevel(bp.maxBlockLevel)
 	for blockLevel := 0; blockLevel <= headersSelectedTipHeaderBlockLevel; blockLevel++ {
 		err := bp.reachabilityManagers[blockLevel].UpdateReindexRoot(stagingArea, headersSelectedTip)
 		if err != nil {

domain/consensus/processes/blockvalidator/block_header_in_context.go

@@ -62,7 +62,7 @@ func (v *blockValidator) ValidateHeaderInContext(stagingArea *model.StagingArea,
 		return err
 	}
 	if !hasReachabilityData {
-		blockLevel := header.BlockLevel()
+		blockLevel := header.BlockLevel(v.maxBlockLevel)
 		for i := 0; i <= blockLevel; i++ {
 			err = v.reachabilityManagers[i].AddBlock(stagingArea, blockHash)
 			if err != nil {

domain/consensus/processes/blockvalidator/blockvalidator.go

@@ -23,6 +23,7 @@ type blockValidator struct {
 	timestampDeviationTolerance int
 	targetTimePerBlock          time.Duration
 	ignoreHeaderMass            bool
+	maxBlockLevel               int
 
 	databaseContext       model.DBReader
 	difficultyManager     model.DifficultyManager
@@ -60,6 +61,7 @@ func New(powMax *big.Int,
 	timestampDeviationTolerance int,
 	targetTimePerBlock time.Duration,
 	ignoreHeaderMass bool,
+	maxBlockLevel int,
 
 	databaseContext model.DBReader,
 
@@ -97,6 +99,7 @@ func New(powMax *big.Int,
 		mergeSetSizeLimit:          mergeSetSizeLimit,
 		maxBlockParents:            maxBlockParents,
 		ignoreHeaderMass:           ignoreHeaderMass,
+		maxBlockLevel:              maxBlockLevel,
 
 		timestampDeviationTolerance: timestampDeviationTolerance,
 		targetTimePerBlock:          targetTimePerBlock,

domain/consensus/processes/blockvalidator/pruning_violation_proof_of_work_and_difficulty.go

@@ -69,7 +69,7 @@ func (v *blockValidator) setParents(stagingArea *model.StagingArea,
 	header externalapi.BlockHeader,
 	isBlockWithTrustedData bool) error {
 
-	for level := 0; level <= header.BlockLevel(); level++ {
+	for level := 0; level <= header.BlockLevel(v.maxBlockLevel); level++ {
 		var parents []*externalapi.DomainHash
 		for _, parent := range v.parentsManager.ParentsAtLevel(header, level) {
 			_, err := v.ghostdagDataStores[level].Get(v.databaseContext, stagingArea, parent, false)
@@ -118,7 +118,7 @@ func (v *blockValidator) validateDifficulty(stagingArea *model.StagingArea,
 		return err
 	}
 
-	blockLevel := header.BlockLevel()
+	blockLevel := header.BlockLevel(v.maxBlockLevel)
 	for i := 1; i <= blockLevel; i++ {
 		err = v.ghostdagManagers[i].GHOSTDAG(stagingArea, blockHash)
 		if err != nil {

domain/consensus/processes/consensusstatemanager/pick_virtual_parents.go

@@ -336,12 +336,12 @@ func (csm *consensusStateManager) boundedMergeBreakingParents(stagingArea *model
 		log.Debugf("Checking whether parent %s breaks the bounded merge set", parent)
 		isBadRedInPast := false
 		for _, badRedBlock := range badReds {
-			isBadRedInPast, err = csm.dagTopologyManager.IsAncestorOf(stagingArea, parent, badRedBlock)
+			isBadRedInPast, err = csm.dagTopologyManager.IsAncestorOf(stagingArea, badRedBlock, parent)
 			if err != nil {
 				return nil, err
 			}
 			if isBadRedInPast {
-				log.Debugf("Parent %s is an ancestor of bad red %s", parent, badRedBlock)
+				log.Debugf("Parent %s is a descendant of bad red %s", parent, badRedBlock)
 				break
 			}
 		}

domain/consensus/processes/dagtraversalmanager/anticone.go

@@ -4,6 +4,7 @@ import (
 	"github.com/kaspanet/kaspad/domain/consensus/model"
 	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
 	"github.com/kaspanet/kaspad/domain/consensus/utils/hashset"
+	"github.com/pkg/errors"
 )
 
 func (dtm *dagTraversalManager) AnticoneFromVirtualPOV(stagingArea *model.StagingArea, blockHash *externalapi.DomainHash) (
@@ -14,16 +15,18 @@ func (dtm *dagTraversalManager) AnticoneFromVirtualPOV(stagingArea *model.Stagin
 		return nil, err
 	}
 
-	return dtm.AnticoneFromBlocks(stagingArea, virtualParents, blockHash)
+	return dtm.AnticoneFromBlocks(stagingArea, virtualParents, blockHash, 0)
 }
 
-func (dtm *dagTraversalManager) AnticoneFromBlocks(stagingArea *model.StagingArea, tips []*externalapi.DomainHash, blockHash *externalapi.DomainHash) (
+func (dtm *dagTraversalManager) AnticoneFromBlocks(stagingArea *model.StagingArea, tips []*externalapi.DomainHash,
+	blockHash *externalapi.DomainHash, maxTraversalAllowed uint64) (
 	[]*externalapi.DomainHash, error) {
 
 	anticone := []*externalapi.DomainHash{}
 	queue := tips
 	visited := hashset.New()
 
+	traversalCounter := uint64(0)
 	for len(queue) > 0 {
 		var current *externalapi.DomainHash
 		current, queue = queue[0], queue[1:]
@@ -48,6 +51,14 @@ func (dtm *dagTraversalManager) AnticoneFromBlocks(stagingArea *model.StagingAre
 			return nil, err
 		}
 
+		// We count the number of blocks in past(tips) \setminus past(blockHash).
+		// We don't use `len(visited)` since it includes some maximal blocks in past(blockHash) as well.
+		traversalCounter++
+		if maxTraversalAllowed > 0 && traversalCounter > maxTraversalAllowed {
+			return nil, errors.Wrapf(model.ErrReachedMaxTraversalAllowed,
+				"Passed max allowed traversal (%d > %d)", traversalCounter, maxTraversalAllowed)
+		}
+
 		if !blockIsAncestorOfCurrent {
 			anticone = append(anticone, current)
 		}

domain/consensus/processes/dagtraversalmanager/block_heap.go

@@ -152,6 +152,18 @@ func (dtm *dagTraversalManager) newSizedUpHeap(stagingArea *model.StagingArea, c
 	return &h
 }
 
+func (dtm *dagTraversalManager) newSizedUpHeapFromSlice(stagingArea *model.StagingArea, slice []*externalapi.BlockGHOSTDAGDataHashPair) *sizedUpBlockHeap {
+	sliceClone := make([]*externalapi.BlockGHOSTDAGDataHashPair, len(slice), cap(slice))
+	copy(sliceClone, slice)
+	h := sizedUpBlockHeap{
+		impl:          upHeap{baseHeap{slice: sliceClone, ghostdagManager: dtm.ghostdagManager}},
+		ghostdagStore: dtm.ghostdagDataStore,
+		dbContext:     dtm.databaseContext,
+		stagingArea:   stagingArea,
+	}
+	return &h
+}
+
 // len returns the length of this heap
 func (sbh *sizedUpBlockHeap) len() int {
 	return sbh.impl.Len()

domain/consensus/processes/dagtraversalmanager/dagtraversalmanager.go

@@ -18,6 +18,7 @@ type dagTraversalManager struct {
 	daaWindowStore                 model.BlocksWithTrustedDataDAAWindowStore
 	genesisHash                    *externalapi.DomainHash
 	difficultyAdjustmentWindowSize int
+	windowHeapSliceStore           model.WindowHeapSliceStore
 }
 
 // New instantiates a new DAGTraversalManager
@@ -28,6 +29,7 @@ func New(
 	reachabilityDataStore model.ReachabilityDataStore,
 	ghostdagManager model.GHOSTDAGManager,
 	daaWindowStore model.BlocksWithTrustedDataDAAWindowStore,
+	windowHeapSliceStore model.WindowHeapSliceStore,
 	genesisHash *externalapi.DomainHash,
 	difficultyAdjustmentWindowSize int) model.DAGTraversalManager {
 	return &dagTraversalManager{
@@ -40,6 +42,7 @@ func New(
 
 		genesisHash:                    genesisHash,
 		difficultyAdjustmentWindowSize: difficultyAdjustmentWindowSize,
+		windowHeapSliceStore:           windowHeapSliceStore,
 	}
 }
 

domain/consensus/processes/dagtraversalmanager/window.go

@@ -16,7 +16,7 @@ func (dtm *dagTraversalManager) DAABlockWindow(stagingArea *model.StagingArea, h
 func (dtm *dagTraversalManager) BlockWindow(stagingArea *model.StagingArea, highHash *externalapi.DomainHash,
 	windowSize int) ([]*externalapi.DomainHash, error) {
 
-	windowHeap, err := dtm.calculateBlockWindowHeap(stagingArea, highHash, windowSize)
+	windowHeap, err := dtm.blockWindowHeap(stagingArea, highHash, windowSize)
 	if err != nil {
 		return nil, err
 	}
@@ -28,6 +28,28 @@ func (dtm *dagTraversalManager) BlockWindow(stagingArea *model.StagingArea, high
 	return window, nil
 }
 
+func (dtm *dagTraversalManager) blockWindowHeap(stagingArea *model.StagingArea,
+	highHash *externalapi.DomainHash, windowSize int) (*sizedUpBlockHeap, error) {
+	windowHeapSlice, err := dtm.windowHeapSliceStore.Get(stagingArea, highHash, windowSize)
+	sliceNotCached := database.IsNotFoundError(err)
+	if !sliceNotCached && err != nil {
+		return nil, err
+	}
+	if !sliceNotCached {
+		return dtm.newSizedUpHeapFromSlice(stagingArea, windowHeapSlice), nil
+	}
+
+	heap, err := dtm.calculateBlockWindowHeap(stagingArea, highHash, windowSize)
+	if err != nil {
+		return nil, err
+	}
+
+	if !highHash.Equal(model.VirtualBlockHash) {
+		dtm.windowHeapSliceStore.Stage(stagingArea, highHash, windowSize, heap.impl.slice)
+	}
+	return heap, nil
+}
+
 func (dtm *dagTraversalManager) calculateBlockWindowHeap(stagingArea *model.StagingArea,
 	highHash *externalapi.DomainHash, windowSize int) (*sizedUpBlockHeap, error) {
 
@@ -45,18 +67,54 @@ func (dtm *dagTraversalManager) calculateBlockWindowHeap(stagingArea *model.Stag
 		return nil, err
 	}
 
+	// If the block has a trusted DAA window attached, we just take it as is and don't use cache of selected parent to
+	// build the window. This is because tryPushMergeSet might not be able to find all the GHOSTDAG data that is
+	// associated with the block merge set.
+	_, err = dtm.daaWindowStore.DAAWindowBlock(dtm.databaseContext, stagingArea, current, 0)
+	isNonTrustedBlock := database.IsNotFoundError(err)
+	if !isNonTrustedBlock && err != nil {
+		return nil, err
+	}
+
+	if isNonTrustedBlock && currentGHOSTDAGData.SelectedParent() != nil {
+		windowHeapSlice, err := dtm.windowHeapSliceStore.Get(stagingArea, currentGHOSTDAGData.SelectedParent(), windowSize)
+		selectedParentNotCached := database.IsNotFoundError(err)
+		if !selectedParentNotCached && err != nil {
+			return nil, err
+		}
+		if !selectedParentNotCached {
+			windowHeap := dtm.newSizedUpHeapFromSlice(stagingArea, windowHeapSlice)
+			if !currentGHOSTDAGData.SelectedParent().Equal(dtm.genesisHash) {
+				selectedParentGHOSTDAGData, err := dtm.ghostdagDataStore.Get(
+					dtm.databaseContext, stagingArea, currentGHOSTDAGData.SelectedParent(), false)
+				if err != nil {
+					return nil, err
+				}
+
+				_, err = dtm.tryPushMergeSet(windowHeap, currentGHOSTDAGData, selectedParentGHOSTDAGData)
+				if err != nil {
+					return nil, err
+				}
+			}
+
+			return windowHeap, nil
+		}
+	}
+
+	// Walk down the chain until you finish or find a trusted block and then take complete the rest
+	// of the window with the trusted window.
 	for {
 		if currentGHOSTDAGData.SelectedParent().Equal(dtm.genesisHash) {
 			break
 		}
 
 		_, err := dtm.daaWindowStore.DAAWindowBlock(dtm.databaseContext, stagingArea, current, 0)
-		isNotFoundError := database.IsNotFoundError(err)
-		if !isNotFoundError && err != nil {
+		currentIsNonTrustedBlock := database.IsNotFoundError(err)
+		if !currentIsNonTrustedBlock && err != nil {
 			return nil, err
 		}
 
-		if !isNotFoundError {
+		if !currentIsNonTrustedBlock {
 			for i := uint64(0); ; i++ {
 				daaBlock, err := dtm.daaWindowStore.DAAWindowBlock(dtm.databaseContext, stagingArea, current, i)
 				if database.IsNotFoundError(err) {
@@ -83,47 +141,60 @@ func (dtm *dagTraversalManager) calculateBlockWindowHeap(stagingArea *model.Stag
 		if err != nil {
 			return nil, err
 		}
-		added, err := windowHeap.tryPushWithGHOSTDAGData(currentGHOSTDAGData.SelectedParent(), selectedParentGHOSTDAGData)
+
+		done, err := dtm.tryPushMergeSet(windowHeap, currentGHOSTDAGData, selectedParentGHOSTDAGData)
 		if err != nil {
 			return nil, err
 		}
-
-		// If the window is full and the selected parent is less than the minimum then we break
-		// because this means that there cannot be any more blocks in the past with higher blueWork
-		if !added {
+		if done {
 			break
 		}
 
-		// Now we go over the merge set.
-		// Remove the SP from the blue merge set because we already added it.
-		mergeSetBlues := currentGHOSTDAGData.MergeSetBlues()[1:]
-		// Go over the merge set in reverse because it's ordered in reverse by blueWork.
-		for i := len(mergeSetBlues) - 1; i >= 0; i-- {
-			added, err := windowHeap.tryPush(mergeSetBlues[i])
-			if err != nil {
-				return nil, err
-			}
-			// If it's smaller than minimum then we won't be able to add the rest because they're even smaller.
-			if !added {
-				break
-			}
-		}
-
-		mergeSetReds := currentGHOSTDAGData.MergeSetReds()
-		for i := len(mergeSetReds) - 1; i >= 0; i-- {
-			added, err := windowHeap.tryPush(mergeSetReds[i])
-			if err != nil {
-				return nil, err
-			}
-			// If it's smaller than minimum then we won't be able to add the rest because they're even smaller.
-			if !added {
-				break
-			}
-		}
-
 		current = currentGHOSTDAGData.SelectedParent()
 		currentGHOSTDAGData = selectedParentGHOSTDAGData
 	}
 
 	return windowHeap, nil
 }
+
+func (dtm *dagTraversalManager) tryPushMergeSet(windowHeap *sizedUpBlockHeap, currentGHOSTDAGData, selectedParentGHOSTDAGData *externalapi.BlockGHOSTDAGData) (bool, error) {
+	added, err := windowHeap.tryPushWithGHOSTDAGData(currentGHOSTDAGData.SelectedParent(), selectedParentGHOSTDAGData)
+	if err != nil {
+		return false, err
+	}
+
+	// If the window is full and the selected parent is less than the minimum then we break
+	// because this means that there cannot be any more blocks in the past with higher blueWork
+	if !added {
+		return true, nil
+	}
+
+	// Now we go over the merge set.
+	// Remove the SP from the blue merge set because we already added it.
+	mergeSetBlues := currentGHOSTDAGData.MergeSetBlues()[1:]
+	// Go over the merge set in reverse because it's ordered in reverse by blueWork.
+	for i := len(mergeSetBlues) - 1; i >= 0; i-- {
+		added, err := windowHeap.tryPush(mergeSetBlues[i])
+		if err != nil {
+			return false, err
+		}
+		// If it's smaller than minimum then we won't be able to add the rest because they're even smaller.
+		if !added {
+			break
+		}
+	}
+
+	mergeSetReds := currentGHOSTDAGData.MergeSetReds()
+	for i := len(mergeSetReds) - 1; i >= 0; i-- {
+		added, err := windowHeap.tryPush(mergeSetReds[i])
+		if err != nil {
+			return false, err
+		}
+		// If it's smaller than minimum then we won't be able to add the rest because they're even smaller.
+		if !added {
+			break
+		}
+	}
+
+	return false, nil
+}

domain/consensus/processes/parentsmanager/parentsmanager.go

@@ -3,17 +3,18 @@ package parentssanager
 import (
 	"github.com/kaspanet/kaspad/domain/consensus/model"
 	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
-	"github.com/kaspanet/kaspad/domain/consensus/utils/constants"
 )
 
 type parentsManager struct {
-	genesisHash *externalapi.DomainHash
+	genesisHash   *externalapi.DomainHash
+	maxBlockLevel int
 }
 
 // New instantiates a new ParentsManager
-func New(genesisHash *externalapi.DomainHash) model.ParentsManager {
+func New(genesisHash *externalapi.DomainHash, maxBlockLevel int) model.ParentsManager {
 	return &parentsManager{
-		genesisHash: genesisHash,
+		genesisHash:   genesisHash,
+		maxBlockLevel: maxBlockLevel,
 	}
 }
 
@@ -31,7 +32,7 @@ func (pm *parentsManager) ParentsAtLevel(blockHeader externalapi.BlockHeader, le
 }
 
 func (pm *parentsManager) Parents(blockHeader externalapi.BlockHeader) []externalapi.BlockLevelParents {
-	numParents := constants.MaxBlockLevel + 1
+	numParents := pm.maxBlockLevel + 1
 	parents := make([]externalapi.BlockLevelParents, numParents)
 	for i := 0; i < numParents; i++ {
 		parents[i] = pm.ParentsAtLevel(blockHeader, i)

domain/consensus/processes/pruningmanager/pruning_test.go

@@ -38,8 +38,8 @@ func TestPruning(t *testing.T) {
 		"dag-for-test-pruning.json": {
 			dagconfig.MainnetParams.Name: "503",
 			dagconfig.TestnetParams.Name: "502",
-			dagconfig.DevnetParams.Name:  "503",
-			dagconfig.SimnetParams.Name:  "502",
+			dagconfig.DevnetParams.Name:  "502",
+			dagconfig.SimnetParams.Name:  "503",
 		},
 	}
 

domain/consensus/processes/pruningmanager/pruningmanager.go

@@ -995,7 +995,13 @@ func (pm *pruningManager) ExpectedHeaderPruningPoint(stagingArea *model.StagingA
 		return nil, err
 	}
 
-	if hasPruningPointInItsSelectedChain && pm.finalityScore(ghostdagData.BlueScore()) > pm.finalityScore(selectedParentPruningPointHeader.BlueScore()+pm.pruningDepth) {
+	// Note: the pruning point from the POV of the current block is the first block in its chain that is in depth of pm.pruningDepth and
+	// its finality score is greater than the previous pruning point. This is why the diff between finalityScore(selectedParent.blueScore + 1) * finalityInterval
+	// and the current block blue score is less than pm.pruningDepth we can know for sure that this block didn't trigger a pruning point change.
+	minRequiredBlueScoreForNextPruningPoint := (pm.finalityScore(selectedParentPruningPointHeader.BlueScore()) + 1) * pm.finalityInterval
+
+	if hasPruningPointInItsSelectedChain &&
+		minRequiredBlueScoreForNextPruningPoint+pm.pruningDepth <= ghostdagData.BlueScore() {
 		var suggestedLowHash *externalapi.DomainHash
 		hasReachabilityData, err := pm.reachabilityDataStore.HasReachabilityData(pm.databaseContext, stagingArea, selectedParentHeader.PruningPoint())
 		if err != nil {
@@ -1003,7 +1009,15 @@ func (pm *pruningManager) ExpectedHeaderPruningPoint(stagingArea *model.StagingA
 		}
 
 		if hasReachabilityData {
-			suggestedLowHash = selectedParentHeader.PruningPoint()
+			// nextPruningPointAndCandidateByBlockHash needs suggestedLowHash to be in the future of the pruning point because
+			// otherwise reachability selected chain data is unreliable.
+			isInFutureOfCurrentPruningPoint, err := pm.dagTopologyManager.IsAncestorOf(stagingArea, pruningPoint, selectedParentHeader.PruningPoint())
+			if err != nil {
+				return nil, err
+			}
+			if isInFutureOfCurrentPruningPoint {
+				suggestedLowHash = selectedParentHeader.PruningPoint()
+			}
 		}
 
 		nextOrCurrentPruningPoint, _, err = pm.nextPruningPointAndCandidateByBlockHash(stagingArea, blockHash, suggestedLowHash)

domain/consensus/processes/pruningproofmanager/pruningproofmanager.go

@@ -13,7 +13,6 @@ import (
 	"github.com/kaspanet/kaspad/domain/consensus/processes/reachabilitymanager"
 	"github.com/kaspanet/kaspad/domain/consensus/ruleerrors"
 	"github.com/kaspanet/kaspad/domain/consensus/utils/consensushashing"
-	"github.com/kaspanet/kaspad/domain/consensus/utils/constants"
 	"github.com/kaspanet/kaspad/domain/consensus/utils/hashset"
 	"github.com/kaspanet/kaspad/infrastructure/db/database"
 	"github.com/kaspanet/kaspad/infrastructure/logger"
@@ -41,6 +40,7 @@ type pruningProofManager struct {
 	genesisHash   *externalapi.DomainHash
 	k             externalapi.KType
 	pruningProofM uint64
+	maxBlockLevel int
 
 	cachedPruningPoint *externalapi.DomainHash
 	cachedProof        *externalapi.PruningPointProof
@@ -66,6 +66,7 @@ func New(
 	genesisHash *externalapi.DomainHash,
 	k externalapi.KType,
 	pruningProofM uint64,
+	maxBlockLevel int,
 ) model.PruningProofManager {
 
 	return &pruningProofManager{
@@ -86,6 +87,7 @@ func New(
 		genesisHash:   genesisHash,
 		k:             k,
 		pruningProofM: pruningProofM,
+		maxBlockLevel: maxBlockLevel,
 	}
 }
 
@@ -134,7 +136,7 @@ func (ppm *pruningProofManager) buildPruningPointProof(stagingArea *model.Stagin
 	maxLevel := len(ppm.parentsManager.Parents(pruningPointHeader)) - 1
 	headersByLevel := make(map[int][]externalapi.BlockHeader)
 	selectedTipByLevel := make([]*externalapi.DomainHash, maxLevel+1)
-	pruningPointLevel := pruningPointHeader.BlockLevel()
+	pruningPointLevel := pruningPointHeader.BlockLevel(ppm.maxBlockLevel)
 	for blockLevel := maxLevel; blockLevel >= 0; blockLevel-- {
 		var selectedTip *externalapi.DomainHash
 		if blockLevel <= pruningPointLevel {
@@ -310,7 +312,7 @@ func (ppm *pruningProofManager) ValidatePruningPointProof(pruningPointProof *ext
 	level0Headers := pruningPointProof.Headers[0]
 	pruningPointHeader := level0Headers[len(level0Headers)-1]
 	pruningPoint := consensushashing.HeaderHash(pruningPointHeader)
-	pruningPointBlockLevel := pruningPointHeader.BlockLevel()
+	pruningPointBlockLevel := pruningPointHeader.BlockLevel(ppm.maxBlockLevel)
 	maxLevel := len(ppm.parentsManager.Parents(pruningPointHeader)) - 1
 	if maxLevel >= len(pruningPointProof.Headers) {
 		return errors.Wrapf(ruleerrors.ErrPruningProofEmpty, "proof has only %d levels while pruning point "+
@@ -354,9 +356,9 @@ func (ppm *pruningProofManager) ValidatePruningPointProof(pruningPointProof *ext
 		var selectedTip *externalapi.DomainHash
 		for i, header := range headers {
 			blockHash := consensushashing.HeaderHash(header)
-			if header.BlockLevel() < blockLevel {
+			if header.BlockLevel(ppm.maxBlockLevel) < blockLevel {
 				return errors.Wrapf(ruleerrors.ErrPruningProofWrongBlockLevel, "block %s level is %d when it's "+
-					"expected to be at least %d", blockHash, header.BlockLevel(), blockLevel)
+					"expected to be at least %d", blockHash, header.BlockLevel(ppm.maxBlockLevel), blockLevel)
 			}
 
 			blockHeaderStore.Stage(stagingArea, blockHash, header)
@@ -581,9 +583,9 @@ func (ppm *pruningProofManager) dagProcesses(
 	[]model.GHOSTDAGManager,
 ) {
 
-	reachabilityManagers := make([]model.ReachabilityManager, constants.MaxBlockLevel+1)
-	dagTopologyManagers := make([]model.DAGTopologyManager, constants.MaxBlockLevel+1)
-	ghostdagManagers := make([]model.GHOSTDAGManager, constants.MaxBlockLevel+1)
+	reachabilityManagers := make([]model.ReachabilityManager, ppm.maxBlockLevel+1)
+	dagTopologyManagers := make([]model.DAGTopologyManager, ppm.maxBlockLevel+1)
+	ghostdagManagers := make([]model.GHOSTDAGManager, ppm.maxBlockLevel+1)
 
 	for i := 0; i <= maxLevel; i++ {
 		reachabilityManagers[i] = reachabilitymanager.New(
@@ -627,9 +629,9 @@ func (ppm *pruningProofManager) ApplyPruningPointProof(pruningPointProof *extern
 			stagingArea := model.NewStagingArea()
 
 			blockHash := consensushashing.HeaderHash(header)
-			if header.BlockLevel() < blockLevel {
+			if header.BlockLevel(ppm.maxBlockLevel) < blockLevel {
 				return errors.Wrapf(ruleerrors.ErrPruningProofWrongBlockLevel, "block %s level is %d when it's "+
-					"expected to be at least %d", blockHash, header.BlockLevel(), blockLevel)
+					"expected to be at least %d", blockHash, header.BlockLevel(ppm.maxBlockLevel), blockLevel)
 			}
 
 			ppm.blockHeaderStore.Stage(stagingArea, blockHash, header)

domain/consensus/processes/syncmanager/antipast.go

@@ -145,7 +145,7 @@ func (sm *syncManager) missingBlockBodyHashes(stagingArea *model.StagingArea, hi
 		lowHash = selectedChild
 	}
 	if !foundHeaderOnlyBlock {
-		if lowHash == highHash {
+		if lowHash.Equal(highHash) {
 			// Blocks can be inserted inside the DAG during IBD if those were requested before IBD started.
 			// In rare cases, all the IBD blocks might be already inserted by the time we reach this point.
 			// In these cases - return an empty list of blocks to sync
@@ -153,7 +153,7 @@ func (sm *syncManager) missingBlockBodyHashes(stagingArea *model.StagingArea, hi
 		}
 		// TODO: Once block children are fixed (https://github.com/kaspanet/kaspad/issues/1499),
 		// this error should be returned rather the logged
-		log.Errorf("no header-only blocks between %s and %s",
+		log.Errorf("No header-only blocks between %s and %s",
 			lowHash, highHash)
 	}
 

domain/consensus/processes/syncmanager/syncmanager.go

@@ -4,6 +4,7 @@ import (
 	"github.com/kaspanet/kaspad/domain/consensus/model"
 	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
 	"github.com/kaspanet/kaspad/infrastructure/logger"
+	"github.com/pkg/errors"
 )
 
 type syncManager struct {
@@ -69,6 +70,21 @@ func (sm *syncManager) GetHashesBetween(stagingArea *model.StagingArea, lowHash,
 	return sm.antiPastHashesBetween(stagingArea, lowHash, highHash, maxBlocks)
 }
 
+func (sm *syncManager) GetAnticone(stagingArea *model.StagingArea, blockHash, contextHash *externalapi.DomainHash, maxBlocks uint64) (hashes []*externalapi.DomainHash, err error) {
+	onEnd := logger.LogAndMeasureExecutionTime(log, "GetAnticone")
+	defer onEnd()
+	isContextAncestorOfBlock, err := sm.dagTopologyManager.IsAncestorOf(stagingArea, contextHash, blockHash)
+	if err != nil {
+		return nil, err
+	}
+	if isContextAncestorOfBlock {
+		return nil, errors.Errorf("expected block %s to not be in future of %s",
+			blockHash,
+			contextHash)
+	}
+	return sm.dagTraversalManager.AnticoneFromBlocks(stagingArea, []*externalapi.DomainHash{contextHash}, blockHash, maxBlocks)
+}
+
 func (sm *syncManager) GetMissingBlockBodyHashes(stagingArea *model.StagingArea, highHash *externalapi.DomainHash) ([]*externalapi.DomainHash, error) {
 	onEnd := logger.LogAndMeasureExecutionTime(log, "GetMissingBlockBodyHashes")
 	defer onEnd()

domain/consensus/test_consensus.go

@@ -2,6 +2,9 @@ package consensus
 
 import (
 	"encoding/json"
+	"fmt"
+	"github.com/kaspanet/kaspad/domain/consensus/model"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/hashset"
 	"io"
 
 	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
@@ -108,13 +111,13 @@ func (tc *testConsensus) AddUTXOInvalidBlock(parentHashes []*externalapi.DomainH
 	return consensushashing.BlockHash(block), virtualChangeSet, nil
 }
 
-func (tc *testConsensus) MineJSON(r io.Reader, blockType testapi.MineJSONBlockType) (tips []*externalapi.DomainHash, err error) {
-	// jsonBlock is a json representation of a block in mine format
-	type jsonBlock struct {
-		ID      string   `json:"id"`
-		Parents []string `json:"parents"`
-	}
+// jsonBlock is a json representation of a block in mine format
+type jsonBlock struct {
+	ID      string   `json:"id"`
+	Parents []string `json:"parents"`
+}
 
+func (tc *testConsensus) MineJSON(r io.Reader, blockType testapi.MineJSONBlockType) (tips []*externalapi.DomainHash, err error) {
 	tipSet := map[externalapi.DomainHash]*externalapi.DomainHash{}
 	tipSet[*tc.dagParams.GenesisHash] = tc.dagParams.GenesisHash
 
@@ -182,6 +185,64 @@ func (tc *testConsensus) MineJSON(r io.Reader, blockType testapi.MineJSONBlockTy
 	return tips, nil
 }
 
+func (tc *testConsensus) ToJSON(w io.Writer) error {
+	hashToID := make(map[externalapi.DomainHash]string)
+	lastID := 0
+
+	encoder := json.NewEncoder(w)
+	visited := hashset.New()
+	queue := tc.dagTraversalManager.NewUpHeap(model.NewStagingArea())
+	err := queue.Push(tc.dagParams.GenesisHash)
+	if err != nil {
+		return err
+	}
+
+	blocksToAdd := make([]jsonBlock, 0)
+	for queue.Len() > 0 {
+		current := queue.Pop()
+		if visited.Contains(current) {
+			continue
+		}
+
+		visited.Add(current)
+
+		if current.Equal(model.VirtualBlockHash) {
+			continue
+		}
+
+		header, err := tc.blockHeaderStore.BlockHeader(tc.databaseContext, model.NewStagingArea(), current)
+		if err != nil {
+			return err
+		}
+
+		directParents := header.DirectParents()
+
+		parentIDs := make([]string, len(directParents))
+		for i, parent := range directParents {
+			parentIDs[i] = hashToID[*parent]
+		}
+		lastIDStr := fmt.Sprintf("%d", lastID)
+		blocksToAdd = append(blocksToAdd, jsonBlock{
+			ID:      lastIDStr,
+			Parents: parentIDs,
+		})
+		hashToID[*current] = lastIDStr
+		lastID++
+
+		children, err := tc.dagTopologyManagers[0].Children(model.NewStagingArea(), current)
+		if err != nil {
+			return err
+		}
+
+		err = queue.PushSlice(children)
+		if err != nil {
+			return err
+		}
+	}
+
+	return encoder.Encode(blocksToAdd)
+}
+
 func (tc *testConsensus) BuildUTXOInvalidBlock(parentHashes []*externalapi.DomainHash) (*externalapi.DomainBlock, error) {
 	// Require write lock because BuildBlockWithParents stages temporary data
 	tc.lock.Lock()

domain/consensus/utils/blockheader/blockheader.go

@@ -179,9 +179,9 @@ func (bh *blockHeader) ToMutable() externalapi.MutableBlockHeader {
 	return bh.clone()
 }
 
-func (bh *blockHeader) BlockLevel() int {
+func (bh *blockHeader) BlockLevel(maxBlockLevel int) int {
 	if !bh.isBlockLevelCached {
-		bh.blockLevel = pow.BlockLevel(bh)
+		bh.blockLevel = pow.BlockLevel(bh, maxBlockLevel)
 		bh.isBlockLevelCached = true
 	}
 

domain/consensus/utils/constants/constants.go

@@ -35,9 +35,4 @@ const (
 	// LockTimeThreshold is the number below which a lock time is
 	// interpreted to be a DAA score.
 	LockTimeThreshold = 5e11 // Tue Nov 5 00:53:20 1985 UTC
-
-	// MaxBlockLevel is the maximum possible block level.
-	// This is technically 255, but we clamped it at 256 - block level of mainnet genesis
-	// This means that any block that has a level lower or equal to genesis will be level 0.
-	MaxBlockLevel = 225
 )

domain/consensus/utils/lrucachehashandwindowsizetoblockghostdagdatahashpairs/lrucachehashandwindowsizetoblockghostdagdatahashpairs.go

@@ -0,0 +1,79 @@
+package lrucachehashandwindowsizetoblockghostdagdatahashpairs
+
+import "github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+
+type lruKey struct {
+	blockHash  externalapi.DomainHash
+	windowSize int
+}
+
+func newKey(blockHash *externalapi.DomainHash, windowSize int) lruKey {
+	return lruKey{
+		blockHash:  *blockHash,
+		windowSize: windowSize,
+	}
+}
+
+// LRUCache is a least-recently-used cache from
+// lruKey to *externalapi.BlockGHOSTDAGDataHashPair
+type LRUCache struct {
+	cache    map[lruKey][]*externalapi.BlockGHOSTDAGDataHashPair
+	capacity int
+}
+
+// New creates a new LRUCache
+func New(capacity int, preallocate bool) *LRUCache {
+	var cache map[lruKey][]*externalapi.BlockGHOSTDAGDataHashPair
+	if preallocate {
+		cache = make(map[lruKey][]*externalapi.BlockGHOSTDAGDataHashPair, capacity+1)
+	} else {
+		cache = make(map[lruKey][]*externalapi.BlockGHOSTDAGDataHashPair)
+	}
+	return &LRUCache{
+		cache:    cache,
+		capacity: capacity,
+	}
+}
+
+// Add adds an entry to the LRUCache
+func (c *LRUCache) Add(blockHash *externalapi.DomainHash, windowSize int, value []*externalapi.BlockGHOSTDAGDataHashPair) {
+	key := newKey(blockHash, windowSize)
+	c.cache[key] = value
+
+	if len(c.cache) > c.capacity {
+		c.evictRandom()
+	}
+}
+
+// Get returns the entry for the given key, or (nil, false) otherwise
+func (c *LRUCache) Get(blockHash *externalapi.DomainHash, windowSize int) ([]*externalapi.BlockGHOSTDAGDataHashPair, bool) {
+	key := newKey(blockHash, windowSize)
+	value, ok := c.cache[key]
+	if !ok {
+		return nil, false
+	}
+	return value, true
+}
+
+// Has returns whether the LRUCache contains the given key
+func (c *LRUCache) Has(blockHash *externalapi.DomainHash, windowSize int) bool {
+	key := newKey(blockHash, windowSize)
+	_, ok := c.cache[key]
+	return ok
+}
+
+// Remove removes the entry for the the given key. Does nothing if
+// the entry does not exist
+func (c *LRUCache) Remove(blockHash *externalapi.DomainHash, windowSize int) {
+	key := newKey(blockHash, windowSize)
+	delete(c.cache, key)
+}
+
+func (c *LRUCache) evictRandom() {
+	var keyToEvict lruKey
+	for key := range c.cache {
+		keyToEvict = key
+		break
+	}
+	c.Remove(&keyToEvict.blockHash, keyToEvict.windowSize)
+}

domain/consensus/utils/pow/pow.go

@@ -3,7 +3,6 @@ package pow
 import (
 	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
 	"github.com/kaspanet/kaspad/domain/consensus/utils/consensushashing"
-	"github.com/kaspanet/kaspad/domain/consensus/utils/constants"
 	"github.com/kaspanet/kaspad/domain/consensus/utils/hashes"
 	"github.com/kaspanet/kaspad/domain/consensus/utils/serialization"
 	"github.com/kaspanet/kaspad/util/difficulty"
@@ -96,15 +95,15 @@ func toBig(hash *externalapi.DomainHash) *big.Int {
 }
 
 // BlockLevel returns the block level of the given header.
-func BlockLevel(header externalapi.BlockHeader) int {
+func BlockLevel(header externalapi.BlockHeader, maxBlockLevel int) int {
 	// Genesis is defined to be the root of all blocks at all levels, so we define it to be the maximal
 	// block level.
 	if len(header.DirectParents()) == 0 {
-		return constants.MaxBlockLevel
+		return maxBlockLevel
 	}
 
 	proofOfWorkValue := NewState(header.ToMutable()).CalculateProofOfWorkValue()
-	level := constants.MaxBlockLevel - proofOfWorkValue.BitLen()
+	level := maxBlockLevel - proofOfWorkValue.BitLen()
 	// If the block has a level lower than genesis make it zero.
 	if level < 0 {
 		level = 0

domain/dagconfig/params.go

@@ -185,6 +185,9 @@ type Params struct {
 	DisallowDirectBlocksOnTopOfGenesis bool
 
 	IgnoreHeaderMass bool
+
+	// MaxBlockLevel is the maximum possible block level.
+	MaxBlockLevel int
 }
 
 // NormalizeRPCServerAddress returns addr with the current network default
@@ -279,16 +282,20 @@ var MainnetParams = Params{
 	PruningProofM:                           defaultPruningProofM,
 	DeflationaryPhaseDaaScore:               defaultDeflationaryPhaseDaaScore,
 	DisallowDirectBlocksOnTopOfGenesis:      true,
+
+	// This is technically 255, but we clamped it at 256 - block level of mainnet genesis
+	// This means that any block that has a level lower or equal to genesis will be level 0.
+	MaxBlockLevel: 225,
 }
 
 // TestnetParams defines the network parameters for the test Kaspa network.
 var TestnetParams = Params{
 	K:           defaultGHOSTDAGK,
-	Name:        "kaspa-testnet-8",
+	Name:        "kaspa-testnet-9",
 	Net:         appmessage.Testnet,
 	RPCPort:     "16210",
 	DefaultPort: "16211",
-	DNSSeeds:    []string{"testnet-8-dnsseed.daglabs-dev.com"},
+	DNSSeeds:    []string{"testnet-9-dnsseed.daglabs-dev.com"},
 
 	// DAG parameters
 	GenesisBlock:                    &testnetGenesisBlock,
@@ -339,6 +346,8 @@ var TestnetParams = Params{
 	PruningProofM:                           defaultPruningProofM,
 	DeflationaryPhaseDaaScore:               defaultDeflationaryPhaseDaaScore,
 	IgnoreHeaderMass:                        true,
+
+	MaxBlockLevel: 250,
 }
 
 // SimnetParams defines the network parameters for the simulation test Kaspa
@@ -402,6 +411,8 @@ var SimnetParams = Params{
 	CoinbasePayloadScriptPublicKeyMaxLength: defaultCoinbasePayloadScriptPublicKeyMaxLength,
 	PruningProofM:                           defaultPruningProofM,
 	DeflationaryPhaseDaaScore:               defaultDeflationaryPhaseDaaScore,
+
+	MaxBlockLevel: 250,
 }
 
 // DevnetParams defines the network parameters for the development Kaspa network.
@@ -462,6 +473,8 @@ var DevnetParams = Params{
 	PruningProofM:                           defaultPruningProofM,
 	DeflationaryPhaseDaaScore:               defaultDeflationaryPhaseDaaScore,
 	IgnoreHeaderMass:                        true,
+
+	MaxBlockLevel: 250,
 }
 
 // ErrDuplicateNet describes an error where the parameters for a Kaspa

domain/miningmanager/blocktemplatebuilder/blocktemplatebuilder.go

@@ -135,7 +135,7 @@ func (btb *blockTemplateBuilder) GetBlockTemplate(coinbaseData *consensusexterna
 
 	invalidTxsErr := ruleerrors.ErrInvalidTransactionsInNewBlock{}
 	if errors.As(err, &invalidTxsErr) {
-		log.Criticalf("consensusReference.Consensus().BuildBlock returned invalid txs in GetBlockTemplate: %s", err)
+		log.Criticalf("consensusReference.Consensus().BuildBlock returned invalid txs in GetBlockTemplate")
 		invalidTxs := make([]*consensusexternalapi.DomainTransaction, 0, len(invalidTxsErr.InvalidTransactions))
 		for _, tx := range invalidTxsErr.InvalidTransactions {
 			invalidTxs = append(invalidTxs, tx.Transaction)

domain/miningmanager/mempool/model/ordered_transactions_by_fee_rate.go

@@ -18,7 +18,7 @@ func (tobf *TransactionsOrderedByFeeRate) GetByIndex(index int) *MempoolTransact
 
 // Push inserts a transaction into the set, placing it in the correct place to preserve order
 func (tobf *TransactionsOrderedByFeeRate) Push(transaction *MempoolTransaction) error {
-	index, err := tobf.findTransactionIndex(transaction)
+	index, _, err := tobf.findTransactionIndex(transaction)
 	if err != nil {
 		return err
 	}
@@ -29,18 +29,21 @@ func (tobf *TransactionsOrderedByFeeRate) Push(transaction *MempoolTransaction)
 	return nil
 }
 
+// ErrTransactionNotFound  is returned bt tobf.TransactionsOrderedByFeeRate
+var ErrTransactionNotFound = errors.New("Couldn't find transaction in mp.orderedTransactionsByFeeRate")
+
 // Remove removes the given transaction from the set.
 // Returns an error if transaction does not exist in the set, or if the given transaction does not have mass
 // and fee filled in.
 func (tobf *TransactionsOrderedByFeeRate) Remove(transaction *MempoolTransaction) error {
-	index, err := tobf.findTransactionIndex(transaction)
+	index, wasFound, err := tobf.findTransactionIndex(transaction)
 	if err != nil {
 		return err
 	}
 
-	txID := transaction.TransactionID()
-	if !tobf.slice[index].TransactionID().Equal(txID) {
-		return errors.Errorf("Couldn't find %s in mp.orderedTransactionsByFeeRate", txID)
+	if !wasFound {
+		return errors.Wrapf(ErrTransactionNotFound,
+			"Couldn't find %s in mp.orderedTransactionsByFeeRate", transaction.TransactionID())
 	}
 
 	return tobf.RemoveAtIndex(index)
@@ -56,15 +59,18 @@ func (tobf *TransactionsOrderedByFeeRate) RemoveAtIndex(index int) error {
 	return nil
 }
 
-func (tobf *TransactionsOrderedByFeeRate) findTransactionIndex(transaction *MempoolTransaction) (int, error) {
+// findTransactionIndex finds the given transaction inside the list of transactions ordered by fee rate.
+// If the transaction was not found, will return wasFound=false and index=the index at which transaction can be inserted
+// while preserving the order.
+func (tobf *TransactionsOrderedByFeeRate) findTransactionIndex(transaction *MempoolTransaction) (index int, wasFound bool, err error) {
 	if transaction.Transaction().Fee == 0 || transaction.Transaction().Mass == 0 {
-		return 0, errors.Errorf("findTxIndexInOrderedTransactionsByFeeRate expects a transaction with " +
+		return 0, false, errors.Errorf("findTransactionIndex expects a transaction with " +
 			"populated fee and mass")
 	}
 	txID := transaction.TransactionID()
 	txFeeRate := float64(transaction.Transaction().Fee) / float64(transaction.Transaction().Mass)
 
-	return sort.Search(len(tobf.slice), func(i int) bool {
+	index = sort.Search(len(tobf.slice), func(i int) bool {
 		iElement := tobf.slice[i]
 		elementFeeRate := float64(iElement.Transaction().Fee) / float64(iElement.Transaction().Mass)
 		if elementFeeRate > txFeeRate {
@@ -76,5 +82,10 @@ func (tobf *TransactionsOrderedByFeeRate) findTransactionIndex(transaction *Memp
 		}
 
 		return false
-	}), nil
+	})
+
+	wasFound = index != len(tobf.slice) && // sort.Search returns len(tobf.slice) if nothing was found
+		tobf.slice[index].TransactionID().Equal(transaction.TransactionID())
+
+	return index, wasFound, nil
 }

domain/miningmanager/mempool/transactions_pool.go

@@ -3,6 +3,8 @@ package mempool
 import (
 	"time"
 
+	"github.com/pkg/errors"
+
 	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
 	"github.com/kaspanet/kaspad/domain/miningmanager/mempool/model"
 )
@@ -79,7 +81,12 @@ func (tp *transactionsPool) removeTransaction(transaction *model.MempoolTransact
 
 	err := tp.transactionsOrderedByFeeRate.Remove(transaction)
 	if err != nil {
-		return err
+		if errors.Is(err, model.ErrTransactionNotFound) {
+			log.Errorf("Transaction %s not found in tp.transactionsOrderedByFeeRate. This should never happen but sometime does",
+				transaction.TransactionID())
+		} else {
+			return err
+		}
 	}
 
 	delete(tp.highPriorityTransactions, *transaction.TransactionID())

infrastructure/config/config.go

@@ -52,7 +52,7 @@ const (
 	defaultSigCacheMaxSize  = 100000
 	sampleConfigFilename    = "sample-kaspad.conf"
 	defaultMaxUTXOCacheSize = 5000000000
-	defaultProtocolVersion  = 4
+	defaultProtocolVersion  = 5
 )
 
 var (

infrastructure/network/netadapter/server/grpcserver/protowire/messages.proto

@@ -47,6 +47,10 @@ message KaspadMessage {
     ReadyMessage ready = 50;
     BlockWithTrustedDataV4Message blockWithTrustedDataV4 = 51;
     TrustedDataMessage trustedData = 52;
+    RequestIBDChainBlockLocatorMessage requestIBDChainBlockLocator = 53;
+    IbdChainBlockLocatorMessage ibdChainBlockLocator = 54;
+    RequestAnticoneMessage requestAnticone = 55;
+    RequestNextPruningPointAndItsAnticoneBlocksMessage requestNextPruningPointAndItsAnticoneBlocks = 56;
 
     GetCurrentNetworkRequestMessage getCurrentNetworkRequest = 1001;
     GetCurrentNetworkResponseMessage getCurrentNetworkResponse = 1002;