Add DNSSEEDER environment flag in order to ignore blocks and transactions

app/protocol/common/common.go

@@ -3,6 +3,8 @@ package common
 import (
 	peerpkg "github.com/kaspanet/kaspad/app/protocol/peer"
 	routerpkg "github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
+	"os"
+	"sync"
 	"time"
 
 	"github.com/pkg/errors"
@@ -25,3 +27,18 @@ type Flow struct {
 
 // FlowInitializeFunc is a function that is used in order to initialize a flow
 type FlowInitializeFunc func(route *routerpkg.Route, peer *peerpkg.Peer) error
+
+var isDNSSeeder bool
+var isDNSSeederOnce sync.Once
+
+// IsDNSSeeder returns whether this node supports a DNS seeder. If this is the case, the node
+// doesn't need to actually stay synced, and is mainly used for scanning the p2p network.
+func IsDNSSeeder() bool {
+	isDNSSeederOnce.Do(func() {
+		isDNSSeederEnv := os.Getenv("DNSSEEDER")
+		if isDNSSeederEnv != "" {
+			isDNSSeeder = true
+		}
+	})
+	return isDNSSeeder
+}

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

@@ -77,6 +77,11 @@ func (flow *handleRelayInvsFlow) start() error {
 			return err
 		}
 
+		if common.IsDNSSeeder() {
+			log.Debugf("IsDNSSeeder=true so skipping block inv")
+			continue
+		}
+
 		log.Debugf("Got relay inv for block %s", inv.Hash)
 
 		blockInfo, err := flow.Domain().Consensus().GetBlockInfo(inv.Hash)

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

@@ -50,6 +50,11 @@ func (flow *handleRelayedTransactionsFlow) start() error {
 			return err
 		}
 
+		if common.IsDNSSeeder() {
+			log.Debugf("IsDNSSeeder=true so skipping tx inv")
+			continue
+		}
+
 		isNearlySynced, err := flow.IsNearlySynced()
 		if err != nil {
 			return err

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

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