Validate GetBlockTemplate extra data (#1997)

* Validate GetBlockTemplate extra data

* Check payload instead of extra data

* Fix error message

app/rpc/rpchandlers/get_block_template.go

@@ -4,6 +4,7 @@ import (
 	"github.com/kaspanet/kaspad/app/appmessage"
 	"github.com/kaspanet/kaspad/app/rpc/rpccontext"
 	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
+	"github.com/kaspanet/kaspad/domain/consensus/utils/transactionhelper"
 	"github.com/kaspanet/kaspad/domain/consensus/utils/txscript"
 	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/router"
 	"github.com/kaspanet/kaspad/util"
@@ -16,7 +17,7 @@ func HandleGetBlockTemplate(context *rpccontext.Context, _ *router.Router, reque
 
 	payAddress, err := util.DecodeAddress(getBlockTemplateRequest.PayAddress, context.Config.ActiveNetParams.Prefix)
 	if err != nil {
-		errorMessage := &appmessage.GetBlockResponseMessage{}
+		errorMessage := &appmessage.GetBlockTemplateResponseMessage{}
 		errorMessage.Error = appmessage.RPCErrorf("Could not decode address: %s", err)
 		return errorMessage, nil
 	}
@@ -27,11 +28,17 @@ func HandleGetBlockTemplate(context *rpccontext.Context, _ *router.Router, reque
 	}
 
 	coinbaseData := &externalapi.DomainCoinbaseData{ScriptPublicKey: scriptPublicKey, ExtraData: []byte(version.Version() + "/" + getBlockTemplateRequest.ExtraData)}
-
 	templateBlock, err := context.Domain.MiningManager().GetBlockTemplate(coinbaseData)
 	if err != nil {
 		return nil, err
 	}
+
+	if uint64(len(templateBlock.Transactions[transactionhelper.CoinbaseTransactionIndex].Payload)) > context.Config.NetParams().MaxCoinbasePayloadLength {
+		errorMessage := &appmessage.GetBlockTemplateResponseMessage{}
+		errorMessage.Error = appmessage.RPCErrorf("Coinbase payload is above max length (%d). Try to shorten the extra data.", context.Config.NetParams().MaxCoinbasePayloadLength)
+		return errorMessage, nil
+	}
+
 	rpcBlock := appmessage.DomainBlockToRPCBlock(templateBlock)
 
 	isSynced, err := context.ProtocolManager.ShouldMine()

infrastructure/network/netadapter/server/grpcserver/protowire/rpc_get_block_template.go

@@ -38,20 +38,52 @@ func (x *KaspadMessage_GetBlockTemplateResponse) toAppMessage() (appmessage.Mess
 }
 
 func (x *KaspadMessage_GetBlockTemplateResponse) fromAppMessage(message *appmessage.GetBlockTemplateResponseMessage) error {
-	x.GetBlockTemplateResponse = &GetBlockTemplateResponseMessage{
+	var err *RPCError
-		Block:    &RpcBlock{},
+	if message.Error != nil {
-		IsSynced: message.IsSynced,
+		err = &RPCError{Message: message.Error.Message}
 	}
-	return x.GetBlockTemplateResponse.Block.fromAppMessage(message.Block)
+
+	var block *RpcBlock
+	if message.Block != nil {
+		protoBlock := &RpcBlock{}
+		err := protoBlock.fromAppMessage(message.Block)
+		if err != nil {
+			return err
+		}
+		block = protoBlock
+	}
+
+	x.GetBlockTemplateResponse = &GetBlockTemplateResponseMessage{
+		Block:    block,
+		IsSynced: message.IsSynced,
+		Error:    err,
+	}
+	return nil
 }
 
 func (x *GetBlockTemplateResponseMessage) toAppMessage() (appmessage.Message, error) {
 	if x == nil {
 		return nil, errors.Wrapf(errorNil, "GetBlockTemplateResponseMessage is nil")
 	}
-	msgBlock, err := x.Block.toAppMessage()
+	var msgBlock *appmessage.RPCBlock
-	if err != nil {
+	if x.Block != nil {
-		return nil, err
+		var err error
+		msgBlock, err = x.Block.toAppMessage()
+		if err != nil {
+			return nil, err
+		}
 	}
-	return appmessage.NewGetBlockTemplateResponseMessage(msgBlock, x.IsSynced), nil
+	var rpcError *appmessage.RPCError
+	if x.Error != nil {
+		var err error
+		rpcError, err = x.Error.toAppMessage()
+		if err != nil {
+			return nil, err
+		}
+	}
+	return &appmessage.GetBlockTemplateResponseMessage{
+		Block:    msgBlock,
+		IsSynced: x.IsSynced,
+		Error:    rpcError,
+	}, nil
 }