tapchannel: import funding output proofs for responder during co-op close

Otherwise, the transfer insert for the responder may fail as they don't
have the funding output in their database, so shipping the transfer
fails as it can't find the proof.

Fixes #985.

Author: Roasbeef

tapcfg/server.go

@@ -447,6 +447,13 @@ func genServerConfig(cfg *Config, cfgLogger btclog.Logger,
 			AddrBook:           addrBook,
 			TxSender:           chainPorter,
 			DefaultCourierAddr: proofCourierAddr,
+			ProofArchive:       proofArchive,
+			ProofFetcher:       proofCourierDispatcher,
+			HeaderVerifier:     headerVerifier,
+			GroupVerifier: tapgarden.GenGroupVerifier(
+				context.Background(), assetMintingStore,
+			),
+			ChainBridge: chainBridge,
 		},
 	)
 	auxSweeper := tapchannel.NewAuxSweeper(

tapchannel/aux_closer.go

@@ -17,6 +17,7 @@ import (
 	"github.com/lightninglabs/taproot-assets/proof"
 	"github.com/lightninglabs/taproot-assets/tapchannelmsg"
 	"github.com/lightninglabs/taproot-assets/tapfreighter"
+	"github.com/lightninglabs/taproot-assets/tapgarden"
 	"github.com/lightninglabs/taproot-assets/tappsbt"
 	"github.com/lightninglabs/taproot-assets/tapsend"
 	lfn "github.com/lightningnetwork/lnd/fn"
@@ -45,6 +46,22 @@ type AuxChanCloserCfg struct {
 	// DefaultCourierAddr is the default address we'll use to send/receive
 	// proofs for the co-op close process
 	DefaultCourierAddr *url.URL
+
+	// ProofFetcher is used to fetch proofs needed to properly import the
+	// funding output into the database as our own.
+	ProofFetcher proof.CourierDispatch
+
+	// ProofArchive is used to store import funding output proofs.
+	ProofArchive proof.Archiver
+
+	// HeaderVerifier is used to verify headers in a proof.
+	HeaderVerifier proof.HeaderVerifier
+
+	// GroupVerifier is used to verify group keys in a proof.
+	GroupVerifier proof.GroupVerifier
+
+	// ChainBridge is used to fetch blocks from the main chain.
+	ChainBridge tapgarden.ChainBridge
 }
 
 // assetCloseInfo houses the information we need to finalize the close of an
@@ -624,6 +641,37 @@ func (a *AuxChanCloser) FinalizeClose(desc chancloser.AuxCloseDesc,
 			desc.ChanPoint)
 	}
 
+	// Before we finalize the close process, we'll make sure to also import
+	// a transfer for the funding outputs. This way we'll ensure that we're
+	// able to insert the transfer that spends these outputs. We only need
+	// to do this for the responder though, as the creator of the channel
+	// already has these proofs inserted.
+	if !desc.Initiator {
+		fundingInfo, err := tapchannelmsg.DecodeOpenChannel(
+			desc.FundingBlob.UnwrapOr(nil),
+		)
+		if err != nil {
+			return err
+		}
+
+		fundingInputProofs := fn.Map(
+			fundingInfo.FundedAssets.Val.Outputs,
+			func(a *tapchannelmsg.AssetOutput) *proof.Proof {
+				return &a.Proof.Val
+			},
+		)
+		err = importOutputProofs(
+			desc.ShortChanID, fundingInputProofs,
+			a.cfg.DefaultCourierAddr, a.cfg.ProofFetcher,
+			a.cfg.ChainBridge, a.cfg.HeaderVerifier,
+			a.cfg.GroupVerifier, a.cfg.ProofArchive,
+		)
+		if err != nil {
+			return fmt.Errorf("unable to import output "+
+				"proofs: %w", err)
+		}
+	}
+
 	log.Infof("Finalizing close for ChannelPoint(%v): ", desc.ChanPoint)
 
 	defer delete(a.closeInfo, desc.ChanPoint)