lnwallet/chanvalidate: update ValidateChannel to recognize taproot chans

lnwallet/chanvalidate/validate.go

@@ -186,10 +186,14 @@ func Validate(ctx *Context) (*wire.OutPoint, error) {
 	// If we reach this point, then all other checks have succeeded, so
 	// we'll now attempt a full Script VM execution to ensure that we're
 	// able to close the channel using this initial state.
+	prevFetcher := txscript.NewCannedPrevOutputFetcher(
+		ctx.MultiSigPkScript, fundingValue,
+	)
+	commitTx := ctx.CommitCtx.FullySignedCommitTx
+	hashCache := txscript.NewTxSigHashes(commitTx, prevFetcher)
 	vm, err := txscript.NewEngine(
-		ctx.MultiSigPkScript, ctx.CommitCtx.FullySignedCommitTx,
+		ctx.MultiSigPkScript, commitTx, 0, txscript.StandardVerifyFlags,
-		0, txscript.StandardVerifyFlags, nil, nil, fundingValue,
+		nil, hashCache, fundingValue, prevFetcher,
-		txscript.NewCannedPrevOutputFetcher(ctx.MultiSigPkScript, 0),
 	)
 	if err != nil {
 		return nil, err

lnwallet/wallet.go

@@ -2433,16 +2433,23 @@ func (l *LightningWallet) ValidateChannel(channelState *channeldb.OpenChannel,
 	if err != nil {
 		return err
 	}
-	signedCommitTx, err := channel.getSignedCommitTx()
+
-	if err != nil {
+	localKey := channelState.LocalChanCfg.MultiSigKey.PubKey
-		return err
+	remoteKey := channelState.RemoteChanCfg.MultiSigKey.PubKey
-	}
 
 	// We'll also need the multi-sig witness script itself so the
 	// chanvalidate package can check it for correctness against the
 	// funding transaction, and also commitment validity.
-	localKey := channelState.LocalChanCfg.MultiSigKey.PubKey
+	var fundingScript []byte
-	remoteKey := channelState.RemoteChanCfg.MultiSigKey.PubKey
+	if channelState.ChanType.IsTaproot() {
+		fundingScript, _, err = input.GenTaprootFundingScript(
+			localKey, remoteKey, int64(channel.Capacity),
+		)
+		if err != nil {
+			return err
+		}
+
+	} else {
 		witnessScript, err := input.GenMultiSigScript(
 			localKey.SerializeCompressed(),
 			remoteKey.SerializeCompressed(),
@@ -2450,10 +2457,20 @@ func (l *LightningWallet) ValidateChannel(channelState *channeldb.OpenChannel,
 		if err != nil {
 			return err
 		}
-	pkScript, err := input.WitnessScriptHash(witnessScript)
+		fundingScript, err = input.WitnessScriptHash(witnessScript)
 		if err != nil {
 			return err
 		}
+	}
+
+	signedCommitTx, err := channel.getSignedCommitTx()
+	if err != nil {
+		return err
+	}
+	commitCtx := &chanvalidate.CommitmentContext{
+		Value:               channel.Capacity,
+		FullySignedCommitTx: signedCommitTx,
+	}
 
 	// Finally, we'll pass in all the necessary context needed to fully
 	// validate that this channel is indeed what we expect, and can be
@@ -2462,12 +2479,9 @@ func (l *LightningWallet) ValidateChannel(channelState *channeldb.OpenChannel,
 		Locator: &chanvalidate.OutPointChanLocator{
 			ChanPoint: channelState.FundingOutpoint,
 		},
-		MultiSigPkScript: pkScript,
+		MultiSigPkScript: fundingScript,
 		FundingTx:        fundingTx,
-		CommitCtx: &chanvalidate.CommitmentContext{
+		CommitCtx:        commitCtx,
-			Value:               channel.Capacity,
-			FullySignedCommitTx: signedCommitTx,
-		},
 	})
 	if err != nil {
 		return err