input+lnwallet: use individual commit weight calculations for channel type

Based on the channel type, the commitment weight will be calculated.

input/size.go

@@ -122,6 +122,12 @@ const (
 	//	- PkScript (P2WPKH)
 	CommitmentKeyHashOutput = 8 + 1 + P2WPKHSize
 
+	// CommitmentAnchorOutput 43 bytes
+	//	- Value: 8 bytes
+	//	- VarInt: 1 byte (PkScript length)
+	//	- PkScript (P2WSH)
+	CommitmentAnchorOutput = 8 + 1 + P2WSHSize
+
 	// HTLCSize 43 bytes
 	//	- Value: 8 bytes
 	//	- VarInt: 1 byte (PkScript length)
@@ -159,9 +165,32 @@ const (
 	// WitnessCommitmentTxWeight 224 weight
 	WitnessCommitmentTxWeight = WitnessHeaderSize + WitnessSize
 
+	// BaseAnchorCommitmentTxSize 225 + 43 * num-htlc-outputs bytes
+	//	- Version: 4 bytes
+	//	- WitnessHeader <---- part of the witness data
+	//	- CountTxIn: 1 byte
+	//	- TxIn: 41 bytes
+	//		FundingInput
+	//	- CountTxOut: 3 byte
+	//	- TxOut: 4*43 + 43 * num-htlc-outputs bytes
+	//		OutputPayingToThem,
+	//		OutputPayingToUs,
+	//		AnchorPayingToThem,
+	//		AnchorPayingToUs,
+	//		....HTLCOutputs...
+	//	- LockTime: 4 bytes
+	BaseAnchorCommitmentTxSize = 4 + 1 + FundingInputSize + 3 +
+		2*CommitmentDelayOutput + 2*CommitmentAnchorOutput + 4
+
+	// BaseAnchorCommitmentTxWeight 900 weight
+	BaseAnchorCommitmentTxWeight = witnessScaleFactor * BaseAnchorCommitmentTxSize
+
 	// CommitWeight 724 weight
 	CommitWeight = BaseCommitmentTxWeight + WitnessCommitmentTxWeight
 
+	// AnchorCommitWeight 1124 weight
+	AnchorCommitWeight = BaseAnchorCommitmentTxWeight + WitnessCommitmentTxWeight
+
 	// HTLCWeight 172 weight
 	HTLCWeight = witnessScaleFactor * HTLCSize
 

lnwallet/channel.go

@@ -3772,7 +3772,8 @@ func (lc *LightningChannel) computeView(view *htlcView, remoteChain bool,
 		totalHtlcWeight += input.HTLCWeight
 	}
 
-	totalCommitWeight := input.CommitWeight + totalHtlcWeight
+	totalCommitWeight := CommitWeight(lc.channelState.ChanType) +
+		totalHtlcWeight
 	return ourBalance, theirBalance, totalCommitWeight, filteredHTLCView, nil
 }
 
@@ -6322,7 +6323,7 @@ func CreateCooperativeCloseTx(fundingTxIn wire.TxIn,
 // CalcFee returns the commitment fee to use for the given
 // fee rate (fee-per-kw).
 func (lc *LightningChannel) CalcFee(feeRate chainfee.SatPerKWeight) btcutil.Amount {
-	return feeRate.FeeForWeight(input.CommitWeight)
+	return feeRate.FeeForWeight(CommitWeight(lc.channelState.ChanType))
 }
 
 // MaxFeeRate returns the maximum fee rate given an allocation of the channel

lnwallet/commitment.go

@@ -224,6 +224,16 @@ func CommitScriptToRemote(chanType channeldb.ChannelType,
 	}, 0, nil
 }
 
+// CommitWeight returns the base commitment weight before adding HTLCs.
+func CommitWeight(chanType channeldb.ChannelType) int64 {
+	// If this commitment has anchors, it will be slightly heavier.
+	if chanType.HasAnchors() {
+		return input.AnchorCommitWeight
+	}
+
+	return input.CommitWeight
+}
+
 // CommitScriptAnchors return the scripts to use for the local and remote
 // anchor.
 func CommitScriptAnchors(localChanCfg,
@@ -364,7 +374,8 @@ func (cb *CommitmentBuilder) createUnsignedCommitmentTx(ourBalance,
 	// on its total weight. Once we have the total weight, we'll multiply
 	// by the current fee-per-kw, then divide by 1000 to get the proper
 	// fee.
-	totalCommitWeight := input.CommitWeight + (input.HTLCWeight * numHTLCs)
+	totalCommitWeight := CommitWeight(cb.chanState.ChanType) +
+		input.HTLCWeight*numHTLCs
 
 	// With the weight known, we can now calculate the commitment fee,
 	// ensuring that we account for any dust outputs trimmed above.