tapchannel: add dust checks for allocations

Author: GeorgeTsagk

tapchannel/commitment.go

@@ -707,6 +707,24 @@ func CreateAllocations(chanState *channeldb.OpenChannel, ourBalance,
 			allocType = CommitAllocationHtlcIncoming
 		}
 
+		dustLimit := chanState.LocalChanCfg.DustLimit
+		if !isOurCommit {
+			dustLimit = chanState.RemoteChanCfg.DustLimit
+		}
+
+		// If HTLC is dust, do not create allocation for it.
+		isDust := lnwallet.HtlcIsDust(
+			chanState.ChanType, isIncoming, isOurCommit,
+			filteredView.FeePerKw, htlc.Amount.ToSatoshis(),
+			dustLimit,
+		)
+		if isDust {
+			// We need to error out, as a dust HTLC carrying assets
+			// should not be expected.
+			return fmt.Errorf("error creating asset HTLC " +
+				"allocation, HTLC is dust")
+		}
+
 		allocations = append(allocations, &Allocation{
 			Type:           allocType,
 			Amount:         rfqmsg.Sum(htlc.AssetBalances),
@@ -773,6 +791,21 @@ func CreateAllocations(chanState *channeldb.OpenChannel, ourBalance,
 				"sibling: %w", err)
 		}
 
+		dustLimit := chanState.LocalChanCfg.DustLimit
+		if !isOurCommit {
+			dustLimit = chanState.RemoteChanCfg.DustLimit
+		}
+
+		// If HTLC is dust, do not create allocation for it.
+		isDust := lnwallet.HtlcIsDust(
+			chanState.ChanType, isIncoming, isOurCommit,
+			filteredView.FeePerKw, htlc.Amount.ToSatoshis(),
+			dustLimit,
+		)
+		if isDust {
+			return nil
+		}
+
 		allocations = append(allocations, &Allocation{
 			Type:           AllocationTypeNoAssets,
 			BtcAmount:      htlc.Amount.ToSatoshis(),