graph: add channel point to utxo filter

In case we assume valid channels or have alias channels we make
sure we also add the channel point to the block filter so that
we are notified if the channel point is spent in a block.

Author: ziggie1984

graph/builder.go

@@ -1206,6 +1206,16 @@ func (b *Builder) processUpdate(msg interface{},
 				"chan_id=%v", msg.ChannelID)
 		}
 
+		// Look up the funding pk script so that we can register the
+		// channel output in the UTXO filter.
+		fundingPkScript, err := makeFundingScript(
+			msg.BitcoinKey1Bytes[:], msg.BitcoinKey2Bytes[:],
+			msg.Features, msg.TapscriptRoot,
+		)
+		if err != nil {
+			return err
+		}
+
 		// If AssumeChannelValid is present, then we are unable to
 		// perform any of the expensive checks below, so we'll
 		// short-circuit our path straight to adding the edge to our
@@ -1219,10 +1229,44 @@ func (b *Builder) processUpdate(msg interface{},
 			if err != nil {
 				return fmt.Errorf("unable to add edge: %w", err)
 			}
-			log.Tracef("New channel discovered! Link "+
-				"connects %x and %x with ChannelID(%v)",
-				msg.NodeKey1Bytes, msg.NodeKey2Bytes,
-				msg.ChannelID)
+
+			// Use different log levels based on channel type.
+			if b.cfg.IsAlias(scid) {
+				log.Debugf("New alias channel discovered! "+
+					"Link connects %x and %x with "+
+					"ChannelID(%v)", msg.NodeKey1Bytes,
+					msg.NodeKey2Bytes,
+					msg.ChannelID)
+
+				// For alias channels, we make sure we add the
+				// channel to the UTXO filter so that we are
+				// notified if/when this channel is closed.
+				// This is safe because for zeroconf we trust
+				// the funding tx anyway. And for non-zeroconf
+				// alias channel we would only reach this point
+				// if the funding tx is confirmed.
+				//
+				//nolint:ll
+				filterUpdate := []graphdb.EdgePoint{
+					{
+						FundingPkScript: fundingPkScript,
+						OutPoint:        msg.ChannelPoint,
+					},
+				}
+				err = b.cfg.ChainView.UpdateFilter(
+					filterUpdate, b.bestHeight.Load(),
+				)
+				if err != nil {
+					return errors.Errorf("unable to "+
+						"update chain view: %v", err)
+				}
+			} else {
+				log.Tracef("New channel discovered! Link "+
+					"connects %x and %x with ChannelID(%v)",
+					msg.NodeKey1Bytes, msg.NodeKey2Bytes,
+					msg.ChannelID)
+			}
+
 			b.stats.incNumEdgesDiscovered()
 
 			break
@@ -1270,17 +1314,6 @@ func (b *Builder) processUpdate(msg interface{},
 				"locate funding tx: %v", err)
 		}
 
-		// Recreate witness output to be sure that declared in channel
-		// edge bitcoin keys and channel value corresponds to the
-		// reality.
-		fundingPkScript, err := makeFundingScript(
-			msg.BitcoinKey1Bytes[:], msg.BitcoinKey2Bytes[:],
-			msg.Features, msg.TapscriptRoot,
-		)
-		if err != nil {
-			return err
-		}
-
 		// Next we'll validate that this channel is actually well
 		// formed. If this check fails, then this channel either
 		// doesn't exist, or isn't the one that was meant to be created