Merge pull request #2460 from halseth/max-htlc-size-pickup

Support the max_htlc field from ChannelUpdates

autopilot/graph.go

@@ -227,9 +227,11 @@ func (d *databaseChannelGraph) addRandChannel(node1, node2 *btcec.PublicKey,
 		LastUpdate:                time.Now(),
 		TimeLockDelta:             10,
 		MinHTLC:                   1,
+		MaxHTLC:                   lnwire.NewMSatFromSatoshis(capacity),
 		FeeBaseMSat:               10,
 		FeeProportionalMillionths: 10000,
-		Flags:                     0,
+		MessageFlags:              1,
+		ChannelFlags:              0,
 	}
 
 	if err := d.db.UpdateEdgePolicy(edgePolicy); err != nil {
@@ -241,9 +243,11 @@ func (d *databaseChannelGraph) addRandChannel(node1, node2 *btcec.PublicKey,
 		LastUpdate:                time.Now(),
 		TimeLockDelta:             10,
 		MinHTLC:                   1,
+		MaxHTLC:                   lnwire.NewMSatFromSatoshis(capacity),
 		FeeBaseMSat:               10,
 		FeeProportionalMillionths: 10000,
-		Flags:                     1,
+		MessageFlags:              1,
+		ChannelFlags:              1,
 	}
 	if err := d.db.UpdateEdgePolicy(edgePolicy); err != nil {
 		return nil, nil, err

channeldb/error.go

@@ -97,6 +97,12 @@ var (
 	// ErrNoForwardingEvents is returned in the case that a query fails due
 	// to the log not having any recorded events.
 	ErrNoForwardingEvents = fmt.Errorf("no recorded forwarding events")
+
+	// ErrEdgePolicyOptionalFieldNotFound is an error returned if a channel
+	// policy field is not found in the db even though its message flags
+	// indicate it should be.
+	ErrEdgePolicyOptionalFieldNotFound = fmt.Errorf("optional field not " +
+		"present")
 )
 
 // ErrTooManyExtraOpaqueBytes creates an error which should be returned if the

channeldb/graph.go

@@ -1640,7 +1640,7 @@ func delChannelByEdge(edges *bbolt.Bucket, edgeIndex *bbolt.Bucket,
 func (c *ChannelGraph) UpdateEdgePolicy(edge *ChannelEdgePolicy) error {
 	return c.db.Update(func(tx *bbolt.Tx) error {
 		edges := tx.Bucket(edgeBucket)
-		if edge == nil {
+		if edges == nil {
 			return ErrEdgeNotFound
 		}
 
@@ -1677,7 +1677,7 @@ func updateEdgePolicy(edges, edgeIndex, nodes *bbolt.Bucket,
 	// Depending on the flags value passed above, either the first
 	// or second edge policy is being updated.
 	var fromNode, toNode []byte
-	if edge.Flags&lnwire.ChanUpdateDirection == 0 {
+	if edge.ChannelFlags&lnwire.ChanUpdateDirection == 0 {
 		fromNode = nodeInfo[:33]
 		toNode = nodeInfo[33:66]
 	} else {
@@ -2422,9 +2422,13 @@ type ChannelEdgePolicy struct {
 	// was received.
 	LastUpdate time.Time
 
-	// Flags is a bitfield which signals the capabilities of the channel as
-	// well as the directed edge this update applies to.
-	Flags lnwire.ChanUpdateFlag
+	// MessageFlags is a bitfield which indicates the presence of optional
+	// fields (like max_htlc) in the policy.
+	MessageFlags lnwire.ChanUpdateMsgFlags
+
+	// ChannelFlags is a bitfield which signals the capabilities of the
+	// channel as well as the directed edge this update applies to.
+	ChannelFlags lnwire.ChanUpdateChanFlags
 
 	// TimeLockDelta is the number of blocks this node will subtract from
 	// the expiry of an incoming HTLC. This value expresses the time buffer
@@ -2435,6 +2439,10 @@ type ChannelEdgePolicy struct {
 	// in millisatoshi.
 	MinHTLC lnwire.MilliSatoshi
 
+	// MaxHTLC is the largest value HTLC this node will accept, expressed
+	// in millisatoshi.
+	MaxHTLC lnwire.MilliSatoshi
+
 	// FeeBaseMSat is the base HTLC fee that will be charged for forwarding
 	// ANY HTLC, expressed in mSAT's.
 	FeeBaseMSat lnwire.MilliSatoshi
@@ -3169,54 +3177,15 @@ func putChanEdgePolicy(edges, nodes *bbolt.Bucket, edge *ChannelEdgePolicy,
 	byteOrder.PutUint64(edgeKey[33:], edge.ChannelID)
 
 	var b bytes.Buffer
-
-	err := wire.WriteVarBytes(&b, 0, edge.SigBytes)
-	if err != nil {
-		return err
-	}
-
-	if err := binary.Write(&b, byteOrder, edge.ChannelID); err != nil {
-		return err
-	}
-
-	var scratch [8]byte
-	updateUnix := uint64(edge.LastUpdate.Unix())
-	byteOrder.PutUint64(scratch[:], updateUnix)
-	if _, err := b.Write(scratch[:]); err != nil {
-		return err
-	}
-
-	if err := binary.Write(&b, byteOrder, edge.Flags); err != nil {
-		return err
-	}
-	if err := binary.Write(&b, byteOrder, edge.TimeLockDelta); err != nil {
-		return err
-	}
-	if err := binary.Write(&b, byteOrder, uint64(edge.MinHTLC)); err != nil {
-		return err
-	}
-	if err := binary.Write(&b, byteOrder, uint64(edge.FeeBaseMSat)); err != nil {
-		return err
-	}
-	if err := binary.Write(&b, byteOrder, uint64(edge.FeeProportionalMillionths)); err != nil {
-		return err
-	}
-
-	if _, err := b.Write(to); err != nil {
-		return err
-	}
-
-	if len(edge.ExtraOpaqueData) > MaxAllowedExtraOpaqueBytes {
-		return ErrTooManyExtraOpaqueBytes(len(edge.ExtraOpaqueData))
-	}
-	if err := wire.WriteVarBytes(&b, 0, edge.ExtraOpaqueData); err != nil {
+	if err := serializeChanEdgePolicy(&b, edge, to); err != nil {
 		return err
 	}
 
 	// Before we write out the new edge, we'll create a new entry in the
 	// update index in order to keep it fresh.
+	updateUnix := uint64(edge.LastUpdate.Unix())
 	var indexKey [8 + 8]byte
-	copy(indexKey[:], scratch[:])
+	byteOrder.PutUint64(indexKey[:8], updateUnix)
 	byteOrder.PutUint64(indexKey[8:], edge.ChannelID)
 
 	updateIndex, err := edges.CreateBucketIfNotExists(edgeUpdateIndexBucket)
@@ -3235,11 +3204,15 @@ func putChanEdgePolicy(edges, nodes *bbolt.Bucket, edge *ChannelEdgePolicy,
 		// *prior* update time in order to delete it. To do this, we'll
 		// need to deserialize the existing policy within the database
 		// (now outdated by the new one), and delete its corresponding
-		// entry within the update index.
+		// entry within the update index. We'll ignore any
+		// ErrEdgePolicyOptionalFieldNotFound error, as we only need
+		// the channel ID and update time to delete the entry.
+		// TODO(halseth): get rid of these invalid policies in a
+		// migration.
 		oldEdgePolicy, err := deserializeChanEdgePolicy(
 			bytes.NewReader(edgeBytes), nodes,
 		)
-		if err != nil {
+		if err != nil && err != ErrEdgePolicyOptionalFieldNotFound {
 			return err
 		}
 
@@ -3297,7 +3270,18 @@ func fetchChanEdgePolicy(edges *bbolt.Bucket, chanID []byte,
 
 	edgeReader := bytes.NewReader(edgeBytes)
 
-	return deserializeChanEdgePolicy(edgeReader, nodes)
+	ep, err := deserializeChanEdgePolicy(edgeReader, nodes)
+	switch {
+	// If the db policy was missing an expected optional field, we return
+	// nil as if the policy was unknown.
+	case err == ErrEdgePolicyOptionalFieldNotFound:
+		return nil, nil
+
+	case err != nil:
+		return nil, err
+	}
+
+	return ep, nil
 }
 
 func fetchChanEdgePolicies(edgeIndex *bbolt.Bucket, edges *bbolt.Bucket,
@@ -3341,6 +3325,73 @@ func fetchChanEdgePolicies(edgeIndex *bbolt.Bucket, edges *bbolt.Bucket,
 	return edge1, edge2, nil
 }
 
+func serializeChanEdgePolicy(w io.Writer, edge *ChannelEdgePolicy,
+	to []byte) error {
+
+	err := wire.WriteVarBytes(w, 0, edge.SigBytes)
+	if err != nil {
+		return err
+	}
+
+	if err := binary.Write(w, byteOrder, edge.ChannelID); err != nil {
+		return err
+	}
+
+	var scratch [8]byte
+	updateUnix := uint64(edge.LastUpdate.Unix())
+	byteOrder.PutUint64(scratch[:], updateUnix)
+	if _, err := w.Write(scratch[:]); err != nil {
+		return err
+	}
+
+	if err := binary.Write(w, byteOrder, edge.MessageFlags); err != nil {
+		return err
+	}
+	if err := binary.Write(w, byteOrder, edge.ChannelFlags); err != nil {
+		return err
+	}
+	if err := binary.Write(w, byteOrder, edge.TimeLockDelta); err != nil {
+		return err
+	}
+	if err := binary.Write(w, byteOrder, uint64(edge.MinHTLC)); err != nil {
+		return err
+	}
+	if err := binary.Write(w, byteOrder, uint64(edge.FeeBaseMSat)); err != nil {
+		return err
+	}
+	if err := binary.Write(w, byteOrder, uint64(edge.FeeProportionalMillionths)); err != nil {
+		return err
+	}
+
+	if _, err := w.Write(to); err != nil {
+		return err
+	}
+
+	// If the max_htlc field is present, we write it. To be compatible with
+	// older versions that wasn't aware of this field, we write it as part
+	// of the opaque data.
+	// TODO(halseth): clean up when moving to TLV.
+	var opaqueBuf bytes.Buffer
+	if edge.MessageFlags.HasMaxHtlc() {
+		err := binary.Write(&opaqueBuf, byteOrder, uint64(edge.MaxHTLC))
+		if err != nil {
+			return err
+		}
+	}
+
+	if len(edge.ExtraOpaqueData) > MaxAllowedExtraOpaqueBytes {
+		return ErrTooManyExtraOpaqueBytes(len(edge.ExtraOpaqueData))
+	}
+	if _, err := opaqueBuf.Write(edge.ExtraOpaqueData); err != nil {
+		return err
+	}
+
+	if err := wire.WriteVarBytes(w, 0, opaqueBuf.Bytes()); err != nil {
+		return err
+	}
+	return nil
+}
+
 func deserializeChanEdgePolicy(r io.Reader,
 	nodes *bbolt.Bucket) (*ChannelEdgePolicy, error) {
 
@@ -3363,7 +3414,10 @@ func deserializeChanEdgePolicy(r io.Reader,
 	unix := int64(byteOrder.Uint64(scratch[:]))
 	edge.LastUpdate = time.Unix(unix, 0)
 
-	if err := binary.Read(r, byteOrder, &edge.Flags); err != nil {
+	if err := binary.Read(r, byteOrder, &edge.MessageFlags); err != nil {
+		return nil, err
+	}
+	if err := binary.Read(r, byteOrder, &edge.ChannelFlags); err != nil {
 		return nil, err
 	}
 	if err := binary.Read(r, byteOrder, &edge.TimeLockDelta); err != nil {
@@ -3396,6 +3450,7 @@ func deserializeChanEdgePolicy(r io.Reader,
 		return nil, fmt.Errorf("unable to fetch node: %x, %v",
 			pub[:], err)
 	}
+	edge.Node = &node
 
 	// We'll try and see if there are any opaque bytes left, if not, then
 	// we'll ignore the EOF error and return the edge as is.
@@ -3409,6 +3464,25 @@ func deserializeChanEdgePolicy(r io.Reader,
 		return nil, err
 	}
 
-	edge.Node = &node
+	// See if optional fields are present.
+	if edge.MessageFlags.HasMaxHtlc() {
+		// The max_htlc field should be at the beginning of the opaque
+		// bytes.
+		opq := edge.ExtraOpaqueData
+
+		// If the max_htlc field is not present, it might be old data
+		// stored before this field was validated. We'll return the
+		// edge along with an error.
+		if len(opq) < 8 {
+			return edge, ErrEdgePolicyOptionalFieldNotFound
+		}
+
+		maxHtlc := byteOrder.Uint64(opq[:8])
+		edge.MaxHTLC = lnwire.MilliSatoshi(maxHtlc)
+
+		// Exclude the parsed field from the rest of the opaque data.
+		edge.ExtraOpaqueData = opq[8:]
+	}
+
 	return edge, nil
 }

channeldb/graph_test.go

@@ -622,33 +622,8 @@ func assertEdgeInfoEqual(t *testing.T, e1 *ChannelEdgeInfo,
 	}
 }
 
-func TestEdgeInfoUpdates(t *testing.T) {
-	t.Parallel()
-
-	db, cleanUp, err := makeTestDB()
-	defer cleanUp()
-	if err != nil {
-		t.Fatalf("unable to make test database: %v", err)
-	}
-
-	graph := db.ChannelGraph()
-
-	// We'd like to test the update of edges inserted into the database, so
-	// we create two vertexes to connect.
-	node1, err := createTestVertex(db)
-	if err != nil {
-		t.Fatalf("unable to create test node: %v", err)
-	}
-	if err := graph.AddLightningNode(node1); err != nil {
-		t.Fatalf("unable to add node: %v", err)
-	}
-	node2, err := createTestVertex(db)
-	if err != nil {
-		t.Fatalf("unable to create test node: %v", err)
-	}
-	if err := graph.AddLightningNode(node2); err != nil {
-		t.Fatalf("unable to add node: %v", err)
-	}
+func createChannelEdge(db *DB, node1, node2 *LightningNode) (*ChannelEdgeInfo,
+	*ChannelEdgePolicy, *ChannelEdgePolicy) {
 
 	var (
 		firstNode  *LightningNode
@@ -689,19 +664,16 @@ func TestEdgeInfoUpdates(t *testing.T) {
 	copy(edgeInfo.NodeKey2Bytes[:], secondNode.PubKeyBytes[:])
 	copy(edgeInfo.BitcoinKey1Bytes[:], firstNode.PubKeyBytes[:])
 	copy(edgeInfo.BitcoinKey2Bytes[:], secondNode.PubKeyBytes[:])
-	if err := graph.AddChannelEdge(edgeInfo); err != nil {
-		t.Fatalf("unable to create channel edge: %v", err)
-	}
 
-	// With the edge added, we can now create some fake edge information to
-	// update for both edges.
 	edge1 := &ChannelEdgePolicy{
 		SigBytes:                  testSig.Serialize(),
 		ChannelID:                 chanID,
 		LastUpdate:                time.Unix(433453, 0),
-		Flags:                     0,
+		MessageFlags:              1,
+		ChannelFlags:              0,
 		TimeLockDelta:             99,
 		MinHTLC:                   2342135,
+		MaxHTLC:                   13928598,
 		FeeBaseMSat:               4352345,
 		FeeProportionalMillionths: 3452352,
 		Node:                      secondNode,
@@ -712,9 +684,11 @@ func TestEdgeInfoUpdates(t *testing.T) {
 		SigBytes:                  testSig.Serialize(),
 		ChannelID:                 chanID,
 		LastUpdate:                time.Unix(124234, 0),
-		Flags:                     1,
+		MessageFlags:              1,
+		ChannelFlags:              1,
 		TimeLockDelta:             99,
 		MinHTLC:                   2342135,
+		MaxHTLC:                   13928598,
 		FeeBaseMSat:               4352345,
 		FeeProportionalMillionths: 90392423,
 		Node:                      firstNode,
@@ -722,8 +696,48 @@ func TestEdgeInfoUpdates(t *testing.T) {
 		db:                        db,
 	}
 
-	// Next, insert both nodes into the database, they should both be
-	// inserted without any issues.
+	return edgeInfo, edge1, edge2
+}
+
+func TestEdgeInfoUpdates(t *testing.T) {
+	t.Parallel()
+
+	db, cleanUp, err := makeTestDB()
+	defer cleanUp()
+	if err != nil {
+		t.Fatalf("unable to make test database: %v", err)
+	}
+
+	graph := db.ChannelGraph()
+
+	// We'd like to test the update of edges inserted into the database, so
+	// we create two vertexes to connect.
+	node1, err := createTestVertex(db)
+	if err != nil {
+		t.Fatalf("unable to create test node: %v", err)
+	}
+	if err := graph.AddLightningNode(node1); err != nil {
+		t.Fatalf("unable to add node: %v", err)
+	}
+	node2, err := createTestVertex(db)
+	if err != nil {
+		t.Fatalf("unable to create test node: %v", err)
+	}
+	if err := graph.AddLightningNode(node2); err != nil {
+		t.Fatalf("unable to add node: %v", err)
+	}
+
+	// Create an edge and add it to the db.
+	edgeInfo, edge1, edge2 := createChannelEdge(db, node1, node2)
+	if err := graph.AddChannelEdge(edgeInfo); err != nil {
+		t.Fatalf("unable to create channel edge: %v", err)
+	}
+
+	chanID := edgeInfo.ChannelID
+	outpoint := edgeInfo.ChannelPoint
+
+	// Next, insert both edge policies into the database, they should both
+	// be inserted without any issues.
 	if err := graph.UpdateEdgePolicy(edge1); err != nil {
 		t.Fatalf("unable to update edge: %v", err)
 	}
@@ -792,8 +806,11 @@ func newEdgePolicy(chanID uint64, op wire.OutPoint, db *DB,
 	return &ChannelEdgePolicy{
 		ChannelID:                 chanID,
 		LastUpdate:                time.Unix(updateTime, 0),
+		MessageFlags:              1,
+		ChannelFlags:              0,
 		TimeLockDelta:             uint16(prand.Int63()),
 		MinHTLC:                   lnwire.MilliSatoshi(prand.Int63()),
+		MaxHTLC:                   lnwire.MilliSatoshi(prand.Int63()),
 		FeeBaseMSat:               lnwire.MilliSatoshi(prand.Int63()),
 		FeeProportionalMillionths: lnwire.MilliSatoshi(prand.Int63()),
 		db:                        db,
@@ -894,7 +911,7 @@ func TestGraphTraversal(t *testing.T) {
 		// Create and add an edge with random data that points from
 		// node1 -> node2.
 		edge := randEdgePolicy(chanID, op, db)
-		edge.Flags = 0
+		edge.ChannelFlags = 0
 		edge.Node = secondNode
 		edge.SigBytes = testSig.Serialize()
 		if err := graph.UpdateEdgePolicy(edge); err != nil {
@@ -904,7 +921,7 @@ func TestGraphTraversal(t *testing.T) {
 		// Create another random edge that points from node2 -> node1
 		// this time.
 		edge = randEdgePolicy(chanID, op, db)
-		edge.Flags = 1
+		edge.ChannelFlags = 1
 		edge.Node = firstNode
 		edge.SigBytes = testSig.Serialize()
 		if err := graph.UpdateEdgePolicy(edge); err != nil {
@@ -1145,7 +1162,7 @@ func TestGraphPruning(t *testing.T) {
 		// Create and add an edge with random data that points from
 		// node_i -> node_i+1
 		edge := randEdgePolicy(chanID, op, db)
-		edge.Flags = 0
+		edge.ChannelFlags = 0
 		edge.Node = graphNodes[i]
 		edge.SigBytes = testSig.Serialize()
 		if err := graph.UpdateEdgePolicy(edge); err != nil {
@@ -1155,7 +1172,7 @@ func TestGraphPruning(t *testing.T) {
 		// Create another random edge that points from node_i+1 ->
 		// node_i this time.
 		edge = randEdgePolicy(chanID, op, db)
-		edge.Flags = 1
+		edge.ChannelFlags = 1
 		edge.Node = graphNodes[i]
 		edge.SigBytes = testSig.Serialize()
 		if err := graph.UpdateEdgePolicy(edge); err != nil {
@@ -1414,7 +1431,7 @@ func TestChanUpdatesInHorizon(t *testing.T) {
 		edge1 := newEdgePolicy(
 			chanID.ToUint64(), op, db, edge1UpdateTime.Unix(),
 		)
-		edge1.Flags = 0
+		edge1.ChannelFlags = 0
 		edge1.Node = node2
 		edge1.SigBytes = testSig.Serialize()
 		if err := graph.UpdateEdgePolicy(edge1); err != nil {
@@ -1424,7 +1441,7 @@ func TestChanUpdatesInHorizon(t *testing.T) {
 		edge2 := newEdgePolicy(
 			chanID.ToUint64(), op, db, edge2UpdateTime.Unix(),
 		)
-		edge2.Flags = 1
+		edge2.ChannelFlags = 1
 		edge2.Node = node1
 		edge2.SigBytes = testSig.Serialize()
 		if err := graph.UpdateEdgePolicy(edge2); err != nil {
@@ -1915,7 +1932,7 @@ func TestFetchChanInfos(t *testing.T) {
 		edge1 := newEdgePolicy(
 			chanID.ToUint64(), op, db, updateTime.Unix(),
 		)
-		edge1.Flags = 0
+		edge1.ChannelFlags = 0
 		edge1.Node = node2
 		edge1.SigBytes = testSig.Serialize()
 		if err := graph.UpdateEdgePolicy(edge1); err != nil {
@@ -1925,7 +1942,7 @@ func TestFetchChanInfos(t *testing.T) {
 		edge2 := newEdgePolicy(
 			chanID.ToUint64(), op, db, updateTime.Unix(),
 		)
-		edge2.Flags = 1
+		edge2.ChannelFlags = 1
 		edge2.Node = node1
 		edge2.SigBytes = testSig.Serialize()
 		if err := graph.UpdateEdgePolicy(edge2); err != nil {
@@ -2053,7 +2070,7 @@ func TestIncompleteChannelPolicies(t *testing.T) {
 	edgePolicy := newEdgePolicy(
 		chanID.ToUint64(), op, db, updateTime.Unix(),
 	)
-	edgePolicy.Flags = 0
+	edgePolicy.ChannelFlags = 0
 	edgePolicy.Node = node2
 	edgePolicy.SigBytes = testSig.Serialize()
 	if err := graph.UpdateEdgePolicy(edgePolicy); err != nil {
@@ -2068,7 +2085,7 @@ func TestIncompleteChannelPolicies(t *testing.T) {
 	edgePolicy = newEdgePolicy(
 		chanID.ToUint64(), op, db, updateTime.Unix(),
 	)
-	edgePolicy.Flags = 1
+	edgePolicy.ChannelFlags = 1
 	edgePolicy.Node = node1
 	edgePolicy.SigBytes = testSig.Serialize()
 	if err := graph.UpdateEdgePolicy(edgePolicy); err != nil {
@@ -2125,7 +2142,7 @@ func TestChannelEdgePruningUpdateIndexDeletion(t *testing.T) {
 	}
 
 	edge1 := randEdgePolicy(chanID.ToUint64(), edgeInfo.ChannelPoint, db)
-	edge1.Flags = 0
+	edge1.ChannelFlags = 0
 	edge1.Node = node1
 	edge1.SigBytes = testSig.Serialize()
 	if err := graph.UpdateEdgePolicy(edge1); err != nil {
@@ -2133,7 +2150,7 @@ func TestChannelEdgePruningUpdateIndexDeletion(t *testing.T) {
 	}
 
 	edge2 := randEdgePolicy(chanID.ToUint64(), edgeInfo.ChannelPoint, db)
-	edge2.Flags = 1
+	edge2.ChannelFlags = 1
 	edge2.Node = node2
 	edge2.SigBytes = testSig.Serialize()
 	if err := graph.UpdateEdgePolicy(edge2); err != nil {
@@ -2190,12 +2207,12 @@ func TestChannelEdgePruningUpdateIndexDeletion(t *testing.T) {
 
 	// Now, we'll update the edge policies to ensure the old timestamps are
 	// removed from the update index.
-	edge1.Flags = 2
+	edge1.ChannelFlags = 2
 	edge1.LastUpdate = time.Now()
 	if err := graph.UpdateEdgePolicy(edge1); err != nil {
 		t.Fatalf("unable to update edge: %v", err)
 	}
-	edge2.Flags = 3
+	edge2.ChannelFlags = 3
 	edge2.LastUpdate = edge1.LastUpdate.Add(time.Hour)
 	if err := graph.UpdateEdgePolicy(edge2); err != nil {
 		t.Fatalf("unable to update edge: %v", err)
@@ -2282,7 +2299,7 @@ func TestPruneGraphNodes(t *testing.T) {
 	// We'll now insert an advertised edge, but it'll only be the edge that
 	// points from the first to the second node.
 	edge1 := randEdgePolicy(chanID.ToUint64(), edgeInfo.ChannelPoint, db)
-	edge1.Flags = 0
+	edge1.ChannelFlags = 0
 	edge1.Node = node1
 	edge1.SigBytes = testSig.Serialize()
 	if err := graph.UpdateEdgePolicy(edge1); err != nil {
@@ -2594,6 +2611,173 @@ func TestNodeIsPublic(t *testing.T) {
 	)
 }
 
+// TestEdgePolicyMissingMaxHtcl tests that if we find a ChannelEdgePolicy in
+// the DB that indicates that it should support the htlc_maximum_value_msat
+// field, but it is not part of the opaque data, then we'll handle it as it is
+// unknown. It also checks that we are correctly able to overwrite it when we
+// receive the proper update.
+func TestEdgePolicyMissingMaxHtcl(t *testing.T) {
+	t.Parallel()
+
+	db, cleanUp, err := makeTestDB()
+	defer cleanUp()
+	if err != nil {
+		t.Fatalf("unable to make test database: %v", err)
+	}
+
+	graph := db.ChannelGraph()
+
+	// We'd like to test the update of edges inserted into the database, so
+	// we create two vertexes to connect.
+	node1, err := createTestVertex(db)
+	if err != nil {
+		t.Fatalf("unable to create test node: %v", err)
+	}
+	if err := graph.AddLightningNode(node1); err != nil {
+		t.Fatalf("unable to add node: %v", err)
+	}
+	node2, err := createTestVertex(db)
+	if err != nil {
+		t.Fatalf("unable to create test node: %v", err)
+	}
+
+	edgeInfo, edge1, edge2 := createChannelEdge(db, node1, node2)
+	if err := graph.AddLightningNode(node2); err != nil {
+		t.Fatalf("unable to add node: %v", err)
+	}
+	if err := graph.AddChannelEdge(edgeInfo); err != nil {
+		t.Fatalf("unable to create channel edge: %v", err)
+	}
+
+	chanID := edgeInfo.ChannelID
+	from := edge2.Node.PubKeyBytes[:]
+	to := edge1.Node.PubKeyBytes[:]
+
+	// We'll remove the no max_htlc field from the first edge policy, and
+	// all other opaque data, and serialize it.
+	edge1.MessageFlags = 0
+	edge1.ExtraOpaqueData = nil
+
+	var b bytes.Buffer
+	err = serializeChanEdgePolicy(&b, edge1, to)
+	if err != nil {
+		t.Fatalf("unable to serialize policy")
+	}
+
+	// Set the max_htlc field. The extra bytes added to the serialization
+	// will be the opaque data containing the serialized field.
+	edge1.MessageFlags = lnwire.ChanUpdateOptionMaxHtlc
+	edge1.MaxHTLC = 13928598
+	var b2 bytes.Buffer
+	err = serializeChanEdgePolicy(&b2, edge1, to)
+	if err != nil {
+		t.Fatalf("unable to serialize policy")
+	}
+
+	withMaxHtlc := b2.Bytes()
+
+	// Remove the opaque data from the serialization.
+	stripped := withMaxHtlc[:len(b.Bytes())]
+
+	// Attempting to deserialize these bytes should return an error.
+	r := bytes.NewReader(stripped)
+	err = db.View(func(tx *bbolt.Tx) error {
+		nodes := tx.Bucket(nodeBucket)
+		if nodes == nil {
+			return ErrGraphNotFound
+		}
+
+		_, err = deserializeChanEdgePolicy(r, nodes)
+		if err != ErrEdgePolicyOptionalFieldNotFound {
+			t.Fatalf("expected "+
+				"ErrEdgePolicyOptionalFieldNotFound, got %v",
+				err)
+		}
+
+		return nil
+	})
+	if err != nil {
+		t.Fatalf("error reading db: %v", err)
+	}
+
+	// Put the stripped bytes in the DB.
+	err = db.Update(func(tx *bbolt.Tx) error {
+		edges := tx.Bucket(edgeBucket)
+		if edges == nil {
+			return ErrEdgeNotFound
+		}
+
+		edgeIndex := edges.Bucket(edgeIndexBucket)
+		if edgeIndex == nil {
+			return ErrEdgeNotFound
+		}
+
+		var edgeKey [33 + 8]byte
+		copy(edgeKey[:], from)
+		byteOrder.PutUint64(edgeKey[33:], edge1.ChannelID)
+
+		var scratch [8]byte
+		var indexKey [8 + 8]byte
+		copy(indexKey[:], scratch[:])
+		byteOrder.PutUint64(indexKey[8:], edge1.ChannelID)
+
+		updateIndex, err := edges.CreateBucketIfNotExists(edgeUpdateIndexBucket)
+		if err != nil {
+			return err
+		}
+
+		if err := updateIndex.Put(indexKey[:], nil); err != nil {
+			return err
+		}
+
+		return edges.Put(edgeKey[:], stripped)
+	})
+	if err != nil {
+		t.Fatalf("error writing db: %v", err)
+	}
+
+	// And add the second, unmodified edge.
+	if err := graph.UpdateEdgePolicy(edge2); err != nil {
+		t.Fatalf("unable to update edge: %v", err)
+	}
+
+	// Attempt to fetch the edge and policies from the DB. Since the policy
+	// we added is invalid according to the new format, it should be as we
+	// are not aware of the policy (indicated by the policy returned being
+	// nil)
+	dbEdgeInfo, dbEdge1, dbEdge2, err := graph.FetchChannelEdgesByID(chanID)
+	if err != nil {
+		t.Fatalf("unable to fetch channel by ID: %v", err)
+	}
+
+	// The first edge should have a nil-policy returned
+	if dbEdge1 != nil {
+		t.Fatalf("expected db edge to be nil")
+	}
+	if err := compareEdgePolicies(dbEdge2, edge2); err != nil {
+		t.Fatalf("edge doesn't match: %v", err)
+	}
+	assertEdgeInfoEqual(t, dbEdgeInfo, edgeInfo)
+
+	// Now add the original, unmodified edge policy, and make sure the edge
+	// policies then become fully populated.
+	if err := graph.UpdateEdgePolicy(edge1); err != nil {
+		t.Fatalf("unable to update edge: %v", err)
+	}
+
+	dbEdgeInfo, dbEdge1, dbEdge2, err = graph.FetchChannelEdgesByID(chanID)
+	if err != nil {
+		t.Fatalf("unable to fetch channel by ID: %v", err)
+	}
+	if err := compareEdgePolicies(dbEdge1, edge1); err != nil {
+		t.Fatalf("edge doesn't match: %v", err)
+	}
+	if err := compareEdgePolicies(dbEdge2, edge2); err != nil {
+		t.Fatalf("edge doesn't match: %v", err)
+	}
+	assertEdgeInfoEqual(t, dbEdgeInfo, edgeInfo)
+}
+
 // compareNodes is used to compare two LightningNodes while excluding the
 // Features struct, which cannot be compared as the semantics for reserializing
 // the featuresMap have not been defined.
@@ -2645,9 +2829,13 @@ func compareEdgePolicies(a, b *ChannelEdgePolicy) error {
 		return fmt.Errorf("edge LastUpdate doesn't match: expected %#v, \n "+
 			"got %#v", a.LastUpdate, b.LastUpdate)
 	}
-	if a.Flags != b.Flags {
-		return fmt.Errorf("Flags doesn't match: expected %v, "+
-			"got %v", a.Flags, b.Flags)
+	if a.MessageFlags != b.MessageFlags {
+		return fmt.Errorf("MessageFlags doesn't match: expected %v, "+
+			"got %v", a.MessageFlags, b.MessageFlags)
+	}
+	if a.ChannelFlags != b.ChannelFlags {
+		return fmt.Errorf("ChannelFlags doesn't match: expected %v, "+
+			"got %v", a.ChannelFlags, b.ChannelFlags)
 	}
 	if a.TimeLockDelta != b.TimeLockDelta {
 		return fmt.Errorf("TimeLockDelta doesn't match: expected %v, "+
@@ -2657,6 +2845,10 @@ func compareEdgePolicies(a, b *ChannelEdgePolicy) error {
 		return fmt.Errorf("MinHTLC doesn't match: expected %v, "+
 			"got %v", a.MinHTLC, b.MinHTLC)
 	}
+	if a.MaxHTLC != b.MaxHTLC {
+		return fmt.Errorf("MaxHTLC doesn't match: expected %v, "+
+			"got %v", a.MaxHTLC, b.MaxHTLC)
+	}
 	if a.FeeBaseMSat != b.FeeBaseMSat {
 		return fmt.Errorf("FeeBaseMSat doesn't match: expected %v, "+
 			"got %v", a.FeeBaseMSat, b.FeeBaseMSat)

discovery/chan_series.go

@@ -327,9 +327,11 @@ func (c *ChanSeries) FetchChanUpdates(chain chainhash.Hash,
 			ChainHash:       chanInfo.ChainHash,
 			ShortChannelID:  shortChanID,
 			Timestamp:       uint32(e1.LastUpdate.Unix()),
-			Flags:           e1.Flags,
+			MessageFlags:    e1.MessageFlags,
+			ChannelFlags:    e1.ChannelFlags,
 			TimeLockDelta:   e1.TimeLockDelta,
 			HtlcMinimumMsat: e1.MinHTLC,
+			HtlcMaximumMsat: e1.MaxHTLC,
 			BaseFee:         uint32(e1.FeeBaseMSat),
 			FeeRate:         uint32(e1.FeeProportionalMillionths),
 			ExtraOpaqueData: e1.ExtraOpaqueData,
@@ -346,9 +348,11 @@ func (c *ChanSeries) FetchChanUpdates(chain chainhash.Hash,
 			ChainHash:       chanInfo.ChainHash,
 			ShortChannelID:  shortChanID,
 			Timestamp:       uint32(e2.LastUpdate.Unix()),
-			Flags:           e2.Flags,
+			MessageFlags:    e2.MessageFlags,
+			ChannelFlags:    e2.ChannelFlags,
 			TimeLockDelta:   e2.TimeLockDelta,
 			HtlcMinimumMsat: e2.MinHTLC,
+			HtlcMaximumMsat: e2.MaxHTLC,
 			BaseFee:         uint32(e2.FeeBaseMSat),
 			FeeRate:         uint32(e2.FeeProportionalMillionths),
 			ExtraOpaqueData: e2.ExtraOpaqueData,

discovery/gossiper.go

@@ -560,7 +560,7 @@ func (d *AuthenticatedGossiper) ProcessLocalAnnouncement(msg lnwire.Message,
 }
 
 // channelUpdateID is a unique identifier for ChannelUpdate messages, as
-// channel updates can be identified by the (ShortChannelID, Flags)
+// channel updates can be identified by the (ShortChannelID, ChannelFlags)
 // tuple.
 type channelUpdateID struct {
 	// channelID represents the set of data which is needed to
@@ -570,7 +570,7 @@ type channelUpdateID struct {
 	// Flags least-significant bit must be set to 0 if the creating node
 	// corresponds to the first node in the previously sent channel
 	// announcement and 1 otherwise.
-	flags lnwire.ChanUpdateFlag
+	flags lnwire.ChanUpdateChanFlags
 }
 
 // msgWithSenders is a wrapper struct around a message, and the set of peers
@@ -669,13 +669,13 @@ func (d *deDupedAnnouncements) addMsg(message networkMsg) {
 		mws.senders[sender] = struct{}{}
 		d.channelAnnouncements[deDupKey] = mws
 
-	// Channel updates are identified by the (short channel id, flags)
-	// tuple.
+	// Channel updates are identified by the (short channel id,
+	// channelflags) tuple.
 	case *lnwire.ChannelUpdate:
 		sender := routing.NewVertex(message.source)
 		deDupKey := channelUpdateID{
 			msg.ShortChannelID,
-			msg.Flags,
+			msg.ChannelFlags,
 		}
 
 		oldTimestamp := uint32(0)
@@ -1321,6 +1321,17 @@ func (d *AuthenticatedGossiper) retransmitStaleChannels() error {
 			return nil
 		}
 
+		// If this edge has a ChannelUpdate that was created before the
+		// introduction of the MaxHTLC field, then we'll update this
+		// edge to propagate this information in the network.
+		if !edge.MessageFlags.HasMaxHtlc() {
+			edgesToUpdate = append(edgesToUpdate, updateTuple{
+				info: info,
+				edge: edge,
+			})
+			return nil
+		}
+
 		const broadcastInterval = time.Hour * 24
 
 		timeElapsed := time.Since(edge.LastUpdate)
@@ -1911,7 +1922,7 @@ func (d *AuthenticatedGossiper) processNetworkAnnouncement(
 		// announcement for this edge.
 		timestamp := time.Unix(int64(msg.Timestamp), 0)
 		if d.cfg.Router.IsStaleEdgePolicy(
-			msg.ShortChannelID, timestamp, msg.Flags,
+			msg.ShortChannelID, timestamp, msg.ChannelFlags,
 		) {
 
 			nMsg.err <- nil
@@ -1986,16 +1997,17 @@ func (d *AuthenticatedGossiper) processNetworkAnnouncement(
 		// edge is being updated.
 		var pubKey *btcec.PublicKey
 		switch {
-		case msg.Flags&lnwire.ChanUpdateDirection == 0:
+		case msg.ChannelFlags&lnwire.ChanUpdateDirection == 0:
 			pubKey, _ = chanInfo.NodeKey1()
-		case msg.Flags&lnwire.ChanUpdateDirection == 1:
+		case msg.ChannelFlags&lnwire.ChanUpdateDirection == 1:
 			pubKey, _ = chanInfo.NodeKey2()
 		}
 
-		// Validate the channel announcement with the expected public
-		// key, In the case of an invalid channel , we'll return an
-		// error to the caller and exit early.
-		if err := routing.ValidateChannelUpdateAnn(pubKey, msg); err != nil {
+		// Validate the channel announcement with the expected public key and
+		// channel capacity. In the case of an invalid channel update, we'll
+		// return an error to the caller and exit early.
+		err = routing.ValidateChannelUpdateAnn(pubKey, chanInfo.Capacity, msg)
+		if err != nil {
 			rErr := fmt.Errorf("unable to validate channel "+
 				"update announcement for short_chan_id=%v: %v",
 				spew.Sdump(msg.ShortChannelID), err)
@@ -2009,9 +2021,11 @@ func (d *AuthenticatedGossiper) processNetworkAnnouncement(
 			SigBytes:                  msg.Signature.ToSignatureBytes(),
 			ChannelID:                 shortChanID,
 			LastUpdate:                timestamp,
-			Flags:                     msg.Flags,
+			MessageFlags:              msg.MessageFlags,
+			ChannelFlags:              msg.ChannelFlags,
 			TimeLockDelta:             msg.TimeLockDelta,
 			MinHTLC:                   msg.HtlcMinimumMsat,
+			MaxHTLC:                   msg.HtlcMaximumMsat,
 			FeeBaseMSat:               lnwire.MilliSatoshi(msg.BaseFee),
 			FeeProportionalMillionths: lnwire.MilliSatoshi(msg.FeeRate),
 			ExtraOpaqueData:           msg.ExtraOpaqueData,
@@ -2041,9 +2055,9 @@ func (d *AuthenticatedGossiper) processNetworkAnnouncement(
 			// Get our peer's public key.
 			var remotePub *btcec.PublicKey
 			switch {
-			case msg.Flags&lnwire.ChanUpdateDirection == 0:
+			case msg.ChannelFlags&lnwire.ChanUpdateDirection == 0:
 				remotePub, _ = chanInfo.NodeKey2()
-			case msg.Flags&lnwire.ChanUpdateDirection == 1:
+			case msg.ChannelFlags&lnwire.ChanUpdateDirection == 1:
 				remotePub, _ = chanInfo.NodeKey1()
 			}
 
@@ -2504,7 +2518,12 @@ func (d *AuthenticatedGossiper) updateChannel(info *channeldb.ChannelEdgeInfo,
 	edge *channeldb.ChannelEdgePolicy) (*lnwire.ChannelAnnouncement,
 	*lnwire.ChannelUpdate, error) {
 
-	var err error
+	// We'll make sure we support the new max_htlc field if not already
+	// present.
+	if !edge.MessageFlags.HasMaxHtlc() {
+		edge.MessageFlags |= lnwire.ChanUpdateOptionMaxHtlc
+		edge.MaxHTLC = lnwire.NewMSatFromSatoshis(info.Capacity)
+	}
 
 	// Make sure timestamp is always increased, such that our update gets
 	// propagated.
@@ -2513,17 +2532,22 @@ func (d *AuthenticatedGossiper) updateChannel(info *channeldb.ChannelEdgeInfo,
 		timestamp = edge.LastUpdate.Unix() + 1
 	}
 	edge.LastUpdate = time.Unix(timestamp, 0)
+
 	chanUpdate := &lnwire.ChannelUpdate{
 		ChainHash:       info.ChainHash,
 		ShortChannelID:  lnwire.NewShortChanIDFromInt(edge.ChannelID),
 		Timestamp:       uint32(timestamp),
-		Flags:           edge.Flags,
+		MessageFlags:    edge.MessageFlags,
+		ChannelFlags:    edge.ChannelFlags,
 		TimeLockDelta:   edge.TimeLockDelta,
 		HtlcMinimumMsat: edge.MinHTLC,
+		HtlcMaximumMsat: edge.MaxHTLC,
 		BaseFee:         uint32(edge.FeeBaseMSat),
 		FeeRate:         uint32(edge.FeeProportionalMillionths),
 		ExtraOpaqueData: edge.ExtraOpaqueData,
 	}
+
+	var err error
 	chanUpdate.Signature, err = lnwire.NewSigFromRawSignature(edge.SigBytes)
 	if err != nil {
 		return nil, nil, err
@@ -2546,7 +2570,7 @@ func (d *AuthenticatedGossiper) updateChannel(info *channeldb.ChannelEdgeInfo,
 
 	// To ensure that our signature is valid, we'll verify it ourself
 	// before committing it to the slice returned.
-	err = routing.ValidateChannelUpdateAnn(d.selfKey, chanUpdate)
+	err = routing.ValidateChannelUpdateAnn(d.selfKey, info.Capacity, chanUpdate)
 	if err != nil {
 		return nil, nil, fmt.Errorf("generated invalid channel "+
 			"update sig: %v", err)

discovery/gossiper_test.go

@@ -10,6 +10,7 @@ import (
 	"net"
 	"os"
 	"reflect"
+	"strings"
 	"sync"
 	"testing"
 	"time"
@@ -17,6 +18,7 @@ import (
 	"github.com/btcsuite/btcd/btcec"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
+	"github.com/btcsuite/btcutil"
 	"github.com/davecgh/go-spew/spew"
 	"github.com/go-errors/errors"
 	"github.com/lightningnetwork/lnd/chainntnfs"
@@ -54,9 +56,10 @@ var (
 	nodeKeyPriv2, _ = btcec.NewPrivateKey(btcec.S256())
 	nodeKeyPub2     = nodeKeyPriv2.PubKey()
 
-	trickleDelay     = time.Millisecond * 100
-	retransmitDelay  = time.Hour * 1
-	proofMatureDelta uint32
+	trickleDelay        = time.Millisecond * 100
+	retransmitDelay     = time.Hour * 1
+	proofMatureDelta    uint32
+	maxBtcFundingAmount = btcutil.Amount(1<<62) - 1
 )
 
 // makeTestDB creates a new instance of the ChannelDB for testing purposes. A
@@ -130,6 +133,10 @@ func (r *mockGraphSource) AddEdge(info *channeldb.ChannelEdgeInfo) error {
 	if _, ok := r.infos[info.ChannelID]; ok {
 		return errors.New("info already exist")
 	}
+
+	// Usually, the capacity is fetched in the router from the funding txout.
+	// Since the mockGraphSource can't access the txout, assign a default value.
+	info.Capacity = maxBtcFundingAmount
 	r.infos[info.ChannelID] = info
 	return nil
 }
@@ -258,7 +265,7 @@ func (r *mockGraphSource) IsKnownEdge(chanID lnwire.ShortChannelID) bool {
 // IsStaleEdgePolicy returns true if the graph source has a channel edge for
 // the passed channel ID (and flags) that have a more recent timestamp.
 func (r *mockGraphSource) IsStaleEdgePolicy(chanID lnwire.ShortChannelID,
-	timestamp time.Time, flags lnwire.ChanUpdateFlag) bool {
+	timestamp time.Time, flags lnwire.ChanUpdateChanFlags) bool {
 
 	edges, ok := r.edges[chanID.ToUint64()]
 	if !ok {
@@ -267,10 +274,10 @@ func (r *mockGraphSource) IsStaleEdgePolicy(chanID lnwire.ShortChannelID,
 
 	switch {
 
-	case len(edges) >= 1 && edges[0].Flags == flags:
+	case len(edges) >= 1 && edges[0].ChannelFlags == flags:
 		return !edges[0].LastUpdate.Before(timestamp)
 
-	case len(edges) >= 2 && edges[1].Flags == flags:
+	case len(edges) >= 2 && edges[1].ChannelFlags == flags:
 		return !edges[1].LastUpdate.Before(timestamp)
 
 	default:
@@ -440,20 +447,27 @@ func createNodeAnnouncement(priv *btcec.PrivateKey,
 	return a, nil
 }
 
-func createUpdateAnnouncement(blockHeight uint32, flags lnwire.ChanUpdateFlag,
+func createUpdateAnnouncement(blockHeight uint32,
+	flags lnwire.ChanUpdateChanFlags,
 	nodeKey *btcec.PrivateKey, timestamp uint32,
 	extraBytes ...[]byte) (*lnwire.ChannelUpdate, error) {
 
 	var err error
 
+	htlcMinMsat := lnwire.MilliSatoshi(prand.Int63())
 	a := &lnwire.ChannelUpdate{
 		ShortChannelID: lnwire.ShortChannelID{
 			BlockHeight: blockHeight,
 		},
 		Timestamp:       timestamp,
+		MessageFlags:    lnwire.ChanUpdateOptionMaxHtlc,
+		ChannelFlags:    flags,
 		TimeLockDelta:   uint16(prand.Int63()),
-		Flags:           flags,
-		HtlcMinimumMsat: lnwire.MilliSatoshi(prand.Int63()),
+		HtlcMinimumMsat: htlcMinMsat,
+
+		// Since the max HTLC must be greater than the min HTLC to pass channel
+		// update validation, set it to double the min htlc.
+		HtlcMaximumMsat: 2 * htlcMinMsat,
 		FeeRate:         uint32(prand.Int31()),
 		BaseFee:         uint32(prand.Int31()),
 	}
@@ -461,14 +475,7 @@ func createUpdateAnnouncement(blockHeight uint32, flags lnwire.ChanUpdateFlag,
 		a.ExtraOpaqueData = extraBytes[0]
 	}
 
-	pub := nodeKey.PubKey()
-	signer := mockSigner{nodeKey}
-	sig, err := SignAnnouncement(&signer, pub, a)
-	if err != nil {
-		return nil, err
-	}
-
-	a.Signature, err = lnwire.NewSigFromSignature(sig)
+	err = signUpdate(nodeKey, a)
 	if err != nil {
 		return nil, err
 	}
@@ -476,6 +483,22 @@ func createUpdateAnnouncement(blockHeight uint32, flags lnwire.ChanUpdateFlag,
 	return a, nil
 }
 
+func signUpdate(nodeKey *btcec.PrivateKey, a *lnwire.ChannelUpdate) error {
+	pub := nodeKey.PubKey()
+	signer := mockSigner{nodeKey}
+	sig, err := SignAnnouncement(&signer, pub, a)
+	if err != nil {
+		return err
+	}
+
+	a.Signature, err = lnwire.NewSigFromSignature(sig)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func createAnnouncementWithoutProof(blockHeight uint32,
 	extraBytes ...[]byte) *lnwire.ChannelAnnouncement {
 
@@ -2028,7 +2051,7 @@ func TestDeDuplicatedAnnouncements(t *testing.T) {
 	assertChannelUpdate := func(channelUpdate *lnwire.ChannelUpdate) {
 		channelKey := channelUpdateID{
 			ua3.ShortChannelID,
-			ua3.Flags,
+			ua3.ChannelFlags,
 		}
 
 		mws, ok := announcements.channelUpdates[channelKey]
@@ -2752,6 +2775,93 @@ func TestNodeAnnouncementNoChannels(t *testing.T) {
 	}
 }
 
+// TestOptionalFieldsChannelUpdateValidation tests that we're able to properly
+// validate the msg flags and optional max HTLC field of a ChannelUpdate.
+func TestOptionalFieldsChannelUpdateValidation(t *testing.T) {
+	t.Parallel()
+
+	ctx, cleanup, err := createTestCtx(0)
+	if err != nil {
+		t.Fatalf("can't create context: %v", err)
+	}
+	defer cleanup()
+
+	chanUpdateHeight := uint32(0)
+	timestamp := uint32(123456)
+	nodePeer := &mockPeer{nodeKeyPriv1.PubKey(), nil, nil}
+
+	// In this scenario, we'll test whether the message flags field in a channel
+	// update is properly handled.
+	chanAnn, err := createRemoteChannelAnnouncement(chanUpdateHeight)
+	if err != nil {
+		t.Fatalf("can't create channel announcement: %v", err)
+	}
+
+	select {
+	case err = <-ctx.gossiper.ProcessRemoteAnnouncement(chanAnn, nodePeer):
+	case <-time.After(2 * time.Second):
+		t.Fatal("did not process remote announcement")
+	}
+	if err != nil {
+		t.Fatalf("unable to process announcement: %v", err)
+	}
+
+	// The first update should fail from an invalid max HTLC field, which is
+	// less than the min HTLC.
+	chanUpdAnn, err := createUpdateAnnouncement(0, 0, nodeKeyPriv1, timestamp)
+	if err != nil {
+		t.Fatalf("unable to create channel update: %v", err)
+	}
+
+	chanUpdAnn.HtlcMinimumMsat = 5000
+	chanUpdAnn.HtlcMaximumMsat = 4000
+	if err := signUpdate(nodeKeyPriv1, chanUpdAnn); err != nil {
+		t.Fatalf("unable to sign channel update: %v", err)
+	}
+
+	select {
+	case err = <-ctx.gossiper.ProcessRemoteAnnouncement(chanUpdAnn, nodePeer):
+	case <-time.After(2 * time.Second):
+		t.Fatal("did not process remote announcement")
+	}
+	if err == nil || !strings.Contains(err.Error(), "invalid max htlc") {
+		t.Fatalf("expected chan update to error, instead got %v", err)
+	}
+
+	// The second update should fail because the message flag is set but
+	// the max HTLC field is 0.
+	chanUpdAnn.HtlcMinimumMsat = 0
+	chanUpdAnn.HtlcMaximumMsat = 0
+	if err := signUpdate(nodeKeyPriv1, chanUpdAnn); err != nil {
+		t.Fatalf("unable to sign channel update: %v", err)
+	}
+
+	select {
+	case err = <-ctx.gossiper.ProcessRemoteAnnouncement(chanUpdAnn, nodePeer):
+	case <-time.After(2 * time.Second):
+		t.Fatal("did not process remote announcement")
+	}
+	if err == nil || !strings.Contains(err.Error(), "invalid max htlc") {
+		t.Fatalf("expected chan update to error, instead got %v", err)
+	}
+
+	// The final update should succeed, since setting the flag 0 means the
+	// nonsense max_htlc field will just be ignored.
+	chanUpdAnn.MessageFlags = 0
+	if err := signUpdate(nodeKeyPriv1, chanUpdAnn); err != nil {
+		t.Fatalf("unable to sign channel update: %v", err)
+	}
+
+	select {
+	case err = <-ctx.gossiper.ProcessRemoteAnnouncement(chanUpdAnn, nodePeer):
+	case <-time.After(2 * time.Second):
+		t.Fatal("did not process remote announcement")
+	}
+	if err != nil {
+		t.Fatalf("unable to process announcement: %v", err)
+	}
+}
+
 // mockPeer implements the lnpeer.Peer interface and is used to test the
 // gossiper's interaction with peers.
 type mockPeer struct {

discovery/utils.go

@@ -72,9 +72,11 @@ func CreateChanAnnouncement(chanProof *channeldb.ChannelAuthProof,
 			ChainHash:       chanInfo.ChainHash,
 			ShortChannelID:  chanID,
 			Timestamp:       uint32(e1.LastUpdate.Unix()),
-			Flags:           e1.Flags,
+			MessageFlags:    e1.MessageFlags,
+			ChannelFlags:    e1.ChannelFlags,
 			TimeLockDelta:   e1.TimeLockDelta,
 			HtlcMinimumMsat: e1.MinHTLC,
+			HtlcMaximumMsat: e1.MaxHTLC,
 			BaseFee:         uint32(e1.FeeBaseMSat),
 			FeeRate:         uint32(e1.FeeProportionalMillionths),
 			ExtraOpaqueData: e1.ExtraOpaqueData,
@@ -89,9 +91,11 @@ func CreateChanAnnouncement(chanProof *channeldb.ChannelAuthProof,
 			ChainHash:       chanInfo.ChainHash,
 			ShortChannelID:  chanID,
 			Timestamp:       uint32(e2.LastUpdate.Unix()),
-			Flags:           e2.Flags,
+			MessageFlags:    e2.MessageFlags,
+			ChannelFlags:    e2.ChannelFlags,
 			TimeLockDelta:   e2.TimeLockDelta,
 			HtlcMinimumMsat: e2.MinHTLC,
+			HtlcMaximumMsat: e2.MaxHTLC,
 			BaseFee:         uint32(e2.FeeBaseMSat),
 			FeeRate:         uint32(e2.FeeProportionalMillionths),
 			ExtraOpaqueData: e2.ExtraOpaqueData,

fundingmanager.go

@@ -1090,7 +1090,7 @@ func (f *fundingManager) handleFundingOpen(fmsg *fundingOpenMsg) {
 		MaxAcceptedHtlcs: msg.MaxAcceptedHTLCs,
 		CsvDelay:         msg.CsvDelay,
 	}
-	err = reservation.CommitConstraints(channelConstraints)
+	err = reservation.CommitConstraints(channelConstraints, amt)
 	if err != nil {
 		fndgLog.Errorf("Unacceptable channel constraints: %v", err)
 		f.failFundingFlow(fmsg.peer, fmsg.msg.PendingChannelID, err)
@@ -1254,7 +1254,9 @@ func (f *fundingManager) handleFundingAccept(fmsg *fundingAcceptMsg) {
 		MaxAcceptedHtlcs: msg.MaxAcceptedHTLCs,
 		CsvDelay:         msg.CsvDelay,
 	}
-	err = resCtx.reservation.CommitConstraints(channelConstraints)
+	err = resCtx.reservation.CommitConstraints(
+		channelConstraints, resCtx.chanAmt,
+	)
 	if err != nil {
 		fndgLog.Warnf("Unacceptable channel constraints: %v", err)
 		f.failFundingFlow(fmsg.peer, fmsg.msg.PendingChannelID, err)
@@ -2109,11 +2111,18 @@ func (f *fundingManager) addToRouterGraph(completeChan *channeldb.OpenChannel,
 	// need to determine the smallest HTLC it deems economically relevant.
 	fwdMinHTLC := completeChan.LocalChanCfg.MinHTLC
 
+	// We'll obtain the max HTLC value we can forward in our direction, as
+	// we'll use this value within our ChannelUpdate. This value must be <=
+	// channel capacity and <= the maximum in-flight msats set by the peer, so
+	// we default to max in-flight msats as this value will always be <=
+	// channel capacity.
+	fwdMaxHTLC := completeChan.LocalChanCfg.MaxPendingAmount
+
 	ann, err := f.newChanAnnouncement(
 		f.cfg.IDKey, completeChan.IdentityPub,
 		completeChan.LocalChanCfg.MultiSigKey.PubKey,
 		completeChan.RemoteChanCfg.MultiSigKey.PubKey, *shortChanID,
-		chanID, fwdMinHTLC,
+		chanID, fwdMinHTLC, fwdMaxHTLC,
 	)
 	if err != nil {
 		return fmt.Errorf("error generating channel "+
@@ -2278,13 +2287,20 @@ func (f *fundingManager) annAfterSixConfs(completeChan *channeldb.OpenChannel,
 		// HTLC it deems economically relevant.
 		fwdMinHTLC := completeChan.LocalChanCfg.MinHTLC
 
+		// We'll obtain the max HTLC value we can forward in our direction, as
+		// we'll use this value within our ChannelUpdate. This value must be <=
+		// channel capacity and <= the maximum in-flight msats set by the peer,
+		// so we default to max in-flight msats as this value will always be <=
+		// channel capacity.
+		fwdMaxHTLC := completeChan.LocalChanCfg.MaxPendingAmount
+
 		// Create and broadcast the proofs required to make this channel
 		// public and usable for other nodes for routing.
 		err = f.announceChannel(
 			f.cfg.IDKey, completeChan.IdentityPub,
 			completeChan.LocalChanCfg.MultiSigKey.PubKey,
 			completeChan.RemoteChanCfg.MultiSigKey.PubKey,
-			*shortChanID, chanID, fwdMinHTLC,
+			*shortChanID, chanID, fwdMinHTLC, fwdMaxHTLC,
 		)
 		if err != nil {
 			return fmt.Errorf("channel announcement failed: %v", err)
@@ -2451,7 +2467,7 @@ type chanAnnouncement struct {
 func (f *fundingManager) newChanAnnouncement(localPubKey, remotePubKey,
 	localFundingKey, remoteFundingKey *btcec.PublicKey,
 	shortChanID lnwire.ShortChannelID, chanID lnwire.ChannelID,
-	fwdMinHTLC lnwire.MilliSatoshi) (*chanAnnouncement, error) {
+	fwdMinHTLC, fwdMaxHTLC lnwire.MilliSatoshi) (*chanAnnouncement, error) {
 
 	chainHash := *f.cfg.Wallet.Cfg.NetParams.GenesisHash
 
@@ -2468,7 +2484,7 @@ func (f *fundingManager) newChanAnnouncement(localPubKey, remotePubKey,
 	// being updated within the ChannelUpdateAnnouncement announcement
 	// below. A value of zero means it's the edge of the "first" node and 1
 	// being the other node.
-	var chanFlags lnwire.ChanUpdateFlag
+	var chanFlags lnwire.ChanUpdateChanFlags
 
 	// The lexicographical ordering of the two identity public keys of the
 	// nodes indicates which of the nodes is "first". If our serialized
@@ -2496,19 +2512,25 @@ func (f *fundingManager) newChanAnnouncement(localPubKey, remotePubKey,
 		chanFlags = 1
 	}
 
+	// Our channel update message flags will signal that we support the
+	// max_htlc field.
+	msgFlags := lnwire.ChanUpdateOptionMaxHtlc
+
 	// We announce the channel with the default values. Some of
 	// these values can later be changed by crafting a new ChannelUpdate.
 	chanUpdateAnn := &lnwire.ChannelUpdate{
 		ShortChannelID: shortChanID,
 		ChainHash:      chainHash,
 		Timestamp:      uint32(time.Now().Unix()),
-		Flags:          chanFlags,
+		MessageFlags:   msgFlags,
+		ChannelFlags:   chanFlags,
 		TimeLockDelta:  uint16(f.cfg.DefaultRoutingPolicy.TimeLockDelta),
 
 		// We use the HtlcMinimumMsat that the remote party required us
 		// to use, as our ChannelUpdate will be used to carry HTLCs
 		// towards them.
 		HtlcMinimumMsat: fwdMinHTLC,
+		HtlcMaximumMsat: fwdMaxHTLC,
 
 		BaseFee: uint32(f.cfg.DefaultRoutingPolicy.BaseFee),
 		FeeRate: uint32(f.cfg.DefaultRoutingPolicy.FeeRate),
@@ -2587,7 +2609,7 @@ func (f *fundingManager) newChanAnnouncement(localPubKey, remotePubKey,
 // finish, either successfully or with an error.
 func (f *fundingManager) announceChannel(localIDKey, remoteIDKey, localFundingKey,
 	remoteFundingKey *btcec.PublicKey, shortChanID lnwire.ShortChannelID,
-	chanID lnwire.ChannelID, fwdMinHTLC lnwire.MilliSatoshi) error {
+	chanID lnwire.ChannelID, fwdMinHTLC, fwdMaxHTLC lnwire.MilliSatoshi) error {
 
 	// First, we'll create the batch of announcements to be sent upon
 	// initial channel creation. This includes the channel announcement
@@ -2595,7 +2617,7 @@ func (f *fundingManager) announceChannel(localIDKey, remoteIDKey, localFundingKe
 	// proof needed to fully authenticate the channel.
 	ann, err := f.newChanAnnouncement(localIDKey, remoteIDKey,
 		localFundingKey, remoteFundingKey, shortChanID, chanID,
-		fwdMinHTLC,
+		fwdMinHTLC, fwdMaxHTLC,
 	)
 	if err != nil {
 		fndgLog.Errorf("can't generate channel announcement: %v", err)

fundingmanager_test.go

@@ -433,6 +433,7 @@ func recreateAliceFundingManager(t *testing.T, alice *testNode) {
 			FeeRate:       1000,
 			TimeLockDelta: 10,
 		},
+		RequiredRemoteMaxValue: oldCfg.RequiredRemoteMaxValue,
 		PublishTransaction: func(txn *wire.MsgTx) error {
 			publishChan <- txn
 			return nil
@@ -819,7 +820,8 @@ func assertAddedToRouterGraph(t *testing.T, alice, bob *testNode,
 // advertised value will be checked against the other node's default min_htlc
 // value.
 func assertChannelAnnouncements(t *testing.T, alice, bob *testNode,
-	customMinHtlc ...lnwire.MilliSatoshi) {
+	capacity btcutil.Amount, customMinHtlc ...lnwire.MilliSatoshi) {
+	t.Helper()
 
 	// After the FundingLocked message is sent, Alice and Bob will each
 	// send the following messages to their gossiper:
@@ -871,6 +873,24 @@ func assertChannelAnnouncements(t *testing.T, alice, bob *testNode,
 						minHtlc, m.HtlcMinimumMsat)
 				}
 
+				// The MaxHTLC value should at this point
+				// _always_ be the same as the
+				// maxValueInFlight capacity.
+				if m.MessageFlags != 1 {
+					t.Fatalf("expected message flags to "+
+						"be 1, was %v", m.MessageFlags)
+				}
+
+				maxPendingMsat := alice.fundingMgr.cfg.RequiredRemoteMaxValue(
+					capacity,
+				)
+				if maxPendingMsat != m.HtlcMaximumMsat {
+					t.Fatalf("expected ChannelUpdate to "+
+						"advertise max HTLC %v, had %v",
+						maxPendingMsat,
+						m.HtlcMaximumMsat)
+				}
+
 				gotChannelUpdate = true
 			}
 		}
@@ -1005,8 +1025,11 @@ func TestFundingManagerNormalWorkflow(t *testing.T) {
 
 	// Run through the process of opening the channel, up until the funding
 	// transaction is broadcasted.
-	fundingOutPoint := openChannel(t, alice, bob, 500000, 0, 1, updateChan,
-		true)
+	localAmt := btcutil.Amount(500000)
+	pushAmt := btcutil.Amount(0)
+	capacity := localAmt + pushAmt
+	fundingOutPoint := openChannel(t, alice, bob, localAmt, pushAmt, 1,
+		updateChan, true)
 
 	// Check that neither Alice nor Bob sent an error message.
 	assertErrorNotSent(t, alice.msgChan)
@@ -1037,7 +1060,7 @@ func TestFundingManagerNormalWorkflow(t *testing.T) {
 
 	// Make sure both fundingManagers send the expected channel
 	// announcements.
-	assertChannelAnnouncements(t, alice, bob)
+	assertChannelAnnouncements(t, alice, bob, capacity)
 
 	// Check that the state machine is updated accordingly
 	assertAddedToRouterGraph(t, alice, bob, fundingOutPoint)
@@ -1072,9 +1095,12 @@ func TestFundingManagerRestartBehavior(t *testing.T) {
 
 	// Run through the process of opening the channel, up until the funding
 	// transaction is broadcasted.
+	localAmt := btcutil.Amount(500000)
+	pushAmt := btcutil.Amount(0)
+	capacity := localAmt + pushAmt
 	updateChan := make(chan *lnrpc.OpenStatusUpdate)
-	fundingOutPoint := openChannel(t, alice, bob, 500000, 0, 1, updateChan,
-		true)
+	fundingOutPoint := openChannel(t, alice, bob, localAmt, pushAmt, 1,
+		updateChan, true)
 
 	// After the funding transaction gets mined, both nodes will send the
 	// fundingLocked message to the other peer. If the funding node fails
@@ -1175,7 +1201,7 @@ func TestFundingManagerRestartBehavior(t *testing.T) {
 
 	// Make sure both fundingManagers send the expected channel
 	// announcements.
-	assertChannelAnnouncements(t, alice, bob)
+	assertChannelAnnouncements(t, alice, bob, capacity)
 
 	// Check that the state machine is updated accordingly
 	assertAddedToRouterGraph(t, alice, bob, fundingOutPoint)
@@ -1207,9 +1233,12 @@ func TestFundingManagerOfflinePeer(t *testing.T) {
 
 	// Run through the process of opening the channel, up until the funding
 	// transaction is broadcasted.
+	localAmt := btcutil.Amount(500000)
+	pushAmt := btcutil.Amount(0)
+	capacity := localAmt + pushAmt
 	updateChan := make(chan *lnrpc.OpenStatusUpdate)
-	fundingOutPoint := openChannel(t, alice, bob, 500000, 0, 1, updateChan,
-		true)
+	fundingOutPoint := openChannel(t, alice, bob, localAmt, pushAmt, 1,
+		updateChan, true)
 
 	// After the funding transaction gets mined, both nodes will send the
 	// fundingLocked message to the other peer. If the funding node fails
@@ -1299,7 +1328,7 @@ func TestFundingManagerOfflinePeer(t *testing.T) {
 
 	// Make sure both fundingManagers send the expected channel
 	// announcements.
-	assertChannelAnnouncements(t, alice, bob)
+	assertChannelAnnouncements(t, alice, bob, capacity)
 
 	// Check that the state machine is updated accordingly
 	assertAddedToRouterGraph(t, alice, bob, fundingOutPoint)
@@ -1656,8 +1685,11 @@ func TestFundingManagerReceiveFundingLockedTwice(t *testing.T) {
 
 	// Run through the process of opening the channel, up until the funding
 	// transaction is broadcasted.
-	fundingOutPoint := openChannel(t, alice, bob, 500000, 0, 1, updateChan,
-		true)
+	localAmt := btcutil.Amount(500000)
+	pushAmt := btcutil.Amount(0)
+	capacity := localAmt + pushAmt
+	fundingOutPoint := openChannel(t, alice, bob, localAmt, pushAmt, 1,
+		updateChan, true)
 
 	// Notify that transaction was mined
 	alice.mockNotifier.oneConfChannel <- &chainntnfs.TxConfirmation{}
@@ -1684,7 +1716,7 @@ func TestFundingManagerReceiveFundingLockedTwice(t *testing.T) {
 
 	// Make sure both fundingManagers send the expected channel
 	// announcements.
-	assertChannelAnnouncements(t, alice, bob)
+	assertChannelAnnouncements(t, alice, bob, capacity)
 
 	// Check that the state machine is updated accordingly
 	assertAddedToRouterGraph(t, alice, bob, fundingOutPoint)
@@ -1745,8 +1777,11 @@ func TestFundingManagerRestartAfterChanAnn(t *testing.T) {
 
 	// Run through the process of opening the channel, up until the funding
 	// transaction is broadcasted.
-	fundingOutPoint := openChannel(t, alice, bob, 500000, 0, 1, updateChan,
-		true)
+	localAmt := btcutil.Amount(500000)
+	pushAmt := btcutil.Amount(0)
+	capacity := localAmt + pushAmt
+	fundingOutPoint := openChannel(t, alice, bob, localAmt, pushAmt, 1,
+		updateChan, true)
 
 	// Notify that transaction was mined
 	alice.mockNotifier.oneConfChannel <- &chainntnfs.TxConfirmation{}
@@ -1773,7 +1808,7 @@ func TestFundingManagerRestartAfterChanAnn(t *testing.T) {
 
 	// Make sure both fundingManagers send the expected channel
 	// announcements.
-	assertChannelAnnouncements(t, alice, bob)
+	assertChannelAnnouncements(t, alice, bob, capacity)
 
 	// Check that the state machine is updated accordingly
 	assertAddedToRouterGraph(t, alice, bob, fundingOutPoint)
@@ -1819,8 +1854,11 @@ func TestFundingManagerRestartAfterReceivingFundingLocked(t *testing.T) {
 
 	// Run through the process of opening the channel, up until the funding
 	// transaction is broadcasted.
-	fundingOutPoint := openChannel(t, alice, bob, 500000, 0, 1, updateChan,
-		true)
+	localAmt := btcutil.Amount(500000)
+	pushAmt := btcutil.Amount(0)
+	capacity := localAmt + pushAmt
+	fundingOutPoint := openChannel(t, alice, bob, localAmt, pushAmt, 1,
+		updateChan, true)
 
 	// Notify that transaction was mined
 	alice.mockNotifier.oneConfChannel <- &chainntnfs.TxConfirmation{}
@@ -1860,7 +1898,7 @@ func TestFundingManagerRestartAfterReceivingFundingLocked(t *testing.T) {
 
 	// Make sure both fundingManagers send the expected channel
 	// announcements.
-	assertChannelAnnouncements(t, alice, bob)
+	assertChannelAnnouncements(t, alice, bob, capacity)
 
 	// Check that the state machine is updated accordingly
 	assertAddedToRouterGraph(t, alice, bob, fundingOutPoint)
@@ -1889,8 +1927,11 @@ func TestFundingManagerPrivateChannel(t *testing.T) {
 
 	// Run through the process of opening the channel, up until the funding
 	// transaction is broadcasted.
-	fundingOutPoint := openChannel(t, alice, bob, 500000, 0, 1, updateChan,
-		false)
+	localAmt := btcutil.Amount(500000)
+	pushAmt := btcutil.Amount(0)
+	capacity := localAmt + pushAmt
+	fundingOutPoint := openChannel(t, alice, bob, localAmt, pushAmt, 1,
+		updateChan, false)
 
 	// Notify that transaction was mined
 	alice.mockNotifier.oneConfChannel <- &chainntnfs.TxConfirmation{}
@@ -1917,7 +1958,7 @@ func TestFundingManagerPrivateChannel(t *testing.T) {
 
 	// Make sure both fundingManagers send the expected channel
 	// announcements.
-	assertChannelAnnouncements(t, alice, bob)
+	assertChannelAnnouncements(t, alice, bob, capacity)
 
 	// The funding transaction is now confirmed, wait for the
 	// OpenStatusUpdate_ChanOpen update
@@ -1988,8 +2029,11 @@ func TestFundingManagerPrivateRestart(t *testing.T) {
 
 	// Run through the process of opening the channel, up until the funding
 	// transaction is broadcasted.
-	fundingOutPoint := openChannel(t, alice, bob, 500000, 0, 1, updateChan,
-		false)
+	localAmt := btcutil.Amount(500000)
+	pushAmt := btcutil.Amount(0)
+	capacity := localAmt + pushAmt
+	fundingOutPoint := openChannel(t, alice, bob, localAmt, pushAmt, 1,
+		updateChan, false)
 
 	// Notify that transaction was mined
 	alice.mockNotifier.oneConfChannel <- &chainntnfs.TxConfirmation{}
@@ -2016,7 +2060,7 @@ func TestFundingManagerPrivateRestart(t *testing.T) {
 
 	// Make sure both fundingManagers send the expected channel
 	// announcements.
-	assertChannelAnnouncements(t, alice, bob)
+	assertChannelAnnouncements(t, alice, bob, capacity)
 
 	// Note: We don't check for the addedToRouterGraph state because in
 	// the private channel mode, the state is quickly changed from
@@ -2110,14 +2154,18 @@ func TestFundingManagerCustomChannelParameters(t *testing.T) {
 	// needed.
 	updateChan := make(chan *lnrpc.OpenStatusUpdate)
 
+	localAmt := btcutil.Amount(5000000)
+	pushAmt := btcutil.Amount(0)
+	capacity := localAmt + pushAmt
+
 	// Create a funding request with the custom parameters and start the
 	// workflow.
 	errChan := make(chan error, 1)
 	initReq := &openChanReq{
 		targetPubkey:    bob.privKey.PubKey(),
 		chainHash:       *activeNetParams.GenesisHash,
-		localFundingAmt: 5000000,
-		pushAmt:         lnwire.NewMSatFromSatoshis(0),
+		localFundingAmt: localAmt,
+		pushAmt:         lnwire.NewMSatFromSatoshis(pushAmt),
 		private:         false,
 		minHtlc:         minHtlc,
 		remoteCsvDelay:  csvDelay,
@@ -2313,7 +2361,7 @@ func TestFundingManagerCustomChannelParameters(t *testing.T) {
 	// announcements. Alice should advertise the default MinHTLC value of
 	// 5, while bob should advertise the value minHtlc, since Alice
 	// required him to use it.
-	assertChannelAnnouncements(t, alice, bob, 5, minHtlc)
+	assertChannelAnnouncements(t, alice, bob, capacity, 5, minHtlc)
 
 	// The funding transaction is now confirmed, wait for the
 	// OpenStatusUpdate_ChanOpen update
@@ -2609,3 +2657,69 @@ func TestFundingManagerMaxConfs(t *testing.T) {
 			string(err.Data))
 	}
 }
+
+// TestFundingManagerRejectInvalidMaxValueInFlight makes sure that the funding
+// manager will act accordingly when the remote is requiring us to use a
+// max_value_in_flight larger than the channel capacity.
+func TestFundingManagerRejectInvalidMaxValueInFlight(t *testing.T) {
+	alice, bob := setupFundingManagers(t, defaultMaxPendingChannels)
+	defer tearDownFundingManagers(t, alice, bob)
+
+	localAmt := btcutil.Amount(500000)
+	pushAmt := btcutil.Amount(0)
+	capacity := localAmt + pushAmt
+
+	// Make Alice require a max_htlc_value_in_flight greater than the
+	// channel capacity.
+	alice.fundingMgr.cfg.RequiredRemoteMaxValue = func(
+		_ btcutil.Amount) lnwire.MilliSatoshi {
+		return lnwire.NewMSatFromSatoshis(capacity) + 100
+	}
+
+	// Create a funding request and start the workflow.
+	updateChan := make(chan *lnrpc.OpenStatusUpdate)
+	errChan := make(chan error, 1)
+	initReq := &openChanReq{
+		targetPubkey:    bob.privKey.PubKey(),
+		chainHash:       *activeNetParams.GenesisHash,
+		localFundingAmt: 500000,
+		pushAmt:         lnwire.NewMSatFromSatoshis(10),
+		private:         true,
+		updates:         updateChan,
+		err:             errChan,
+	}
+
+	alice.fundingMgr.initFundingWorkflow(bob, initReq)
+
+	// Alice should have sent the OpenChannel message to Bob.
+	var aliceMsg lnwire.Message
+	select {
+	case aliceMsg = <-alice.msgChan:
+	case err := <-initReq.err:
+		t.Fatalf("error init funding workflow: %v", err)
+	case <-time.After(time.Second * 5):
+		t.Fatalf("alice did not send OpenChannel message")
+	}
+
+	openChannelReq, ok := aliceMsg.(*lnwire.OpenChannel)
+	if !ok {
+		errorMsg, gotError := aliceMsg.(*lnwire.Error)
+		if gotError {
+			t.Fatalf("expected OpenChannel to be sent "+
+				"from bob, instead got error: %v",
+				lnwire.ErrorCode(errorMsg.Data[0]))
+		}
+		t.Fatalf("expected OpenChannel to be sent from "+
+			"alice, instead got %T", aliceMsg)
+	}
+
+	// Let Bob handle the init message.
+	bob.fundingMgr.processFundingOpen(openChannelReq, alice)
+
+	// Assert Bob responded with an ErrMaxValueInFlightTooLarge error.
+	err := assertFundingMsgSent(t, bob.msgChan, "Error").(*lnwire.Error)
+	if !strings.Contains(string(err.Data), "maxValueInFlight too large") {
+		t.Fatalf("expected ErrMaxValueInFlightTooLarge error, "+
+			"got \"%v\"", string(err.Data))
+	}
+}

lnwallet/errors.go

@@ -132,6 +132,16 @@ func ErrNumConfsTooLarge(numConfs, maxNumConfs uint32) error {
 	}
 }
 
+// ErrMaxValueInFlightTooLarge returns an error indicating that the 'max HTLC
+// value in flight' the remote required is too large to be accepted.
+func ErrMaxValueInFlightTooLarge(maxValInFlight,
+	maxMaxValInFlight lnwire.MilliSatoshi) ReservationError {
+	return ReservationError{
+		fmt.Errorf("maxValueInFlight too large: %v, max is %v",
+			maxValInFlight, maxMaxValInFlight),
+	}
+}
+
 // ErrChanTooSmall returns an error indicating that an incoming channel request
 // was too small. We'll reject any incoming channels if they're below our
 // configured value for the min channel size we'll accept.

lnwallet/interface_test.go

@@ -437,7 +437,9 @@ func testDualFundingReservationWorkflow(miner *rpctest.Harness,
 		MaxAcceptedHtlcs: lnwallet.MaxHTLCNumber / 2,
 		CsvDelay:         csvDelay,
 	}
-	err = aliceChanReservation.CommitConstraints(channelConstraints)
+	err = aliceChanReservation.CommitConstraints(
+		channelConstraints, fundingAmount*2,
+	)
 	if err != nil {
 		t.Fatalf("unable to verify constraints: %v", err)
 	}
@@ -471,7 +473,9 @@ func testDualFundingReservationWorkflow(miner *rpctest.Harness,
 	if err != nil {
 		t.Fatalf("bob unable to init channel reservation: %v", err)
 	}
-	err = bobChanReservation.CommitConstraints(channelConstraints)
+	err = bobChanReservation.CommitConstraints(
+		channelConstraints, fundingAmount*2,
+	)
 	if err != nil {
 		t.Fatalf("unable to verify constraints: %v", err)
 	}
@@ -869,7 +873,9 @@ func testSingleFunderReservationWorkflow(miner *rpctest.Harness,
 		MaxAcceptedHtlcs: lnwallet.MaxHTLCNumber / 2,
 		CsvDelay:         csvDelay,
 	}
-	err = aliceChanReservation.CommitConstraints(channelConstraints)
+	err = aliceChanReservation.CommitConstraints(
+		channelConstraints, fundingAmt,
+	)
 	if err != nil {
 		t.Fatalf("unable to verify constraints: %v", err)
 	}
@@ -903,7 +909,9 @@ func testSingleFunderReservationWorkflow(miner *rpctest.Harness,
 	if err != nil {
 		t.Fatalf("unable to create bob reservation: %v", err)
 	}
-	err = bobChanReservation.CommitConstraints(channelConstraints)
+	err = bobChanReservation.CommitConstraints(
+		channelConstraints, fundingAmt,
+	)
 	if err != nil {
 		t.Fatalf("unable to verify constraints: %v", err)
 	}

lnwallet/reservation.go

@@ -286,7 +286,9 @@ func (r *ChannelReservation) SetNumConfsRequired(numConfs uint16) {
 // of satoshis that can be transferred in a single commitment. This function
 // will also attempt to verify the constraints for sanity, returning an error
 // if the parameters are seemed unsound.
-func (r *ChannelReservation) CommitConstraints(c *channeldb.ChannelConstraints) error {
+func (r *ChannelReservation) CommitConstraints(c *channeldb.ChannelConstraints,
+	capacity btcutil.Amount) error {
+
 	r.Lock()
 	defer r.Unlock()
 
@@ -341,7 +343,15 @@ func (r *ChannelReservation) CommitConstraints(c *channeldb.ChannelConstraints)
 		)
 	}
 
-	// Our dust limit should always be less than or equal to our proposed
+	// Fail if the maxValueInFlight is greater than the channel capacity.
+	capacityMsat := lnwire.NewMSatFromSatoshis(capacity)
+	if c.MaxPendingAmount > capacityMsat {
+		return ErrMaxValueInFlightTooLarge(
+			c.MaxPendingAmount, capacityMsat,
+		)
+	}
+
+	// Our dust limit should always be less than or equal our proposed
 	// channel reserve.
 	if r.ourContribution.DustLimit > c.ChanReserve {
 		r.ourContribution.DustLimit = c.ChanReserve

lnwire/channel_update.go

@@ -2,22 +2,44 @@ package lnwire
 
 import (
 	"bytes"
+	"fmt"
 	"io"
 	"io/ioutil"
 
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 )
 
-// ChanUpdateFlag is a bitfield that signals various options concerning a
+// ChanUpdateMsgFlags is a bitfield that signals whether optional fields are
+// present in the ChannelUpdate.
+type ChanUpdateMsgFlags uint8
+
+const (
+	// ChanUpdateOptionMaxHtlc is a bit that indicates whether the
+	// optional htlc_maximum_msat field is present in this ChannelUpdate.
+	ChanUpdateOptionMaxHtlc ChanUpdateMsgFlags = 1 << iota
+)
+
+// String returns the bitfield flags as a string.
+func (c ChanUpdateMsgFlags) String() string {
+	return fmt.Sprintf("%08b", c)
+}
+
+// HasMaxHtlc returns true if the htlc_maximum_msat option bit is set in the
+// message flags.
+func (c ChanUpdateMsgFlags) HasMaxHtlc() bool {
+	return c&ChanUpdateOptionMaxHtlc != 0
+}
+
+// ChanUpdateChanFlags is a bitfield that signals various options concerning a
 // particular channel edge. Each bit is to be examined in order to determine
 // how the ChannelUpdate message is to be interpreted.
-type ChanUpdateFlag uint16
+type ChanUpdateChanFlags uint8
 
 const (
 	// ChanUpdateDirection indicates the direction of a channel update. If
 	// this bit is set to 0 if Node1 (the node with the "smaller" Node ID)
 	// is updating the channel, and to 1 otherwise.
-	ChanUpdateDirection ChanUpdateFlag = 1 << iota
+	ChanUpdateDirection ChanUpdateChanFlags = 1 << iota
 
 	// ChanUpdateDisabled is a bit that indicates if the channel edge
 	// selected by the ChanUpdateDirection bit is to be treated as being
@@ -25,6 +47,11 @@ const (
 	ChanUpdateDisabled
 )
 
+// String returns the bitfield flags as a string.
+func (c ChanUpdateChanFlags) String() string {
+	return fmt.Sprintf("%08b", c)
+}
+
 // ChannelUpdate message is used after channel has been initially announced.
 // Each side independently announces its fees and minimum expiry for HTLCs and
 // other parameters. Also this message is used to redeclare initially set
@@ -48,13 +75,18 @@ type ChannelUpdate struct {
 	// the last-received.
 	Timestamp uint32
 
-	// Flags is a bitfield that describes additional meta-data concerning
-	// how the update is to be interpreted. Currently, the
+	// MessageFlags is a bitfield that describes whether optional fields
+	// are present in this update. Currently, the least-significant bit
+	// must be set to 1 if the optional field MaxHtlc is present.
+	MessageFlags ChanUpdateMsgFlags
+
+	// ChannelFlags is a bitfield that describes additional meta-data
+	// concerning how the update is to be interpreted. Currently, the
 	// least-significant bit must be set to 0 if the creating node
 	// corresponds to the first node in the previously sent channel
 	// announcement and 1 otherwise. If the second bit is set, then the
 	// channel is set to be disabled.
-	Flags ChanUpdateFlag
+	ChannelFlags ChanUpdateChanFlags
 
 	// TimeLockDelta is the minimum number of blocks this node requires to
 	// be added to the expiry of HTLCs. This is a security parameter
@@ -75,6 +107,9 @@ type ChannelUpdate struct {
 	// satoshi.
 	FeeRate uint32
 
+	// HtlcMaximumMsat is the maximum HTLC value which will be accepted.
+	HtlcMaximumMsat MilliSatoshi
+
 	// ExtraOpaqueData is the set of data that was appended to this
 	// message, some of which we may not actually know how to iterate or
 	// parse. By holding onto this data, we ensure that we're able to
@@ -98,7 +133,8 @@ func (a *ChannelUpdate) Decode(r io.Reader, pver uint32) error {
 		a.ChainHash[:],
 		&a.ShortChannelID,
 		&a.Timestamp,
-		&a.Flags,
+		&a.MessageFlags,
+		&a.ChannelFlags,
 		&a.TimeLockDelta,
 		&a.HtlcMinimumMsat,
 		&a.BaseFee,
@@ -108,6 +144,13 @@ func (a *ChannelUpdate) Decode(r io.Reader, pver uint32) error {
 		return err
 	}
 
+	// Now check whether the max HTLC field is present and read it if so.
+	if a.MessageFlags.HasMaxHtlc() {
+		if err := ReadElements(r, &a.HtlcMaximumMsat); err != nil {
+			return err
+		}
+	}
+
 	// Now that we've read out all the fields that we explicitly know of,
 	// we'll collect the remainder into the ExtraOpaqueData field. If there
 	// aren't any bytes, then we'll snip off the slice to avoid carrying
@@ -128,18 +171,32 @@ func (a *ChannelUpdate) Decode(r io.Reader, pver uint32) error {
 //
 // This is part of the lnwire.Message interface.
 func (a *ChannelUpdate) Encode(w io.Writer, pver uint32) error {
-	return WriteElements(w,
+	err := WriteElements(w,
 		a.Signature,
 		a.ChainHash[:],
 		a.ShortChannelID,
 		a.Timestamp,
-		a.Flags,
+		a.MessageFlags,
+		a.ChannelFlags,
 		a.TimeLockDelta,
 		a.HtlcMinimumMsat,
 		a.BaseFee,
 		a.FeeRate,
-		a.ExtraOpaqueData,
 	)
+	if err != nil {
+		return err
+	}
+
+	// Now append optional fields if they are set. Currently, the only
+	// optional field is max HTLC.
+	if a.MessageFlags.HasMaxHtlc() {
+		if err := WriteElements(w, a.HtlcMaximumMsat); err != nil {
+			return err
+		}
+	}
+
+	// Finally, append any extra opaque data.
+	return WriteElements(w, a.ExtraOpaqueData)
 }
 
 // MsgType returns the integer uniquely identifying this message type on the
@@ -168,16 +225,29 @@ func (a *ChannelUpdate) DataToSign() ([]byte, error) {
 		a.ChainHash[:],
 		a.ShortChannelID,
 		a.Timestamp,
-		a.Flags,
+		a.MessageFlags,
+		a.ChannelFlags,
 		a.TimeLockDelta,
 		a.HtlcMinimumMsat,
 		a.BaseFee,
 		a.FeeRate,
-		a.ExtraOpaqueData,
 	)
 	if err != nil {
 		return nil, err
 	}
 
+	// Now append optional fields if they are set. Currently, the only
+	// optional field is max HTLC.
+	if a.MessageFlags.HasMaxHtlc() {
+		if err := WriteElements(&w, a.HtlcMaximumMsat); err != nil {
+			return nil, err
+		}
+	}
+
+	// Finally, append any extra opaque data.
+	if err := WriteElements(&w, a.ExtraOpaqueData); err != nil {
+		return nil, err
+	}
+
 	return w.Bytes(), nil
 }

lnwire/lnwire.go

@@ -105,9 +105,15 @@ func WriteElement(w io.Writer, element interface{}) error {
 		if _, err := w.Write(b[:]); err != nil {
 			return err
 		}
-	case ChanUpdateFlag:
-		var b [2]byte
-		binary.BigEndian.PutUint16(b[:], uint16(e))
+	case ChanUpdateMsgFlags:
+		var b [1]byte
+		b[0] = uint8(e)
+		if _, err := w.Write(b[:]); err != nil {
+			return err
+		}
+	case ChanUpdateChanFlags:
+		var b [1]byte
+		b[0] = uint8(e)
 		if _, err := w.Write(b[:]); err != nil {
 			return err
 		}
@@ -470,12 +476,18 @@ func ReadElement(r io.Reader, element interface{}) error {
 			return err
 		}
 		*e = binary.BigEndian.Uint16(b[:])
-	case *ChanUpdateFlag:
-		var b [2]byte
-		if _, err := io.ReadFull(r, b[:]); err != nil {
+	case *ChanUpdateMsgFlags:
+		var b [1]uint8
+		if _, err := r.Read(b[:]); err != nil {
 			return err
 		}
-		*e = ChanUpdateFlag(binary.BigEndian.Uint16(b[:]))
+		*e = ChanUpdateMsgFlags(b[0])
+	case *ChanUpdateChanFlags:
+		var b [1]uint8
+		if _, err := r.Read(b[:]); err != nil {
+			return err
+		}
+		*e = ChanUpdateChanFlags(b[0])
 	case *ErrorCode:
 		var b [2]byte
 		if _, err := io.ReadFull(r, b[:]); err != nil {

lnwire/lnwire_test.go

@@ -178,6 +178,50 @@ func randAddrs(r *rand.Rand) ([]net.Addr, error) {
 	return []net.Addr{tcp4Addr, tcp6Addr, v2OnionAddr, v3OnionAddr}, nil
 }
 
+// TestChanUpdateChanFlags ensures that converting the ChanUpdateChanFlags and
+// ChanUpdateMsgFlags bitfields to a string behaves as expected.
+func TestChanUpdateChanFlags(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		flags    uint8
+		expected string
+	}{
+		{
+			flags:    0,
+			expected: "00000000",
+		},
+		{
+			flags:    1,
+			expected: "00000001",
+		},
+		{
+			flags:    3,
+			expected: "00000011",
+		},
+		{
+			flags:    255,
+			expected: "11111111",
+		},
+	}
+
+	for _, test := range testCases {
+		chanFlag := ChanUpdateChanFlags(test.flags)
+		toStr := chanFlag.String()
+		if toStr != test.expected {
+			t.Fatalf("expected %v, got %v",
+				test.expected, toStr)
+		}
+
+		msgFlag := ChanUpdateMsgFlags(test.flags)
+		toStr = msgFlag.String()
+		if toStr != test.expected {
+			t.Fatalf("expected %v, got %v",
+				test.expected, toStr)
+		}
+	}
+}
+
 func TestMaxOutPointIndex(t *testing.T) {
 	t.Parallel()
 
@@ -605,12 +649,26 @@ func TestLightningWireProtocol(t *testing.T) {
 		},
 		MsgChannelUpdate: func(v []reflect.Value, r *rand.Rand) {
 			var err error
+
+			msgFlags := ChanUpdateMsgFlags(r.Int31())
+			maxHtlc := MilliSatoshi(r.Int63())
+
+			// We make the max_htlc field zero if it is not flagged
+			// as being part of the ChannelUpdate, to pass
+			// serialization tests, as it will be ignored if the bit
+			// is not set.
+			if msgFlags&ChanUpdateOptionMaxHtlc == 0 {
+				maxHtlc = 0
+			}
+
 			req := ChannelUpdate{
 				ShortChannelID:  NewShortChanIDFromInt(uint64(r.Int63())),
 				Timestamp:       uint32(r.Int31()),
-				Flags:           ChanUpdateFlag(r.Int31()),
+				MessageFlags:    msgFlags,
+				ChannelFlags:    ChanUpdateChanFlags(r.Int31()),
 				TimeLockDelta:   uint16(r.Int31()),
 				HtlcMinimumMsat: MilliSatoshi(r.Int63()),
+				HtlcMaximumMsat: maxHtlc,
 				BaseFee:         uint32(r.Int31()),
 				FeeRate:         uint32(r.Int31()),
 			}

lnwire/onion_error_test.go

@@ -20,7 +20,8 @@ var (
 		Signature:      sig,
 		ShortChannelID: NewShortChanIDFromInt(1),
 		Timestamp:      1,
-		Flags:          1,
+		MessageFlags:   0,
+		ChannelFlags:   1,
 	}
 )
 

peer.go

@@ -1235,10 +1235,10 @@ func messageSummary(msg lnwire.Message) string {
 			msg.ChainHash, msg.ShortChannelID.ToUint64())
 
 	case *lnwire.ChannelUpdate:
-		return fmt.Sprintf("chain_hash=%v, short_chan_id=%v, flag=%v, "+
-			"update_time=%v", msg.ChainHash,
-			msg.ShortChannelID.ToUint64(), msg.Flags,
-			time.Unix(int64(msg.Timestamp), 0))
+		return fmt.Sprintf("chain_hash=%v, short_chan_id=%v, "+
+			"mflags=%v, cflags=%v, update_time=%v", msg.ChainHash,
+			msg.ShortChannelID.ToUint64(), msg.MessageFlags,
+			msg.ChannelFlags, time.Unix(int64(msg.Timestamp), 0))
 
 	case *lnwire.NodeAnnouncement:
 		return fmt.Sprintf("node=%x, update_time=%v",

routing/ann_validation.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/btcsuite/btcd/btcec"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
+	"github.com/btcsuite/btcutil"
 	"github.com/davecgh/go-spew/spew"
 	"github.com/go-errors/errors"
 	"github.com/lightningnetwork/lnd/lnwire"
@@ -121,11 +122,16 @@ func ValidateNodeAnn(a *lnwire.NodeAnnouncement) error {
 }
 
 // ValidateChannelUpdateAnn validates the channel update announcement by
-// checking that the included signature covers he announcement and has been
-// signed by the node's private key.
-func ValidateChannelUpdateAnn(pubKey *btcec.PublicKey,
+// checking (1) that the included signature covers the announcement and has been
+// signed by the node's private key, and (2) that the announcement's message
+// flags and optional fields are sane.
+func ValidateChannelUpdateAnn(pubKey *btcec.PublicKey, capacity btcutil.Amount,
 	a *lnwire.ChannelUpdate) error {
 
+	if err := validateOptionalFields(capacity, a); err != nil {
+		return err
+	}
+
 	data, err := a.DataToSign()
 	if err != nil {
 		return errors.Errorf("unable to reconstruct message: %v", err)
@@ -144,3 +150,25 @@ func ValidateChannelUpdateAnn(pubKey *btcec.PublicKey,
 
 	return nil
 }
+
+// validateOptionalFields validates a channel update's message flags and
+// corresponding update fields.
+func validateOptionalFields(capacity btcutil.Amount,
+	msg *lnwire.ChannelUpdate) error {
+
+	if msg.MessageFlags.HasMaxHtlc() {
+		maxHtlc := msg.HtlcMaximumMsat
+		if maxHtlc == 0 || maxHtlc < msg.HtlcMinimumMsat {
+			return errors.Errorf("invalid max htlc for channel "+
+				"update %v", spew.Sdump(msg))
+		}
+		cap := lnwire.NewMSatFromSatoshis(capacity)
+		if maxHtlc > cap {
+			return errors.Errorf("max_htlc(%v) for channel "+
+				"update greater than capacity(%v)", maxHtlc,
+				cap)
+		}
+	}
+
+	return nil
+}

routing/notifications.go

@@ -339,7 +339,7 @@ func addToTopologyChange(graph *channeldb.ChannelGraph, update *TopologyChange,
 		// the second node.
 		sourceNode := edgeInfo.NodeKey1
 		connectingNode := edgeInfo.NodeKey2
-		if m.Flags&lnwire.ChanUpdateDirection == 1 {
+		if m.ChannelFlags&lnwire.ChanUpdateDirection == 1 {
 			sourceNode = edgeInfo.NodeKey2
 			connectingNode = edgeInfo.NodeKey1
 		}
@@ -363,7 +363,7 @@ func addToTopologyChange(graph *channeldb.ChannelGraph, update *TopologyChange,
 			FeeRate:         m.FeeProportionalMillionths,
 			AdvertisingNode: aNode,
 			ConnectingNode:  cNode,
-			Disabled:        m.Flags&lnwire.ChanUpdateDisabled != 0,
+			Disabled:        m.ChannelFlags&lnwire.ChanUpdateDisabled != 0,
 		}
 		edgeUpdate.AdvertisingNode.Curve = nil
 		edgeUpdate.ConnectingNode.Curve = nil

routing/notifications_test.go

@@ -402,9 +402,9 @@ func TestEdgeUpdateNotification(t *testing.T) {
 	// Create random policy edges that are stemmed to the channel id
 	// created above.
 	edge1 := randEdgePolicy(chanID, node1)
-	edge1.Flags = 0
+	edge1.ChannelFlags = 0
 	edge2 := randEdgePolicy(chanID, node2)
-	edge2.Flags = 1
+	edge2.ChannelFlags = 1
 
 	if err := ctx.router.UpdateEdge(edge1); err != nil {
 		t.Fatalf("unable to add edge update: %v", err)

routing/pathfind.go

@@ -562,7 +562,7 @@ func findPath(g *graphParams, r *restrictParams,
 		// TODO(halseth): also ignore disable flags for non-local
 		// channels if bandwidth hint is set?
 		isSourceChan := fromVertex == sourceVertex
-		edgeFlags := lnwire.ChanUpdateFlag(edge.Flags)
+		edgeFlags := edge.ChannelFlags
 		isDisabled := edgeFlags&lnwire.ChanUpdateDisabled != 0
 
 		if !isSourceChan && isDisabled {

routing/pathfind_test.go

@@ -271,7 +271,8 @@ func parseTestGraph(path string) (*testGraphInstance, error) {
 
 		edgePolicy := &channeldb.ChannelEdgePolicy{
 			SigBytes:                  testSig.Serialize(),
-			Flags:                     lnwire.ChanUpdateFlag(edge.Flags),
+			MessageFlags:              lnwire.ChanUpdateMsgFlags(edge.Flags >> 8),
+			ChannelFlags:              lnwire.ChanUpdateChanFlags(edge.Flags),
 			ChannelID:                 edge.ChannelID,
 			LastUpdate:                testTime,
 			TimeLockDelta:             edge.Expiry,
@@ -487,7 +488,8 @@ func createTestGraphFromChannels(testChannels []*testChannel) (*testGraphInstanc
 
 		edgePolicy := &channeldb.ChannelEdgePolicy{
 			SigBytes:                  testSig.Serialize(),
-			Flags:                     lnwire.ChanUpdateFlag(0),
+			MessageFlags:              0,
+			ChannelFlags:              0,
 			ChannelID:                 channelID,
 			LastUpdate:                testTime,
 			TimeLockDelta:             testChannel.Node1.Expiry,
@@ -501,7 +503,8 @@ func createTestGraphFromChannels(testChannels []*testChannel) (*testGraphInstanc
 
 		edgePolicy = &channeldb.ChannelEdgePolicy{
 			SigBytes:                  testSig.Serialize(),
-			Flags:                     lnwire.ChanUpdateFlag(lnwire.ChanUpdateDirection),
+			MessageFlags:              0,
+			ChannelFlags:              lnwire.ChanUpdateDirection,
 			ChannelID:                 channelID,
 			LastUpdate:                testTime,
 			TimeLockDelta:             testChannel.Node2.Expiry,
@@ -1476,11 +1479,11 @@ func TestRouteFailDisabledEdge(t *testing.T) {
 	if err != nil {
 		t.Fatalf("unable to fetch edge: %v", err)
 	}
-	e1.Flags |= lnwire.ChanUpdateDisabled
+	e1.ChannelFlags |= lnwire.ChanUpdateDisabled
 	if err := graph.graph.UpdateEdgePolicy(e1); err != nil {
 		t.Fatalf("unable to update edge: %v", err)
 	}
-	e2.Flags |= lnwire.ChanUpdateDisabled
+	e2.ChannelFlags |= lnwire.ChanUpdateDisabled
 	if err := graph.graph.UpdateEdgePolicy(e2); err != nil {
 		t.Fatalf("unable to update edge: %v", err)
 	}
@@ -1507,7 +1510,7 @@ func TestRouteFailDisabledEdge(t *testing.T) {
 	if err != nil {
 		t.Fatalf("unable to fetch edge: %v", err)
 	}
-	e.Flags |= lnwire.ChanUpdateDisabled
+	e.ChannelFlags |= lnwire.ChanUpdateDisabled
 	if err := graph.graph.UpdateEdgePolicy(e); err != nil {
 		t.Fatalf("unable to update edge: %v", err)
 	}
@@ -1627,11 +1630,11 @@ func TestPathSourceEdgesBandwidth(t *testing.T) {
 	if err != nil {
 		t.Fatalf("unable to fetch edge: %v", err)
 	}
-	e1.Flags |= lnwire.ChanUpdateDisabled
+	e1.ChannelFlags |= lnwire.ChanUpdateDisabled
 	if err := graph.graph.UpdateEdgePolicy(e1); err != nil {
 		t.Fatalf("unable to update edge: %v", err)
 	}
-	e2.Flags |= lnwire.ChanUpdateDisabled
+	e2.ChannelFlags |= lnwire.ChanUpdateDisabled
 	if err := graph.graph.UpdateEdgePolicy(e2); err != nil {
 		t.Fatalf("unable to update edge: %v", err)
 	}

routing/router.go

@@ -84,7 +84,7 @@ type ChannelGraphSource interface {
 	// edge for the passed channel ID (and flags) that have a more recent
 	// timestamp.
 	IsStaleEdgePolicy(chanID lnwire.ShortChannelID, timestamp time.Time,
-		flags lnwire.ChanUpdateFlag) bool
+		flags lnwire.ChanUpdateChanFlags) bool
 
 	// ForAllOutgoingChannels is used to iterate over all channels
 	// emanating from the "source" node which is the center of the
@@ -243,7 +243,7 @@ func newEdgeLocatorByPubkeys(channelID uint64, fromNode, toNode *Vertex) *edgeLo
 func newEdgeLocator(edge *channeldb.ChannelEdgePolicy) *edgeLocator {
 	return &edgeLocator{
 		channelID: edge.ChannelID,
-		direction: uint8(edge.Flags & lnwire.ChanUpdateDirection),
+		direction: uint8(edge.ChannelFlags & lnwire.ChanUpdateDirection),
 	}
 }
 
@@ -1149,25 +1149,26 @@ func (r *ChannelRouter) processUpdate(msg interface{}) error {
 
 		// A flag set of 0 indicates this is an announcement for the
 		// "first" node in the channel.
-		case msg.Flags&lnwire.ChanUpdateDirection == 0:
+		case msg.ChannelFlags&lnwire.ChanUpdateDirection == 0:
 
 			// Ignore outdated message.
 			if !edge1Timestamp.Before(msg.LastUpdate) {
 				return newErrf(ErrOutdated, "Ignoring "+
-					"outdated update (flags=%v) for known "+
-					"chan_id=%v", msg.Flags, msg.ChannelID)
-
+					"outdated update (flags=%v|%v) for "+
+					"known chan_id=%v", msg.MessageFlags,
+					msg.ChannelFlags, msg.ChannelID)
 			}
 
 		// Similarly, a flag set of 1 indicates this is an announcement
 		// for the "second" node in the channel.
-		case msg.Flags&lnwire.ChanUpdateDirection == 1:
+		case msg.ChannelFlags&lnwire.ChanUpdateDirection == 1:
 
 			// Ignore outdated message.
 			if !edge2Timestamp.Before(msg.LastUpdate) {
 				return newErrf(ErrOutdated, "Ignoring "+
-					"outdated update (flags=%v) for known "+
-					"chan_id=%v", msg.Flags, msg.ChannelID)
+					"outdated update (flags=%v|%v) for "+
+					"known chan_id=%v", msg.MessageFlags,
+					msg.ChannelFlags, msg.ChannelID)
 			}
 		}
 
@@ -2059,18 +2060,26 @@ func (r *ChannelRouter) applyChannelUpdate(msg *lnwire.ChannelUpdate,
 		return true
 	}
 
-	if err := ValidateChannelUpdateAnn(pubKey, msg); err != nil {
+	ch, _, _, err := r.GetChannelByID(msg.ShortChannelID)
+	if err != nil {
+		log.Errorf("Unable to retrieve channel by id: %v", err)
+		return false
+	}
+
+	if err := ValidateChannelUpdateAnn(pubKey, ch.Capacity, msg); err != nil {
 		log.Errorf("Unable to validate channel update: %v", err)
 		return false
 	}
 
-	err := r.UpdateEdge(&channeldb.ChannelEdgePolicy{
+	err = r.UpdateEdge(&channeldb.ChannelEdgePolicy{
 		SigBytes:                  msg.Signature.ToSignatureBytes(),
 		ChannelID:                 msg.ShortChannelID.ToUint64(),
 		LastUpdate:                time.Unix(int64(msg.Timestamp), 0),
-		Flags:                     msg.Flags,
+		MessageFlags:              msg.MessageFlags,
+		ChannelFlags:              msg.ChannelFlags,
 		TimeLockDelta:             msg.TimeLockDelta,
 		MinHTLC:                   msg.HtlcMinimumMsat,
+		MaxHTLC:                   msg.HtlcMaximumMsat,
 		FeeBaseMSat:               lnwire.MilliSatoshi(msg.BaseFee),
 		FeeProportionalMillionths: lnwire.MilliSatoshi(msg.FeeRate),
 	})
@@ -2270,7 +2279,7 @@ func (r *ChannelRouter) IsKnownEdge(chanID lnwire.ShortChannelID) bool {
 //
 // NOTE: This method is part of the ChannelGraphSource interface.
 func (r *ChannelRouter) IsStaleEdgePolicy(chanID lnwire.ShortChannelID,
-	timestamp time.Time, flags lnwire.ChanUpdateFlag) bool {
+	timestamp time.Time, flags lnwire.ChanUpdateChanFlags) bool {
 
 	edge1Timestamp, edge2Timestamp, exists, err := r.cfg.Graph.HasChannelEdge(
 		chanID.ToUint64(),

routing/router_test.go

@@ -550,7 +550,8 @@ func TestSendPaymentErrorRepeatedFeeInsufficient(t *testing.T) {
 	errChanUpdate := lnwire.ChannelUpdate{
 		ShortChannelID:  lnwire.NewShortChanIDFromInt(chanID),
 		Timestamp:       uint32(edgeUpateToFail.LastUpdate.Unix()),
-		Flags:           edgeUpateToFail.Flags,
+		MessageFlags:    edgeUpateToFail.MessageFlags,
+		ChannelFlags:    edgeUpateToFail.ChannelFlags,
 		TimeLockDelta:   edgeUpateToFail.TimeLockDelta,
 		HtlcMinimumMsat: edgeUpateToFail.MinHTLC,
 		BaseFee:         uint32(edgeUpateToFail.FeeBaseMSat),
@@ -656,7 +657,8 @@ func TestSendPaymentErrorNonFinalTimeLockErrors(t *testing.T) {
 	errChanUpdate := lnwire.ChannelUpdate{
 		ShortChannelID:  lnwire.NewShortChanIDFromInt(chanID),
 		Timestamp:       uint32(edgeUpateToFail.LastUpdate.Unix()),
-		Flags:           edgeUpateToFail.Flags,
+		MessageFlags:    edgeUpateToFail.MessageFlags,
+		ChannelFlags:    edgeUpateToFail.ChannelFlags,
 		TimeLockDelta:   edgeUpateToFail.TimeLockDelta,
 		HtlcMinimumMsat: edgeUpateToFail.MinHTLC,
 		BaseFee:         uint32(edgeUpateToFail.FeeBaseMSat),
@@ -1098,7 +1100,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 		FeeBaseMSat:               10,
 		FeeProportionalMillionths: 10000,
 	}
-	edgePolicy.Flags = 0
+	edgePolicy.ChannelFlags = 0
 
 	if err := ctx.router.UpdateEdge(edgePolicy); err != nil {
 		t.Fatalf("unable to update edge policy: %v", err)
@@ -1114,7 +1116,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 		FeeBaseMSat:               10,
 		FeeProportionalMillionths: 10000,
 	}
-	edgePolicy.Flags = 1
+	edgePolicy.ChannelFlags = 1
 
 	if err := ctx.router.UpdateEdge(edgePolicy); err != nil {
 		t.Fatalf("unable to update edge policy: %v", err)
@@ -1194,7 +1196,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 		FeeBaseMSat:               10,
 		FeeProportionalMillionths: 10000,
 	}
-	edgePolicy.Flags = 0
+	edgePolicy.ChannelFlags = 0
 
 	if err := ctx.router.UpdateEdge(edgePolicy); err != nil {
 		t.Fatalf("unable to update edge policy: %v", err)
@@ -1209,7 +1211,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 		FeeBaseMSat:               10,
 		FeeProportionalMillionths: 10000,
 	}
-	edgePolicy.Flags = 1
+	edgePolicy.ChannelFlags = 1
 
 	if err := ctx.router.UpdateEdge(edgePolicy); err != nil {
 		t.Fatalf("unable to update edge policy: %v", err)
@@ -2099,7 +2101,7 @@ func TestIsStaleEdgePolicy(t *testing.T) {
 		FeeBaseMSat:               10,
 		FeeProportionalMillionths: 10000,
 	}
-	edgePolicy.Flags = 0
+	edgePolicy.ChannelFlags = 0
 	if err := ctx.router.UpdateEdge(edgePolicy); err != nil {
 		t.Fatalf("unable to update edge policy: %v", err)
 	}
@@ -2113,7 +2115,7 @@ func TestIsStaleEdgePolicy(t *testing.T) {
 		FeeBaseMSat:               10,
 		FeeProportionalMillionths: 10000,
 	}
-	edgePolicy.Flags = 1
+	edgePolicy.ChannelFlags = 1
 	if err := ctx.router.UpdateEdge(edgePolicy); err != nil {
 		t.Fatalf("unable to update edge policy: %v", err)
 	}

rpcserver.go

@@ -3780,7 +3780,7 @@ func marshalDbEdge(edgeInfo *channeldb.ChannelEdgeInfo,
 			MinHtlc:          int64(c1.MinHTLC),
 			FeeBaseMsat:      int64(c1.FeeBaseMSat),
 			FeeRateMilliMsat: int64(c1.FeeProportionalMillionths),
-			Disabled:         c1.Flags&lnwire.ChanUpdateDisabled != 0,
+			Disabled:         c1.ChannelFlags&lnwire.ChanUpdateDisabled != 0,
 		}
 	}
 
@@ -3790,7 +3790,7 @@ func marshalDbEdge(edgeInfo *channeldb.ChannelEdgeInfo,
 			MinHtlc:          int64(c2.MinHTLC),
 			FeeBaseMsat:      int64(c2.FeeBaseMSat),
 			FeeRateMilliMsat: int64(c2.FeeProportionalMillionths),
-			Disabled:         c2.Flags&lnwire.ChanUpdateDisabled != 0,
+			Disabled:         c2.ChannelFlags&lnwire.ChanUpdateDisabled != 0,
 		}
 	}
 

server.go

@@ -2978,10 +2978,10 @@ func (s *server) announceChanStatus(op wire.OutPoint, disabled bool) error {
 
 	if disabled {
 		// Set the bit responsible for marking a channel as disabled.
-		chanUpdate.Flags |= lnwire.ChanUpdateDisabled
+		chanUpdate.ChannelFlags |= lnwire.ChanUpdateDisabled
 	} else {
 		// Clear the bit responsible for marking a channel as disabled.
-		chanUpdate.Flags &= ^lnwire.ChanUpdateDisabled
+		chanUpdate.ChannelFlags &= ^lnwire.ChanUpdateDisabled
 	}
 
 	// We must now update the message's timestamp and generate a new
@@ -3066,9 +3066,9 @@ func extractChannelUpdate(ownerPubKey []byte,
 	owner := func(edge *channeldb.ChannelEdgePolicy) []byte {
 		var pubKey *btcec.PublicKey
 		switch {
-		case edge.Flags&lnwire.ChanUpdateDirection == 0:
+		case edge.ChannelFlags&lnwire.ChanUpdateDirection == 0:
 			pubKey, _ = info.NodeKey1()
-		case edge.Flags&lnwire.ChanUpdateDirection == 1:
+		case edge.ChannelFlags&lnwire.ChanUpdateDirection == 1:
 			pubKey, _ = info.NodeKey2()
 		}
 
@@ -3100,9 +3100,11 @@ func createChannelUpdate(info *channeldb.ChannelEdgeInfo,
 		ChainHash:       info.ChainHash,
 		ShortChannelID:  lnwire.NewShortChanIDFromInt(policy.ChannelID),
 		Timestamp:       uint32(policy.LastUpdate.Unix()),
-		Flags:           policy.Flags,
+		MessageFlags:    policy.MessageFlags,
+		ChannelFlags:    policy.ChannelFlags,
 		TimeLockDelta:   policy.TimeLockDelta,
 		HtlcMinimumMsat: policy.MinHTLC,
+		HtlcMaximumMsat: policy.MaxHTLC,
 		BaseFee:         uint32(policy.FeeBaseMSat),
 		FeeRate:         uint32(policy.FeeProportionalMillionths),
 		ExtraOpaqueData: policy.ExtraOpaqueData,