Merge pull request #6546 from carlaKC/bolts-950-warningmessage

lnwire/peer: add ability to read + log peer warning messages

docs/release-notes/release-notes-0.16.0.md

@@ -0,0 +1,8 @@
+# Release Notes
+
+## Misc
+* Warning messages from peers are now recognized and [logged](https://github.com/lightningnetwork/lnd/pull/6546) by lnd.
+
+# Contributors (Alphabetical Order)
+* Carla Kirk-Cohen
+

htlcswitch/link.go

@@ -2008,6 +2008,13 @@ func (l *channelLink) handleUpstreamMsg(msg lnwire.Message) {
 		// Update the mailbox's feerate as well.
 		l.mailBox.SetFeeRate(fee)
 
+	// In the case where we receive a warning message from our peer, just
+	// log it and move on. We choose not to disconnect from our peer,
+	// although we "MAY" do so according to the specification.
+	case *lnwire.Warning:
+		l.log.Warnf("received warning message from peer: %v",
+			msg.Error.Error())
+
 	case *lnwire.Error:
 		// Error received from remote, MUST fail channel, but should
 		// only print the contents of the error message if all

lnwire/lnwire_test.go

@@ -964,6 +964,12 @@ func TestLightningWireProtocol(t *testing.T) {
 				return mainScenario(&m)
 			},
 		},
+		{
+			msgType: MsgWarning,
+			scenario: func(m Warning) bool {
+				return mainScenario(&m)
+			},
+		},
 		{
 			msgType: MsgError,
 			scenario: func(m Error) bool {

lnwire/message.go

@@ -22,7 +22,8 @@ type MessageType uint16
 // The currently defined message types within this current version of the
 // Lightning protocol.
 const (
-	MsgInit                    MessageType = 16
+	MsgWarning                 MessageType = 1
+	MsgInit                                = 16
 	MsgError                               = 17
 	MsgPing                                = 18
 	MsgPong                                = 19
@@ -75,6 +76,8 @@ func ErrorPayloadTooLarge(size int) error {
 // String return the string representation of message type.
 func (t MessageType) String() string {
 	switch t {
+	case MsgWarning:
+		return "Warning"
 	case MsgInit:
 		return "Init"
 	case MsgOpenChannel:
@@ -175,6 +178,8 @@ func makeEmptyMessage(msgType MessageType) (Message, error) {
 	var msg Message
 
 	switch msgType {
+	case MsgWarning:
+		msg = &Warning{}
 	case MsgInit:
 		msg = &Init{}
 	case MsgOpenChannel:

lnwire/warning.go

@@ -0,0 +1,22 @@
+package lnwire
+
+// A compile time check to ensure Warning implements the lnwire.Message
+// interface.
+var _ Message = (*Warning)(nil)
+
+// Warning is used to express non-critical errors in the protocol, providing
+// a "soft" way for nodes to communicate failures. Since it has the same
+// structure as errors, warnings simply include an Error so that we can leverage
+// their encode/decode functionality, and over write the MsgType function to
+// differentiate them.
+type Warning struct {
+	Error
+}
+
+// MsgType returns the integer uniquely identifying an Warning message on the
+// wire.
+//
+// This is part of the lnwire.Message interface.
+func (c *Warning) MsgType() MessageType {
+	return MsgWarning
+}

peer/brontide.go

@@ -1455,6 +1455,10 @@ out:
 				break out
 			}
 
+		case *lnwire.Warning:
+			targetChan = msg.ChanID
+			isLinkUpdate = p.handleError(&msg.Error)
+
 		case *lnwire.Error:
 			targetChan = msg.ChanID
 			isLinkUpdate = p.handleError(msg)
@@ -1688,6 +1692,9 @@ func messageSummary(msg lnwire.Message) string {
 		return fmt.Sprintf("chan_id=%v, id=%v, fail_code=%v",
 			msg.ChanID, msg.ID, msg.FailureCode)
 
+	case *lnwire.Warning:
+		return fmt.Sprintf("%v", msg.Error.Error())
+
 	case *lnwire.Error:
 		return fmt.Sprintf("%v", msg.Error())