multi: stop casting peer warning messages as errors

Split the logic for processing `error` and `warning` messages from our
peers.

funding/manager.go

@@ -859,15 +859,23 @@ func (f *Manager) reservationCoordinator() {
 			switch msg := fmsg.msg.(type) {
 			case *lnwire.OpenChannel:
 				f.handleFundingOpen(fmsg.peer, msg)
+
 			case *lnwire.AcceptChannel:
 				f.handleFundingAccept(fmsg.peer, msg)
+
 			case *lnwire.FundingCreated:
 				f.handleFundingCreated(fmsg.peer, msg)
+
 			case *lnwire.FundingSigned:
 				f.handleFundingSigned(fmsg.peer, msg)
+
 			case *lnwire.FundingLocked:
 				f.wg.Add(1)
 				go f.handleFundingLocked(fmsg.peer, msg)
+
+			case *lnwire.Warning:
+				f.handleWarningMsg(fmsg.peer, msg)
+
 			case *lnwire.Error:
 				f.handleErrorMsg(fmsg.peer, msg)
 			}
@@ -4193,12 +4201,16 @@ func (f *Manager) handleInitFundingMsg(msg *InitFundingMsg) {
 	}
 }
 
+// handleWarningMsg processes the warning which was received from remote peer.
+func (f *Manager) handleWarningMsg(peer lnpeer.Peer, msg *lnwire.Warning) {
+	log.Warnf("received warning message from peer %x: %v",
+		peer.IdentityKey().SerializeCompressed(), msg.Warning())
+}
+
 // handleErrorMsg processes the error which was received from remote peer,
 // depending on the type of error we should do different clean up steps and
 // inform the user about it.
-func (f *Manager) handleErrorMsg(peer lnpeer.Peer,
-	msg *lnwire.Error) {
-
+func (f *Manager) handleErrorMsg(peer lnpeer.Peer, msg *lnwire.Error) {
 	chanID := msg.ChanID
 	peerKey := peer.IdentityKey()
 

funding/manager_test.go

@@ -774,6 +774,14 @@ func fundChannel(t *testing.T, alice, bob *testNode, localFundingAmt,
 	// Forward the response to Alice.
 	alice.fundingMgr.ProcessFundingMsg(acceptChannelResponse, bob)
 
+	// Check that sending warning messages does not abort the funding
+	// process.
+	warningMsg := &lnwire.Warning{
+		Data: []byte("random warning"),
+	}
+	alice.fundingMgr.ProcessFundingMsg(warningMsg, bob)
+	bob.fundingMgr.ProcessFundingMsg(warningMsg, alice)
+
 	// Alice responds with a FundingCreated message.
 	fundingCreated := assertFundingMsgSent(
 		t, alice.msgChan, "FundingCreated",

htlcswitch/link.go

@@ -2069,7 +2069,7 @@ func (l *channelLink) handleUpstreamMsg(msg lnwire.Message) {
 	// although we "MAY" do so according to the specification.
 	case *lnwire.Warning:
 		l.log.Warnf("received warning message from peer: %v",
-			msg.Error.Error())
+			msg.Warning())
 
 	case *lnwire.Error:
 		// Error received from remote, MUST fail channel, but should

htlcswitch/link_test.go

@@ -5196,13 +5196,21 @@ func TestChannelLinkFail(t *testing.T) {
 	t.Parallel()
 
 	testCases := []struct {
+		// name is the description for this test case.
+		name string
+
 		// options is used to set up mocks and configure the link
 		// before it is started.
 		options func(*channelLink)
 
 		// link test is used to execute the given test on the channel
 		// link after it is started.
-		linkTest func(*testing.T, *channelLink, *lnwallet.LightningChannel)
+		linkTest func(*testing.T, *channelLink,
+			*lnwallet.LightningChannel)
+
+		// shouldFail indicates whether or not the link should fail
+		// during this test case.
+		shouldFail bool
 
 		// shouldForceClose indicates whether we expect the link to
 		// force close the channel in response to the actions performed
@@ -5215,8 +5223,24 @@ func TestChannelLinkFail(t *testing.T) {
 		permanentFailure bool
 	}{
 		{
-			// Test that we don't force close if syncing states
-			// fails at startup.
+			"don't fail the channel if we receive a warning " +
+				"message",
+			func(c *channelLink) {
+			},
+			func(_ *testing.T, c *channelLink,
+				_ *lnwallet.LightningChannel) {
+
+				warningMsg := &lnwire.Warning{
+					Data: []byte("random warning"),
+				}
+				c.HandleChannelUpdate(warningMsg)
+			},
+			false,
+			false,
+			false,
+		},
+		{
+			"don't force close if syncing states fails at startup",
 			func(c *channelLink) {
 				c.cfg.SyncStates = true
 
@@ -5224,15 +5248,18 @@ func TestChannelLinkFail(t *testing.T) {
 				// the SendMessage call fail.
 				c.cfg.Peer.(*mockPeer).disconnected = true
 			},
-			func(t *testing.T, c *channelLink, _ *lnwallet.LightningChannel) {
+			func(*testing.T, *channelLink,
+				*lnwallet.LightningChannel) { // nolint:whitespace,lll
+
 				// Should fail at startup.
 			},
+			true,
 			false,
 			false,
 		},
 		{
-			// Test that we don't force closes the channel if
-			// resolving forward packages fails at startup.
+			"we don't force closes the channel if resolving " +
+				"forward packages fails at startup",
 			func(c *channelLink) {
 				// We make the call to resolveFwdPkgs fail by
 				// making the underlying forwarder fail.
@@ -5241,18 +5268,23 @@ func TestChannelLinkFail(t *testing.T) {
 				}
 				c.channel.State().Packager = pkg
 			},
-			func(t *testing.T, c *channelLink, _ *lnwallet.LightningChannel) {
+			func(*testing.T, *channelLink,
+				*lnwallet.LightningChannel) { // nolint:whitespace,lll
+
 				// Should fail at startup.
 			},
+			true,
 			false,
 			false,
 		},
 		{
-			// Test that we don't force close the channel if we
-			// receive an invalid Settle message.
+			"don't force close the channel if we receive an " +
+				"invalid Settle message",
 			func(c *channelLink) {
 			},
-			func(t *testing.T, c *channelLink, _ *lnwallet.LightningChannel) {
+			func(_ *testing.T, c *channelLink,
+				_ *lnwallet.LightningChannel) {
+
 				// Recevive an htlc settle for an htlc that was
 				// never added.
 				htlcSettle := &lnwire.UpdateFulfillHTLC{
@@ -5261,16 +5293,17 @@ func TestChannelLinkFail(t *testing.T) {
 				}
 				c.HandleChannelUpdate(htlcSettle)
 			},
+			true,
 			false,
 			false,
 		},
 		{
-			// Test that we force close the channel if we receive
-			// an invalid CommitSig, not containing enough HTLC
-			// sigs.
+			"force close the channel if we receive an invalid " +
+				"CommitSig, not containing enough HTLC sigs",
 			func(c *channelLink) {
 			},
-			func(t *testing.T, c *channelLink, remoteChannel *lnwallet.LightningChannel) {
+			func(_ *testing.T, c *channelLink,
+				remoteChannel *lnwallet.LightningChannel) {
 
 				// Generate an HTLC and send to the link.
 				htlc1 := generateHtlc(t, c, 0)
@@ -5300,15 +5333,18 @@ func TestChannelLinkFail(t *testing.T) {
 				c.HandleChannelUpdate(commitSig)
 			},
 			true,
+			true,
 			false,
 		},
 		{
-			// Test that we force close the channel if we receive
-			// an invalid CommitSig, where the sig itself is
-			// corrupted.
+			"force close the channel if we receive an invalid " +
+				"CommitSig, where the sig itself is corrupted",
 			func(c *channelLink) {
 			},
-			func(t *testing.T, c *channelLink, remoteChannel *lnwallet.LightningChannel) {
+			func(t *testing.T, c *channelLink,
+				remoteChannel *lnwallet.LightningChannel) {
+
+				t.Helper()
 
 				// Generate an HTLC and send to the link.
 				htlc1 := generateHtlc(t, c, 0)
@@ -5340,17 +5376,21 @@ func TestChannelLinkFail(t *testing.T) {
 				c.HandleChannelUpdate(commitSig)
 			},
 			true,
+			true,
 			false,
 		},
 		{
-			// Test that we consider the failure permanent if we
-			// receive a link error from the remote.
+			"consider the failure permanent if we receive a link " +
+				"error from the remote",
 			func(c *channelLink) {
 			},
-			func(t *testing.T, c *channelLink, remoteChannel *lnwallet.LightningChannel) {
+			func(_ *testing.T, c *channelLink,
+				remoteChannel *lnwallet.LightningChannel) {
+
 				err := &lnwire.Error{}
 				c.HandleChannelUpdate(err)
 			},
+			true,
 			false,
 			// TODO(halseth) For compatibility with CL we currently
 			// don't treat Errors as permanent errors.
@@ -5361,12 +5401,10 @@ func TestChannelLinkFail(t *testing.T) {
 	const chanAmt = btcutil.SatoshiPerBitcoin * 5
 
 	// Execute each test case.
-	for i, test := range testCases {
+	for _, test := range testCases {
 		link, remoteChannel, _, start, _, err :=
 			newSingleLinkTestHarness(t, chanAmt, 0)
-		if err != nil {
-			t.Fatalf("unable to create link: %v", err)
-		}
+		require.NoError(t, err, test.name)
 
 		coreLink := link.(*channelLink)
 
@@ -5375,41 +5413,50 @@ func TestChannelLinkFail(t *testing.T) {
 		linkErrors := make(chan LinkFailureError, 1)
 		coreLink.cfg.OnChannelFailure = func(_ lnwire.ChannelID,
 			_ lnwire.ShortChannelID, linkErr LinkFailureError) {
+
 			linkErrors <- linkErr
 		}
 
 		// Set up the link before starting it.
 		test.options(coreLink)
-		if err := start(); err != nil {
-			t.Fatalf("unable to start test harness: %v", err)
-		}
+		err = start()
+		require.NoError(t, err, test.name)
 
 		// Execute the test case.
 		test.linkTest(t, coreLink, remoteChannel)
 
 		// Currently we expect all test cases to lead to link error.
 		var linkErr LinkFailureError
+		errReceived := false
 		select {
 		case linkErr = <-linkErrors:
+			errReceived = true
+
 		case <-time.After(10 * time.Second):
-			t.Fatalf("%d) Alice did not fail"+
-				"channel", i)
+			// If we do not receive a link error in 10s we assume
+			// that we won't receive any.
 		}
 
+		require.Equal(t, test.shouldFail, errReceived, test.name)
+
+		// Check that the link is up and return.
+		if !test.shouldFail {
+			require.False(t, coreLink.failed)
+			return
+		}
+
+		require.True(t, coreLink.failed)
+
 		// If we expect the link to force close the channel in this
 		// case, check that it happens. If not, make sure it does not
 		// happen.
-		if test.shouldForceClose != linkErr.ForceClose {
-			t.Fatalf("%d) Expected Alice to force close(%v), "+
-				"instead got(%v)", i, test.shouldForceClose,
-				linkErr.ForceClose)
-		}
-
-		if test.permanentFailure != linkErr.PermanentFailure {
-			t.Fatalf("%d) Expected Alice set permanent failure(%v), "+
-				"instead got(%v)", i, test.permanentFailure,
-				linkErr.PermanentFailure)
-		}
+		require.Equal(
+			t, test.shouldForceClose, linkErr.ForceClose, test.name,
+		)
+		require.Equal(
+			t, test.permanentFailure, linkErr.PermanentFailure,
+			test.name,
+		)
 	}
 }
 

lnwire/lnwire.go

@@ -91,60 +91,70 @@ func WriteElement(w *bytes.Buffer, element interface{}) error {
 		if _, err := w.Write(b[:]); err != nil {
 			return err
 		}
+
 	case uint8:
 		var b [1]byte
 		b[0] = e
 		if _, err := w.Write(b[:]); err != nil {
 			return err
 		}
+
 	case FundingFlag:
 		var b [1]byte
 		b[0] = uint8(e)
 		if _, err := w.Write(b[:]); err != nil {
 			return err
 		}
+
 	case uint16:
 		var b [2]byte
 		binary.BigEndian.PutUint16(b[:], e)
 		if _, err := w.Write(b[:]); err != nil {
 			return err
 		}
+
 	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
 		}
+
 	case MilliSatoshi:
 		var b [8]byte
 		binary.BigEndian.PutUint64(b[:], uint64(e))
 		if _, err := w.Write(b[:]); err != nil {
 			return err
 		}
+
 	case btcutil.Amount:
 		var b [8]byte
 		binary.BigEndian.PutUint64(b[:], uint64(e))
 		if _, err := w.Write(b[:]); err != nil {
 			return err
 		}
+
 	case uint32:
 		var b [4]byte
 		binary.BigEndian.PutUint32(b[:], e)
 		if _, err := w.Write(b[:]); err != nil {
 			return err
 		}
+
 	case uint64:
 		var b [8]byte
 		binary.BigEndian.PutUint64(b[:], e)
 		if _, err := w.Write(b[:]); err != nil {
 			return err
 		}
+
 	case *btcec.PublicKey:
 		if e == nil {
 			return fmt.Errorf("cannot write nil pubkey")
@@ -156,6 +166,7 @@ func WriteElement(w *bytes.Buffer, element interface{}) error {
 		if _, err := w.Write(b[:]); err != nil {
 			return err
 		}
+
 	case []Sig:
 		var b [2]byte
 		numSigs := uint16(len(e))
@@ -169,11 +180,13 @@ func WriteElement(w *bytes.Buffer, element interface{}) error {
 				return err
 			}
 		}
+
 	case Sig:
 		// Write buffer
 		if _, err := w.Write(e[:]); err != nil {
 			return err
 		}
+
 	case PingPayload:
 		var l [2]byte
 		binary.BigEndian.PutUint16(l[:], uint16(len(e)))
@@ -184,6 +197,7 @@ func WriteElement(w *bytes.Buffer, element interface{}) error {
 		if _, err := w.Write(e[:]); err != nil {
 			return err
 		}
+
 	case PongPayload:
 		var l [2]byte
 		binary.BigEndian.PutUint16(l[:], uint16(len(e)))
@@ -194,6 +208,18 @@ func WriteElement(w *bytes.Buffer, element interface{}) error {
 		if _, err := w.Write(e[:]); err != nil {
 			return err
 		}
+
+	case WarningData:
+		var l [2]byte
+		binary.BigEndian.PutUint16(l[:], uint16(len(e)))
+		if _, err := w.Write(l[:]); err != nil {
+			return err
+		}
+
+		if _, err := w.Write(e[:]); err != nil {
+			return err
+		}
+
 	case ErrorData:
 		var l [2]byte
 		binary.BigEndian.PutUint16(l[:], uint16(len(e)))
@@ -204,6 +230,7 @@ func WriteElement(w *bytes.Buffer, element interface{}) error {
 		if _, err := w.Write(e[:]); err != nil {
 			return err
 		}
+
 	case OpaqueReason:
 		var l [2]byte
 		binary.BigEndian.PutUint16(l[:], uint16(len(e)))
@@ -214,14 +241,17 @@ func WriteElement(w *bytes.Buffer, element interface{}) error {
 		if _, err := w.Write(e[:]); err != nil {
 			return err
 		}
+
 	case [33]byte:
 		if _, err := w.Write(e[:]); err != nil {
 			return err
 		}
+
 	case []byte:
 		if _, err := w.Write(e[:]); err != nil {
 			return err
 		}
+
 	case PkScript:
 		// The largest script we'll accept is a p2wsh which is exactly
 		// 34 bytes long.
@@ -233,6 +263,7 @@ func WriteElement(w *bytes.Buffer, element interface{}) error {
 		if err := wire.WriteVarBytes(w, 0, e); err != nil {
 			return err
 		}
+
 	case *RawFeatureVector:
 		if e == nil {
 			return fmt.Errorf("cannot write nil feature vector")
@@ -265,10 +296,12 @@ func WriteElement(w *bytes.Buffer, element interface{}) error {
 		if _, err := w.Write(e[:]); err != nil {
 			return err
 		}
+
 	case FailCode:
 		if err := WriteElement(w, uint16(e)); err != nil {
 			return err
 		}
+
 	case ShortChannelID:
 		// Check that field fit in 3 bytes and write the blockHeight
 		if e.BlockHeight > ((1 << 24) - 1) {
@@ -399,6 +432,7 @@ func WriteElement(w *bytes.Buffer, element interface{}) error {
 				return err
 			}
 		}
+
 	case color.RGBA:
 		if err := WriteElements(w, e.R, e.G, e.B); err != nil {
 			return err
@@ -473,68 +507,78 @@ func ReadElement(r io.Reader, element interface{}) error {
 		if err != nil {
 			return err
 		}
-
 		*e = alias
+
 	case *ShortChanIDEncoding:
 		var b [1]uint8
 		if _, err := r.Read(b[:]); err != nil {
 			return err
 		}
 		*e = ShortChanIDEncoding(b[0])
+
 	case *uint8:
 		var b [1]uint8
 		if _, err := r.Read(b[:]); err != nil {
 			return err
 		}
 		*e = b[0]
+
 	case *FundingFlag:
 		var b [1]uint8
 		if _, err := r.Read(b[:]); err != nil {
 			return err
 		}
 		*e = FundingFlag(b[0])
+
 	case *uint16:
 		var b [2]byte
 		if _, err := io.ReadFull(r, b[:]); err != nil {
 			return err
 		}
 		*e = binary.BigEndian.Uint16(b[:])
+
 	case *ChanUpdateMsgFlags:
 		var b [1]uint8
 		if _, err := r.Read(b[:]); err != nil {
 			return err
 		}
 		*e = ChanUpdateMsgFlags(b[0])
+
 	case *ChanUpdateChanFlags:
 		var b [1]uint8
 		if _, err := r.Read(b[:]); err != nil {
 			return err
 		}
 		*e = ChanUpdateChanFlags(b[0])
+
 	case *uint32:
 		var b [4]byte
 		if _, err := io.ReadFull(r, b[:]); err != nil {
 			return err
 		}
 		*e = binary.BigEndian.Uint32(b[:])
+
 	case *uint64:
 		var b [8]byte
 		if _, err := io.ReadFull(r, b[:]); err != nil {
 			return err
 		}
 		*e = binary.BigEndian.Uint64(b[:])
+
 	case *MilliSatoshi:
 		var b [8]byte
 		if _, err := io.ReadFull(r, b[:]); err != nil {
 			return err
 		}
 		*e = MilliSatoshi(int64(binary.BigEndian.Uint64(b[:])))
+
 	case *btcutil.Amount:
 		var b [8]byte
 		if _, err := io.ReadFull(r, b[:]); err != nil {
 			return err
 		}
 		*e = btcutil.Amount(int64(binary.BigEndian.Uint64(b[:])))
+
 	case **btcec.PublicKey:
 		var b [btcec.PubKeyBytesLenCompressed]byte
 		if _, err = io.ReadFull(r, b[:]); err != nil {
@@ -546,13 +590,13 @@ func ReadElement(r io.Reader, element interface{}) error {
 			return err
 		}
 		*e = pubKey
+
 	case **RawFeatureVector:
 		f := NewRawFeatureVector()
 		err = f.Decode(r)
 		if err != nil {
 			return err
 		}
-
 		*e = f
 
 	case *[]Sig:
@@ -571,13 +615,13 @@ func ReadElement(r io.Reader, element interface{}) error {
 				}
 			}
 		}
-
 		*e = sigs
 
 	case *Sig:
 		if _, err := io.ReadFull(r, e[:]); err != nil {
 			return err
 		}
+
 	case *OpaqueReason:
 		var l [2]byte
 		if _, err := io.ReadFull(r, l[:]); err != nil {
@@ -589,6 +633,19 @@ func ReadElement(r io.Reader, element interface{}) error {
 		if _, err := io.ReadFull(r, *e); err != nil {
 			return err
 		}
+
+	case *WarningData:
+		var l [2]byte
+		if _, err := io.ReadFull(r, l[:]); err != nil {
+			return err
+		}
+		errorLen := binary.BigEndian.Uint16(l[:])
+
+		*e = WarningData(make([]byte, errorLen))
+		if _, err := io.ReadFull(r, *e); err != nil {
+			return err
+		}
+
 	case *ErrorData:
 		var l [2]byte
 		if _, err := io.ReadFull(r, l[:]); err != nil {
@@ -600,6 +657,7 @@ func ReadElement(r io.Reader, element interface{}) error {
 		if _, err := io.ReadFull(r, *e); err != nil {
 			return err
 		}
+
 	case *PingPayload:
 		var l [2]byte
 		if _, err := io.ReadFull(r, l[:]); err != nil {
@@ -611,6 +669,7 @@ func ReadElement(r io.Reader, element interface{}) error {
 		if _, err := io.ReadFull(r, *e); err != nil {
 			return err
 		}
+
 	case *PongPayload:
 		var l [2]byte
 		if _, err := io.ReadFull(r, l[:]); err != nil {
@@ -622,20 +681,24 @@ func ReadElement(r io.Reader, element interface{}) error {
 		if _, err := io.ReadFull(r, *e); err != nil {
 			return err
 		}
+
 	case *[33]byte:
 		if _, err := io.ReadFull(r, e[:]); err != nil {
 			return err
 		}
+
 	case []byte:
 		if _, err := io.ReadFull(r, e); err != nil {
 			return err
 		}
+
 	case *PkScript:
 		pkScript, err := wire.ReadVarBytes(r, 0, 34, "pkscript")
 		if err != nil {
 			return err
 		}
 		*e = pkScript
+
 	case *wire.OutPoint:
 		var h [32]byte
 		if _, err = io.ReadFull(r, h[:]); err != nil {
@@ -657,10 +720,12 @@ func ReadElement(r io.Reader, element interface{}) error {
 			Hash:  *hash,
 			Index: uint32(index),
 		}
+
 	case *FailCode:
 		if err := ReadElement(r, (*uint16)(e)); err != nil {
 			return err
 		}
+
 	case *ChannelID:
 		if _, err := io.ReadFull(r, e[:]); err != nil {
 			return err
@@ -833,6 +898,7 @@ func ReadElement(r io.Reader, element interface{}) error {
 		}
 
 		*e = addresses
+
 	case *color.RGBA:
 		err := ReadElements(r,
 			&e.R,
@@ -842,6 +908,7 @@ func ReadElement(r io.Reader, element interface{}) error {
 		if err != nil {
 			return err
 		}
+
 	case *DeliveryAddress:
 		var addrLen [2]byte
 		if _, err = io.ReadFull(r, addrLen[:]); err != nil {

lnwire/warning.go

@@ -1,16 +1,70 @@
 package lnwire
 
+import (
+	"bytes"
+	"fmt"
+	"io"
+)
+
+// WarningData is a set of bytes associated with a particular sent warning. A
+// receiving node SHOULD only print out data verbatim if the string is composed
+// solely of printable ASCII characters. For reference, the printable character
+// set includes byte values 32 through 127 inclusive.
+type WarningData []byte
+
+// Warning is used to express non-critical errors in the protocol, providing
+// a "soft" way for nodes to communicate failures.
+type Warning struct {
+	// ChanID references the active channel in which the warning occurred
+	// within. If the ChanID is all zeros, then this warning applies to the
+	// entire established connection.
+	ChanID ChannelID
+
+	// Data is the attached warning data that describes the exact failure
+	// which caused the warning message to be sent.
+	Data WarningData
+}
+
 // 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
+// NewWarning creates a new Warning message.
+func NewWarning() *Warning {
+	return &Warning{}
+}
+
+// Warning returns the string representation to Warning.
+func (c *Warning) Warning() string {
+	errMsg := "non-ascii data"
+	if isASCII(c.Data) {
+		errMsg = string(c.Data)
+	}
+
+	return fmt.Sprintf("chan_id=%v, err=%v", c.ChanID, errMsg)
+}
+
+// Decode deserializes a serialized Warning message stored in the passed
+// io.Reader observing the specified protocol version.
+//
+// This is part of the lnwire.Message interface.
+func (c *Warning) Decode(r io.Reader, pver uint32) error {
+	return ReadElements(r,
+		&c.ChanID,
+		&c.Data,
+	)
+}
+
+// Encode serializes the target Warning into the passed io.Writer observing the
+// protocol version specified.
+//
+// This is part of the lnwire.Message interface.
+func (c *Warning) Encode(w *bytes.Buffer, pver uint32) error {
+	if err := WriteBytes(w, c.ChanID[:]); err != nil {
+		return err
+	}
+
+	return WriteWarningData(w, c.Data)
 }
 
 // MsgType returns the integer uniquely identifying an Warning message on the

lnwire/writer.go

@@ -241,6 +241,11 @@ func WritePongPayload(buf *bytes.Buffer, payload PongPayload) error {
 	return writeDataWithLength(buf, payload)
 }
 
+// WriteWarningData appends the data to the provided buffer.
+func WriteWarningData(buf *bytes.Buffer, data WarningData) error {
+	return writeDataWithLength(buf, data)
+}
+
 // WriteErrorData appends the data to the provided buffer.
 func WriteErrorData(buf *bytes.Buffer, data ErrorData) error {
 	return writeDataWithLength(buf, data)

peer/brontide.go

@@ -1539,7 +1539,7 @@ out:
 
 		case *lnwire.Warning:
 			targetChan = msg.ChanID
-			isLinkUpdate = p.handleError(&msg.Error)
+			isLinkUpdate = p.handleWarning(msg)
 
 		case *lnwire.Error:
 			targetChan = msg.ChanID
@@ -1675,6 +1675,38 @@ func (p *Brontide) storeError(err error) {
 	)
 }
 
+// handleWarning processes a warning message read from the remote peer. The
+// boolean return indicates whether the message should be delivered to a
+// targeted peer or not. The message gets stored in memory as an error if we
+// have open channels with the peer we received it from.
+//
+// NOTE: This method should only be called from within the readHandler.
+func (p *Brontide) handleWarning(msg *lnwire.Warning) bool {
+	switch {
+	// Connection wide messages should be forward the warning to all the
+	// channels with this peer.
+	case msg.ChanID == lnwire.ConnectionWideID:
+		for _, chanStream := range p.activeMsgStreams {
+			chanStream.AddMsg(msg)
+		}
+
+		return false
+
+	// If the channel ID for the warning message corresponds to a pending
+	// channel, then the funding manager will handle the warning.
+	case p.cfg.FundingManager.IsPendingChannel(msg.ChanID, p):
+		p.cfg.FundingManager.ProcessFundingMsg(msg, p)
+		return false
+
+	// If not we hand the warning to the channel link for this channel.
+	case p.isActiveChannel(msg.ChanID):
+		return true
+
+	default:
+		return false
+	}
+}
+
 // handleError processes an error message read from the remote peer. The boolean
 // returns indicates whether the message should be delivered to a targeted peer.
 // It stores the error we received from the peer in memory if we have a channel
@@ -1775,7 +1807,7 @@ func messageSummary(msg lnwire.Message) string {
 			msg.ChanID, msg.ID, msg.FailureCode)
 
 	case *lnwire.Warning:
-		return fmt.Sprintf("%v", msg.Error.Error())
+		return fmt.Sprintf("%v", msg.Warning())
 
 	case *lnwire.Error:
 		return fmt.Sprintf("%v", msg.Error())