multi: stop casting peer warning messages as errors

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

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 {