lnwire: remove the HTLC timeout msg in favor of a HTLC cancel msg

This commit removes the previous HTLC timeout in message in favor of a
HTLC cancel message. Within the protocol, a timeout message would never
be sent backwards along the route as in the case of an HTLC timeout
before/after the grace period, the course of action taken would be to
broadcast the current commitment transaction unilaterally on-chain.

lnwire/htlc_cancel.go

@@ -0,0 +1,100 @@
+package lnwire
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/roasbeef/btcd/wire"
+)
+
+// CancelHTLC is sent by Alice to Bob in order to remove a previously added
+// HTLC. Upon receipt of an CancelHTLC the HTLC should be removed from the next
+// commitment transaction, with the CancelHTLC propgated backwards in the route
+// to fully un-clear the HTLC.
+type CancelHTLC struct {
+	// ChannelPoint is the particular active channel that this CancelHTLC
+	// is binded to.
+	ChannelPoint *wire.OutPoint
+
+	// HTLCKey references which HTLC on the remote node's commitment
+	// transaction has timed out.
+	HTLCKey HTLCKey
+}
+
+// Decode deserializes a serialized CancelHTLC message stored in the passed
+// io.Reader observing the specified protocol version.
+//
+// This is part of the lnwire.Message interface.
+func (c *CancelHTLC) Decode(r io.Reader, pver uint32) error {
+	// ChannelPoint(8)
+	// HTLCKey(8)
+	err := readElements(r,
+		&c.ChannelPoint,
+		&c.HTLCKey,
+	)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// CancelHTLC creates a new CancelHTLC message.
+func NewHTLCTimeoutRequest() *CancelHTLC {
+	return &CancelHTLC{}
+}
+
+// A compile time check to ensure CancelHTLC implements the lnwire.Message
+// interface.
+var _ Message = (*CancelHTLC)(nil)
+
+// Encode serializes the target CancelHTLC into the passed io.Writer observing
+// the protocol version specified.
+//
+// This is part of the lnwire.Message interface.
+func (c *CancelHTLC) Encode(w io.Writer, pver uint32) error {
+	err := writeElements(w,
+		c.ChannelPoint,
+		c.HTLCKey,
+	)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Command returns the integer uniquely identifying this message type on the
+// wire.
+//
+// This is part of the lnwire.Message interface.
+func (c *CancelHTLC) Command() uint32 {
+	return CmdCancelHTLC
+}
+
+// MaxPayloadLength returns the maximum allowed payload size for a CancelHTLC
+// complete message observing the specified protocol version.
+//
+// This is part of the lnwire.Message interface.
+func (c *CancelHTLC) MaxPayloadLength(uint32) uint32 {
+	// 36 + 8
+	return 44
+}
+
+// Validate performs any necessary sanity checks to ensure all fields present
+// on the CancelHTLC are valid.
+//
+// This is part of the lnwire.Message interface.
+func (c *CancelHTLC) Validate() error {
+	// We're good!
+	return nil
+}
+
+// String returns the string representation of the target CancelHTLC.  This is
+// part of the lnwire.Message interface.
+func (c *CancelHTLC) String() string {
+	return fmt.Sprintf("\n--- Begin CancelHTLC ---\n") +
+		fmt.Sprintf("ChannelPoint:\t%d\n", c.ChannelPoint) +
+		fmt.Sprintf("HTLCKey:\t%d\n", c.HTLCKey) +
+		fmt.Sprintf("--- End CancelHTLC ---\n")
+}

lnwire/htlc_cancel_test.go

@@ -0,0 +1,33 @@
+package lnwire
+
+import (
+	"bytes"
+	"reflect"
+	"testing"
+)
+
+func TestCancelHTLCEncodeDecode(t *testing.T) {
+	// First create a new HTLCTR message.
+	cancelMsg := &CancelHTLC{
+		ChannelPoint: outpoint1,
+		HTLCKey:      22,
+	}
+
+	// Next encode the HTLCTR message into an empty bytes buffer.
+	var b bytes.Buffer
+	if err := cancelMsg.Encode(&b, 0); err != nil {
+		t.Fatalf("unable to encode CancelHTLC: %v", err)
+	}
+
+	// Deserialize the encoded HTLCTR message into a new empty struct.
+	cancelMsg2 := &CancelHTLC{}
+	if err := cancelMsg2.Decode(&b, 0); err != nil {
+		t.Fatalf("unable to decode CancelHTLC: %v", err)
+	}
+
+	// Assert equality of the two instances.
+	if !reflect.DeepEqual(cancelMsg, cancelMsg2) {
+		t.Fatalf("encode/decode error messages don't match %#v vs %#v",
+			cancelMsg, cancelMsg2)
+	}
+}

lnwire/htlc_timeoutrequest.go

@@ -1,100 +0,0 @@
-package lnwire
-
-import (
-	"fmt"
-	"io"
-
-	"github.com/roasbeef/btcd/wire"
-)
-
-// HTLCTimeoutRequest is sent by Alice to Bob in order to timeout a previously
-// added HTLC. Upon receipt of an HTLCTimeoutRequest the HTLC should be removed
-// from the next commitment transaction, with the HTLCTimeoutRequest propgated
-// backwards in the route to fully clear the HTLC.
-type HTLCTimeoutRequest struct {
-	// ChannelPoint is the particular active channel that this HTLCTimeoutRequest
-	// is binded to.
-	ChannelPoint *wire.OutPoint
-
-	// HTLCKey references which HTLC on the remote node's commitment
-	// transaction has timed out.
-	HTLCKey HTLCKey
-}
-
-// Decode deserializes a serialized HTLCTimeoutRequest message stored in the passed
-// io.Reader observing the specified protocol version.
-//
-// This is part of the lnwire.Message interface.
-func (c *HTLCTimeoutRequest) Decode(r io.Reader, pver uint32) error {
-	// ChannelPoint(8)
-	// HTLCKey(8)
-	err := readElements(r,
-		&c.ChannelPoint,
-		&c.HTLCKey,
-	)
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
-// NewHTLCTimeoutRequest creates a new HTLCTimeoutRequest message.
-func NewHTLCTimeoutRequest() *HTLCTimeoutRequest {
-	return &HTLCTimeoutRequest{}
-}
-
-// A compile time check to ensure HTLCTimeoutRequest implements the lnwire.Message
-// interface.
-var _ Message = (*HTLCTimeoutRequest)(nil)
-
-// Encode serializes the target HTLCTimeoutRequest into the passed io.Writer observing
-// the protocol version specified.
-//
-// This is part of the lnwire.Message interface.
-func (c *HTLCTimeoutRequest) Encode(w io.Writer, pver uint32) error {
-	err := writeElements(w,
-		c.ChannelPoint,
-		c.HTLCKey,
-	)
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
-// Command returns the integer uniquely identifying this message type on the
-// wire.
-//
-// This is part of the lnwire.Message interface.
-func (c *HTLCTimeoutRequest) Command() uint32 {
-	return CmdHTLCTimeoutRequest
-}
-
-// MaxPayloadLength returns the maximum allowed payload size for a HTLCTimeoutRequest
-// complete message observing the specified protocol version.
-//
-// This is part of the lnwire.Message interface.
-func (c *HTLCTimeoutRequest) MaxPayloadLength(uint32) uint32 {
-	// 36 + 8
-	return 44
-}
-
-// Validate performs any necessary sanity checks to ensure all fields present
-// on the HTLCTimeoutRequest are valid.
-//
-// This is part of the lnwire.Message interface.
-func (c *HTLCTimeoutRequest) Validate() error {
-	// We're good!
-	return nil
-}
-
-// String returns the string representation of the target HTLCTimeoutRequest.  //
-// This is part of the lnwire.Message interface.
-func (c *HTLCTimeoutRequest) String() string {
-	return fmt.Sprintf("\n--- Begin HTLCTimeoutRequest ---\n") +
-		fmt.Sprintf("ChannelPoint:\t%d\n", c.ChannelPoint) +
-		fmt.Sprintf("HTLCKey:\t%d\n", c.HTLCKey) +
-		fmt.Sprintf("--- End HTLCTimeoutRequest ---\n")
-}

lnwire/htlc_timeoutrequest_test.go

@@ -1,33 +0,0 @@
-package lnwire
-
-import (
-	"bytes"
-	"reflect"
-	"testing"
-)
-
-func TestHTLCTimeoutRequestEncodeDecode(t *testing.T) {
-	// First create a new HTLCTR message.
-	timeoutReq := &HTLCTimeoutRequest{
-		ChannelPoint: outpoint1,
-		HTLCKey:      22,
-	}
-
-	// Next encode the HTLCTR message into an empty bytes buffer.
-	var b bytes.Buffer
-	if err := timeoutReq.Encode(&b, 0); err != nil {
-		t.Fatalf("unable to encode HTLCTimeoutRequest: %v", err)
-	}
-
-	// Deserialize the encoded HTLCTR message into a new empty struct.
-	timeoutReq2 := &HTLCTimeoutRequest{}
-	if err := timeoutReq2.Decode(&b, 0); err != nil {
-		t.Fatalf("unable to decode HTLCTimeoutRequest: %v", err)
-	}
-
-	// Assert equality of the two instances.
-	if !reflect.DeepEqual(timeoutReq, timeoutReq2) {
-		t.Fatalf("encode/decode error messages don't match %#v vs %#v",
-			timeoutReq, timeoutReq2)
-	}
-}

lnwire/message.go

@@ -38,7 +38,7 @@ const (
 	CmdHTLCAddAccept     = uint32(1010)
 	CmdHTLCAddReject     = uint32(1020)
 	CmdHTLCSettleRequest = uint32(1100)
-	CmdHTLCTimeoutRequest = uint32(1300)
+	CmdCancelHTLC        = uint32(1300)
 
 	// Commands for modifying commitment transactions.
 	CmdCommitSignature  = uint32(2000)
@@ -94,8 +94,8 @@ func makeEmptyMessage(command uint32) (Message, error) {
 		msg = &HTLCAddReject{}
 	case CmdHTLCSettleRequest:
 		msg = &HTLCSettleRequest{}
-	case CmdHTLCTimeoutRequest:
+	case CmdCancelHTLC:
-		msg = &HTLCTimeoutRequest{}
+		msg = &CancelHTLC{}
 	case CmdCommitSignature:
 		msg = &CommitSignature{}
 	case CmdCommitRevocation: