peer+lnwire: add LinkUpdater iface and impl on relevant msgs

Removes longstanding TODO to simplify parsing of target chanid.

lnwire/commit_sig.go

@@ -1,6 +1,8 @@
 package lnwire
 
-import "io"
+import (
+	"io"
+)
 
 // CommitSig is sent by either side to stage any pending HTLC's in the
 // receiver's pending set into a new commitment state.  Implicitly, the new
@@ -83,3 +85,11 @@ func (c *CommitSig) MaxPayloadLength(uint32) uint32 {
 	// 32 + 64 + 2 + max_allowed_htlcs
 	return MaxMessagePayload
 }
+
+// TargetChanID returns the channel id of the link for which this message is
+// intended.
+//
+// NOTE: Part of lnd.LinkUpdater interface.
+func (c *CommitSig) TargetChanID() ChannelID {
+	return c.ChanID
+}

lnwire/revoke_and_ack.go

@@ -81,3 +81,11 @@ func (c *RevokeAndAck) MaxPayloadLength(uint32) uint32 {
 	// 32 + 32 + 33
 	return 97
 }
+
+// TargetChanID returns the channel id of the link for which this message is
+// intended.
+//
+// NOTE: Part of lnd.LinkUpdater interface.
+func (c *RevokeAndAck) TargetChanID() ChannelID {
+	return c.ChanID
+}

lnwire/update_add_htlc.go

@@ -1,6 +1,8 @@
 package lnwire
 
-import "io"
+import (
+	"io"
+)
 
 // OnionPacketSize is the size of the serialized Sphinx onion packet included
 // in each UpdateAddHTLC message. The breakdown of the onion packet is as
@@ -107,3 +109,11 @@ func (c *UpdateAddHTLC) MaxPayloadLength(uint32) uint32 {
 	// 1450
 	return 32 + 8 + 4 + 8 + 32 + 1366
 }
+
+// TargetChanID returns the channel id of the link for which this message is
+// intended.
+//
+// NOTE: Part of lnd.LinkUpdater interface.
+func (c *UpdateAddHTLC) TargetChanID() ChannelID {
+	return c.ChanID
+}

lnwire/update_fail_htlc.go

@@ -1,6 +1,8 @@
 package lnwire
 
-import "io"
+import (
+	"io"
+)
 
 // OpaqueReason is an opaque encrypted byte slice that encodes the exact
 // failure reason and additional some supplemental data. The contents of this
@@ -83,3 +85,11 @@ func (c *UpdateFailHTLC) MaxPayloadLength(uint32) uint32 {
 
 	return length
 }
+
+// TargetChanID returns the channel id of the link for which this message is
+// intended.
+//
+// NOTE: Part of lnd.LinkUpdater interface.
+func (c *UpdateFailHTLC) TargetChanID() ChannelID {
+	return c.ChanID
+}

lnwire/update_fail_malformed_htlc.go

@@ -73,3 +73,11 @@ func (c *UpdateFailMalformedHTLC) MaxPayloadLength(uint32) uint32 {
 	// 32 +  8 + 32 + 2
 	return 74
 }
+
+// TargetChanID returns the channel id of the link for which this message is
+// intended.
+//
+// NOTE: Part of lnd.LinkUpdater interface.
+func (c *UpdateFailMalformedHTLC) TargetChanID() ChannelID {
+	return c.ChanID
+}

lnwire/update_fee.go

@@ -68,3 +68,11 @@ func (c *UpdateFee) MaxPayloadLength(uint32) uint32 {
 	// 32 + 4
 	return 36
 }
+
+// TargetChanID returns the channel id of the link for which this message is
+// intended.
+//
+// NOTE: Part of lnd.LinkUpdater interface.
+func (c *UpdateFee) TargetChanID() ChannelID {
+	return c.ChanID
+}

lnwire/update_fulfill_htlc.go

@@ -1,6 +1,8 @@
 package lnwire
 
-import "io"
+import (
+	"io"
+)
 
 // UpdateFulfillHTLC is sent by Alice to Bob when she wishes to settle a
 // particular HTLC referenced by its HTLCKey within a specific active channel
@@ -76,3 +78,11 @@ func (c *UpdateFulfillHTLC) MaxPayloadLength(uint32) uint32 {
 	// 32 + 8 + 32
 	return 72
 }
+
+// TargetChanID returns the channel id of the link for which this message is
+// intended.
+//
+// NOTE: Part of lnd.LinkUpdater interface.
+func (c *UpdateFulfillHTLC) TargetChanID() ChannelID {
+	return c.ChanID
+}