lnwire: introduce message types for dynamic commitment negotiation

lnwire: add tests for dynamic commitment wire serialization

lnwire/dyn_ack.go

@@ -0,0 +1,53 @@
+package lnwire
+
+import (
+	"bytes"
+	"io"
+)
+
+// DynAck is the message used to accept the parameters of a dynamic commitment
+// negotiation. Additional optional parameters will need to be present depending
+// on the details of the dynamic commitment upgrade.
+type DynAck struct {
+	// ChanID is the ChannelID of the channel that is currently undergoing
+	// a dynamic commitment negotiation
+	ChanID ChannelID
+
+	// ExtraData is the set of data that was appended to this message to
+	// fill out the full maximum transport message size. These fields can
+	// be used to specify optional data such as custom TLV fields.
+	ExtraData ExtraOpaqueData
+}
+
+// A compile time check to ensure DynAck implements the lnwire.Message
+// interface.
+var _ Message = (*DynAck)(nil)
+
+// Encode serializes the target DynAck into the passed io.Writer. Serialization
+// will observe the rules defined by the passed protocol version.
+//
+// This is a part of the lnwire.Message interface.
+func (da *DynAck) Encode(w *bytes.Buffer, _ uint32) error {
+	if err := WriteChannelID(w, da.ChanID); err != nil {
+		return err
+	}
+
+	return WriteBytes(w, da.ExtraData)
+}
+
+// Decode deserializes the serialized DynAck stored in the passed io.Reader into
+// the target DynAck using the deserialization rules defined by the passed
+// protocol version.
+//
+// This is a part of the lnwire.Message interface.
+func (da *DynAck) Decode(r io.Reader, _ uint32) error {
+	return ReadElements(r, &da.ChanID, &da.ExtraData)
+}
+
+// MsgType returns the MessageType code which uniquely identifies this message
+// as a DynAck on the wire.
+//
+// This is part of the lnwire.Message interface.
+func (da *DynAck) MsgType() MessageType {
+	return MsgDynAck
+}