lnwire: add update_fee message type.

lnwire/update_fee.go

@@ -0,0 +1,69 @@
+package lnwire
+
+import (
+	"io"
+
+	"github.com/roasbeef/btcutil"
+)
+
+// UpdateFee is the message the channel initiator sends to the other peer if
+// the channel commitment fee needs to be updated.
+type UpdateFee struct {
+	// ChanID is the channel that this UpdateFee is meant for.
+	ChanID ChannelID
+
+	// FeePerKw is the fee-per-kw on commit transactions that the sender of
+	// this message wants to use for this channel.
+	FeePerKw btcutil.Amount
+}
+
+// NewUpdateFee creates a new UpdateFee message.
+func NewUpdateFee(chanID ChannelID, feePerKw btcutil.Amount) *UpdateFee {
+	return &UpdateFee{
+		ChanID:   chanID,
+		FeePerKw: feePerKw,
+	}
+}
+
+// A compile time check to ensure UpdateFee implements the lnwire.Message
+// interface.
+var _ Message = (*UpdateFee)(nil)
+
+// Decode deserializes a serialized UpdateFee message stored in the
+// passed io.Reader observing the specified protocol version.
+//
+// This is part of the lnwire.Message interface.
+func (c *UpdateFee) Decode(r io.Reader, pver uint32) error {
+	return readElements(r,
+		&c.ChanID,
+		&c.FeePerKw,
+	)
+}
+
+// Encode serializes the target UpdateFee into the passed io.Writer
+// observing the protocol version specified.
+//
+// This is part of the lnwire.Message interface.
+func (c *UpdateFee) Encode(w io.Writer, pver uint32) error {
+	return writeElements(w,
+		c.ChanID,
+		c.FeePerKw,
+	)
+}
+
+// MsgType returns the integer uniquely identifying this message type on the
+// wire.
+//
+// This is part of the lnwire.Message interface.
+func (c *UpdateFee) MsgType() MessageType {
+	return MsgUpdateFee
+}
+
+// MaxPayloadLength returns the maximum allowed payload size for a
+// UpdateFee complete message observing the specified protocol version.
+//
+// This is part of the lnwire.Message interface.
+func (c *UpdateFee) MaxPayloadLength(uint32) uint32 {
+	// 32 + 8
+	return 40
+}