lnd.xprv/lnwire/revoke_and_ack.go
2017-03-13 16:30:23 -07:00

111 lines
3.7 KiB
Go

package lnwire
import (
"io"
"github.com/roasbeef/btcd/btcec"
"github.com/roasbeef/btcd/wire"
)
// RevokeAndAck is sent by either side once a CommitSig message has been
// received, and validated. This message serves to revoke the prior commitment
// transaction, which was the most up to date version until a CommitSig message
// referencing the specified ChannelPoint was received. Additionally, this
// message also piggyback's the next revocation hash that Alice should use when
// constructing the Bob's version of the next commitment transaction (which
// would be done before sending a CommitSig message). This piggybacking allows
// Alice to send the next CommitSig message modifying Bob's commitment
// transaction without first asking for a revocation hash initially.
type RevokeAndAck struct {
// ChannelPoint uniquely identifies to which currently active channel
// this RevokeAndAck applies to.
ChannelPoint wire.OutPoint
// Revocation is the preimage to the revocation hash of the now prior
// commitment transaction.
//
// If the received revocation is the all zeroes hash ('0' * 32), then
// this RevokeAndAck is being sent in order to build up the sender's
// initial revocation window (IRW). In this case, the RevokeAndAck
// should be added to the receiver's queue of unused revocations to be
// used to construct future commitment transactions.
Revocation [32]byte
// NextRevocationKey is the next revocation key which should be added
// to the queue of unused revocation keys for the remote peer. This key
// will be used within the revocation clause for any new commitment
// transactions created for the remote peer.
NextRevocationKey *btcec.PublicKey
// NextRevocationHash is the next revocation hash which should be added
// to the queue on unused revocation hashes for the remote peer. This
// revocation hash will be used within any HTLCs included within this
// next commitment transaction.
NextRevocationHash [32]byte
}
// NewRevokeAndAck creates a new RevokeAndAck message.
func NewRevokeAndAck() *RevokeAndAck {
return &RevokeAndAck{}
}
// A compile time check to ensure RevokeAndAck implements the lnwire.Message
// interface.
var _ Message = (*RevokeAndAck)(nil)
// Decode deserializes a serialized RevokeAndAck message stored in the
// passed io.Reader observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
func (c *RevokeAndAck) Decode(r io.Reader, pver uint32) error {
// ChannelPoint (8)
// Revocation (32)
// NextRevocationKey (33)
// NextRevocationHash (32)
return readElements(r,
&c.ChannelPoint,
c.Revocation[:],
&c.NextRevocationKey,
c.NextRevocationHash[:],
)
}
// Encode serializes the target RevokeAndAck into the passed io.Writer
// observing the protocol version specified.
//
// This is part of the lnwire.Message interface.
func (c *RevokeAndAck) Encode(w io.Writer, pver uint32) error {
return writeElements(w,
c.ChannelPoint,
c.Revocation[:],
c.NextRevocationKey,
c.NextRevocationHash[:],
)
}
// Command returns the integer uniquely identifying this message type on the
// wire.
//
// This is part of the lnwire.Message interface.
func (c *RevokeAndAck) Command() uint32 {
return CmdRevokeAndAck
}
// MaxPayloadLength returns the maximum allowed payload size for a
// RevokeAndAck complete message observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
func (c *RevokeAndAck) MaxPayloadLength(uint32) uint32 {
// 36 + 32 + 33 + 32
return 133
}
// Validate performs any necessary sanity checks to ensure all fields present
// on the RevokeAndAck are valid.
//
// This is part of the lnwire.Message interface.
func (c *RevokeAndAck) Validate() error {
// We're good!
return nil
}