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) err := readElements(r, &c.ChannelPoint, c.Revocation[:], &c.NextRevocationKey, c.NextRevocationHash[:], ) if err != nil { return err } return nil } // 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 { err := writeElements(w, c.ChannelPoint, c.Revocation[:], c.NextRevocationKey, c.NextRevocationHash[:], ) 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 *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 }