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- package lnwire
- import (
- "bytes"
- "io"
- "github.com/btcsuite/btcd/btcec/v2"
- "github.com/lightningnetwork/lnd/tlv"
- )
- // 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 {
- // ChanID uniquely identifies to which currently active channel this
- // RevokeAndAck applies to.
- ChanID ChannelID
- // Revocation is the preimage to the revocation hash of the now prior
- // commitment transaction.
- Revocation [32]byte
- // NextRevocationKey is the next commitment point which should be used
- // for the next commitment transaction the remote peer creates for us.
- // This, in conjunction with revocation base point will be used to
- // create the proper revocation key used within the commitment
- // transaction.
- NextRevocationKey *btcec.PublicKey
- // LocalNonce is the next _local_ nonce for the sending party. This
- // allows the receiving party to propose a new commitment using their
- // remote nonce and the sender's local nonce.
- LocalNonce OptMusig2NonceTLV
- // 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
- }
- // NewRevokeAndAck creates a new RevokeAndAck message.
- func NewRevokeAndAck() *RevokeAndAck {
- return &RevokeAndAck{
- ExtraData: make([]byte, 0),
- }
- }
- // 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 {
- err := ReadElements(r,
- &c.ChanID,
- c.Revocation[:],
- &c.NextRevocationKey,
- )
- if err != nil {
- return err
- }
- var tlvRecords ExtraOpaqueData
- if err := ReadElements(r, &tlvRecords); err != nil {
- return err
- }
- localNonce := c.LocalNonce.Zero()
- typeMap, err := tlvRecords.ExtractRecords(&localNonce)
- if err != nil {
- return err
- }
- // Set the corresponding TLV types if they were included in the stream.
- if val, ok := typeMap[c.LocalNonce.TlvType()]; ok && val == nil {
- c.LocalNonce = tlv.SomeRecordT(localNonce)
- }
- if len(tlvRecords) != 0 {
- c.ExtraData = tlvRecords
- }
- 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 *bytes.Buffer, pver uint32) error {
- recordProducers := make([]tlv.RecordProducer, 0, 1)
- c.LocalNonce.WhenSome(func(localNonce Musig2NonceTLV) {
- recordProducers = append(recordProducers, &localNonce)
- })
- err := EncodeMessageExtraData(&c.ExtraData, recordProducers...)
- if err != nil {
- return err
- }
- if err := WriteChannelID(w, c.ChanID); err != nil {
- return err
- }
- if err := WriteBytes(w, c.Revocation[:]); err != nil {
- return err
- }
- if err := WritePublicKey(w, c.NextRevocationKey); err != nil {
- return err
- }
- return WriteBytes(w, c.ExtraData)
- }
- // MsgType returns the integer uniquely identifying this message type on the
- // wire.
- //
- // This is part of the lnwire.Message interface.
- func (c *RevokeAndAck) MsgType() MessageType {
- return MsgRevokeAndAck
- }
- // TargetChanID returns the channel id of the link for which this message is
- // intended.
- //
- // NOTE: Part of peer.LinkUpdater interface.
- func (c *RevokeAndAck) TargetChanID() ChannelID {
- return c.ChanID
- }
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