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- package lnwire
- import (
- "bytes"
- "io"
- "github.com/lightningnetwork/lnd/tlv"
- )
- // CommitSig is sent by either side to stage any pending HTLC's in the
- // receiver's pending set into a new commitment state. Implicitly, the new
- // commitment transaction constructed which has been signed by CommitSig
- // includes all HTLC's in the remote node's pending set. A CommitSig message
- // may be sent after a series of UpdateAddHTLC/UpdateFulfillHTLC messages in
- // order to batch add several HTLC's with a single signature covering all
- // implicitly accepted HTLC's.
- type CommitSig struct {
- // ChanID uniquely identifies to which currently active channel this
- // CommitSig applies to.
- ChanID ChannelID
- // CommitSig is Alice's signature for Bob's new commitment transaction.
- // Alice is able to send this signature without requesting any
- // additional data due to the piggybacking of Bob's next revocation
- // hash in his prior RevokeAndAck message, as well as the canonical
- // ordering used for all inputs/outputs within commitment transactions.
- // If initiating a new commitment state, this signature should ONLY
- // cover all of the sending party's pending log updates, and the log
- // updates of the remote party that have been ACK'd.
- CommitSig Sig
- // HtlcSigs is a signature for each relevant HTLC output within the
- // created commitment. The order of the signatures is expected to be
- // identical to the placement of the HTLC's within the BIP 69 sorted
- // commitment transaction. For each outgoing HTLC (from the PoV of the
- // sender of this message), a signature for an HTLC timeout transaction
- // should be signed, for each incoming HTLC the HTLC timeout
- // transaction should be signed.
- HtlcSigs []Sig
- // PartialSig is used to transmit a musig2 extended partial signature
- // that also carries along the public nonce of the signer.
- //
- // NOTE: This field is only populated if a musig2 taproot channel is
- // being signed for. In this case, the above Sig type MUST be blank.
- PartialSig OptPartialSigWithNonceTLV
- // 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
- }
- // NewCommitSig creates a new empty CommitSig message.
- func NewCommitSig() *CommitSig {
- return &CommitSig{
- ExtraData: make([]byte, 0),
- }
- }
- // A compile time check to ensure CommitSig implements the lnwire.Message
- // interface.
- var _ Message = (*CommitSig)(nil)
- // Decode deserializes a serialized CommitSig message stored in the
- // passed io.Reader observing the specified protocol version.
- //
- // This is part of the lnwire.Message interface.
- func (c *CommitSig) Decode(r io.Reader, pver uint32) error {
- err := ReadElements(r,
- &c.ChanID,
- &c.CommitSig,
- &c.HtlcSigs,
- )
- if err != nil {
- return err
- }
- var tlvRecords ExtraOpaqueData
- if err := ReadElements(r, &tlvRecords); err != nil {
- return err
- }
- partialSig := c.PartialSig.Zero()
- typeMap, err := tlvRecords.ExtractRecords(&partialSig)
- if err != nil {
- return err
- }
- // Set the corresponding TLV types if they were included in the stream.
- if val, ok := typeMap[c.PartialSig.TlvType()]; ok && val == nil {
- c.PartialSig = tlv.SomeRecordT(partialSig)
- }
- if len(tlvRecords) != 0 {
- c.ExtraData = tlvRecords
- }
- return nil
- }
- // Encode serializes the target CommitSig into the passed io.Writer
- // observing the protocol version specified.
- //
- // This is part of the lnwire.Message interface.
- func (c *CommitSig) Encode(w *bytes.Buffer, pver uint32) error {
- recordProducers := make([]tlv.RecordProducer, 0, 1)
- c.PartialSig.WhenSome(func(sig PartialSigWithNonceTLV) {
- recordProducers = append(recordProducers, &sig)
- })
- err := EncodeMessageExtraData(&c.ExtraData, recordProducers...)
- if err != nil {
- return err
- }
- if err := WriteChannelID(w, c.ChanID); err != nil {
- return err
- }
- if err := WriteSig(w, c.CommitSig); err != nil {
- return err
- }
- if err := WriteSigs(w, c.HtlcSigs); 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 *CommitSig) MsgType() MessageType {
- return MsgCommitSig
- }
- // TargetChanID returns the channel id of the link for which this message is
- // intended.
- //
- // NOTE: Part of peer.LinkUpdater interface.
- func (c *CommitSig) TargetChanID() ChannelID {
- return c.ChanID
- }
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