github.com/decred/dcrlnd@v0.7.6/lnwire/commit_sig.go (about)

     1  package lnwire
     2  
     3  import (
     4  	"bytes"
     5  	"io"
     6  )
     7  
     8  // CommitSig is sent by either side to stage any pending HTLC's in the
     9  // receiver's pending set into a new commitment state. Implicitly, the new
    10  // commitment transaction constructed which has been signed by CommitSig
    11  // includes all HTLC's in the remote node's pending set. A CommitSig message
    12  // may be sent after a series of UpdateAddHTLC/UpdateFulfillHTLC messages in
    13  // order to batch add several HTLC's with a single signature covering all
    14  // implicitly accepted HTLC's.
    15  type CommitSig struct {
    16  	// ChanID uniquely identifies to which currently active channel this
    17  	// CommitSig applies to.
    18  	ChanID ChannelID
    19  
    20  	// CommitSig is Alice's signature for Bob's new commitment transaction.
    21  	// Alice is able to send this signature without requesting any
    22  	// additional data due to the piggybacking of Bob's next revocation
    23  	// hash in his prior RevokeAndAck message, as well as the canonical
    24  	// ordering used for all inputs/outputs within commitment transactions.
    25  	// If initiating a new commitment state, this signature should ONLY
    26  	// cover all of the sending party's pending log updates, and the log
    27  	// updates of the remote party that have been ACK'd.
    28  	CommitSig Sig
    29  
    30  	// HtlcSigs is a signature for each relevant HTLC output within the
    31  	// created commitment. The order of the signatures is expected to be
    32  	// identical to the placement of the HTLC's within the BIP 69 sorted
    33  	// commitment transaction. For each outgoing HTLC (from the PoV of the
    34  	// sender of this message), a signature for an HTLC timeout transaction
    35  	// should be signed, for each incoming HTLC the HTLC timeout
    36  	// transaction should be signed.
    37  	HtlcSigs []Sig
    38  
    39  	// ExtraData is the set of data that was appended to this message to
    40  	// fill out the full maximum transport message size. These fields can
    41  	// be used to specify optional data such as custom TLV fields.
    42  	ExtraData ExtraOpaqueData
    43  }
    44  
    45  // NewCommitSig creates a new empty CommitSig message.
    46  func NewCommitSig() *CommitSig {
    47  	return &CommitSig{
    48  		ExtraData: make([]byte, 0),
    49  	}
    50  }
    51  
    52  // A compile time check to ensure CommitSig implements the lnwire.Message
    53  // interface.
    54  var _ Message = (*CommitSig)(nil)
    55  
    56  // Decode deserializes a serialized CommitSig message stored in the
    57  // passed io.Reader observing the specified protocol version.
    58  //
    59  // This is part of the lnwire.Message interface.
    60  func (c *CommitSig) Decode(r io.Reader, pver uint32) error {
    61  	return ReadElements(r,
    62  		&c.ChanID,
    63  		&c.CommitSig,
    64  		&c.HtlcSigs,
    65  		&c.ExtraData,
    66  	)
    67  }
    68  
    69  // Encode serializes the target CommitSig into the passed io.Writer
    70  // observing the protocol version specified.
    71  //
    72  // This is part of the lnwire.Message interface.
    73  func (c *CommitSig) Encode(w *bytes.Buffer, pver uint32) error {
    74  	if err := WriteChannelID(w, c.ChanID); err != nil {
    75  		return err
    76  	}
    77  
    78  	if err := WriteSig(w, c.CommitSig); err != nil {
    79  		return err
    80  	}
    81  
    82  	if err := WriteSigs(w, c.HtlcSigs); err != nil {
    83  		return err
    84  	}
    85  
    86  	return WriteBytes(w, c.ExtraData)
    87  }
    88  
    89  // MsgType returns the integer uniquely identifying this message type on the
    90  // wire.
    91  //
    92  // This is part of the lnwire.Message interface.
    93  func (c *CommitSig) MsgType() MessageType {
    94  	return MsgCommitSig
    95  }
    96  
    97  // TargetChanID returns the channel id of the link for which this message is
    98  // intended.
    99  //
   100  // NOTE: Part of peer.LinkUpdater interface.
   101  func (c *CommitSig) TargetChanID() ChannelID {
   102  	return c.ChanID
   103  }