github.com/decred/dcrlnd@v0.7.6/channeldb/migration/lnwire21/revoke_and_ack.go (about)

     1  package lnwire
     2  
     3  import (
     4  	"io"
     5  
     6  	"github.com/decred/dcrd/dcrec/secp256k1/v4"
     7  )
     8  
     9  // RevokeAndAck is sent by either side once a CommitSig message has been
    10  // received, and validated. This message serves to revoke the prior commitment
    11  // transaction, which was the most up to date version until a CommitSig message
    12  // referencing the specified ChannelPoint was received.  Additionally, this
    13  // message also piggyback's the next revocation hash that Alice should use when
    14  // constructing the Bob's version of the next commitment transaction (which
    15  // would be done before sending a CommitSig message).  This piggybacking allows
    16  // Alice to send the next CommitSig message modifying Bob's commitment
    17  // transaction without first asking for a revocation hash initially.
    18  type RevokeAndAck struct {
    19  	// ChanID uniquely identifies to which currently active channel this
    20  	// RevokeAndAck applies to.
    21  	ChanID ChannelID
    22  
    23  	// Revocation is the preimage to the revocation hash of the now prior
    24  	// commitment transaction.
    25  	Revocation [32]byte
    26  
    27  	// NextRevocationKey is the next commitment point which should be used
    28  	// for the next commitment transaction the remote peer creates for us.
    29  	// This, in conjunction with revocation base point will be used to
    30  	// create the proper revocation key used within the commitment
    31  	// transaction.
    32  	NextRevocationKey *secp256k1.PublicKey
    33  }
    34  
    35  // NewRevokeAndAck creates a new RevokeAndAck message.
    36  func NewRevokeAndAck() *RevokeAndAck {
    37  	return &RevokeAndAck{}
    38  }
    39  
    40  // A compile time check to ensure RevokeAndAck implements the lnwire.Message
    41  // interface.
    42  var _ Message = (*RevokeAndAck)(nil)
    43  
    44  // Decode deserializes a serialized RevokeAndAck message stored in the
    45  // passed io.Reader observing the specified protocol version.
    46  //
    47  // This is part of the lnwire.Message interface.
    48  func (c *RevokeAndAck) Decode(r io.Reader, pver uint32) error {
    49  	return ReadElements(r,
    50  		&c.ChanID,
    51  		c.Revocation[:],
    52  		&c.NextRevocationKey,
    53  	)
    54  }
    55  
    56  // Encode serializes the target RevokeAndAck into the passed io.Writer
    57  // observing the protocol version specified.
    58  //
    59  // This is part of the lnwire.Message interface.
    60  func (c *RevokeAndAck) Encode(w io.Writer, pver uint32) error {
    61  	return WriteElements(w,
    62  		c.ChanID,
    63  		c.Revocation[:],
    64  		c.NextRevocationKey,
    65  	)
    66  }
    67  
    68  // MsgType returns the integer uniquely identifying this message type on the
    69  // wire.
    70  //
    71  // This is part of the lnwire.Message interface.
    72  func (c *RevokeAndAck) MsgType() MessageType {
    73  	return MsgRevokeAndAck
    74  }
    75  
    76  // MaxPayloadLength returns the maximum allowed payload size for a RevokeAndAck
    77  // complete message observing the specified protocol version.
    78  //
    79  // This is part of the lnwire.Message interface.
    80  func (c *RevokeAndAck) MaxPayloadLength(uint32) uint32 {
    81  	// 32 + 32 + 33
    82  	return 97
    83  }
    84  
    85  // TargetChanID returns the channel id of the link for which this message is
    86  // intended.
    87  //
    88  // NOTE: Part of peer.LinkUpdater interface.
    89  func (c *RevokeAndAck) TargetChanID() ChannelID {
    90  	return c.ChanID
    91  }