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

     1  package lnwire
     2  
     3  import (
     4  	"bytes"
     5  	"io"
     6  
     7  	"github.com/decred/dcrd/dcrec/secp256k1/v4"
     8  )
     9  
    10  // RevokeAndAck is sent by either side once a CommitSig message has been
    11  // received, and validated. This message serves to revoke the prior commitment
    12  // transaction, which was the most up to date version until a CommitSig message
    13  // referencing the specified ChannelPoint was received.  Additionally, this
    14  // message also piggyback's the next revocation hash that Alice should use when
    15  // constructing the Bob's version of the next commitment transaction (which
    16  // would be done before sending a CommitSig message).  This piggybacking allows
    17  // Alice to send the next CommitSig message modifying Bob's commitment
    18  // transaction without first asking for a revocation hash initially.
    19  type RevokeAndAck struct {
    20  	// ChanID uniquely identifies to which currently active channel this
    21  	// RevokeAndAck applies to.
    22  	ChanID ChannelID
    23  
    24  	// Revocation is the preimage to the revocation hash of the now prior
    25  	// commitment transaction.
    26  	Revocation [32]byte
    27  
    28  	// NextRevocationKey is the next commitment point which should be used
    29  	// for the next commitment transaction the remote peer creates for us.
    30  	// This, in conjunction with revocation base point will be used to
    31  	// create the proper revocation key used within the commitment
    32  	// transaction.
    33  	NextRevocationKey *secp256k1.PublicKey
    34  
    35  	// ExtraData is the set of data that was appended to this message to
    36  	// fill out the full maximum transport message size. These fields can
    37  	// be used to specify optional data such as custom TLV fields.
    38  	ExtraData ExtraOpaqueData
    39  }
    40  
    41  // NewRevokeAndAck creates a new RevokeAndAck message.
    42  func NewRevokeAndAck() *RevokeAndAck {
    43  	return &RevokeAndAck{
    44  		ExtraData: make([]byte, 0),
    45  	}
    46  }
    47  
    48  // A compile time check to ensure RevokeAndAck implements the lnwire.Message
    49  // interface.
    50  var _ Message = (*RevokeAndAck)(nil)
    51  
    52  // Decode deserializes a serialized RevokeAndAck message stored in the
    53  // passed io.Reader observing the specified protocol version.
    54  //
    55  // This is part of the lnwire.Message interface.
    56  func (c *RevokeAndAck) Decode(r io.Reader, pver uint32) error {
    57  	return ReadElements(r,
    58  		&c.ChanID,
    59  		c.Revocation[:],
    60  		&c.NextRevocationKey,
    61  		&c.ExtraData,
    62  	)
    63  }
    64  
    65  // Encode serializes the target RevokeAndAck into the passed io.Writer
    66  // observing the protocol version specified.
    67  //
    68  // This is part of the lnwire.Message interface.
    69  func (c *RevokeAndAck) Encode(w *bytes.Buffer, pver uint32) error {
    70  	if err := WriteChannelID(w, c.ChanID); err != nil {
    71  		return err
    72  	}
    73  
    74  	if err := WriteBytes(w, c.Revocation[:]); err != nil {
    75  		return err
    76  	}
    77  
    78  	if err := WritePublicKey(w, c.NextRevocationKey); err != nil {
    79  		return err
    80  	}
    81  
    82  	return WriteBytes(w, c.ExtraData)
    83  }
    84  
    85  // MsgType returns the integer uniquely identifying this message type on the
    86  // wire.
    87  //
    88  // This is part of the lnwire.Message interface.
    89  func (c *RevokeAndAck) MsgType() MessageType {
    90  	return MsgRevokeAndAck
    91  }
    92  
    93  // TargetChanID returns the channel id of the link for which this message is
    94  // intended.
    95  //
    96  // NOTE: Part of peer.LinkUpdater interface.
    97  func (c *RevokeAndAck) TargetChanID() ChannelID {
    98  	return c.ChanID
    99  }