lnd.xprv/lnwire/commit_signature.go
Olaoluwa Osuntokun 913ae259de
lnwire: document commitment+HTLC update msgs
This commit adds some cursory documentation along wit minor field
modifications to all messages which deal with adding HTLC’s, or
updating remote commitment transactions.

The messages for dual funding of channel is left purposefully
undocumented as all initial negotiations will be single funder by
default.

A revamp of the testing infrastructure of lnwire will be committed in
the near future.
2016-05-23 13:54:41 -07:00

122 lines
3.8 KiB
Go

package lnwire
import (
"fmt"
"io"
"github.com/roasbeef/btcd/btcec"
"github.com/roasbeef/btcutil"
)
// CommitSignature is sent by either side to stage any pending HTLC's in the
// reciever's pending set which has not explcitly been rejected via an
// HTLCAddReject message. Implictly, the new commitment transaction constructed
// which has been signed by CommitSig includes all HTLC's in the remote node's
// pending set. A CommitSignature message may be sent after a series of HTLCAdd
// messages in order to batch add several HTLC's with a single signature
// covering all implicitly accepted HTLC's.
type CommitSignature struct {
// ChannelID uniquely identifies to which currently active channel this
// CommitSignature applies to.
ChannelID uint64
// Fee represents the total miner's fee that was used when constructing
// the new commitment transaction.
// TODO(roasbeef): is the above comment correct?
Fee btcutil.Amount
// 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 CommitRevocation message, as well as the cannonical ordering
// used for all inputs/outputs within commitment transactions.
CommitSig *btcec.Signature
}
// Decode deserializes a serialized CommitSignature message stored in the
// passed io.Reader observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
func (c *CommitSignature) Decode(r io.Reader, pver uint32) error {
// ChannelID(8)
// Fee(8)
// RequesterCommitSig(73max+2)
err := readElements(r,
&c.ChannelID,
&c.Fee,
&c.CommitSig,
)
if err != nil {
return err
}
return nil
}
// NewCommitSignature creates a new empty CommitSignature message.
func NewCommitSignature() *CommitSignature {
return &CommitSignature{}
}
// A compile time check to ensure CommitSignature implements the lnwire.Message
// interface.
var _ Message = (*CommitSignature)(nil)
// Encode serializes the target CommitSignature into the passed io.Writer
// observing the protocol version specified.
//
// This is part of the lnwire.Message interface.
func (c *CommitSignature) Encode(w io.Writer, pver uint32) error {
// TODO(roasbeef): make similar modificaiton to all other encode/decode
// messags
return writeElements(w, c.ChannelID, c.Fee, c.CommitSig)
}
// Command returns the integer uniquely identifying this message type on the
// wire.
//
// This is part of the lnwire.Message interface.
func (c *CommitSignature) Command() uint32 {
return CmdCommitSignature
}
// MaxPayloadLength returns the maximum allowed payload size for a
// CommitSignature complete message observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
func (c *CommitSignature) MaxPayloadLength(uint32) uint32 {
// 8 + 8 + 73
return 89
}
// Validate performs any necessary sanity checks to ensure all fields present
// on the CommitSignature are valid.
//
// This is part of the lnwire.Message interface.
func (c *CommitSignature) Validate() error {
if c.Fee < 0 {
// While fees can be negative, it's too confusing to allow
// negative payments. Maybe for some wallets, but not this one!
return fmt.Errorf("Amount paid cannot be negative.")
}
// We're good!
return nil
}
// String returns the string representation of the target CommitSignature.
//
// This is part of the lnwire.Message interface.
func (c *CommitSignature) String() string {
var serializedSig []byte
if c.CommitSig != nil {
serializedSig = c.CommitSig.Serialize()
}
return fmt.Sprintf("\n--- Begin CommitSignature ---\n") +
fmt.Sprintf("ChannelID:\t%d\n", c.ChannelID) +
fmt.Sprintf("Fee:\t\t\t%s\n", c.Fee.String()) +
fmt.Sprintf("CommitSig:\t\t%x\n", serializedSig) +
fmt.Sprintf("--- End CommitSignature ---\n")
}