lnd.xprv/lnwire/channel_update_announcement.go

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package lnwire
import (
"bytes"
"errors"
"io"
"github.com/roasbeef/btcd/btcec"
)
// ChannelUpdateAnnouncement message is used after channel has been initially
// announced. Each side independently announces its fees and minimum expiry for
// HTLCs and other parameters. Also this message is used to redeclare initially
// setted channel parameters.
type ChannelUpdateAnnouncement struct {
// Signature is used to validate the announced data and prove the
// ownership of node id.
Signature *btcec.Signature
// ChannelID is the unique description of the funding transaction.
ChannelID ChannelID
// Timestamp allows ordering in the case of multiple announcements.
// We should ignore the message if timestamp is not greater than
// the last-received.
Timestamp uint32
// Flags least-significant bit must be set to 0 if the creating node
// corresponds to the first node in previously sent channel
// announcement and 1 otherwise.
Flags uint16
// Expiry is the minimum number of blocks this node requires to be
// added to the expiry of HTLCs. This is a security parameter determined
// by the node operator.
Expiry uint16
// HtlcMinimumMstat is the minimum HTLC value which will be accepted.
HtlcMinimumMstat uint32
// FeeBaseMstat...
FeeBaseMstat uint32
// FeeProportionalMillionths...
FeeProportionalMillionths uint32
}
// A compile time check to ensure ChannelUpdateAnnouncement implements the
// lnwire.Message interface.
var _ Message = (*ChannelUpdateAnnouncement)(nil)
// Validate performs any necessary sanity checks to ensure all fields present
// on the ChannelUpdateAnnouncement are valid.
//
// This is part of the lnwire.Message interface.
func (a *ChannelUpdateAnnouncement) Validate() error {
// NOTE: As far as we don't have the node id (public key) in this
// message, we can't validate the signature on this stage, it should
// be validated latter - in discovery service handler.
if a.Expiry == 0 {
return errors.New("expiry should be greater then zero")
}
return nil
}
// Decode deserializes a serialized ChannelUpdateAnnouncement stored in the
// passed io.Reader observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
func (c *ChannelUpdateAnnouncement) Decode(r io.Reader, pver uint32) error {
err := readElements(r,
&c.Signature,
&c.ChannelID,
&c.Timestamp,
&c.Flags,
&c.Expiry,
&c.HtlcMinimumMstat,
&c.FeeBaseMstat,
&c.FeeProportionalMillionths,
)
if err != nil {
return err
}
return nil
}
// Encode serializes the target ChannelUpdateAnnouncement into the passed
// io.Writer observing the protocol version specified.
//
// This is part of the lnwire.Message interface.
func (c *ChannelUpdateAnnouncement) Encode(w io.Writer, pver uint32) error {
err := writeElements(w,
c.Signature,
c.ChannelID,
c.Timestamp,
c.Flags,
c.Expiry,
c.HtlcMinimumMstat,
c.FeeBaseMstat,
c.FeeProportionalMillionths,
)
if err != nil {
return err
}
return nil
}
// Command returns the integer uniquely identifying this message type on the
// wire.
//
// This is part of the lnwire.Message interface.
func (c *ChannelUpdateAnnouncement) Command() uint32 {
return CmdChannelUpdateAnnoucmentMessage
}
// MaxPayloadLength returns the maximum allowed payload size for this message
// observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
func (c *ChannelUpdateAnnouncement) MaxPayloadLength(pver uint32) uint32 {
var length uint32
// Signature - 64 bytes
length += 64
// ChannelID - 8 bytes
length += 8
// Timestamp - 4 bytes
length += 4
// Flags - 2 bytes
length += 2
// Expiry - 2 bytes
length += 2
// HtlcMinimumMstat - 4 bytes
length += 4
// FeeBaseMstat - 4 bytes
length += 4
// FeeProportionalMillionths - 4 bytes
length += 4
return length
}
// DataToSign is used to retrieve part of the announcement message which
// should be signed.
func (c *ChannelUpdateAnnouncement) DataToSign() ([]byte, error) {
// We should not include the signatures itself.
var w bytes.Buffer
err := writeElements(&w,
c.ChannelID,
c.Timestamp,
c.Flags,
c.Expiry,
c.HtlcMinimumMstat,
c.FeeBaseMstat,
c.FeeProportionalMillionths,
)
if err != nil {
return nil, err
}
return w.Bytes(), nil
}