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 the previously sent channel
// announcement and 1 otherwise.
Flags uint16
// TimeLockDelta 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. This value represents the required
// gap between the time locks of the incoming and outgoing HTLC's set
// to this node.
TimeLockDelta uint16
// HtlcMinimumMsat is the minimum HTLC value which will be accepted.
HtlcMinimumMsat uint32
// FeeBaseMstat...
FeeBaseMsat 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.TimeLockDelta == 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.
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func (a *ChannelUpdateAnnouncement) Decode(r io.Reader, pver uint32) error {
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return readElements(r,
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&a.Signature,
&a.ChannelID,
&a.Timestamp,
&a.Flags,
&a.TimeLockDelta,
&a.HtlcMinimumMsat,
&a.FeeBaseMsat,
&a.FeeProportionalMillionths,
)
}
// Encode serializes the target ChannelUpdateAnnouncement into the passed
// io.Writer observing the protocol version specified.
//
// This is part of the lnwire.Message interface.
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func (a *ChannelUpdateAnnouncement) Encode(w io.Writer, pver uint32) error {
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return writeElements(w,
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a.Signature,
a.ChannelID,
a.Timestamp,
a.Flags,
a.TimeLockDelta,
a.HtlcMinimumMsat,
a.FeeBaseMsat,
a.FeeProportionalMillionths,
)
}
// Command returns the integer uniquely identifying this message type on the
// wire.
//
// This is part of the lnwire.Message interface.
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func (a *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.
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func (a *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.
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func (a *ChannelUpdateAnnouncement) DataToSign() ([]byte, error) {
// We should not include the signatures itself.
var w bytes.Buffer
err := writeElements(&w,
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a.ChannelID,
a.Timestamp,
a.Flags,
a.TimeLockDelta,
a.HtlcMinimumMsat,
a.FeeBaseMsat,
a.FeeProportionalMillionths,
)
if err != nil {
return nil, err
}
return w.Bytes(), nil
}