package lnwire import ( "bytes" "io" "github.com/roasbeef/btcd/btcec" ) // ChannelUpdate 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 ChannelUpdate struct { // Signature is used to validate the announced data and prove the // ownership of node id. Signature *btcec.Signature // ShortChannelID is the unique description of the funding transaction. ShortChannelID ShortChannelID // 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 ChannelUpdate implements the lnwire.Message // interface. var _ Message = (*ChannelUpdate)(nil) // Decode deserializes a serialized ChannelUpdate stored in the passed // io.Reader observing the specified protocol version. // // This is part of the lnwire.Message interface. func (a *ChannelUpdate) Decode(r io.Reader, pver uint32) error { return readElements(r, &a.Signature, &a.ShortChannelID, &a.Timestamp, &a.Flags, &a.TimeLockDelta, &a.HtlcMinimumMsat, &a.FeeBaseMsat, &a.FeeProportionalMillionths, ) } // Encode serializes the target ChannelUpdate into the passed io.Writer // observing the protocol version specified. // // This is part of the lnwire.Message interface. func (a *ChannelUpdate) Encode(w io.Writer, pver uint32) error { return writeElements(w, a.Signature, a.ShortChannelID, a.Timestamp, a.Flags, a.TimeLockDelta, a.HtlcMinimumMsat, a.FeeBaseMsat, a.FeeProportionalMillionths, ) } // MsgType returns the integer uniquely identifying this message type on the // wire. // // This is part of the lnwire.Message interface. func (a *ChannelUpdate) MsgType() MessageType { return MsgChannelUpdate } // MaxPayloadLength returns the maximum allowed payload size for this message // observing the specified protocol version. // // This is part of the lnwire.Message interface. func (a *ChannelUpdate) MaxPayloadLength(pver uint32) uint32 { var length uint32 // Signature - 64 bytes length += 64 // ShortChannelID - 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 (a *ChannelUpdate) DataToSign() ([]byte, error) { // We should not include the signatures itself. var w bytes.Buffer err := writeElements(&w, a.ShortChannelID, a.Timestamp, a.Flags, a.TimeLockDelta, a.HtlcMinimumMsat, a.FeeBaseMsat, a.FeeProportionalMillionths, ) if err != nil { return nil, err } return w.Bytes(), nil }