package lnwire import ( "bytes" "errors" "fmt" "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 } // String returns the string representation of the target ChannelUpdateAnnouncement. // // This is part of the lnwire.Message interface. func (c *ChannelUpdateAnnouncement) String() string { return fmt.Sprintf("\n--- Begin ChannelUpdateAnnouncement ---\n") + fmt.Sprintf("Signature:\t\t%v\n", c.Signature) + fmt.Sprintf("ChannelID:\t\t%v\n", c.ChannelID.String()) + fmt.Sprintf("Timestamp:\t\t%v\n", c.Timestamp) + fmt.Sprintf("Flags:\t\t%v\n", c.Flags) + fmt.Sprintf("Expiry:\t\t%v\n", c.Expiry) + fmt.Sprintf("HtlcMinimumMstat:\t\t%v\n", c.HtlcMinimumMstat) + fmt.Sprintf("FeeBaseMstat:\t\t%v\n", c.FeeBaseMstat) + fmt.Sprintf("FeeProportionalMillionths:\t\t%v\n", c.FeeProportionalMillionths) + fmt.Sprintf("--- End ChannelUpdateAnnouncement ---\n") } // 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 }