package lnwire import ( "fmt" "io" "github.com/roasbeef/btcd/btcec" "github.com/roasbeef/btcutil" ) // SingleFundingResponse is the message Bob sends to Alice after she initiates // the single funder channel workflow via a SingleFundingRequest message. Once // Alice receives Bob's reponse, then she has all the items neccessary to // construct the funding transaction, and both commitment transactions. type SingleFundingResponse struct { // ChannelID serves to uniquely identify the future channel created by // the initiated single funder workflow. ChannelID uint64 // ChannelDerivationPoint is an secp256k1 point which will be used to // derive the public key the responder will use for the half of the // 2-of-2 multi-sig. Using the channel derivation point (CDP), and the // responder's identity public key (A), the channel public key is // computed as: C = A + CDP. In order to be valid all CDP's MUST have // an odd y-coordinate. ChannelDerivationPoint *btcec.PublicKey // CommitmentKey is key the responder to the funding workflow wishes to // use within their versino of the commitment transaction for any // delayed (CSV) or immediate outputs to them. CommitmentKey *btcec.PublicKey // RevocationKey is the initial key to be used for the revocation // clause within the self-output of the responder's commitment // transaction. Once an initial new state is created, the responder // will send a preimage which will allow the initiator to sweep the // responder's funds if the violate the contract. RevocationKey *btcec.PublicKey // CsvDelay is the number of blocks to use for the relative time lock // in the pay-to-self output of both commitment transactions. CsvDelay uint32 // DeliveryPkScript defines the public key script that the initiator // would like to use to receive their balance in the case of a // cooperative close. Only the following script templates are // supported: P2PKH, P2WKH, P2SH, and P2WSH. DeliveryPkScript PkScript // DustLimit is the threshold below which no HTLC output should be // generated for remote commitment transaction; ie. HTLCs below // this amount are not enforceable onchain for their point of view. DustLimit btcutil.Amount } // NewSingleFundingResponse creates, and returns a new empty // SingleFundingResponse. func NewSingleFundingResponse(chanID uint64, rk, ck, cdp *btcec.PublicKey, delay uint32, deliveryScript PkScript, dustLimit btcutil.Amount) *SingleFundingResponse { return &SingleFundingResponse{ ChannelID: chanID, ChannelDerivationPoint: cdp, CommitmentKey: ck, RevocationKey: rk, CsvDelay: delay, DeliveryPkScript: deliveryScript, DustLimit: dustLimit, } } // A compile time check to ensure SingleFundingResponse implements the // lnwire.Message interface. var _ Message = (*SingleFundingResponse)(nil) // Decode deserializes the serialized SingleFundingResponse stored in the passed // io.Reader into the target SingleFundingResponse using the deserialization // rules defined by the passed protocol version. // // This is part of the lnwire.Message interface. func (c *SingleFundingResponse) Decode(r io.Reader, pver uint32) error { // ChannelID (8) // ChannelDerivationPoint (33) // CommitmentKey (33) // RevocationKey (33) // CsvDelay (4) // DeliveryPkScript (final delivery) // DustLimit (8) err := readElements(r, &c.ChannelID, &c.ChannelDerivationPoint, &c.CommitmentKey, &c.RevocationKey, &c.CsvDelay, &c.DeliveryPkScript, &c.DustLimit) if err != nil { return err } return nil } // Encode serializes the target SingleFundingResponse into the passed io.Writer // implementation. Serialization will observe the rules defined by the passed // protocol version. // // This is part of the lnwire.Message interface. func (c *SingleFundingResponse) Encode(w io.Writer, pver uint32) error { // ChannelID (8) // ChannelDerivationPoint (33) // CommitmentKey (33) // RevocationKey (33) // CsvDelay (4) // DeliveryPkScript (final delivery) // DustLimit (8) err := writeElements(w, c.ChannelID, c.ChannelDerivationPoint, c.CommitmentKey, c.RevocationKey, c.CsvDelay, c.DeliveryPkScript, c.DustLimit) if err != nil { return err } return nil } // Command returns the uint32 code which uniquely identifies this message as a // SingleFundingRequest on the wire. // // This is part of the lnwire.Message interface. func (c *SingleFundingResponse) Command() uint32 { return CmdSingleFundingResponse } // MaxPayloadLength returns the maximum allowed payload length for a // SingleFundingResponse. This is calculated by summing the max length of all // the fields within a SingleFundingResponse. To enforce a maximum // DeliveryPkScript size, the size of a P2PKH public key script is used. // Therefore, the final breakdown is: 8 + (33 * 3) + 8 + 25 + 8 // // This is part of the lnwire.Message interface. func (c *SingleFundingResponse) MaxPayloadLength(uint32) uint32 { return 148 } // Validate examines each populated field within the SingleFundingResponse for // field sanity. For example, all fields MUST NOT be negative, and all pkScripts // must belong to the allowed set of public key scripts. // // This is part of the lnwire.Message interface. func (c *SingleFundingResponse) Validate() error { // The channel derivation point must be non-nil, and have an odd // y-coordinate. if c.ChannelDerivationPoint == nil { return fmt.Errorf("The channel derivation point must be non-nil") } //if c.ChannelDerivationPoint.Y.Bit(0) != 1 { // return fmt.Errorf("The channel derivation point must have an odd " + // "y-coordinate") //} // The delivery pkScript must be amongst the supported script // templates. if !isValidPkScript(c.DeliveryPkScript) { return fmt.Errorf("Valid delivery public key scripts MUST be: " + "P2PKH, P2WKH, P2SH, or P2WSH.") } if c.DustLimit <= 0 { return fmt.Errorf("Dust limit shouldn't be below or equal to " + "zero.") } // We're good! return nil }