package lnwire import ( "fmt" "io" "github.com/roasbeef/btcd/btcec" "github.com/roasbeef/btcutil" ) // SingleFundingRequest is the message Alice sends to Bob if we should like // to create a channel with Bob where she's the sole provider of funds to the // channel. Single funder channels simplify the initial funding workflow, are // supported by nodes backed by SPV Bitcoin clients, and have a simpler // security models than dual funded channels. // // NOTE: In order to avoid a slow loris like resource exhaustion attack, the // responder of a single funding channel workflow *should not* watch the // blockchain for the funding transaction. Instead, it is the initiator's job // to provide the responder with an SPV proof of funding transaction inclusion // after a sufficient number of confirmations. type SingleFundingRequest struct { // ChannelID serves to uniquely identify the future channel created by // the initiated single funder workflow. ChannelID uint64 // ChannelType represents the type of channel this request would like // to open. At this point, the only supported channels are type 0 // channels, which are channels with regular commitment transactions // utilizing HTLC's for payments. ChannelType uint8 // CoinType represents which blockchain the channel will be opened // using. By default, this field should be set to 0, indicating usage // of the Bitcoin blockchain. CoinType uint64 // FeePerKb is the required number of satoshis per KB that the // requester will pay at all timers, for both the funding transaction // and commitment transaction. This value can later be updated once the // channel is open. FeePerKb btcutil.Amount // FundingAmount is the number of satoshis the the initiator would like // to commit to the channel. FundingAmount btcutil.Amount // 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 // CommitmentKey is key the initiator of 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 // ChannelDerivationPoint is an secp256k1 point which will be used to // derive the public key the initiator will use for the half of the // 2-of-2 multi-sig. Using the channel derivation point (CDP), and the // initiators 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 // 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 our commitment transaction; ie. HTLCs below // this amount are not enforceable onchain from our point view. DustLimit btcutil.Amount // TODO(roasbeef): confirmation depth } // NewSingleFundingRequest creates, and returns a new empty SingleFundingRequest. func NewSingleFundingRequest(chanID uint64, chanType uint8, coinType uint64, fee btcutil.Amount, amt btcutil.Amount, delay uint32, ck, cdp *btcec.PublicKey, deliveryScript PkScript, dustLimit btcutil.Amount) *SingleFundingRequest { return &SingleFundingRequest{ ChannelID: chanID, ChannelType: chanType, CoinType: coinType, FeePerKb: fee, FundingAmount: amt, CsvDelay: delay, CommitmentKey: ck, ChannelDerivationPoint: cdp, DeliveryPkScript: deliveryScript, DustLimit: dustLimit, } } // Decode deserializes the serialized SingleFundingRequest stored in the passed // io.Reader into the target SingleFundingRequest using the deserialization // rules defined by the passed protocol version. // // This is part of the lnwire.Message interface. func (c *SingleFundingRequest) Decode(r io.Reader, pver uint32) error { // ChannelID (8) // ChannelType (1) // CoinType (8) // FeePerKb (8) // PaymentAmount (8) // Delay (4) // Pubkey (33) // Pubkey (33) // DeliveryPkScript (final delivery) // DustLimit (8) err := readElements(r, &c.ChannelID, &c.ChannelType, &c.CoinType, &c.FeePerKb, &c.FundingAmount, &c.CsvDelay, &c.CommitmentKey, &c.ChannelDerivationPoint, &c.DeliveryPkScript, &c.DustLimit) if err != nil { return err } return nil } // Encode serializes the target SingleFundingRequest 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 *SingleFundingRequest) Encode(w io.Writer, pver uint32) error { // ChannelID (8) // ChannelType (1) // CoinType (8) // FeePerKb (8) // PaymentAmount (8) // Delay (4) // Pubkey (33) // Pubkey (33) // DeliveryPkScript (final delivery) // DustLimit (8) err := writeElements(w, c.ChannelID, c.ChannelType, c.CoinType, c.FeePerKb, c.FundingAmount, c.CsvDelay, c.CommitmentKey, c.ChannelDerivationPoint, 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 *SingleFundingRequest) Command() uint32 { return CmdSingleFundingRequest } // MaxPayloadLength returns the maximum allowed payload length for a // SingleFundingRequest. This is calculated by summing the max length of all // the fields within a SingleFundingRequest. To enforce a maximum // DeliveryPkScript size, the size of a P2PKH public key script is used. // Therefore, the final breakdown is: 8 + 1 + 8 + 8 + 8 + 4 + 33 + 33 + 25 + 8 = // 166. // // This is part of the lnwire.Message interface. func (c *SingleFundingRequest) MaxPayloadLength(uint32) uint32 { return 166 } // Validate examines each populated field within the SingleFundingRequest 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 *SingleFundingRequest) Validate() error { // Negative values is are allowed. if c.FeePerKb < 0 { return fmt.Errorf("MinFeePerKb cannot be negative") } if c.FundingAmount < 0 { return fmt.Errorf("FundingAmount cannot be negative") } // The CSV delay MUST be non-zero. if c.CsvDelay == 0 { return fmt.Errorf("Commitment transaction must have non-zero " + "CSV delay") } // 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) { // TODO(roasbeef): move into actual error return fmt.Errorf("Valid delivery public key scripts MUST be: " + "P2PKH, P2WKH, P2SH, or P2WSH.") } if c.DustLimit <= 0 { return fmt.Errorf("Dust limit should be greater than zero.") } // We're good! return nil } // String returns the string representation of the SingleFundingRequest. // // This is part of the lnwire.Message interface. func (c *SingleFundingRequest) String() string { var serializedPubkey []byte if &c.ChannelDerivationPoint != nil && c.ChannelDerivationPoint.X != nil { serializedPubkey = c.ChannelDerivationPoint.SerializeCompressed() } // TODO(roasbeef): remove string methods? return fmt.Sprintf("\n--- Begin SingleFundingRequest ---\n") + fmt.Sprintf("ChannelID:\t\t\t%d\n", c.ChannelID) + fmt.Sprintf("ChannelType:\t\t\t%x\n", c.ChannelType) + fmt.Sprintf("CoinType:\t\t\t%d\n", c.CoinType) + fmt.Sprintf("FeePerKb:\t\t\t%s\n", c.FeePerKb.String()) + fmt.Sprintf("FundingAmount:\t\t\t%s\n", c.FundingAmount.String()) + fmt.Sprintf("CsvDelay:\t\t\t%d\n", c.CsvDelay) + fmt.Sprintf("ChannelDerivationPoint:\t\t\t%x\n", serializedPubkey) + fmt.Sprintf("DeliveryPkScript:\t\t\t%x\n", c.DeliveryPkScript) + fmt.Sprintf("DustLimit:\t\t\t%d\n", c.DustLimit) + fmt.Sprintf("--- End SingleFundingRequest ---\n") }