lnd.xprv/lnwire/single_funding_response.go
2016-05-23 13:46:26 -07:00

158 lines
5.2 KiB
Go

package lnwire
import (
"bytes"
"fmt"
"io"
"github.com/roasbeef/btcd/btcec"
)
// 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
// RevocationHash is the initial revocation hash to be used for the
// responders's commitment transaction to derive their revocation public
// key as: P + G*revocationHash, where P is the initiator's channel
// public key.
RevocationHash [20]byte
// 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
// 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
}
// 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)
// Revocation Hash (20)
// Pubkey (32)
// DeliveryPkScript (final delivery)
err := readElements(r,
&c.ChannelID,
&c.RevocationHash,
&c.ChannelDerivationPoint,
&c.DeliveryPkScript)
if err != nil {
return err
}
return nil
}
// NewSingleFundingResponse creates, and returns a new empty
// SingleFundingResponse.
func NewSingleFundingResponse() *SingleFundingResponse {
return &SingleFundingResponse{}
}
// 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)
// Revocation Hash (20)
// Channel Derivation Point (32)
// DeliveryPkScript (final delivery)
err := writeElements(w,
c.ChannelID,
c.RevocationHash,
c.ChannelDerivationPoint,
c.DeliveryPkScript)
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 + 20 + 32 + 25 = 85
//
// This is part of the lnwire.Message interface.
func (c *SingleFundingResponse) MaxPayloadLength(uint32) uint32 {
return 85
}
// 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 {
var zeroHash [20]byte
if bytes.Equal(zeroHash[:], c.RevocationHash[:]) {
return fmt.Errorf("revocation has must be non-zero")
}
// 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.")
}
// We're good!
return nil
}
// String returns the string representation of the SingleFundingResponse.
//
// This is part of the lnwire.Message interface.
func (c *SingleFundingResponse) String() string {
var serializedPubkey []byte
if &c.ChannelDerivationPoint != nil && c.ChannelDerivationPoint.X != nil {
serializedPubkey = c.ChannelDerivationPoint.SerializeCompressed()
}
return fmt.Sprintf("\n--- Begin SingleFundingResponse ---\n") +
fmt.Sprintf("ChannelID:\t\t\t%d\n", c.ChannelID) +
fmt.Sprintf("RevocationHash\t\t\t%x\n", c.RevocationHash) +
fmt.Sprintf("ChannelDerivationPoint\t\t\t\t%x\n", serializedPubkey) +
fmt.Sprintf("DeliveryPkScript\t\t%x\n", c.DeliveryPkScript) +
fmt.Sprintf("--- End SingleFundingResponse ---\n")
}