lnd.xprv/lnwire/commit_signature.go

package lnwire

import (
	"fmt"
	"github.com/btcsuite/btcd/btcec"
	"github.com/btcsuite/btcutil"
	"io"
)

//Multiple Clearing Requests are possible by putting this inside an array of
//clearing requests
type CommitSignature struct {
	//We can use a different data type for this if necessary...
	ChannelID uint64

	//Height of the commitment
	//You should have the most recent commitment height stored locally
	//This should be validated!
	//This is used for shachain.
	//Each party increments their own CommitmentHeight, they can differ for
	//each part of the Commitment.
	CommitmentHeight uint64

	//The last staging included by both parties
	//Basically, the state is updated to this point on both parties'
	//staging
	//Staging inclusion is in order.
	CommitterLastStaging uint64
	ReceiverLastStaging  uint64

	//Hash of the revocation to use
	RevocationHash [20]byte

	//Total miners' fee that was used
	Fee btcutil.Amount

	//Signature for the new Commitment
	CommitSig *btcec.Signature //Requester's Commitment
}

func (c *CommitSignature) Decode(r io.Reader, pver uint32) error {
	//ChannelID(8)
	//CommitmentHeight(8)
	//CommiterLastStaging(8)
	//ReceiverLastStaging(8)
	//RevocationHash(20)
	//Fee(8)
	//RequesterCommitSig(73max+2)
	err := readElements(r,
		&c.ChannelID,
		&c.CommitmentHeight,
		&c.CommitterLastStaging,
		&c.ReceiverLastStaging,
		&c.RevocationHash,
		&c.Fee,
		&c.CommitSig,
	)
	if err != nil {
		return err
	}

	return nil
}

//Creates a new CommitSignature
func NewCommitSignature() *CommitSignature {
	return &CommitSignature{}
}

//Serializes the item from the CommitSignature struct
//Writes the data to w
func (c *CommitSignature) Encode(w io.Writer, pver uint32) error {
	err := writeElements(w,
		c.ChannelID,
		c.CommitmentHeight,
		c.CommitterLastStaging,
		c.ReceiverLastStaging,
		c.RevocationHash,
		c.Fee,
		c.CommitSig,
	)
	if err != nil {
		return err
	}

	return nil
}

func (c *CommitSignature) Command() uint32 {
	return CmdCommitSignature
}

func (c *CommitSignature) MaxPayloadLength(uint32) uint32 {
	return 135
}

//Makes sure the struct data is valid (e.g. no negatives or invalid pkscripts)
func (c *CommitSignature) Validate() error {
	if c.Fee < 0 {
		//While fees can be negative, it's too confusing to allow
		//negative payments. Maybe for some wallets, but not this one!
		return fmt.Errorf("Amount paid cannot be negative.")
	}
	//We're good!
	return nil
}

func (c *CommitSignature) String() string {
	//c.ChannelID,
	//c.CommitmentHeight,
	//c.CommitterLastStaging,
	//c.ReceiverLastStaging,
	//c.RevocationHash,
	//c.Fee,
	//c.CommitSig,
	var serializedSig []byte
	if &c.CommitSig != nil && c.CommitSig.R != nil {
		serializedSig = c.CommitSig.Serialize()
	}

	return fmt.Sprintf("\n--- Begin CommitSignature ---\n") +
		fmt.Sprintf("ChannelID:\t\t%d\n", c.ChannelID) +
		fmt.Sprintf("CommitmentHeight:\t%d\n", c.CommitmentHeight) +
		fmt.Sprintf("CommitterLastStaging:\t%d\n", c.CommitterLastStaging) +
		fmt.Sprintf("ReceiverLastStaging:\t%d\n", c.ReceiverLastStaging) +
		fmt.Sprintf("RevocationHash:\t\t%x\n", c.RevocationHash) +
		fmt.Sprintf("Fee:\t\t\t%s\n", c.Fee.String()) +
		fmt.Sprintf("CommitSig:\t\t%x\n", serializedSig) +
		fmt.Sprintf("--- End CommitSignature ---\n")
}