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

	// List of HTLC Keys which are updated from all parties
	UpdatedHTLCKeys []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)
	// c.UpdatedHTLCKeys(8*1000max)
	// RevocationHash(20)
	// Fee(8)
	// RequesterCommitSig(73max+2)
	err := readElements(r,
		&c.ChannelID,
		&c.CommitmentHeight,
		&c.UpdatedHTLCKeys,
		&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.UpdatedHTLCKeys,
		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 8192
}

// 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.RevocationHash,
	// c.UpdatedHTLCKeys,
	// c.Fee,
	// c.CommitSig,
	var serializedSig []byte
	if &c.CommitSig != nil && c.CommitSig.R != nil {
		serializedSig = c.CommitSig.Serialize()
	}
	var items string
	for i := 0; i < len(c.UpdatedHTLCKeys); i++ {
		items += fmt.Sprintf("%d ", c.UpdatedHTLCKeys[i])
	}

	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("UpdatedHTLCKeys:\t%s\n", items) +
		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")
}