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channel_announcement.go
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channel_announcement.go
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package lnwire
import (
"bytes"
"io"
"github.com/go-errors/errors"
"github.com/roasbeef/btcd/btcec"
"github.com/roasbeef/btcd/chaincfg/chainhash"
)
// ChannelAnnouncement message is used to announce the existence of a channel
// between two peers in the overlay, which is propagated by the discovery
// service over broadcast handler.
type ChannelAnnouncement struct {
// This signatures are used by nodes in order to create cross
// references between node's channel and node. Requiring both nodes
// to sign indicates they are both willing to route other payments via
// this node.
FirstNodeSig *btcec.Signature
SecondNodeSig *btcec.Signature
// ChannelID is the unique description of the funding transaction.
ChannelID ChannelID
// This signatures are used by nodes in order to create cross
// references between node's channel and node. Requiring the bitcoin
// signatures proves they control the channel.
FirstBitcoinSig *btcec.Signature
SecondBitcoinSig *btcec.Signature
// The public keys of the two nodes who are operating the channel, such
// that is FirstNodeID the numerically-lesser of the two DER encoded
// keys (ascending numerical order).
FirstNodeID *btcec.PublicKey
SecondNodeID *btcec.PublicKey
// Public keys which corresponds to the keys which was declared in
// multisig funding transaction output.
FirstBitcoinKey *btcec.PublicKey
SecondBitcoinKey *btcec.PublicKey
}
// A compile time check to ensure ChannelAnnouncement implements the
// lnwire.Message interface.
var _ Message = (*ChannelAnnouncement)(nil)
// Validate performs any necessary sanity checks to ensure all fields present
// on the ChannelAnnouncement are valid.
//
// This is part of the lnwire.Message interface.
func (a *ChannelAnnouncement) Validate() error {
// TODO(roasbeef): move validation to discovery service
return nil
var sigHash []byte
sigHash = chainhash.DoubleHashB(a.FirstNodeID.SerializeCompressed())
if !a.FirstBitcoinSig.Verify(sigHash, a.FirstBitcoinKey) {
return errors.New("can't verify first bitcoin signature")
}
sigHash = chainhash.DoubleHashB(a.SecondNodeID.SerializeCompressed())
if !a.SecondBitcoinSig.Verify(sigHash, a.SecondBitcoinKey) {
return errors.New("can't verify second bitcoin signature")
}
data, err := a.DataToSign()
if err != nil {
return err
}
dataHash := chainhash.DoubleHashB(data)
if !a.FirstNodeSig.Verify(dataHash, a.FirstNodeID) {
return errors.New("can't verify data in first node signature")
}
if !a.SecondNodeSig.Verify(dataHash, a.SecondNodeID) {
return errors.New("can't verify data in second node signature")
}
return nil
}
// Decode deserializes a serialized ChannelAnnouncement stored in the passed
// io.Reader observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
func (c *ChannelAnnouncement) Decode(r io.Reader, pver uint32) error {
err := readElements(r,
&c.FirstNodeSig,
&c.SecondNodeSig,
&c.ChannelID,
&c.FirstBitcoinSig,
&c.SecondBitcoinSig,
&c.FirstNodeID,
&c.SecondNodeID,
&c.FirstBitcoinKey,
&c.SecondBitcoinKey,
)
if err != nil {
return err
}
return nil
}
// Encode serializes the target ChannelAnnouncement into the passed io.Writer
// observing the protocol version specified.
//
// This is part of the lnwire.Message interface.
func (c *ChannelAnnouncement) Encode(w io.Writer, pver uint32) error {
err := writeElements(w,
c.FirstNodeSig,
c.SecondNodeSig,
c.ChannelID,
c.FirstBitcoinSig,
c.SecondBitcoinSig,
c.FirstNodeID,
c.SecondNodeID,
c.FirstBitcoinKey,
c.SecondBitcoinKey,
)
if err != nil {
return err
}
return nil
}
// Command returns the integer uniquely identifying this message type on the
// wire.
//
// This is part of the lnwire.Message interface.
func (c *ChannelAnnouncement) Command() uint32 {
return CmdChannelAnnoucmentMessage
}
// MaxPayloadLength returns the maximum allowed payload size for this message
// observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
func (c *ChannelAnnouncement) MaxPayloadLength(pver uint32) uint32 {
var length uint32
// FirstNodeSig - 64 bytes
length += 64
// SecondNodeSig - 64 bytes
length += 64
// ChannelID - 8 bytes
length += 8
// FirstBitcoinSig - 64 bytes
length += 64
// SecondBitcoinSig - 64 bytes
length += 64
// FirstNodeID - 33 bytes
length += 33
// SecondNodeID - 33 bytes
length += 33
// FirstBitcoinKey - 33 bytes
length += 33
// SecondBitcoinKey - 33 bytes
length += 33
return length
}
// DataToSign is used to retrieve part of the announcement message which
// should be signed.
func (c *ChannelAnnouncement) DataToSign() ([]byte, error) {
// We should not include the signatures itself.
var w bytes.Buffer
err := writeElements(&w,
c.ChannelID,
c.FirstBitcoinSig,
c.SecondBitcoinSig,
c.FirstNodeID,
c.SecondNodeID,
c.FirstBitcoinKey,
c.SecondBitcoinKey,
)
if err != nil {
return nil, err
}
return w.Bytes(), nil
}