lnd.xprv/lnwire/channel_announcement.go

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package lnwire
import (
"bytes"
"io"
"io/ioutil"
"github.com/btcsuite/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.
NodeSig1 Sig
NodeSig2 Sig
// 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.
BitcoinSig1 Sig
BitcoinSig2 Sig
// Features is the feature vector that encodes the features supported
// by the target node. This field can be used to signal the type of the
// channel, or modifications to the fields that would normally follow
// this vector.
Features *RawFeatureVector
// ChainHash denotes the target chain that this channel was opened
// within. This value should be the genesis hash of the target chain.
ChainHash chainhash.Hash
// ShortChannelID is the unique description of the funding transaction,
// or where exactly it's located within the target blockchain.
ShortChannelID ShortChannelID
// The public keys of the two nodes who are operating the channel, such
// that is NodeID1 the numerically-lesser than NodeID2 (ascending
// numerical order).
NodeID1 [33]byte
NodeID2 [33]byte
// Public keys which corresponds to the keys which was declared in
// multisig funding transaction output.
BitcoinKey1 [33]byte
BitcoinKey2 [33]byte
// ExtraOpaqueData is the set of data that was appended to this
// message, some of which we may not actually know how to iterate or
// parse. By holding onto this data, we ensure that we're able to
// properly validate the set of signatures that cover these new fields,
// and ensure we're able to make upgrades to the network in a forwards
// compatible manner.
ExtraOpaqueData []byte
}
// A compile time check to ensure ChannelAnnouncement implements the
// lnwire.Message interface.
var _ Message = (*ChannelAnnouncement)(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.
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func (a *ChannelAnnouncement) Decode(r io.Reader, pver uint32) error {
err := readElements(r,
&a.NodeSig1,
&a.NodeSig2,
&a.BitcoinSig1,
&a.BitcoinSig2,
&a.Features,
a.ChainHash[:],
&a.ShortChannelID,
&a.NodeID1,
&a.NodeID2,
&a.BitcoinKey1,
&a.BitcoinKey2,
)
if err != nil {
return err
}
// Now that we've read out all the fields that we explicitly know of,
// we'll collect the remainder into the ExtraOpaqueData field. If there
// aren't any bytes, then we'll snip off the slice to avoid carrying
// around excess capacity.
a.ExtraOpaqueData, err = ioutil.ReadAll(r)
if err != nil {
return err
}
if len(a.ExtraOpaqueData) == 0 {
a.ExtraOpaqueData = nil
}
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.
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func (a *ChannelAnnouncement) Encode(w io.Writer, pver uint32) error {
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return writeElements(w,
a.NodeSig1,
a.NodeSig2,
a.BitcoinSig1,
a.BitcoinSig2,
a.Features,
a.ChainHash[:],
a.ShortChannelID,
a.NodeID1,
a.NodeID2,
a.BitcoinKey1,
a.BitcoinKey2,
a.ExtraOpaqueData,
)
}
// MsgType returns the integer uniquely identifying this message type on the
// wire.
//
// This is part of the lnwire.Message interface.
func (a *ChannelAnnouncement) MsgType() MessageType {
return MsgChannelAnnouncement
}
// MaxPayloadLength returns the maximum allowed payload size for this message
// observing the specified protocol version.
//
// This is part of the lnwire.Message interface.
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func (a *ChannelAnnouncement) MaxPayloadLength(pver uint32) uint32 {
return 65533
}
// DataToSign is used to retrieve part of the announcement message which should
// be signed.
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func (a *ChannelAnnouncement) DataToSign() ([]byte, error) {
// We should not include the signatures itself.
var w bytes.Buffer
err := writeElements(&w,
a.Features,
a.ChainHash[:],
a.ShortChannelID,
a.NodeID1,
a.NodeID2,
a.BitcoinKey1,
a.BitcoinKey2,
a.ExtraOpaqueData,
)
if err != nil {
return nil, err
}
return w.Bytes(), nil
}