htlcswitch+channel: add channel states synchronization
In this commit BOLT№2 retranmission logic for the channel link have been added. Now if channel link have been initialised with the 'SyncState' field than it will send the lnwire.ChannelReestablish message and will be waiting for receiving the same message from remote side. Exchange of this message allow both sides understand which updates they should exchange with each other in order sync their states.
This commit is contained in:
Andrey Samokhvalov authored and Olaoluwa Osuntokun committed
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@@ -4,6 +4,7 @@ import (
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"bytes"
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"container/list"
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"crypto/sha256"
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"errors"
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"fmt"
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"runtime"
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"sort"
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@@ -2428,6 +2429,132 @@ func (lc *LightningChannel) SignNextCommitment() (*btcec.Signature, []*btcec.Sig
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return sig, htlcSigs, nil
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}
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// ReceiveReestablish is used to handle the remote channel reestablish message
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// and generate the set of updates which are have to be sent to remote side
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// to synchronize the states of the channels.
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func (lc *LightningChannel) ReceiveReestablish(msg *lnwire.ChannelReestablish) (
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[]lnwire.Message, error) {
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lc.Lock()
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defer lc.Unlock()
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var updates []lnwire.Message
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// As far we store on last commitment transaction we should rely on the
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// height of the commitment transaction in order to calculate the length.
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numberRemoteCommitments := lc.remoteCommitChain.tip().height + 1
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// Number of the revocations might be calculated as the height of the
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// commitment transactions which will be revoked next minus one. And plus
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// one because height starts from zero.
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numberRemoteRevocations := lc.localCommitChain.tail().height - 1 + 1
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revocationsnumberDiff := msg.NextRemoteRevocationNumber - numberRemoteRevocations
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if revocationsnumberDiff == 0 {
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// If remote side expects as receive revocation which we already
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// consider as last, than it means that they aren't received our
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// last revocation message.
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revocationMsg, err := lc.generateRevocation(lc.currentHeight - 1)
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if err != nil {
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return nil, err
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}
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updates = append(updates, revocationMsg)
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} else if revocationsnumberDiff < 0 {
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// Remote node claims that it received the revoke_and_ack message
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// which we did not send.
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return nil, errors.New("remote side claims that it haven't received " +
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"acked revoke and ack message")
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}
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commitmentChainDiff := msg.NextLocalCommitmentNumber - numberRemoteCommitments
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if commitmentChainDiff == 0 {
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// If remote side expects as receive commitment which we already
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// consider as last, than it means that they aren't received our
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// last commit sig message.
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commitment := lc.remoteCommitChain.tip()
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chanID := lnwire.NewChanIDFromOutPoint(&lc.channelState.FundingOutpoint)
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for _, htlc := range commitment.outgoingHTLCs {
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// If htlc is included in the local commitment chain (have been
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// included by remote side) or htlc is included in remote chain, but
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// not in the last commimemnt transaction than we should skip it,
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// because we need resend only updates which haven't been received
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// by remotes side.
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if htlc.addCommitHeightLocal != 0 ||
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(htlc.addCommitHeightLocal != 0 &&
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htlc.addCommitHeightLocal <= commitment.height) {
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continue
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}
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switch htlc.EntryType {
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case Add:
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var onionBlob [lnwire.OnionPacketSize]byte
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copy(onionBlob[:], htlc.Payload)
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updates = append(updates, &lnwire.UpdateAddHTLC{
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ChanID: chanID,
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ID: htlc.Index,
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Expiry: htlc.Timeout,
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Amount: htlc.Amount,
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PaymentHash: htlc.RHash,
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OnionBlob: onionBlob,
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})
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case Fail:
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updates = append(updates, &lnwire.UpdateFailHTLC{
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ChanID: chanID,
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ID: htlc.Index,
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Reason: lnwire.OpaqueReason([]byte{}),
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})
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case Settle:
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updates = append(updates, &lnwire.UpdateFufillHTLC{
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ChanID: chanID,
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ID: htlc.Index,
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PaymentPreimage: htlc.RPreimage,
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})
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}
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}
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// Generate last sent commit sig message by signing the transaction and
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// creating the signature.
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lc.signDesc.SigHashes = txscript.NewTxSigHashes(commitment.txn)
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sig, err := lc.signer.SignOutputRaw(commitment.txn, lc.signDesc)
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if err != nil {
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return nil, err
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}
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commitSig, err := btcec.ParseSignature(sig, btcec.S256())
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if err != nil {
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return nil, err
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}
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updates = append(updates, &lnwire.CommitSig{
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ChanID: chanID,
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CommitSig: commitSig,
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})
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} else if commitmentChainDiff < 0 {
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// Remote node claims that it received the commit sig message which we
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// did not send.
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return nil, errors.New("remote side claims that it haven't received " +
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"acked commit sig message")
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}
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return updates, nil
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}
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// LastCounters returns the historical length of the local commimemnt
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// transaction chain and the historical number of the the revocked commiment
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// transactions, whicha are needed in order to generate the channel
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// reestablish message.
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func (lc *LightningChannel) LastCounters() (uint64, uint64) {
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// As far we store on last commitment transaction we should rely on the
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// height of the commitment transaction in order to calculate the length.
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numberLocalCommitments := lc.localCommitChain.tip().height + 1
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// Number of the revocations might be calculated as the height of the
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// commitment transactions which will be revoked next minus one. And plus
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// one because height starts from zero.
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numberRemoteRevocations := lc.remoteCommitChain.tail().height - 1 + 1
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return numberLocalCommitments, numberRemoteRevocations
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}
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// validateCommitmentSanity is used to validate that on current state the commitment
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// transaction is valid in terms of propagating it over Bitcoin network, and
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// also that all outputs are meet Bitcoin spec requirements and they are
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@@ -2782,43 +2909,13 @@ func (lc *LightningChannel) RevokeCurrentCommitment() (*lnwire.RevokeAndAck, err
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lc.Lock()
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defer lc.Unlock()
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// Now that we've accept a new state transition, we send the remote
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// party the revocation for our current commitment state.
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revocationMsg := &lnwire.RevokeAndAck{}
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commitSecret, err := lc.channelState.RevocationProducer.AtIndex(
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lc.currentHeight,
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)
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revocationMsg, err := lc.generateRevocation(lc.currentHeight)
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if err != nil {
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return nil, err
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}
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copy(revocationMsg.Revocation[:], commitSecret[:])
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// Along with this revocation, we'll also send the _next_ commitment
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// point that the remote party should use to create our next commitment
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// transaction. We use a +2 here as we already gave them a look ahead
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// of size one after the FundingLocked message was sent:
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//
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// 0: current revocation, 1: their "next" revocation, 2: this revocation
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//
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// We're revoking the current revocation. Once they receive this
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// message they'll set the "current" revocation for us to their stored
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// "next" revocation, and this revocation will become their new "next"
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// revocation.
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//
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// Put simply in the window slides to the left by one.
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nextCommitSecret, err := lc.channelState.RevocationProducer.AtIndex(
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lc.currentHeight + 2,
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)
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if err != nil {
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return nil, err
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}
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revocationMsg.NextRevocationKey = ComputeCommitmentPoint(
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nextCommitSecret[:],
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)
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walletLog.Tracef("ChannelPoint(%v): revoking height=%v, now at height=%v",
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lc.channelState.FundingOutpoint, lc.localCommitChain.tail().height,
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lc.currentHeight+1)
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walletLog.Tracef("ChannelPoint(%v): revoking height=%v, now at height=%v", lc.channelState.FundingOutpoint,
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lc.localCommitChain.tail().height, lc.currentHeight+1)
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// Advance our tail, as we've revoked our previous state.
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lc.localCommitChain.advanceTail()
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@@ -3860,6 +3957,47 @@ func (lc *LightningChannel) ReceiveUpdateFee(feePerKw btcutil.Amount) error {
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return nil
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}
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// generateRevocation generate lnwire revocation message by the given height
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// and revocation edge.
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func (lc *LightningChannel) generateRevocation(height uint64) (*lnwire.RevokeAndAck,
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error) {
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// Now that we've accept a new state transition, we send the remote
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// party the revocation for our current commitment state.
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revocationMsg := &lnwire.RevokeAndAck{}
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commitSecret, err := lc.channelState.RevocationProducer.AtIndex(height)
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if err != nil {
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return nil, err
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}
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copy(revocationMsg.Revocation[:], commitSecret[:])
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// Along with this revocation, we'll also send the _next_ commitment
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// point that the remote party should use to create our next commitment
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// transaction. We use a +2 here as we already gave them a look ahead
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// of size one after the FundingLocked message was sent:
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//
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// 0: current revocation, 1: their "next" revocation, 2: this revocation
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//
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// We're revoking the current revocation. Once they receive this
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// message they'll set the "current" revocation for us to their stored
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// "next" revocation, and this revocation will become their new "next"
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// revocation.
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//
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// Put simply in the window slides to the left by one.
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nextCommitSecret, err := lc.channelState.RevocationProducer.AtIndex(
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height + 2,
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)
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if err != nil {
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return nil, err
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}
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revocationMsg.NextRevocationKey = ComputeCommitmentPoint(nextCommitSecret[:])
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revocationMsg.ChanID = lnwire.NewChanIDFromOutPoint(
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&lc.channelState.FundingOutpoint)
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return revocationMsg, nil
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}
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// CreateCommitTx creates a commitment transaction, spending from specified
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// funding output. The commitment transaction contains two outputs: one paying
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// to the "owner" of the commitment transaction which can be spent after a
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