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htlcswitch/link: cleanup spurious fail/settle responses

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This commit is contained in:
Conner Fromknecht 2018-07-27 03:21:12 -07:00
parent 05308ec22c
commit 81b4af2ec8
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GPG Key ID: E7D737B67FA592C7
1 changed files with 111 additions and 11 deletions
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122
htlcswitch/link.go
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@ -1043,6 +1043,7 @@ func (l *channelLink) handleDownStreamPkt(pkt *htlcPacket, isReProcess bool) {
// mailbox, and the HTLC being added to the commitment state.
if l.cfg.DebugHTLC && l.cfg.HodlMask.Active(hodl.AddOutgoing) {
l.warnf(hodl.AddOutgoing.Warning())
l.mailBox.AckPacket(pkt.inKey())
return
}
@ -1097,6 +1098,7 @@ func (l *channelLink) handleDownStreamPkt(pkt *htlcPacket, isReProcess bool) {
err := lnwire.EncodeFailure(&b, failure, 0)
if err != nil {
l.errorf("unable to encode failure: %v", err)
l.mailBox.AckPacket(pkt.inKey())
return
}
reason = lnwire.OpaqueReason(b.Bytes())
@ -1106,6 +1108,7 @@ func (l *channelLink) handleDownStreamPkt(pkt *htlcPacket, isReProcess bool) {
reason, err = pkt.obfuscator.EncryptFirstHop(failure)
if err != nil {
l.errorf("unable to obfuscate error: %v", err)
l.mailBox.AckPacket(pkt.inKey())
return
}
}
@ -1162,22 +1165,38 @@ func (l *channelLink) handleDownStreamPkt(pkt *htlcPacket, isReProcess bool) {
// commitment state.
if l.cfg.DebugHTLC && l.cfg.HodlMask.Active(hodl.SettleOutgoing) {
l.warnf(hodl.SettleOutgoing.Warning())
l.mailBox.AckPacket(pkt.inKey())
return
}
// An HTLC we forward to the switch has just settled somewhere
// upstream. Therefore we settle the HTLC within the our local
// state machine.
closedCircuitRef := pkt.inKey()
if err := l.channel.SettleHTLC(
inKey := pkt.inKey()
err := l.channel.SettleHTLC(
htlc.PaymentPreimage,
pkt.incomingHTLCID,
pkt.sourceRef,
pkt.destRef,
&closedCircuitRef,
); err != nil {
l.fail(LinkFailureError{code: ErrInternalError},
"unable to settle incoming HTLC: %v", err)
&inKey,
)
if err != nil {
l.errorf("unable to settle incoming HTLC for "+
"circuit-key=%v: %v", inKey, err)
// If the HTLC index for Settle response was not known
// to our commitment state, it has already been
// cleaned up by a prior response. We'll thus try to
// clean up any lingering state to ensure we don't
// continue reforwarding.
if _, ok := err.(lnwallet.ErrUnknownHtlcIndex); ok {
l.cleanupSpuriousResponse(pkt)
}
// Remove the packet from the link's mailbox to ensure
// it doesn't get replayed after a reconnection.
l.mailBox.AckPacket(inKey)
return
}
@ -1204,20 +1223,37 @@ func (l *channelLink) handleDownStreamPkt(pkt *htlcPacket, isReProcess bool) {
// state.
if l.cfg.DebugHTLC && l.cfg.HodlMask.Active(hodl.FailOutgoing) {
l.warnf(hodl.FailOutgoing.Warning())
l.mailBox.AckPacket(pkt.inKey())
return
}
// An HTLC cancellation has been triggered somewhere upstream,
// we'll remove then HTLC from our local state machine.
closedCircuitRef := pkt.inKey()
if err := l.channel.FailHTLC(
inKey := pkt.inKey()
err := l.channel.FailHTLC(
pkt.incomingHTLCID,
htlc.Reason,
pkt.sourceRef,
pkt.destRef,
&closedCircuitRef,
); err != nil {
log.Errorf("unable to cancel HTLC: %v", err)
&inKey,
)
if err != nil {
l.errorf("unable to cancel incoming HTLC for "+
"circuit-key=%v: %v", inKey, err)
// If the HTLC index for Fail response was not known to
// our commitment state, it has already been cleaned up
// by a prior response. We'll thus try to clean up any
// lingering state to ensure we don't continue
// reforwarding.
if _, ok := err.(lnwallet.ErrUnknownHtlcIndex); ok {
l.cleanupSpuriousResponse(pkt)
}
// Remove the packet from the link's mailbox to ensure
// it doesn't get replayed after a reconnection.
l.mailBox.AckPacket(inKey)
return
}
@ -1252,6 +1288,70 @@ func (l *channelLink) handleDownStreamPkt(pkt *htlcPacket, isReProcess bool) {
}
}
// cleanupSpuriousResponse attempts to ack any AddRef or SettleFailRef
// associated with this packet. If successful in doing so, it will also purge
// the open circuit from the circuit map and remove the packet from the link's
// mailbox.
func (l *channelLink) cleanupSpuriousResponse(pkt *htlcPacket) {
inKey := pkt.inKey()
l.debugf("Cleaning up spurious response for incoming circuit-key=%v",
inKey)
// If the htlc packet doesn't have a source reference, it is unsafe to
// proceed, as skipping this ack may cause the htlc to be reforwarded.
if pkt.sourceRef == nil {
l.errorf("uanble to cleanup response for incoming "+
"circuit-key=%v, does not contain source reference",
inKey)
return
}
// If the source reference is present, we will try to prevent this link
// from resending the packet to the switch. To do so, we ack the AddRef
// of the incoming HTLC belonging to this link.
err := l.channel.AckAddHtlcs(*pkt.sourceRef)
if err != nil {
l.errorf("unable to ack AddRef for incoming "+
"circuit-key=%v: %v", inKey, err)
// If this operation failed, it is unsafe to attempt removal of
// the destination reference or circuit, so we exit early. The
// cleanup may proceed with a different packet in the future
// that succeeds on this step.
return
}
// Now that we know this link will stop retransmitting Adds to the
// switch, we can begin to teardown the response reference and circuit
// map.
//
// If the packet includes a destination reference, then a response for
// this HTLC was locked into the outgoing channel. Attempt to remove
// this reference, so we stop retransmitting the response internally.
// Even if this fails, we will proceed in trying to delete the circuit.
// When retransmitting responses, the destination references will be
// cleaned up if an open circuit is not found in the circuit map.
if pkt.destRef != nil {
err := l.channel.AckSettleFails(*pkt.destRef)
if err != nil {
l.errorf("unable to ack SettleFailRef "+
"for incoming circuit-key=%v: %v",
inKey, err)
}
}
l.debugf("Deleting circuit for incoming circuit-key=%x", inKey)
// With all known references acked, we can now safely delete the circuit
// from the switch's circuit map, as the state is no longer needed.
err = l.cfg.Circuits.DeleteCircuits(inKey)
if err != nil {
l.errorf("unable to delete circuit for "+
"circuit-key=%v: %v", inKey, err)
}
}
// handleUpstreamMsg processes wire messages related to commitment state
// updates from the upstream peer. The upstream peer is the peer whom we have a
// direct channel with, updating our respective commitment chains.