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htlcswitch: refactor interceptForward

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Preparation for adding on-chain interception.
This commit is contained in:
Joost Jager
2022-03-20 08:19:02 +01:00
parent 4bdc3c9a5b
commit 57e08dfa54
1 changed files with 42 additions and 35 deletions
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77
htlcswitch/interceptable_switch.go
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@ -313,12 +313,6 @@ func (s *InterceptableSwitch) ForwardPackets(linkQuit chan struct{}, isReplay bo
func (s *InterceptableSwitch) interceptForward(packet *htlcPacket, func (s *InterceptableSwitch) interceptForward(packet *htlcPacket,
isReplay bool) bool { isReplay bool) bool {
// Process normally if an interceptor is not required and not
// registered.
if !s.requireInterceptor && s.interceptor == nil {
return false
}
switch htlc := packet.htlc.(type) { switch htlc := packet.htlc.(type) {
case *lnwire.UpdateAddHTLC: case *lnwire.UpdateAddHTLC:
// We are not interested in intercepting initiated payments. // We are not interested in intercepting initiated payments.
@ -326,16 +320,6 @@ func (s *InterceptableSwitch) interceptForward(packet *htlcPacket,
return false return false
} }
inKey := channeldb.CircuitKey{
ChanID: packet.incomingChanID,
HtlcID: packet.incomingHTLCID,
}
// Ignore already held htlcs.
if _, ok := s.holdForwards[inKey]; ok {
return true
}
intercepted := &interceptedForward{ intercepted := &interceptedForward{
htlc: htlc, htlc: htlc,
packet: packet, packet: packet,
@ -363,14 +347,37 @@ func (s *InterceptableSwitch) interceptForward(packet *htlcPacket,
return true return true
} }
if s.interceptor == nil && !isReplay { return s.forward(intercepted, isReplay)
// There is no interceptor registered, we are in
// interceptor-required mode, and this is a new packet default:
// return false
// Because the interceptor has never seen this packet }
// yet, it is still safe to fail back. This limits the }
// backlog of htlcs when the interceptor is down.
err := intercepted.FailWithCode( // forward records the intercepted htlc and forwards it to the interceptor.
func (s *InterceptableSwitch) forward(
fwd InterceptedForward, isReplay bool) bool {
inKey := fwd.Packet().IncomingCircuit
// Ignore already held htlcs.
if _, ok := s.holdForwards[inKey]; ok {
return true
}
// If there is no interceptor currently registered, configuration and packet
// replay status determine how the packet is handled.
if s.interceptor == nil {
// Process normally if an interceptor is not required.
if !s.requireInterceptor {
return false
}
// We are in interceptor-required mode. If this is a new packet, it is
// still safe to fail back. The interceptor has never seen this packet
// yet. This limits the backlog of htlcs when the interceptor is down.
if !isReplay {
err := fwd.FailWithCode(
lnwire.CodeTemporaryChannelFailure, lnwire.CodeTemporaryChannelFailure,
) )
if err != nil { if err != nil {
@ -380,20 +387,20 @@ func (s *InterceptableSwitch) interceptForward(packet *htlcPacket,
return true return true
} }
s.holdForwards[inKey] = intercepted // This packet is a replay. It is not safe to fail back, because the
// interceptor may still signal otherwise upon reconnect. Keep the
// If there is no interceptor registered, we must be in // packet in the queue until then.
// interceptor-required mode. The packet is kept in the queue s.holdForwards[inKey] = fwd
// until the interceptor registers itself.
if s.interceptor != nil {
s.sendForward(intercepted)
}
return true return true
default:
return false
} }
// There is an interceptor registered. We can forward the packet right now.
// Hold it in the queue too to track what is outstanding.
s.holdForwards[inKey] = fwd
s.sendForward(fwd)
return true
} }
// handleExpired checks that the htlc isn't too close to the channel // handleExpired checks that the htlc isn't too close to the channel