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htlcswitch: properly verify OutgoingCTLV+Timeout when final hop in link

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This commit fixes an existing bug in the way we perform validation of
the timelock information as the final hop in the route. Previously, we
would assert that the outgoing time lock in the per-hop payload would
exactly match our time lock delta.

Instead, we should be asserting two things:
   1. That the time lock in the payload is >= the expected time lock
   2. That timeout on the HTLC is exactly equal to the payload
This commit is contained in:
Olaoluwa Osuntokun 2017-09-12 22:04:52 +02:00
parent 246164e290
commit bf071c1985
No known key found for this signature in database
GPG Key ID: 964EA263DD637C21
1 changed files with 47 additions and 22 deletions
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69
htlcswitch/link.go
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@ -865,6 +865,7 @@ func (l *channelLink) Bandwidth() lnwire.MilliSatoshi {
// NOTE: Should be used inside main goroutine only, otherwise the result might
// not be accurate.
func (l *channelLink) getBandwidth() lnwire.MilliSatoshi {
// TODO(roasbeef): factor in reserve, just grab mutex
return l.channel.LocalAvailableBalance() - l.overflowQueue.pendingAmount()
}
@ -1026,15 +1027,19 @@ func (l *channelLink) processLockedInHtlcs(
// to produce initial obfuscation of the onion
// failureCode.
onionReader := bytes.NewReader(onionBlob[:])
obfuscator, failureCode := l.cfg.DecodeOnionObfuscator(onionReader)
obfuscator, failureCode := l.cfg.DecodeOnionObfuscator(
onionReader,
)
if failureCode != lnwire.CodeNone {
// If we unable to process the onion blob than
// we should send the malformed htlc error to
// payment sender.
l.sendMalformedHTLCError(pd.RHash, failureCode, onionBlob[:])
// If we're unable to process the onion blob
// than we should send the malformed htlc error
// to payment sender.
l.sendMalformedHTLCError(pd.RHash, failureCode,
onionBlob[:])
needUpdate = true
log.Error("unable to decode onion obfuscator")
log.Errorf("unable to decode onion "+
"obfuscator: %v", failureCode)
continue
}
@ -1054,13 +1059,15 @@ func (l *channelLink) processLockedInHtlcs(
onionReader, pd.RHash[:],
)
if failureCode != lnwire.CodeNone {
// If we unable to process the onion blob than
// we should send the malformed htlc error to
// payment sender.
l.sendMalformedHTLCError(pd.RHash, failureCode, onionBlob[:])
// If we're unable to process the onion blob
// than we should send the malformed htlc error
// to payment sender.
l.sendMalformedHTLCError(pd.RHash, failureCode,
onionBlob[:])
needUpdate = true
log.Error("unable to decode onion hop iterator")
log.Errorf("unable to decode onion hop "+
"iterator: %v", failureCode)
continue
}
@ -1122,19 +1129,35 @@ func (l *channelLink) processLockedInHtlcs(
// We'll also ensure that our time-lock value
// has been computed correctly.
if !l.cfg.DebugHTLC &&
fwdInfo.OutgoingCTLV != l.cfg.FwrdingPolicy.TimeLockDelta {
expectedHeight := heightNow + l.cfg.FwrdingPolicy.TimeLockDelta
if !l.cfg.DebugHTLC {
switch {
case fwdInfo.OutgoingCTLV < expectedHeight:
log.Errorf("Onion payload of incoming "+
"htlc(%x) has incorrect time-lock: "+
"expected %v, got %v",
pd.RHash[:], expectedHeight,
fwdInfo.OutgoingCTLV)
log.Errorf("Onion payload of incoming "+
"htlc(%x) has incorrect time-lock: "+
"expected %v, got %v",
pd.RHash[:], l.cfg.FwrdingPolicy.TimeLockDelta,
fwdInfo.OutgoingCTLV)
failure := lnwire.NewFinalIncorrectCltvExpiry(
fwdInfo.OutgoingCTLV,
)
l.sendHTLCError(pd.RHash, failure, obfuscator)
needUpdate = true
continue
case pd.Timeout != fwdInfo.OutgoingCTLV:
log.Errorf("HTLC(%x) has incorrect "+
"time-lock: expected %v, got %v",
pd.RHash[:], pd.Timeout,
fwdInfo.OutgoingCTLV)
failure := lnwire.NewFinalIncorrectCltvExpiry(fwdInfo.OutgoingCTLV)
l.sendHTLCError(pd.RHash, failure, obfuscator)
needUpdate = true
continue
failure := lnwire.NewFinalIncorrectCltvExpiry(
fwdInfo.OutgoingCTLV,
)
l.sendHTLCError(pd.RHash, failure, obfuscator)
needUpdate = true
continue
}
}
// If we're not currently in debug mode, and
@ -1307,6 +1330,8 @@ func (l *channelLink) processLockedInHtlcs(
continue
}
// TODO(roasbeef): also add max timeout value
// With all our forwarding constraints met,
// we'll create the outgoing HTLC using the
// parameters as specified in the forwarding