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htlcswitch/link: remove deadlock in htlc validation

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This commit removes a possible deadlock in the switch,
which can be triggered under certain failure conditions.
Previously, we would acquire the link's read lock for
the duration of HtlcSatisfiesPolicy, though we only
need to use it grab the current policy. The deadlock could
be caused in the cases where we attempt to log the failure,
which access the read-protected ShortChanID method.
This commit is contained in:
Conner Fromknecht 2018-06-06 18:07:20 -07:00
parent 849ee5e0dc
commit c180065a84
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GPG Key ID: 39DE78FBE6ACB0EF
1 changed files with 5 additions and 4 deletions
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9
htlcswitch/link.go
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@ -1714,14 +1714,15 @@ func (l *channelLink) HtlcSatifiesPolicy(payHash [32]byte,
incomingHtlcAmt, amtToForward lnwire.MilliSatoshi) lnwire.FailureMessage {
l.RLock()
defer l.RUnlock()
policy := l.cfg.FwrdingPolicy
l.RUnlock()
// As our first sanity check, we'll ensure that the passed HTLC isn't
// too small for the next hop. If so, then we'll cancel the HTLC
// directly.
if amtToForward < l.cfg.FwrdingPolicy.MinHTLC {
if amtToForward < policy.MinHTLC {
l.errorf("outgoing htlc(%x) is too small: min_htlc=%v, "+
"htlc_value=%v", payHash[:], l.cfg.FwrdingPolicy.MinHTLC,
"htlc_value=%v", payHash[:], policy.MinHTLC,
amtToForward)
// As part of the returned error, we'll send our latest routing
@ -1742,7 +1743,7 @@ func (l *channelLink) HtlcSatifiesPolicy(payHash [32]byte,
// Next, using the amount of the incoming HTLC, we'll calculate the
// expected fee this incoming HTLC must carry in order to satisfy the
// constraints of the outgoing link.
expectedFee := ExpectedFee(l.cfg.FwrdingPolicy, amtToForward)
expectedFee := ExpectedFee(policy, amtToForward)
// If the actual fee is less than our expected fee, then we'll reject
// this HTLC as it didn't provide a sufficient amount of fees, or the