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link: increase expiry grace delta

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This commit increase the expiry grace delta to a value above the
broadcast delta. This prevents htlcs from being accepted that would
immediately trigger a channel force close.

A correct delta is generated in server.go where there is access to
the broadcast delta and passed via the peer to the links.

Co-authored-by: Jim Posen <jim.posen@gmail.com>
This commit is contained in:
Joost JagerandJim Posen committed 2019-03-26 18:42:00 +01:00
1 parent e6fbbaa1dc
commit cd535b9401
6 files changed
+77 -37
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htlcswitch/link.go
+16 -16
View File
@@ -30,18 +30,6 @@ func init() {
}
const (
// expiryGraceDelta is the minimum difference between the current block
// height and the CLTV we require on 1) an outgoing HTLC in order to
// forward as an intermediary hop, or 2) an incoming HTLC to reveal the
// preimage as the final hop. We'll reject any HTLC's who's timeout minus
// this value is less than or equal to the current block height. We require
// this in order to ensure that we have sufficient time to claim or
// timeout an HTLC on chain.
//
// This MUST be greater than the maximum BroadcastDelta of the
// ChannelArbitrator for the outbound channel.
expiryGraceDelta = 2
// maxCltvExpiry is the maximum outgoing time lock that the node accepts
// for forwarded payments. The value is relative to the current block
// height. The reason to have a maximum is to prevent funds getting
@@ -246,6 +234,18 @@ type ChannelLinkConfig struct {
// fee rate. A random timeout will be selected between these values.
MinFeeUpdateTimeout time.Duration
MaxFeeUpdateTimeout time.Duration
// ExpiryGraceDelta is the minimum difference between the current block
// height and the CLTV we require on 1) an outgoing HTLC in order to
// forward as an intermediary hop, or 2) an incoming HTLC to reveal the
// preimage as the final hop. We'll reject any HTLC's who's timeout minus
// this value is less than or equal to the current block height. We require
// this in order to ensure that we have sufficient time to claim or
// timeout an HTLC on chain.
//
// This MUST be greater than the maximum BroadcastDelta of the
// ChannelArbitrator for the outbound channel.
ExpiryGraceDelta uint32
}
// channelLink is the service which drives a channel's commitment update
@@ -2150,9 +2150,9 @@ func (l *channelLink) HtlcSatifiesPolicy(payHash [32]byte,
}
// We want to avoid offering an HTLC which will expire in the near
// future, so we'll reject an HTLC if the outgoing expiration time is
// too close to the current height.
if outgoingTimeout-expiryGraceDelta <= heightNow {
// future, so we'll reject an HTLC if the outgoing expiration time is too
// close to the current height.
if outgoingTimeout-l.cfg.ExpiryGraceDelta <= heightNow {
l.errorf("htlc(%x) has an expiry that's too soon: "+
"outgoing_expiry=%v, best_height=%v", payHash[:],
outgoingTimeout, heightNow)
@@ -2675,7 +2675,7 @@ func (l *channelLink) processExitHop(pd *lnwallet.PaymentDescriptor,
// First, we'll check the expiry of the HTLC itself against, the current
// block height. If the timeout is too soon, then we'll reject the HTLC.
if pd.Timeout-expiryGraceDelta <= heightNow {
if pd.Timeout-l.cfg.ExpiryGraceDelta <= heightNow {
log.Errorf("htlc(%x) has an expiry that's too soon: expiry=%v"+
", best_height=%v", pd.RHash[:], pd.Timeout, heightNow)