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Handle double-HTLC-claims without failing the backwards channel #977

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Merged
merged 4 commits into from
Jul 28, 2021
Merged

Handle double-HTLC-claims without failing the backwards channel #977

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fecac81
Support pending update_fail_htlcs in reconnect_nodes test util
TheBlueMatt Jul 14, 2021
7e78fa6
Handle double-HTLC-claims without failing the backwards channel
TheBlueMatt Jun 29, 2021
c09104f
Simplify call graph of get_update_fulfill_htlc since it can't Err.
TheBlueMatt Jul 15, 2021
f06f9d1
Fail channel if we can't sign a new commitment tx during HTLC claim
TheBlueMatt Jul 15, 2021
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2 changes: 1 addition & 1 deletion lightning/src/chain/channelmonitor.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -114,7 +114,7 @@ impl Readable for ChannelMonitorUpdate {
}

/// An error enum representing a failure to persist a channel monitor update.
#[derive(Clone, Debug)]
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum ChannelMonitorUpdateErr {
/// Used to indicate a temporary failure (eg connection to a watchtower or remote backup of
/// our state failed, but is expected to succeed at some point in the future).
Expand Down
122 changes: 119 additions & 3 deletions lightning/src/ln/chanmon_update_fail_tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -197,7 +197,7 @@ fn do_test_simple_monitor_temporary_update_fail(disconnect: bool, persister_fail
if disconnect {
nodes[0].node.peer_disconnected(&nodes[1].node.get_our_node_id(), false);
nodes[1].node.peer_disconnected(&nodes[0].node.get_our_node_id(), false);
reconnect_nodes(&nodes[0], &nodes[1], (true, true), (0, 0), (0, 0), (0, 0), (0, 0), (false, false));
reconnect_nodes(&nodes[0], &nodes[1], (true, true), (0, 0), (0, 0), (0, 0), (0, 0), (0, 0), (false, false));
}

match persister_fail {
Expand Down Expand Up @@ -251,7 +251,7 @@ fn do_test_simple_monitor_temporary_update_fail(disconnect: bool, persister_fail
if disconnect {
nodes[0].node.peer_disconnected(&nodes[1].node.get_our_node_id(), false);
nodes[1].node.peer_disconnected(&nodes[0].node.get_our_node_id(), false);
reconnect_nodes(&nodes[0], &nodes[1], (false, false), (0, 0), (0, 0), (0, 0), (0, 0), (false, false));
reconnect_nodes(&nodes[0], &nodes[1], (false, false), (0, 0), (0, 0), (0, 0), (0, 0), (0, 0), (false, false));
}

// ...and make sure we can force-close a frozen channel
Expand Down Expand Up @@ -1912,7 +1912,7 @@ fn do_during_funding_monitor_fail(confirm_a_first: bool, restore_b_before_conf:
// Make sure nodes[1] isn't stupid enough to re-send the FundingLocked on reconnect
nodes[0].node.peer_disconnected(&nodes[1].node.get_our_node_id(), false);
nodes[1].node.peer_disconnected(&nodes[0].node.get_our_node_id(), false);
reconnect_nodes(&nodes[0], &nodes[1], (false, confirm_a_first), (0, 0), (0, 0), (0, 0), (0, 0), (false, false));
reconnect_nodes(&nodes[0], &nodes[1], (false, confirm_a_first), (0, 0), (0, 0), (0, 0), (0, 0), (0, 0), (false, false));
assert!(nodes[0].node.get_and_clear_pending_msg_events().is_empty());
assert!(nodes[1].node.get_and_clear_pending_msg_events().is_empty());

Expand Down Expand Up @@ -2215,3 +2215,119 @@ fn channel_holding_cell_serialize() {
do_channel_holding_cell_serialize(true, false);
do_channel_holding_cell_serialize(false, true); // last arg doesn't matter
}

#[derive(PartialEq)]
enum HTLCStatusAtDupClaim {
Received,
HoldingCell,
Cleared,
}
fn do_test_reconnect_dup_htlc_claims(htlc_status: HTLCStatusAtDupClaim, second_fails: bool) {
// When receiving an update_fulfill_htlc message, we immediately forward the claim backwards
// along the payment path before waiting for a full commitment_signed dance. This is great, but
// can cause duplicative claims if a node sends an update_fulfill_htlc message, disconnects,
// reconnects, and then has to re-send its update_fulfill_htlc message again.
// In previous code, we didn't handle the double-claim correctly, spuriously closing the
// channel on which the inbound HTLC was received.
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Are you saying that previous to this PR, if we did receive a duplicate update_fulfiil_htlc on the forward channel, we would have close the backward one ? You're referring to current get_update_fulfill_htlc or another behavior? Don't get it here...

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Are you saying that previous to this PR, if we did receive a duplicate update_fulfiil_htlc on the forward channel, we would have close the backward one

Yes, that's correct. We'd debug_assert!(false, ... then close the channel when debug assertions were off.

let chanmon_cfgs = create_chanmon_cfgs(3);
let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
let mut nodes = create_network(3, &node_cfgs, &node_chanmgrs);

create_announced_chan_between_nodes(&nodes, 0, 1, InitFeatures::known(), InitFeatures::known());
let chan_2 = create_announced_chan_between_nodes(&nodes, 1, 2, InitFeatures::known(), InitFeatures::known()).2;

let (payment_preimage, payment_hash, _) = route_payment(&nodes[0], &[&nodes[1], &nodes[2]], 100_000);

let mut as_raa = None;
if htlc_status == HTLCStatusAtDupClaim::HoldingCell {
// In order to get the HTLC claim into the holding cell at nodes[1], we need nodes[1] to be
// awaiting a remote revoke_and_ack from nodes[0].
let (_, second_payment_hash, second_payment_secret) = get_payment_preimage_hash!(nodes[1]);
let route = get_route(&nodes[0].node.get_our_node_id(), &nodes[0].net_graph_msg_handler.network_graph.read().unwrap(),
&nodes[1].node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), 100_000, TEST_FINAL_CLTV, nodes[1].logger).unwrap();
nodes[0].node.send_payment(&route, second_payment_hash, &Some(second_payment_secret)).unwrap();
check_added_monitors!(nodes[0], 1);

let send_event = SendEvent::from_event(nodes[0].node.get_and_clear_pending_msg_events().remove(0));
nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &send_event.msgs[0]);
nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &send_event.commitment_msg);
check_added_monitors!(nodes[1], 1);

let (bs_raa, bs_cs) = get_revoke_commit_msgs!(nodes[1], nodes[0].node.get_our_node_id());
nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_raa);
check_added_monitors!(nodes[0], 1);
nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &bs_cs);
check_added_monitors!(nodes[0], 1);

as_raa = Some(get_event_msg!(nodes[0], MessageSendEvent::SendRevokeAndACK, nodes[1].node.get_our_node_id()));
}

let fulfill_msg = msgs::UpdateFulfillHTLC {
channel_id: chan_2,
htlc_id: 0,
payment_preimage,
};
if second_fails {
assert!(nodes[2].node.fail_htlc_backwards(&payment_hash));
expect_pending_htlcs_forwardable!(nodes[2]);
check_added_monitors!(nodes[2], 1);
get_htlc_update_msgs!(nodes[2], nodes[1].node.get_our_node_id());
} else {
assert!(nodes[2].node.claim_funds(payment_preimage));
check_added_monitors!(nodes[2], 1);
let cs_updates = get_htlc_update_msgs!(nodes[2], nodes[1].node.get_our_node_id());
assert_eq!(cs_updates.update_fulfill_htlcs.len(), 1);
// Check that the message we're about to deliver matches the one generated:
assert_eq!(fulfill_msg, cs_updates.update_fulfill_htlcs[0]);
}
nodes[1].node.handle_update_fulfill_htlc(&nodes[2].node.get_our_node_id(), &fulfill_msg);
check_added_monitors!(nodes[1], 1);

let mut bs_updates = None;
if htlc_status != HTLCStatusAtDupClaim::HoldingCell {
bs_updates = Some(get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id()));
assert_eq!(bs_updates.as_ref().unwrap().update_fulfill_htlcs.len(), 1);
nodes[0].node.handle_update_fulfill_htlc(&nodes[1].node.get_our_node_id(), &bs_updates.as_ref().unwrap().update_fulfill_htlcs[0]);
expect_payment_sent!(nodes[0], payment_preimage);
if htlc_status == HTLCStatusAtDupClaim::Cleared {
commitment_signed_dance!(nodes[0], nodes[1], &bs_updates.as_ref().unwrap().commitment_signed, false);
}
} else {
assert!(nodes[1].node.get_and_clear_pending_msg_events().is_empty());
}

nodes[1].node.peer_disconnected(&nodes[2].node.get_our_node_id(), false);
nodes[2].node.peer_disconnected(&nodes[1].node.get_our_node_id(), false);

if second_fails {
reconnect_nodes(&nodes[1], &nodes[2], (false, false), (0, 0), (0, 0), (1, 0), (0, 0), (0, 0), (false, false));
expect_pending_htlcs_forwardable!(nodes[1]);
} else {
reconnect_nodes(&nodes[1], &nodes[2], (false, false), (0, 0), (1, 0), (0, 0), (0, 0), (0, 0), (false, false));
}

if htlc_status == HTLCStatusAtDupClaim::HoldingCell {
nodes[1].node.handle_revoke_and_ack(&nodes[0].node.get_our_node_id(), &as_raa.unwrap());
check_added_monitors!(nodes[1], 1);
expect_pending_htlcs_forwardable_ignore!(nodes[1]); // We finally receive the second payment, but don't claim it

bs_updates = Some(get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id()));
assert_eq!(bs_updates.as_ref().unwrap().update_fulfill_htlcs.len(), 1);
nodes[0].node.handle_update_fulfill_htlc(&nodes[1].node.get_our_node_id(), &bs_updates.as_ref().unwrap().update_fulfill_htlcs[0]);
expect_payment_sent!(nodes[0], payment_preimage);
}
if htlc_status != HTLCStatusAtDupClaim::Cleared {
commitment_signed_dance!(nodes[0], nodes[1], &bs_updates.as_ref().unwrap().commitment_signed, false);
}
}

#[test]
fn test_reconnect_dup_htlc_claims() {
do_test_reconnect_dup_htlc_claims(HTLCStatusAtDupClaim::Received, false);
do_test_reconnect_dup_htlc_claims(HTLCStatusAtDupClaim::HoldingCell, false);
do_test_reconnect_dup_htlc_claims(HTLCStatusAtDupClaim::Cleared, false);
do_test_reconnect_dup_htlc_claims(HTLCStatusAtDupClaim::Received, true);
do_test_reconnect_dup_htlc_claims(HTLCStatusAtDupClaim::HoldingCell, true);
do_test_reconnect_dup_htlc_claims(HTLCStatusAtDupClaim::Cleared, true);
}
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