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Ignore channel updates in onion errors.
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Per <lightning/bolts#1163>.
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@valentinewallace
valentinewallace committed May 24, 2024
1 parent 1d421d3 commit 24c2468
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Showing 3 changed files with 46 additions and 122 deletions.
4 changes: 2 additions & 2 deletions lightning/src/ln/functional_test_utils.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2460,11 +2460,11 @@ pub fn expect_payment_failed_conditions_event<'a, 'b, 'c, 'd, 'e>(
const CHAN_DISABLED_FLAG: u8 = 2;
assert_eq!(msg.contents.flags & CHAN_DISABLED_FLAG, 0);
},
NetworkUpdate::ChannelFailure { short_channel_id, is_permanent } if chan_closed => {
NetworkUpdate::ChannelFailure { short_channel_id, is_permanent } => {
if let Some(scid) = conditions.expected_blamed_scid {
assert_eq!(*short_channel_id, scid);
}
assert!(is_permanent);
assert_eq!(*is_permanent, chan_closed);
},
_ => panic!("Unexpected update type"),
}
Expand Down
59 changes: 37 additions & 22 deletions lightning/src/ln/onion_route_tests.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -300,12 +300,13 @@ fn test_fee_failures() {
claim_payment(&nodes[0], &[&nodes[1], &nodes[2]], payment_preimage_success);

// If the hop gives fee_insufficient but enough fees were provided, then the previous hop
// malleated the payment before forwarding, taking funds when they shouldn't have.
// malleated the payment before forwarding, taking funds when they shouldn't have. However,
// because we ignore channel update contents, we will still blame the 2nd channel.
let (_, payment_hash, payment_secret) = get_payment_preimage_hash!(nodes[2]);
let short_channel_id = channels[0].0.contents.short_channel_id;
let short_channel_id = channels[1].0.contents.short_channel_id;
run_onion_failure_test("fee_insufficient", 0, &nodes, &route, &payment_hash, &payment_secret, |msg| {
msg.amount_msat -= 1;
}, || {}, true, Some(UPDATE|12), Some(NetworkUpdate::ChannelFailure { short_channel_id, is_permanent: true}), Some(short_channel_id));
}, || {}, true, Some(UPDATE|12), Some(NetworkUpdate::ChannelFailure { short_channel_id, is_permanent: false}), Some(short_channel_id));

// In an earlier version, we spuriously failed to forward payments if the expected feerate
// changed between the channel open and the payment.
Expand Down Expand Up @@ -478,7 +479,9 @@ fn test_onion_failure() {
let session_priv = SecretKey::from_slice(&[3; 32]).unwrap();
let onion_keys = onion_utils::construct_onion_keys(&Secp256k1::new(), &route.paths[0], &session_priv).unwrap();
msg.reason = onion_utils::build_first_hop_failure_packet(onion_keys[0].shared_secret.as_ref(), UPDATE|7, &err_data);
}, ||{}, true, Some(UPDATE|7), Some(NetworkUpdate::ChannelUpdateMessage{msg: chan_update.clone()}), Some(short_channel_id));
}, ||{}, true, Some(UPDATE|7),
Some(NetworkUpdate::ChannelFailure { short_channel_id, is_permanent: false }),
Some(short_channel_id));

// Check we can still handle onion failures that include channel updates without a type prefix
let err_data_without_type = chan_update.encode_with_len();
Expand All @@ -488,7 +491,9 @@ fn test_onion_failure() {
let session_priv = SecretKey::from_slice(&[3; 32]).unwrap();
let onion_keys = onion_utils::construct_onion_keys(&Secp256k1::new(), &route.paths[0], &session_priv).unwrap();
msg.reason = onion_utils::build_first_hop_failure_packet(onion_keys[0].shared_secret.as_ref(), UPDATE|7, &err_data_without_type);
}, ||{}, true, Some(UPDATE|7), Some(NetworkUpdate::ChannelUpdateMessage{msg: chan_update}), Some(short_channel_id));
}, ||{}, true, Some(UPDATE|7),
Some(NetworkUpdate::ChannelFailure { short_channel_id, is_permanent: false }),
Some(short_channel_id));

let short_channel_id = channels[1].0.contents.short_channel_id;
run_onion_failure_test_with_fail_intercept("permanent_channel_failure", 100, &nodes, &route, &payment_hash, &payment_secret, |msg| {
Expand Down Expand Up @@ -523,7 +528,9 @@ fn test_onion_failure() {
let mut bogus_route = route.clone();
let route_len = bogus_route.paths[0].hops.len();
bogus_route.paths[0].hops[route_len-1].fee_msat = amt_to_forward;
run_onion_failure_test("amount_below_minimum", 0, &nodes, &bogus_route, &payment_hash, &payment_secret, |_| {}, ||{}, true, Some(UPDATE|11), Some(NetworkUpdate::ChannelUpdateMessage{msg: ChannelUpdate::dummy(short_channel_id)}), Some(short_channel_id));
run_onion_failure_test("amount_below_minimum", 0, &nodes, &bogus_route, &payment_hash, &payment_secret, |_| {}, ||{}, true, Some(UPDATE|11),
Some(NetworkUpdate::ChannelFailure { short_channel_id, is_permanent: false }),
Some(short_channel_id));

// Clear pending payments so that the following positive test has the correct payment hash.
for node in nodes.iter() {
Expand All @@ -535,24 +542,28 @@ fn test_onion_failure() {
let preimage = send_along_route(&nodes[0], bogus_route, &[&nodes[1], &nodes[2]], amt_to_forward+1).0;
claim_payment(&nodes[0], &[&nodes[1], &nodes[2]], preimage);

let short_channel_id = channels[0].0.contents.short_channel_id;
// We ignore channel update contents in onion errors, so will blame the 2nd channel even though
// the first node is the one that messed up.
let short_channel_id = channels[1].0.contents.short_channel_id;
run_onion_failure_test("fee_insufficient", 0, &nodes, &route, &payment_hash, &payment_secret, |msg| {
msg.amount_msat -= 1;
}, || {}, true, Some(UPDATE|12), Some(NetworkUpdate::ChannelFailure { short_channel_id, is_permanent: true}), Some(short_channel_id));
}, || {}, true, Some(UPDATE|12), Some(NetworkUpdate::ChannelFailure { short_channel_id, is_permanent: false}), Some(short_channel_id));

let short_channel_id = channels[0].0.contents.short_channel_id;
let short_channel_id = channels[1].0.contents.short_channel_id;
run_onion_failure_test("incorrect_cltv_expiry", 0, &nodes, &route, &payment_hash, &payment_secret, |msg| {
// need to violate: cltv_expiry - cltv_expiry_delta >= outgoing_cltv_value
msg.cltv_expiry -= 1;
}, || {}, true, Some(UPDATE|13), Some(NetworkUpdate::ChannelFailure { short_channel_id, is_permanent: true}), Some(short_channel_id));
}, || {}, true, Some(UPDATE|13), Some(NetworkUpdate::ChannelFailure { short_channel_id, is_permanent: false}), Some(short_channel_id));

let short_channel_id = channels[1].0.contents.short_channel_id;
run_onion_failure_test("expiry_too_soon", 0, &nodes, &route, &payment_hash, &payment_secret, |msg| {
let height = msg.cltv_expiry - CLTV_CLAIM_BUFFER - LATENCY_GRACE_PERIOD_BLOCKS + 1;
connect_blocks(&nodes[0], height - nodes[0].best_block_info().1);
connect_blocks(&nodes[1], height - nodes[1].best_block_info().1);
connect_blocks(&nodes[2], height - nodes[2].best_block_info().1);
}, ||{}, true, Some(UPDATE|14), Some(NetworkUpdate::ChannelUpdateMessage{msg: ChannelUpdate::dummy(short_channel_id)}), Some(short_channel_id));
}, ||{}, true, Some(UPDATE|14),
Some(NetworkUpdate::ChannelFailure { short_channel_id, is_permanent: false }),
Some(short_channel_id));

run_onion_failure_test("unknown_payment_hash", 2, &nodes, &route, &payment_hash, &payment_secret, |_| {}, || {
nodes[2].node.fail_htlc_backwards(&payment_hash);
Expand Down Expand Up @@ -596,7 +607,9 @@ fn test_onion_failure() {
// disconnect event to the channel between nodes[1] ~ nodes[2]
nodes[1].node.peer_disconnected(&nodes[2].node.get_our_node_id());
nodes[2].node.peer_disconnected(&nodes[1].node.get_our_node_id());
}, true, Some(UPDATE|7), Some(NetworkUpdate::ChannelUpdateMessage{msg: ChannelUpdate::dummy(short_channel_id)}), Some(short_channel_id));
}, true, Some(UPDATE|7),
Some(NetworkUpdate::ChannelFailure { short_channel_id, is_permanent: false }),
Some(short_channel_id));
run_onion_failure_test("channel_disabled", 0, &nodes, &route, &payment_hash, &payment_secret, |_| {}, || {
// disconnect event to the channel between nodes[1] ~ nodes[2]
for _ in 0..DISABLE_GOSSIP_TICKS + 1 {
Expand All @@ -605,7 +618,9 @@ fn test_onion_failure() {
}
nodes[1].node.get_and_clear_pending_msg_events();
nodes[2].node.get_and_clear_pending_msg_events();
}, true, Some(UPDATE|20), Some(NetworkUpdate::ChannelUpdateMessage{msg: ChannelUpdate::dummy(short_channel_id)}), Some(short_channel_id));
}, true, Some(UPDATE|20),
Some(NetworkUpdate::ChannelFailure { short_channel_id, is_permanent: false }),
Some(short_channel_id));
reconnect_nodes(ReconnectArgs::new(&nodes[1], &nodes[2]));

run_onion_failure_test("expiry_too_far", 0, &nodes, &route, &payment_hash, &payment_secret, |msg| {
Expand Down Expand Up @@ -844,9 +859,9 @@ fn do_test_onion_failure_stale_channel_update(announced_channel: bool) {
// We'll be attempting to route payments using the default ChannelUpdate for channels. This will
// lead to onion failures at the first hop once we update the ChannelConfig for the
// second hop.
let expect_onion_failure = |name: &str, error_code: u16, channel_update: &msgs::ChannelUpdate| {
let expect_onion_failure = |name: &str, error_code: u16| {
let short_channel_id = channel_to_update.1;
let network_update = NetworkUpdate::ChannelUpdateMessage { msg: channel_update.clone() };
let network_update = NetworkUpdate::ChannelFailure { short_channel_id, is_permanent: false };
run_onion_failure_test(
name, 0, &nodes, &route, &payment_hash, &payment_secret, |_| {}, || {}, true,
Some(error_code), Some(network_update), Some(short_channel_id),
Expand Down Expand Up @@ -878,7 +893,7 @@ fn do_test_onion_failure_stale_channel_update(announced_channel: bool) {
// Connect a block, which should expire the previous config, leading to a failure when
// forwarding the HTLC.
expire_prev_config();
expect_onion_failure("fee_insufficient", UPDATE|12, &msg);
expect_onion_failure("fee_insufficient", UPDATE|12);

// Redundant updates should not trigger a new ChannelUpdate.
assert!(update_and_get_channel_update(&config, false, None, false).is_none());
Expand All @@ -891,15 +906,15 @@ fn do_test_onion_failure_stale_channel_update(announced_channel: bool) {
// new ChannelUpdate.
config.forwarding_fee_base_msat = default_config.forwarding_fee_base_msat;
config.cltv_expiry_delta = u16::max_value();
let msg = update_and_get_channel_update(&config, true, Some(&msg), true).unwrap();
expect_onion_failure("incorrect_cltv_expiry", UPDATE|13, &msg);
assert!(update_and_get_channel_update(&config, true, Some(&msg), true).is_some());
expect_onion_failure("incorrect_cltv_expiry", UPDATE|13);

// Reset the proportional fee and increase the CLTV expiry delta which should trigger a new
// ChannelUpdate.
config.cltv_expiry_delta = default_config.cltv_expiry_delta;
config.forwarding_fee_proportional_millionths = u32::max_value();
let msg = update_and_get_channel_update(&config, true, Some(&msg), true).unwrap();
expect_onion_failure("fee_insufficient", UPDATE|12, &msg);
assert!(update_and_get_channel_update(&config, true, Some(&msg), true).is_some());
expect_onion_failure("fee_insufficient", UPDATE|12);

// To test persistence of the updated config, we'll re-initialize the ChannelManager.
let config_after_restart = {
Expand Down Expand Up @@ -1530,10 +1545,10 @@ fn do_test_phantom_dust_exposure_failure(multiplier_dust_limit: bool) {
err_data.extend_from_slice(&channel.1.encode());

let mut fail_conditions = PaymentFailedConditions::new()
.blamed_scid(channel.0.contents.short_channel_id)
.blamed_scid(route.paths[0].hops.last().as_ref().unwrap().short_channel_id)
.blamed_chan_closed(false)
.expected_htlc_error_data(0x1000 | 7, &err_data);
expect_payment_failed_conditions(&nodes[0], payment_hash, false, fail_conditions);
expect_payment_failed_conditions(&nodes[0], payment_hash, false, fail_conditions);
}

#[test]
Expand Down
105 changes: 7 additions & 98 deletions lightning/src/ln/onion_utils.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,6 @@ use crate::ln::channelmanager::{HTLCSource, RecipientOnionFields};
use crate::ln::features::{ChannelFeatures, NodeFeatures};
use crate::ln::msgs;
use crate::ln::types::{PaymentHash, PaymentPreimage};
use crate::ln::wire::Encode;
use crate::routing::gossip::NetworkUpdate;
use crate::routing::router::{Path, RouteHop, RouteParameters};
use crate::sign::NodeSigner;
Expand Down Expand Up @@ -806,106 +805,16 @@ where
{
let update_len =
u16::from_be_bytes(update_len_slice.try_into().expect("len is 2")) as usize;
if let Some(mut update_slice) = err_packet
if err_packet
.failuremsg
.get(debug_field_size + 4..debug_field_size + 4 + update_len)
.is_some()
{
// Historically, the BOLTs were unclear if the message type
// bytes should be included here or not. The BOLTs have now
// been updated to indicate that they *are* included, but many
// nodes still send messages without the type bytes, so we
// support both here.
// TODO: Switch to hard require the type prefix, as the current
// permissiveness introduces the (although small) possibility
// that we fail to decode legitimate channel updates that
// happen to start with ChannelUpdate::TYPE, i.e., [0x01, 0x02].
if update_slice.len() > 2
&& update_slice[0..2] == msgs::ChannelUpdate::TYPE.to_be_bytes()
{
update_slice = &update_slice[2..];
} else {
log_trace!(logger, "Failure provided features a channel update without type prefix. Deprecated, but allowing for now.");
}
let update_opt = msgs::ChannelUpdate::read(&mut Cursor::new(&update_slice));
if update_opt.is_ok() || update_slice.is_empty() {
// if channel_update should NOT have caused the failure:
// MAY treat the channel_update as invalid.
let is_chan_update_invalid = match error_code & 0xff {
7 => false,
11 => {
update_opt.is_ok()
&& amt_to_forward
> update_opt.as_ref().unwrap().contents.htlc_minimum_msat
},
12 => {
update_opt.is_ok()
&& amt_to_forward
.checked_mul(
update_opt
.as_ref()
.unwrap()
.contents
.fee_proportional_millionths as u64,
)
.map(|prop_fee| prop_fee / 1_000_000)
.and_then(|prop_fee| {
prop_fee.checked_add(
update_opt.as_ref().unwrap().contents.fee_base_msat
as u64,
)
})
.map(|fee_msats| route_hop.fee_msat >= fee_msats)
.unwrap_or(false)
},
13 => {
update_opt.is_ok()
&& route_hop.cltv_expiry_delta as u16
>= update_opt.as_ref().unwrap().contents.cltv_expiry_delta
},
14 => false, // expiry_too_soon; always valid?
20 => update_opt.as_ref().unwrap().contents.flags & 2 == 0,
_ => false, // unknown error code; take channel_update as valid
};
if is_chan_update_invalid {
// This probably indicates the node which forwarded
// to the node in question corrupted something.
network_update = Some(NetworkUpdate::ChannelFailure {
short_channel_id: route_hop.short_channel_id,
is_permanent: true,
});
} else {
if let Ok(chan_update) = update_opt {
// Make sure the ChannelUpdate contains the expected
// short channel id.
if failing_route_hop.short_channel_id
== chan_update.contents.short_channel_id
{
short_channel_id = Some(failing_route_hop.short_channel_id);
} else {
log_info!(logger, "Node provided a channel_update for which it was not authoritative, ignoring.");
}
network_update =
Some(NetworkUpdate::ChannelUpdateMessage { msg: chan_update })
} else {
// The node in question intentionally encoded a 0-length channel update. This is
// likely due to https://github.com/ElementsProject/lightning/issues/6200.
short_channel_id = Some(failing_route_hop.short_channel_id);
network_update = Some(NetworkUpdate::ChannelFailure {
short_channel_id: failing_route_hop.short_channel_id,
is_permanent: false,
});
}
};
} else {
// If the channel_update had a non-zero length (i.e. was
// present) but we couldn't read it, treat it as a total
// node failure.
log_info!(
logger,
"Failed to read a channel_update of len {} in an onion",
update_slice.len()
);
}
network_update = Some(NetworkUpdate::ChannelFailure {
short_channel_id: failing_route_hop.short_channel_id,
is_permanent: false,
});
short_channel_id = Some(failing_route_hop.short_channel_id);
}
}
if network_update.is_none() {
Expand Down

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