Ignore channel updates in onion errors.

Per <lightning/bolts#1163>.

Author: valentinewallace

lightning/src/ln/functional_test_utils.rs

@@ -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"),
 					}

lightning/src/ln/onion_route_tests.rs

@@ -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.
@@ -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();
@@ -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| {
@@ -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() {
@@ -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);
@@ -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 {
@@ -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| {
@@ -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),
@@ -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());
@@ -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 = {
@@ -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]

lightning/src/ln/onion_utils.rs

@@ -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;
@@ -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() {