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Fix PaymentPathFailed::payment_failed_permanently on blinded path fail #2576

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Merged
merged 6 commits into from
Sep 25, 2023
Merged

Fix PaymentPathFailed::payment_failed_permanently on blinded path fail #2576

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9ade8eb
Rename onion util internal var
valentinewallace Sep 14, 2023
61ab1f8
Struct-ify onion util internal result type
valentinewallace Sep 20, 2023
9c41f12
DecodedOnionFailure::payment_retryable -> ::payment_failed_permanently
valentinewallace Sep 14, 2023
5f5119f
Correct DecodedOnionFailure when processing we-are-intro-node path
valentinewallace Sep 14, 2023
9df61dc
Fix PaymentPathFailed::payment_failed_permanently on blinded path fail
valentinewallace Sep 14, 2023
6299f7d
Blame outbound channel on UPDATE onion failure with 0-len update
valentinewallace Sep 15, 2023
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30 changes: 28 additions & 2 deletions lightning/src/ln/onion_route_tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -645,8 +645,34 @@ fn test_onion_failure() {
}, || nodes[2].node.fail_htlc_backwards(&payment_hash), false, None,
Some(NetworkUpdate::NodeFailure { node_id: route.paths[0].hops[1].pubkey, is_permanent: true }),
Some(channels[1].0.contents.short_channel_id));
run_onion_failure_test_with_fail_intercept("0-length channel update in UPDATE onion failure", 200, &nodes,
&route, &payment_hash, &payment_secret, |_msg| {}, |msg| {
run_onion_failure_test_with_fail_intercept("0-length channel update in intermediate node UPDATE onion failure",
100, &nodes, &route, &payment_hash, &payment_secret, |msg| {
msg.amount_msat -= 1;
}, |msg| {
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();
let mut decoded_err_packet = msgs::DecodedOnionErrorPacket {
failuremsg: vec![
0x10, 0x7, // UPDATE|7
0x0, 0x0 // 0-len channel update
],
pad: vec![0; 255 - 4 /* 4-byte error message */],
hmac: [0; 32],
};
let um = onion_utils::gen_um_from_shared_secret(&onion_keys[0].shared_secret.as_ref());
let mut hmac = HmacEngine::<Sha256>::new(&um);
hmac.input(&decoded_err_packet.encode()[32..]);
decoded_err_packet.hmac = Hmac::from_engine(hmac).into_inner();
msg.reason = onion_utils::encrypt_failure_packet(
&onion_keys[0].shared_secret.as_ref(), &decoded_err_packet.encode()[..])
}, || {}, true, Some(0x1000|7),
Some(NetworkUpdate::ChannelFailure {
short_channel_id: channels[1].0.contents.short_channel_id,
is_permanent: false,
}),
Some(channels[1].0.contents.short_channel_id));
run_onion_failure_test_with_fail_intercept("0-length channel update in final node UPDATE onion failure",
200, &nodes, &route, &payment_hash, &payment_secret, |_msg| {}, |msg| {
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();
let mut decoded_err_packet = msgs::DecodedOnionErrorPacket {
Expand Down
62 changes: 47 additions & 15 deletions lightning/src/ln/onion_utils.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -426,7 +426,7 @@ pub(super) fn build_first_hop_failure_packet(shared_secret: &[u8], failure_type:
pub(crate) struct DecodedOnionFailure {
pub(crate) network_update: Option<NetworkUpdate>,
pub(crate) short_channel_id: Option<u64>,
pub(crate) payment_retryable: bool,
pub(crate) payment_failed_permanently: bool,
#[cfg(test)]
pub(crate) onion_error_code: Option<u16>,
#[cfg(test)]
Expand All @@ -444,7 +444,14 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(
} = htlc_source {
(path, session_priv, first_hop_htlc_msat)
} else { unreachable!() };
let mut res = None;

// Learnings from the HTLC failure to inform future payment retries and scoring.
struct FailureLearnings {
network_update: Option<NetworkUpdate>,
short_channel_id: Option<u64>,
payment_failed_permanently: bool,
}
let mut res: Option<FailureLearnings> = None;
let mut htlc_msat = *first_hop_htlc_msat;
let mut error_code_ret = None;
let mut error_packet_ret = None;
Expand All @@ -467,11 +474,33 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(
// Got an error from within a blinded route.
error_code_ret = Some(BADONION | PERM | 24); // invalid_onion_blinding
error_packet_ret = Some(vec![0; 32]);
is_from_final_node = false;
res = Some(FailureLearnings {
network_update: None, short_channel_id: None, payment_failed_permanently: false
});
return
},
};

// The failing hop includes either the inbound channel to the recipient or the outbound channel
// from the current hop (i.e., the next hop's inbound channel).
let num_blinded_hops = path.blinded_tail.as_ref().map_or(0, |bt| bt.hops.len());
// For 1-hop blinded paths, the final `path.hops` entry is the recipient.
is_from_final_node = route_hop_idx + 1 == path.hops.len() && num_blinded_hops <= 1;
let failing_route_hop = if is_from_final_node { route_hop } else {
match path.hops.get(route_hop_idx + 1) {
Some(hop) => hop,
None => {
// The failing hop is within a multi-hop blinded path.
error_code_ret = Some(BADONION | PERM | 24); // invalid_onion_blinding
error_packet_ret = Some(vec![0; 32]);
res = Some(FailureLearnings {
network_update: None, short_channel_id: None, payment_failed_permanently: false
});
return
}
}
};

let amt_to_forward = htlc_msat - route_hop.fee_msat;
htlc_msat = amt_to_forward;

Expand All @@ -483,11 +512,6 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(
chacha.process(&packet_decrypted, &mut decryption_tmp[..]);
packet_decrypted = decryption_tmp;

// The failing hop includes either the inbound channel to the recipient or the outbound channel
// from the current hop (i.e., the next hop's inbound channel).
is_from_final_node = route_hop_idx + 1 == path.hops.len();
let failing_route_hop = if is_from_final_node { route_hop } else { &path.hops[route_hop_idx + 1] };

let err_packet = match msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(&packet_decrypted)) {
Ok(p) => p,
Err(_) => return
Expand All @@ -507,7 +531,9 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(
is_permanent: true,
});
let short_channel_id = Some(route_hop.short_channel_id);
res = Some((network_update, short_channel_id, !is_from_final_node));
res = Some(FailureLearnings {
network_update, short_channel_id, payment_failed_permanently: is_from_final_node
});
return
}
};
Expand Down Expand Up @@ -615,8 +641,9 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(
} 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: route_hop.short_channel_id,
short_channel_id: failing_route_hop.short_channel_id,
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We should remove the network update entirely. Even with perm set to false this will still mark the channel disabled even though it isn't.

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@valentinewallace valentinewallace Sep 20, 2023 •
edited
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We only mark the channel as disabled if is_permanent is set. It's nice to set it because then we can more easily keep the behavior of defaulting to NetworkUpdate::NodeFailure on a totally bogus channel update.

is_permanent: false,
});
}
Expand Down Expand Up @@ -659,7 +686,10 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(
short_channel_id = Some(route_hop.short_channel_id);
}

res = Some((network_update, short_channel_id, !(error_code & PERM == PERM && is_from_final_node)));
res = Some(FailureLearnings {
network_update, short_channel_id,
payment_failed_permanently: error_code & PERM == PERM && is_from_final_node
});

let (description, title) = errors::get_onion_error_description(error_code);
if debug_field_size > 0 && err_packet.failuremsg.len() >= 4 + debug_field_size {
Expand All @@ -668,9 +698,11 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(
log_info!(logger, "Onion Error[from {}: {}({:#x})] {}", route_hop.pubkey, title, error_code, description);
}
}).expect("Route that we sent via spontaneously grew invalid keys in the middle of it?");
if let Some((network_update, short_channel_id, payment_retryable)) = res {
if let Some(FailureLearnings {
network_update, short_channel_id, payment_failed_permanently
}) = res {
DecodedOnionFailure {
network_update, short_channel_id, payment_retryable,
network_update, short_channel_id, payment_failed_permanently,
#[cfg(test)]
onion_error_code: error_code_ret,
#[cfg(test)]
Expand All @@ -680,7 +712,7 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(
// only not set either packet unparseable or hmac does not match with any
// payment not retryable only when garbage is from the final node
DecodedOnionFailure {
network_update: None, short_channel_id: None, payment_retryable: !is_from_final_node,
network_update: None, short_channel_id: None, payment_failed_permanently: is_from_final_node,
#[cfg(test)]
onion_error_code: None,
#[cfg(test)]
Expand Down Expand Up @@ -824,7 +856,7 @@ impl HTLCFailReason {
if let &HTLCSource::OutboundRoute { ref path, .. } = htlc_source {
DecodedOnionFailure {
network_update: None,
payment_retryable: true,
payment_failed_permanently: false,
short_channel_id: Some(path.hops[0].short_channel_id),
#[cfg(test)]
onion_error_code: Some(*failure_code),
Expand Down
13 changes: 7 additions & 6 deletions lightning/src/ln/outbound_payment.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1484,10 +1484,11 @@ impl OutboundPayments {
) -> bool where L::Target: Logger {
#[cfg(test)]
let DecodedOnionFailure {
network_update, short_channel_id, payment_retryable, onion_error_code, onion_error_data
network_update, short_channel_id, payment_failed_permanently, onion_error_code,
onion_error_data
} = onion_error.decode_onion_failure(secp_ctx, logger, &source);
#[cfg(not(test))]
let DecodedOnionFailure { network_update, short_channel_id, payment_retryable } =
let DecodedOnionFailure { network_update, short_channel_id, payment_failed_permanently } =
onion_error.decode_onion_failure(secp_ctx, logger, &source);

let payment_is_probe = payment_is_probe(payment_hash, &payment_id, probing_cookie_secret);
Expand Down Expand Up @@ -1528,8 +1529,8 @@ impl OutboundPayments {
payment.get_mut().insert_previously_failed_scid(scid);
}

if payment_is_probe || !is_retryable_now || !payment_retryable {
let reason = if !payment_retryable {
if payment_is_probe || !is_retryable_now || payment_failed_permanently {
let reason = if payment_failed_permanently {
PaymentFailureReason::RecipientRejected
} else {
PaymentFailureReason::RetriesExhausted
Expand Down Expand Up @@ -1559,7 +1560,7 @@ impl OutboundPayments {

let path_failure = {
if payment_is_probe {
if !payment_retryable {
if payment_failed_permanently {
events::Event::ProbeSuccessful {
payment_id: *payment_id,
payment_hash: payment_hash.clone(),
Expand All @@ -1583,7 +1584,7 @@ impl OutboundPayments {
events::Event::PaymentPathFailed {
payment_id: Some(*payment_id),
payment_hash: payment_hash.clone(),
payment_failed_permanently: !payment_retryable,
payment_failed_permanently,
failure: events::PathFailure::OnPath { network_update },
path: path.clone(),
short_channel_id,
Expand Down