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Merged
arik-so merged 4 commits into from
Mar 4, 2025
Merged

Log cases where an onion failure cannot be attributed or interpreted #3629

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447148d
Add test coverage for process_onion_failure
joostjager Feb 28, 2025
f307ab7
Remove error side effect from decrypt_onion_error_packet
joostjager Mar 3, 2025
00f42de
Log cases where an onion failure cannot be attributed or interpreted
joostjager Feb 28, 2025
f38244c
Properly attribute unreadable failures with a valid hmac
joostjager Feb 28, 2025
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277 changes: 232 additions & 45 deletions lightning/src/ln/onion_utils.rs
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Original file line numberDiff line numberDiff line change
Expand Up@@ -931,15 +931,11 @@ pub(crate) struct DecodedOnionFailure {
pub(crate) onion_error_data: Option<Vec<u8>>,
}

/// Note that we always decrypt `packet` in-place here even if the deserialization into
/// [`msgs::DecodedOnionErrorPacket`] ultimately fails.
fn decrypt_onion_error_packet(
packet: &mut Vec<u8>, shared_secret: SharedSecret,
) -> Result<msgs::DecodedOnionErrorPacket, msgs::DecodeError> {
/// Decrypt the error packet in-place.
fn decrypt_onion_error_packet(packet: &mut Vec<u8>, shared_secret: SharedSecret) {

@arik-soarik-soMar 4, 2025

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I almost wonder whether it's one of those instances where in-place processing is what largely contributes to confusion. Getting a result back with the decrypted packet or with the decryption error, without worrying about the input argument getting changed, seems preferable.

@joostjagerjoostjagerMar 4, 2025

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The confusion was mainly that this used to be a function that returned a value and still had a side effect too. A side effect that was also needed, because the decrypted packet needs to be processed for the next hop.

Could have returned a decrypted copy in addition to the decoded failure to make it a pure function, probably with some performance implications. But I think now that this function has no return value anymore and only decrypts in-place, it's already a lot better.

let ammag = gen_ammag_from_shared_secret(shared_secret.as_ref());
let mut chacha = ChaCha20::new(&ammag, &[0u8; 8]);
chacha.process_in_place(packet);
msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(packet))
}

/// Process failure we got back from upstream on a payment we sent (implying htlc_source is an
Expand DownExpand Up@@ -1021,9 +1017,11 @@ where
{
// Actually parse the onion error data in tests so we can check that blinded hops fail
// back correctly.
let err_packet =
decrypt_onion_error_packet(&mut encrypted_packet, shared_secret)
.unwrap();
decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);
let err_packet = msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(
&encrypted_packet,
))
.unwrap();
error_code_ret = Some(u16::from_be_bytes(
err_packet.failuremsg.get(0..2).unwrap().try_into().unwrap(),
));
Expand All@@ -1044,22 +1042,44 @@ where
let amt_to_forward = htlc_msat - route_hop.fee_msat;
htlc_msat = amt_to_forward;

let err_packet = match decrypt_onion_error_packet(&mut encrypted_packet, shared_secret) {
Ok(p) => p,
Err(_) => return,
};
decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);

let um = gen_um_from_shared_secret(shared_secret.as_ref());
let mut hmac = HmacEngine::<Sha256>::new(&um);
hmac.input(&err_packet.encode()[32..]);
hmac.input(&encrypted_packet[32..]);

if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &err_packet.hmac) {
if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &encrypted_packet[..32]) {
return;
}

let err_packet =
match msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(&encrypted_packet)) {
Ok(p) => p,
Err(_) => {
log_warn!(logger, "Unreadable failure from {}", route_hop.pubkey);

let network_update = Some(NetworkUpdate::NodeFailure {
node_id: route_hop.pubkey,
is_permanent: true,
});
let short_channel_id = Some(route_hop.short_channel_id);
res = Some(FailureLearnings {
network_update,
short_channel_id,
payment_failed_permanently: is_from_final_node,
failed_within_blinded_path: false,
});
return;
},
};

let error_code_slice = match err_packet.failuremsg.get(0..2) {
Some(s) => s,
None => {
// Useless packet that we can't use but it passed HMAC, so it definitely came from the peer
// in question
log_warn!(logger, "Missing error code in failure from {}", route_hop.pubkey);

let network_update = Some(NetworkUpdate::NodeFailure {
node_id: route_hop.pubkey,
is_permanent: true,
Expand DownExpand Up@@ -1219,6 +1239,12 @@ where
} else {
// only not set either packet unparseable or hmac does not match with any
// payment not retryable only when garbage is from the final node
log_warn!(
logger,
"Non-attributable failure encountered on route {}",
path.hops.iter().map(|h| h.pubkey.to_string()).collect::<Vec<_>>().join("->")
);

DecodedOnionFailure {
network_update: None,
short_channel_id: None,
Expand DownExpand Up@@ -1764,7 +1790,10 @@ fn decode_next_hop<T, R: ReadableArgs<T>, N: NextPacketBytes>(

#[cfg(test)]
mod tests {
use std::sync::Arc;

use crate::io;
use crate::ln::channelmanager::PaymentId;
use crate::ln::msgs;
use crate::routing::router::{Path, PaymentParameters, Route, RouteHop};
use crate::types::features::{ChannelFeatures, NodeFeatures};
Expand All@@ -1773,6 +1802,7 @@ mod tests {

#[allow(unused_imports)]
use crate::prelude::*;
use crate::util::test_utils::TestLogger;

use bitcoin::hex::FromHex;
use bitcoin::secp256k1::Secp256k1;
Expand All@@ -1785,40 +1815,95 @@ mod tests {
SecretKey::from_slice(&<Vec<u8>>::from_hex(hex).unwrap()[..]).unwrap()
}

fn build_test_path() -> Path {
Path {
hops: vec![
RouteHop {

@joostjagerjoostjagerFeb 28, 2025

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rustfmt wanted this

pubkey: PublicKey::from_slice(
&<Vec<u8>>::from_hex(
"02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619",
)
.unwrap()[..],
)
.unwrap(),
channel_features: ChannelFeatures::empty(),
node_features: NodeFeatures::empty(),
short_channel_id: 0,
fee_msat: 0,
cltv_expiry_delta: 0,
maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
},
RouteHop {
pubkey: PublicKey::from_slice(
&<Vec<u8>>::from_hex(
"0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c",
)
.unwrap()[..],
)
.unwrap(),
channel_features: ChannelFeatures::empty(),
node_features: NodeFeatures::empty(),
short_channel_id: 1,

@joostjagerjoostjagerFeb 28, 2025

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it is a move, but just these short_channel_id's made unique to make it easier to test things for attr errors

fee_msat: 0,
cltv_expiry_delta: 0,
maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
},
RouteHop {
pubkey: PublicKey::from_slice(
&<Vec<u8>>::from_hex(
"027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007",
)
.unwrap()[..],
)
.unwrap(),
channel_features: ChannelFeatures::empty(),
node_features: NodeFeatures::empty(),
short_channel_id: 2,
fee_msat: 0,
cltv_expiry_delta: 0,
maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
},
RouteHop {
pubkey: PublicKey::from_slice(
&<Vec<u8>>::from_hex(
"032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991",
)
.unwrap()[..],
)
.unwrap(),
channel_features: ChannelFeatures::empty(),
node_features: NodeFeatures::empty(),
short_channel_id: 3,
fee_msat: 0,
cltv_expiry_delta: 0,
maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
},
RouteHop {
pubkey: PublicKey::from_slice(
&<Vec<u8>>::from_hex(
"02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145",
)
.unwrap()[..],
)
.unwrap(),
channel_features: ChannelFeatures::empty(),
node_features: NodeFeatures::empty(),
short_channel_id: 4,
fee_msat: 0,
cltv_expiry_delta: 0,
maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
},
],
blinded_tail: None,
}
}

fn build_test_onion_keys() -> Vec<OnionKeys> {
// Keys from BOLT 4, used in both test vector tests
let secp_ctx = Secp256k1::new();

let route = Route {
paths: vec![Path { hops: vec![
RouteHop {
pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
},
RouteHop {
pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
},
RouteHop {
pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
},
RouteHop {
pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991").unwrap()[..]).unwrap(),
channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
},
RouteHop {
pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145").unwrap()[..]).unwrap(),
channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
},
], blinded_tail: None }],
route_params: None,
};
let path = build_test_path();
let route = Route { paths: vec![path], route_params: None };

let onion_keys =
super::construct_onion_keys(&secp_ctx, &route.paths[0], &get_test_session_key())
Expand DownExpand Up@@ -2078,6 +2163,108 @@ mod tests {
);
let hex = "9c5add3963fc7f6ed7f148623c84134b5647e1306419dbe2174e523fa9e2fbed3a06a19f899145610741c83ad40b7712aefaddec8c6baf7325d92ea4ca4d1df8bce517f7e54554608bf2bd8071a4f52a7a2f7ffbb1413edad81eeea5785aa9d990f2865dc23b4bc3c301a94eec4eabebca66be5cf638f693ec256aec514620cc28ee4a94bd9565bc4d4962b9d3641d4278fb319ed2b84de5b665f307a2db0f7fbb757366067d88c50f7e829138fde4f78d39b5b5802f1b92a8a820865af5cc79f9f30bc3f461c66af95d13e5e1f0381c184572a91dee1c849048a647a1158cf884064deddbf1b0b88dfe2f791428d0ba0f6fb2f04e14081f69165ae66d9297c118f0907705c9c4954a199bae0bb96fad763d690e7daa6cfda59ba7f2c8d11448b604d12d";
assert_eq!(onion_packet_5.data, <Vec<u8>>::from_hex(hex).unwrap());

let logger: Arc<TestLogger> = Arc::new(TestLogger::new());
let ctx_full = Secp256k1::new();
let path = build_test_path();
let htlc_source = HTLCSource::OutboundRoute {
path,
session_priv: get_test_session_key(),
first_hop_htlc_msat: 0,
payment_id: PaymentId([1; 32]),
};

// Assert that the original failure can be retrieved and that all hmacs check out.
let decrypted_failure =
process_onion_failure(&ctx_full, &logger, &htlc_source, onion_packet_5.data);

assert_eq!(decrypted_failure.onion_error_code, Some(0x2002));
}

#[test]
fn test_non_attributable_failure_packet_onion() {
// Create a failure packet with bogus data.
let packet = vec![1u8; 292];

// In the current protocol, it is unfortunately not possible to identify the failure source.
let logger: TestLogger = TestLogger::new();
let decrypted_failure = test_failure_attribution(&logger, &packet);
assert_eq!(decrypted_failure.short_channel_id, None);

logger.assert_log_contains(
"lightning::ln::onion_utils",
"Non-attributable failure encountered",
1,
);
}

#[test]
fn test_unreadable_failure_packet_onion() {
// Create a failure packet with a valid hmac but unreadable failure message.
let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
let shared_secret = onion_keys[0].shared_secret.as_ref();
let um = gen_um_from_shared_secret(&shared_secret);

// The failure message is a single 0 byte.
let mut packet = [0u8; 33];

let mut hmac = HmacEngine::<Sha256>::new(&um);
hmac.input(&packet[32..]);
let hmac = Hmac::from_engine(hmac).to_byte_array();
packet[..32].copy_from_slice(&hmac);

let packet = encrypt_failure_packet(shared_secret, &packet);

// For the unreadable failure, it is still expected that the failing channel can be identified.
let logger: TestLogger = TestLogger::new();
let decrypted_failure = test_failure_attribution(&logger, &packet.data);
assert_eq!(decrypted_failure.short_channel_id, Some(0));

logger.assert_log_contains("lightning::ln::onion_utils", "Unreadable failure", 1);
}

#[test]
fn test_missing_error_code() {
// Create a failure packet with a valid hmac and structure, but no error code.
let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
let shared_secret = onion_keys[0].shared_secret.as_ref();
let um = gen_um_from_shared_secret(&shared_secret);

let failuremsg = vec![1];
let pad = Vec::new();
let mut packet = msgs::DecodedOnionErrorPacket { hmac: [0; 32], failuremsg, pad };

let mut hmac = HmacEngine::<Sha256>::new(&um);
hmac.input(&packet.encode()[32..]);
packet.hmac = Hmac::from_engine(hmac).to_byte_array();

let packet = encrypt_failure_packet(shared_secret, &packet.encode()[..]);

let logger = TestLogger::new();
let decrypted_failure = test_failure_attribution(&logger, &packet.data);
assert_eq!(decrypted_failure.short_channel_id, Some(0));

logger.assert_log_contains(
"lightning::ln::onion_utils",
"Missing error code in failure",
1,
);
}

fn test_failure_attribution(logger: &TestLogger, packet: &[u8]) -> DecodedOnionFailure {
let ctx_full = Secp256k1::new();
let path = build_test_path();
let htlc_source = HTLCSource::OutboundRoute {
path,
session_priv: get_test_session_key(),
first_hop_htlc_msat: 0,
payment_id: PaymentId([1; 32]),
};

let decrypted_failure =
process_onion_failure(&ctx_full, &logger, &htlc_source, packet.into());

decrypted_failure
}

struct RawOnionHopData {
Expand Down
, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
 blocks
(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
};
codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
Log cases where an onion failure cannot be attributed or interpreted by joostjager · Pull Request #3629 · lightningdevkit/rust-lightning · GitHub
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Log cases where an onion failure cannot be attributed or interpreted#3629

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 Merged

arik-so
merged 4 commits into

from

Mar 4, 2025
 Merged


Log cases where an onion failure cannot be attributed or interpreted
#3629
 Changes from all commits
Commits

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4 commits


Select commit
Hold shift + click to select a range
447148d

Add test coverage for process_onion_failure


joostjager Feb 28, 2025
f307ab7

Remove error side effect from decrypt_onion_error_packet


joostjager Mar 3, 2025
00f42de

Log cases where an onion failure cannot be attributed or interpreted


joostjager Feb 28, 2025
f38244c

Properly attribute unreadable failures with a valid hmac


joostjager Feb 28, 2025

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277 changes: 232 additions & 45 deletions
lightning/src/ln/onion_utils.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -931,15 +931,11 @@ pub(crate) struct DecodedOnionFailure {
	pub(crate) onion_error_data: Option<Vec<u8>>,
}

/// Note that we always decrypt `packet` in-place here even if the deserialization into
/// [`msgs::DecodedOnionErrorPacket`] ultimately fails.
fn decrypt_onion_error_packet(
	packet: &mut Vec<u8>, shared_secret: SharedSecret,
) -> Result<msgs::DecodedOnionErrorPacket, msgs::DecodeError> {
/// Decrypt the error packet in-place.
fn decrypt_onion_error_packet(packet: &mut Vec<u8>, shared_secret: SharedSecret) {
@arik-soarik-soMar 4, 2025

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I almost wonder whether it's one of those instances where in-place processing is what largely contributes to confusion. Getting a result back with the decrypted packet or with the decryption error, without worrying about the input argument getting changed, seems preferable.
@joostjagerjoostjagerMar 4, 2025

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The confusion was mainly that this used to be a function that returned a value and still had a side effect too. A side effect that was also needed, because the decrypted packet needs to be processed for the next hop.
Could have returned a decrypted copy in addition to the decoded failure to make it a pure function, probably with some performance implications. But I think now that this function has no return value anymore and only decrypts in-place, it's already a lot better.
	let ammag = gen_ammag_from_shared_secret(shared_secret.as_ref());
	let mut chacha = ChaCha20::new(&ammag, &[0u8; 8]);
	chacha.process_in_place(packet);
	msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(packet))
}

/// Process failure we got back from upstream on a payment we sent (implying htlc_source is an
Expand DownExpand Up@@ -1021,9 +1017,11 @@ where
 {
 // Actually parse the onion error data in tests so we can check that blinded hops fail
 // back correctly.
 let err_packet =
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret)
 .unwrap();
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);
 let err_packet = msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(
 &encrypted_packet,
 ))
 .unwrap();
 error_code_ret = Some(u16::from_be_bytes(
 err_packet.failuremsg.get(0..2).unwrap().try_into().unwrap(),
 ));
Expand All@@ -1044,22 +1042,44 @@ where
 let amt_to_forward = htlc_msat - route_hop.fee_msat;
 htlc_msat = amt_to_forward;

 let err_packet = match decrypt_onion_error_packet(&mut encrypted_packet, shared_secret) {
 Ok(p) => p,
 Err(_) => return,
 };
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);

 let um = gen_um_from_shared_secret(shared_secret.as_ref());
 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&err_packet.encode()[32..]);
 hmac.input(&encrypted_packet[32..]);

 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &err_packet.hmac) {
 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &encrypted_packet[..32]) {
 return;
 }

 let err_packet =
 match msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(&encrypted_packet)) {
 Ok(p) => p,
 Err(_) => {
 log_warn!(logger, "Unreadable failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
 });
 let short_channel_id = Some(route_hop.short_channel_id);
 res = Some(FailureLearnings {
 network_update,
 short_channel_id,
 payment_failed_permanently: is_from_final_node,
 failed_within_blinded_path: false,
 });
 return;
 },
 };

 let error_code_slice = match err_packet.failuremsg.get(0..2) {
 Some(s) => s,
 None => {
 // Useless packet that we can't use but it passed HMAC, so it definitely came from the peer
 // in question
 log_warn!(logger, "Missing error code in failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
Expand DownExpand Up@@ -1219,6 +1239,12 @@ where
	} else {
 // only not set either packet unparseable or hmac does not match with any
 // payment not retryable only when garbage is from the final node
 log_warn!(
 logger,
 "Non-attributable failure encountered on route {}",
 path.hops.iter().map(|h| h.pubkey.to_string()).collect::<Vec<_>>().join("->")
 );

 DecodedOnionFailure {
 network_update: None,
 short_channel_id: None,
Expand DownExpand Up@@ -1764,7 +1790,10 @@ fn decode_next_hop<T, R: ReadableArgs<T>, N: NextPacketBytes>(

#[cfg(test)]
mod tests {
	use std::sync::Arc;

	use crate::io;
	use crate::ln::channelmanager::PaymentId;
	use crate::ln::msgs;
	use crate::routing::router::{Path, PaymentParameters, Route, RouteHop};
	use crate::types::features::{ChannelFeatures, NodeFeatures};
Expand All@@ -1773,6 +1802,7 @@ mod tests {

	#[allow(unused_imports)]
	use crate::prelude::*;
	use crate::util::test_utils::TestLogger;

	use bitcoin::hex::FromHex;
	use bitcoin::secp256k1::Secp256k1;
Expand All@@ -1785,40 +1815,95 @@ mod tests {
 SecretKey::from_slice(&<Vec<u8>>::from_hex(hex).unwrap()[..]).unwrap()
	}

	fn build_test_path() -> Path {
 Path {
 hops: vec![
 RouteHop {
@joostjagerjoostjagerFeb 28, 2025

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rustfmt wanted this
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 0,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 1,
@joostjagerjoostjagerFeb 28, 2025

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it is a move, but just these short_channel_id's made unique to make it easier to test things for attr errors
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 2,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 3,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 4,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ],
 blinded_tail: None,
 }
	}

	fn build_test_onion_keys() -> Vec<OnionKeys> {
 // Keys from BOLT 4, used in both test vector tests
 let secp_ctx = Secp256k1::new();

 let route = Route {
 paths: vec![Path { hops: vec![
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ], blinded_tail: None }],
 route_params: None,
 };
 let path = build_test_path();
 let route = Route { paths: vec![path], route_params: None };

 let onion_keys =
 super::construct_onion_keys(&secp_ctx, &route.paths[0], &get_test_session_key())
Expand DownExpand Up@@ -2078,6 +2163,108 @@ mod tests {
 );
 let hex = "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";
 assert_eq!(onion_packet_5.data, <Vec<u8>>::from_hex(hex).unwrap());

 let logger: Arc<TestLogger> = Arc::new(TestLogger::new());
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 // Assert that the original failure can be retrieved and that all hmacs check out.
 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, onion_packet_5.data);

 assert_eq!(decrypted_failure.onion_error_code, Some(0x2002));
	}

	#[test]
	fn test_non_attributable_failure_packet_onion() {
 // Create a failure packet with bogus data.
 let packet = vec![1u8; 292];

 // In the current protocol, it is unfortunately not possible to identify the failure source.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet);
 assert_eq!(decrypted_failure.short_channel_id, None);

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Non-attributable failure encountered",
 1,
 );
	}

	#[test]
	fn test_unreadable_failure_packet_onion() {
 // Create a failure packet with a valid hmac but unreadable failure message.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 // The failure message is a single 0 byte.
 let mut packet = [0u8; 33];

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet[32..]);
 let hmac = Hmac::from_engine(hmac).to_byte_array();
 packet[..32].copy_from_slice(&hmac);

 let packet = encrypt_failure_packet(shared_secret, &packet);

 // For the unreadable failure, it is still expected that the failing channel can be identified.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains("lightning::ln::onion_utils", "Unreadable failure", 1);
	}

	#[test]
	fn test_missing_error_code() {
 // Create a failure packet with a valid hmac and structure, but no error code.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 let failuremsg = vec![1];
 let pad = Vec::new();
 let mut packet = msgs::DecodedOnionErrorPacket { hmac: [0; 32], failuremsg, pad };

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet.encode()[32..]);
 packet.hmac = Hmac::from_engine(hmac).to_byte_array();

 let packet = encrypt_failure_packet(shared_secret, &packet.encode()[..]);

 let logger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Missing error code in failure",
 1,
 );
	}

	fn test_failure_attribution(logger: &TestLogger, packet: &[u8]) -> DecodedOnionFailure {
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, packet.into());

 decrypted_failure
	}

	struct RawOnionHopData {
Expand Down

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color-scheme: dark light;
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Log cases where an onion failure cannot be attributed or interpreted by joostjager · Pull Request #3629 · lightningdevkit/rust-lightning · GitHub
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 Merged

arik-so
merged 4 commits into

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Mar 4, 2025
 Merged


Log cases where an onion failure cannot be attributed or interpreted
#3629
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447148d

Add test coverage for process_onion_failure


joostjager Feb 28, 2025
f307ab7

Remove error side effect from decrypt_onion_error_packet


joostjager Mar 3, 2025
00f42de

Log cases where an onion failure cannot be attributed or interpreted


joostjager Feb 28, 2025
f38244c

Properly attribute unreadable failures with a valid hmac


joostjager Feb 28, 2025

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277 changes: 232 additions & 45 deletions
lightning/src/ln/onion_utils.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -931,15 +931,11 @@ pub(crate) struct DecodedOnionFailure {
	pub(crate) onion_error_data: Option<Vec<u8>>,
}

/// Note that we always decrypt `packet` in-place here even if the deserialization into
/// [`msgs::DecodedOnionErrorPacket`] ultimately fails.
fn decrypt_onion_error_packet(
	packet: &mut Vec<u8>, shared_secret: SharedSecret,
) -> Result<msgs::DecodedOnionErrorPacket, msgs::DecodeError> {
/// Decrypt the error packet in-place.
fn decrypt_onion_error_packet(packet: &mut Vec<u8>, shared_secret: SharedSecret) {
@arik-soarik-soMar 4, 2025

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I almost wonder whether it's one of those instances where in-place processing is what largely contributes to confusion. Getting a result back with the decrypted packet or with the decryption error, without worrying about the input argument getting changed, seems preferable.
@joostjagerjoostjagerMar 4, 2025

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The confusion was mainly that this used to be a function that returned a value and still had a side effect too. A side effect that was also needed, because the decrypted packet needs to be processed for the next hop.
Could have returned a decrypted copy in addition to the decoded failure to make it a pure function, probably with some performance implications. But I think now that this function has no return value anymore and only decrypts in-place, it's already a lot better.
	let ammag = gen_ammag_from_shared_secret(shared_secret.as_ref());
	let mut chacha = ChaCha20::new(&ammag, &[0u8; 8]);
	chacha.process_in_place(packet);
	msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(packet))
}

/// Process failure we got back from upstream on a payment we sent (implying htlc_source is an
Expand DownExpand Up@@ -1021,9 +1017,11 @@ where
 {
 // Actually parse the onion error data in tests so we can check that blinded hops fail
 // back correctly.
 let err_packet =
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret)
 .unwrap();
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);
 let err_packet = msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(
 &encrypted_packet,
 ))
 .unwrap();
 error_code_ret = Some(u16::from_be_bytes(
 err_packet.failuremsg.get(0..2).unwrap().try_into().unwrap(),
 ));
Expand All@@ -1044,22 +1042,44 @@ where
 let amt_to_forward = htlc_msat - route_hop.fee_msat;
 htlc_msat = amt_to_forward;

 let err_packet = match decrypt_onion_error_packet(&mut encrypted_packet, shared_secret) {
 Ok(p) => p,
 Err(_) => return,
 };
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);

 let um = gen_um_from_shared_secret(shared_secret.as_ref());
 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&err_packet.encode()[32..]);
 hmac.input(&encrypted_packet[32..]);

 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &err_packet.hmac) {
 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &encrypted_packet[..32]) {
 return;
 }

 let err_packet =
 match msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(&encrypted_packet)) {
 Ok(p) => p,
 Err(_) => {
 log_warn!(logger, "Unreadable failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
 });
 let short_channel_id = Some(route_hop.short_channel_id);
 res = Some(FailureLearnings {
 network_update,
 short_channel_id,
 payment_failed_permanently: is_from_final_node,
 failed_within_blinded_path: false,
 });
 return;
 },
 };

 let error_code_slice = match err_packet.failuremsg.get(0..2) {
 Some(s) => s,
 None => {
 // Useless packet that we can't use but it passed HMAC, so it definitely came from the peer
 // in question
 log_warn!(logger, "Missing error code in failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
Expand DownExpand Up@@ -1219,6 +1239,12 @@ where
	} else {
 // only not set either packet unparseable or hmac does not match with any
 // payment not retryable only when garbage is from the final node
 log_warn!(
 logger,
 "Non-attributable failure encountered on route {}",
 path.hops.iter().map(|h| h.pubkey.to_string()).collect::<Vec<_>>().join("->")
 );

 DecodedOnionFailure {
 network_update: None,
 short_channel_id: None,
Expand DownExpand Up@@ -1764,7 +1790,10 @@ fn decode_next_hop<T, R: ReadableArgs<T>, N: NextPacketBytes>(

#[cfg(test)]
mod tests {
	use std::sync::Arc;

	use crate::io;
	use crate::ln::channelmanager::PaymentId;
	use crate::ln::msgs;
	use crate::routing::router::{Path, PaymentParameters, Route, RouteHop};
	use crate::types::features::{ChannelFeatures, NodeFeatures};
Expand All@@ -1773,6 +1802,7 @@ mod tests {

	#[allow(unused_imports)]
	use crate::prelude::*;
	use crate::util::test_utils::TestLogger;

	use bitcoin::hex::FromHex;
	use bitcoin::secp256k1::Secp256k1;
Expand All@@ -1785,40 +1815,95 @@ mod tests {
 SecretKey::from_slice(&<Vec<u8>>::from_hex(hex).unwrap()[..]).unwrap()
	}

	fn build_test_path() -> Path {
 Path {
 hops: vec![
 RouteHop {
@joostjagerjoostjagerFeb 28, 2025

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rustfmt wanted this
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 0,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 1,
@joostjagerjoostjagerFeb 28, 2025

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it is a move, but just these short_channel_id's made unique to make it easier to test things for attr errors
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 2,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 3,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 4,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ],
 blinded_tail: None,
 }
	}

	fn build_test_onion_keys() -> Vec<OnionKeys> {
 // Keys from BOLT 4, used in both test vector tests
 let secp_ctx = Secp256k1::new();

 let route = Route {
 paths: vec![Path { hops: vec![
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ], blinded_tail: None }],
 route_params: None,
 };
 let path = build_test_path();
 let route = Route { paths: vec![path], route_params: None };

 let onion_keys =
 super::construct_onion_keys(&secp_ctx, &route.paths[0], &get_test_session_key())
Expand DownExpand Up@@ -2078,6 +2163,108 @@ mod tests {
 );
 let hex = "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";
 assert_eq!(onion_packet_5.data, <Vec<u8>>::from_hex(hex).unwrap());

 let logger: Arc<TestLogger> = Arc::new(TestLogger::new());
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 // Assert that the original failure can be retrieved and that all hmacs check out.
 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, onion_packet_5.data);

 assert_eq!(decrypted_failure.onion_error_code, Some(0x2002));
	}

	#[test]
	fn test_non_attributable_failure_packet_onion() {
 // Create a failure packet with bogus data.
 let packet = vec![1u8; 292];

 // In the current protocol, it is unfortunately not possible to identify the failure source.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet);
 assert_eq!(decrypted_failure.short_channel_id, None);

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Non-attributable failure encountered",
 1,
 );
	}

	#[test]
	fn test_unreadable_failure_packet_onion() {
 // Create a failure packet with a valid hmac but unreadable failure message.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 // The failure message is a single 0 byte.
 let mut packet = [0u8; 33];

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet[32..]);
 let hmac = Hmac::from_engine(hmac).to_byte_array();
 packet[..32].copy_from_slice(&hmac);

 let packet = encrypt_failure_packet(shared_secret, &packet);

 // For the unreadable failure, it is still expected that the failing channel can be identified.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains("lightning::ln::onion_utils", "Unreadable failure", 1);
	}

	#[test]
	fn test_missing_error_code() {
 // Create a failure packet with a valid hmac and structure, but no error code.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 let failuremsg = vec![1];
 let pad = Vec::new();
 let mut packet = msgs::DecodedOnionErrorPacket { hmac: [0; 32], failuremsg, pad };

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet.encode()[32..]);
 packet.hmac = Hmac::from_engine(hmac).to_byte_array();

 let packet = encrypt_failure_packet(shared_secret, &packet.encode()[..]);

 let logger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Missing error code in failure",
 1,
 );
	}

	fn test_failure_attribution(logger: &TestLogger, packet: &[u8]) -> DecodedOnionFailure {
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, packet.into());

 decrypted_failure
	}

	struct RawOnionHopData {
Expand Down

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var ref = document.referrer;
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}
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try {
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var __re = new RegExp('^' + ".*" + '
Log cases where an onion failure cannot be attributed or interpreted by joostjager · Pull Request #3629 · lightningdevkit/rust-lightning · GitHub
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 Merged

arik-so
merged 4 commits into

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Mar 4, 2025
 Merged


Log cases where an onion failure cannot be attributed or interpreted
#3629
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447148d

Add test coverage for process_onion_failure


joostjager Feb 28, 2025
f307ab7

Remove error side effect from decrypt_onion_error_packet


joostjager Mar 3, 2025
00f42de

Log cases where an onion failure cannot be attributed or interpreted


joostjager Feb 28, 2025
f38244c

Properly attribute unreadable failures with a valid hmac


joostjager Feb 28, 2025

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277 changes: 232 additions & 45 deletions
lightning/src/ln/onion_utils.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -931,15 +931,11 @@ pub(crate) struct DecodedOnionFailure {
	pub(crate) onion_error_data: Option<Vec<u8>>,
}

/// Note that we always decrypt `packet` in-place here even if the deserialization into
/// [`msgs::DecodedOnionErrorPacket`] ultimately fails.
fn decrypt_onion_error_packet(
	packet: &mut Vec<u8>, shared_secret: SharedSecret,
) -> Result<msgs::DecodedOnionErrorPacket, msgs::DecodeError> {
/// Decrypt the error packet in-place.
fn decrypt_onion_error_packet(packet: &mut Vec<u8>, shared_secret: SharedSecret) {
@arik-soarik-soMar 4, 2025

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I almost wonder whether it's one of those instances where in-place processing is what largely contributes to confusion. Getting a result back with the decrypted packet or with the decryption error, without worrying about the input argument getting changed, seems preferable.
@joostjagerjoostjagerMar 4, 2025

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The confusion was mainly that this used to be a function that returned a value and still had a side effect too. A side effect that was also needed, because the decrypted packet needs to be processed for the next hop.
Could have returned a decrypted copy in addition to the decoded failure to make it a pure function, probably with some performance implications. But I think now that this function has no return value anymore and only decrypts in-place, it's already a lot better.
	let ammag = gen_ammag_from_shared_secret(shared_secret.as_ref());
	let mut chacha = ChaCha20::new(&ammag, &[0u8; 8]);
	chacha.process_in_place(packet);
	msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(packet))
}

/// Process failure we got back from upstream on a payment we sent (implying htlc_source is an
Expand DownExpand Up@@ -1021,9 +1017,11 @@ where
 {
 // Actually parse the onion error data in tests so we can check that blinded hops fail
 // back correctly.
 let err_packet =
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret)
 .unwrap();
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);
 let err_packet = msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(
 &encrypted_packet,
 ))
 .unwrap();
 error_code_ret = Some(u16::from_be_bytes(
 err_packet.failuremsg.get(0..2).unwrap().try_into().unwrap(),
 ));
Expand All@@ -1044,22 +1042,44 @@ where
 let amt_to_forward = htlc_msat - route_hop.fee_msat;
 htlc_msat = amt_to_forward;

 let err_packet = match decrypt_onion_error_packet(&mut encrypted_packet, shared_secret) {
 Ok(p) => p,
 Err(_) => return,
 };
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);

 let um = gen_um_from_shared_secret(shared_secret.as_ref());
 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&err_packet.encode()[32..]);
 hmac.input(&encrypted_packet[32..]);

 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &err_packet.hmac) {
 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &encrypted_packet[..32]) {
 return;
 }

 let err_packet =
 match msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(&encrypted_packet)) {
 Ok(p) => p,
 Err(_) => {
 log_warn!(logger, "Unreadable failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
 });
 let short_channel_id = Some(route_hop.short_channel_id);
 res = Some(FailureLearnings {
 network_update,
 short_channel_id,
 payment_failed_permanently: is_from_final_node,
 failed_within_blinded_path: false,
 });
 return;
 },
 };

 let error_code_slice = match err_packet.failuremsg.get(0..2) {
 Some(s) => s,
 None => {
 // Useless packet that we can't use but it passed HMAC, so it definitely came from the peer
 // in question
 log_warn!(logger, "Missing error code in failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
Expand DownExpand Up@@ -1219,6 +1239,12 @@ where
	} else {
 // only not set either packet unparseable or hmac does not match with any
 // payment not retryable only when garbage is from the final node
 log_warn!(
 logger,
 "Non-attributable failure encountered on route {}",
 path.hops.iter().map(|h| h.pubkey.to_string()).collect::<Vec<_>>().join("->")
 );

 DecodedOnionFailure {
 network_update: None,
 short_channel_id: None,
Expand DownExpand Up@@ -1764,7 +1790,10 @@ fn decode_next_hop<T, R: ReadableArgs<T>, N: NextPacketBytes>(

#[cfg(test)]
mod tests {
	use std::sync::Arc;

	use crate::io;
	use crate::ln::channelmanager::PaymentId;
	use crate::ln::msgs;
	use crate::routing::router::{Path, PaymentParameters, Route, RouteHop};
	use crate::types::features::{ChannelFeatures, NodeFeatures};
Expand All@@ -1773,6 +1802,7 @@ mod tests {

	#[allow(unused_imports)]
	use crate::prelude::*;
	use crate::util::test_utils::TestLogger;

	use bitcoin::hex::FromHex;
	use bitcoin::secp256k1::Secp256k1;
Expand All@@ -1785,40 +1815,95 @@ mod tests {
 SecretKey::from_slice(&<Vec<u8>>::from_hex(hex).unwrap()[..]).unwrap()
	}

	fn build_test_path() -> Path {
 Path {
 hops: vec![
 RouteHop {
@joostjagerjoostjagerFeb 28, 2025

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rustfmt wanted this
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 0,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 1,
@joostjagerjoostjagerFeb 28, 2025

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it is a move, but just these short_channel_id's made unique to make it easier to test things for attr errors
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 2,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 3,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 4,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ],
 blinded_tail: None,
 }
	}

	fn build_test_onion_keys() -> Vec<OnionKeys> {
 // Keys from BOLT 4, used in both test vector tests
 let secp_ctx = Secp256k1::new();

 let route = Route {
 paths: vec![Path { hops: vec![
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ], blinded_tail: None }],
 route_params: None,
 };
 let path = build_test_path();
 let route = Route { paths: vec![path], route_params: None };

 let onion_keys =
 super::construct_onion_keys(&secp_ctx, &route.paths[0], &get_test_session_key())
Expand DownExpand Up@@ -2078,6 +2163,108 @@ mod tests {
 );
 let hex = "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";
 assert_eq!(onion_packet_5.data, <Vec<u8>>::from_hex(hex).unwrap());

 let logger: Arc<TestLogger> = Arc::new(TestLogger::new());
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 // Assert that the original failure can be retrieved and that all hmacs check out.
 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, onion_packet_5.data);

 assert_eq!(decrypted_failure.onion_error_code, Some(0x2002));
	}

	#[test]
	fn test_non_attributable_failure_packet_onion() {
 // Create a failure packet with bogus data.
 let packet = vec![1u8; 292];

 // In the current protocol, it is unfortunately not possible to identify the failure source.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet);
 assert_eq!(decrypted_failure.short_channel_id, None);

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Non-attributable failure encountered",
 1,
 );
	}

	#[test]
	fn test_unreadable_failure_packet_onion() {
 // Create a failure packet with a valid hmac but unreadable failure message.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 // The failure message is a single 0 byte.
 let mut packet = [0u8; 33];

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet[32..]);
 let hmac = Hmac::from_engine(hmac).to_byte_array();
 packet[..32].copy_from_slice(&hmac);

 let packet = encrypt_failure_packet(shared_secret, &packet);

 // For the unreadable failure, it is still expected that the failing channel can be identified.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains("lightning::ln::onion_utils", "Unreadable failure", 1);
	}

	#[test]
	fn test_missing_error_code() {
 // Create a failure packet with a valid hmac and structure, but no error code.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 let failuremsg = vec![1];
 let pad = Vec::new();
 let mut packet = msgs::DecodedOnionErrorPacket { hmac: [0; 32], failuremsg, pad };

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet.encode()[32..]);
 packet.hmac = Hmac::from_engine(hmac).to_byte_array();

 let packet = encrypt_failure_packet(shared_secret, &packet.encode()[..]);

 let logger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Missing error code in failure",
 1,
 );
	}

	fn test_failure_attribution(logger: &TestLogger, packet: &[u8]) -> DecodedOnionFailure {
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, packet.into());

 decrypted_failure
	}

	struct RawOnionHopData {
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
Log cases where an onion failure cannot be attributed or interpreted by joostjager · Pull Request #3629 · lightningdevkit/rust-lightning · GitHub
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arik-so
merged 4 commits into

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Mar 4, 2025
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Log cases where an onion failure cannot be attributed or interpreted
#3629
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447148d

Add test coverage for process_onion_failure


joostjager Feb 28, 2025
f307ab7

Remove error side effect from decrypt_onion_error_packet


joostjager Mar 3, 2025
00f42de

Log cases where an onion failure cannot be attributed or interpreted


joostjager Feb 28, 2025
f38244c

Properly attribute unreadable failures with a valid hmac


joostjager Feb 28, 2025

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277 changes: 232 additions & 45 deletions
lightning/src/ln/onion_utils.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -931,15 +931,11 @@ pub(crate) struct DecodedOnionFailure {
	pub(crate) onion_error_data: Option<Vec<u8>>,
}

/// Note that we always decrypt `packet` in-place here even if the deserialization into
/// [`msgs::DecodedOnionErrorPacket`] ultimately fails.
fn decrypt_onion_error_packet(
	packet: &mut Vec<u8>, shared_secret: SharedSecret,
) -> Result<msgs::DecodedOnionErrorPacket, msgs::DecodeError> {
/// Decrypt the error packet in-place.
fn decrypt_onion_error_packet(packet: &mut Vec<u8>, shared_secret: SharedSecret) {
@arik-soarik-soMar 4, 2025

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I almost wonder whether it's one of those instances where in-place processing is what largely contributes to confusion. Getting a result back with the decrypted packet or with the decryption error, without worrying about the input argument getting changed, seems preferable.
@joostjagerjoostjagerMar 4, 2025

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The confusion was mainly that this used to be a function that returned a value and still had a side effect too. A side effect that was also needed, because the decrypted packet needs to be processed for the next hop.
Could have returned a decrypted copy in addition to the decoded failure to make it a pure function, probably with some performance implications. But I think now that this function has no return value anymore and only decrypts in-place, it's already a lot better.
	let ammag = gen_ammag_from_shared_secret(shared_secret.as_ref());
	let mut chacha = ChaCha20::new(&ammag, &[0u8; 8]);
	chacha.process_in_place(packet);
	msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(packet))
}

/// Process failure we got back from upstream on a payment we sent (implying htlc_source is an
Expand DownExpand Up@@ -1021,9 +1017,11 @@ where
 {
 // Actually parse the onion error data in tests so we can check that blinded hops fail
 // back correctly.
 let err_packet =
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret)
 .unwrap();
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);
 let err_packet = msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(
 &encrypted_packet,
 ))
 .unwrap();
 error_code_ret = Some(u16::from_be_bytes(
 err_packet.failuremsg.get(0..2).unwrap().try_into().unwrap(),
 ));
Expand All@@ -1044,22 +1042,44 @@ where
 let amt_to_forward = htlc_msat - route_hop.fee_msat;
 htlc_msat = amt_to_forward;

 let err_packet = match decrypt_onion_error_packet(&mut encrypted_packet, shared_secret) {
 Ok(p) => p,
 Err(_) => return,
 };
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);

 let um = gen_um_from_shared_secret(shared_secret.as_ref());
 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&err_packet.encode()[32..]);
 hmac.input(&encrypted_packet[32..]);

 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &err_packet.hmac) {
 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &encrypted_packet[..32]) {
 return;
 }

 let err_packet =
 match msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(&encrypted_packet)) {
 Ok(p) => p,
 Err(_) => {
 log_warn!(logger, "Unreadable failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
 });
 let short_channel_id = Some(route_hop.short_channel_id);
 res = Some(FailureLearnings {
 network_update,
 short_channel_id,
 payment_failed_permanently: is_from_final_node,
 failed_within_blinded_path: false,
 });
 return;
 },
 };

 let error_code_slice = match err_packet.failuremsg.get(0..2) {
 Some(s) => s,
 None => {
 // Useless packet that we can't use but it passed HMAC, so it definitely came from the peer
 // in question
 log_warn!(logger, "Missing error code in failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
Expand DownExpand Up@@ -1219,6 +1239,12 @@ where
	} else {
 // only not set either packet unparseable or hmac does not match with any
 // payment not retryable only when garbage is from the final node
 log_warn!(
 logger,
 "Non-attributable failure encountered on route {}",
 path.hops.iter().map(|h| h.pubkey.to_string()).collect::<Vec<_>>().join("->")
 );

 DecodedOnionFailure {
 network_update: None,
 short_channel_id: None,
Expand DownExpand Up@@ -1764,7 +1790,10 @@ fn decode_next_hop<T, R: ReadableArgs<T>, N: NextPacketBytes>(

#[cfg(test)]
mod tests {
	use std::sync::Arc;

	use crate::io;
	use crate::ln::channelmanager::PaymentId;
	use crate::ln::msgs;
	use crate::routing::router::{Path, PaymentParameters, Route, RouteHop};
	use crate::types::features::{ChannelFeatures, NodeFeatures};
Expand All@@ -1773,6 +1802,7 @@ mod tests {

	#[allow(unused_imports)]
	use crate::prelude::*;
	use crate::util::test_utils::TestLogger;

	use bitcoin::hex::FromHex;
	use bitcoin::secp256k1::Secp256k1;
Expand All@@ -1785,40 +1815,95 @@ mod tests {
 SecretKey::from_slice(&<Vec<u8>>::from_hex(hex).unwrap()[..]).unwrap()
	}

	fn build_test_path() -> Path {
 Path {
 hops: vec![
 RouteHop {
@joostjagerjoostjagerFeb 28, 2025

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rustfmt wanted this
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 0,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 1,
@joostjagerjoostjagerFeb 28, 2025

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it is a move, but just these short_channel_id's made unique to make it easier to test things for attr errors
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 2,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 3,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 4,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ],
 blinded_tail: None,
 }
	}

	fn build_test_onion_keys() -> Vec<OnionKeys> {
 // Keys from BOLT 4, used in both test vector tests
 let secp_ctx = Secp256k1::new();

 let route = Route {
 paths: vec![Path { hops: vec![
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ], blinded_tail: None }],
 route_params: None,
 };
 let path = build_test_path();
 let route = Route { paths: vec![path], route_params: None };

 let onion_keys =
 super::construct_onion_keys(&secp_ctx, &route.paths[0], &get_test_session_key())
Expand DownExpand Up@@ -2078,6 +2163,108 @@ mod tests {
 );
 let hex = "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";
 assert_eq!(onion_packet_5.data, <Vec<u8>>::from_hex(hex).unwrap());

 let logger: Arc<TestLogger> = Arc::new(TestLogger::new());
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 // Assert that the original failure can be retrieved and that all hmacs check out.
 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, onion_packet_5.data);

 assert_eq!(decrypted_failure.onion_error_code, Some(0x2002));
	}

	#[test]
	fn test_non_attributable_failure_packet_onion() {
 // Create a failure packet with bogus data.
 let packet = vec![1u8; 292];

 // In the current protocol, it is unfortunately not possible to identify the failure source.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet);
 assert_eq!(decrypted_failure.short_channel_id, None);

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Non-attributable failure encountered",
 1,
 );
	}

	#[test]
	fn test_unreadable_failure_packet_onion() {
 // Create a failure packet with a valid hmac but unreadable failure message.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 // The failure message is a single 0 byte.
 let mut packet = [0u8; 33];

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet[32..]);
 let hmac = Hmac::from_engine(hmac).to_byte_array();
 packet[..32].copy_from_slice(&hmac);

 let packet = encrypt_failure_packet(shared_secret, &packet);

 // For the unreadable failure, it is still expected that the failing channel can be identified.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains("lightning::ln::onion_utils", "Unreadable failure", 1);
	}

	#[test]
	fn test_missing_error_code() {
 // Create a failure packet with a valid hmac and structure, but no error code.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 let failuremsg = vec![1];
 let pad = Vec::new();
 let mut packet = msgs::DecodedOnionErrorPacket { hmac: [0; 32], failuremsg, pad };

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet.encode()[32..]);
 packet.hmac = Hmac::from_engine(hmac).to_byte_array();

 let packet = encrypt_failure_packet(shared_secret, &packet.encode()[..]);

 let logger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Missing error code in failure",
 1,
 );
	}

	fn test_failure_attribution(logger: &TestLogger, packet: &[u8]) -> DecodedOnionFailure {
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, packet.into());

 decrypted_failure
	}

	struct RawOnionHopData {
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Log cases where an onion failure cannot be attributed or interpreted by joostjager · Pull Request #3629 · lightningdevkit/rust-lightning · GitHub
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 Merged

arik-so
merged 4 commits into

from

Mar 4, 2025
 Merged


Log cases where an onion failure cannot be attributed or interpreted
#3629
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4 commits


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Hold shift + click to select a range
447148d

Add test coverage for process_onion_failure


joostjager Feb 28, 2025
f307ab7

Remove error side effect from decrypt_onion_error_packet


joostjager Mar 3, 2025
00f42de

Log cases where an onion failure cannot be attributed or interpreted


joostjager Feb 28, 2025
f38244c

Properly attribute unreadable failures with a valid hmac


joostjager Feb 28, 2025

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277 changes: 232 additions & 45 deletions
lightning/src/ln/onion_utils.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -931,15 +931,11 @@ pub(crate) struct DecodedOnionFailure {
	pub(crate) onion_error_data: Option<Vec<u8>>,
}

/// Note that we always decrypt `packet` in-place here even if the deserialization into
/// [`msgs::DecodedOnionErrorPacket`] ultimately fails.
fn decrypt_onion_error_packet(
	packet: &mut Vec<u8>, shared_secret: SharedSecret,
) -> Result<msgs::DecodedOnionErrorPacket, msgs::DecodeError> {
/// Decrypt the error packet in-place.
fn decrypt_onion_error_packet(packet: &mut Vec<u8>, shared_secret: SharedSecret) {
@arik-soarik-soMar 4, 2025

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I almost wonder whether it's one of those instances where in-place processing is what largely contributes to confusion. Getting a result back with the decrypted packet or with the decryption error, without worrying about the input argument getting changed, seems preferable.
@joostjagerjoostjagerMar 4, 2025

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The confusion was mainly that this used to be a function that returned a value and still had a side effect too. A side effect that was also needed, because the decrypted packet needs to be processed for the next hop.
Could have returned a decrypted copy in addition to the decoded failure to make it a pure function, probably with some performance implications. But I think now that this function has no return value anymore and only decrypts in-place, it's already a lot better.
	let ammag = gen_ammag_from_shared_secret(shared_secret.as_ref());
	let mut chacha = ChaCha20::new(&ammag, &[0u8; 8]);
	chacha.process_in_place(packet);
	msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(packet))
}

/// Process failure we got back from upstream on a payment we sent (implying htlc_source is an
Expand DownExpand Up@@ -1021,9 +1017,11 @@ where
 {
 // Actually parse the onion error data in tests so we can check that blinded hops fail
 // back correctly.
 let err_packet =
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret)
 .unwrap();
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);
 let err_packet = msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(
 &encrypted_packet,
 ))
 .unwrap();
 error_code_ret = Some(u16::from_be_bytes(
 err_packet.failuremsg.get(0..2).unwrap().try_into().unwrap(),
 ));
Expand All@@ -1044,22 +1042,44 @@ where
 let amt_to_forward = htlc_msat - route_hop.fee_msat;
 htlc_msat = amt_to_forward;

 let err_packet = match decrypt_onion_error_packet(&mut encrypted_packet, shared_secret) {
 Ok(p) => p,
 Err(_) => return,
 };
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);

 let um = gen_um_from_shared_secret(shared_secret.as_ref());
 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&err_packet.encode()[32..]);
 hmac.input(&encrypted_packet[32..]);

 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &err_packet.hmac) {
 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &encrypted_packet[..32]) {
 return;
 }

 let err_packet =
 match msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(&encrypted_packet)) {
 Ok(p) => p,
 Err(_) => {
 log_warn!(logger, "Unreadable failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
 });
 let short_channel_id = Some(route_hop.short_channel_id);
 res = Some(FailureLearnings {
 network_update,
 short_channel_id,
 payment_failed_permanently: is_from_final_node,
 failed_within_blinded_path: false,
 });
 return;
 },
 };

 let error_code_slice = match err_packet.failuremsg.get(0..2) {
 Some(s) => s,
 None => {
 // Useless packet that we can't use but it passed HMAC, so it definitely came from the peer
 // in question
 log_warn!(logger, "Missing error code in failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
Expand DownExpand Up@@ -1219,6 +1239,12 @@ where
	} else {
 // only not set either packet unparseable or hmac does not match with any
 // payment not retryable only when garbage is from the final node
 log_warn!(
 logger,
 "Non-attributable failure encountered on route {}",
 path.hops.iter().map(|h| h.pubkey.to_string()).collect::<Vec<_>>().join("->")
 );

 DecodedOnionFailure {
 network_update: None,
 short_channel_id: None,
Expand DownExpand Up@@ -1764,7 +1790,10 @@ fn decode_next_hop<T, R: ReadableArgs<T>, N: NextPacketBytes>(

#[cfg(test)]
mod tests {
	use std::sync::Arc;

	use crate::io;
	use crate::ln::channelmanager::PaymentId;
	use crate::ln::msgs;
	use crate::routing::router::{Path, PaymentParameters, Route, RouteHop};
	use crate::types::features::{ChannelFeatures, NodeFeatures};
Expand All@@ -1773,6 +1802,7 @@ mod tests {

	#[allow(unused_imports)]
	use crate::prelude::*;
	use crate::util::test_utils::TestLogger;

	use bitcoin::hex::FromHex;
	use bitcoin::secp256k1::Secp256k1;
Expand All@@ -1785,40 +1815,95 @@ mod tests {
 SecretKey::from_slice(&<Vec<u8>>::from_hex(hex).unwrap()[..]).unwrap()
	}

	fn build_test_path() -> Path {
 Path {
 hops: vec![
 RouteHop {
@joostjagerjoostjagerFeb 28, 2025

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rustfmt wanted this
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 0,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 1,
@joostjagerjoostjagerFeb 28, 2025

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it is a move, but just these short_channel_id's made unique to make it easier to test things for attr errors
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 2,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 3,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 4,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ],
 blinded_tail: None,
 }
	}

	fn build_test_onion_keys() -> Vec<OnionKeys> {
 // Keys from BOLT 4, used in both test vector tests
 let secp_ctx = Secp256k1::new();

 let route = Route {
 paths: vec![Path { hops: vec![
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ], blinded_tail: None }],
 route_params: None,
 };
 let path = build_test_path();
 let route = Route { paths: vec![path], route_params: None };

 let onion_keys =
 super::construct_onion_keys(&secp_ctx, &route.paths[0], &get_test_session_key())
Expand DownExpand Up@@ -2078,6 +2163,108 @@ mod tests {
 );
 let hex = "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";
 assert_eq!(onion_packet_5.data, <Vec<u8>>::from_hex(hex).unwrap());

 let logger: Arc<TestLogger> = Arc::new(TestLogger::new());
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 // Assert that the original failure can be retrieved and that all hmacs check out.
 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, onion_packet_5.data);

 assert_eq!(decrypted_failure.onion_error_code, Some(0x2002));
	}

	#[test]
	fn test_non_attributable_failure_packet_onion() {
 // Create a failure packet with bogus data.
 let packet = vec![1u8; 292];

 // In the current protocol, it is unfortunately not possible to identify the failure source.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet);
 assert_eq!(decrypted_failure.short_channel_id, None);

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Non-attributable failure encountered",
 1,
 );
	}

	#[test]
	fn test_unreadable_failure_packet_onion() {
 // Create a failure packet with a valid hmac but unreadable failure message.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 // The failure message is a single 0 byte.
 let mut packet = [0u8; 33];

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet[32..]);
 let hmac = Hmac::from_engine(hmac).to_byte_array();
 packet[..32].copy_from_slice(&hmac);

 let packet = encrypt_failure_packet(shared_secret, &packet);

 // For the unreadable failure, it is still expected that the failing channel can be identified.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains("lightning::ln::onion_utils", "Unreadable failure", 1);
	}

	#[test]
	fn test_missing_error_code() {
 // Create a failure packet with a valid hmac and structure, but no error code.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 let failuremsg = vec![1];
 let pad = Vec::new();
 let mut packet = msgs::DecodedOnionErrorPacket { hmac: [0; 32], failuremsg, pad };

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet.encode()[32..]);
 packet.hmac = Hmac::from_engine(hmac).to_byte_array();

 let packet = encrypt_failure_packet(shared_secret, &packet.encode()[..]);

 let logger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Missing error code in failure",
 1,
 );
	}

	fn test_failure_attribution(logger: &TestLogger, packet: &[u8]) -> DecodedOnionFailure {
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, packet.into());

 decrypted_failure
	}

	struct RawOnionHopData {
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Log cases where an onion failure cannot be attributed or interpreted by joostjager · Pull Request #3629 · lightningdevkit/rust-lightning · GitHub
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 Merged

arik-so
merged 4 commits into

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Mar 4, 2025
 Merged


Log cases where an onion failure cannot be attributed or interpreted
#3629
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447148d

Add test coverage for process_onion_failure


joostjager Feb 28, 2025
f307ab7

Remove error side effect from decrypt_onion_error_packet


joostjager Mar 3, 2025
00f42de

Log cases where an onion failure cannot be attributed or interpreted


joostjager Feb 28, 2025
f38244c

Properly attribute unreadable failures with a valid hmac


joostjager Feb 28, 2025

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277 changes: 232 additions & 45 deletions
lightning/src/ln/onion_utils.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -931,15 +931,11 @@ pub(crate) struct DecodedOnionFailure {
	pub(crate) onion_error_data: Option<Vec<u8>>,
}

/// Note that we always decrypt `packet` in-place here even if the deserialization into
/// [`msgs::DecodedOnionErrorPacket`] ultimately fails.
fn decrypt_onion_error_packet(
	packet: &mut Vec<u8>, shared_secret: SharedSecret,
) -> Result<msgs::DecodedOnionErrorPacket, msgs::DecodeError> {
/// Decrypt the error packet in-place.
fn decrypt_onion_error_packet(packet: &mut Vec<u8>, shared_secret: SharedSecret) {
@arik-soarik-soMar 4, 2025

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I almost wonder whether it's one of those instances where in-place processing is what largely contributes to confusion. Getting a result back with the decrypted packet or with the decryption error, without worrying about the input argument getting changed, seems preferable.
@joostjagerjoostjagerMar 4, 2025

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The confusion was mainly that this used to be a function that returned a value and still had a side effect too. A side effect that was also needed, because the decrypted packet needs to be processed for the next hop.
Could have returned a decrypted copy in addition to the decoded failure to make it a pure function, probably with some performance implications. But I think now that this function has no return value anymore and only decrypts in-place, it's already a lot better.
	let ammag = gen_ammag_from_shared_secret(shared_secret.as_ref());
	let mut chacha = ChaCha20::new(&ammag, &[0u8; 8]);
	chacha.process_in_place(packet);
	msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(packet))
}

/// Process failure we got back from upstream on a payment we sent (implying htlc_source is an
Expand DownExpand Up@@ -1021,9 +1017,11 @@ where
 {
 // Actually parse the onion error data in tests so we can check that blinded hops fail
 // back correctly.
 let err_packet =
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret)
 .unwrap();
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);
 let err_packet = msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(
 &encrypted_packet,
 ))
 .unwrap();
 error_code_ret = Some(u16::from_be_bytes(
 err_packet.failuremsg.get(0..2).unwrap().try_into().unwrap(),
 ));
Expand All@@ -1044,22 +1042,44 @@ where
 let amt_to_forward = htlc_msat - route_hop.fee_msat;
 htlc_msat = amt_to_forward;

 let err_packet = match decrypt_onion_error_packet(&mut encrypted_packet, shared_secret) {
 Ok(p) => p,
 Err(_) => return,
 };
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);

 let um = gen_um_from_shared_secret(shared_secret.as_ref());
 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&err_packet.encode()[32..]);
 hmac.input(&encrypted_packet[32..]);

 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &err_packet.hmac) {
 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &encrypted_packet[..32]) {
 return;
 }

 let err_packet =
 match msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(&encrypted_packet)) {
 Ok(p) => p,
 Err(_) => {
 log_warn!(logger, "Unreadable failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
 });
 let short_channel_id = Some(route_hop.short_channel_id);
 res = Some(FailureLearnings {
 network_update,
 short_channel_id,
 payment_failed_permanently: is_from_final_node,
 failed_within_blinded_path: false,
 });
 return;
 },
 };

 let error_code_slice = match err_packet.failuremsg.get(0..2) {
 Some(s) => s,
 None => {
 // Useless packet that we can't use but it passed HMAC, so it definitely came from the peer
 // in question
 log_warn!(logger, "Missing error code in failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
Expand DownExpand Up@@ -1219,6 +1239,12 @@ where
	} else {
 // only not set either packet unparseable or hmac does not match with any
 // payment not retryable only when garbage is from the final node
 log_warn!(
 logger,
 "Non-attributable failure encountered on route {}",
 path.hops.iter().map(|h| h.pubkey.to_string()).collect::<Vec<_>>().join("->")
 );

 DecodedOnionFailure {
 network_update: None,
 short_channel_id: None,
Expand DownExpand Up@@ -1764,7 +1790,10 @@ fn decode_next_hop<T, R: ReadableArgs<T>, N: NextPacketBytes>(

#[cfg(test)]
mod tests {
	use std::sync::Arc;

	use crate::io;
	use crate::ln::channelmanager::PaymentId;
	use crate::ln::msgs;
	use crate::routing::router::{Path, PaymentParameters, Route, RouteHop};
	use crate::types::features::{ChannelFeatures, NodeFeatures};
Expand All@@ -1773,6 +1802,7 @@ mod tests {

	#[allow(unused_imports)]
	use crate::prelude::*;
	use crate::util::test_utils::TestLogger;

	use bitcoin::hex::FromHex;
	use bitcoin::secp256k1::Secp256k1;
Expand All@@ -1785,40 +1815,95 @@ mod tests {
 SecretKey::from_slice(&<Vec<u8>>::from_hex(hex).unwrap()[..]).unwrap()
	}

	fn build_test_path() -> Path {
 Path {
 hops: vec![
 RouteHop {
@joostjagerjoostjagerFeb 28, 2025

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rustfmt wanted this
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 0,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 1,
@joostjagerjoostjagerFeb 28, 2025

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it is a move, but just these short_channel_id's made unique to make it easier to test things for attr errors
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 2,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 3,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 4,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ],
 blinded_tail: None,
 }
	}

	fn build_test_onion_keys() -> Vec<OnionKeys> {
 // Keys from BOLT 4, used in both test vector tests
 let secp_ctx = Secp256k1::new();

 let route = Route {
 paths: vec![Path { hops: vec![
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ], blinded_tail: None }],
 route_params: None,
 };
 let path = build_test_path();
 let route = Route { paths: vec![path], route_params: None };

 let onion_keys =
 super::construct_onion_keys(&secp_ctx, &route.paths[0], &get_test_session_key())
Expand DownExpand Up@@ -2078,6 +2163,108 @@ mod tests {
 );
 let hex = "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";
 assert_eq!(onion_packet_5.data, <Vec<u8>>::from_hex(hex).unwrap());

 let logger: Arc<TestLogger> = Arc::new(TestLogger::new());
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 // Assert that the original failure can be retrieved and that all hmacs check out.
 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, onion_packet_5.data);

 assert_eq!(decrypted_failure.onion_error_code, Some(0x2002));
	}

	#[test]
	fn test_non_attributable_failure_packet_onion() {
 // Create a failure packet with bogus data.
 let packet = vec![1u8; 292];

 // In the current protocol, it is unfortunately not possible to identify the failure source.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet);
 assert_eq!(decrypted_failure.short_channel_id, None);

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Non-attributable failure encountered",
 1,
 );
	}

	#[test]
	fn test_unreadable_failure_packet_onion() {
 // Create a failure packet with a valid hmac but unreadable failure message.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 // The failure message is a single 0 byte.
 let mut packet = [0u8; 33];

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet[32..]);
 let hmac = Hmac::from_engine(hmac).to_byte_array();
 packet[..32].copy_from_slice(&hmac);

 let packet = encrypt_failure_packet(shared_secret, &packet);

 // For the unreadable failure, it is still expected that the failing channel can be identified.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains("lightning::ln::onion_utils", "Unreadable failure", 1);
	}

	#[test]
	fn test_missing_error_code() {
 // Create a failure packet with a valid hmac and structure, but no error code.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 let failuremsg = vec![1];
 let pad = Vec::new();
 let mut packet = msgs::DecodedOnionErrorPacket { hmac: [0; 32], failuremsg, pad };

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet.encode()[32..]);
 packet.hmac = Hmac::from_engine(hmac).to_byte_array();

 let packet = encrypt_failure_packet(shared_secret, &packet.encode()[..]);

 let logger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Missing error code in failure",
 1,
 );
	}

	fn test_failure_attribution(logger: &TestLogger, packet: &[u8]) -> DecodedOnionFailure {
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, packet.into());

 decrypted_failure
	}

	struct RawOnionHopData {
Expand Down

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
Log cases where an onion failure cannot be attributed or interpreted by joostjager · Pull Request #3629 · lightningdevkit/rust-lightning · GitHub
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 Merged

arik-so
merged 4 commits into

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Mar 4, 2025
 Merged


Log cases where an onion failure cannot be attributed or interpreted
#3629
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447148d

Add test coverage for process_onion_failure


joostjager Feb 28, 2025
f307ab7

Remove error side effect from decrypt_onion_error_packet


joostjager Mar 3, 2025
00f42de

Log cases where an onion failure cannot be attributed or interpreted


joostjager Feb 28, 2025
f38244c

Properly attribute unreadable failures with a valid hmac


joostjager Feb 28, 2025

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277 changes: 232 additions & 45 deletions
lightning/src/ln/onion_utils.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -931,15 +931,11 @@ pub(crate) struct DecodedOnionFailure {
	pub(crate) onion_error_data: Option<Vec<u8>>,
}

/// Note that we always decrypt `packet` in-place here even if the deserialization into
/// [`msgs::DecodedOnionErrorPacket`] ultimately fails.
fn decrypt_onion_error_packet(
	packet: &mut Vec<u8>, shared_secret: SharedSecret,
) -> Result<msgs::DecodedOnionErrorPacket, msgs::DecodeError> {
/// Decrypt the error packet in-place.
fn decrypt_onion_error_packet(packet: &mut Vec<u8>, shared_secret: SharedSecret) {
@arik-soarik-soMar 4, 2025

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I almost wonder whether it's one of those instances where in-place processing is what largely contributes to confusion. Getting a result back with the decrypted packet or with the decryption error, without worrying about the input argument getting changed, seems preferable.
@joostjagerjoostjagerMar 4, 2025

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The confusion was mainly that this used to be a function that returned a value and still had a side effect too. A side effect that was also needed, because the decrypted packet needs to be processed for the next hop.
Could have returned a decrypted copy in addition to the decoded failure to make it a pure function, probably with some performance implications. But I think now that this function has no return value anymore and only decrypts in-place, it's already a lot better.
	let ammag = gen_ammag_from_shared_secret(shared_secret.as_ref());
	let mut chacha = ChaCha20::new(&ammag, &[0u8; 8]);
	chacha.process_in_place(packet);
	msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(packet))
}

/// Process failure we got back from upstream on a payment we sent (implying htlc_source is an
Expand DownExpand Up@@ -1021,9 +1017,11 @@ where
 {
 // Actually parse the onion error data in tests so we can check that blinded hops fail
 // back correctly.
 let err_packet =
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret)
 .unwrap();
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);
 let err_packet = msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(
 &encrypted_packet,
 ))
 .unwrap();
 error_code_ret = Some(u16::from_be_bytes(
 err_packet.failuremsg.get(0..2).unwrap().try_into().unwrap(),
 ));
Expand All@@ -1044,22 +1042,44 @@ where
 let amt_to_forward = htlc_msat - route_hop.fee_msat;
 htlc_msat = amt_to_forward;

 let err_packet = match decrypt_onion_error_packet(&mut encrypted_packet, shared_secret) {
 Ok(p) => p,
 Err(_) => return,
 };
 decrypt_onion_error_packet(&mut encrypted_packet, shared_secret);

 let um = gen_um_from_shared_secret(shared_secret.as_ref());
 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&err_packet.encode()[32..]);
 hmac.input(&encrypted_packet[32..]);

 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &err_packet.hmac) {
 if !fixed_time_eq(&Hmac::from_engine(hmac).to_byte_array(), &encrypted_packet[..32]) {
 return;
 }

 let err_packet =
 match msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(&encrypted_packet)) {
 Ok(p) => p,
 Err(_) => {
 log_warn!(logger, "Unreadable failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
 });
 let short_channel_id = Some(route_hop.short_channel_id);
 res = Some(FailureLearnings {
 network_update,
 short_channel_id,
 payment_failed_permanently: is_from_final_node,
 failed_within_blinded_path: false,
 });
 return;
 },
 };

 let error_code_slice = match err_packet.failuremsg.get(0..2) {
 Some(s) => s,
 None => {
 // Useless packet that we can't use but it passed HMAC, so it definitely came from the peer
 // in question
 log_warn!(logger, "Missing error code in failure from {}", route_hop.pubkey);

 let network_update = Some(NetworkUpdate::NodeFailure {
 node_id: route_hop.pubkey,
 is_permanent: true,
Expand DownExpand Up@@ -1219,6 +1239,12 @@ where
	} else {
 // only not set either packet unparseable or hmac does not match with any
 // payment not retryable only when garbage is from the final node
 log_warn!(
 logger,
 "Non-attributable failure encountered on route {}",
 path.hops.iter().map(|h| h.pubkey.to_string()).collect::<Vec<_>>().join("->")
 );

 DecodedOnionFailure {
 network_update: None,
 short_channel_id: None,
Expand DownExpand Up@@ -1764,7 +1790,10 @@ fn decode_next_hop<T, R: ReadableArgs<T>, N: NextPacketBytes>(

#[cfg(test)]
mod tests {
	use std::sync::Arc;

	use crate::io;
	use crate::ln::channelmanager::PaymentId;
	use crate::ln::msgs;
	use crate::routing::router::{Path, PaymentParameters, Route, RouteHop};
	use crate::types::features::{ChannelFeatures, NodeFeatures};
Expand All@@ -1773,6 +1802,7 @@ mod tests {

	#[allow(unused_imports)]
	use crate::prelude::*;
	use crate::util::test_utils::TestLogger;

	use bitcoin::hex::FromHex;
	use bitcoin::secp256k1::Secp256k1;
Expand All@@ -1785,40 +1815,95 @@ mod tests {
 SecretKey::from_slice(&<Vec<u8>>::from_hex(hex).unwrap()[..]).unwrap()
	}

	fn build_test_path() -> Path {
 Path {
 hops: vec![
 RouteHop {
@joostjagerjoostjagerFeb 28, 2025

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rustfmt wanted this
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 0,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 1,
@joostjagerjoostjagerFeb 28, 2025

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it is a move, but just these short_channel_id's made unique to make it easier to test things for attr errors
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 2,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 3,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(
 &<Vec<u8>>::from_hex(
 "02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145",
 )
 .unwrap()[..],
 )
 .unwrap(),
 channel_features: ChannelFeatures::empty(),
 node_features: NodeFeatures::empty(),
 short_channel_id: 4,
 fee_msat: 0,
 cltv_expiry_delta: 0,
 maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ],
 blinded_tail: None,
 }
	}

	fn build_test_onion_keys() -> Vec<OnionKeys> {
 // Keys from BOLT 4, used in both test vector tests
 let secp_ctx = Secp256k1::new();

 let route = Route {
 paths: vec![Path { hops: vec![
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 RouteHop {
 pubkey: PublicKey::from_slice(&<Vec<u8>>::from_hex("02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145").unwrap()[..]).unwrap(),
 channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
 short_channel_id: 0, fee_msat: 0, cltv_expiry_delta: 0, maybe_announced_channel: true, // We fill in the payloads manually instead of generating them from RouteHops.
 },
 ], blinded_tail: None }],
 route_params: None,
 };
 let path = build_test_path();
 let route = Route { paths: vec![path], route_params: None };

 let onion_keys =
 super::construct_onion_keys(&secp_ctx, &route.paths[0], &get_test_session_key())
Expand DownExpand Up@@ -2078,6 +2163,108 @@ mod tests {
 );
 let hex = "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";
 assert_eq!(onion_packet_5.data, <Vec<u8>>::from_hex(hex).unwrap());

 let logger: Arc<TestLogger> = Arc::new(TestLogger::new());
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 // Assert that the original failure can be retrieved and that all hmacs check out.
 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, onion_packet_5.data);

 assert_eq!(decrypted_failure.onion_error_code, Some(0x2002));
	}

	#[test]
	fn test_non_attributable_failure_packet_onion() {
 // Create a failure packet with bogus data.
 let packet = vec![1u8; 292];

 // In the current protocol, it is unfortunately not possible to identify the failure source.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet);
 assert_eq!(decrypted_failure.short_channel_id, None);

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Non-attributable failure encountered",
 1,
 );
	}

	#[test]
	fn test_unreadable_failure_packet_onion() {
 // Create a failure packet with a valid hmac but unreadable failure message.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 // The failure message is a single 0 byte.
 let mut packet = [0u8; 33];

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet[32..]);
 let hmac = Hmac::from_engine(hmac).to_byte_array();
 packet[..32].copy_from_slice(&hmac);

 let packet = encrypt_failure_packet(shared_secret, &packet);

 // For the unreadable failure, it is still expected that the failing channel can be identified.
 let logger: TestLogger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains("lightning::ln::onion_utils", "Unreadable failure", 1);
	}

	#[test]
	fn test_missing_error_code() {
 // Create a failure packet with a valid hmac and structure, but no error code.
 let onion_keys: Vec<OnionKeys> = build_test_onion_keys();
 let shared_secret = onion_keys[0].shared_secret.as_ref();
 let um = gen_um_from_shared_secret(&shared_secret);

 let failuremsg = vec![1];
 let pad = Vec::new();
 let mut packet = msgs::DecodedOnionErrorPacket { hmac: [0; 32], failuremsg, pad };

 let mut hmac = HmacEngine::<Sha256>::new(&um);
 hmac.input(&packet.encode()[32..]);
 packet.hmac = Hmac::from_engine(hmac).to_byte_array();

 let packet = encrypt_failure_packet(shared_secret, &packet.encode()[..]);

 let logger = TestLogger::new();
 let decrypted_failure = test_failure_attribution(&logger, &packet.data);
 assert_eq!(decrypted_failure.short_channel_id, Some(0));

 logger.assert_log_contains(
 "lightning::ln::onion_utils",
 "Missing error code in failure",
 1,
 );
	}

	fn test_failure_attribution(logger: &TestLogger, packet: &[u8]) -> DecodedOnionFailure {
 let ctx_full = Secp256k1::new();
 let path = build_test_path();
 let htlc_source = HTLCSource::OutboundRoute {
 path,
 session_priv: get_test_session_key(),
 first_hop_htlc_msat: 0,
 payment_id: PaymentId([1; 32]),
 };

 let decrypted_failure =
 process_onion_failure(&ctx_full, &logger, &htlc_source, packet.into());

 decrypted_failure
	}

	struct RawOnionHopData {
Expand Down