X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Fonion_utils.rs;h=605080c7b9298798e45b1a9216f5bad62c810fd3;hb=ae15ba84620f40ed5c80870d254d5eda341f1aba;hp=31f2f7827bcb57c42d7b2a625a842abdaa00ab17;hpb=c2bbfffb1eb249c2c422cf2e9ccac97a34275f7a;p=rust-lightning

diff --git a/lightning/src/ln/onion_utils.rs b/lightning/src/ln/onion_utils.rs
index 31f2f782..605080c7 100644
--- a/lightning/src/ln/onion_utils.rs
+++ b/lightning/src/ln/onion_utils.rs
@@ -433,11 +433,22 @@ 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> {
+	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
 /// OutboundRoute).
 #[inline]
 pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(
-	secp_ctx: &Secp256k1<T>, logger: &L, htlc_source: &HTLCSource, mut packet_decrypted: Vec<u8>
+	secp_ctx: &Secp256k1<T>, logger: &L, htlc_source: &HTLCSource, mut encrypted_packet: Vec<u8>
 ) -> DecodedOnionFailure where L::Target: Logger {
 	let (path, session_priv, first_hop_htlc_msat) = if let &HTLCSource::OutboundRoute {
 		ref path, ref session_priv, ref first_hop_htlc_msat, ..
@@ -491,8 +502,21 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(
 				Some(hop) => hop,
 				None => {
 					// The failing hop is within a multi-hop blinded path.
-					error_code_ret = Some(BADONION | PERM | 24); // invalid_onion_blinding
-					error_packet_ret = Some(vec![0; 32]);
+					#[cfg(not(test))] {
+						error_code_ret = Some(BADONION | PERM | 24); // invalid_onion_blinding
+						error_packet_ret = Some(vec![0; 32]);
+					}
+					#[cfg(test)] {
+						// 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();
+						error_code_ret =
+							Some(u16::from_be_bytes(err_packet.failuremsg.get(0..2).unwrap().try_into().unwrap()));
+						error_packet_ret = Some(err_packet.failuremsg[2..].to_vec());
+					}
+
 					res = Some(FailureLearnings {
 						network_update: None, short_channel_id: None, payment_failed_permanently: false
 					});
@@ -504,15 +528,7 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(
 		let amt_to_forward = htlc_msat - route_hop.fee_msat;
 		htlc_msat = amt_to_forward;
 
-		let ammag = gen_ammag_from_shared_secret(shared_secret.as_ref());
-
-		let mut decryption_tmp = Vec::with_capacity(packet_decrypted.len());
-		decryption_tmp.resize(packet_decrypted.len(), 0);
-		let mut chacha = ChaCha20::new(&ammag, &[0u8; 8]);
-		chacha.process(&packet_decrypted, &mut decryption_tmp[..]);
-		packet_decrypted = decryption_tmp;
-
-		let err_packet = match msgs::DecodedOnionErrorPacket::read(&mut Cursor::new(&packet_decrypted)) {
+		let err_packet = match decrypt_onion_error_packet(&mut encrypted_packet, shared_secret) {
 			Ok(p) => p,
 			Err(_) => return
 		};