Error if onion payloads exceed max length on packet construction.

[rust-lightning] / lightning / src / ln / onion_payment.rs

diff --git a/lightning/src/ln/onion_payment.rs b/lightning/src/ln/onion_payment.rs
index 07c08d57995b6938c78214067a54c9f7ae74c7b1..7c0d32a52a53bccab19177fa014b90e477cd317c 100644 (file)
--- a/lightning/src/ln/onion_payment.rs
+++ b/lightning/src/ln/onion_payment.rs
@@ -449,7 +449,7 @@ pub(super) fn check_incoming_htlc_cltv(
 mod tests {
        use bitcoin::hashes::Hash;
        use bitcoin::hashes::sha256::Hash as Sha256;
-       use bitcoin::secp256k1::{PublicKey, SecretKey};
+       use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
        use crate::ln::{PaymentPreimage, PaymentHash, PaymentSecret};
        use crate::ln::ChannelId;
        use crate::ln::channelmanager::RecipientOnionFields;
@@ -459,6 +459,38 @@ mod tests {
        use crate::routing::router::{Path, RouteHop};
        use crate::util::test_utils;
 
+       #[test]
+       fn fail_construct_onion_on_too_big_payloads() {
+               // Ensure that if we call `construct_onion_packet` and friends where payloads are too large for
+               // the allotted packet length, we'll fail to construct. Previously, senders would happily
+               // construct invalid packets by array-shifting the final node's HMAC out of the packet when
+               // adding an intermediate onion layer, causing the receiver to error with "final payload
+               // provided for us as an intermediate node."
+               let secp_ctx = Secp256k1::new();
+               let bob = crate::sign::KeysManager::new(&[2; 32], 42, 42);
+               let bob_pk = PublicKey::from_secret_key(&secp_ctx, &bob.get_node_secret_key());
+               let charlie = crate::sign::KeysManager::new(&[3; 32], 42, 42);
+               let charlie_pk = PublicKey::from_secret_key(&secp_ctx, &charlie.get_node_secret_key());
+
+               let (
+                       session_priv, total_amt_msat, cur_height, mut recipient_onion, keysend_preimage, payment_hash,
+                       prng_seed, hops, ..
+               ) = payment_onion_args(bob_pk, charlie_pk);
+
+               // Ensure the onion will not fit all the payloads by adding a large custom TLV.
+               recipient_onion.custom_tlvs.push((13377331, vec![0; 1156]));
+
+               let path = Path { hops, blinded_tail: None, };
+               let onion_keys = super::onion_utils::construct_onion_keys(&secp_ctx, &path, &session_priv).unwrap();
+               let (onion_payloads, ..) = super::onion_utils::build_onion_payloads(
+                       &path, total_amt_msat, recipient_onion, cur_height + 1, &Some(keysend_preimage)
+               ).unwrap();
+
+               assert!(super::onion_utils::construct_onion_packet(
+                               onion_payloads, onion_keys, prng_seed, &payment_hash
+               ).is_err());
+       }
+
        #[test]
        fn test_peel_payment_onion() {
                use super::*;