Fix debug panic in onion utils on large custom TLVs or metadata.

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

diff --git a/lightning/src/ln/onion_utils.rs b/lightning/src/ln/onion_utils.rs
index 051e78c46eed51f14b4038119217d180ee40aff0..a9f8074f5c1bda36f06f78158b61e09f96d3318f 100644 (file)
--- a/lightning/src/ln/onion_utils.rs
+++ b/lightning/src/ln/onion_utils.rs
@@ -1021,18 +1021,20 @@ fn decode_next_hop<T, R: ReadableArgs<T>, N: NextPacketBytes>(shared_secret: [u8
                        if hmac == [0; 32] {
                                #[cfg(test)]
                                {
-                                       // In tests, make sure that the initial onion packet data is, at least, non-0.
-                                       // We could do some fancy randomness test here, but, ehh, whatever.
-                                       // This checks for the issue where you can calculate the path length given the
-                                       // onion data as all the path entries that the originator sent will be here
-                                       // as-is (and were originally 0s).
-                                       // Of course reverse path calculation is still pretty easy given naive routing
-                                       // algorithms, but this fixes the most-obvious case.
-                                       let mut next_bytes = [0; 32];
-                                       chacha_stream.read_exact(&mut next_bytes).unwrap();
-                                       assert_ne!(next_bytes[..], [0; 32][..]);
-                                       chacha_stream.read_exact(&mut next_bytes).unwrap();
-                                       assert_ne!(next_bytes[..], [0; 32][..]);
+                                       if chacha_stream.read.position() < hop_data.len() as u64 - 64 {
+                                               // In tests, make sure that the initial onion packet data is, at least, non-0.
+                                               // We could do some fancy randomness test here, but, ehh, whatever.
+                                               // This checks for the issue where you can calculate the path length given the
+                                               // onion data as all the path entries that the originator sent will be here
+                                               // as-is (and were originally 0s).
+                                               // Of course reverse path calculation is still pretty easy given naive routing
+                                               // algorithms, but this fixes the most-obvious case.
+                                               let mut next_bytes = [0; 32];
+                                               chacha_stream.read_exact(&mut next_bytes).unwrap();
+                                               assert_ne!(next_bytes[..], [0; 32][..]);
+                                               chacha_stream.read_exact(&mut next_bytes).unwrap();
+                                               assert_ne!(next_bytes[..], [0; 32][..]);
+                                       }
                                }
                                return Ok((msg, None)); // We are the final destination for this packet
                        } else {