Give us a self when reading a custom onion message

[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 598edcf0367952b011e290bfe48938ec92364ecb..953313955a50220ed9b7d9693897facc35fbf7e6 100644 (file)
--- a/lightning/src/ln/onion_utils.rs
+++ b/lightning/src/ln/onion_utils.rs
@@ -589,31 +589,6 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(secp_ctx: &
        } else { unreachable!(); }
 }
 
-/// An input used when decoding an onion packet.
-pub(crate) trait DecodeInput {
-       type Arg;
-       /// If Some, this is the input when checking the hmac of the onion packet.
-       fn payment_hash(&self) -> Option<&PaymentHash>;
-       /// Read argument when decrypting our hop payload.
-       fn read_arg(self) -> Self::Arg;
-}
-
-impl DecodeInput for PaymentHash {
-       type Arg = ();
-       fn payment_hash(&self) -> Option<&PaymentHash> {
-               Some(self)
-       }
-       fn read_arg(self) -> Self::Arg { () }
-}
-
-impl DecodeInput for SharedSecret {
-       type Arg = SharedSecret;
-       fn payment_hash(&self) -> Option<&PaymentHash> {
-               None
-       }
-       fn read_arg(self) -> Self::Arg { self }
-}
-
 /// Allows `decode_next_hop` to return the next hop packet bytes for either payments or onion
 /// message forwards.
 pub(crate) trait NextPacketBytes: AsMut<[u8]> {
@@ -664,7 +639,7 @@ pub(crate) enum OnionDecodeErr {
 }
 
 pub(crate) fn decode_next_payment_hop(shared_secret: [u8; 32], hop_data: &[u8], hmac_bytes: [u8; 32], payment_hash: PaymentHash) -> Result<Hop, OnionDecodeErr> {
-       match decode_next_hop(shared_secret, hop_data, hmac_bytes, payment_hash) {
+       match decode_next_hop(shared_secret, hop_data, hmac_bytes, Some(payment_hash), ()) {
                Ok((next_hop_data, None)) => Ok(Hop::Receive(next_hop_data)),
                Ok((next_hop_data, Some((next_hop_hmac, FixedSizeOnionPacket(new_packet_bytes))))) => {
                        Ok(Hop::Forward {
@@ -677,12 +652,16 @@ pub(crate) fn decode_next_payment_hop(shared_secret: [u8; 32], hop_data: &[u8],
        }
 }
 
-pub(crate) fn decode_next_hop<D: DecodeInput, R: ReadableArgs<D::Arg>, N: NextPacketBytes>(shared_secret: [u8; 32], hop_data: &[u8], hmac_bytes: [u8; 32], decode_input: D) -> Result<(R, Option<([u8; 32], N)>), OnionDecodeErr> {
+pub(crate) fn decode_next_untagged_hop<T, R: ReadableArgs<T>, N: NextPacketBytes>(shared_secret: [u8; 32], hop_data: &[u8], hmac_bytes: [u8; 32], read_args: T) -> Result<(R, Option<([u8; 32], N)>), OnionDecodeErr> {
+       decode_next_hop(shared_secret, hop_data, hmac_bytes, None, read_args)
+}
+
+fn decode_next_hop<T, R: ReadableArgs<T>, N: NextPacketBytes>(shared_secret: [u8; 32], hop_data: &[u8], hmac_bytes: [u8; 32], payment_hash: Option<PaymentHash>, read_args: T) -> Result<(R, Option<([u8; 32], N)>), OnionDecodeErr> {
        let (rho, mu) = gen_rho_mu_from_shared_secret(&shared_secret);
        let mut hmac = HmacEngine::<Sha256>::new(&mu);
        hmac.input(hop_data);
-       if let Some(payment_hash) = decode_input.payment_hash() {
-               hmac.input(&payment_hash.0[..]);
+       if let Some(tag) = payment_hash {
+               hmac.input(&tag.0[..]);
        }
        if !fixed_time_eq(&Hmac::from_engine(hmac).into_inner(), &hmac_bytes) {
                return Err(OnionDecodeErr::Malformed {
@@ -693,7 +672,7 @@ pub(crate) fn decode_next_hop<D: DecodeInput, R: ReadableArgs<D::Arg>, N: NextPa
 
        let mut chacha = ChaCha20::new(&rho, &[0u8; 8]);
        let mut chacha_stream = ChaChaReader { chacha: &mut chacha, read: Cursor::new(&hop_data[..]) };
-       match R::read(&mut chacha_stream, decode_input.read_arg()) {
+       match R::read(&mut chacha_stream, read_args) {
                Err(err) => {
                        let error_code = match err {
                                msgs::DecodeError::UnknownVersion => 0x4000 | 1, // unknown realm byte