+
+// Uses the provided secret to simultaneously decode and decrypt the control TLVs and data TLV.
+impl<H: CustomOnionMessageHandler> ReadableArgs<(SharedSecret, &H)> for Payload<<H as CustomOnionMessageHandler>::CustomMessage> {
+ fn read<R: Read>(r: &mut R, args: (SharedSecret, &H)) -> Result<Self, DecodeError> {
+ let (encrypted_tlvs_ss, handler) = args;
+
+ let v: BigSize = Readable::read(r)?;
+ let mut rd = FixedLengthReader::new(r, v.0);
+ let mut reply_path: Option<BlindedPath> = None;
+ let mut read_adapter: Option<ChaChaPolyReadAdapter<ControlTlvs>> = None;
+ let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes());
+ let mut message_type: Option<u64> = None;
+ let mut message = None;
+ decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
+ (2, reply_path, option),
+ (4, read_adapter, (option: LengthReadableArgs, rho)),
+ }, |msg_type, msg_reader| {
+ if msg_type < 64 { return Ok(false) }
+ // Don't allow reading more than one data TLV from an onion message.
+ if message_type.is_some() { return Err(DecodeError::InvalidValue) }
+
+ message_type = Some(msg_type);
+ match handler.read_custom_message(msg_type, msg_reader) {
+ Ok(Some(msg)) => {
+ message = Some(msg);
+ Ok(true)
+ },
+ Ok(None) => Ok(false),
+ Err(e) => Err(e),
+ }
+ });
+ rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
+
+ match read_adapter {
+ None => return Err(DecodeError::InvalidValue),
+ Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(tlvs)}) => {
+ if message_type.is_some() {
+ return Err(DecodeError::InvalidValue)
+ }
+ Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
+ },
+ Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs)}) => {
+ if message.is_none() { return Err(DecodeError::InvalidValue) }
+ Ok(Payload::Receive {
+ control_tlvs: ReceiveControlTlvs::Unblinded(tlvs),
+ reply_path,
+ message: OnionMessageContents::Custom(message.unwrap()),
+ })
+ }
+ }
+ }
+}
+
+/// When reading a packet off the wire, we don't know a priori whether the packet is to be forwarded
+/// or received. Thus we read a ControlTlvs rather than reading a ForwardControlTlvs or
+/// ReceiveControlTlvs directly.
+pub(super) enum ControlTlvs {
+ /// This onion message is intended to be forwarded.
+ Forward(ForwardTlvs),
+ /// This onion message is intended to be received.
+ Receive(ReceiveTlvs),
+}
+
+impl Readable for ControlTlvs {
+ fn read<R: Read>(mut r: &mut R) -> Result<Self, DecodeError> {
+ let mut _padding: Option<Padding> = None;
+ let mut _short_channel_id: Option<u64> = None;
+ let mut next_node_id: Option<PublicKey> = None;
+ let mut path_id: Option<[u8; 32]> = None;
+ let mut next_blinding_override: Option<PublicKey> = None;
+ decode_tlv_stream!(&mut r, {
+ (1, _padding, option),
+ (2, _short_channel_id, option),
+ (4, next_node_id, option),
+ (6, path_id, option),
+ (8, next_blinding_override, option),
+ });
+
+ let valid_fwd_fmt = next_node_id.is_some() && path_id.is_none();
+ let valid_recv_fmt = next_node_id.is_none() && next_blinding_override.is_none();
+
+ let payload_fmt = if valid_fwd_fmt {
+ ControlTlvs::Forward(ForwardTlvs {
+ next_node_id: next_node_id.unwrap(),
+ next_blinding_override,
+ })
+ } else if valid_recv_fmt {
+ ControlTlvs::Receive(ReceiveTlvs {
+ path_id,
+ })
+ } else {
+ return Err(DecodeError::InvalidValue)
+ };
+
+ Ok(payload_fmt)
+ }
+}
+
+/// Reads padding to the end, ignoring what's read.
+pub(crate) struct Padding {}
+impl Readable for Padding {
+ #[inline]
+ fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
+ loop {
+ let mut buf = [0; 8192];
+ if reader.read(&mut buf[..])? == 0 { break; }
+ }
+ Ok(Self {})
+ }
+}