+
+// Uses the provided secret to simultaneously decode and decrypt the control TLVs and data TLV.
+impl<H: CustomOnionMessageHandler + ?Sized, L: Logger + ?Sized>
+ReadableArgs<(SharedSecret, &H, &L)> for Payload<<H as CustomOnionMessageHandler>::CustomMessage> {
+ fn read<R: Read>(r: &mut R, args: (SharedSecret, &H, &L)) -> Result<Self, DecodeError> {
+ let (encrypted_tlvs_ss, handler, logger) = 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 msg_type {
+ tlv_type if OffersMessage::is_known_type(tlv_type) => {
+ let msg = OffersMessage::read(msg_reader, (tlv_type, logger))?;
+ message = Some(OnionMessageContents::Offers(msg));
+ Ok(true)
+ },
+ _ => match handler.read_custom_message(msg_type, msg_reader)? {
+ Some(msg) => {
+ message = Some(OnionMessageContents::Custom(msg));
+ Ok(true)
+ },
+ None => Ok(false),
+ },
+ }
+ });
+ 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)}) => {
+ Ok(Payload::Receive {
+ control_tlvs: ReceiveControlTlvs::Unblinded(tlvs),
+ reply_path,
+ message: message.ok_or(DecodeError::InvalidValue)?,
+ })
+ },
+ }
+ }
+}
+
+/// 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 [`ForwardTlvs`] or
+/// [`ReceiveTlvs`] directly. Also useful on the encoding side to keep forward and receive TLVs in
+/// the same iterator.
+pub(crate) 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>(r: &mut R) -> Result<Self, DecodeError> {
+ _init_and_read_tlv_stream!(r, {
+ (1, _padding, option),
+ (2, _short_channel_id, option),
+ (4, next_node_id, option),
+ (6, path_id, option),
+ (8, next_blinding_override, option),
+ });
+ let _padding: Option<Padding> = _padding;
+ let _short_channel_id: Option<u64> = _short_channel_id;
+
+ 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)
+ }
+}
+
+impl Writeable for ControlTlvs {
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ match self {
+ Self::Forward(tlvs) => tlvs.write(w),
+ Self::Receive(tlvs) => tlvs.write(w),
+ }
+ }
+}