+
+/// Onion message payloads contain "control" TLVs and "data" TLVs. Control TLVs are used to route
+/// the onion message from hop to hop and for path verification, whereas data TLVs contain the onion
+/// message content itself, such as an invoice request.
+pub(super) enum Payload<T: CustomOnionMessageContents> {
+ /// This payload is for an intermediate hop.
+ Forward(ForwardControlTlvs),
+ /// This payload is for the final hop.
+ Receive {
+ control_tlvs: ReceiveControlTlvs,
+ reply_path: Option<BlindedPath>,
+ message: OnionMessageContents<T>,
+ }
+}
+
+#[derive(Debug)]
+/// The contents of an onion message. In the context of offers, this would be the invoice, invoice
+/// request, or invoice error.
+pub enum OnionMessageContents<T: CustomOnionMessageContents> {
+ /// A message related to BOLT 12 Offers.
+ Offers(OffersMessage),
+ /// A custom onion message specified by the user.
+ Custom(T),
+}
+
+impl<T: CustomOnionMessageContents> OnionMessageContents<T> {
+ /// Returns the type that was used to decode the message payload.
+ ///
+ /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
+ pub fn tlv_type(&self) -> u64 {
+ match self {
+ &OnionMessageContents::Offers(ref msg) => msg.tlv_type(),
+ &OnionMessageContents::Custom(ref msg) => msg.tlv_type(),
+ }
+ }
+}
+
+/// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
+impl<T: CustomOnionMessageContents> Writeable for OnionMessageContents<T> {
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ match self {
+ OnionMessageContents::Offers(msg) => Ok(msg.write(w)?),
+ OnionMessageContents::Custom(msg) => Ok(msg.write(w)?),
+ }
+ }
+}
+
+/// The contents of a custom onion message.
+pub trait CustomOnionMessageContents: Writeable {
+ /// Returns the TLV type identifying the message contents. MUST be >= 64.
+ fn tlv_type(&self) -> u64;
+}
+
+/// Forward control TLVs in their blinded and unblinded form.
+pub(super) enum ForwardControlTlvs {
+ /// If we're sending to a blinded path, the node that constructed the blinded path has provided
+ /// this hop's control TLVs, already encrypted into bytes.
+ Blinded(Vec<u8>),
+ /// If we're constructing an onion message hop through an intermediate unblinded node, we'll need
+ /// to construct the intermediate hop's control TLVs in their unblinded state to avoid encoding
+ /// them into an intermediate Vec. See [`crate::blinded_path::ForwardTlvs`] for more info.
+ Unblinded(ForwardTlvs),
+}
+
+/// Receive control TLVs in their blinded and unblinded form.
+pub(super) enum ReceiveControlTlvs {
+ /// See [`ForwardControlTlvs::Blinded`].
+ Blinded(Vec<u8>),
+ /// See [`ForwardControlTlvs::Unblinded`] and [`crate::blinded_path::ReceiveTlvs`].
+ Unblinded(ReceiveTlvs),
+}
+
+// Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
+impl<T: CustomOnionMessageContents> Writeable for (Payload<T>, [u8; 32]) {
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ match &self.0 {
+ Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) => {
+ _encode_varint_length_prefixed_tlv!(w, {
+ (4, *encrypted_bytes, required_vec)
+ })
+ },
+ Payload::Receive {
+ control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes), reply_path, message,
+ } => {
+ _encode_varint_length_prefixed_tlv!(w, {
+ (2, reply_path, option),
+ (4, *encrypted_bytes, required_vec),
+ (message.tlv_type(), message, required)
+ })
+ },
+ Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
+ let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
+ _encode_varint_length_prefixed_tlv!(w, {
+ (4, write_adapter, required)
+ })
+ },
+ Payload::Receive {
+ control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs), reply_path, message,
+ } => {
+ let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
+ _encode_varint_length_prefixed_tlv!(w, {
+ (2, reply_path, option),
+ (4, write_adapter, required),
+ (message.tlv_type(), message, required)
+ })
+ },
+ }
+ Ok(())
+ }
+}
+
+// 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 ForwardControlTlvs or
+/// ReceiveControlTlvs directly.
+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>(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 {})
+ }
+}