1 // This file is Copyright its original authors, visible in version control
4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
7 // You may not use this file except in accordance with one or both of these
10 //! Structs and enums useful for constructing and reading an onion message packet.
12 use bitcoin::secp256k1::PublicKey;
13 use bitcoin::secp256k1::ecdh::SharedSecret;
15 use crate::blinded_path::BlindedPath;
16 use crate::blinded_path::message::{ForwardTlvs, ReceiveTlvs};
17 use crate::blinded_path::utils::Padding;
18 use crate::ln::msgs::DecodeError;
19 use crate::ln::onion_utils;
20 use super::messenger::CustomOnionMessageHandler;
21 use super::offers::OffersMessage;
22 use crate::util::chacha20poly1305rfc::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
23 use crate::util::logger::Logger;
24 use crate::util::ser::{BigSize, FixedLengthReader, LengthRead, LengthReadable, LengthReadableArgs, Readable, ReadableArgs, Writeable, Writer};
27 use crate::io::{self, Read};
28 use crate::prelude::*;
30 // Per the spec, an onion message packet's `hop_data` field length should be
31 // SMALL_PACKET_HOP_DATA_LEN if it fits, else BIG_PACKET_HOP_DATA_LEN if it fits.
32 pub(super) const SMALL_PACKET_HOP_DATA_LEN: usize = 1300;
33 pub(super) const BIG_PACKET_HOP_DATA_LEN: usize = 32768;
35 #[derive(Clone, Debug, PartialEq, Eq)]
36 pub(crate) struct Packet {
37 pub(super) version: u8,
38 pub(super) public_key: PublicKey,
39 // Unlike the onion packets used for payments, onion message packets can have payloads greater
41 // TODO: if 1300 ends up being the most common size, optimize this to be:
42 // enum { ThirteenHundred([u8; 1300]), VarLen(Vec<u8>) }
43 pub(super) hop_data: Vec<u8>,
44 pub(super) hmac: [u8; 32],
47 impl onion_utils::Packet for Packet {
49 fn new(public_key: PublicKey, hop_data: Vec<u8>, hmac: [u8; 32]) -> Packet {
59 impl Writeable for Packet {
60 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
61 self.version.write(w)?;
62 self.public_key.write(w)?;
63 w.write_all(&self.hop_data)?;
69 impl LengthReadable for Packet {
70 fn read<R: LengthRead>(r: &mut R) -> Result<Self, DecodeError> {
71 const READ_BUFFER_SIZE: usize = 4096;
73 let version = Readable::read(r)?;
74 let public_key = Readable::read(r)?;
76 let mut hop_data = Vec::new();
77 let hop_data_len = r.total_bytes().saturating_sub(66) as usize; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
79 while read_idx < hop_data_len {
80 let mut read_buffer = [0; READ_BUFFER_SIZE];
81 let read_amt = cmp::min(hop_data_len - read_idx, READ_BUFFER_SIZE);
82 r.read_exact(&mut read_buffer[..read_amt])?;
83 hop_data.extend_from_slice(&read_buffer[..read_amt]);
87 let hmac = Readable::read(r)?;
97 /// Onion message payloads contain "control" TLVs and "data" TLVs. Control TLVs are used to route
98 /// the onion message from hop to hop and for path verification, whereas data TLVs contain the onion
99 /// message content itself, such as an invoice request.
100 pub(super) enum Payload<T: CustomOnionMessageContents> {
101 /// This payload is for an intermediate hop.
102 Forward(ForwardControlTlvs),
103 /// This payload is for the final hop.
105 control_tlvs: ReceiveControlTlvs,
106 reply_path: Option<BlindedPath>,
107 message: OnionMessageContents<T>,
112 /// The contents of an onion message. In the context of offers, this would be the invoice, invoice
113 /// request, or invoice error.
114 pub enum OnionMessageContents<T: CustomOnionMessageContents> {
115 /// A message related to BOLT 12 Offers.
116 Offers(OffersMessage),
117 /// A custom onion message specified by the user.
121 impl<T: CustomOnionMessageContents> OnionMessageContents<T> {
122 /// Returns the type that was used to decode the message payload.
124 /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
125 pub fn tlv_type(&self) -> u64 {
127 &OnionMessageContents::Offers(ref msg) => msg.tlv_type(),
128 &OnionMessageContents::Custom(ref msg) => msg.tlv_type(),
133 /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
134 impl<T: CustomOnionMessageContents> Writeable for OnionMessageContents<T> {
135 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
137 OnionMessageContents::Offers(msg) => Ok(msg.write(w)?),
138 OnionMessageContents::Custom(msg) => Ok(msg.write(w)?),
143 /// The contents of a custom onion message.
144 pub trait CustomOnionMessageContents: Writeable {
145 /// Returns the TLV type identifying the message contents. MUST be >= 64.
146 fn tlv_type(&self) -> u64;
149 /// Forward control TLVs in their blinded and unblinded form.
150 pub(super) enum ForwardControlTlvs {
151 /// If we're sending to a blinded path, the node that constructed the blinded path has provided
152 /// this hop's control TLVs, already encrypted into bytes.
154 /// If we're constructing an onion message hop through an intermediate unblinded node, we'll need
155 /// to construct the intermediate hop's control TLVs in their unblinded state to avoid encoding
156 /// them into an intermediate Vec. See [`crate::blinded_path::message::ForwardTlvs`] for more
158 Unblinded(ForwardTlvs),
161 /// Receive control TLVs in their blinded and unblinded form.
162 pub(super) enum ReceiveControlTlvs {
163 /// See [`ForwardControlTlvs::Blinded`].
165 /// See [`ForwardControlTlvs::Unblinded`] and [`crate::blinded_path::message::ReceiveTlvs`].
166 Unblinded(ReceiveTlvs),
169 // Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
170 impl<T: CustomOnionMessageContents> Writeable for (Payload<T>, [u8; 32]) {
171 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
173 Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) => {
174 _encode_varint_length_prefixed_tlv!(w, {
175 (4, *encrypted_bytes, required_vec)
179 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes), reply_path, message,
181 _encode_varint_length_prefixed_tlv!(w, {
182 (2, reply_path, option),
183 (4, *encrypted_bytes, required_vec),
184 (message.tlv_type(), message, required)
187 Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
188 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
189 _encode_varint_length_prefixed_tlv!(w, {
190 (4, write_adapter, required)
194 control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs), reply_path, message,
196 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
197 _encode_varint_length_prefixed_tlv!(w, {
198 (2, reply_path, option),
199 (4, write_adapter, required),
200 (message.tlv_type(), message, required)
208 // Uses the provided secret to simultaneously decode and decrypt the control TLVs and data TLV.
209 impl<H: CustomOnionMessageHandler + ?Sized, L: Logger + ?Sized>
210 ReadableArgs<(SharedSecret, &H, &L)> for Payload<<H as CustomOnionMessageHandler>::CustomMessage> {
211 fn read<R: Read>(r: &mut R, args: (SharedSecret, &H, &L)) -> Result<Self, DecodeError> {
212 let (encrypted_tlvs_ss, handler, logger) = args;
214 let v: BigSize = Readable::read(r)?;
215 let mut rd = FixedLengthReader::new(r, v.0);
216 let mut reply_path: Option<BlindedPath> = None;
217 let mut read_adapter: Option<ChaChaPolyReadAdapter<ControlTlvs>> = None;
218 let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes());
219 let mut message_type: Option<u64> = None;
220 let mut message = None;
221 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
222 (2, reply_path, option),
223 (4, read_adapter, (option: LengthReadableArgs, rho)),
224 }, |msg_type, msg_reader| {
225 if msg_type < 64 { return Ok(false) }
226 // Don't allow reading more than one data TLV from an onion message.
227 if message_type.is_some() { return Err(DecodeError::InvalidValue) }
229 message_type = Some(msg_type);
231 tlv_type if OffersMessage::is_known_type(tlv_type) => {
232 let msg = OffersMessage::read(msg_reader, (tlv_type, logger))?;
233 message = Some(OnionMessageContents::Offers(msg));
236 _ => match handler.read_custom_message(msg_type, msg_reader)? {
238 message = Some(OnionMessageContents::Custom(msg));
245 rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
248 None => return Err(DecodeError::InvalidValue),
249 Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(tlvs)}) => {
250 if message_type.is_some() {
251 return Err(DecodeError::InvalidValue)
253 Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
255 Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs)}) => {
256 Ok(Payload::Receive {
257 control_tlvs: ReceiveControlTlvs::Unblinded(tlvs),
259 message: message.ok_or(DecodeError::InvalidValue)?,
266 /// When reading a packet off the wire, we don't know a priori whether the packet is to be forwarded
267 /// or received. Thus we read a `ControlTlvs` rather than reading a [`ForwardTlvs`] or
268 /// [`ReceiveTlvs`] directly. Also useful on the encoding side to keep forward and receive TLVs in
269 /// the same iterator.
270 pub(crate) enum ControlTlvs {
271 /// This onion message is intended to be forwarded.
272 Forward(ForwardTlvs),
273 /// This onion message is intended to be received.
274 Receive(ReceiveTlvs),
277 impl Readable for ControlTlvs {
278 fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
279 _init_and_read_tlv_stream!(r, {
280 (1, _padding, option),
281 (2, _short_channel_id, option),
282 (4, next_node_id, option),
283 (6, path_id, option),
284 (8, next_blinding_override, option),
286 let _padding: Option<Padding> = _padding;
287 let _short_channel_id: Option<u64> = _short_channel_id;
289 let valid_fwd_fmt = next_node_id.is_some() && path_id.is_none();
290 let valid_recv_fmt = next_node_id.is_none() && next_blinding_override.is_none();
292 let payload_fmt = if valid_fwd_fmt {
293 ControlTlvs::Forward(ForwardTlvs {
294 next_node_id: next_node_id.unwrap(),
295 next_blinding_override,
297 } else if valid_recv_fmt {
298 ControlTlvs::Receive(ReceiveTlvs {
302 return Err(DecodeError::InvalidValue)
309 impl Writeable for ControlTlvs {
310 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
312 Self::Forward(tlvs) => tlvs.write(w),
313 Self::Receive(tlvs) => tlvs.write(w),