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, ForwardTlvs, ReceiveTlvs};
16 use crate::ln::msgs::DecodeError;
17 use crate::ln::onion_utils;
18 use super::messenger::CustomOnionMessageHandler;
19 use super::offers::OffersMessage;
20 use crate::util::chacha20poly1305rfc::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
21 use crate::util::logger::Logger;
22 use crate::util::ser::{BigSize, FixedLengthReader, LengthRead, LengthReadable, LengthReadableArgs, Readable, ReadableArgs, Writeable, Writer};
25 use crate::io::{self, Read};
26 use crate::prelude::*;
28 // Per the spec, an onion message packet's `hop_data` field length should be
29 // SMALL_PACKET_HOP_DATA_LEN if it fits, else BIG_PACKET_HOP_DATA_LEN if it fits.
30 pub(super) const SMALL_PACKET_HOP_DATA_LEN: usize = 1300;
31 pub(super) const BIG_PACKET_HOP_DATA_LEN: usize = 32768;
33 #[derive(Clone, Debug, PartialEq, Eq)]
34 pub(crate) struct Packet {
35 pub(super) version: u8,
36 pub(super) public_key: PublicKey,
37 // Unlike the onion packets used for payments, onion message packets can have payloads greater
39 // TODO: if 1300 ends up being the most common size, optimize this to be:
40 // enum { ThirteenHundred([u8; 1300]), VarLen(Vec<u8>) }
41 pub(super) hop_data: Vec<u8>,
42 pub(super) hmac: [u8; 32],
45 impl onion_utils::Packet for Packet {
47 fn new(public_key: PublicKey, hop_data: Vec<u8>, hmac: [u8; 32]) -> Packet {
57 impl Writeable for Packet {
58 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
59 self.version.write(w)?;
60 self.public_key.write(w)?;
61 w.write_all(&self.hop_data)?;
67 impl LengthReadable for Packet {
68 fn read<R: LengthRead>(r: &mut R) -> Result<Self, DecodeError> {
69 const READ_BUFFER_SIZE: usize = 4096;
71 let version = Readable::read(r)?;
72 let public_key = Readable::read(r)?;
74 let mut hop_data = Vec::new();
75 let hop_data_len = r.total_bytes().saturating_sub(66) as usize; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
77 while read_idx < hop_data_len {
78 let mut read_buffer = [0; READ_BUFFER_SIZE];
79 let read_amt = cmp::min(hop_data_len - read_idx, READ_BUFFER_SIZE);
80 r.read_exact(&mut read_buffer[..read_amt])?;
81 hop_data.extend_from_slice(&read_buffer[..read_amt]);
85 let hmac = Readable::read(r)?;
95 /// Onion message payloads contain "control" TLVs and "data" TLVs. Control TLVs are used to route
96 /// the onion message from hop to hop and for path verification, whereas data TLVs contain the onion
97 /// message content itself, such as an invoice request.
98 pub(super) enum Payload<T: CustomOnionMessageContents> {
99 /// This payload is for an intermediate hop.
100 Forward(ForwardControlTlvs),
101 /// This payload is for the final hop.
103 control_tlvs: ReceiveControlTlvs,
104 reply_path: Option<BlindedPath>,
105 message: OnionMessageContents<T>,
110 /// The contents of an onion message. In the context of offers, this would be the invoice, invoice
111 /// request, or invoice error.
112 pub enum OnionMessageContents<T: CustomOnionMessageContents> {
113 /// A message related to BOLT 12 Offers.
114 Offers(OffersMessage),
115 /// A custom onion message specified by the user.
119 impl<T: CustomOnionMessageContents> OnionMessageContents<T> {
120 /// Returns the type that was used to decode the message payload.
122 /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
123 pub fn tlv_type(&self) -> u64 {
125 &OnionMessageContents::Offers(ref msg) => msg.tlv_type(),
126 &OnionMessageContents::Custom(ref msg) => msg.tlv_type(),
131 /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
132 impl<T: CustomOnionMessageContents> Writeable for OnionMessageContents<T> {
133 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
135 OnionMessageContents::Offers(msg) => Ok(msg.write(w)?),
136 OnionMessageContents::Custom(msg) => Ok(msg.write(w)?),
141 /// The contents of a custom onion message.
142 pub trait CustomOnionMessageContents: Writeable {
143 /// Returns the TLV type identifying the message contents. MUST be >= 64.
144 fn tlv_type(&self) -> u64;
147 /// Forward control TLVs in their blinded and unblinded form.
148 pub(super) enum ForwardControlTlvs {
149 /// If we're sending to a blinded path, the node that constructed the blinded path has provided
150 /// this hop's control TLVs, already encrypted into bytes.
152 /// If we're constructing an onion message hop through an intermediate unblinded node, we'll need
153 /// to construct the intermediate hop's control TLVs in their unblinded state to avoid encoding
154 /// them into an intermediate Vec. See [`crate::blinded_path::ForwardTlvs`] for more info.
155 Unblinded(ForwardTlvs),
158 /// Receive control TLVs in their blinded and unblinded form.
159 pub(super) enum ReceiveControlTlvs {
160 /// See [`ForwardControlTlvs::Blinded`].
162 /// See [`ForwardControlTlvs::Unblinded`] and [`crate::blinded_path::ReceiveTlvs`].
163 Unblinded(ReceiveTlvs),
166 // Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
167 impl<T: CustomOnionMessageContents> Writeable for (Payload<T>, [u8; 32]) {
168 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
170 Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) => {
171 _encode_varint_length_prefixed_tlv!(w, {
172 (4, *encrypted_bytes, vec_type)
176 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes), reply_path, message,
178 _encode_varint_length_prefixed_tlv!(w, {
179 (2, reply_path, option),
180 (4, *encrypted_bytes, vec_type),
181 (message.tlv_type(), message, required)
184 Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
185 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
186 _encode_varint_length_prefixed_tlv!(w, {
187 (4, write_adapter, required)
191 control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs), reply_path, message,
193 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
194 _encode_varint_length_prefixed_tlv!(w, {
195 (2, reply_path, option),
196 (4, write_adapter, required),
197 (message.tlv_type(), message, required)
205 // Uses the provided secret to simultaneously decode and decrypt the control TLVs and data TLV.
206 impl<H: CustomOnionMessageHandler + ?Sized, L: Logger + ?Sized>
207 ReadableArgs<(SharedSecret, &H, &L)> for Payload<<H as CustomOnionMessageHandler>::CustomMessage> {
208 fn read<R: Read>(r: &mut R, args: (SharedSecret, &H, &L)) -> Result<Self, DecodeError> {
209 let (encrypted_tlvs_ss, handler, logger) = args;
211 let v: BigSize = Readable::read(r)?;
212 let mut rd = FixedLengthReader::new(r, v.0);
213 let mut reply_path: Option<BlindedPath> = None;
214 let mut read_adapter: Option<ChaChaPolyReadAdapter<ControlTlvs>> = None;
215 let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes());
216 let mut message_type: Option<u64> = None;
217 let mut message = None;
218 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
219 (2, reply_path, option),
220 (4, read_adapter, (option: LengthReadableArgs, rho)),
221 }, |msg_type, msg_reader| {
222 if msg_type < 64 { return Ok(false) }
223 // Don't allow reading more than one data TLV from an onion message.
224 if message_type.is_some() { return Err(DecodeError::InvalidValue) }
226 message_type = Some(msg_type);
228 tlv_type if OffersMessage::is_known_type(tlv_type) => {
229 let msg = OffersMessage::read(msg_reader, (tlv_type, logger))?;
230 message = Some(OnionMessageContents::Offers(msg));
233 _ => match handler.read_custom_message(msg_type, msg_reader)? {
235 message = Some(OnionMessageContents::Custom(msg));
242 rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
245 None => return Err(DecodeError::InvalidValue),
246 Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(tlvs)}) => {
247 if message_type.is_some() {
248 return Err(DecodeError::InvalidValue)
250 Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
252 Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs)}) => {
253 Ok(Payload::Receive {
254 control_tlvs: ReceiveControlTlvs::Unblinded(tlvs),
256 message: message.ok_or(DecodeError::InvalidValue)?,
263 /// When reading a packet off the wire, we don't know a priori whether the packet is to be forwarded
264 /// or received. Thus we read a ControlTlvs rather than reading a ForwardControlTlvs or
265 /// ReceiveControlTlvs directly.
266 pub(crate) enum ControlTlvs {
267 /// This onion message is intended to be forwarded.
268 Forward(ForwardTlvs),
269 /// This onion message is intended to be received.
270 Receive(ReceiveTlvs),
273 impl Readable for ControlTlvs {
274 fn read<R: Read>(mut r: &mut R) -> Result<Self, DecodeError> {
275 let mut _padding: Option<Padding> = None;
276 let mut _short_channel_id: Option<u64> = None;
277 let mut next_node_id: Option<PublicKey> = None;
278 let mut path_id: Option<[u8; 32]> = None;
279 let mut next_blinding_override: Option<PublicKey> = None;
280 decode_tlv_stream!(&mut r, {
281 (1, _padding, option),
282 (2, _short_channel_id, option),
283 (4, next_node_id, option),
284 (6, path_id, option),
285 (8, next_blinding_override, option),
288 let valid_fwd_fmt = next_node_id.is_some() && path_id.is_none();
289 let valid_recv_fmt = next_node_id.is_none() && next_blinding_override.is_none();
291 let payload_fmt = if valid_fwd_fmt {
292 ControlTlvs::Forward(ForwardTlvs {
293 next_node_id: next_node_id.unwrap(),
294 next_blinding_override,
296 } else if valid_recv_fmt {
297 ControlTlvs::Receive(ReceiveTlvs {
301 return Err(DecodeError::InvalidValue)
308 /// Reads padding to the end, ignoring what's read.
309 pub(crate) struct Padding {}
310 impl Readable for Padding {
312 fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
314 let mut buf = [0; 8192];
315 if reader.read(&mut buf[..])? == 0 { break; }