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 crate::util::chacha20poly1305rfc::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
20 use crate::util::logger::Logger;
21 use crate::util::ser::{BigSize, FixedLengthReader, LengthRead, LengthReadable, LengthReadableArgs, Readable, ReadableArgs, Writeable, Writer};
24 use crate::io::{self, Read};
25 use crate::prelude::*;
27 // Per the spec, an onion message packet's `hop_data` field length should be
28 // SMALL_PACKET_HOP_DATA_LEN if it fits, else BIG_PACKET_HOP_DATA_LEN if it fits.
29 pub(super) const SMALL_PACKET_HOP_DATA_LEN: usize = 1300;
30 pub(super) const BIG_PACKET_HOP_DATA_LEN: usize = 32768;
32 #[derive(Clone, Debug, PartialEq, Eq)]
33 pub(crate) struct Packet {
34 pub(super) version: u8,
35 pub(super) public_key: PublicKey,
36 // Unlike the onion packets used for payments, onion message packets can have payloads greater
38 // TODO: if 1300 ends up being the most common size, optimize this to be:
39 // enum { ThirteenHundred([u8; 1300]), VarLen(Vec<u8>) }
40 pub(super) hop_data: Vec<u8>,
41 pub(super) hmac: [u8; 32],
44 impl onion_utils::Packet for Packet {
46 fn new(public_key: PublicKey, hop_data: Vec<u8>, hmac: [u8; 32]) -> Packet {
56 impl Writeable for Packet {
57 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
58 self.version.write(w)?;
59 self.public_key.write(w)?;
60 w.write_all(&self.hop_data)?;
66 impl LengthReadable for Packet {
67 fn read<R: LengthRead>(r: &mut R) -> Result<Self, DecodeError> {
68 const READ_BUFFER_SIZE: usize = 4096;
70 let version = Readable::read(r)?;
71 let public_key = Readable::read(r)?;
73 let mut hop_data = Vec::new();
74 let hop_data_len = r.total_bytes().saturating_sub(66) as usize; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
76 while read_idx < hop_data_len {
77 let mut read_buffer = [0; READ_BUFFER_SIZE];
78 let read_amt = cmp::min(hop_data_len - read_idx, READ_BUFFER_SIZE);
79 r.read_exact(&mut read_buffer[..read_amt])?;
80 hop_data.extend_from_slice(&read_buffer[..read_amt]);
84 let hmac = Readable::read(r)?;
94 /// Onion message payloads contain "control" TLVs and "data" TLVs. Control TLVs are used to route
95 /// the onion message from hop to hop and for path verification, whereas data TLVs contain the onion
96 /// message content itself, such as an invoice request.
97 pub(super) enum Payload<T: CustomOnionMessageContents> {
98 /// This payload is for an intermediate hop.
99 Forward(ForwardControlTlvs),
100 /// This payload is for the final hop.
102 control_tlvs: ReceiveControlTlvs,
103 reply_path: Option<BlindedPath>,
104 message: OnionMessageContents<T>,
109 /// The contents of an onion message. In the context of offers, this would be the invoice, invoice
110 /// request, or invoice error.
111 pub enum OnionMessageContents<T: CustomOnionMessageContents> {
116 /// A custom onion message specified by the user.
120 impl<T: CustomOnionMessageContents> OnionMessageContents<T> {
121 /// Returns the type that was used to decode the message payload.
123 /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
124 pub fn tlv_type(&self) -> u64 {
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::Custom(msg) => Ok(msg.write(w)?),
140 /// The contents of a custom onion message.
141 pub trait CustomOnionMessageContents: Writeable {
142 /// Returns the TLV type identifying the message contents. MUST be >= 64.
143 fn tlv_type(&self) -> u64;
146 /// Forward control TLVs in their blinded and unblinded form.
147 pub(super) enum ForwardControlTlvs {
148 /// If we're sending to a blinded path, the node that constructed the blinded path has provided
149 /// this hop's control TLVs, already encrypted into bytes.
151 /// If we're constructing an onion message hop through an intermediate unblinded node, we'll need
152 /// to construct the intermediate hop's control TLVs in their unblinded state to avoid encoding
153 /// them into an intermediate Vec. See [`crate::blinded_path::ForwardTlvs`] for more info.
154 Unblinded(ForwardTlvs),
157 /// Receive control TLVs in their blinded and unblinded form.
158 pub(super) enum ReceiveControlTlvs {
159 /// See [`ForwardControlTlvs::Blinded`].
161 /// See [`ForwardControlTlvs::Unblinded`] and [`crate::blinded_path::ReceiveTlvs`].
162 Unblinded(ReceiveTlvs),
165 // Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
166 impl<T: CustomOnionMessageContents> Writeable for (Payload<T>, [u8; 32]) {
167 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
169 Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) => {
170 _encode_varint_length_prefixed_tlv!(w, {
171 (4, *encrypted_bytes, vec_type)
175 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes), reply_path, message,
177 _encode_varint_length_prefixed_tlv!(w, {
178 (2, reply_path, option),
179 (4, *encrypted_bytes, vec_type),
180 (message.tlv_type(), message, required)
183 Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
184 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
185 _encode_varint_length_prefixed_tlv!(w, {
186 (4, write_adapter, required)
190 control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs), reply_path, message,
192 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
193 _encode_varint_length_prefixed_tlv!(w, {
194 (2, reply_path, option),
195 (4, write_adapter, required),
196 (message.tlv_type(), message, required)
204 // Uses the provided secret to simultaneously decode and decrypt the control TLVs and data TLV.
205 impl<H: CustomOnionMessageHandler, L: Logger>
206 ReadableArgs<(SharedSecret, &H, &L)> for Payload<<H as CustomOnionMessageHandler>::CustomMessage> {
207 fn read<R: Read>(r: &mut R, args: (SharedSecret, &H, &L)) -> Result<Self, DecodeError> {
208 let (encrypted_tlvs_ss, handler, _logger) = args;
210 let v: BigSize = Readable::read(r)?;
211 let mut rd = FixedLengthReader::new(r, v.0);
212 let mut reply_path: Option<BlindedPath> = None;
213 let mut read_adapter: Option<ChaChaPolyReadAdapter<ControlTlvs>> = None;
214 let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes());
215 let mut message_type: Option<u64> = None;
216 let mut message = None;
217 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
218 (2, reply_path, option),
219 (4, read_adapter, (option: LengthReadableArgs, rho)),
220 }, |msg_type, msg_reader| {
221 if msg_type < 64 { return Ok(false) }
222 // Don't allow reading more than one data TLV from an onion message.
223 if message_type.is_some() { return Err(DecodeError::InvalidValue) }
225 message_type = Some(msg_type);
226 match handler.read_custom_message(msg_type, msg_reader) {
231 Ok(None) => Ok(false),
235 rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
238 None => return Err(DecodeError::InvalidValue),
239 Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(tlvs)}) => {
240 if message_type.is_some() {
241 return Err(DecodeError::InvalidValue)
243 Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
245 Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs)}) => {
246 if message.is_none() { return Err(DecodeError::InvalidValue) }
247 Ok(Payload::Receive {
248 control_tlvs: ReceiveControlTlvs::Unblinded(tlvs),
250 message: OnionMessageContents::Custom(message.unwrap()),
257 /// When reading a packet off the wire, we don't know a priori whether the packet is to be forwarded
258 /// or received. Thus we read a ControlTlvs rather than reading a ForwardControlTlvs or
259 /// ReceiveControlTlvs directly.
260 pub(crate) enum ControlTlvs {
261 /// This onion message is intended to be forwarded.
262 Forward(ForwardTlvs),
263 /// This onion message is intended to be received.
264 Receive(ReceiveTlvs),
267 impl Readable for ControlTlvs {
268 fn read<R: Read>(mut r: &mut R) -> Result<Self, DecodeError> {
269 let mut _padding: Option<Padding> = None;
270 let mut _short_channel_id: Option<u64> = None;
271 let mut next_node_id: Option<PublicKey> = None;
272 let mut path_id: Option<[u8; 32]> = None;
273 let mut next_blinding_override: Option<PublicKey> = None;
274 decode_tlv_stream!(&mut r, {
275 (1, _padding, option),
276 (2, _short_channel_id, option),
277 (4, next_node_id, option),
278 (6, path_id, option),
279 (8, next_blinding_override, option),
282 let valid_fwd_fmt = next_node_id.is_some() && path_id.is_none();
283 let valid_recv_fmt = next_node_id.is_none() && next_blinding_override.is_none();
285 let payload_fmt = if valid_fwd_fmt {
286 ControlTlvs::Forward(ForwardTlvs {
287 next_node_id: next_node_id.unwrap(),
288 next_blinding_override,
290 } else if valid_recv_fmt {
291 ControlTlvs::Receive(ReceiveTlvs {
295 return Err(DecodeError::InvalidValue)
302 /// Reads padding to the end, ignoring what's read.
303 pub(crate) struct Padding {}
304 impl Readable for Padding {
306 fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
308 let mut buf = [0; 8192];
309 if reader.read(&mut buf[..])? == 0 { break; }