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 ln::msgs::DecodeError;
17 use super::blinded_route::{BlindedRoute, ForwardTlvs, ReceiveTlvs};
18 use util::chacha20poly1305rfc::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
19 use util::ser::{BigSize, FixedLengthReader, LengthRead, LengthReadable, LengthReadableArgs, MaybeReadableArgs, Readable, ReadableArgs, Writeable, Writer};
25 // Per the spec, an onion message packet's `hop_data` field length should be
26 // SMALL_PACKET_HOP_DATA_LEN if it fits, else BIG_PACKET_HOP_DATA_LEN if it fits.
27 pub(super) const SMALL_PACKET_HOP_DATA_LEN: usize = 1300;
28 pub(super) const BIG_PACKET_HOP_DATA_LEN: usize = 32768;
30 #[derive(Clone, Debug, PartialEq)]
31 pub(crate) struct Packet {
32 pub(super) version: u8,
33 pub(super) public_key: PublicKey,
34 // Unlike the onion packets used for payments, onion message packets can have payloads greater
36 // TODO: if 1300 ends up being the most common size, optimize this to be:
37 // enum { ThirteenHundred([u8; 1300]), VarLen(Vec<u8>) }
38 pub(super) hop_data: Vec<u8>,
39 pub(super) hmac: [u8; 32],
42 impl onion_utils::Packet for Packet {
44 fn new(public_key: PublicKey, hop_data: Vec<u8>, hmac: [u8; 32]) -> Packet {
54 impl Writeable for Packet {
55 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
56 self.version.write(w)?;
57 self.public_key.write(w)?;
58 w.write_all(&self.hop_data)?;
64 impl LengthReadable for Packet {
65 fn read<R: LengthRead>(r: &mut R) -> Result<Self, DecodeError> {
66 const READ_BUFFER_SIZE: usize = 4096;
68 let version = Readable::read(r)?;
69 let public_key = Readable::read(r)?;
71 let mut hop_data = Vec::new();
72 let hop_data_len = r.total_bytes().saturating_sub(66) as usize; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
74 while read_idx < hop_data_len {
75 let mut read_buffer = [0; READ_BUFFER_SIZE];
76 let read_amt = cmp::min(hop_data_len - read_idx, READ_BUFFER_SIZE);
77 r.read_exact(&mut read_buffer[..read_amt])?;
78 hop_data.extend_from_slice(&read_buffer[..read_amt]);
82 let hmac = Readable::read(r)?;
92 /// Onion message payloads contain "control" TLVs and "data" TLVs. Control TLVs are used to route
93 /// the onion message from hop to hop and for path verification, whereas data TLVs contain the onion
94 /// message content itself, such as an invoice request.
95 pub(super) enum Payload {
96 /// This payload is for an intermediate hop.
97 Forward(ForwardControlTlvs),
98 /// This payload is for the final hop.
100 control_tlvs: ReceiveControlTlvs,
101 reply_path: Option<BlindedRoute>,
108 /// The contents of an onion message. In the context of offers, this would be the invoice, invoice
109 /// request, or invoice error.
110 pub enum OnionMessageContents<T> where T: CustomOnionMessageContents {
115 /// A custom onion message specified by the user.
119 impl<T> OnionMessageContents<T> where T: CustomOnionMessageContents {
120 /// Returns the type that was used to decode the message payload.
121 pub fn tlv_type(&self) -> u64 {
123 &OnionMessageContents::Custom(ref msg) => msg.tlv_type(),
128 impl<T: CustomOnionMessageContents> Writeable for OnionMessageContents<T> {
129 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
131 OnionMessageContents::Custom(msg) => Ok(msg.write(w)?),
136 /// The contents of a custom onion message. Must implement `MaybeReadableArgs<u64>` where the `u64`
137 /// is the custom TLV type attempting to be read, and return `Ok(None)` if the TLV type is unknown.
138 pub trait CustomOnionMessageContents: Writeable + MaybeReadableArgs<u64> {
139 /// Returns the TLV type identifying the message contents. MUST be >= 64.
140 fn tlv_type(&self) -> u64;
143 /// Forward control TLVs in their blinded and unblinded form.
144 pub(super) enum ForwardControlTlvs {
145 /// If we're sending to a blinded route, the node that constructed the blinded route has provided
146 /// this hop's control TLVs, already encrypted into bytes.
148 /// If we're constructing an onion message hop through an intermediate unblinded node, we'll need
149 /// to construct the intermediate hop's control TLVs in their unblinded state to avoid encoding
150 /// them into an intermediate Vec. See [`super::blinded_route::ForwardTlvs`] for more info.
151 Unblinded(ForwardTlvs),
154 /// Receive control TLVs in their blinded and unblinded form.
155 pub(super) enum ReceiveControlTlvs {
156 /// See [`ForwardControlTlvs::Blinded`].
158 /// See [`ForwardControlTlvs::Unblinded`] and [`super::blinded_route::ReceiveTlvs`].
159 Unblinded(ReceiveTlvs),
162 // Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
163 impl Writeable for (Payload, [u8; 32]) {
164 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
166 Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) => {
167 encode_varint_length_prefixed_tlv!(w, {
168 (4, encrypted_bytes, vec_type)
172 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes), reply_path
174 encode_varint_length_prefixed_tlv!(w, {
175 (2, reply_path, option),
176 (4, encrypted_bytes, vec_type)
179 Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
180 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
181 encode_varint_length_prefixed_tlv!(w, {
182 (4, write_adapter, required)
186 control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs), reply_path,
188 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
189 encode_varint_length_prefixed_tlv!(w, {
190 (2, reply_path, option),
191 (4, write_adapter, required)
199 // Uses the provided secret to simultaneously decode and decrypt the control TLVs.
200 impl ReadableArgs<SharedSecret> for Payload {
201 fn read<R: Read>(r: &mut R, encrypted_tlvs_ss: SharedSecret) -> Result<Self, DecodeError> {
202 let v: BigSize = Readable::read(r)?;
203 let mut rd = FixedLengthReader::new(r, v.0);
204 let mut reply_path: Option<BlindedRoute> = None;
205 let mut read_adapter: Option<ChaChaPolyReadAdapter<ControlTlvs>> = None;
206 let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes());
207 decode_tlv_stream!(&mut rd, {
208 (2, reply_path, option),
209 (4, read_adapter, (option: LengthReadableArgs, rho))
211 rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
214 None => return Err(DecodeError::InvalidValue),
215 Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(tlvs)}) => {
216 Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
218 Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs)}) => {
219 Ok(Payload::Receive { control_tlvs: ReceiveControlTlvs::Unblinded(tlvs), reply_path })
225 /// When reading a packet off the wire, we don't know a priori whether the packet is to be forwarded
226 /// or received. Thus we read a ControlTlvs rather than reading a ForwardControlTlvs or
227 /// ReceiveControlTlvs directly.
228 pub(super) enum ControlTlvs {
229 /// This onion message is intended to be forwarded.
230 Forward(ForwardTlvs),
231 /// This onion message is intended to be received.
232 Receive(ReceiveTlvs),
235 impl Readable for ControlTlvs {
236 fn read<R: Read>(mut r: &mut R) -> Result<Self, DecodeError> {
237 let mut _padding: Option<Padding> = None;
238 let mut _short_channel_id: Option<u64> = None;
239 let mut next_node_id: Option<PublicKey> = None;
240 let mut path_id: Option<[u8; 32]> = None;
241 let mut next_blinding_override: Option<PublicKey> = None;
242 decode_tlv_stream!(&mut r, {
243 (1, _padding, option),
244 (2, _short_channel_id, option),
245 (4, next_node_id, option),
246 (6, path_id, option),
247 (8, next_blinding_override, option),
250 let valid_fwd_fmt = next_node_id.is_some() && path_id.is_none();
251 let valid_recv_fmt = next_node_id.is_none() && next_blinding_override.is_none();
253 let payload_fmt = if valid_fwd_fmt {
254 ControlTlvs::Forward(ForwardTlvs {
255 next_node_id: next_node_id.unwrap(),
256 next_blinding_override,
258 } else if valid_recv_fmt {
259 ControlTlvs::Receive(ReceiveTlvs {
263 return Err(DecodeError::InvalidValue)
270 /// Reads padding to the end, ignoring what's read.
271 pub(crate) struct Padding {}
272 impl Readable for Padding {
274 fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
276 let mut buf = [0; 8192];
277 if reader.read(&mut buf[..])? == 0 { break; }