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, 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>,
109 // InvoiceRequest(InvoiceRequest),
111 // InvoiceError(InvoiceError),
115 /// Forward control TLVs in their blinded and unblinded form.
116 pub(super) enum ForwardControlTlvs {
117 /// If we're sending to a blinded route, the node that constructed the blinded route has provided
118 /// this hop's control TLVs, already encrypted into bytes.
120 /// If we're constructing an onion message hop through an intermediate unblinded node, we'll need
121 /// to construct the intermediate hop's control TLVs in their unblinded state to avoid encoding
122 /// them into an intermediate Vec. See [`super::blinded_route::ForwardTlvs`] for more info.
123 Unblinded(ForwardTlvs),
126 /// Receive control TLVs in their blinded and unblinded form.
127 pub(super) enum ReceiveControlTlvs {
128 /// See [`ForwardControlTlvs::Blinded`].
130 /// See [`ForwardControlTlvs::Unblinded`] and [`super::blinded_route::ReceiveTlvs`].
131 Unblinded(ReceiveTlvs),
134 // Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
135 impl Writeable for (Payload, [u8; 32]) {
136 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
138 Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) => {
139 encode_varint_length_prefixed_tlv!(w, {
140 (4, encrypted_bytes, vec_type)
144 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes), reply_path
146 encode_varint_length_prefixed_tlv!(w, {
147 (2, reply_path, option),
148 (4, encrypted_bytes, vec_type)
151 Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
152 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
153 encode_varint_length_prefixed_tlv!(w, {
154 (4, write_adapter, required)
158 control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs), reply_path,
160 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
161 encode_varint_length_prefixed_tlv!(w, {
162 (2, reply_path, option),
163 (4, write_adapter, required)
171 // Uses the provided secret to simultaneously decode and decrypt the control TLVs.
172 impl ReadableArgs<SharedSecret> for Payload {
173 fn read<R: Read>(mut r: &mut R, encrypted_tlvs_ss: SharedSecret) -> Result<Self, DecodeError> {
174 let v: BigSize = Readable::read(r)?;
175 let mut rd = FixedLengthReader::new(r, v.0);
176 let mut reply_path: Option<BlindedRoute> = None;
177 let mut read_adapter: Option<ChaChaPolyReadAdapter<ControlTlvs>> = None;
178 let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes());
179 decode_tlv_stream!(&mut rd, {
180 (2, reply_path, option),
181 (4, read_adapter, (option: LengthReadableArgs, rho))
183 rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
186 None => return Err(DecodeError::InvalidValue),
187 Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(tlvs)}) => {
188 Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
190 Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs)}) => {
191 Ok(Payload::Receive { control_tlvs: ReceiveControlTlvs::Unblinded(tlvs), reply_path })
197 /// When reading a packet off the wire, we don't know a priori whether the packet is to be forwarded
198 /// or received. Thus we read a ControlTlvs rather than reading a ForwardControlTlvs or
199 /// ReceiveControlTlvs directly.
200 pub(super) enum ControlTlvs {
201 /// This onion message is intended to be forwarded.
202 Forward(ForwardTlvs),
203 /// This onion message is intended to be received.
204 Receive(ReceiveTlvs),
207 impl Readable for ControlTlvs {
208 fn read<R: Read>(mut r: &mut R) -> Result<Self, DecodeError> {
209 let mut _padding: Option<Padding> = None;
210 let mut _short_channel_id: Option<u64> = None;
211 let mut next_node_id: Option<PublicKey> = None;
212 let mut path_id: Option<[u8; 32]> = None;
213 let mut next_blinding_override: Option<PublicKey> = None;
214 decode_tlv_stream!(&mut r, {
215 (1, _padding, option),
216 (2, _short_channel_id, option),
217 (4, next_node_id, option),
218 (6, path_id, option),
219 (8, next_blinding_override, option),
222 let valid_fwd_fmt = next_node_id.is_some() && path_id.is_none();
223 let valid_recv_fmt = next_node_id.is_none() && next_blinding_override.is_none();
225 let payload_fmt = if valid_fwd_fmt {
226 ControlTlvs::Forward(ForwardTlvs {
227 next_node_id: next_node_id.unwrap(),
228 next_blinding_override,
230 } else if valid_recv_fmt {
231 ControlTlvs::Receive(ReceiveTlvs {
235 return Err(DecodeError::InvalidValue)
242 /// Reads padding to the end, ignoring what's read.
243 pub(crate) struct Padding {}
244 impl Readable for Padding {
246 fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
248 let mut buf = [0; 8192];
249 if reader.read(&mut buf[..])? == 0 { break; }