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::{ForwardTlvs, ReceiveTlvs};
18 use util::chacha20poly1305rfc::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
19 use util::ser::{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() as usize - 66; // 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,
102 // 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 Payload::Receive { control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes)} => {
140 encode_varint_length_prefixed_tlv!(w, {
141 (4, encrypted_bytes, vec_type)
144 Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
145 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
146 encode_varint_length_prefixed_tlv!(w, {
147 (4, write_adapter, required)
150 Payload::Receive { control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs)} => {
151 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
152 encode_varint_length_prefixed_tlv!(w, {
153 (4, write_adapter, required)
161 // Uses the provided secret to simultaneously decode and decrypt the control TLVs.
162 impl ReadableArgs<SharedSecret> for Payload {
163 fn read<R: Read>(mut r: &mut R, encrypted_tlvs_ss: SharedSecret) -> Result<Self, DecodeError> {
164 use bitcoin::consensus::encode::{Decodable, Error, VarInt};
165 let v: VarInt = Decodable::consensus_decode(&mut r)
166 .map_err(|e| match e {
167 Error::Io(ioe) => DecodeError::from(ioe),
168 _ => DecodeError::InvalidValue
171 let mut rd = FixedLengthReader::new(r, v.0);
172 // TODO: support reply paths
173 let mut _reply_path_bytes: Option<Vec<u8>> = Some(Vec::new());
174 let mut read_adapter: Option<ChaChaPolyReadAdapter<ControlTlvs>> = None;
175 let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes());
176 decode_tlv_stream!(&mut rd, {
177 (2, _reply_path_bytes, vec_type),
178 (4, read_adapter, (option: LengthReadableArgs, rho))
180 rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
183 None => return Err(DecodeError::InvalidValue),
184 Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(tlvs)}) => {
185 Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
187 Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs)}) => {
188 Ok(Payload::Receive { control_tlvs: ReceiveControlTlvs::Unblinded(tlvs)})
194 /// When reading a packet off the wire, we don't know a priori whether the packet is to be forwarded
195 /// or received. Thus we read a ControlTlvs rather than reading a ForwardControlTlvs or
196 /// ReceiveControlTlvs directly.
197 pub(super) enum ControlTlvs {
198 /// This onion message is intended to be forwarded.
199 Forward(ForwardTlvs),
200 /// This onion message is intended to be received.
201 Receive(ReceiveTlvs),
204 impl Readable for ControlTlvs {
205 fn read<R: Read>(mut r: &mut R) -> Result<Self, DecodeError> {
206 let mut _padding: Option<Padding> = None;
207 let mut _short_channel_id: Option<u64> = None;
208 let mut next_node_id: Option<PublicKey> = None;
209 let mut path_id: Option<[u8; 32]> = None;
210 let mut next_blinding_override: Option<PublicKey> = None;
211 decode_tlv_stream!(&mut r, {
212 (1, _padding, option),
213 (2, _short_channel_id, option),
214 (4, next_node_id, option),
215 (6, path_id, option),
216 (8, next_blinding_override, option),
219 let valid_fwd_fmt = next_node_id.is_some() && path_id.is_none();
220 let valid_recv_fmt = next_node_id.is_none() && next_blinding_override.is_none();
222 let payload_fmt = if valid_fwd_fmt {
223 ControlTlvs::Forward(ForwardTlvs {
224 next_node_id: next_node_id.unwrap(),
225 next_blinding_override,
227 } else if valid_recv_fmt {
228 ControlTlvs::Receive(ReceiveTlvs {
232 return Err(DecodeError::InvalidValue)
239 /// Reads padding to the end, ignoring what's read.
240 pub(crate) struct Padding {}
241 impl Readable for Padding {
243 fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
245 let mut buf = [0; 8192];
246 if reader.read(&mut buf[..])? == 0 { break; }