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Merge pull request #2102 from douglaz/node_info_addresses
[rust-lightning] / lightning / src / onion_message / packet.rs
1 // This file is Copyright its original authors, visible in version control
2 // history.
3 //
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
8 // licenses.
9
10 //! Structs and enums useful for constructing and reading an onion message packet.
11
12 use bitcoin::secp256k1::PublicKey;
13 use bitcoin::secp256k1::ecdh::SharedSecret;
14
15 use crate::ln::msgs::DecodeError;
16 use crate::ln::onion_utils;
17 use super::blinded_path::{BlindedPath, ForwardTlvs, ReceiveTlvs};
18 use super::messenger::CustomOnionMessageHandler;
19 use crate::util::chacha20poly1305rfc::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
20 use crate::util::ser::{BigSize, FixedLengthReader, LengthRead, LengthReadable, LengthReadableArgs, Readable, ReadableArgs, Writeable, Writer};
21
22 use core::cmp;
23 use crate::io::{self, Read};
24 use crate::prelude::*;
25
26 // Per the spec, an onion message packet's `hop_data` field length should be
27 // SMALL_PACKET_HOP_DATA_LEN if it fits, else BIG_PACKET_HOP_DATA_LEN if it fits.
28 pub(super) const SMALL_PACKET_HOP_DATA_LEN: usize = 1300;
29 pub(super) const BIG_PACKET_HOP_DATA_LEN: usize = 32768;
30
31 #[derive(Clone, Debug, PartialEq, Eq)]
32 pub(crate) struct Packet {
33         pub(super) version: u8,
34         pub(super) public_key: PublicKey,
35         // Unlike the onion packets used for payments, onion message packets can have payloads greater
36         // than 1300 bytes.
37         // TODO: if 1300 ends up being the most common size, optimize this to be:
38         // enum { ThirteenHundred([u8; 1300]), VarLen(Vec<u8>) }
39         pub(super) hop_data: Vec<u8>,
40         pub(super) hmac: [u8; 32],
41 }
42
43 impl onion_utils::Packet for Packet {
44         type Data = Vec<u8>;
45         fn new(public_key: PublicKey, hop_data: Vec<u8>, hmac: [u8; 32]) -> Packet {
46                 Self {
47                         version: 0,
48                         public_key,
49                         hop_data,
50                         hmac,
51                 }
52         }
53 }
54
55 impl Writeable for Packet {
56         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
57                 self.version.write(w)?;
58                 self.public_key.write(w)?;
59                 w.write_all(&self.hop_data)?;
60                 self.hmac.write(w)?;
61                 Ok(())
62         }
63 }
64
65 impl LengthReadable for Packet {
66         fn read<R: LengthRead>(r: &mut R) -> Result<Self, DecodeError> {
67                 const READ_BUFFER_SIZE: usize = 4096;
68
69                 let version = Readable::read(r)?;
70                 let public_key = Readable::read(r)?;
71
72                 let mut hop_data = Vec::new();
73                 let hop_data_len = r.total_bytes().saturating_sub(66) as usize; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
74                 let mut read_idx = 0;
75                 while read_idx < hop_data_len {
76                         let mut read_buffer = [0; READ_BUFFER_SIZE];
77                         let read_amt = cmp::min(hop_data_len - read_idx, READ_BUFFER_SIZE);
78                         r.read_exact(&mut read_buffer[..read_amt])?;
79                         hop_data.extend_from_slice(&read_buffer[..read_amt]);
80                         read_idx += read_amt;
81                 }
82
83                 let hmac = Readable::read(r)?;
84                 Ok(Packet {
85                         version,
86                         public_key,
87                         hop_data,
88                         hmac,
89                 })
90         }
91 }
92
93 /// Onion message payloads contain "control" TLVs and "data" TLVs. Control TLVs are used to route
94 /// the onion message from hop to hop and for path verification, whereas data TLVs contain the onion
95 /// message content itself, such as an invoice request.
96 pub(super) enum Payload<T: CustomOnionMessageContents> {
97         /// This payload is for an intermediate hop.
98         Forward(ForwardControlTlvs),
99         /// This payload is for the final hop.
100         Receive {
101                 control_tlvs: ReceiveControlTlvs,
102                 reply_path: Option<BlindedPath>,
103                 message: OnionMessageContents<T>,
104         }
105 }
106
107 #[derive(Debug)]
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: CustomOnionMessageContents> {
111         // Coming soon:
112         // Invoice,
113         // InvoiceRequest,
114         // InvoiceError,
115         /// A custom onion message specified by the user.
116         Custom(T),
117 }
118
119 impl<T: CustomOnionMessageContents> OnionMessageContents<T> {
120         /// Returns the type that was used to decode the message payload.
121         ///
122         /// (C-not exported) as methods on non-cloneable enums are not currently exportable
123         pub fn tlv_type(&self) -> u64 {
124                 match self {
125                         &OnionMessageContents::Custom(ref msg) => msg.tlv_type(),
126                 }
127         }
128 }
129
130 /// (C-not exported) as methods on non-cloneable enums are not currently exportable
131 impl<T: CustomOnionMessageContents> Writeable for OnionMessageContents<T> {
132         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
133                 match self {
134                         OnionMessageContents::Custom(msg) => Ok(msg.write(w)?),
135                 }
136         }
137 }
138
139 /// The contents of a custom onion message.
140 pub trait CustomOnionMessageContents: Writeable {
141         /// Returns the TLV type identifying the message contents. MUST be >= 64.
142         fn tlv_type(&self) -> u64;
143 }
144
145 /// Forward control TLVs in their blinded and unblinded form.
146 pub(super) enum ForwardControlTlvs {
147         /// If we're sending to a blinded path, the node that constructed the blinded path has provided
148         /// this hop's control TLVs, already encrypted into bytes.
149         Blinded(Vec<u8>),
150         /// If we're constructing an onion message hop through an intermediate unblinded node, we'll need
151         /// to construct the intermediate hop's control TLVs in their unblinded state to avoid encoding
152         /// them into an intermediate Vec. See [`super::blinded_path::ForwardTlvs`] for more info.
153         Unblinded(ForwardTlvs),
154 }
155
156 /// Receive control TLVs in their blinded and unblinded form.
157 pub(super) enum ReceiveControlTlvs {
158         /// See [`ForwardControlTlvs::Blinded`].
159         Blinded(Vec<u8>),
160         /// See [`ForwardControlTlvs::Unblinded`] and [`super::blinded_path::ReceiveTlvs`].
161         Unblinded(ReceiveTlvs),
162 }
163
164 // Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
165 impl<T: CustomOnionMessageContents> Writeable for (Payload<T>, [u8; 32]) {
166         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
167                 match &self.0 {
168                         Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) => {
169                                 _encode_varint_length_prefixed_tlv!(w, {
170                                         (4, *encrypted_bytes, vec_type)
171                                 })
172                         },
173                         Payload::Receive {
174                                 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes), reply_path, message,
175                         } => {
176                                 _encode_varint_length_prefixed_tlv!(w, {
177                                         (2, reply_path, option),
178                                         (4, *encrypted_bytes, vec_type),
179                                         (message.tlv_type(), message, required)
180                                 })
181                         },
182                         Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
183                                 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
184                                 _encode_varint_length_prefixed_tlv!(w, {
185                                         (4, write_adapter, required)
186                                 })
187                         },
188                         Payload::Receive {
189                                 control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs), reply_path, message,
190                         } => {
191                                 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
192                                 _encode_varint_length_prefixed_tlv!(w, {
193                                         (2, reply_path, option),
194                                         (4, write_adapter, required),
195                                         (message.tlv_type(), message, required)
196                                 })
197                         },
198                 }
199                 Ok(())
200         }
201 }
202
203 // Uses the provided secret to simultaneously decode and decrypt the control TLVs and data TLV.
204 impl<H: CustomOnionMessageHandler> ReadableArgs<(SharedSecret, &H)> for Payload<<H as CustomOnionMessageHandler>::CustomMessage> {
205         fn read<R: Read>(r: &mut R, args: (SharedSecret, &H)) -> Result<Self, DecodeError> {
206                 let (encrypted_tlvs_ss, handler) = args;
207
208                 let v: BigSize = Readable::read(r)?;
209                 let mut rd = FixedLengthReader::new(r, v.0);
210                 let mut reply_path: Option<BlindedPath> = None;
211                 let mut read_adapter: Option<ChaChaPolyReadAdapter<ControlTlvs>> = None;
212                 let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes());
213                 let mut message_type: Option<u64> = None;
214                 let mut message = None;
215                 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
216                         (2, reply_path, option),
217                         (4, read_adapter, (option: LengthReadableArgs, rho)),
218                 }, |msg_type, msg_reader| {
219                         if msg_type < 64 { return Ok(false) }
220                         // Don't allow reading more than one data TLV from an onion message.
221                         if message_type.is_some() { return Err(DecodeError::InvalidValue) }
222
223                         message_type = Some(msg_type);
224                         match handler.read_custom_message(msg_type, msg_reader) {
225                                 Ok(Some(msg)) => {
226                                         message = Some(msg);
227                                         Ok(true)
228                                 },
229                                 Ok(None) => Ok(false),
230                                 Err(e) => Err(e),
231                         }
232                 });
233                 rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
234
235                 match read_adapter {
236                         None => return Err(DecodeError::InvalidValue),
237                         Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(tlvs)}) => {
238                                 if message_type.is_some() {
239                                         return Err(DecodeError::InvalidValue)
240                                 }
241                                 Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
242                         },
243                         Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs)}) => {
244                                 if message.is_none() { return Err(DecodeError::InvalidValue) }
245                                 Ok(Payload::Receive {
246                                         control_tlvs: ReceiveControlTlvs::Unblinded(tlvs),
247                                         reply_path,
248                                         message: OnionMessageContents::Custom(message.unwrap()),
249                                 })
250                         }
251                 }
252         }
253 }
254
255 /// When reading a packet off the wire, we don't know a priori whether the packet is to be forwarded
256 /// or received. Thus we read a ControlTlvs rather than reading a ForwardControlTlvs or
257 /// ReceiveControlTlvs directly.
258 pub(super) enum ControlTlvs {
259         /// This onion message is intended to be forwarded.
260         Forward(ForwardTlvs),
261         /// This onion message is intended to be received.
262         Receive(ReceiveTlvs),
263 }
264
265 impl Readable for ControlTlvs {
266         fn read<R: Read>(mut r: &mut R) -> Result<Self, DecodeError> {
267                 let mut _padding: Option<Padding> = None;
268                 let mut _short_channel_id: Option<u64> = None;
269                 let mut next_node_id: Option<PublicKey> = None;
270                 let mut path_id: Option<[u8; 32]> = None;
271                 let mut next_blinding_override: Option<PublicKey> = None;
272                 decode_tlv_stream!(&mut r, {
273                         (1, _padding, option),
274                         (2, _short_channel_id, option),
275                         (4, next_node_id, option),
276                         (6, path_id, option),
277                         (8, next_blinding_override, option),
278                 });
279
280                 let valid_fwd_fmt  = next_node_id.is_some() && path_id.is_none();
281                 let valid_recv_fmt = next_node_id.is_none() && next_blinding_override.is_none();
282
283                 let payload_fmt = if valid_fwd_fmt {
284                         ControlTlvs::Forward(ForwardTlvs {
285                                 next_node_id: next_node_id.unwrap(),
286                                 next_blinding_override,
287                         })
288                 } else if valid_recv_fmt {
289                         ControlTlvs::Receive(ReceiveTlvs {
290                                 path_id,
291                         })
292                 } else {
293                         return Err(DecodeError::InvalidValue)
294                 };
295
296                 Ok(payload_fmt)
297         }
298 }
299
300 /// Reads padding to the end, ignoring what's read.
301 pub(crate) struct Padding {}
302 impl Readable for Padding {
303         #[inline]
304         fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
305                 loop {
306                         let mut buf = [0; 8192];
307                         if reader.read(&mut buf[..])? == 0 { break; }
308                 }
309                 Ok(Self {})
310         }
311 }