_ Git - rust-lightning/blob - 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::blinded_path::{BlindedPath, NextMessageHop};
  16 use crate::blinded_path::message::{ForwardTlvs, ReceiveTlvs};
  17 use crate::blinded_path::utils::Padding;
  18 use crate::ln::msgs::DecodeError;
  19 use crate::ln::onion_utils;
  20 #[cfg(async_payments)]
  21 use super::async_payments::AsyncPaymentsMessage;
  22 use super::messenger::CustomOnionMessageHandler;
  23 use super::offers::OffersMessage;
  24 use crate::crypto::streams::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
  25 use crate::util::logger::Logger;
  26 use crate::util::ser::{BigSize, FixedLengthReader, LengthRead, LengthReadable, LengthReadableArgs, Readable, ReadableArgs, Writeable, Writer};
  27
  28 use core::cmp;
  29 use core::fmt;
  30 use crate::io::{self, Read};
  31 use crate::prelude::*;
  32
  33 // Per the spec, an onion message packet's `hop_data` field length should be
  34 // SMALL_PACKET_HOP_DATA_LEN if it fits, else BIG_PACKET_HOP_DATA_LEN if it fits.
  35 pub(super) const SMALL_PACKET_HOP_DATA_LEN: usize = 1300;
  36 pub(super) const BIG_PACKET_HOP_DATA_LEN: usize = 32768;
  37
  38 /// Packet of hop data for next peer
  39 #[derive(Clone, Hash, PartialEq, Eq)]
  40 pub struct Packet {
  41         /// Bolt 04 version number
  42         pub version: u8,
  43         /// A random sepc256k1 point, used to build the ECDH shared secret to decrypt hop_data
  44         pub public_key: PublicKey,
  45         /// Encrypted payload for the next hop
  46         //
  47         // Unlike the onion packets used for payments, onion message packets can have payloads greater
  48         // than 1300 bytes.
  49         // TODO: if 1300 ends up being the most common size, optimize this to be:
  50         // enum { ThirteenHundred([u8; 1300]), VarLen(Vec<u8>) }
  51         pub hop_data: Vec<u8>,
  52         /// HMAC to verify the integrity of hop_data
  53         pub hmac: [u8; 32],
  54 }
  55
  56 impl onion_utils::Packet for Packet {
  57         type Data = Vec<u8>;
  58         fn new(public_key: PublicKey, hop_data: Vec<u8>, hmac: [u8; 32]) -> Packet {
  59                 Self {
  60                         version: 0,
  61                         public_key,
  62                         hop_data,
  63                         hmac,
  64                 }
  65         }
  66 }
  67
  68 impl fmt::Debug for Packet {
  69         fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  70                 f.write_fmt(format_args!("Onion message packet version {} with hmac {:?}", self.version, &self.hmac[..]))
  71         }
  72 }
  73
  74 impl Writeable for Packet {
  75         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  76                 self.version.write(w)?;
  77                 self.public_key.write(w)?;
  78                 w.write_all(&self.hop_data)?;
  79                 self.hmac.write(w)?;
  80                 Ok(())
  81         }
  82 }
  83
  84 impl LengthReadable for Packet {
  85         fn read<R: LengthRead>(r: &mut R) -> Result<Self, DecodeError> {
  86                 const READ_BUFFER_SIZE: usize = 4096;
  87
  88                 let version = Readable::read(r)?;
  89                 let public_key = Readable::read(r)?;
  90
  91                 let mut hop_data = Vec::new();
  92                 let hop_data_len = r.total_bytes().saturating_sub(66) as usize; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
  93                 let mut read_idx = 0;
  94                 while read_idx < hop_data_len {
  95                         let mut read_buffer = [0; READ_BUFFER_SIZE];
  96                         let read_amt = cmp::min(hop_data_len - read_idx, READ_BUFFER_SIZE);
  97                         r.read_exact(&mut read_buffer[..read_amt])?;
  98                         hop_data.extend_from_slice(&read_buffer[..read_amt]);
  99                         read_idx += read_amt;
 100                 }
 101
 102                 let hmac = Readable::read(r)?;
 103                 Ok(Packet {
 104                         version,
 105                         public_key,
 106                         hop_data,
 107                         hmac,
 108                 })
 109         }
 110 }
 111
 112 /// Onion message payloads contain "control" TLVs and "data" TLVs. Control TLVs are used to route
 113 /// the onion message from hop to hop and for path verification, whereas data TLVs contain the onion
 114 /// message content itself, such as an invoice request.
 115 pub(super) enum Payload<T: OnionMessageContents> {
 116         /// This payload is for an intermediate hop.
 117         Forward(ForwardControlTlvs),
 118         /// This payload is for the final hop.
 119         Receive {
 120                 control_tlvs: ReceiveControlTlvs,
 121                 reply_path: Option<BlindedPath>,
 122                 message: T,
 123         }
 124 }
 125
 126 /// The contents of an [`OnionMessage`] as read from the wire.
 127 ///
 128 /// [`OnionMessage`]: crate::ln::msgs::OnionMessage
 129 #[derive(Clone, Debug)]
 130 pub enum ParsedOnionMessageContents<T: OnionMessageContents> {
 131         /// A message related to BOLT 12 Offers.
 132         Offers(OffersMessage),
 133         /// A message related to async payments.
 134         #[cfg(async_payments)]
 135         AsyncPayments(AsyncPaymentsMessage),
 136         /// A custom onion message specified by the user.
 137         Custom(T),
 138 }
 139
 140 impl<T: OnionMessageContents> OnionMessageContents for ParsedOnionMessageContents<T> {
 141         /// Returns the type that was used to decode the message payload.
 142         ///
 143         /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
 144         fn tlv_type(&self) -> u64 {
 145                 match self {
 146                         &ParsedOnionMessageContents::Offers(ref msg) => msg.tlv_type(),
 147                         #[cfg(async_payments)]
 148                         &ParsedOnionMessageContents::AsyncPayments(ref msg) => msg.tlv_type(),
 149                         &ParsedOnionMessageContents::Custom(ref msg) => msg.tlv_type(),
 150                 }
 151         }
 152         fn msg_type(&self) -> &'static str {
 153                 match self {
 154                         ParsedOnionMessageContents::Offers(ref msg) => msg.msg_type(),
 155                         #[cfg(async_payments)]
 156                         ParsedOnionMessageContents::AsyncPayments(ref msg) => msg.msg_type(),
 157                         ParsedOnionMessageContents::Custom(ref msg) => msg.msg_type(),
 158                 }
 159         }
 160 }
 161
 162 impl<T: OnionMessageContents> Writeable for ParsedOnionMessageContents<T> {
 163         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 164                 match self {
 165                         ParsedOnionMessageContents::Offers(msg) => Ok(msg.write(w)?),
 166                         #[cfg(async_payments)]
 167                         ParsedOnionMessageContents::AsyncPayments(msg) => Ok(msg.write(w)?),
 168                         ParsedOnionMessageContents::Custom(msg) => Ok(msg.write(w)?),
 169                 }
 170         }
 171 }
 172
 173 /// The contents of an onion message.
 174 pub trait OnionMessageContents: Writeable + core::fmt::Debug {
 175         /// Returns the TLV type identifying the message contents. MUST be >= 64.
 176         fn tlv_type(&self) -> u64;
 177
 178         /// Returns the message type
 179         fn msg_type(&self) -> &'static str;
 180 }
 181
 182 /// Forward control TLVs in their blinded and unblinded form.
 183 pub(super) enum ForwardControlTlvs {
 184         /// If we're sending to a blinded path, the node that constructed the blinded path has provided
 185         /// this hop's control TLVs, already encrypted into bytes.
 186         Blinded(Vec<u8>),
 187         /// If we're constructing an onion message hop through an intermediate unblinded node, we'll need
 188         /// to construct the intermediate hop's control TLVs in their unblinded state to avoid encoding
 189         /// them into an intermediate Vec. See [`crate::blinded_path::message::ForwardTlvs`] for more
 190         /// info.
 191         Unblinded(ForwardTlvs),
 192 }
 193
 194 /// Receive control TLVs in their blinded and unblinded form.
 195 pub(super) enum ReceiveControlTlvs {
 196         /// See [`ForwardControlTlvs::Blinded`].
 197         Blinded(Vec<u8>),
 198         /// See [`ForwardControlTlvs::Unblinded`] and [`crate::blinded_path::message::ReceiveTlvs`].
 199         Unblinded(ReceiveTlvs),
 200 }
 201
 202 // Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
 203 impl<T: OnionMessageContents> Writeable for (Payload<T>, [u8; 32]) {
 204         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 205                 match &self.0 {
 206                         Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) => {
 207                                 _encode_varint_length_prefixed_tlv!(w, {
 208                                         (4, *encrypted_bytes, required_vec)
 209                                 })
 210                         },
 211                         Payload::Receive {
 212                                 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes), reply_path, message,
 213                         } => {
 214                                 _encode_varint_length_prefixed_tlv!(w, {
 215                                         (2, reply_path, option),
 216                                         (4, *encrypted_bytes, required_vec),
 217                                         (message.tlv_type(), message, required)
 218                                 })
 219                         },
 220                         Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
 221                                 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
 222                                 _encode_varint_length_prefixed_tlv!(w, {
 223                                         (4, write_adapter, required)
 224                                 })
 225                         },
 226                         Payload::Receive {
 227                                 control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs), reply_path, message,
 228                         } => {
 229                                 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
 230                                 _encode_varint_length_prefixed_tlv!(w, {
 231                                         (2, reply_path, option),
 232                                         (4, write_adapter, required),
 233                                         (message.tlv_type(), message, required)
 234                                 })
 235                         },
 236                 }
 237                 Ok(())
 238         }
 239 }
 240
 241 // Uses the provided secret to simultaneously decode and decrypt the control TLVs and data TLV.
 242 impl<H: CustomOnionMessageHandler + ?Sized, L: Logger + ?Sized> ReadableArgs<(SharedSecret, &H, &L)>
 243 for Payload<ParsedOnionMessageContents<<H as CustomOnionMessageHandler>::CustomMessage>> {
 244         fn read<R: Read>(r: &mut R, args: (SharedSecret, &H, &L)) -> Result<Self, DecodeError> {
 245                 let (encrypted_tlvs_ss, handler, logger) = args;
 246
 247                 let v: BigSize = Readable::read(r)?;
 248                 let mut rd = FixedLengthReader::new(r, v.0);
 249                 let mut reply_path: Option<BlindedPath> = None;
 250                 let mut read_adapter: Option<ChaChaPolyReadAdapter<ControlTlvs>> = None;
 251                 let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes());
 252                 let mut message_type: Option<u64> = None;
 253                 let mut message = None;
 254                 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
 255                         (2, reply_path, option),
 256                         (4, read_adapter, (option: LengthReadableArgs, rho)),
 257                 }, |msg_type, msg_reader| {
 258                         if msg_type < 64 { return Ok(false) }
 259                         // Don't allow reading more than one data TLV from an onion message.
 260                         if message_type.is_some() { return Err(DecodeError::InvalidValue) }
 261
 262                         message_type = Some(msg_type);
 263                         match msg_type {
 264                                 tlv_type if OffersMessage::is_known_type(tlv_type) => {
 265                                         let msg = OffersMessage::read(msg_reader, (tlv_type, logger))?;
 266                                         message = Some(ParsedOnionMessageContents::Offers(msg));
 267                                         Ok(true)
 268                                 },
 269                                 #[cfg(async_payments)]
 270                                 tlv_type if AsyncPaymentsMessage::is_known_type(tlv_type) => {
 271                                         let msg = AsyncPaymentsMessage::read(msg_reader, tlv_type)?;
 272                                         message = Some(ParsedOnionMessageContents::AsyncPayments(msg));
 273                                         Ok(true)
 274                                 },
 275                                 _ => match handler.read_custom_message(msg_type, msg_reader)? {
 276                                         Some(msg) => {
 277                                                 message = Some(ParsedOnionMessageContents::Custom(msg));
 278                                                 Ok(true)
 279                                         },
 280                                         None => Ok(false),
 281                                 },
 282                         }
 283                 });
 284                 rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
 285
 286                 match read_adapter {
 287                         None => return Err(DecodeError::InvalidValue),
 288                         Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(tlvs)}) => {
 289                                 if message_type.is_some() {
 290                                         return Err(DecodeError::InvalidValue)
 291                                 }
 292                                 Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
 293                         },
 294                         Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs)}) => {
 295                                 Ok(Payload::Receive {
 296                                         control_tlvs: ReceiveControlTlvs::Unblinded(tlvs),
 297                                         reply_path,
 298                                         message: message.ok_or(DecodeError::InvalidValue)?,
 299                                 })
 300                         },
 301                 }
 302         }
 303 }
 304
 305 /// When reading a packet off the wire, we don't know a priori whether the packet is to be forwarded
 306 /// or received. Thus we read a `ControlTlvs` rather than reading a [`ForwardTlvs`] or
 307 /// [`ReceiveTlvs`] directly. Also useful on the encoding side to keep forward and receive TLVs in
 308 /// the same iterator.
 309 pub(crate) enum ControlTlvs {
 310         /// This onion message is intended to be forwarded.
 311         Forward(ForwardTlvs),
 312         /// This onion message is intended to be received.
 313         Receive(ReceiveTlvs),
 314 }
 315
 316 impl Readable for ControlTlvs {
 317         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 318                 _init_and_read_tlv_stream!(r, {
 319                         (1, _padding, option),
 320                         (2, short_channel_id, option),
 321                         (4, next_node_id, option),
 322                         (6, path_id, option),
 323                         (8, next_blinding_override, option),
 324                 });
 325                 let _padding: Option<Padding> = _padding;
 326
 327                 let next_hop = match (short_channel_id, next_node_id) {
 328                         (Some(_), Some(_)) => return Err(DecodeError::InvalidValue),
 329                         (Some(scid), None) => Some(NextMessageHop::ShortChannelId(scid)),
 330                         (None, Some(pubkey)) => Some(NextMessageHop::NodeId(pubkey)),
 331                         (None, None) => None,
 332                 };
 333
 334                 let valid_fwd_fmt = next_hop.is_some() && path_id.is_none();
 335                 let valid_recv_fmt = next_hop.is_none() && next_blinding_override.is_none();
 336
 337                 let payload_fmt = if valid_fwd_fmt {
 338                         ControlTlvs::Forward(ForwardTlvs {
 339                                 next_hop: next_hop.unwrap(),
 340                                 next_blinding_override,
 341                         })
 342                 } else if valid_recv_fmt {
 343                         ControlTlvs::Receive(ReceiveTlvs {
 344                                 path_id,
 345                         })
 346                 } else {
 347                         return Err(DecodeError::InvalidValue)
 348                 };
 349
 350                 Ok(payload_fmt)
 351         }
 352 }
 353
 354 impl Writeable for ControlTlvs {
 355         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 356                 match self {
 357                         Self::Forward(tlvs) => tlvs.write(w),
 358                         Self::Receive(tlvs) => tlvs.write(w),
 359                 }
 360         }
 361 }