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