_ 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, ForwardTlvs, ReceiveTlvs};
  16 use crate::ln::msgs::DecodeError;
  17 use crate::ln::onion_utils;
  18 use super::messenger::CustomOnionMessageHandler;
  19 use super::offers::OffersMessage;
  20 use crate::util::chacha20poly1305rfc::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
  21 use crate::util::logger::Logger;
  22 use crate::util::ser::{BigSize, FixedLengthReader, LengthRead, LengthReadable, LengthReadableArgs, Readable, ReadableArgs, Writeable, Writer};
  23
  24 use core::cmp;
  25 use crate::io::{self, Read};
  26 use crate::prelude::*;
  27
  28 // Per the spec, an onion message packet's `hop_data` field length should be
  29 // SMALL_PACKET_HOP_DATA_LEN if it fits, else BIG_PACKET_HOP_DATA_LEN if it fits.
  30 pub(super) const SMALL_PACKET_HOP_DATA_LEN: usize = 1300;
  31 pub(super) const BIG_PACKET_HOP_DATA_LEN: usize = 32768;
  32
  33 #[derive(Clone, Debug, PartialEq, Eq)]
  34 pub(crate) struct Packet {
  35         pub(super) version: u8,
  36         pub(super) public_key: PublicKey,
  37         // Unlike the onion packets used for payments, onion message packets can have payloads greater
  38         // than 1300 bytes.
  39         // TODO: if 1300 ends up being the most common size, optimize this to be:
  40         // enum { ThirteenHundred([u8; 1300]), VarLen(Vec<u8>) }
  41         pub(super) hop_data: Vec<u8>,
  42         pub(super) hmac: [u8; 32],
  43 }
  44
  45 impl onion_utils::Packet for Packet {
  46         type Data = Vec<u8>;
  47         fn new(public_key: PublicKey, hop_data: Vec<u8>, hmac: [u8; 32]) -> Packet {
  48                 Self {
  49                         version: 0,
  50                         public_key,
  51                         hop_data,
  52                         hmac,
  53                 }
  54         }
  55 }
  56
  57 impl Writeable for Packet {
  58         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  59                 self.version.write(w)?;
  60                 self.public_key.write(w)?;
  61                 w.write_all(&self.hop_data)?;
  62                 self.hmac.write(w)?;
  63                 Ok(())
  64         }
  65 }
  66
  67 impl LengthReadable for Packet {
  68         fn read<R: LengthRead>(r: &mut R) -> Result<Self, DecodeError> {
  69                 const READ_BUFFER_SIZE: usize = 4096;
  70
  71                 let version = Readable::read(r)?;
  72                 let public_key = Readable::read(r)?;
  73
  74                 let mut hop_data = Vec::new();
  75                 let hop_data_len = r.total_bytes().saturating_sub(66) as usize; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
  76                 let mut read_idx = 0;
  77                 while read_idx < hop_data_len {
  78                         let mut read_buffer = [0; READ_BUFFER_SIZE];
  79                         let read_amt = cmp::min(hop_data_len - read_idx, READ_BUFFER_SIZE);
  80                         r.read_exact(&mut read_buffer[..read_amt])?;
  81                         hop_data.extend_from_slice(&read_buffer[..read_amt]);
  82                         read_idx += read_amt;
  83                 }
  84
  85                 let hmac = Readable::read(r)?;
  86                 Ok(Packet {
  87                         version,
  88                         public_key,
  89                         hop_data,
  90                         hmac,
  91                 })
  92         }
  93 }
  94
  95 /// Onion message payloads contain "control" TLVs and "data" TLVs. Control TLVs are used to route
  96 /// the onion message from hop to hop and for path verification, whereas data TLVs contain the onion
  97 /// message content itself, such as an invoice request.
  98 pub(super) enum Payload<T: CustomOnionMessageContents> {
  99         /// This payload is for an intermediate hop.
 100         Forward(ForwardControlTlvs),
 101         /// This payload is for the final hop.
 102         Receive {
 103                 control_tlvs: ReceiveControlTlvs,
 104                 reply_path: Option<BlindedPath>,
 105                 message: OnionMessageContents<T>,
 106         }
 107 }
 108
 109 #[derive(Debug)]
 110 /// The contents of an onion message. In the context of offers, this would be the invoice, invoice
 111 /// request, or invoice error.
 112 pub enum OnionMessageContents<T: CustomOnionMessageContents> {
 113         /// A message related to BOLT 12 Offers.
 114         Offers(OffersMessage),
 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         /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
 123         pub fn tlv_type(&self) -> u64 {
 124                 match self {
 125                         &OnionMessageContents::Offers(ref msg) => msg.tlv_type(),
 126                         &OnionMessageContents::Custom(ref msg) => msg.tlv_type(),
 127                 }
 128         }
 129 }
 130
 131 /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
 132 impl<T: CustomOnionMessageContents> Writeable for OnionMessageContents<T> {
 133         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 134                 match self {
 135                         OnionMessageContents::Offers(msg) => Ok(msg.write(w)?),
 136                         OnionMessageContents::Custom(msg) => Ok(msg.write(w)?),
 137                 }
 138         }
 139 }
 140
 141 /// The contents of a custom onion message.
 142 pub trait CustomOnionMessageContents: Writeable {
 143         /// Returns the TLV type identifying the message contents. MUST be >= 64.
 144         fn tlv_type(&self) -> u64;
 145 }
 146
 147 /// Forward control TLVs in their blinded and unblinded form.
 148 pub(super) enum ForwardControlTlvs {
 149         /// If we're sending to a blinded path, the node that constructed the blinded path has provided
 150         /// this hop's control TLVs, already encrypted into bytes.
 151         Blinded(Vec<u8>),
 152         /// If we're constructing an onion message hop through an intermediate unblinded node, we'll need
 153         /// to construct the intermediate hop's control TLVs in their unblinded state to avoid encoding
 154         /// them into an intermediate Vec. See [`crate::blinded_path::ForwardTlvs`] for more info.
 155         Unblinded(ForwardTlvs),
 156 }
 157
 158 /// Receive control TLVs in their blinded and unblinded form.
 159 pub(super) enum ReceiveControlTlvs {
 160         /// See [`ForwardControlTlvs::Blinded`].
 161         Blinded(Vec<u8>),
 162         /// See [`ForwardControlTlvs::Unblinded`] and [`crate::blinded_path::ReceiveTlvs`].
 163         Unblinded(ReceiveTlvs),
 164 }
 165
 166 // Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
 167 impl<T: CustomOnionMessageContents> Writeable for (Payload<T>, [u8; 32]) {
 168         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 169                 match &self.0 {
 170                         Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) => {
 171                                 _encode_varint_length_prefixed_tlv!(w, {
 172                                         (4, *encrypted_bytes, vec_type)
 173                                 })
 174                         },
 175                         Payload::Receive {
 176                                 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes), reply_path, message,
 177                         } => {
 178                                 _encode_varint_length_prefixed_tlv!(w, {
 179                                         (2, reply_path, option),
 180                                         (4, *encrypted_bytes, vec_type),
 181                                         (message.tlv_type(), message, required)
 182                                 })
 183                         },
 184                         Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
 185                                 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
 186                                 _encode_varint_length_prefixed_tlv!(w, {
 187                                         (4, write_adapter, required)
 188                                 })
 189                         },
 190                         Payload::Receive {
 191                                 control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs), reply_path, message,
 192                         } => {
 193                                 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
 194                                 _encode_varint_length_prefixed_tlv!(w, {
 195                                         (2, reply_path, option),
 196                                         (4, write_adapter, required),
 197                                         (message.tlv_type(), message, required)
 198                                 })
 199                         },
 200                 }
 201                 Ok(())
 202         }
 203 }
 204
 205 // Uses the provided secret to simultaneously decode and decrypt the control TLVs and data TLV.
 206 impl<H: CustomOnionMessageHandler, L: Logger>
 207 ReadableArgs<(SharedSecret, &H, &L)> for Payload<<H as CustomOnionMessageHandler>::CustomMessage> {
 208         fn read<R: Read>(r: &mut R, args: (SharedSecret, &H, &L)) -> Result<Self, DecodeError> {
 209                 let (encrypted_tlvs_ss, handler, logger) = args;
 210
 211                 let v: BigSize = Readable::read(r)?;
 212                 let mut rd = FixedLengthReader::new(r, v.0);
 213                 let mut reply_path: Option<BlindedPath> = None;
 214                 let mut read_adapter: Option<ChaChaPolyReadAdapter<ControlTlvs>> = None;
 215                 let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes());
 216                 let mut message_type: Option<u64> = None;
 217                 let mut message = None;
 218                 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
 219                         (2, reply_path, option),
 220                         (4, read_adapter, (option: LengthReadableArgs, rho)),
 221                 }, |msg_type, msg_reader| {
 222                         if msg_type < 64 { return Ok(false) }
 223                         // Don't allow reading more than one data TLV from an onion message.
 224                         if message_type.is_some() { return Err(DecodeError::InvalidValue) }
 225
 226                         message_type = Some(msg_type);
 227                         match msg_type {
 228                                 tlv_type if OffersMessage::is_known_type(tlv_type) => {
 229                                         let msg = OffersMessage::read(msg_reader, (tlv_type, logger))?;
 230                                         message = Some(OnionMessageContents::Offers(msg));
 231                                         Ok(true)
 232                                 },
 233                                 _ => match handler.read_custom_message(msg_type, msg_reader)? {
 234                                         Some(msg) => {
 235                                                 message = Some(OnionMessageContents::Custom(msg));
 236                                                 Ok(true)
 237                                         },
 238                                         None => Ok(false),
 239                                 },
 240                         }
 241                 });
 242                 rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
 243
 244                 match read_adapter {
 245                         None => return Err(DecodeError::InvalidValue),
 246                         Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(tlvs)}) => {
 247                                 if message_type.is_some() {
 248                                         return Err(DecodeError::InvalidValue)
 249                                 }
 250                                 Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
 251                         },
 252                         Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs)}) => {
 253                                 Ok(Payload::Receive {
 254                                         control_tlvs: ReceiveControlTlvs::Unblinded(tlvs),
 255                                         reply_path,
 256                                         message: message.ok_or(DecodeError::InvalidValue)?,
 257                                 })
 258                         },
 259                 }
 260         }
 261 }
 262
 263 /// When reading a packet off the wire, we don't know a priori whether the packet is to be forwarded
 264 /// or received. Thus we read a ControlTlvs rather than reading a ForwardControlTlvs or
 265 /// ReceiveControlTlvs directly.
 266 pub(crate) enum ControlTlvs {
 267         /// This onion message is intended to be forwarded.
 268         Forward(ForwardTlvs),
 269         /// This onion message is intended to be received.
 270         Receive(ReceiveTlvs),
 271 }
 272
 273 impl Readable for ControlTlvs {
 274         fn read<R: Read>(mut r: &mut R) -> Result<Self, DecodeError> {
 275                 let mut _padding: Option<Padding> = None;
 276                 let mut _short_channel_id: Option<u64> = None;
 277                 let mut next_node_id: Option<PublicKey> = None;
 278                 let mut path_id: Option<[u8; 32]> = None;
 279                 let mut next_blinding_override: Option<PublicKey> = None;
 280                 decode_tlv_stream!(&mut r, {
 281                         (1, _padding, option),
 282                         (2, _short_channel_id, option),
 283                         (4, next_node_id, option),
 284                         (6, path_id, option),
 285                         (8, next_blinding_override, option),
 286                 });
 287
 288                 let valid_fwd_fmt  = next_node_id.is_some() && path_id.is_none();
 289                 let valid_recv_fmt = next_node_id.is_none() && next_blinding_override.is_none();
 290
 291                 let payload_fmt = if valid_fwd_fmt {
 292                         ControlTlvs::Forward(ForwardTlvs {
 293                                 next_node_id: next_node_id.unwrap(),
 294                                 next_blinding_override,
 295                         })
 296                 } else if valid_recv_fmt {
 297                         ControlTlvs::Receive(ReceiveTlvs {
 298                                 path_id,
 299                         })
 300                 } else {
 301                         return Err(DecodeError::InvalidValue)
 302                 };
 303
 304                 Ok(payload_fmt)
 305         }
 306 }
 307
 308 /// Reads padding to the end, ignoring what's read.
 309 pub(crate) struct Padding {}
 310 impl Readable for Padding {
 311         #[inline]
 312         fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
 313                 loop {
 314                         let mut buf = [0; 8192];
 315                         if reader.read(&mut buf[..])? == 0 { break; }
 316                 }
 317                 Ok(Self {})
 318         }
 319 }