_ 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;
  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::messenger::CustomOnionMessageHandler;
  21 use super::offers::OffersMessage;
  22 use crate::util::chacha20poly1305rfc::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
  23 use crate::util::logger::Logger;
  24 use crate::util::ser::{BigSize, FixedLengthReader, LengthRead, LengthReadable, LengthReadableArgs, Readable, ReadableArgs, Writeable, Writer};
  25
  26 use core::cmp;
  27 use crate::io::{self, Read};
  28 use crate::prelude::*;
  29
  30 // Per the spec, an onion message packet's `hop_data` field length should be
  31 // SMALL_PACKET_HOP_DATA_LEN if it fits, else BIG_PACKET_HOP_DATA_LEN if it fits.
  32 pub(super) const SMALL_PACKET_HOP_DATA_LEN: usize = 1300;
  33 pub(super) const BIG_PACKET_HOP_DATA_LEN: usize = 32768;
  34
  35 #[derive(Clone, Debug, PartialEq, Eq)]
  36 pub(crate) struct Packet {
  37         pub(super) version: u8,
  38         pub(super) public_key: PublicKey,
  39         // Unlike the onion packets used for payments, onion message packets can have payloads greater
  40         // than 1300 bytes.
  41         // TODO: if 1300 ends up being the most common size, optimize this to be:
  42         // enum { ThirteenHundred([u8; 1300]), VarLen(Vec<u8>) }
  43         pub(super) hop_data: Vec<u8>,
  44         pub(super) hmac: [u8; 32],
  45 }
  46
  47 impl onion_utils::Packet for Packet {
  48         type Data = Vec<u8>;
  49         fn new(public_key: PublicKey, hop_data: Vec<u8>, hmac: [u8; 32]) -> Packet {
  50                 Self {
  51                         version: 0,
  52                         public_key,
  53                         hop_data,
  54                         hmac,
  55                 }
  56         }
  57 }
  58
  59 impl Writeable for Packet {
  60         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  61                 self.version.write(w)?;
  62                 self.public_key.write(w)?;
  63                 w.write_all(&self.hop_data)?;
  64                 self.hmac.write(w)?;
  65                 Ok(())
  66         }
  67 }
  68
  69 impl LengthReadable for Packet {
  70         fn read<R: LengthRead>(r: &mut R) -> Result<Self, DecodeError> {
  71                 const READ_BUFFER_SIZE: usize = 4096;
  72
  73                 let version = Readable::read(r)?;
  74                 let public_key = Readable::read(r)?;
  75
  76                 let mut hop_data = Vec::new();
  77                 let hop_data_len = r.total_bytes().saturating_sub(66) as usize; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
  78                 let mut read_idx = 0;
  79                 while read_idx < hop_data_len {
  80                         let mut read_buffer = [0; READ_BUFFER_SIZE];
  81                         let read_amt = cmp::min(hop_data_len - read_idx, READ_BUFFER_SIZE);
  82                         r.read_exact(&mut read_buffer[..read_amt])?;
  83                         hop_data.extend_from_slice(&read_buffer[..read_amt]);
  84                         read_idx += read_amt;
  85                 }
  86
  87                 let hmac = Readable::read(r)?;
  88                 Ok(Packet {
  89                         version,
  90                         public_key,
  91                         hop_data,
  92                         hmac,
  93                 })
  94         }
  95 }
  96
  97 /// Onion message payloads contain "control" TLVs and "data" TLVs. Control TLVs are used to route
  98 /// the onion message from hop to hop and for path verification, whereas data TLVs contain the onion
  99 /// message content itself, such as an invoice request.
 100 pub(super) enum Payload<T: CustomOnionMessageContents> {
 101         /// This payload is for an intermediate hop.
 102         Forward(ForwardControlTlvs),
 103         /// This payload is for the final hop.
 104         Receive {
 105                 control_tlvs: ReceiveControlTlvs,
 106                 reply_path: Option<BlindedPath>,
 107                 message: OnionMessageContents<T>,
 108         }
 109 }
 110
 111 #[derive(Debug)]
 112 /// The contents of an onion message. In the context of offers, this would be the invoice, invoice
 113 /// request, or invoice error.
 114 pub enum OnionMessageContents<T: CustomOnionMessageContents> {
 115         /// A message related to BOLT 12 Offers.
 116         Offers(OffersMessage),
 117         /// A custom onion message specified by the user.
 118         Custom(T),
 119 }
 120
 121 impl<T: CustomOnionMessageContents> OnionMessageContents<T> {
 122         /// Returns the type that was used to decode the message payload.
 123         ///
 124         /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
 125         pub fn tlv_type(&self) -> u64 {
 126                 match self {
 127                         &OnionMessageContents::Offers(ref msg) => msg.tlv_type(),
 128                         &OnionMessageContents::Custom(ref msg) => msg.tlv_type(),
 129                 }
 130         }
 131 }
 132
 133 /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
 134 impl<T: CustomOnionMessageContents> Writeable for OnionMessageContents<T> {
 135         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 136                 match self {
 137                         OnionMessageContents::Offers(msg) => Ok(msg.write(w)?),
 138                         OnionMessageContents::Custom(msg) => Ok(msg.write(w)?),
 139                 }
 140         }
 141 }
 142
 143 /// The contents of a custom onion message.
 144 pub trait CustomOnionMessageContents: Writeable {
 145         /// Returns the TLV type identifying the message contents. MUST be >= 64.
 146         fn tlv_type(&self) -> u64;
 147 }
 148
 149 /// Forward control TLVs in their blinded and unblinded form.
 150 pub(super) enum ForwardControlTlvs {
 151         /// If we're sending to a blinded path, the node that constructed the blinded path has provided
 152         /// this hop's control TLVs, already encrypted into bytes.
 153         Blinded(Vec<u8>),
 154         /// If we're constructing an onion message hop through an intermediate unblinded node, we'll need
 155         /// to construct the intermediate hop's control TLVs in their unblinded state to avoid encoding
 156         /// them into an intermediate Vec. See [`crate::blinded_path::message::ForwardTlvs`] for more
 157         /// info.
 158         Unblinded(ForwardTlvs),
 159 }
 160
 161 /// Receive control TLVs in their blinded and unblinded form.
 162 pub(super) enum ReceiveControlTlvs {
 163         /// See [`ForwardControlTlvs::Blinded`].
 164         Blinded(Vec<u8>),
 165         /// See [`ForwardControlTlvs::Unblinded`] and [`crate::blinded_path::message::ReceiveTlvs`].
 166         Unblinded(ReceiveTlvs),
 167 }
 168
 169 // Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
 170 impl<T: CustomOnionMessageContents> Writeable for (Payload<T>, [u8; 32]) {
 171         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 172                 match &self.0 {
 173                         Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) => {
 174                                 _encode_varint_length_prefixed_tlv!(w, {
 175                                         (4, *encrypted_bytes, required_vec)
 176                                 })
 177                         },
 178                         Payload::Receive {
 179                                 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes), reply_path, message,
 180                         } => {
 181                                 _encode_varint_length_prefixed_tlv!(w, {
 182                                         (2, reply_path, option),
 183                                         (4, *encrypted_bytes, required_vec),
 184                                         (message.tlv_type(), message, required)
 185                                 })
 186                         },
 187                         Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
 188                                 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
 189                                 _encode_varint_length_prefixed_tlv!(w, {
 190                                         (4, write_adapter, required)
 191                                 })
 192                         },
 193                         Payload::Receive {
 194                                 control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs), reply_path, message,
 195                         } => {
 196                                 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
 197                                 _encode_varint_length_prefixed_tlv!(w, {
 198                                         (2, reply_path, option),
 199                                         (4, write_adapter, required),
 200                                         (message.tlv_type(), message, required)
 201                                 })
 202                         },
 203                 }
 204                 Ok(())
 205         }
 206 }
 207
 208 // Uses the provided secret to simultaneously decode and decrypt the control TLVs and data TLV.
 209 impl<H: CustomOnionMessageHandler + ?Sized, L: Logger + ?Sized>
 210 ReadableArgs<(SharedSecret, &H, &L)> for Payload<<H as CustomOnionMessageHandler>::CustomMessage> {
 211         fn read<R: Read>(r: &mut R, args: (SharedSecret, &H, &L)) -> Result<Self, DecodeError> {
 212                 let (encrypted_tlvs_ss, handler, logger) = args;
 213
 214                 let v: BigSize = Readable::read(r)?;
 215                 let mut rd = FixedLengthReader::new(r, v.0);
 216                 let mut reply_path: Option<BlindedPath> = None;
 217                 let mut read_adapter: Option<ChaChaPolyReadAdapter<ControlTlvs>> = None;
 218                 let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes());
 219                 let mut message_type: Option<u64> = None;
 220                 let mut message = None;
 221                 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
 222                         (2, reply_path, option),
 223                         (4, read_adapter, (option: LengthReadableArgs, rho)),
 224                 }, |msg_type, msg_reader| {
 225                         if msg_type < 64 { return Ok(false) }
 226                         // Don't allow reading more than one data TLV from an onion message.
 227                         if message_type.is_some() { return Err(DecodeError::InvalidValue) }
 228
 229                         message_type = Some(msg_type);
 230                         match msg_type {
 231                                 tlv_type if OffersMessage::is_known_type(tlv_type) => {
 232                                         let msg = OffersMessage::read(msg_reader, (tlv_type, logger))?;
 233                                         message = Some(OnionMessageContents::Offers(msg));
 234                                         Ok(true)
 235                                 },
 236                                 _ => match handler.read_custom_message(msg_type, msg_reader)? {
 237                                         Some(msg) => {
 238                                                 message = Some(OnionMessageContents::Custom(msg));
 239                                                 Ok(true)
 240                                         },
 241                                         None => Ok(false),
 242                                 },
 243                         }
 244                 });
 245                 rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
 246
 247                 match read_adapter {
 248                         None => return Err(DecodeError::InvalidValue),
 249                         Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(tlvs)}) => {
 250                                 if message_type.is_some() {
 251                                         return Err(DecodeError::InvalidValue)
 252                                 }
 253                                 Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
 254                         },
 255                         Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs)}) => {
 256                                 Ok(Payload::Receive {
 257                                         control_tlvs: ReceiveControlTlvs::Unblinded(tlvs),
 258                                         reply_path,
 259                                         message: message.ok_or(DecodeError::InvalidValue)?,
 260                                 })
 261                         },
 262                 }
 263         }
 264 }
 265
 266 /// When reading a packet off the wire, we don't know a priori whether the packet is to be forwarded
 267 /// or received. Thus we read a `ControlTlvs` rather than reading a [`ForwardTlvs`] or
 268 /// [`ReceiveTlvs`] directly. Also useful on the encoding side to keep forward and receive TLVs in
 269 /// the same iterator.
 270 pub(crate) enum ControlTlvs {
 271         /// This onion message is intended to be forwarded.
 272         Forward(ForwardTlvs),
 273         /// This onion message is intended to be received.
 274         Receive(ReceiveTlvs),
 275 }
 276
 277 impl Readable for ControlTlvs {
 278         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 279                 _init_and_read_tlv_stream!(r, {
 280                         (1, _padding, option),
 281                         (2, _short_channel_id, option),
 282                         (4, next_node_id, option),
 283                         (6, path_id, option),
 284                         (8, next_blinding_override, option),
 285                 });
 286                 let _padding: Option<Padding> = _padding;
 287                 let _short_channel_id: Option<u64> = _short_channel_id;
 288
 289                 let valid_fwd_fmt  = next_node_id.is_some() && path_id.is_none();
 290                 let valid_recv_fmt = next_node_id.is_none() && next_blinding_override.is_none();
 291
 292                 let payload_fmt = if valid_fwd_fmt {
 293                         ControlTlvs::Forward(ForwardTlvs {
 294                                 next_node_id: next_node_id.unwrap(),
 295                                 next_blinding_override,
 296                         })
 297                 } else if valid_recv_fmt {
 298                         ControlTlvs::Receive(ReceiveTlvs {
 299                                 path_id,
 300                         })
 301                 } else {
 302                         return Err(DecodeError::InvalidValue)
 303                 };
 304
 305                 Ok(payload_fmt)
 306         }
 307 }
 308
 309 impl Writeable for ControlTlvs {
 310         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 311                 match self {
 312                         Self::Forward(tlvs) => tlvs.write(w),
 313                         Self::Receive(tlvs) => tlvs.write(w),
 314                 }
 315         }
 316 }