_ 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::ln::msgs::DecodeError;
  18 use crate::ln::onion_utils;
  19 use super::messenger::CustomOnionMessageHandler;
  20 use super::offers::OffersMessage;
  21 use crate::util::chacha20poly1305rfc::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
  22 use crate::util::logger::Logger;
  23 use crate::util::ser::{BigSize, FixedLengthReader, LengthRead, LengthReadable, LengthReadableArgs, Readable, ReadableArgs, Writeable, Writer};
  24
  25 use core::cmp;
  26 use crate::io::{self, Read};
  27 use crate::prelude::*;
  28
  29 // Per the spec, an onion message packet's `hop_data` field length should be
  30 // SMALL_PACKET_HOP_DATA_LEN if it fits, else BIG_PACKET_HOP_DATA_LEN if it fits.
  31 pub(super) const SMALL_PACKET_HOP_DATA_LEN: usize = 1300;
  32 pub(super) const BIG_PACKET_HOP_DATA_LEN: usize = 32768;
  33
  34 #[derive(Clone, Debug, PartialEq, Eq)]
  35 pub(crate) struct Packet {
  36         pub(super) version: u8,
  37         pub(super) public_key: PublicKey,
  38         // Unlike the onion packets used for payments, onion message packets can have payloads greater
  39         // than 1300 bytes.
  40         // TODO: if 1300 ends up being the most common size, optimize this to be:
  41         // enum { ThirteenHundred([u8; 1300]), VarLen(Vec<u8>) }
  42         pub(super) hop_data: Vec<u8>,
  43         pub(super) hmac: [u8; 32],
  44 }
  45
  46 impl onion_utils::Packet for Packet {
  47         type Data = Vec<u8>;
  48         fn new(public_key: PublicKey, hop_data: Vec<u8>, hmac: [u8; 32]) -> Packet {
  49                 Self {
  50                         version: 0,
  51                         public_key,
  52                         hop_data,
  53                         hmac,
  54                 }
  55         }
  56 }
  57
  58 impl Writeable for Packet {
  59         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  60                 self.version.write(w)?;
  61                 self.public_key.write(w)?;
  62                 w.write_all(&self.hop_data)?;
  63                 self.hmac.write(w)?;
  64                 Ok(())
  65         }
  66 }
  67
  68 impl LengthReadable for Packet {
  69         fn read<R: LengthRead>(r: &mut R) -> Result<Self, DecodeError> {
  70                 const READ_BUFFER_SIZE: usize = 4096;
  71
  72                 let version = Readable::read(r)?;
  73                 let public_key = Readable::read(r)?;
  74
  75                 let mut hop_data = Vec::new();
  76                 let hop_data_len = r.total_bytes().saturating_sub(66) as usize; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
  77                 let mut read_idx = 0;
  78                 while read_idx < hop_data_len {
  79                         let mut read_buffer = [0; READ_BUFFER_SIZE];
  80                         let read_amt = cmp::min(hop_data_len - read_idx, READ_BUFFER_SIZE);
  81                         r.read_exact(&mut read_buffer[..read_amt])?;
  82                         hop_data.extend_from_slice(&read_buffer[..read_amt]);
  83                         read_idx += read_amt;
  84                 }
  85
  86                 let hmac = Readable::read(r)?;
  87                 Ok(Packet {
  88                         version,
  89                         public_key,
  90                         hop_data,
  91                         hmac,
  92                 })
  93         }
  94 }
  95
  96 /// Onion message payloads contain "control" TLVs and "data" TLVs. Control TLVs are used to route
  97 /// the onion message from hop to hop and for path verification, whereas data TLVs contain the onion
  98 /// message content itself, such as an invoice request.
  99 pub(super) enum Payload<T: CustomOnionMessageContents> {
 100         /// This payload is for an intermediate hop.
 101         Forward(ForwardControlTlvs),
 102         /// This payload is for the final hop.
 103         Receive {
 104                 control_tlvs: ReceiveControlTlvs,
 105                 reply_path: Option<BlindedPath>,
 106                 message: OnionMessageContents<T>,
 107         }
 108 }
 109
 110 #[derive(Debug)]
 111 /// The contents of an onion message. In the context of offers, this would be the invoice, invoice
 112 /// request, or invoice error.
 113 pub enum OnionMessageContents<T: CustomOnionMessageContents> {
 114         /// A message related to BOLT 12 Offers.
 115         Offers(OffersMessage),
 116         /// A custom onion message specified by the user.
 117         Custom(T),
 118 }
 119
 120 impl<T: CustomOnionMessageContents> OnionMessageContents<T> {
 121         /// Returns the type that was used to decode the message payload.
 122         ///
 123         /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
 124         pub fn tlv_type(&self) -> u64 {
 125                 match self {
 126                         &OnionMessageContents::Offers(ref msg) => msg.tlv_type(),
 127                         &OnionMessageContents::Custom(ref msg) => msg.tlv_type(),
 128                 }
 129         }
 130 }
 131
 132 /// This is not exported to bindings users as methods on non-cloneable enums are not currently exportable
 133 impl<T: CustomOnionMessageContents> Writeable for OnionMessageContents<T> {
 134         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 135                 match self {
 136                         OnionMessageContents::Offers(msg) => Ok(msg.write(w)?),
 137                         OnionMessageContents::Custom(msg) => Ok(msg.write(w)?),
 138                 }
 139         }
 140 }
 141
 142 /// The contents of a custom onion message.
 143 pub trait CustomOnionMessageContents: Writeable {
 144         /// Returns the TLV type identifying the message contents. MUST be >= 64.
 145         fn tlv_type(&self) -> u64;
 146 }
 147
 148 /// Forward control TLVs in their blinded and unblinded form.
 149 pub(super) enum ForwardControlTlvs {
 150         /// If we're sending to a blinded path, the node that constructed the blinded path has provided
 151         /// this hop's control TLVs, already encrypted into bytes.
 152         Blinded(Vec<u8>),
 153         /// If we're constructing an onion message hop through an intermediate unblinded node, we'll need
 154         /// to construct the intermediate hop's control TLVs in their unblinded state to avoid encoding
 155         /// them into an intermediate Vec. See [`crate::blinded_path::message::ForwardTlvs`] for more
 156         /// info.
 157         Unblinded(ForwardTlvs),
 158 }
 159
 160 /// Receive control TLVs in their blinded and unblinded form.
 161 pub(super) enum ReceiveControlTlvs {
 162         /// See [`ForwardControlTlvs::Blinded`].
 163         Blinded(Vec<u8>),
 164         /// See [`ForwardControlTlvs::Unblinded`] and [`crate::blinded_path::message::ReceiveTlvs`].
 165         Unblinded(ReceiveTlvs),
 166 }
 167
 168 // Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
 169 impl<T: CustomOnionMessageContents> Writeable for (Payload<T>, [u8; 32]) {
 170         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 171                 match &self.0 {
 172                         Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) => {
 173                                 _encode_varint_length_prefixed_tlv!(w, {
 174                                         (4, *encrypted_bytes, required_vec)
 175                                 })
 176                         },
 177                         Payload::Receive {
 178                                 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes), reply_path, message,
 179                         } => {
 180                                 _encode_varint_length_prefixed_tlv!(w, {
 181                                         (2, reply_path, option),
 182                                         (4, *encrypted_bytes, required_vec),
 183                                         (message.tlv_type(), message, required)
 184                                 })
 185                         },
 186                         Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
 187                                 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
 188                                 _encode_varint_length_prefixed_tlv!(w, {
 189                                         (4, write_adapter, required)
 190                                 })
 191                         },
 192                         Payload::Receive {
 193                                 control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs), reply_path, message,
 194                         } => {
 195                                 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
 196                                 _encode_varint_length_prefixed_tlv!(w, {
 197                                         (2, reply_path, option),
 198                                         (4, write_adapter, required),
 199                                         (message.tlv_type(), message, required)
 200                                 })
 201                         },
 202                 }
 203                 Ok(())
 204         }
 205 }
 206
 207 // Uses the provided secret to simultaneously decode and decrypt the control TLVs and data TLV.
 208 impl<H: CustomOnionMessageHandler + ?Sized, L: Logger + ?Sized>
 209 ReadableArgs<(SharedSecret, &H, &L)> for Payload<<H as CustomOnionMessageHandler>::CustomMessage> {
 210         fn read<R: Read>(r: &mut R, args: (SharedSecret, &H, &L)) -> Result<Self, DecodeError> {
 211                 let (encrypted_tlvs_ss, handler, logger) = args;
 212
 213                 let v: BigSize = Readable::read(r)?;
 214                 let mut rd = FixedLengthReader::new(r, v.0);
 215                 let mut reply_path: Option<BlindedPath> = None;
 216                 let mut read_adapter: Option<ChaChaPolyReadAdapter<ControlTlvs>> = None;
 217                 let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes());
 218                 let mut message_type: Option<u64> = None;
 219                 let mut message = None;
 220                 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
 221                         (2, reply_path, option),
 222                         (4, read_adapter, (option: LengthReadableArgs, rho)),
 223                 }, |msg_type, msg_reader| {
 224                         if msg_type < 64 { return Ok(false) }
 225                         // Don't allow reading more than one data TLV from an onion message.
 226                         if message_type.is_some() { return Err(DecodeError::InvalidValue) }
 227
 228                         message_type = Some(msg_type);
 229                         match msg_type {
 230                                 tlv_type if OffersMessage::is_known_type(tlv_type) => {
 231                                         let msg = OffersMessage::read(msg_reader, (tlv_type, logger))?;
 232                                         message = Some(OnionMessageContents::Offers(msg));
 233                                         Ok(true)
 234                                 },
 235                                 _ => match handler.read_custom_message(msg_type, msg_reader)? {
 236                                         Some(msg) => {
 237                                                 message = Some(OnionMessageContents::Custom(msg));
 238                                                 Ok(true)
 239                                         },
 240                                         None => Ok(false),
 241                                 },
 242                         }
 243                 });
 244                 rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
 245
 246                 match read_adapter {
 247                         None => return Err(DecodeError::InvalidValue),
 248                         Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(tlvs)}) => {
 249                                 if message_type.is_some() {
 250                                         return Err(DecodeError::InvalidValue)
 251                                 }
 252                                 Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
 253                         },
 254                         Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs)}) => {
 255                                 Ok(Payload::Receive {
 256                                         control_tlvs: ReceiveControlTlvs::Unblinded(tlvs),
 257                                         reply_path,
 258                                         message: message.ok_or(DecodeError::InvalidValue)?,
 259                                 })
 260                         },
 261                 }
 262         }
 263 }
 264
 265 /// When reading a packet off the wire, we don't know a priori whether the packet is to be forwarded
 266 /// or received. Thus we read a ControlTlvs rather than reading a ForwardControlTlvs or
 267 /// ReceiveControlTlvs directly.
 268 pub(crate) enum ControlTlvs {
 269         /// This onion message is intended to be forwarded.
 270         Forward(ForwardTlvs),
 271         /// This onion message is intended to be received.
 272         Receive(ReceiveTlvs),
 273 }
 274
 275 impl Readable for ControlTlvs {
 276         fn read<R: Read>(mut r: &mut R) -> Result<Self, DecodeError> {
 277                 let mut _padding: Option<Padding> = None;
 278                 let mut _short_channel_id: Option<u64> = None;
 279                 let mut next_node_id: Option<PublicKey> = None;
 280                 let mut path_id: Option<[u8; 32]> = None;
 281                 let mut next_blinding_override: Option<PublicKey> = None;
 282                 decode_tlv_stream!(&mut r, {
 283                         (1, _padding, option),
 284                         (2, _short_channel_id, option),
 285                         (4, next_node_id, option),
 286                         (6, path_id, option),
 287                         (8, next_blinding_override, option),
 288                 });
 289
 290                 let valid_fwd_fmt  = next_node_id.is_some() && path_id.is_none();
 291                 let valid_recv_fmt = next_node_id.is_none() && next_blinding_override.is_none();
 292
 293                 let payload_fmt = if valid_fwd_fmt {
 294                         ControlTlvs::Forward(ForwardTlvs {
 295                                 next_node_id: next_node_id.unwrap(),
 296                                 next_blinding_override,
 297                         })
 298                 } else if valid_recv_fmt {
 299                         ControlTlvs::Receive(ReceiveTlvs {
 300                                 path_id,
 301                         })
 302                 } else {
 303                         return Err(DecodeError::InvalidValue)
 304                 };
 305
 306                 Ok(payload_fmt)
 307         }
 308 }
 309
 310 /// Reads padding to the end, ignoring what's read.
 311 pub(crate) struct Padding {}
 312 impl Readable for Padding {
 313         #[inline]
 314         fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
 315                 loop {
 316                         let mut buf = [0; 8192];
 317                         if reader.read(&mut buf[..])? == 0 { break; }
 318                 }
 319                 Ok(Self {})
 320         }
 321 }