_ Git - rust-lightning/blob - lightning/src/onion_message/messenger.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 //! LDK sends, receives, and forwards onion messages via the [`OnionMessenger`]. See its docs for
  11 //! more information.
  12
  13 use bitcoin::hashes::{Hash, HashEngine};
  14 use bitcoin::hashes::hmac::{Hmac, HmacEngine};
  15 use bitcoin::hashes::sha256::Hash as Sha256;
  16 use bitcoin::secp256k1::{self, PublicKey, Scalar, Secp256k1, SecretKey};
  17
  18 use crate::blinded_path::BlindedPath;
  19 use crate::blinded_path::message::{advance_path_by_one, ForwardTlvs, ReceiveTlvs};
  20 use crate::blinded_path::utils;
  21 use crate::sign::{EntropySource, KeysManager, NodeSigner, Recipient};
  22 use crate::events::OnionMessageProvider;
  23 use crate::ln::features::{InitFeatures, NodeFeatures};
  24 use crate::ln::msgs::{self, OnionMessageHandler};
  25 use crate::ln::onion_utils;
  26 use crate::ln::peer_handler::IgnoringMessageHandler;
  27 pub use super::packet::{CustomOnionMessageContents, OnionMessageContents};
  28 use super::offers::OffersMessageHandler;
  29 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  30 use crate::util::logger::Logger;
  31 use crate::util::ser::Writeable;
  32
  33 use core::ops::Deref;
  34 use crate::io;
  35 use crate::sync::{Arc, Mutex};
  36 use crate::prelude::*;
  37
  38 /// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be
  39 /// used to retrieve invoices and fulfill invoice requests from [offers]. Currently, only sending
  40 /// and receiving custom onion messages is supported.
  41 ///
  42 /// # Example
  43 ///
  44 /// ```
  45 /// # extern crate bitcoin;
  46 /// # use bitcoin::hashes::_export::_core::time::Duration;
  47 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
  48 /// # use lightning::blinded_path::BlindedPath;
  49 /// # use lightning::sign::KeysManager;
  50 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  51 /// # use lightning::onion_message::{CustomOnionMessageContents, Destination, MessageRouter, OnionMessageContents, OnionMessagePath, OnionMessenger};
  52 /// # use lightning::util::logger::{Logger, Record};
  53 /// # use lightning::util::ser::{Writeable, Writer};
  54 /// # use lightning::io;
  55 /// # use std::sync::Arc;
  56 /// # struct FakeLogger;
  57 /// # impl Logger for FakeLogger {
  58 /// #     fn log(&self, record: &Record) { unimplemented!() }
  59 /// # }
  60 /// # struct FakeMessageRouter {}
  61 /// # impl MessageRouter for FakeMessageRouter {
  62 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  63 /// #         unimplemented!()
  64 /// #     }
  65 /// # }
  66 /// # let seed = [42u8; 32];
  67 /// # let time = Duration::from_secs(123456);
  68 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
  69 /// # let logger = Arc::new(FakeLogger {});
  70 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  71 /// # let secp_ctx = Secp256k1::new();
  72 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  73 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
  74 /// # let destination_node_id = hop_node_id1;
  75 /// # let message_router = Arc::new(FakeMessageRouter {});
  76 /// # let custom_message_handler = IgnoringMessageHandler {};
  77 /// # let offers_message_handler = IgnoringMessageHandler {};
  78 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
  79 /// // ChannelManager.
  80 /// let onion_messenger = OnionMessenger::new(
  81 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
  82 ///     &custom_message_handler
  83 /// );
  84 ///
  85 /// # struct YourCustomMessage {}
  86 /// impl Writeable for YourCustomMessage {
  87 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  88 ///             # Ok(())
  89 ///             // Write your custom onion message to `w`
  90 ///     }
  91 /// }
  92 /// impl CustomOnionMessageContents for YourCustomMessage {
  93 ///     fn tlv_type(&self) -> u64 {
  94 ///             # let your_custom_message_type = 42;
  95 ///             your_custom_message_type
  96 ///     }
  97 /// }
  98 /// // Send a custom onion message to a node id.
  99 /// let path = OnionMessagePath {
 100 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 101 ///     destination: Destination::Node(destination_node_id),
 102 /// };
 103 /// let reply_path = None;
 104 /// # let your_custom_message = YourCustomMessage {};
 105 /// let message = OnionMessageContents::Custom(your_custom_message);
 106 /// onion_messenger.send_onion_message(path, message, reply_path);
 107 ///
 108 /// // Create a blinded path to yourself, for someone to send an onion message to.
 109 /// # let your_node_id = hop_node_id1;
 110 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 111 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 112 ///
 113 /// // Send a custom onion message to a blinded path.
 114 /// let path = OnionMessagePath {
 115 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 116 ///     destination: Destination::BlindedPath(blinded_path),
 117 /// };
 118 /// let reply_path = None;
 119 /// # let your_custom_message = YourCustomMessage {};
 120 /// let message = OnionMessageContents::Custom(your_custom_message);
 121 /// onion_messenger.send_onion_message(path, message, reply_path);
 122 /// ```
 123 ///
 124 /// [offers]: <https://github.com/lightning/bolts/pull/798>
 125 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
 126 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 127 where
 128         ES::Target: EntropySource,
 129         NS::Target: NodeSigner,
 130         L::Target: Logger,
 131         MR::Target: MessageRouter,
 132         OMH::Target: OffersMessageHandler,
 133         CMH:: Target: CustomOnionMessageHandler,
 134 {
 135         entropy_source: ES,
 136         node_signer: NS,
 137         logger: L,
 138         pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
 139         secp_ctx: Secp256k1<secp256k1::All>,
 140         message_router: MR,
 141         offers_handler: OMH,
 142         custom_handler: CMH,
 143 }
 144
 145 /// A trait defining behavior for routing an [`OnionMessage`].
 146 ///
 147 /// [`OnionMessage`]: msgs::OnionMessage
 148 pub trait MessageRouter {
 149         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 150         ///
 151         /// [`OnionMessage`]: msgs::OnionMessage
 152         fn find_path(
 153                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 154         ) -> Result<OnionMessagePath, ()>;
 155 }
 156
 157 /// A [`MessageRouter`] that always fails.
 158 pub struct DefaultMessageRouter;
 159
 160 impl MessageRouter for DefaultMessageRouter {
 161         fn find_path(
 162                 &self, _sender: PublicKey, _peers: Vec<PublicKey>, _destination: Destination
 163         ) -> Result<OnionMessagePath, ()> {
 164                 Err(())
 165         }
 166 }
 167
 168 /// A path for sending an [`msgs::OnionMessage`].
 169 #[derive(Clone)]
 170 pub struct OnionMessagePath {
 171         /// Nodes on the path between the sender and the destination.
 172         pub intermediate_nodes: Vec<PublicKey>,
 173
 174         /// The recipient of the message.
 175         pub destination: Destination,
 176 }
 177
 178 /// The destination of an onion message.
 179 #[derive(Clone)]
 180 pub enum Destination {
 181         /// We're sending this onion message to a node.
 182         Node(PublicKey),
 183         /// We're sending this onion message to a blinded path.
 184         BlindedPath(BlindedPath),
 185 }
 186
 187 impl Destination {
 188         pub(super) fn num_hops(&self) -> usize {
 189                 match self {
 190                         Destination::Node(_) => 1,
 191                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 192                 }
 193         }
 194 }
 195
 196 /// Errors that may occur when [sending an onion message].
 197 ///
 198 /// [sending an onion message]: OnionMessenger::send_onion_message
 199 #[derive(Debug, PartialEq, Eq)]
 200 pub enum SendError {
 201         /// Errored computing onion message packet keys.
 202         Secp256k1(secp256k1::Error),
 203         /// Because implementations such as Eclair will drop onion messages where the message packet
 204         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 205         TooBigPacket,
 206         /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two
 207         /// blinded hops.
 208         TooFewBlindedHops,
 209         /// Our next-hop peer was offline or does not support onion message forwarding.
 210         InvalidFirstHop,
 211         /// Onion message contents must have a TLV type >= 64.
 212         InvalidMessage,
 213         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 214         BufferFull,
 215         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 216         ///
 217         /// [`NodeSigner`]: crate::sign::NodeSigner
 218         GetNodeIdFailed,
 219         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 220         /// advance the blinded path to make the second hop the new introduction node. Either
 221         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 222         /// new blinding point, or we were attempting to send to ourselves.
 223         BlindedPathAdvanceFailed,
 224 }
 225
 226 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 227 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 228 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 229 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 230 /// message types.
 231 ///
 232 /// See [`OnionMessenger`] for example usage.
 233 ///
 234 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 235 /// [`CustomMessage`]: Self::CustomMessage
 236 pub trait CustomOnionMessageHandler {
 237         /// The message known to the handler. To support multiple message types, you may want to make this
 238         /// an enum with a variant for each supported message.
 239         type CustomMessage: CustomOnionMessageContents;
 240
 241         /// Called with the custom message that was received, returning a response to send, if any.
 242         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 243
 244         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 245         /// message type is unknown.
 246         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 247 }
 248
 249 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 250 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 251 where
 252         ES::Target: EntropySource,
 253         NS::Target: NodeSigner,
 254         L::Target: Logger,
 255         MR::Target: MessageRouter,
 256         OMH::Target: OffersMessageHandler,
 257         CMH::Target: CustomOnionMessageHandler,
 258 {
 259         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 260         /// their respective handlers.
 261         pub fn new(
 262                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 263                 custom_handler: CMH
 264         ) -> Self {
 265                 let mut secp_ctx = Secp256k1::new();
 266                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 267                 OnionMessenger {
 268                         entropy_source,
 269                         node_signer,
 270                         pending_messages: Mutex::new(HashMap::new()),
 271                         secp_ctx,
 272                         logger,
 273                         message_router,
 274                         offers_handler,
 275                         custom_handler,
 276                 }
 277         }
 278
 279         /// Send an onion message with contents `message` to the destination of `path`.
 280         ///
 281         /// See [`OnionMessenger`] for example usage.
 282         pub fn send_onion_message<T: CustomOnionMessageContents>(
 283                 &self, path: OnionMessagePath, message: OnionMessageContents<T>,
 284                 reply_path: Option<BlindedPath>
 285         ) -> Result<(), SendError> {
 286                 let (introduction_node_id, onion_msg) = Self::create_onion_message(
 287                         &self.entropy_source,
 288                         &self.node_signer,
 289                         &self.secp_ctx,
 290                         path,
 291                         message,
 292                         reply_path
 293                 )?;
 294
 295                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 296                 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
 297                 match pending_per_peer_msgs.entry(introduction_node_id) {
 298                         hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
 299                         hash_map::Entry::Occupied(mut e) => {
 300                                 e.get_mut().push_back(onion_msg);
 301                                 Ok(())
 302                         }
 303                 }
 304         }
 305
 306         /// Create an onion message with contents `message` to the destination of `path`.
 307         /// Returns (introduction_node_id, onion_msg)
 308         pub fn create_onion_message<T: CustomOnionMessageContents>(
 309                 entropy_source: &ES,
 310                 node_signer: &NS,
 311                 secp_ctx: &Secp256k1<secp256k1::All>,
 312                 path: OnionMessagePath,
 313                 message: OnionMessageContents<T>,
 314                 reply_path: Option<BlindedPath>,
 315         ) -> Result<(PublicKey, msgs::OnionMessage), SendError> {
 316                 let OnionMessagePath { intermediate_nodes, mut destination } = path;
 317                 if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 318                         if blinded_hops.len() < 2 {
 319                                 return Err(SendError::TooFewBlindedHops);
 320                         }
 321                 }
 322
 323                 if message.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 324
 325                 // If we are sending straight to a blinded path and we are the introduction node, we need to
 326                 // advance the blinded path by 1 hop so the second hop is the new introduction node.
 327                 if intermediate_nodes.len() == 0 {
 328                         if let Destination::BlindedPath(ref mut blinded_path) = destination {
 329                                 let our_node_id = node_signer.get_node_id(Recipient::Node)
 330                                         .map_err(|()| SendError::GetNodeIdFailed)?;
 331                                 if blinded_path.introduction_node_id == our_node_id {
 332                                         advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 333                                                 .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 334                                 }
 335                         }
 336                 }
 337
 338                 let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 339                 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 340                 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
 341                         (intermediate_nodes[0], PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 342                 } else {
 343                         match destination {
 344                                 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 345                                 Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 346                                         (introduction_node_id, blinding_point),
 347                         }
 348                 };
 349                 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 350                         &secp_ctx, &intermediate_nodes, destination, message, reply_path, &blinding_secret)
 351                         .map_err(|e| SendError::Secp256k1(e))?;
 352
 353                 let prng_seed = entropy_source.get_secure_random_bytes();
 354                 let onion_routing_packet = construct_onion_message_packet(
 355                         packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 356
 357                 Ok((introduction_node_id, msgs::OnionMessage {
 358                         blinding_point,
 359                         onion_routing_packet
 360                 }))
 361         }
 362
 363         fn respond_with_onion_message<T: CustomOnionMessageContents>(
 364                 &self, response: OnionMessageContents<T>, path_id: Option<[u8; 32]>,
 365                 reply_path: Option<BlindedPath>
 366         ) {
 367                 let sender = match self.node_signer.get_node_id(Recipient::Node) {
 368                         Ok(node_id) => node_id,
 369                         Err(_) => {
 370                                 log_warn!(
 371                                         self.logger, "Unable to retrieve node id when responding to onion message with \
 372                                         path_id {:02x?}", path_id
 373                                 );
 374                                 return;
 375                         }
 376                 };
 377
 378                 let peers = self.pending_messages.lock().unwrap().keys().copied().collect();
 379
 380                 let destination = match reply_path {
 381                         Some(reply_path) => Destination::BlindedPath(reply_path),
 382                         None => {
 383                                 log_trace!(
 384                                         self.logger, "Missing reply path when responding to onion message with path_id \
 385                                         {:02x?}", path_id
 386                                 );
 387                                 return;
 388                         },
 389                 };
 390
 391                 let path = match self.message_router.find_path(sender, peers, destination) {
 392                         Ok(path) => path,
 393                         Err(()) => {
 394                                 log_trace!(
 395                                         self.logger, "Failed to find path when responding to onion message with \
 396                                         path_id {:02x?}", path_id
 397                                 );
 398                                 return;
 399                         },
 400                 };
 401
 402                 log_trace!(self.logger, "Responding to onion message with path_id {:02x?}", path_id);
 403
 404                 if let Err(e) = self.send_onion_message(path, response, None) {
 405                         log_trace!(
 406                                 self.logger, "Failed responding to onion message with path_id {:02x?}: {:?}",
 407                                 path_id, e
 408                         );
 409                         return;
 410                 }
 411         }
 412
 413         #[cfg(test)]
 414         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
 415                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 416                 let mut msgs = HashMap::new();
 417                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 418                 // swap the pending message buffers individually.
 419                 for (peer_node_id, pending_messages) in &mut *pending_msgs {
 420                         msgs.insert(*peer_node_id, core::mem::take(pending_messages));
 421                 }
 422                 msgs
 423         }
 424 }
 425
 426 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
 427         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 428         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 429         let mut total_buffered_bytes = 0;
 430         let mut peer_buffered_bytes = 0;
 431         for (pk, peer_buf) in buffer {
 432                 for om in peer_buf {
 433                         let om_len = om.serialized_length();
 434                         if pk == peer_node_id {
 435                                 peer_buffered_bytes += om_len;
 436                         }
 437                         total_buffered_bytes += om_len;
 438
 439                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 440                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 441                         {
 442                                 return true
 443                         }
 444                 }
 445         }
 446         false
 447 }
 448
 449 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 450 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 451 where
 452         ES::Target: EntropySource,
 453         NS::Target: NodeSigner,
 454         L::Target: Logger,
 455         MR::Target: MessageRouter,
 456         OMH::Target: OffersMessageHandler,
 457         CMH::Target: CustomOnionMessageHandler,
 458 {
 459         /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
 460         /// soon we'll delegate the onion message to a handler that can generate invoices or send
 461         /// payments.
 462         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
 463                 let control_tlvs_ss = match self.node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 464                         Ok(ss) => ss,
 465                         Err(e) =>  {
 466                                 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
 467                                 return
 468                         }
 469                 };
 470                 let onion_decode_ss = {
 471                         let blinding_factor = {
 472                                 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 473                                 hmac.input(control_tlvs_ss.as_ref());
 474                                 Hmac::from_engine(hmac).into_inner()
 475                         };
 476                         match self.node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 477                                 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 478                         {
 479                                 Ok(ss) => ss.secret_bytes(),
 480                                 Err(()) => {
 481                                         log_trace!(self.logger, "Failed to compute onion packet shared secret");
 482                                         return
 483                                 }
 484                         }
 485                 };
 486                 match onion_utils::decode_next_untagged_hop(
 487                         onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 488                         (control_tlvs_ss, &*self.custom_handler, &*self.logger)
 489                 ) {
 490                         Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
 491                                 message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 492                         }, None)) => {
 493                                 log_trace!(self.logger,
 494                                         "Received an onion message with path_id {:02x?} and {} reply_path",
 495                                                 path_id, if reply_path.is_some() { "a" } else { "no" });
 496
 497                                 let response = match message {
 498                                         OnionMessageContents::Offers(msg) => {
 499                                                 self.offers_handler.handle_message(msg)
 500                                                         .map(|msg| OnionMessageContents::Offers(msg))
 501                                         },
 502                                         OnionMessageContents::Custom(msg) => {
 503                                                 self.custom_handler.handle_custom_message(msg)
 504                                                         .map(|msg| OnionMessageContents::Custom(msg))
 505                                         },
 506                                 };
 507
 508                                 if let Some(response) = response {
 509                                         self.respond_with_onion_message(response, path_id, reply_path);
 510                                 }
 511                         },
 512                         Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 513                                 next_node_id, next_blinding_override
 514                         })), Some((next_hop_hmac, new_packet_bytes)))) => {
 515                                 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 516                                 // blinded hop and this onion message is destined for us. In this situation, we should keep
 517                                 // unwrapping the onion layers to get to the final payload. Since we don't have the option
 518                                 // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 519                                 // for now.
 520                                 let new_pubkey = match onion_utils::next_hop_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 521                                         Ok(pk) => pk,
 522                                         Err(e) => {
 523                                                 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
 524                                                 return
 525                                         }
 526                                 };
 527                                 let outgoing_packet = Packet {
 528                                         version: 0,
 529                                         public_key: new_pubkey,
 530                                         hop_data: new_packet_bytes,
 531                                         hmac: next_hop_hmac,
 532                                 };
 533                                 let onion_message = msgs::OnionMessage {
 534                                         blinding_point: match next_blinding_override {
 535                                                 Some(blinding_point) => blinding_point,
 536                                                 None => {
 537                                                         match onion_utils::next_hop_pubkey(
 538                                                                 &self.secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 539                                                         ) {
 540                                                                 Ok(bp) => bp,
 541                                                                 Err(e) => {
 542                                                                         log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
 543                                                                         return
 544                                                                 }
 545                                                         }
 546                                                 }
 547                                         },
 548                                         onion_routing_packet: outgoing_packet,
 549                                 };
 550
 551                                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 552                                 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
 553                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 554                                         return
 555                                 }
 556
 557                                 #[cfg(fuzzing)]
 558                                 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
 559
 560                                 match pending_per_peer_msgs.entry(next_node_id) {
 561                                         hash_map::Entry::Vacant(_) => {
 562                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 563                                                 return
 564                                         },
 565                                         hash_map::Entry::Occupied(mut e) => {
 566                                                 e.get_mut().push_back(onion_message);
 567                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 568                                         }
 569                                 };
 570                         },
 571                         Err(e) => {
 572                                 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
 573                         },
 574                         _ => {
 575                                 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 576                         },
 577                 };
 578         }
 579
 580         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 581                 if init.features.supports_onion_messages() {
 582                         let mut peers = self.pending_messages.lock().unwrap();
 583                         peers.insert(their_node_id.clone(), VecDeque::new());
 584                 }
 585                 Ok(())
 586         }
 587
 588         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 589                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 590                 pending_msgs.remove(their_node_id);
 591         }
 592
 593         fn provided_node_features(&self) -> NodeFeatures {
 594                 let mut features = NodeFeatures::empty();
 595                 features.set_onion_messages_optional();
 596                 features
 597         }
 598
 599         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
 600                 let mut features = InitFeatures::empty();
 601                 features.set_onion_messages_optional();
 602                 features
 603         }
 604 }
 605
 606 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageProvider
 607 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 608 where
 609         ES::Target: EntropySource,
 610         NS::Target: NodeSigner,
 611         L::Target: Logger,
 612         MR::Target: MessageRouter,
 613         OMH::Target: OffersMessageHandler,
 614         CMH::Target: CustomOnionMessageHandler,
 615 {
 616         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
 617                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 618                 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
 619                         return msgs.pop_front()
 620                 }
 621                 None
 622         }
 623 }
 624
 625 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
 626 // produces
 627 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 628 /// [`SimpleArcPeerManager`]. See their docs for more details.
 629 ///
 630 /// This is not exported to bindings users as `Arc`s don't make sense in bindings.
 631 ///
 632 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 633 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
 634 pub type SimpleArcOnionMessenger<L> = OnionMessenger<
 635         Arc<KeysManager>,
 636         Arc<KeysManager>,
 637         Arc<L>,
 638         Arc<DefaultMessageRouter>,
 639         IgnoringMessageHandler,
 640         IgnoringMessageHandler
 641 >;
 642
 643 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 644 /// [`SimpleRefPeerManager`]. See their docs for more details.
 645 ///
 646 /// This is not exported to bindings users as general type aliases don't make sense in bindings.
 647 ///
 648 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 649 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
 650 pub type SimpleRefOnionMessenger<'a, 'b, 'c, L> = OnionMessenger<
 651         &'a KeysManager,
 652         &'a KeysManager,
 653         &'b L,
 654         &'c DefaultMessageRouter,
 655         IgnoringMessageHandler,
 656         IgnoringMessageHandler
 657 >;
 658
 659 /// Construct onion packet payloads and keys for sending an onion message along the given
 660 /// `unblinded_path` to the given `destination`.
 661 fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
 662         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
 663         message: OnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 664 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 665         let num_hops = unblinded_path.len() + destination.num_hops();
 666         let mut payloads = Vec::with_capacity(num_hops);
 667         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 668
 669         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
 670                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 671                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 672         let num_unblinded_hops = num_hops - num_blinded_hops;
 673
 674         let mut unblinded_path_idx = 0;
 675         let mut blinded_path_idx = 0;
 676         let mut prev_control_tlvs_ss = None;
 677         let mut final_control_tlvs = None;
 678         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
 679                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
 680                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 681                                 if let Some(ss) = prev_control_tlvs_ss.take() {
 682                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
 683                                                 ForwardTlvs {
 684                                                         next_node_id: unblinded_pk_opt.unwrap(),
 685                                                         next_blinding_override: None,
 686                                                 }
 687                                         )), ss));
 688                                 }
 689                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 690                                 unblinded_path_idx += 1;
 691                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
 692                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
 693                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 694                                                 next_node_id: intro_node_id,
 695                                                 next_blinding_override: Some(blinding_pt),
 696                                         })), control_tlvs_ss));
 697                                 }
 698                         }
 699                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
 700                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
 701                                         control_tlvs_ss));
 702                                 blinded_path_idx += 1;
 703                         } else if let Some(encrypted_payload) = enc_payload_opt {
 704                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
 705                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 706                         }
 707
 708                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
 709                         onion_packet_keys.push(onion_utils::OnionKeys {
 710                                 #[cfg(test)]
 711                                 shared_secret: onion_packet_ss,
 712                                 #[cfg(test)]
 713                                 blinding_factor: [0; 32],
 714                                 ephemeral_pubkey,
 715                                 rho,
 716                                 mu,
 717                         });
 718                 }
 719         )?;
 720
 721         if let Some(control_tlvs) = final_control_tlvs {
 722                 payloads.push((Payload::Receive {
 723                         control_tlvs,
 724                         reply_path: reply_path.take(),
 725                         message,
 726                 }, prev_control_tlvs_ss.unwrap()));
 727         } else {
 728                 payloads.push((Payload::Receive {
 729                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
 730                         reply_path: reply_path.take(),
 731                         message,
 732                 }, prev_control_tlvs_ss.unwrap()));
 733         }
 734
 735         Ok((payloads, onion_packet_keys))
 736 }
 737
 738 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
 739 fn construct_onion_message_packet<T: CustomOnionMessageContents>(payloads: Vec<(Payload<T>, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
 740         // Spec rationale:
 741         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
 742         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
 743         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
 744         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
 745         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
 746                 SMALL_PACKET_HOP_DATA_LEN
 747         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
 748                 BIG_PACKET_HOP_DATA_LEN
 749         } else { return Err(()) };
 750
 751         onion_utils::construct_onion_message_packet::<_, _>(
 752                 payloads, onion_keys, prng_seed, hop_data_len)
 753 }