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