_ 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
 250 /// Create an onion message with contents `message` to the destination of `path`.
 251 /// Returns (introduction_node_id, onion_msg)
 252 pub fn create_onion_message<ES: Deref, NS: Deref, T: CustomOnionMessageContents>(
 253         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 254         path: OnionMessagePath, message: OnionMessageContents<T>, reply_path: Option<BlindedPath>,
 255 ) -> Result<(PublicKey, msgs::OnionMessage), SendError>
 256 where
 257         ES::Target: EntropySource,
 258         NS::Target: NodeSigner,
 259 {
 260         let OnionMessagePath { intermediate_nodes, mut destination } = path;
 261         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 262                 if blinded_hops.len() < 2 {
 263                         return Err(SendError::TooFewBlindedHops);
 264                 }
 265         }
 266
 267         if message.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 268
 269         // If we are sending straight to a blinded path and we are the introduction node, we need to
 270         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 271         if intermediate_nodes.len() == 0 {
 272                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 273                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 274                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 275                         if blinded_path.introduction_node_id == our_node_id {
 276                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 277                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 278                         }
 279                 }
 280         }
 281
 282         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 283         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 284         let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
 285                 (intermediate_nodes[0], PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 286         } else {
 287                 match destination {
 288                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 289                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 290                                 (introduction_node_id, blinding_point),
 291                 }
 292         };
 293         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 294                 &secp_ctx, &intermediate_nodes, destination, message, reply_path, &blinding_secret)
 295                 .map_err(|e| SendError::Secp256k1(e))?;
 296
 297         let prng_seed = entropy_source.get_secure_random_bytes();
 298         let onion_routing_packet = construct_onion_message_packet(
 299                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 300
 301         Ok((introduction_node_id, msgs::OnionMessage {
 302                 blinding_point,
 303                 onion_routing_packet
 304         }))
 305 }
 306
 307 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 308 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 309 where
 310         ES::Target: EntropySource,
 311         NS::Target: NodeSigner,
 312         L::Target: Logger,
 313         MR::Target: MessageRouter,
 314         OMH::Target: OffersMessageHandler,
 315         CMH::Target: CustomOnionMessageHandler,
 316 {
 317         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 318         /// their respective handlers.
 319         pub fn new(
 320                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 321                 custom_handler: CMH
 322         ) -> Self {
 323                 let mut secp_ctx = Secp256k1::new();
 324                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 325                 OnionMessenger {
 326                         entropy_source,
 327                         node_signer,
 328                         pending_messages: Mutex::new(HashMap::new()),
 329                         secp_ctx,
 330                         logger,
 331                         message_router,
 332                         offers_handler,
 333                         custom_handler,
 334                 }
 335         }
 336
 337         /// Send an onion message with contents `message` to the destination of `path`.
 338         ///
 339         /// See [`OnionMessenger`] for example usage.
 340         pub fn send_onion_message<T: CustomOnionMessageContents>(
 341                 &self, path: OnionMessagePath, message: OnionMessageContents<T>,
 342                 reply_path: Option<BlindedPath>
 343         ) -> Result<(), SendError> {
 344                 let (introduction_node_id, onion_msg) = create_onion_message(
 345                         &self.entropy_source, &self.node_signer, &self.secp_ctx,
 346                         path, message, reply_path
 347                 )?;
 348
 349                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 350                 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
 351                 match pending_per_peer_msgs.entry(introduction_node_id) {
 352                         hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
 353                         hash_map::Entry::Occupied(mut e) => {
 354                                 e.get_mut().push_back(onion_msg);
 355                                 Ok(())
 356                         }
 357                 }
 358         }
 359
 360         fn respond_with_onion_message<T: CustomOnionMessageContents>(
 361                 &self, response: OnionMessageContents<T>, path_id: Option<[u8; 32]>,
 362                 reply_path: Option<BlindedPath>
 363         ) {
 364                 let sender = match self.node_signer.get_node_id(Recipient::Node) {
 365                         Ok(node_id) => node_id,
 366                         Err(_) => {
 367                                 log_warn!(
 368                                         self.logger, "Unable to retrieve node id when responding to onion message with \
 369                                         path_id {:02x?}", path_id
 370                                 );
 371                                 return;
 372                         }
 373                 };
 374
 375                 let peers = self.pending_messages.lock().unwrap().keys().copied().collect();
 376
 377                 let destination = match reply_path {
 378                         Some(reply_path) => Destination::BlindedPath(reply_path),
 379                         None => {
 380                                 log_trace!(
 381                                         self.logger, "Missing reply path when responding to onion message with path_id \
 382                                         {:02x?}", path_id
 383                                 );
 384                                 return;
 385                         },
 386                 };
 387
 388                 let path = match self.message_router.find_path(sender, peers, destination) {
 389                         Ok(path) => path,
 390                         Err(()) => {
 391                                 log_trace!(
 392                                         self.logger, "Failed to find path when responding to onion message with \
 393                                         path_id {:02x?}", path_id
 394                                 );
 395                                 return;
 396                         },
 397                 };
 398
 399                 log_trace!(self.logger, "Responding to onion message with path_id {:02x?}", path_id);
 400
 401                 if let Err(e) = self.send_onion_message(path, response, None) {
 402                         log_trace!(
 403                                 self.logger, "Failed responding to onion message with path_id {:02x?}: {:?}",
 404                                 path_id, e
 405                         );
 406                         return;
 407                 }
 408         }
 409
 410         #[cfg(test)]
 411         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
 412                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 413                 let mut msgs = HashMap::new();
 414                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 415                 // swap the pending message buffers individually.
 416                 for (peer_node_id, pending_messages) in &mut *pending_msgs {
 417                         msgs.insert(*peer_node_id, core::mem::take(pending_messages));
 418                 }
 419                 msgs
 420         }
 421 }
 422
 423 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
 424         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 425         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 426         let mut total_buffered_bytes = 0;
 427         let mut peer_buffered_bytes = 0;
 428         for (pk, peer_buf) in buffer {
 429                 for om in peer_buf {
 430                         let om_len = om.serialized_length();
 431                         if pk == peer_node_id {
 432                                 peer_buffered_bytes += om_len;
 433                         }
 434                         total_buffered_bytes += om_len;
 435
 436                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 437                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 438                         {
 439                                 return true
 440                         }
 441                 }
 442         }
 443         false
 444 }
 445
 446 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 447 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 448 where
 449         ES::Target: EntropySource,
 450         NS::Target: NodeSigner,
 451         L::Target: Logger,
 452         MR::Target: MessageRouter,
 453         OMH::Target: OffersMessageHandler,
 454         CMH::Target: CustomOnionMessageHandler,
 455 {
 456         /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
 457         /// soon we'll delegate the onion message to a handler that can generate invoices or send
 458         /// payments.
 459         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
 460                 let control_tlvs_ss = match self.node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 461                         Ok(ss) => ss,
 462                         Err(e) =>  {
 463                                 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
 464                                 return
 465                         }
 466                 };
 467                 let onion_decode_ss = {
 468                         let blinding_factor = {
 469                                 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 470                                 hmac.input(control_tlvs_ss.as_ref());
 471                                 Hmac::from_engine(hmac).into_inner()
 472                         };
 473                         match self.node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 474                                 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 475                         {
 476                                 Ok(ss) => ss.secret_bytes(),
 477                                 Err(()) => {
 478                                         log_trace!(self.logger, "Failed to compute onion packet shared secret");
 479                                         return
 480                                 }
 481                         }
 482                 };
 483                 match onion_utils::decode_next_untagged_hop(
 484                         onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 485                         (control_tlvs_ss, &*self.custom_handler, &*self.logger)
 486                 ) {
 487                         Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
 488                                 message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 489                         }, None)) => {
 490                                 log_trace!(self.logger,
 491                                         "Received an onion message with path_id {:02x?} and {} reply_path",
 492                                                 path_id, if reply_path.is_some() { "a" } else { "no" });
 493
 494                                 let response = match message {
 495                                         OnionMessageContents::Offers(msg) => {
 496                                                 self.offers_handler.handle_message(msg)
 497                                                         .map(|msg| OnionMessageContents::Offers(msg))
 498                                         },
 499                                         OnionMessageContents::Custom(msg) => {
 500                                                 self.custom_handler.handle_custom_message(msg)
 501                                                         .map(|msg| OnionMessageContents::Custom(msg))
 502                                         },
 503                                 };
 504
 505                                 if let Some(response) = response {
 506                                         self.respond_with_onion_message(response, path_id, reply_path);
 507                                 }
 508                         },
 509                         Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 510                                 next_node_id, next_blinding_override
 511                         })), Some((next_hop_hmac, new_packet_bytes)))) => {
 512                                 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 513                                 // blinded hop and this onion message is destined for us. In this situation, we should keep
 514                                 // unwrapping the onion layers to get to the final payload. Since we don't have the option
 515                                 // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 516                                 // for now.
 517                                 let new_pubkey = match onion_utils::next_hop_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 518                                         Ok(pk) => pk,
 519                                         Err(e) => {
 520                                                 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
 521                                                 return
 522                                         }
 523                                 };
 524                                 let outgoing_packet = Packet {
 525                                         version: 0,
 526                                         public_key: new_pubkey,
 527                                         hop_data: new_packet_bytes,
 528                                         hmac: next_hop_hmac,
 529                                 };
 530                                 let onion_message = msgs::OnionMessage {
 531                                         blinding_point: match next_blinding_override {
 532                                                 Some(blinding_point) => blinding_point,
 533                                                 None => {
 534                                                         match onion_utils::next_hop_pubkey(
 535                                                                 &self.secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 536                                                         ) {
 537                                                                 Ok(bp) => bp,
 538                                                                 Err(e) => {
 539                                                                         log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
 540                                                                         return
 541                                                                 }
 542                                                         }
 543                                                 }
 544                                         },
 545                                         onion_routing_packet: outgoing_packet,
 546                                 };
 547
 548                                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 549                                 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
 550                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 551                                         return
 552                                 }
 553
 554                                 #[cfg(fuzzing)]
 555                                 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
 556
 557                                 match pending_per_peer_msgs.entry(next_node_id) {
 558                                         hash_map::Entry::Vacant(_) => {
 559                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 560                                                 return
 561                                         },
 562                                         hash_map::Entry::Occupied(mut e) => {
 563                                                 e.get_mut().push_back(onion_message);
 564                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 565                                         }
 566                                 };
 567                         },
 568                         Err(e) => {
 569                                 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
 570                         },
 571                         _ => {
 572                                 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 573                         },
 574                 };
 575         }
 576
 577         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 578                 if init.features.supports_onion_messages() {
 579                         let mut peers = self.pending_messages.lock().unwrap();
 580                         peers.insert(their_node_id.clone(), VecDeque::new());
 581                 }
 582                 Ok(())
 583         }
 584
 585         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 586                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 587                 pending_msgs.remove(their_node_id);
 588         }
 589
 590         fn provided_node_features(&self) -> NodeFeatures {
 591                 let mut features = NodeFeatures::empty();
 592                 features.set_onion_messages_optional();
 593                 features
 594         }
 595
 596         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
 597                 let mut features = InitFeatures::empty();
 598                 features.set_onion_messages_optional();
 599                 features
 600         }
 601 }
 602
 603 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageProvider
 604 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 605 where
 606         ES::Target: EntropySource,
 607         NS::Target: NodeSigner,
 608         L::Target: Logger,
 609         MR::Target: MessageRouter,
 610         OMH::Target: OffersMessageHandler,
 611         CMH::Target: CustomOnionMessageHandler,
 612 {
 613         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
 614                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 615                 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
 616                         return msgs.pop_front()
 617                 }
 618                 None
 619         }
 620 }
 621
 622 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
 623 // produces
 624 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 625 /// [`SimpleArcPeerManager`]. See their docs for more details.
 626 ///
 627 /// This is not exported to bindings users as `Arc`s don't make sense in bindings.
 628 ///
 629 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 630 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
 631 pub type SimpleArcOnionMessenger<L> = OnionMessenger<
 632         Arc<KeysManager>,
 633         Arc<KeysManager>,
 634         Arc<L>,
 635         Arc<DefaultMessageRouter>,
 636         IgnoringMessageHandler,
 637         IgnoringMessageHandler
 638 >;
 639
 640 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 641 /// [`SimpleRefPeerManager`]. See their docs for more details.
 642 ///
 643 /// This is not exported to bindings users as general type aliases don't make sense in bindings.
 644 ///
 645 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 646 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
 647 pub type SimpleRefOnionMessenger<'a, 'b, 'c, L> = OnionMessenger<
 648         &'a KeysManager,
 649         &'a KeysManager,
 650         &'b L,
 651         &'c DefaultMessageRouter,
 652         IgnoringMessageHandler,
 653         IgnoringMessageHandler
 654 >;
 655
 656 /// Construct onion packet payloads and keys for sending an onion message along the given
 657 /// `unblinded_path` to the given `destination`.
 658 fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
 659         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
 660         message: OnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 661 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 662         let num_hops = unblinded_path.len() + destination.num_hops();
 663         let mut payloads = Vec::with_capacity(num_hops);
 664         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 665
 666         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
 667                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 668                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 669         let num_unblinded_hops = num_hops - num_blinded_hops;
 670
 671         let mut unblinded_path_idx = 0;
 672         let mut blinded_path_idx = 0;
 673         let mut prev_control_tlvs_ss = None;
 674         let mut final_control_tlvs = None;
 675         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
 676                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
 677                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 678                                 if let Some(ss) = prev_control_tlvs_ss.take() {
 679                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
 680                                                 ForwardTlvs {
 681                                                         next_node_id: unblinded_pk_opt.unwrap(),
 682                                                         next_blinding_override: None,
 683                                                 }
 684                                         )), ss));
 685                                 }
 686                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 687                                 unblinded_path_idx += 1;
 688                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
 689                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
 690                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 691                                                 next_node_id: intro_node_id,
 692                                                 next_blinding_override: Some(blinding_pt),
 693                                         })), control_tlvs_ss));
 694                                 }
 695                         }
 696                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
 697                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
 698                                         control_tlvs_ss));
 699                                 blinded_path_idx += 1;
 700                         } else if let Some(encrypted_payload) = enc_payload_opt {
 701                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
 702                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 703                         }
 704
 705                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
 706                         onion_packet_keys.push(onion_utils::OnionKeys {
 707                                 #[cfg(test)]
 708                                 shared_secret: onion_packet_ss,
 709                                 #[cfg(test)]
 710                                 blinding_factor: [0; 32],
 711                                 ephemeral_pubkey,
 712                                 rho,
 713                                 mu,
 714                         });
 715                 }
 716         )?;
 717
 718         if let Some(control_tlvs) = final_control_tlvs {
 719                 payloads.push((Payload::Receive {
 720                         control_tlvs,
 721                         reply_path: reply_path.take(),
 722                         message,
 723                 }, prev_control_tlvs_ss.unwrap()));
 724         } else {
 725                 payloads.push((Payload::Receive {
 726                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
 727                         reply_path: reply_path.take(),
 728                         message,
 729                 }, prev_control_tlvs_ss.unwrap()));
 730         }
 731
 732         Ok((payloads, onion_packet_keys))
 733 }
 734
 735 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
 736 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, ()> {
 737         // Spec rationale:
 738         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
 739         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
 740         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
 741         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
 742         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
 743                 SMALL_PACKET_HOP_DATA_LEN
 744         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
 745                 BIG_PACKET_HOP_DATA_LEN
 746         } else { return Err(()) };
 747
 748         onion_utils::construct_onion_message_packet::<_, _>(
 749                 payloads, onion_keys, prng_seed, hop_data_len)
 750 }