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