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