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