_ 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::ln::features::{InitFeatures, NodeFeatures};
  23 use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler};
  24 use crate::ln::onion_utils;
  25 use crate::ln::peer_handler::IgnoringMessageHandler;
  26 pub use super::packet::{CustomOnionMessageContents, ParsedOnionMessageContents};
  27 use super::offers::OffersMessageHandler;
  28 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  29 use crate::util::logger::Logger;
  30 use crate::util::ser::Writeable;
  31
  32 use core::fmt;
  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 [`OnionMessage`]s.
  39 ///
  40 /// # Handling Messages
  41 ///
  42 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
  43 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
  44 /// available handlers are:
  45 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
  46 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
  47 ///
  48 /// # Sending Messages
  49 ///
  50 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
  51 /// a message, the matched handler may return a response message which `OnionMessenger` will send
  52 /// on its behalf.
  53 ///
  54 /// # Example
  55 ///
  56 /// ```
  57 /// # extern crate bitcoin;
  58 /// # use bitcoin::hashes::_export::_core::time::Duration;
  59 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
  60 /// # use lightning::blinded_path::BlindedPath;
  61 /// # use lightning::sign::KeysManager;
  62 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  63 /// # use lightning::onion_message::{CustomOnionMessageContents, Destination, MessageRouter, ParsedOnionMessageContents, OnionMessagePath, OnionMessenger};
  64 /// # use lightning::util::logger::{Logger, Record};
  65 /// # use lightning::util::ser::{Writeable, Writer};
  66 /// # use lightning::io;
  67 /// # use std::sync::Arc;
  68 /// # struct FakeLogger;
  69 /// # impl Logger for FakeLogger {
  70 /// #     fn log(&self, record: &Record) { unimplemented!() }
  71 /// # }
  72 /// # struct FakeMessageRouter {}
  73 /// # impl MessageRouter for FakeMessageRouter {
  74 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  75 /// #         unimplemented!()
  76 /// #     }
  77 /// # }
  78 /// # let seed = [42u8; 32];
  79 /// # let time = Duration::from_secs(123456);
  80 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
  81 /// # let logger = Arc::new(FakeLogger {});
  82 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  83 /// # let secp_ctx = Secp256k1::new();
  84 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  85 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
  86 /// # let destination_node_id = hop_node_id1;
  87 /// # let message_router = Arc::new(FakeMessageRouter {});
  88 /// # let custom_message_handler = IgnoringMessageHandler {};
  89 /// # let offers_message_handler = IgnoringMessageHandler {};
  90 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
  91 /// // ChannelManager.
  92 /// let onion_messenger = OnionMessenger::new(
  93 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
  94 ///     &custom_message_handler
  95 /// );
  96 ///
  97 /// # struct YourCustomMessage {}
  98 /// impl Writeable for YourCustomMessage {
  99 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 100 ///             # Ok(())
 101 ///             // Write your custom onion message to `w`
 102 ///     }
 103 /// }
 104 /// impl CustomOnionMessageContents for YourCustomMessage {
 105 ///     fn tlv_type(&self) -> u64 {
 106 ///             # let your_custom_message_type = 42;
 107 ///             your_custom_message_type
 108 ///     }
 109 /// }
 110 /// // Send a custom onion message to a node id.
 111 /// let path = OnionMessagePath {
 112 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 113 ///     destination: Destination::Node(destination_node_id),
 114 /// };
 115 /// let reply_path = None;
 116 /// # let your_custom_message = YourCustomMessage {};
 117 /// let message = ParsedOnionMessageContents::Custom(your_custom_message);
 118 /// onion_messenger.send_onion_message(path, message, reply_path);
 119 ///
 120 /// // Create a blinded path to yourself, for someone to send an onion message to.
 121 /// # let your_node_id = hop_node_id1;
 122 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 123 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 124 ///
 125 /// // Send a custom onion message to a blinded path.
 126 /// let path = OnionMessagePath {
 127 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 128 ///     destination: Destination::BlindedPath(blinded_path),
 129 /// };
 130 /// let reply_path = None;
 131 /// # let your_custom_message = YourCustomMessage {};
 132 /// let message = ParsedOnionMessageContents::Custom(your_custom_message);
 133 /// onion_messenger.send_onion_message(path, message, reply_path);
 134 /// ```
 135 ///
 136 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 137 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 138 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 139 where
 140         ES::Target: EntropySource,
 141         NS::Target: NodeSigner,
 142         L::Target: Logger,
 143         MR::Target: MessageRouter,
 144         OMH::Target: OffersMessageHandler,
 145         CMH:: Target: CustomOnionMessageHandler,
 146 {
 147         entropy_source: ES,
 148         node_signer: NS,
 149         logger: L,
 150         pending_messages: Mutex<HashMap<PublicKey, VecDeque<OnionMessage>>>,
 151         secp_ctx: Secp256k1<secp256k1::All>,
 152         message_router: MR,
 153         offers_handler: OMH,
 154         custom_handler: CMH,
 155 }
 156
 157 /// A trait defining behavior for routing an [`OnionMessage`].
 158 pub trait MessageRouter {
 159         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 160         fn find_path(
 161                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 162         ) -> Result<OnionMessagePath, ()>;
 163 }
 164
 165 /// A [`MessageRouter`] that always fails.
 166 pub struct DefaultMessageRouter;
 167
 168 impl MessageRouter for DefaultMessageRouter {
 169         fn find_path(
 170                 &self, _sender: PublicKey, _peers: Vec<PublicKey>, _destination: Destination
 171         ) -> Result<OnionMessagePath, ()> {
 172                 Err(())
 173         }
 174 }
 175
 176 /// A path for sending an [`OnionMessage`].
 177 #[derive(Clone)]
 178 pub struct OnionMessagePath {
 179         /// Nodes on the path between the sender and the destination.
 180         pub intermediate_nodes: Vec<PublicKey>,
 181
 182         /// The recipient of the message.
 183         pub destination: Destination,
 184 }
 185
 186 /// The destination of an onion message.
 187 #[derive(Clone)]
 188 pub enum Destination {
 189         /// We're sending this onion message to a node.
 190         Node(PublicKey),
 191         /// We're sending this onion message to a blinded path.
 192         BlindedPath(BlindedPath),
 193 }
 194
 195 impl Destination {
 196         pub(super) fn num_hops(&self) -> usize {
 197                 match self {
 198                         Destination::Node(_) => 1,
 199                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 200                 }
 201         }
 202 }
 203
 204 /// Errors that may occur when [sending an onion message].
 205 ///
 206 /// [sending an onion message]: OnionMessenger::send_onion_message
 207 #[derive(Debug, PartialEq, Eq)]
 208 pub enum SendError {
 209         /// Errored computing onion message packet keys.
 210         Secp256k1(secp256k1::Error),
 211         /// Because implementations such as Eclair will drop onion messages where the message packet
 212         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 213         TooBigPacket,
 214         /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two
 215         /// blinded hops.
 216         TooFewBlindedHops,
 217         /// Our next-hop peer was offline or does not support onion message forwarding.
 218         InvalidFirstHop,
 219         /// Onion message contents must have a TLV type >= 64.
 220         InvalidMessage,
 221         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 222         BufferFull,
 223         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 224         ///
 225         /// [`NodeSigner`]: crate::sign::NodeSigner
 226         GetNodeIdFailed,
 227         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 228         /// advance the blinded path to make the second hop the new introduction node. Either
 229         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 230         /// new blinding point, or we were attempting to send to ourselves.
 231         BlindedPathAdvanceFailed,
 232 }
 233
 234 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 235 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 236 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 237 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 238 /// message types.
 239 ///
 240 /// See [`OnionMessenger`] for example usage.
 241 ///
 242 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 243 /// [`CustomMessage`]: Self::CustomMessage
 244 pub trait CustomOnionMessageHandler {
 245         /// The message known to the handler. To support multiple message types, you may want to make this
 246         /// an enum with a variant for each supported message.
 247         type CustomMessage: CustomOnionMessageContents;
 248
 249         /// Called with the custom message that was received, returning a response to send, if any.
 250         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 251
 252         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 253         /// message type is unknown.
 254         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 255 }
 256
 257 /// A processed incoming onion message, containing either a Forward (another onion message)
 258 /// or a Receive payload with decrypted contents.
 259 pub enum PeeledOnion<CM: CustomOnionMessageContents> {
 260         /// Forwarded onion, with the next node id and a new onion
 261         Forward(PublicKey, OnionMessage),
 262         /// Received onion message, with decrypted contents, path_id, and reply path
 263         Receive(ParsedOnionMessageContents<CM>, Option<[u8; 32]>, Option<BlindedPath>)
 264 }
 265
 266 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 267 /// `path`.
 268 ///
 269 /// Returns both the node id of the peer to send the message to and the message itself.
 270 pub fn create_onion_message<ES: Deref, NS: Deref, T: CustomOnionMessageContents>(
 271         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 272         path: OnionMessagePath, contents: ParsedOnionMessageContents<T>,
 273         reply_path: Option<BlindedPath>,
 274 ) -> Result<(PublicKey, OnionMessage), SendError>
 275 where
 276         ES::Target: EntropySource,
 277         NS::Target: NodeSigner,
 278 {
 279         let OnionMessagePath { intermediate_nodes, mut destination } = path;
 280         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 281                 if blinded_hops.len() < 2 {
 282                         return Err(SendError::TooFewBlindedHops);
 283                 }
 284         }
 285
 286         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 287
 288         // If we are sending straight to a blinded path and we are the introduction node, we need to
 289         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 290         if intermediate_nodes.len() == 0 {
 291                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 292                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 293                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 294                         if blinded_path.introduction_node_id == our_node_id {
 295                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 296                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 297                         }
 298                 }
 299         }
 300
 301         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 302         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 303         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 304                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 305         } else {
 306                 match destination {
 307                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 308                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 309                                 (introduction_node_id, blinding_point),
 310                 }
 311         };
 312         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 313                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret)
 314                 .map_err(|e| SendError::Secp256k1(e))?;
 315
 316         let prng_seed = entropy_source.get_secure_random_bytes();
 317         let onion_routing_packet = construct_onion_message_packet(
 318                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 319
 320         Ok((first_node_id, OnionMessage {
 321                 blinding_point,
 322                 onion_routing_packet
 323         }))
 324 }
 325
 326 /// Decode one layer of an incoming onion message
 327 /// Returns either a Forward (another onion message), or Receive (decrypted content)
 328 pub fn peel_onion<NS: Deref, L: Deref, CMH: Deref>(
 329         node_signer: NS, secp_ctx: &Secp256k1<secp256k1::All>, logger: L, custom_handler: CMH,
 330         msg: &OnionMessage,
 331 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 332 where
 333         NS::Target: NodeSigner,
 334         L::Target: Logger,
 335         CMH::Target: CustomOnionMessageHandler,
 336 {
 337         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 338                 Ok(ss) => ss,
 339                 Err(e) =>  {
 340                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 341                         return Err(());
 342                 }
 343         };
 344         let onion_decode_ss = {
 345                 let blinding_factor = {
 346                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 347                         hmac.input(control_tlvs_ss.as_ref());
 348                         Hmac::from_engine(hmac).into_inner()
 349                 };
 350                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 351                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 352                 {
 353                         Ok(ss) => ss.secret_bytes(),
 354                         Err(()) => {
 355                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 356                                 return Err(());
 357                         }
 358                 }
 359         };
 360         match onion_utils::decode_next_untagged_hop(
 361                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 362                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 363         ) {
 364                 Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
 365                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 366                 }, None)) => {
 367                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 368                 },
 369                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 370                         next_node_id, next_blinding_override
 371                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 372                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 373                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 374                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 375                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 376                         // for now.
 377                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 378                                 Ok(pk) => pk,
 379                                 Err(e) => {
 380                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 381                                         return Err(())
 382                                 }
 383                         };
 384                         let outgoing_packet = Packet {
 385                                 version: 0,
 386                                 public_key: new_pubkey,
 387                                 hop_data: new_packet_bytes,
 388                                 hmac: next_hop_hmac,
 389                         };
 390                         let onion_message = OnionMessage {
 391                                 blinding_point: match next_blinding_override {
 392                                         Some(blinding_point) => blinding_point,
 393                                         None => {
 394                                                 match onion_utils::next_hop_pubkey(
 395                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 396                                                 ) {
 397                                                         Ok(bp) => bp,
 398                                                         Err(e) => {
 399                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 400                                                                 return Err(())
 401                                                         }
 402                                                 }
 403                                         }
 404                                 },
 405                                 onion_routing_packet: outgoing_packet,
 406                         };
 407
 408                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 409                 },
 410                 Err(e) => {
 411                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 412                         Err(())
 413                 },
 414                 _ => {
 415                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 416                         Err(())
 417                 },
 418         }
 419 }
 420
 421 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 422 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 423 where
 424         ES::Target: EntropySource,
 425         NS::Target: NodeSigner,
 426         L::Target: Logger,
 427         MR::Target: MessageRouter,
 428         OMH::Target: OffersMessageHandler,
 429         CMH::Target: CustomOnionMessageHandler,
 430 {
 431         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 432         /// their respective handlers.
 433         pub fn new(
 434                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 435                 custom_handler: CMH
 436         ) -> Self {
 437                 let mut secp_ctx = Secp256k1::new();
 438                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 439                 OnionMessenger {
 440                         entropy_source,
 441                         node_signer,
 442                         pending_messages: Mutex::new(HashMap::new()),
 443                         secp_ctx,
 444                         logger,
 445                         message_router,
 446                         offers_handler,
 447                         custom_handler,
 448                 }
 449         }
 450
 451         /// Sends an [`OnionMessage`] with the given `contents` for sending to the destination of
 452         /// `path`.
 453         ///
 454         /// See [`OnionMessenger`] for example usage.
 455         pub fn send_onion_message<T: CustomOnionMessageContents>(
 456                 &self, path: OnionMessagePath, contents: ParsedOnionMessageContents<T>,
 457                 reply_path: Option<BlindedPath>
 458         ) -> Result<(), SendError> {
 459                 let (first_node_id, onion_msg) = create_onion_message(
 460                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
 461                 )?;
 462
 463                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 464                 if outbound_buffer_full(&first_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
 465                 match pending_per_peer_msgs.entry(first_node_id) {
 466                         hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
 467                         hash_map::Entry::Occupied(mut e) => {
 468                                 e.get_mut().push_back(onion_msg);
 469                                 Ok(())
 470                         }
 471                 }
 472         }
 473
 474         fn find_path_and_enqueue_onion_message<T: CustomOnionMessageContents>(
 475                 &self, contents: ParsedOnionMessageContents<T>, destination: Destination,
 476                 log_suffix: fmt::Arguments
 477         ) {
 478                 let sender = match self.node_signer.get_node_id(Recipient::Node) {
 479                         Ok(node_id) => node_id,
 480                         Err(_) => {
 481                                 log_warn!(self.logger, "Unable to retrieve node id {}", log_suffix);
 482                                 return;
 483                         }
 484                 };
 485
 486                 let peers = self.pending_messages.lock().unwrap().keys().copied().collect();
 487                 let path = match self.message_router.find_path(sender, peers, destination) {
 488                         Ok(path) => path,
 489                         Err(()) => {
 490                                 log_trace!(self.logger, "Failed to find path {}", log_suffix);
 491                                 return;
 492                         },
 493                 };
 494
 495                 log_trace!(self.logger, "Sending onion message {}", log_suffix);
 496
 497                 if let Err(e) = self.send_onion_message(path, contents, None) {
 498                         log_trace!(self.logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 499                         return;
 500                 }
 501         }
 502
 503         #[cfg(test)]
 504         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 505                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 506                 let mut msgs = HashMap::new();
 507                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 508                 // swap the pending message buffers individually.
 509                 for (peer_node_id, pending_messages) in &mut *pending_msgs {
 510                         msgs.insert(*peer_node_id, core::mem::take(pending_messages));
 511                 }
 512                 msgs
 513         }
 514 }
 515
 516 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<OnionMessage>>) -> bool {
 517         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 518         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 519         let mut total_buffered_bytes = 0;
 520         let mut peer_buffered_bytes = 0;
 521         for (pk, peer_buf) in buffer {
 522                 for om in peer_buf {
 523                         let om_len = om.serialized_length();
 524                         if pk == peer_node_id {
 525                                 peer_buffered_bytes += om_len;
 526                         }
 527                         total_buffered_bytes += om_len;
 528
 529                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 530                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 531                         {
 532                                 return true
 533                         }
 534                 }
 535         }
 536         false
 537 }
 538
 539 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 540 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 541 where
 542         ES::Target: EntropySource,
 543         NS::Target: NodeSigner,
 544         L::Target: Logger,
 545         MR::Target: MessageRouter,
 546         OMH::Target: OffersMessageHandler,
 547         CMH::Target: CustomOnionMessageHandler,
 548 {
 549         /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
 550         /// soon we'll delegate the onion message to a handler that can generate invoices or send
 551         /// payments.
 552         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
 553                 match peel_onion(
 554                         &*self.node_signer, &self.secp_ctx, &*self.logger, &*self.custom_handler, msg
 555                 ) {
 556                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 557                                 log_trace!(self.logger,
 558                                         "Received an onion message with path_id {:02x?} and {} reply_path",
 559                                                 path_id, if reply_path.is_some() { "a" } else { "no" });
 560                                 let response = match message {
 561                                         ParsedOnionMessageContents::Offers(msg) => {
 562                                                 self.offers_handler.handle_message(msg)
 563                                                         .map(|msg| ParsedOnionMessageContents::Offers(msg))
 564                                         },
 565                                         ParsedOnionMessageContents::Custom(msg) => {
 566                                                 self.custom_handler.handle_custom_message(msg)
 567                                                         .map(|msg| ParsedOnionMessageContents::Custom(msg))
 568                                         },
 569                                 };
 570                                 if let Some(response) = response {
 571                                         match reply_path {
 572                                                 Some(reply_path) => {
 573                                                         self.find_path_and_enqueue_onion_message(
 574                                                                 response, Destination::BlindedPath(reply_path), format_args!(
 575                                                                         "when responding to onion message with path_id {:02x?}", path_id
 576                                                                 )
 577                                                         );
 578                                                 },
 579                                                 None => {
 580                                                         log_trace!(
 581                                                                 self.logger,
 582                                                                 "Missing reply path when responding to onion message with path_id {:02x?}",
 583                                                                 path_id
 584                                                         );
 585                                                 },
 586                                         }
 587                                 }
 588                         },
 589                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 590                                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 591                                 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
 592                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 593                                         return
 594                                 }
 595
 596                                 #[cfg(fuzzing)]
 597                                 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
 598
 599                                 match pending_per_peer_msgs.entry(next_node_id) {
 600                                         hash_map::Entry::Vacant(_) => {
 601                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 602                                                 return
 603                                         },
 604                                         hash_map::Entry::Occupied(mut e) => {
 605                                                 e.get_mut().push_back(onion_message);
 606                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 607                                         }
 608                                 }
 609                         },
 610                         Err(e) => {
 611                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
 612                         }
 613                 }
 614         }
 615
 616         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 617                 if init.features.supports_onion_messages() {
 618                         let mut peers = self.pending_messages.lock().unwrap();
 619                         peers.insert(their_node_id.clone(), VecDeque::new());
 620                 }
 621                 Ok(())
 622         }
 623
 624         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 625                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 626                 pending_msgs.remove(their_node_id);
 627         }
 628
 629         fn provided_node_features(&self) -> NodeFeatures {
 630                 let mut features = NodeFeatures::empty();
 631                 features.set_onion_messages_optional();
 632                 features
 633         }
 634
 635         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
 636                 let mut features = InitFeatures::empty();
 637                 features.set_onion_messages_optional();
 638                 features
 639         }
 640
 641         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
 642                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 643                 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
 644                         return msgs.pop_front()
 645                 }
 646                 None
 647         }
 648 }
 649
 650 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
 651 // produces
 652 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 653 /// [`SimpleArcPeerManager`]. See their docs for more details.
 654 ///
 655 /// This is not exported to bindings users as `Arc`s don't make sense in bindings.
 656 ///
 657 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 658 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
 659 pub type SimpleArcOnionMessenger<L> = OnionMessenger<
 660         Arc<KeysManager>,
 661         Arc<KeysManager>,
 662         Arc<L>,
 663         Arc<DefaultMessageRouter>,
 664         IgnoringMessageHandler,
 665         IgnoringMessageHandler
 666 >;
 667
 668 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 669 /// [`SimpleRefPeerManager`]. See their docs for more details.
 670 ///
 671 /// This is not exported to bindings users as general type aliases don't make sense in bindings.
 672 ///
 673 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 674 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
 675 pub type SimpleRefOnionMessenger<'a, 'b, 'c, L> = OnionMessenger<
 676         &'a KeysManager,
 677         &'a KeysManager,
 678         &'b L,
 679         &'c DefaultMessageRouter,
 680         IgnoringMessageHandler,
 681         IgnoringMessageHandler
 682 >;
 683
 684 /// Construct onion packet payloads and keys for sending an onion message along the given
 685 /// `unblinded_path` to the given `destination`.
 686 fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
 687         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
 688         message: ParsedOnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 689 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 690         let num_hops = unblinded_path.len() + destination.num_hops();
 691         let mut payloads = Vec::with_capacity(num_hops);
 692         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 693
 694         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
 695                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 696                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 697         let num_unblinded_hops = num_hops - num_blinded_hops;
 698
 699         let mut unblinded_path_idx = 0;
 700         let mut blinded_path_idx = 0;
 701         let mut prev_control_tlvs_ss = None;
 702         let mut final_control_tlvs = None;
 703         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
 704                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
 705                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 706                                 if let Some(ss) = prev_control_tlvs_ss.take() {
 707                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
 708                                                 ForwardTlvs {
 709                                                         next_node_id: unblinded_pk_opt.unwrap(),
 710                                                         next_blinding_override: None,
 711                                                 }
 712                                         )), ss));
 713                                 }
 714                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 715                                 unblinded_path_idx += 1;
 716                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
 717                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
 718                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 719                                                 next_node_id: intro_node_id,
 720                                                 next_blinding_override: Some(blinding_pt),
 721                                         })), control_tlvs_ss));
 722                                 }
 723                         }
 724                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
 725                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
 726                                         control_tlvs_ss));
 727                                 blinded_path_idx += 1;
 728                         } else if let Some(encrypted_payload) = enc_payload_opt {
 729                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
 730                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 731                         }
 732
 733                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
 734                         onion_packet_keys.push(onion_utils::OnionKeys {
 735                                 #[cfg(test)]
 736                                 shared_secret: onion_packet_ss,
 737                                 #[cfg(test)]
 738                                 blinding_factor: [0; 32],
 739                                 ephemeral_pubkey,
 740                                 rho,
 741                                 mu,
 742                         });
 743                 }
 744         )?;
 745
 746         if let Some(control_tlvs) = final_control_tlvs {
 747                 payloads.push((Payload::Receive {
 748                         control_tlvs,
 749                         reply_path: reply_path.take(),
 750                         message,
 751                 }, prev_control_tlvs_ss.unwrap()));
 752         } else {
 753                 payloads.push((Payload::Receive {
 754                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
 755                         reply_path: reply_path.take(),
 756                         message,
 757                 }, prev_control_tlvs_ss.unwrap()));
 758         }
 759
 760         Ok((payloads, onion_packet_keys))
 761 }
 762
 763 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
 764 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, ()> {
 765         // Spec rationale:
 766         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
 767         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
 768         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
 769         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
 770         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
 771                 SMALL_PACKET_HOP_DATA_LEN
 772         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
 773                 BIG_PACKET_HOP_DATA_LEN
 774         } else { return Err(()) };
 775
 776         onion_utils::construct_onion_message_packet::<_, _>(
 777                 payloads, onion_keys, prng_seed, hop_data_len)
 778 }