git.bitcoin.ninja 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::channelmanager::{SimpleArcChannelManager, SimpleRefChannelManager};
  23 use crate::ln::features::{InitFeatures, NodeFeatures};
  24 use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler};
  25 use crate::ln::onion_utils;
  26 use crate::ln::peer_handler::IgnoringMessageHandler;
  27 pub use super::packet::OnionMessageContents;
  28 use super::packet::ParsedOnionMessageContents;
  29 use super::offers::OffersMessageHandler;
  30 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  31 use crate::util::logger::Logger;
  32 use crate::util::ser::Writeable;
  33
  34 use core::fmt;
  35 use core::ops::Deref;
  36 use crate::io;
  37 use crate::sync::{Arc, Mutex};
  38 use crate::prelude::*;
  39
  40 /// A sender, receiver and forwarder of [`OnionMessage`]s.
  41 ///
  42 /// # Handling Messages
  43 ///
  44 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
  45 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
  46 /// available handlers are:
  47 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
  48 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
  49 ///
  50 /// # Sending Messages
  51 ///
  52 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
  53 /// a message, the matched handler may return a response message which `OnionMessenger` will send
  54 /// on its behalf.
  55 ///
  56 /// # Example
  57 ///
  58 /// ```
  59 /// # extern crate bitcoin;
  60 /// # use bitcoin::hashes::_export::_core::time::Duration;
  61 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
  62 /// # use lightning::blinded_path::BlindedPath;
  63 /// # use lightning::sign::KeysManager;
  64 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  65 /// # use lightning::onion_message::{OnionMessageContents, Destination, MessageRouter, OnionMessagePath, OnionMessenger};
  66 /// # use lightning::util::logger::{Logger, Record};
  67 /// # use lightning::util::ser::{Writeable, Writer};
  68 /// # use lightning::io;
  69 /// # use std::sync::Arc;
  70 /// # struct FakeLogger;
  71 /// # impl Logger for FakeLogger {
  72 /// #     fn log(&self, record: &Record) { unimplemented!() }
  73 /// # }
  74 /// # struct FakeMessageRouter {}
  75 /// # impl MessageRouter for FakeMessageRouter {
  76 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  77 /// #         unimplemented!()
  78 /// #     }
  79 /// # }
  80 /// # let seed = [42u8; 32];
  81 /// # let time = Duration::from_secs(123456);
  82 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
  83 /// # let logger = Arc::new(FakeLogger {});
  84 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  85 /// # let secp_ctx = Secp256k1::new();
  86 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  87 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
  88 /// # let destination_node_id = hop_node_id1;
  89 /// # let message_router = Arc::new(FakeMessageRouter {});
  90 /// # let custom_message_handler = IgnoringMessageHandler {};
  91 /// # let offers_message_handler = IgnoringMessageHandler {};
  92 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
  93 /// // ChannelManager.
  94 /// let onion_messenger = OnionMessenger::new(
  95 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
  96 ///     &custom_message_handler
  97 /// );
  98 ///
  99 /// # struct YourCustomMessage {}
 100 /// impl Writeable for YourCustomMessage {
 101 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 102 ///             # Ok(())
 103 ///             // Write your custom onion message to `w`
 104 ///     }
 105 /// }
 106 /// impl OnionMessageContents for YourCustomMessage {
 107 ///     fn tlv_type(&self) -> u64 {
 108 ///             # let your_custom_message_type = 42;
 109 ///             your_custom_message_type
 110 ///     }
 111 /// }
 112 /// // Send a custom onion message to a node id.
 113 /// let path = OnionMessagePath {
 114 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 115 ///     destination: Destination::Node(destination_node_id),
 116 /// };
 117 /// let reply_path = None;
 118 /// # let message = YourCustomMessage {};
 119 /// onion_messenger.send_onion_message(path, message, reply_path);
 120 ///
 121 /// // Create a blinded path to yourself, for someone to send an onion message to.
 122 /// # let your_node_id = hop_node_id1;
 123 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 124 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 125 ///
 126 /// // Send a custom onion message to a blinded path.
 127 /// let path = OnionMessagePath {
 128 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 129 ///     destination: Destination::BlindedPath(blinded_path),
 130 /// };
 131 /// let reply_path = None;
 132 /// # let message = YourCustomMessage {};
 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 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 158 ///
 159 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 160 /// enqueued for sending.
 161 pub struct PendingOnionMessage<T: OnionMessageContents> {
 162         /// The message contents to send in an [`OnionMessage`].
 163         pub contents: T,
 164
 165         /// The destination of the message.
 166         pub destination: Destination,
 167
 168         /// A reply path to include in the [`OnionMessage`] for a response.
 169         pub reply_path: Option<BlindedPath>,
 170 }
 171
 172 /// A trait defining behavior for routing an [`OnionMessage`].
 173 pub trait MessageRouter {
 174         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 175         fn find_path(
 176                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 177         ) -> Result<OnionMessagePath, ()>;
 178 }
 179
 180 /// A [`MessageRouter`] that always fails.
 181 pub struct DefaultMessageRouter;
 182
 183 impl MessageRouter for DefaultMessageRouter {
 184         fn find_path(
 185                 &self, _sender: PublicKey, _peers: Vec<PublicKey>, _destination: Destination
 186         ) -> Result<OnionMessagePath, ()> {
 187                 Err(())
 188         }
 189 }
 190
 191 /// A path for sending an [`OnionMessage`].
 192 #[derive(Clone)]
 193 pub struct OnionMessagePath {
 194         /// Nodes on the path between the sender and the destination.
 195         pub intermediate_nodes: Vec<PublicKey>,
 196
 197         /// The recipient of the message.
 198         pub destination: Destination,
 199 }
 200
 201 /// The destination of an onion message.
 202 #[derive(Clone)]
 203 pub enum Destination {
 204         /// We're sending this onion message to a node.
 205         Node(PublicKey),
 206         /// We're sending this onion message to a blinded path.
 207         BlindedPath(BlindedPath),
 208 }
 209
 210 impl Destination {
 211         pub(super) fn num_hops(&self) -> usize {
 212                 match self {
 213                         Destination::Node(_) => 1,
 214                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 215                 }
 216         }
 217 }
 218
 219 /// Errors that may occur when [sending an onion message].
 220 ///
 221 /// [sending an onion message]: OnionMessenger::send_onion_message
 222 #[derive(Debug, PartialEq, Eq)]
 223 pub enum SendError {
 224         /// Errored computing onion message packet keys.
 225         Secp256k1(secp256k1::Error),
 226         /// Because implementations such as Eclair will drop onion messages where the message packet
 227         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 228         TooBigPacket,
 229         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 230         /// hops.
 231         TooFewBlindedHops,
 232         /// Our next-hop peer was offline or does not support onion message forwarding.
 233         InvalidFirstHop,
 234         /// Onion message contents must have a TLV type >= 64.
 235         InvalidMessage,
 236         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 237         BufferFull,
 238         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 239         ///
 240         /// [`NodeSigner`]: crate::sign::NodeSigner
 241         GetNodeIdFailed,
 242         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 243         /// advance the blinded path to make the second hop the new introduction node. Either
 244         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 245         /// new blinding point, or we were attempting to send to ourselves.
 246         BlindedPathAdvanceFailed,
 247 }
 248
 249 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 250 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 251 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 252 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 253 /// message types.
 254 ///
 255 /// See [`OnionMessenger`] for example usage.
 256 ///
 257 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 258 /// [`CustomMessage`]: Self::CustomMessage
 259 pub trait CustomOnionMessageHandler {
 260         /// The message known to the handler. To support multiple message types, you may want to make this
 261         /// an enum with a variant for each supported message.
 262         type CustomMessage: OnionMessageContents;
 263
 264         /// Called with the custom message that was received, returning a response to send, if any.
 265         ///
 266         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 267         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 268
 269         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 270         /// message type is unknown.
 271         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 272
 273         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 274         ///
 275         /// Typically, this is used for messages initiating a message flow rather than in response to
 276         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 277         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 278 }
 279
 280 /// A processed incoming onion message, containing either a Forward (another onion message)
 281 /// or a Receive payload with decrypted contents.
 282 pub enum PeeledOnion<T: OnionMessageContents> {
 283         /// Forwarded onion, with the next node id and a new onion
 284         Forward(PublicKey, OnionMessage),
 285         /// Received onion message, with decrypted contents, path_id, and reply path
 286         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 287 }
 288
 289 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 290 /// `path`.
 291 ///
 292 /// Returns both the node id of the peer to send the message to and the message itself.
 293 pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
 294         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 295         path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 296 ) -> Result<(PublicKey, OnionMessage), SendError>
 297 where
 298         ES::Target: EntropySource,
 299         NS::Target: NodeSigner,
 300 {
 301         let OnionMessagePath { intermediate_nodes, mut destination } = path;
 302         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 303                 if blinded_hops.is_empty() {
 304                         return Err(SendError::TooFewBlindedHops);
 305                 }
 306         }
 307
 308         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 309
 310         // If we are sending straight to a blinded path and we are the introduction node, we need to
 311         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 312         if intermediate_nodes.len() == 0 {
 313                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 314                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 315                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 316                         if blinded_path.introduction_node_id == our_node_id {
 317                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 318                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 319                         }
 320                 }
 321         }
 322
 323         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 324         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 325         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 326                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 327         } else {
 328                 match destination {
 329                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 330                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 331                                 (introduction_node_id, blinding_point),
 332                 }
 333         };
 334         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 335                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret)
 336                 .map_err(|e| SendError::Secp256k1(e))?;
 337
 338         let prng_seed = entropy_source.get_secure_random_bytes();
 339         let onion_routing_packet = construct_onion_message_packet(
 340                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 341
 342         Ok((first_node_id, OnionMessage {
 343                 blinding_point,
 344                 onion_routing_packet
 345         }))
 346 }
 347
 348 /// Decode one layer of an incoming [`OnionMessage`].
 349 ///
 350 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 351 /// receiver.
 352 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 353         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 354         custom_handler: CMH,
 355 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 356 where
 357         NS::Target: NodeSigner,
 358         L::Target: Logger,
 359         CMH::Target: CustomOnionMessageHandler,
 360 {
 361         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 362                 Ok(ss) => ss,
 363                 Err(e) =>  {
 364                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 365                         return Err(());
 366                 }
 367         };
 368         let onion_decode_ss = {
 369                 let blinding_factor = {
 370                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 371                         hmac.input(control_tlvs_ss.as_ref());
 372                         Hmac::from_engine(hmac).into_inner()
 373                 };
 374                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 375                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 376                 {
 377                         Ok(ss) => ss.secret_bytes(),
 378                         Err(()) => {
 379                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 380                                 return Err(());
 381                         }
 382                 }
 383         };
 384         match onion_utils::decode_next_untagged_hop(
 385                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 386                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 387         ) {
 388                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 389                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 390                 }, None)) => {
 391                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 392                 },
 393                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 394                         next_node_id, next_blinding_override
 395                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 396                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 397                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 398                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 399                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 400                         // for now.
 401                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 402                                 Ok(pk) => pk,
 403                                 Err(e) => {
 404                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 405                                         return Err(())
 406                                 }
 407                         };
 408                         let outgoing_packet = Packet {
 409                                 version: 0,
 410                                 public_key: new_pubkey,
 411                                 hop_data: new_packet_bytes,
 412                                 hmac: next_hop_hmac,
 413                         };
 414                         let onion_message = OnionMessage {
 415                                 blinding_point: match next_blinding_override {
 416                                         Some(blinding_point) => blinding_point,
 417                                         None => {
 418                                                 match onion_utils::next_hop_pubkey(
 419                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 420                                                 ) {
 421                                                         Ok(bp) => bp,
 422                                                         Err(e) => {
 423                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 424                                                                 return Err(())
 425                                                         }
 426                                                 }
 427                                         }
 428                                 },
 429                                 onion_routing_packet: outgoing_packet,
 430                         };
 431
 432                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 433                 },
 434                 Err(e) => {
 435                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 436                         Err(())
 437                 },
 438                 _ => {
 439                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 440                         Err(())
 441                 },
 442         }
 443 }
 444
 445 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 446 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 447 where
 448         ES::Target: EntropySource,
 449         NS::Target: NodeSigner,
 450         L::Target: Logger,
 451         MR::Target: MessageRouter,
 452         OMH::Target: OffersMessageHandler,
 453         CMH::Target: CustomOnionMessageHandler,
 454 {
 455         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 456         /// their respective handlers.
 457         pub fn new(
 458                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 459                 custom_handler: CMH
 460         ) -> Self {
 461                 let mut secp_ctx = Secp256k1::new();
 462                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 463                 OnionMessenger {
 464                         entropy_source,
 465                         node_signer,
 466                         pending_messages: Mutex::new(HashMap::new()),
 467                         secp_ctx,
 468                         logger,
 469                         message_router,
 470                         offers_handler,
 471                         custom_handler,
 472                 }
 473         }
 474
 475         /// Sends an [`OnionMessage`] with the given `contents` for sending to the destination of
 476         /// `path`.
 477         ///
 478         /// See [`OnionMessenger`] for example usage.
 479         pub fn send_onion_message<T: OnionMessageContents>(
 480                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
 481         ) -> Result<(), SendError> {
 482                 let (first_node_id, onion_msg) = create_onion_message(
 483                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
 484                 )?;
 485
 486                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 487                 if outbound_buffer_full(&first_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
 488                 match pending_per_peer_msgs.entry(first_node_id) {
 489                         hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
 490                         hash_map::Entry::Occupied(mut e) => {
 491                                 e.get_mut().push_back(onion_msg);
 492                                 Ok(())
 493                         }
 494                 }
 495         }
 496
 497         fn handle_onion_message_response<T: OnionMessageContents>(
 498                 &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
 499         ) {
 500                 if let Some(response) = response {
 501                         match reply_path {
 502                                 Some(reply_path) => {
 503                                         self.find_path_and_enqueue_onion_message(
 504                                                 response, Destination::BlindedPath(reply_path), None, log_suffix
 505                                         );
 506                                 },
 507                                 None => {
 508                                         log_trace!(self.logger, "Missing reply path {}", log_suffix);
 509                                 },
 510                         }
 511                 }
 512         }
 513
 514         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 515                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 516                 log_suffix: fmt::Arguments
 517         ) {
 518                 let sender = match self.node_signer.get_node_id(Recipient::Node) {
 519                         Ok(node_id) => node_id,
 520                         Err(_) => {
 521                                 log_warn!(self.logger, "Unable to retrieve node id {}", log_suffix);
 522                                 return;
 523                         }
 524                 };
 525
 526                 let peers = self.pending_messages.lock().unwrap().keys().copied().collect();
 527                 let path = match self.message_router.find_path(sender, peers, destination) {
 528                         Ok(path) => path,
 529                         Err(()) => {
 530                                 log_trace!(self.logger, "Failed to find path {}", log_suffix);
 531                                 return;
 532                         },
 533                 };
 534
 535                 log_trace!(self.logger, "Sending onion message {}", log_suffix);
 536
 537                 if let Err(e) = self.send_onion_message(path, contents, reply_path) {
 538                         log_trace!(self.logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 539                         return;
 540                 }
 541         }
 542
 543         #[cfg(test)]
 544         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 545                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 546                 let mut msgs = HashMap::new();
 547                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 548                 // swap the pending message buffers individually.
 549                 for (peer_node_id, pending_messages) in &mut *pending_msgs {
 550                         msgs.insert(*peer_node_id, core::mem::take(pending_messages));
 551                 }
 552                 msgs
 553         }
 554 }
 555
 556 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<OnionMessage>>) -> bool {
 557         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 558         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 559         let mut total_buffered_bytes = 0;
 560         let mut peer_buffered_bytes = 0;
 561         for (pk, peer_buf) in buffer {
 562                 for om in peer_buf {
 563                         let om_len = om.serialized_length();
 564                         if pk == peer_node_id {
 565                                 peer_buffered_bytes += om_len;
 566                         }
 567                         total_buffered_bytes += om_len;
 568
 569                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 570                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 571                         {
 572                                 return true
 573                         }
 574                 }
 575         }
 576         false
 577 }
 578
 579 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 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 handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
 590                 match peel_onion_message(
 591                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
 592                 ) {
 593                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 594                                 log_trace!(self.logger,
 595                                         "Received an onion message with path_id {:02x?} and {} reply_path",
 596                                                 path_id, if reply_path.is_some() { "a" } else { "no" });
 597
 598                                 match message {
 599                                         ParsedOnionMessageContents::Offers(msg) => {
 600                                                 let response = self.offers_handler.handle_message(msg);
 601                                                 self.handle_onion_message_response(
 602                                                         response, reply_path, format_args!(
 603                                                                 "when responding to Offers onion message with path_id {:02x?}",
 604                                                                 path_id
 605                                                         )
 606                                                 );
 607                                         },
 608                                         ParsedOnionMessageContents::Custom(msg) => {
 609                                                 let response = self.custom_handler.handle_custom_message(msg);
 610                                                 self.handle_onion_message_response(
 611                                                         response, reply_path, format_args!(
 612                                                                 "when responding to Custom onion message with path_id {:02x?}",
 613                                                                 path_id
 614                                                         )
 615                                                 );
 616                                         },
 617                                 }
 618                         },
 619                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 620                                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 621                                 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
 622                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 623                                         return
 624                                 }
 625
 626                                 #[cfg(fuzzing)]
 627                                 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
 628
 629                                 match pending_per_peer_msgs.entry(next_node_id) {
 630                                         hash_map::Entry::Vacant(_) => {
 631                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 632                                                 return
 633                                         },
 634                                         hash_map::Entry::Occupied(mut e) => {
 635                                                 e.get_mut().push_back(onion_message);
 636                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 637                                         }
 638                                 }
 639                         },
 640                         Err(e) => {
 641                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
 642                         }
 643                 }
 644         }
 645
 646         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 647                 if init.features.supports_onion_messages() {
 648                         let mut peers = self.pending_messages.lock().unwrap();
 649                         peers.insert(their_node_id.clone(), VecDeque::new());
 650                 }
 651                 Ok(())
 652         }
 653
 654         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 655                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 656                 pending_msgs.remove(their_node_id);
 657         }
 658
 659         fn provided_node_features(&self) -> NodeFeatures {
 660                 let mut features = NodeFeatures::empty();
 661                 features.set_onion_messages_optional();
 662                 features
 663         }
 664
 665         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
 666                 let mut features = InitFeatures::empty();
 667                 features.set_onion_messages_optional();
 668                 features
 669         }
 670
 671         // Before returning any messages to send for the peer, this method will see if any messages were
 672         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
 673         // node, and then enqueue the message for sending to the first peer in the full path.
 674         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
 675                 // Enqueue any initiating `OffersMessage`s to send.
 676                 for message in self.offers_handler.release_pending_messages() {
 677                         let PendingOnionMessage { contents, destination, reply_path } = message;
 678                         self.find_path_and_enqueue_onion_message(
 679                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
 680                         );
 681                 }
 682
 683                 // Enqueue any initiating `CustomMessage`s to send.
 684                 for message in self.custom_handler.release_pending_custom_messages() {
 685                         let PendingOnionMessage { contents, destination, reply_path } = message;
 686                         self.find_path_and_enqueue_onion_message(
 687                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
 688                         );
 689                 }
 690
 691                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 692                 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
 693                         return msgs.pop_front()
 694                 }
 695                 None
 696         }
 697 }
 698
 699 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
 700 // produces
 701 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 702 /// [`SimpleArcPeerManager`]. See their docs for more details.
 703 ///
 704 /// This is not exported to bindings users as `Arc`s don't make sense in bindings.
 705 ///
 706 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 707 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
 708 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
 709         Arc<KeysManager>,
 710         Arc<KeysManager>,
 711         Arc<L>,
 712         Arc<DefaultMessageRouter>,
 713         Arc<SimpleArcChannelManager<M, T, F, L>>,
 714         IgnoringMessageHandler
 715 >;
 716
 717 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 718 /// [`SimpleRefPeerManager`]. See their docs for more details.
 719 ///
 720 /// This is not exported to bindings users as general type aliases don't make sense in bindings.
 721 ///
 722 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 723 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
 724 pub type SimpleRefOnionMessenger<
 725         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
 726 > = OnionMessenger<
 727         &'a KeysManager,
 728         &'a KeysManager,
 729         &'b L,
 730         &'i DefaultMessageRouter,
 731         &'j SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
 732         IgnoringMessageHandler
 733 >;
 734
 735 /// Construct onion packet payloads and keys for sending an onion message along the given
 736 /// `unblinded_path` to the given `destination`.
 737 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
 738         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
 739         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 740 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 741         let num_hops = unblinded_path.len() + destination.num_hops();
 742         let mut payloads = Vec::with_capacity(num_hops);
 743         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 744
 745         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
 746                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 747                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 748         let num_unblinded_hops = num_hops - num_blinded_hops;
 749
 750         let mut unblinded_path_idx = 0;
 751         let mut blinded_path_idx = 0;
 752         let mut prev_control_tlvs_ss = None;
 753         let mut final_control_tlvs = None;
 754         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
 755                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
 756                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 757                                 if let Some(ss) = prev_control_tlvs_ss.take() {
 758                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
 759                                                 ForwardTlvs {
 760                                                         next_node_id: unblinded_pk_opt.unwrap(),
 761                                                         next_blinding_override: None,
 762                                                 }
 763                                         )), ss));
 764                                 }
 765                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 766                                 unblinded_path_idx += 1;
 767                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
 768                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
 769                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 770                                                 next_node_id: intro_node_id,
 771                                                 next_blinding_override: Some(blinding_pt),
 772                                         })), control_tlvs_ss));
 773                                 }
 774                         }
 775                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
 776                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
 777                                         control_tlvs_ss));
 778                                 blinded_path_idx += 1;
 779                         } else if let Some(encrypted_payload) = enc_payload_opt {
 780                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
 781                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 782                         }
 783
 784                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
 785                         onion_packet_keys.push(onion_utils::OnionKeys {
 786                                 #[cfg(test)]
 787                                 shared_secret: onion_packet_ss,
 788                                 #[cfg(test)]
 789                                 blinding_factor: [0; 32],
 790                                 ephemeral_pubkey,
 791                                 rho,
 792                                 mu,
 793                         });
 794                 }
 795         )?;
 796
 797         if let Some(control_tlvs) = final_control_tlvs {
 798                 payloads.push((Payload::Receive {
 799                         control_tlvs,
 800                         reply_path: reply_path.take(),
 801                         message,
 802                 }, prev_control_tlvs_ss.unwrap()));
 803         } else {
 804                 payloads.push((Payload::Receive {
 805                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
 806                         reply_path: reply_path.take(),
 807                         message,
 808                 }, prev_control_tlvs_ss.unwrap()));
 809         }
 810
 811         Ok((payloads, onion_packet_keys))
 812 }
 813
 814 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
 815 fn construct_onion_message_packet<T: OnionMessageContents>(payloads: Vec<(Payload<T>, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
 816         // Spec rationale:
 817         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
 818         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
 819         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
 820         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
 821         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
 822                 SMALL_PACKET_HOP_DATA_LEN
 823         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
 824                 BIG_PACKET_HOP_DATA_LEN
 825         } else { return Err(()) };
 826
 827         onion_utils::construct_onion_message_packet::<_, _>(
 828                 payloads, onion_keys, prng_seed, hop_data_len)
 829 }