_ 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::OnionMessageContents;
  27 use super::packet::ParsedOnionMessageContents;
  28 use super::offers::OffersMessageHandler;
  29 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  30 use crate::util::logger::Logger;
  31 use crate::util::ser::Writeable;
  32
  33 use core::fmt;
  34 use core::ops::Deref;
  35 use crate::io;
  36 use crate::sync::{Arc, Mutex};
  37 use crate::prelude::*;
  38
  39 /// A sender, receiver and forwarder of [`OnionMessage`]s.
  40 ///
  41 /// # Handling Messages
  42 ///
  43 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
  44 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
  45 /// available handlers are:
  46 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
  47 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
  48 ///
  49 /// # Sending Messages
  50 ///
  51 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
  52 /// a message, the matched handler may return a response message which `OnionMessenger` will send
  53 /// on its behalf.
  54 ///
  55 /// # Example
  56 ///
  57 /// ```
  58 /// # extern crate bitcoin;
  59 /// # use bitcoin::hashes::_export::_core::time::Duration;
  60 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
  61 /// # use lightning::blinded_path::BlindedPath;
  62 /// # use lightning::sign::KeysManager;
  63 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  64 /// # use lightning::onion_message::{OnionMessageContents, Destination, MessageRouter, OnionMessagePath, OnionMessenger};
  65 /// # use lightning::util::logger::{Logger, Record};
  66 /// # use lightning::util::ser::{Writeable, Writer};
  67 /// # use lightning::io;
  68 /// # use std::sync::Arc;
  69 /// # struct FakeLogger;
  70 /// # impl Logger for FakeLogger {
  71 /// #     fn log(&self, record: &Record) { unimplemented!() }
  72 /// # }
  73 /// # struct FakeMessageRouter {}
  74 /// # impl MessageRouter for FakeMessageRouter {
  75 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  76 /// #         unimplemented!()
  77 /// #     }
  78 /// # }
  79 /// # let seed = [42u8; 32];
  80 /// # let time = Duration::from_secs(123456);
  81 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
  82 /// # let logger = Arc::new(FakeLogger {});
  83 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  84 /// # let secp_ctx = Secp256k1::new();
  85 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  86 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
  87 /// # let destination_node_id = hop_node_id1;
  88 /// # let message_router = Arc::new(FakeMessageRouter {});
  89 /// # let custom_message_handler = IgnoringMessageHandler {};
  90 /// # let offers_message_handler = IgnoringMessageHandler {};
  91 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
  92 /// // ChannelManager.
  93 /// let onion_messenger = OnionMessenger::new(
  94 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
  95 ///     &custom_message_handler
  96 /// );
  97 ///
  98 /// # struct YourCustomMessage {}
  99 /// impl Writeable for YourCustomMessage {
 100 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 101 ///             # Ok(())
 102 ///             // Write your custom onion message to `w`
 103 ///     }
 104 /// }
 105 /// impl OnionMessageContents for YourCustomMessage {
 106 ///     fn tlv_type(&self) -> u64 {
 107 ///             # let your_custom_message_type = 42;
 108 ///             your_custom_message_type
 109 ///     }
 110 /// }
 111 /// // Send a custom onion message to a node id.
 112 /// let path = OnionMessagePath {
 113 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 114 ///     destination: Destination::Node(destination_node_id),
 115 /// };
 116 /// let reply_path = None;
 117 /// # let message = YourCustomMessage {};
 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 message = YourCustomMessage {};
 132 /// onion_messenger.send_onion_message(path, message, reply_path);
 133 /// ```
 134 ///
 135 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 136 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 137 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 138 where
 139         ES::Target: EntropySource,
 140         NS::Target: NodeSigner,
 141         L::Target: Logger,
 142         MR::Target: MessageRouter,
 143         OMH::Target: OffersMessageHandler,
 144         CMH:: Target: CustomOnionMessageHandler,
 145 {
 146         entropy_source: ES,
 147         node_signer: NS,
 148         logger: L,
 149         pending_messages: Mutex<HashMap<PublicKey, VecDeque<OnionMessage>>>,
 150         secp_ctx: Secp256k1<secp256k1::All>,
 151         message_router: MR,
 152         offers_handler: OMH,
 153         custom_handler: CMH,
 154 }
 155
 156 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 157 ///
 158 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 159 /// enqueued for sending.
 160 pub struct PendingOnionMessage<T: OnionMessageContents> {
 161         /// The message contents to send in an [`OnionMessage`].
 162         pub contents: T,
 163
 164         /// The destination of the message.
 165         pub destination: Destination,
 166
 167         /// A reply path to include in the [`OnionMessage`] for a response.
 168         pub reply_path: Option<BlindedPath>,
 169 }
 170
 171 /// A trait defining behavior for routing an [`OnionMessage`].
 172 pub trait MessageRouter {
 173         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 174         fn find_path(
 175                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 176         ) -> Result<OnionMessagePath, ()>;
 177 }
 178
 179 /// A [`MessageRouter`] that always fails.
 180 pub struct DefaultMessageRouter;
 181
 182 impl MessageRouter for DefaultMessageRouter {
 183         fn find_path(
 184                 &self, _sender: PublicKey, _peers: Vec<PublicKey>, _destination: Destination
 185         ) -> Result<OnionMessagePath, ()> {
 186                 Err(())
 187         }
 188 }
 189
 190 /// A path for sending an [`OnionMessage`].
 191 #[derive(Clone)]
 192 pub struct OnionMessagePath {
 193         /// Nodes on the path between the sender and the destination.
 194         pub intermediate_nodes: Vec<PublicKey>,
 195
 196         /// The recipient of the message.
 197         pub destination: Destination,
 198 }
 199
 200 /// The destination of an onion message.
 201 #[derive(Clone)]
 202 pub enum Destination {
 203         /// We're sending this onion message to a node.
 204         Node(PublicKey),
 205         /// We're sending this onion message to a blinded path.
 206         BlindedPath(BlindedPath),
 207 }
 208
 209 impl Destination {
 210         pub(super) fn num_hops(&self) -> usize {
 211                 match self {
 212                         Destination::Node(_) => 1,
 213                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 214                 }
 215         }
 216 }
 217
 218 /// Errors that may occur when [sending an onion message].
 219 ///
 220 /// [sending an onion message]: OnionMessenger::send_onion_message
 221 #[derive(Debug, PartialEq, Eq)]
 222 pub enum SendError {
 223         /// Errored computing onion message packet keys.
 224         Secp256k1(secp256k1::Error),
 225         /// Because implementations such as Eclair will drop onion messages where the message packet
 226         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 227         TooBigPacket,
 228         /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two
 229         /// blinded hops.
 230         TooFewBlindedHops,
 231         /// Our next-hop peer was offline or does not support onion message forwarding.
 232         InvalidFirstHop,
 233         /// Onion message contents must have a TLV type >= 64.
 234         InvalidMessage,
 235         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 236         BufferFull,
 237         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 238         ///
 239         /// [`NodeSigner`]: crate::sign::NodeSigner
 240         GetNodeIdFailed,
 241         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 242         /// advance the blinded path to make the second hop the new introduction node. Either
 243         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 244         /// new blinding point, or we were attempting to send to ourselves.
 245         BlindedPathAdvanceFailed,
 246 }
 247
 248 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 249 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 250 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 251 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 252 /// message types.
 253 ///
 254 /// See [`OnionMessenger`] for example usage.
 255 ///
 256 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 257 /// [`CustomMessage`]: Self::CustomMessage
 258 pub trait CustomOnionMessageHandler {
 259         /// The message known to the handler. To support multiple message types, you may want to make this
 260         /// an enum with a variant for each supported message.
 261         type CustomMessage: OnionMessageContents;
 262
 263         /// Called with the custom message that was received, returning a response to send, if any.
 264         ///
 265         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 266         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 267
 268         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 269         /// message type is unknown.
 270         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 271
 272         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 273         ///
 274         /// Typically, this is used for messages initiating a message flow rather than in response to
 275         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 276         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 277 }
 278
 279 /// A processed incoming onion message, containing either a Forward (another onion message)
 280 /// or a Receive payload with decrypted contents.
 281 pub enum PeeledOnion<T: OnionMessageContents> {
 282         /// Forwarded onion, with the next node id and a new onion
 283         Forward(PublicKey, OnionMessage),
 284         /// Received onion message, with decrypted contents, path_id, and reply path
 285         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 286 }
 287
 288 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 289 /// `path`.
 290 ///
 291 /// Returns both the node id of the peer to send the message to and the message itself.
 292 pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
 293         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 294         path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 295 ) -> Result<(PublicKey, OnionMessage), SendError>
 296 where
 297         ES::Target: EntropySource,
 298         NS::Target: NodeSigner,
 299 {
 300         let OnionMessagePath { intermediate_nodes, mut destination } = path;
 301         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 302                 if blinded_hops.len() < 2 {
 303                         return Err(SendError::TooFewBlindedHops);
 304                 }
 305         }
 306
 307         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 308
 309         // If we are sending straight to a blinded path and we are the introduction node, we need to
 310         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 311         if intermediate_nodes.len() == 0 {
 312                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 313                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 314                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 315                         if blinded_path.introduction_node_id == our_node_id {
 316                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 317                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 318                         }
 319                 }
 320         }
 321
 322         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 323         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 324         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 325                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 326         } else {
 327                 match destination {
 328                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 329                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 330                                 (introduction_node_id, blinding_point),
 331                 }
 332         };
 333         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 334                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret)
 335                 .map_err(|e| SendError::Secp256k1(e))?;
 336
 337         let prng_seed = entropy_source.get_secure_random_bytes();
 338         let onion_routing_packet = construct_onion_message_packet(
 339                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 340
 341         Ok((first_node_id, OnionMessage {
 342                 blinding_point,
 343                 onion_routing_packet
 344         }))
 345 }
 346
 347 /// Decode one layer of an incoming onion message
 348 /// Returns either a Forward (another onion message), or Receive (decrypted content)
 349 pub fn peel_onion<NS: Deref, L: Deref, CMH: Deref>(
 350         node_signer: NS, secp_ctx: &Secp256k1<secp256k1::All>, logger: L, custom_handler: CMH,
 351         msg: &OnionMessage,
 352 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 353 where
 354         NS::Target: NodeSigner,
 355         L::Target: Logger,
 356         CMH::Target: CustomOnionMessageHandler,
 357 {
 358         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 359                 Ok(ss) => ss,
 360                 Err(e) =>  {
 361                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 362                         return Err(());
 363                 }
 364         };
 365         let onion_decode_ss = {
 366                 let blinding_factor = {
 367                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 368                         hmac.input(control_tlvs_ss.as_ref());
 369                         Hmac::from_engine(hmac).into_inner()
 370                 };
 371                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 372                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 373                 {
 374                         Ok(ss) => ss.secret_bytes(),
 375                         Err(()) => {
 376                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 377                                 return Err(());
 378                         }
 379                 }
 380         };
 381         match onion_utils::decode_next_untagged_hop(
 382                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 383                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 384         ) {
 385                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 386                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 387                 }, None)) => {
 388                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 389                 },
 390                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 391                         next_node_id, next_blinding_override
 392                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 393                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 394                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 395                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 396                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 397                         // for now.
 398                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 399                                 Ok(pk) => pk,
 400                                 Err(e) => {
 401                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 402                                         return Err(())
 403                                 }
 404                         };
 405                         let outgoing_packet = Packet {
 406                                 version: 0,
 407                                 public_key: new_pubkey,
 408                                 hop_data: new_packet_bytes,
 409                                 hmac: next_hop_hmac,
 410                         };
 411                         let onion_message = OnionMessage {
 412                                 blinding_point: match next_blinding_override {
 413                                         Some(blinding_point) => blinding_point,
 414                                         None => {
 415                                                 match onion_utils::next_hop_pubkey(
 416                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 417                                                 ) {
 418                                                         Ok(bp) => bp,
 419                                                         Err(e) => {
 420                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 421                                                                 return Err(())
 422                                                         }
 423                                                 }
 424                                         }
 425                                 },
 426                                 onion_routing_packet: outgoing_packet,
 427                         };
 428
 429                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 430                 },
 431                 Err(e) => {
 432                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 433                         Err(())
 434                 },
 435                 _ => {
 436                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 437                         Err(())
 438                 },
 439         }
 440 }
 441
 442 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 443 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 444 where
 445         ES::Target: EntropySource,
 446         NS::Target: NodeSigner,
 447         L::Target: Logger,
 448         MR::Target: MessageRouter,
 449         OMH::Target: OffersMessageHandler,
 450         CMH::Target: CustomOnionMessageHandler,
 451 {
 452         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 453         /// their respective handlers.
 454         pub fn new(
 455                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 456                 custom_handler: CMH
 457         ) -> Self {
 458                 let mut secp_ctx = Secp256k1::new();
 459                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 460                 OnionMessenger {
 461                         entropy_source,
 462                         node_signer,
 463                         pending_messages: Mutex::new(HashMap::new()),
 464                         secp_ctx,
 465                         logger,
 466                         message_router,
 467                         offers_handler,
 468                         custom_handler,
 469                 }
 470         }
 471
 472         /// Sends an [`OnionMessage`] with the given `contents` for sending to the destination of
 473         /// `path`.
 474         ///
 475         /// See [`OnionMessenger`] for example usage.
 476         pub fn send_onion_message<T: OnionMessageContents>(
 477                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
 478         ) -> Result<(), SendError> {
 479                 let (first_node_id, onion_msg) = create_onion_message(
 480                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
 481                 )?;
 482
 483                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 484                 if outbound_buffer_full(&first_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
 485                 match pending_per_peer_msgs.entry(first_node_id) {
 486                         hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
 487                         hash_map::Entry::Occupied(mut e) => {
 488                                 e.get_mut().push_back(onion_msg);
 489                                 Ok(())
 490                         }
 491                 }
 492         }
 493
 494         fn handle_onion_message_response<T: OnionMessageContents>(
 495                 &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
 496         ) {
 497                 if let Some(response) = response {
 498                         match reply_path {
 499                                 Some(reply_path) => {
 500                                         self.find_path_and_enqueue_onion_message(
 501                                                 response, Destination::BlindedPath(reply_path), None, log_suffix
 502                                         );
 503                                 },
 504                                 None => {
 505                                         log_trace!(self.logger, "Missing reply path {}", log_suffix);
 506                                 },
 507                         }
 508                 }
 509         }
 510
 511         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 512                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 513                 log_suffix: fmt::Arguments
 514         ) {
 515                 let sender = match self.node_signer.get_node_id(Recipient::Node) {
 516                         Ok(node_id) => node_id,
 517                         Err(_) => {
 518                                 log_warn!(self.logger, "Unable to retrieve node id {}", log_suffix);
 519                                 return;
 520                         }
 521                 };
 522
 523                 let peers = self.pending_messages.lock().unwrap().keys().copied().collect();
 524                 let path = match self.message_router.find_path(sender, peers, destination) {
 525                         Ok(path) => path,
 526                         Err(()) => {
 527                                 log_trace!(self.logger, "Failed to find path {}", log_suffix);
 528                                 return;
 529                         },
 530                 };
 531
 532                 log_trace!(self.logger, "Sending onion message {}", log_suffix);
 533
 534                 if let Err(e) = self.send_onion_message(path, contents, reply_path) {
 535                         log_trace!(self.logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 536                         return;
 537                 }
 538         }
 539
 540         #[cfg(test)]
 541         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 542                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 543                 let mut msgs = HashMap::new();
 544                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 545                 // swap the pending message buffers individually.
 546                 for (peer_node_id, pending_messages) in &mut *pending_msgs {
 547                         msgs.insert(*peer_node_id, core::mem::take(pending_messages));
 548                 }
 549                 msgs
 550         }
 551 }
 552
 553 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<OnionMessage>>) -> bool {
 554         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 555         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 556         let mut total_buffered_bytes = 0;
 557         let mut peer_buffered_bytes = 0;
 558         for (pk, peer_buf) in buffer {
 559                 for om in peer_buf {
 560                         let om_len = om.serialized_length();
 561                         if pk == peer_node_id {
 562                                 peer_buffered_bytes += om_len;
 563                         }
 564                         total_buffered_bytes += om_len;
 565
 566                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 567                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 568                         {
 569                                 return true
 570                         }
 571                 }
 572         }
 573         false
 574 }
 575
 576 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 577 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 578 where
 579         ES::Target: EntropySource,
 580         NS::Target: NodeSigner,
 581         L::Target: Logger,
 582         MR::Target: MessageRouter,
 583         OMH::Target: OffersMessageHandler,
 584         CMH::Target: CustomOnionMessageHandler,
 585 {
 586         /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
 587         /// soon we'll delegate the onion message to a handler that can generate invoices or send
 588         /// payments.
 589         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
 590                 match peel_onion(
 591                         &*self.node_signer, &self.secp_ctx, &*self.logger, &*self.custom_handler, msg
 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<L> = OnionMessenger<
 709         Arc<KeysManager>,
 710         Arc<KeysManager>,
 711         Arc<L>,
 712         Arc<DefaultMessageRouter>,
 713         IgnoringMessageHandler,
 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<'a, 'b, 'c, L> = OnionMessenger<
 725         &'a KeysManager,
 726         &'a KeysManager,
 727         &'b L,
 728         &'c DefaultMessageRouter,
 729         IgnoringMessageHandler,
 730         IgnoringMessageHandler
 731 >;
 732
 733 /// Construct onion packet payloads and keys for sending an onion message along the given
 734 /// `unblinded_path` to the given `destination`.
 735 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
 736         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
 737         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 738 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 739         let num_hops = unblinded_path.len() + destination.num_hops();
 740         let mut payloads = Vec::with_capacity(num_hops);
 741         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 742
 743         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
 744                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 745                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 746         let num_unblinded_hops = num_hops - num_blinded_hops;
 747
 748         let mut unblinded_path_idx = 0;
 749         let mut blinded_path_idx = 0;
 750         let mut prev_control_tlvs_ss = None;
 751         let mut final_control_tlvs = None;
 752         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
 753                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
 754                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 755                                 if let Some(ss) = prev_control_tlvs_ss.take() {
 756                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
 757                                                 ForwardTlvs {
 758                                                         next_node_id: unblinded_pk_opt.unwrap(),
 759                                                         next_blinding_override: None,
 760                                                 }
 761                                         )), ss));
 762                                 }
 763                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 764                                 unblinded_path_idx += 1;
 765                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
 766                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
 767                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 768                                                 next_node_id: intro_node_id,
 769                                                 next_blinding_override: Some(blinding_pt),
 770                                         })), control_tlvs_ss));
 771                                 }
 772                         }
 773                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
 774                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
 775                                         control_tlvs_ss));
 776                                 blinded_path_idx += 1;
 777                         } else if let Some(encrypted_payload) = enc_payload_opt {
 778                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
 779                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 780                         }
 781
 782                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
 783                         onion_packet_keys.push(onion_utils::OnionKeys {
 784                                 #[cfg(test)]
 785                                 shared_secret: onion_packet_ss,
 786                                 #[cfg(test)]
 787                                 blinding_factor: [0; 32],
 788                                 ephemeral_pubkey,
 789                                 rho,
 790                                 mu,
 791                         });
 792                 }
 793         )?;
 794
 795         if let Some(control_tlvs) = final_control_tlvs {
 796                 payloads.push((Payload::Receive {
 797                         control_tlvs,
 798                         reply_path: reply_path.take(),
 799                         message,
 800                 }, prev_control_tlvs_ss.unwrap()));
 801         } else {
 802                 payloads.push((Payload::Receive {
 803                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
 804                         reply_path: reply_path.take(),
 805                         message,
 806                 }, prev_control_tlvs_ss.unwrap()));
 807         }
 808
 809         Ok((payloads, onion_packet_keys))
 810 }
 811
 812 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
 813 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, ()> {
 814         // Spec rationale:
 815         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
 816         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
 817         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
 818         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
 819         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
 820                 SMALL_PACKET_HOP_DATA_LEN
 821         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
 822                 BIG_PACKET_HOP_DATA_LEN
 823         } else { return Err(()) };
 824
 825         onion_utils::construct_onion_message_packet::<_, _>(
 826                 payloads, onion_keys, prng_seed, hop_data_len)
 827 }