_ 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, OnionMessageContents};
  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::ops::Deref;
  33 use crate::io;
  34 use crate::sync::{Arc, Mutex};
  35 use crate::prelude::*;
  36
  37 /// A sender, receiver and forwarder of [`OnionMessage`]s.
  38 ///
  39 /// # Handling Messages
  40 ///
  41 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
  42 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
  43 /// available handlers are:
  44 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
  45 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
  46 ///
  47 /// # Sending Messages
  48 ///
  49 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
  50 /// a message, the matched handler may return a response message which `OnionMessenger` will send
  51 /// on its behalf.
  52 ///
  53 /// # Example
  54 ///
  55 /// ```
  56 /// # extern crate bitcoin;
  57 /// # use bitcoin::hashes::_export::_core::time::Duration;
  58 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
  59 /// # use lightning::blinded_path::BlindedPath;
  60 /// # use lightning::sign::KeysManager;
  61 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  62 /// # use lightning::onion_message::{CustomOnionMessageContents, Destination, MessageRouter, OnionMessageContents, OnionMessagePath, OnionMessenger};
  63 /// # use lightning::util::logger::{Logger, Record};
  64 /// # use lightning::util::ser::{Writeable, Writer};
  65 /// # use lightning::io;
  66 /// # use std::sync::Arc;
  67 /// # struct FakeLogger;
  68 /// # impl Logger for FakeLogger {
  69 /// #     fn log(&self, record: &Record) { unimplemented!() }
  70 /// # }
  71 /// # struct FakeMessageRouter {}
  72 /// # impl MessageRouter for FakeMessageRouter {
  73 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  74 /// #         unimplemented!()
  75 /// #     }
  76 /// # }
  77 /// # let seed = [42u8; 32];
  78 /// # let time = Duration::from_secs(123456);
  79 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
  80 /// # let logger = Arc::new(FakeLogger {});
  81 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  82 /// # let secp_ctx = Secp256k1::new();
  83 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  84 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
  85 /// # let destination_node_id = hop_node_id1;
  86 /// # let message_router = Arc::new(FakeMessageRouter {});
  87 /// # let custom_message_handler = IgnoringMessageHandler {};
  88 /// # let offers_message_handler = IgnoringMessageHandler {};
  89 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
  90 /// // ChannelManager.
  91 /// let onion_messenger = OnionMessenger::new(
  92 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
  93 ///     &custom_message_handler
  94 /// );
  95 ///
  96 /// # struct YourCustomMessage {}
  97 /// impl Writeable for YourCustomMessage {
  98 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  99 ///             # Ok(())
 100 ///             // Write your custom onion message to `w`
 101 ///     }
 102 /// }
 103 /// impl CustomOnionMessageContents for YourCustomMessage {
 104 ///     fn tlv_type(&self) -> u64 {
 105 ///             # let your_custom_message_type = 42;
 106 ///             your_custom_message_type
 107 ///     }
 108 /// }
 109 /// // Send a custom onion message to a node id.
 110 /// let path = OnionMessagePath {
 111 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 112 ///     destination: Destination::Node(destination_node_id),
 113 /// };
 114 /// let reply_path = None;
 115 /// # let your_custom_message = YourCustomMessage {};
 116 /// let message = OnionMessageContents::Custom(your_custom_message);
 117 /// onion_messenger.send_onion_message(path, message, reply_path);
 118 ///
 119 /// // Create a blinded path to yourself, for someone to send an onion message to.
 120 /// # let your_node_id = hop_node_id1;
 121 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 122 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 123 ///
 124 /// // Send a custom onion message to a blinded path.
 125 /// let path = OnionMessagePath {
 126 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 127 ///     destination: Destination::BlindedPath(blinded_path),
 128 /// };
 129 /// let reply_path = None;
 130 /// # let your_custom_message = YourCustomMessage {};
 131 /// let message = OnionMessageContents::Custom(your_custom_message);
 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 /// A trait defining behavior for routing an [`OnionMessage`].
 157 pub trait MessageRouter {
 158         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 159         fn find_path(
 160                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 161         ) -> Result<OnionMessagePath, ()>;
 162 }
 163
 164 /// A [`MessageRouter`] that always fails.
 165 pub struct DefaultMessageRouter;
 166
 167 impl MessageRouter for DefaultMessageRouter {
 168         fn find_path(
 169                 &self, _sender: PublicKey, _peers: Vec<PublicKey>, _destination: Destination
 170         ) -> Result<OnionMessagePath, ()> {
 171                 Err(())
 172         }
 173 }
 174
 175 /// A path for sending an [`OnionMessage`].
 176 #[derive(Clone)]
 177 pub struct OnionMessagePath {
 178         /// Nodes on the path between the sender and the destination.
 179         pub intermediate_nodes: Vec<PublicKey>,
 180
 181         /// The recipient of the message.
 182         pub destination: Destination,
 183 }
 184
 185 /// The destination of an onion message.
 186 #[derive(Clone)]
 187 pub enum Destination {
 188         /// We're sending this onion message to a node.
 189         Node(PublicKey),
 190         /// We're sending this onion message to a blinded path.
 191         BlindedPath(BlindedPath),
 192 }
 193
 194 impl Destination {
 195         pub(super) fn num_hops(&self) -> usize {
 196                 match self {
 197                         Destination::Node(_) => 1,
 198                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 199                 }
 200         }
 201 }
 202
 203 /// Errors that may occur when [sending an onion message].
 204 ///
 205 /// [sending an onion message]: OnionMessenger::send_onion_message
 206 #[derive(Debug, PartialEq, Eq)]
 207 pub enum SendError {
 208         /// Errored computing onion message packet keys.
 209         Secp256k1(secp256k1::Error),
 210         /// Because implementations such as Eclair will drop onion messages where the message packet
 211         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 212         TooBigPacket,
 213         /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two
 214         /// blinded hops.
 215         TooFewBlindedHops,
 216         /// Our next-hop peer was offline or does not support onion message forwarding.
 217         InvalidFirstHop,
 218         /// Onion message contents must have a TLV type >= 64.
 219         InvalidMessage,
 220         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 221         BufferFull,
 222         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 223         ///
 224         /// [`NodeSigner`]: crate::sign::NodeSigner
 225         GetNodeIdFailed,
 226         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 227         /// advance the blinded path to make the second hop the new introduction node. Either
 228         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 229         /// new blinding point, or we were attempting to send to ourselves.
 230         BlindedPathAdvanceFailed,
 231 }
 232
 233 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 234 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 235 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 236 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 237 /// message types.
 238 ///
 239 /// See [`OnionMessenger`] for example usage.
 240 ///
 241 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 242 /// [`CustomMessage`]: Self::CustomMessage
 243 pub trait CustomOnionMessageHandler {
 244         /// The message known to the handler. To support multiple message types, you may want to make this
 245         /// an enum with a variant for each supported message.
 246         type CustomMessage: CustomOnionMessageContents;
 247
 248         /// Called with the custom message that was received, returning a response to send, if any.
 249         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 250
 251         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 252         /// message type is unknown.
 253         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 254 }
 255
 256 /// A processed incoming onion message, containing either a Forward (another onion message)
 257 /// or a Receive payload with decrypted contents.
 258 pub enum PeeledOnion<CM: CustomOnionMessageContents> {
 259         /// Forwarded onion, with the next node id and a new onion
 260         Forward(PublicKey, OnionMessage),
 261         /// Received onion message, with decrypted contents, path_id, and reply path
 262         Receive(OnionMessageContents<CM>, Option<[u8; 32]>, Option<BlindedPath>)
 263 }
 264
 265 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 266 /// `path`.
 267 ///
 268 /// Returns both the node id of the peer to send the message to and the message itself.
 269 pub fn create_onion_message<ES: Deref, NS: Deref, T: CustomOnionMessageContents>(
 270         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 271         path: OnionMessagePath, contents: OnionMessageContents<T>, reply_path: Option<BlindedPath>,
 272 ) -> Result<(PublicKey, OnionMessage), SendError>
 273 where
 274         ES::Target: EntropySource,
 275         NS::Target: NodeSigner,
 276 {
 277         let OnionMessagePath { intermediate_nodes, mut destination } = path;
 278         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 279                 if blinded_hops.len() < 2 {
 280                         return Err(SendError::TooFewBlindedHops);
 281                 }
 282         }
 283
 284         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 285
 286         // If we are sending straight to a blinded path and we are the introduction node, we need to
 287         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 288         if intermediate_nodes.len() == 0 {
 289                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 290                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 291                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 292                         if blinded_path.introduction_node_id == our_node_id {
 293                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 294                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 295                         }
 296                 }
 297         }
 298
 299         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 300         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 301         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 302                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 303         } else {
 304                 match destination {
 305                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 306                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 307                                 (introduction_node_id, blinding_point),
 308                 }
 309         };
 310         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 311                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret)
 312                 .map_err(|e| SendError::Secp256k1(e))?;
 313
 314         let prng_seed = entropy_source.get_secure_random_bytes();
 315         let onion_routing_packet = construct_onion_message_packet(
 316                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 317
 318         Ok((first_node_id, OnionMessage {
 319                 blinding_point,
 320                 onion_routing_packet
 321         }))
 322 }
 323
 324 /// Decode one layer of an incoming onion message
 325 /// Returns either a Forward (another onion message), or Receive (decrypted content)
 326 pub fn peel_onion<NS: Deref, L: Deref, CMH: Deref>(
 327         node_signer: NS, secp_ctx: &Secp256k1<secp256k1::All>, logger: L, custom_handler: CMH,
 328         msg: &OnionMessage,
 329 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 330 where
 331         NS::Target: NodeSigner,
 332         L::Target: Logger,
 333         CMH::Target: CustomOnionMessageHandler,
 334 {
 335         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 336                 Ok(ss) => ss,
 337                 Err(e) =>  {
 338                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 339                         return Err(());
 340                 }
 341         };
 342         let onion_decode_ss = {
 343                 let blinding_factor = {
 344                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 345                         hmac.input(control_tlvs_ss.as_ref());
 346                         Hmac::from_engine(hmac).into_inner()
 347                 };
 348                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 349                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 350                 {
 351                         Ok(ss) => ss.secret_bytes(),
 352                         Err(()) => {
 353                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 354                                 return Err(());
 355                         }
 356                 }
 357         };
 358         match onion_utils::decode_next_untagged_hop(
 359                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 360                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 361         ) {
 362                 Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
 363                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 364                 }, None)) => {
 365                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 366                 },
 367                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 368                         next_node_id, next_blinding_override
 369                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 370                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 371                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 372                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 373                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 374                         // for now.
 375                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 376                                 Ok(pk) => pk,
 377                                 Err(e) => {
 378                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 379                                         return Err(())
 380                                 }
 381                         };
 382                         let outgoing_packet = Packet {
 383                                 version: 0,
 384                                 public_key: new_pubkey,
 385                                 hop_data: new_packet_bytes,
 386                                 hmac: next_hop_hmac,
 387                         };
 388                         let onion_message = OnionMessage {
 389                                 blinding_point: match next_blinding_override {
 390                                         Some(blinding_point) => blinding_point,
 391                                         None => {
 392                                                 match onion_utils::next_hop_pubkey(
 393                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 394                                                 ) {
 395                                                         Ok(bp) => bp,
 396                                                         Err(e) => {
 397                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 398                                                                 return Err(())
 399                                                         }
 400                                                 }
 401                                         }
 402                                 },
 403                                 onion_routing_packet: outgoing_packet,
 404                         };
 405
 406                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 407                 },
 408                 Err(e) => {
 409                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 410                         Err(())
 411                 },
 412                 _ => {
 413                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 414                         Err(())
 415                 },
 416         }
 417 }
 418
 419 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 420 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 421 where
 422         ES::Target: EntropySource,
 423         NS::Target: NodeSigner,
 424         L::Target: Logger,
 425         MR::Target: MessageRouter,
 426         OMH::Target: OffersMessageHandler,
 427         CMH::Target: CustomOnionMessageHandler,
 428 {
 429         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 430         /// their respective handlers.
 431         pub fn new(
 432                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 433                 custom_handler: CMH
 434         ) -> Self {
 435                 let mut secp_ctx = Secp256k1::new();
 436                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 437                 OnionMessenger {
 438                         entropy_source,
 439                         node_signer,
 440                         pending_messages: Mutex::new(HashMap::new()),
 441                         secp_ctx,
 442                         logger,
 443                         message_router,
 444                         offers_handler,
 445                         custom_handler,
 446                 }
 447         }
 448
 449         /// Sends an [`OnionMessage`] with the given `contents` for sending to the destination of
 450         /// `path`.
 451         ///
 452         /// See [`OnionMessenger`] for example usage.
 453         pub fn send_onion_message<T: CustomOnionMessageContents>(
 454                 &self, path: OnionMessagePath, contents: OnionMessageContents<T>,
 455                 reply_path: Option<BlindedPath>
 456         ) -> Result<(), SendError> {
 457                 let (first_node_id, onion_msg) = create_onion_message(
 458                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
 459                 )?;
 460
 461                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 462                 if outbound_buffer_full(&first_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
 463                 match pending_per_peer_msgs.entry(first_node_id) {
 464                         hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
 465                         hash_map::Entry::Occupied(mut e) => {
 466                                 e.get_mut().push_back(onion_msg);
 467                                 Ok(())
 468                         }
 469                 }
 470         }
 471
 472         fn respond_with_onion_message<T: CustomOnionMessageContents>(
 473                 &self, response: OnionMessageContents<T>, path_id: Option<[u8; 32]>,
 474                 reply_path: Option<BlindedPath>
 475         ) {
 476                 let sender = match self.node_signer.get_node_id(Recipient::Node) {
 477                         Ok(node_id) => node_id,
 478                         Err(_) => {
 479                                 log_warn!(
 480                                         self.logger, "Unable to retrieve node id when responding to onion message with \
 481                                         path_id {:02x?}", path_id
 482                                 );
 483                                 return;
 484                         }
 485                 };
 486
 487                 let peers = self.pending_messages.lock().unwrap().keys().copied().collect();
 488
 489                 let destination = match reply_path {
 490                         Some(reply_path) => Destination::BlindedPath(reply_path),
 491                         None => {
 492                                 log_trace!(
 493                                         self.logger, "Missing reply path when responding to onion message with path_id \
 494                                         {:02x?}", path_id
 495                                 );
 496                                 return;
 497                         },
 498                 };
 499
 500                 let path = match self.message_router.find_path(sender, peers, destination) {
 501                         Ok(path) => path,
 502                         Err(()) => {
 503                                 log_trace!(
 504                                         self.logger, "Failed to find path when responding to onion message with \
 505                                         path_id {:02x?}", path_id
 506                                 );
 507                                 return;
 508                         },
 509                 };
 510
 511                 log_trace!(self.logger, "Responding to onion message with path_id {:02x?}", path_id);
 512
 513                 if let Err(e) = self.send_onion_message(path, response, None) {
 514                         log_trace!(
 515                                 self.logger, "Failed responding to onion message with path_id {:02x?}: {:?}",
 516                                 path_id, e
 517                         );
 518                         return;
 519                 }
 520         }
 521
 522         #[cfg(test)]
 523         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 524                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 525                 let mut msgs = HashMap::new();
 526                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 527                 // swap the pending message buffers individually.
 528                 for (peer_node_id, pending_messages) in &mut *pending_msgs {
 529                         msgs.insert(*peer_node_id, core::mem::take(pending_messages));
 530                 }
 531                 msgs
 532         }
 533 }
 534
 535 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<OnionMessage>>) -> bool {
 536         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 537         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 538         let mut total_buffered_bytes = 0;
 539         let mut peer_buffered_bytes = 0;
 540         for (pk, peer_buf) in buffer {
 541                 for om in peer_buf {
 542                         let om_len = om.serialized_length();
 543                         if pk == peer_node_id {
 544                                 peer_buffered_bytes += om_len;
 545                         }
 546                         total_buffered_bytes += om_len;
 547
 548                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 549                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 550                         {
 551                                 return true
 552                         }
 553                 }
 554         }
 555         false
 556 }
 557
 558 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 559 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 560 where
 561         ES::Target: EntropySource,
 562         NS::Target: NodeSigner,
 563         L::Target: Logger,
 564         MR::Target: MessageRouter,
 565         OMH::Target: OffersMessageHandler,
 566         CMH::Target: CustomOnionMessageHandler,
 567 {
 568         /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
 569         /// soon we'll delegate the onion message to a handler that can generate invoices or send
 570         /// payments.
 571         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
 572                 match peel_onion(
 573                         &*self.node_signer, &self.secp_ctx, &*self.logger, &*self.custom_handler, msg
 574                 ) {
 575                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 576                                 log_trace!(self.logger,
 577                                         "Received an onion message with path_id {:02x?} and {} reply_path",
 578                                                 path_id, if reply_path.is_some() { "a" } else { "no" });
 579                                 let response = match message {
 580                                         OnionMessageContents::Offers(msg) => {
 581                                                 self.offers_handler.handle_message(msg)
 582                                                         .map(|msg| OnionMessageContents::Offers(msg))
 583                                         },
 584                                         OnionMessageContents::Custom(msg) => {
 585                                                 self.custom_handler.handle_custom_message(msg)
 586                                                         .map(|msg| OnionMessageContents::Custom(msg))
 587                                         },
 588                                 };
 589                                 if let Some(response) = response {
 590                                         self.respond_with_onion_message(response, path_id, reply_path);
 591                                 }
 592                         },
 593                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 594                                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 595                                 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
 596                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 597                                         return
 598                                 }
 599
 600                                 #[cfg(fuzzing)]
 601                                 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
 602
 603                                 match pending_per_peer_msgs.entry(next_node_id) {
 604                                         hash_map::Entry::Vacant(_) => {
 605                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 606                                                 return
 607                                         },
 608                                         hash_map::Entry::Occupied(mut e) => {
 609                                                 e.get_mut().push_back(onion_message);
 610                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 611                                         }
 612                                 }
 613                         },
 614                         Err(e) => {
 615                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
 616                         }
 617                 }
 618         }
 619
 620         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 621                 if init.features.supports_onion_messages() {
 622                         let mut peers = self.pending_messages.lock().unwrap();
 623                         peers.insert(their_node_id.clone(), VecDeque::new());
 624                 }
 625                 Ok(())
 626         }
 627
 628         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 629                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 630                 pending_msgs.remove(their_node_id);
 631         }
 632
 633         fn provided_node_features(&self) -> NodeFeatures {
 634                 let mut features = NodeFeatures::empty();
 635                 features.set_onion_messages_optional();
 636                 features
 637         }
 638
 639         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
 640                 let mut features = InitFeatures::empty();
 641                 features.set_onion_messages_optional();
 642                 features
 643         }
 644
 645         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
 646                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 647                 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
 648                         return msgs.pop_front()
 649                 }
 650                 None
 651         }
 652 }
 653
 654 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
 655 // produces
 656 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 657 /// [`SimpleArcPeerManager`]. See their docs for more details.
 658 ///
 659 /// This is not exported to bindings users as `Arc`s don't make sense in bindings.
 660 ///
 661 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 662 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
 663 pub type SimpleArcOnionMessenger<L> = OnionMessenger<
 664         Arc<KeysManager>,
 665         Arc<KeysManager>,
 666         Arc<L>,
 667         Arc<DefaultMessageRouter>,
 668         IgnoringMessageHandler,
 669         IgnoringMessageHandler
 670 >;
 671
 672 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 673 /// [`SimpleRefPeerManager`]. See their docs for more details.
 674 ///
 675 /// This is not exported to bindings users as general type aliases don't make sense in bindings.
 676 ///
 677 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 678 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
 679 pub type SimpleRefOnionMessenger<'a, 'b, 'c, L> = OnionMessenger<
 680         &'a KeysManager,
 681         &'a KeysManager,
 682         &'b L,
 683         &'c DefaultMessageRouter,
 684         IgnoringMessageHandler,
 685         IgnoringMessageHandler
 686 >;
 687
 688 /// Construct onion packet payloads and keys for sending an onion message along the given
 689 /// `unblinded_path` to the given `destination`.
 690 fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
 691         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
 692         message: OnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 693 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 694         let num_hops = unblinded_path.len() + destination.num_hops();
 695         let mut payloads = Vec::with_capacity(num_hops);
 696         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 697
 698         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
 699                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 700                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 701         let num_unblinded_hops = num_hops - num_blinded_hops;
 702
 703         let mut unblinded_path_idx = 0;
 704         let mut blinded_path_idx = 0;
 705         let mut prev_control_tlvs_ss = None;
 706         let mut final_control_tlvs = None;
 707         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
 708                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
 709                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 710                                 if let Some(ss) = prev_control_tlvs_ss.take() {
 711                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
 712                                                 ForwardTlvs {
 713                                                         next_node_id: unblinded_pk_opt.unwrap(),
 714                                                         next_blinding_override: None,
 715                                                 }
 716                                         )), ss));
 717                                 }
 718                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 719                                 unblinded_path_idx += 1;
 720                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
 721                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
 722                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 723                                                 next_node_id: intro_node_id,
 724                                                 next_blinding_override: Some(blinding_pt),
 725                                         })), control_tlvs_ss));
 726                                 }
 727                         }
 728                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
 729                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
 730                                         control_tlvs_ss));
 731                                 blinded_path_idx += 1;
 732                         } else if let Some(encrypted_payload) = enc_payload_opt {
 733                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
 734                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 735                         }
 736
 737                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
 738                         onion_packet_keys.push(onion_utils::OnionKeys {
 739                                 #[cfg(test)]
 740                                 shared_secret: onion_packet_ss,
 741                                 #[cfg(test)]
 742                                 blinding_factor: [0; 32],
 743                                 ephemeral_pubkey,
 744                                 rho,
 745                                 mu,
 746                         });
 747                 }
 748         )?;
 749
 750         if let Some(control_tlvs) = final_control_tlvs {
 751                 payloads.push((Payload::Receive {
 752                         control_tlvs,
 753                         reply_path: reply_path.take(),
 754                         message,
 755                 }, prev_control_tlvs_ss.unwrap()));
 756         } else {
 757                 payloads.push((Payload::Receive {
 758                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
 759                         reply_path: reply_path.take(),
 760                         message,
 761                 }, prev_control_tlvs_ss.unwrap()));
 762         }
 763
 764         Ok((payloads, onion_packet_keys))
 765 }
 766
 767 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
 768 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, ()> {
 769         // Spec rationale:
 770         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
 771         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
 772         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
 773         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
 774         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
 775                 SMALL_PACKET_HOP_DATA_LEN
 776         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
 777                 BIG_PACKET_HOP_DATA_LEN
 778         } else { return Err(()) };
 779
 780         onion_utils::construct_onion_message_packet::<_, _>(
 781                 payloads, onion_keys, prng_seed, hop_data_len)
 782 }