_ 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::events::OnionMessageProvider;
  23 use crate::ln::features::{InitFeatures, NodeFeatures};
  24 use crate::ln::msgs::{self, OnionMessageHandler};
  25 use crate::ln::onion_utils;
  26 use crate::ln::peer_handler::IgnoringMessageHandler;
  27 pub use super::packet::{CustomOnionMessageContents, OnionMessageContents};
  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::ops::Deref;
  34 use crate::io;
  35 use crate::sync::{Arc, Mutex};
  36 use crate::prelude::*;
  37
  38 /// A sender, receiver and forwarder of [`OnionMessage`]s.
  39 ///
  40 /// # Handling Messages
  41 ///
  42 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
  43 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
  44 /// available handlers are:
  45 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
  46 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
  47 ///
  48 /// # Sending Messages
  49 ///
  50 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
  51 /// a message, the matched handler may return a response message which `OnionMessenger` will send
  52 /// on its behalf.
  53 ///
  54 /// # Example
  55 ///
  56 /// ```
  57 /// # extern crate bitcoin;
  58 /// # use bitcoin::hashes::_export::_core::time::Duration;
  59 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
  60 /// # use lightning::blinded_path::BlindedPath;
  61 /// # use lightning::sign::KeysManager;
  62 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  63 /// # use lightning::onion_message::{CustomOnionMessageContents, Destination, MessageRouter, OnionMessageContents, OnionMessagePath, OnionMessenger};
  64 /// # use lightning::util::logger::{Logger, Record};
  65 /// # use lightning::util::ser::{Writeable, Writer};
  66 /// # use lightning::io;
  67 /// # use std::sync::Arc;
  68 /// # struct FakeLogger;
  69 /// # impl Logger for FakeLogger {
  70 /// #     fn log(&self, record: &Record) { unimplemented!() }
  71 /// # }
  72 /// # struct FakeMessageRouter {}
  73 /// # impl MessageRouter for FakeMessageRouter {
  74 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  75 /// #         unimplemented!()
  76 /// #     }
  77 /// # }
  78 /// # let seed = [42u8; 32];
  79 /// # let time = Duration::from_secs(123456);
  80 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
  81 /// # let logger = Arc::new(FakeLogger {});
  82 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  83 /// # let secp_ctx = Secp256k1::new();
  84 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  85 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
  86 /// # let destination_node_id = hop_node_id1;
  87 /// # let message_router = Arc::new(FakeMessageRouter {});
  88 /// # let custom_message_handler = IgnoringMessageHandler {};
  89 /// # let offers_message_handler = IgnoringMessageHandler {};
  90 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
  91 /// // ChannelManager.
  92 /// let onion_messenger = OnionMessenger::new(
  93 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
  94 ///     &custom_message_handler
  95 /// );
  96 ///
  97 /// # struct YourCustomMessage {}
  98 /// impl Writeable for YourCustomMessage {
  99 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 100 ///             # Ok(())
 101 ///             // Write your custom onion message to `w`
 102 ///     }
 103 /// }
 104 /// impl CustomOnionMessageContents for YourCustomMessage {
 105 ///     fn tlv_type(&self) -> u64 {
 106 ///             # let your_custom_message_type = 42;
 107 ///             your_custom_message_type
 108 ///     }
 109 /// }
 110 /// // Send a custom onion message to a node id.
 111 /// let path = OnionMessagePath {
 112 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 113 ///     destination: Destination::Node(destination_node_id),
 114 /// };
 115 /// let reply_path = None;
 116 /// # let your_custom_message = YourCustomMessage {};
 117 /// let message = OnionMessageContents::Custom(your_custom_message);
 118 /// onion_messenger.send_onion_message(path, message, reply_path);
 119 ///
 120 /// // Create a blinded path to yourself, for someone to send an onion message to.
 121 /// # let your_node_id = hop_node_id1;
 122 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 123 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 124 ///
 125 /// // Send a custom onion message to a blinded path.
 126 /// let path = OnionMessagePath {
 127 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 128 ///     destination: Destination::BlindedPath(blinded_path),
 129 /// };
 130 /// let reply_path = None;
 131 /// # let your_custom_message = YourCustomMessage {};
 132 /// let message = OnionMessageContents::Custom(your_custom_message);
 133 /// onion_messenger.send_onion_message(path, message, reply_path);
 134 /// ```
 135 ///
 136 /// [`OnionMessage`]: crate::ln::msgs::OnionMessage
 137 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 138 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 139 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 140 where
 141         ES::Target: EntropySource,
 142         NS::Target: NodeSigner,
 143         L::Target: Logger,
 144         MR::Target: MessageRouter,
 145         OMH::Target: OffersMessageHandler,
 146         CMH:: Target: CustomOnionMessageHandler,
 147 {
 148         entropy_source: ES,
 149         node_signer: NS,
 150         logger: L,
 151         pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
 152         secp_ctx: Secp256k1<secp256k1::All>,
 153         message_router: MR,
 154         offers_handler: OMH,
 155         custom_handler: CMH,
 156 }
 157
 158 /// A trait defining behavior for routing an [`OnionMessage`].
 159 ///
 160 /// [`OnionMessage`]: msgs::OnionMessage
 161 pub trait MessageRouter {
 162         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 163         ///
 164         /// [`OnionMessage`]: msgs::OnionMessage
 165         fn find_path(
 166                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 167         ) -> Result<OnionMessagePath, ()>;
 168 }
 169
 170 /// A [`MessageRouter`] that always fails.
 171 pub struct DefaultMessageRouter;
 172
 173 impl MessageRouter for DefaultMessageRouter {
 174         fn find_path(
 175                 &self, _sender: PublicKey, _peers: Vec<PublicKey>, _destination: Destination
 176         ) -> Result<OnionMessagePath, ()> {
 177                 Err(())
 178         }
 179 }
 180
 181 /// A path for sending an [`msgs::OnionMessage`].
 182 #[derive(Clone)]
 183 pub struct OnionMessagePath {
 184         /// Nodes on the path between the sender and the destination.
 185         pub intermediate_nodes: Vec<PublicKey>,
 186
 187         /// The recipient of the message.
 188         pub destination: Destination,
 189 }
 190
 191 /// The destination of an onion message.
 192 #[derive(Clone)]
 193 pub enum Destination {
 194         /// We're sending this onion message to a node.
 195         Node(PublicKey),
 196         /// We're sending this onion message to a blinded path.
 197         BlindedPath(BlindedPath),
 198 }
 199
 200 impl Destination {
 201         pub(super) fn num_hops(&self) -> usize {
 202                 match self {
 203                         Destination::Node(_) => 1,
 204                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 205                 }
 206         }
 207 }
 208
 209 /// Errors that may occur when [sending an onion message].
 210 ///
 211 /// [sending an onion message]: OnionMessenger::send_onion_message
 212 #[derive(Debug, PartialEq, Eq)]
 213 pub enum SendError {
 214         /// Errored computing onion message packet keys.
 215         Secp256k1(secp256k1::Error),
 216         /// Because implementations such as Eclair will drop onion messages where the message packet
 217         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 218         TooBigPacket,
 219         /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two
 220         /// blinded hops.
 221         TooFewBlindedHops,
 222         /// Our next-hop peer was offline or does not support onion message forwarding.
 223         InvalidFirstHop,
 224         /// Onion message contents must have a TLV type >= 64.
 225         InvalidMessage,
 226         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 227         BufferFull,
 228         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 229         ///
 230         /// [`NodeSigner`]: crate::sign::NodeSigner
 231         GetNodeIdFailed,
 232         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 233         /// advance the blinded path to make the second hop the new introduction node. Either
 234         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 235         /// new blinding point, or we were attempting to send to ourselves.
 236         BlindedPathAdvanceFailed,
 237 }
 238
 239 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 240 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 241 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 242 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 243 /// message types.
 244 ///
 245 /// See [`OnionMessenger`] for example usage.
 246 ///
 247 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 248 /// [`CustomMessage`]: Self::CustomMessage
 249 pub trait CustomOnionMessageHandler {
 250         /// The message known to the handler. To support multiple message types, you may want to make this
 251         /// an enum with a variant for each supported message.
 252         type CustomMessage: CustomOnionMessageContents;
 253
 254         /// Called with the custom message that was received, returning a response to send, if any.
 255         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 256
 257         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 258         /// message type is unknown.
 259         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 260 }
 261
 262 /// A processed incoming onion message, containing either a Forward (another onion message)
 263 /// or a Receive payload with decrypted contents.
 264 pub enum PeeledOnion<CM: CustomOnionMessageContents> {
 265         /// Forwarded onion, with the next node id and a new onion
 266         Forward(PublicKey, msgs::OnionMessage),
 267         /// Received onion message, with decrypted contents, path_id, and reply path
 268         Receive(OnionMessageContents<CM>, Option<[u8; 32]>, Option<BlindedPath>)
 269 }
 270
 271 /// Create an onion message with contents `message` to the destination of `path`.
 272 /// Returns (introduction_node_id, onion_msg)
 273 pub fn create_onion_message<ES: Deref, NS: Deref, T: CustomOnionMessageContents>(
 274         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 275         path: OnionMessagePath, message: OnionMessageContents<T>, reply_path: Option<BlindedPath>,
 276 ) -> Result<(PublicKey, msgs::OnionMessage), SendError>
 277 where
 278         ES::Target: EntropySource,
 279         NS::Target: NodeSigner,
 280 {
 281         let OnionMessagePath { intermediate_nodes, mut destination } = path;
 282         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 283                 if blinded_hops.len() < 2 {
 284                         return Err(SendError::TooFewBlindedHops);
 285                 }
 286         }
 287
 288         if message.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 289
 290         // If we are sending straight to a blinded path and we are the introduction node, we need to
 291         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 292         if intermediate_nodes.len() == 0 {
 293                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 294                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 295                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 296                         if blinded_path.introduction_node_id == our_node_id {
 297                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 298                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 299                         }
 300                 }
 301         }
 302
 303         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 304         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 305         let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
 306                 (intermediate_nodes[0], PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 307         } else {
 308                 match destination {
 309                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 310                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 311                                 (introduction_node_id, blinding_point),
 312                 }
 313         };
 314         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 315                 &secp_ctx, &intermediate_nodes, destination, message, reply_path, &blinding_secret)
 316                 .map_err(|e| SendError::Secp256k1(e))?;
 317
 318         let prng_seed = entropy_source.get_secure_random_bytes();
 319         let onion_routing_packet = construct_onion_message_packet(
 320                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 321
 322         Ok((introduction_node_id, msgs::OnionMessage {
 323                 blinding_point,
 324                 onion_routing_packet
 325         }))
 326 }
 327
 328 /// Decode one layer of an incoming onion message
 329 /// Returns either a Forward (another onion message), or Receive (decrypted content)
 330 pub fn peel_onion<NS: Deref, L: Deref, CMH: Deref>(
 331         node_signer: NS, secp_ctx: &Secp256k1<secp256k1::All>, logger: L, custom_handler: CMH,
 332         msg: &msgs::OnionMessage,
 333 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 334 where
 335         NS::Target: NodeSigner,
 336         L::Target: Logger,
 337         CMH::Target: CustomOnionMessageHandler,
 338 {
 339         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 340                 Ok(ss) => ss,
 341                 Err(e) =>  {
 342                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 343                         return Err(());
 344                 }
 345         };
 346         let onion_decode_ss = {
 347                 let blinding_factor = {
 348                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 349                         hmac.input(control_tlvs_ss.as_ref());
 350                         Hmac::from_engine(hmac).into_inner()
 351                 };
 352                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 353                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 354                 {
 355                         Ok(ss) => ss.secret_bytes(),
 356                         Err(()) => {
 357                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 358                                 return Err(());
 359                         }
 360                 }
 361         };
 362         match onion_utils::decode_next_untagged_hop(
 363                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 364                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 365         ) {
 366                 Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
 367                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 368                 }, None)) => {
 369                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 370                 },
 371                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 372                         next_node_id, next_blinding_override
 373                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 374                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 375                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 376                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 377                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 378                         // for now.
 379                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 380                                 Ok(pk) => pk,
 381                                 Err(e) => {
 382                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 383                                         return Err(())
 384                                 }
 385                         };
 386                         let outgoing_packet = Packet {
 387                                 version: 0,
 388                                 public_key: new_pubkey,
 389                                 hop_data: new_packet_bytes,
 390                                 hmac: next_hop_hmac,
 391                         };
 392                         let onion_message = msgs::OnionMessage {
 393                                 blinding_point: match next_blinding_override {
 394                                         Some(blinding_point) => blinding_point,
 395                                         None => {
 396                                                 match onion_utils::next_hop_pubkey(
 397                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 398                                                 ) {
 399                                                         Ok(bp) => bp,
 400                                                         Err(e) => {
 401                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 402                                                                 return Err(())
 403                                                         }
 404                                                 }
 405                                         }
 406                                 },
 407                                 onion_routing_packet: outgoing_packet,
 408                         };
 409
 410                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 411                 },
 412                 Err(e) => {
 413                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 414                         Err(())
 415                 },
 416                 _ => {
 417                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 418                         Err(())
 419                 },
 420         }
 421 }
 422
 423 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 424 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 425 where
 426         ES::Target: EntropySource,
 427         NS::Target: NodeSigner,
 428         L::Target: Logger,
 429         MR::Target: MessageRouter,
 430         OMH::Target: OffersMessageHandler,
 431         CMH::Target: CustomOnionMessageHandler,
 432 {
 433         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 434         /// their respective handlers.
 435         pub fn new(
 436                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 437                 custom_handler: CMH
 438         ) -> Self {
 439                 let mut secp_ctx = Secp256k1::new();
 440                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 441                 OnionMessenger {
 442                         entropy_source,
 443                         node_signer,
 444                         pending_messages: Mutex::new(HashMap::new()),
 445                         secp_ctx,
 446                         logger,
 447                         message_router,
 448                         offers_handler,
 449                         custom_handler,
 450                 }
 451         }
 452
 453         /// Send an onion message with contents `message` to the destination of `path`.
 454         ///
 455         /// See [`OnionMessenger`] for example usage.
 456         pub fn send_onion_message<T: CustomOnionMessageContents>(
 457                 &self, path: OnionMessagePath, message: OnionMessageContents<T>,
 458                 reply_path: Option<BlindedPath>
 459         ) -> Result<(), SendError> {
 460                 let (introduction_node_id, onion_msg) = create_onion_message(
 461                         &self.entropy_source, &self.node_signer, &self.secp_ctx,
 462                         path, message, reply_path
 463                 )?;
 464
 465                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 466                 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
 467                 match pending_per_peer_msgs.entry(introduction_node_id) {
 468                         hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
 469                         hash_map::Entry::Occupied(mut e) => {
 470                                 e.get_mut().push_back(onion_msg);
 471                                 Ok(())
 472                         }
 473                 }
 474         }
 475
 476         fn respond_with_onion_message<T: CustomOnionMessageContents>(
 477                 &self, response: OnionMessageContents<T>, path_id: Option<[u8; 32]>,
 478                 reply_path: Option<BlindedPath>
 479         ) {
 480                 let sender = match self.node_signer.get_node_id(Recipient::Node) {
 481                         Ok(node_id) => node_id,
 482                         Err(_) => {
 483                                 log_warn!(
 484                                         self.logger, "Unable to retrieve node id when responding to onion message with \
 485                                         path_id {:02x?}", path_id
 486                                 );
 487                                 return;
 488                         }
 489                 };
 490
 491                 let peers = self.pending_messages.lock().unwrap().keys().copied().collect();
 492
 493                 let destination = match reply_path {
 494                         Some(reply_path) => Destination::BlindedPath(reply_path),
 495                         None => {
 496                                 log_trace!(
 497                                         self.logger, "Missing reply path when responding to onion message with path_id \
 498                                         {:02x?}", path_id
 499                                 );
 500                                 return;
 501                         },
 502                 };
 503
 504                 let path = match self.message_router.find_path(sender, peers, destination) {
 505                         Ok(path) => path,
 506                         Err(()) => {
 507                                 log_trace!(
 508                                         self.logger, "Failed to find path when responding to onion message with \
 509                                         path_id {:02x?}", path_id
 510                                 );
 511                                 return;
 512                         },
 513                 };
 514
 515                 log_trace!(self.logger, "Responding to onion message with path_id {:02x?}", path_id);
 516
 517                 if let Err(e) = self.send_onion_message(path, response, None) {
 518                         log_trace!(
 519                                 self.logger, "Failed responding to onion message with path_id {:02x?}: {:?}",
 520                                 path_id, e
 521                         );
 522                         return;
 523                 }
 524         }
 525
 526         #[cfg(test)]
 527         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
 528                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 529                 let mut msgs = HashMap::new();
 530                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 531                 // swap the pending message buffers individually.
 532                 for (peer_node_id, pending_messages) in &mut *pending_msgs {
 533                         msgs.insert(*peer_node_id, core::mem::take(pending_messages));
 534                 }
 535                 msgs
 536         }
 537 }
 538
 539 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
 540         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 541         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 542         let mut total_buffered_bytes = 0;
 543         let mut peer_buffered_bytes = 0;
 544         for (pk, peer_buf) in buffer {
 545                 for om in peer_buf {
 546                         let om_len = om.serialized_length();
 547                         if pk == peer_node_id {
 548                                 peer_buffered_bytes += om_len;
 549                         }
 550                         total_buffered_bytes += om_len;
 551
 552                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 553                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 554                         {
 555                                 return true
 556                         }
 557                 }
 558         }
 559         false
 560 }
 561
 562 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 563 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 564 where
 565         ES::Target: EntropySource,
 566         NS::Target: NodeSigner,
 567         L::Target: Logger,
 568         MR::Target: MessageRouter,
 569         OMH::Target: OffersMessageHandler,
 570         CMH::Target: CustomOnionMessageHandler,
 571 {
 572         /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
 573         /// soon we'll delegate the onion message to a handler that can generate invoices or send
 574         /// payments.
 575         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
 576                 match peel_onion(
 577                         &*self.node_signer, &self.secp_ctx, &*self.logger, &*self.custom_handler, msg
 578                 ) {
 579                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 580                                 log_trace!(self.logger,
 581                                         "Received an onion message with path_id {:02x?} and {} reply_path",
 582                                                 path_id, if reply_path.is_some() { "a" } else { "no" });
 583                                 let response = match message {
 584                                         OnionMessageContents::Offers(msg) => {
 585                                                 self.offers_handler.handle_message(msg)
 586                                                         .map(|msg| OnionMessageContents::Offers(msg))
 587                                         },
 588                                         OnionMessageContents::Custom(msg) => {
 589                                                 self.custom_handler.handle_custom_message(msg)
 590                                                         .map(|msg| OnionMessageContents::Custom(msg))
 591                                         },
 592                                 };
 593                                 if let Some(response) = response {
 594                                         self.respond_with_onion_message(response, path_id, reply_path);
 595                                 }
 596                         },
 597                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 598                                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 599                                 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
 600                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 601                                         return
 602                                 }
 603
 604                                 #[cfg(fuzzing)]
 605                                 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
 606
 607                                 match pending_per_peer_msgs.entry(next_node_id) {
 608                                         hash_map::Entry::Vacant(_) => {
 609                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 610                                                 return
 611                                         },
 612                                         hash_map::Entry::Occupied(mut e) => {
 613                                                 e.get_mut().push_back(onion_message);
 614                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 615                                         }
 616                                 }
 617                         },
 618                         Err(e) => {
 619                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
 620                         }
 621                 }
 622         }
 623
 624         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 625                 if init.features.supports_onion_messages() {
 626                         let mut peers = self.pending_messages.lock().unwrap();
 627                         peers.insert(their_node_id.clone(), VecDeque::new());
 628                 }
 629                 Ok(())
 630         }
 631
 632         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 633                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 634                 pending_msgs.remove(their_node_id);
 635         }
 636
 637         fn provided_node_features(&self) -> NodeFeatures {
 638                 let mut features = NodeFeatures::empty();
 639                 features.set_onion_messages_optional();
 640                 features
 641         }
 642
 643         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
 644                 let mut features = InitFeatures::empty();
 645                 features.set_onion_messages_optional();
 646                 features
 647         }
 648 }
 649
 650 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageProvider
 651 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 652 where
 653         ES::Target: EntropySource,
 654         NS::Target: NodeSigner,
 655         L::Target: Logger,
 656         MR::Target: MessageRouter,
 657         OMH::Target: OffersMessageHandler,
 658         CMH::Target: CustomOnionMessageHandler,
 659 {
 660         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
 661                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 662                 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
 663                         return msgs.pop_front()
 664                 }
 665                 None
 666         }
 667 }
 668
 669 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
 670 // produces
 671 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 672 /// [`SimpleArcPeerManager`]. See their docs for more details.
 673 ///
 674 /// This is not exported to bindings users as `Arc`s don't make sense in bindings.
 675 ///
 676 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 677 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
 678 pub type SimpleArcOnionMessenger<L> = OnionMessenger<
 679         Arc<KeysManager>,
 680         Arc<KeysManager>,
 681         Arc<L>,
 682         Arc<DefaultMessageRouter>,
 683         IgnoringMessageHandler,
 684         IgnoringMessageHandler
 685 >;
 686
 687 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 688 /// [`SimpleRefPeerManager`]. See their docs for more details.
 689 ///
 690 /// This is not exported to bindings users as general type aliases don't make sense in bindings.
 691 ///
 692 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 693 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
 694 pub type SimpleRefOnionMessenger<'a, 'b, 'c, L> = OnionMessenger<
 695         &'a KeysManager,
 696         &'a KeysManager,
 697         &'b L,
 698         &'c DefaultMessageRouter,
 699         IgnoringMessageHandler,
 700         IgnoringMessageHandler
 701 >;
 702
 703 /// Construct onion packet payloads and keys for sending an onion message along the given
 704 /// `unblinded_path` to the given `destination`.
 705 fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
 706         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
 707         message: OnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 708 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 709         let num_hops = unblinded_path.len() + destination.num_hops();
 710         let mut payloads = Vec::with_capacity(num_hops);
 711         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 712
 713         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
 714                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 715                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 716         let num_unblinded_hops = num_hops - num_blinded_hops;
 717
 718         let mut unblinded_path_idx = 0;
 719         let mut blinded_path_idx = 0;
 720         let mut prev_control_tlvs_ss = None;
 721         let mut final_control_tlvs = None;
 722         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
 723                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
 724                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 725                                 if let Some(ss) = prev_control_tlvs_ss.take() {
 726                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
 727                                                 ForwardTlvs {
 728                                                         next_node_id: unblinded_pk_opt.unwrap(),
 729                                                         next_blinding_override: None,
 730                                                 }
 731                                         )), ss));
 732                                 }
 733                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 734                                 unblinded_path_idx += 1;
 735                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
 736                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
 737                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 738                                                 next_node_id: intro_node_id,
 739                                                 next_blinding_override: Some(blinding_pt),
 740                                         })), control_tlvs_ss));
 741                                 }
 742                         }
 743                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
 744                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
 745                                         control_tlvs_ss));
 746                                 blinded_path_idx += 1;
 747                         } else if let Some(encrypted_payload) = enc_payload_opt {
 748                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
 749                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 750                         }
 751
 752                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
 753                         onion_packet_keys.push(onion_utils::OnionKeys {
 754                                 #[cfg(test)]
 755                                 shared_secret: onion_packet_ss,
 756                                 #[cfg(test)]
 757                                 blinding_factor: [0; 32],
 758                                 ephemeral_pubkey,
 759                                 rho,
 760                                 mu,
 761                         });
 762                 }
 763         )?;
 764
 765         if let Some(control_tlvs) = final_control_tlvs {
 766                 payloads.push((Payload::Receive {
 767                         control_tlvs,
 768                         reply_path: reply_path.take(),
 769                         message,
 770                 }, prev_control_tlvs_ss.unwrap()));
 771         } else {
 772                 payloads.push((Payload::Receive {
 773                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
 774                         reply_path: reply_path.take(),
 775                         message,
 776                 }, prev_control_tlvs_ss.unwrap()));
 777         }
 778
 779         Ok((payloads, onion_packet_keys))
 780 }
 781
 782 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
 783 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, ()> {
 784         // Spec rationale:
 785         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
 786         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
 787         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
 788         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
 789         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
 790                 SMALL_PACKET_HOP_DATA_LEN
 791         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
 792                 BIG_PACKET_HOP_DATA_LEN
 793         } else { return Err(()) };
 794
 795         onion_utils::construct_onion_message_packet::<_, _>(
 796                 payloads, onion_keys, prng_seed, hop_data_len)
 797 }