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