git.bitcoin.ninja Git - rust-lightning/blob - lightning/src/onion_message/messenger.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! LDK sends, receives, and forwards onion messages via this [`OnionMessenger`], which lives here,
  11 //! as well as various types, traits, and utilities that it uses.
  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, IntroductionNode, NextMessageHop, NodeIdLookUp};
  19 use crate::blinded_path::message::{advance_path_by_one, ForwardTlvs, ReceiveTlvs};
  20 use crate::blinded_path::utils;
  21 use crate::events::{Event, EventHandler, EventsProvider};
  22 use crate::sign::{EntropySource, NodeSigner, Recipient};
  23 use crate::ln::features::{InitFeatures, NodeFeatures};
  24 use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler, SocketAddress};
  25 use crate::ln::onion_utils;
  26 use crate::routing::gossip::{NetworkGraph, NodeId, ReadOnlyNetworkGraph};
  27 use super::packet::OnionMessageContents;
  28 use super::packet::ParsedOnionMessageContents;
  29 use super::offers::OffersMessageHandler;
  30 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  31 use crate::util::logger::{Logger, WithContext};
  32 use crate::util::ser::Writeable;
  33
  34 use core::fmt;
  35 use core::ops::Deref;
  36 use crate::io;
  37 use crate::sync::Mutex;
  38 use crate::prelude::*;
  39
  40 #[cfg(not(c_bindings))]
  41 use {
  42         crate::sign::KeysManager,
  43         crate::ln::channelmanager::{SimpleArcChannelManager, SimpleRefChannelManager},
  44         crate::ln::peer_handler::IgnoringMessageHandler,
  45         crate::sync::Arc,
  46 };
  47
  48 pub(super) const MAX_TIMER_TICKS: usize = 2;
  49
  50 /// A sender, receiver and forwarder of [`OnionMessage`]s.
  51 ///
  52 /// # Handling Messages
  53 ///
  54 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
  55 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
  56 /// available handlers are:
  57 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
  58 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
  59 ///
  60 /// # Sending Messages
  61 ///
  62 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
  63 /// a message, the matched handler may return a response message which `OnionMessenger` will send
  64 /// on its behalf.
  65 ///
  66 /// # Example
  67 ///
  68 /// ```
  69 /// # extern crate bitcoin;
  70 /// # use bitcoin::hashes::_export::_core::time::Duration;
  71 /// # use bitcoin::hashes::hex::FromHex;
  72 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey, self};
  73 /// # use lightning::blinded_path::{BlindedPath, EmptyNodeIdLookUp};
  74 /// # use lightning::sign::{EntropySource, KeysManager};
  75 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  76 /// # use lightning::onion_message::messenger::{Destination, MessageRouter, OnionMessagePath, OnionMessenger};
  77 /// # use lightning::onion_message::packet::OnionMessageContents;
  78 /// # use lightning::util::logger::{Logger, Record};
  79 /// # use lightning::util::ser::{Writeable, Writer};
  80 /// # use lightning::io;
  81 /// # use std::sync::Arc;
  82 /// # struct FakeLogger;
  83 /// # impl Logger for FakeLogger {
  84 /// #     fn log(&self, record: Record) { println!("{:?}" , record); }
  85 /// # }
  86 /// # struct FakeMessageRouter {}
  87 /// # impl MessageRouter for FakeMessageRouter {
  88 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  89 /// #         let secp_ctx = Secp256k1::new();
  90 /// #         let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  91 /// #         let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  92 /// #         let hop_node_id2 = hop_node_id1;
  93 /// #         Ok(OnionMessagePath {
  94 /// #             intermediate_nodes: vec![hop_node_id1, hop_node_id2],
  95 /// #             destination,
  96 /// #             first_node_addresses: None,
  97 /// #         })
  98 /// #     }
  99 /// #     fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
 100 /// #         &self, _recipient: PublicKey, _peers: Vec<PublicKey>, _secp_ctx: &Secp256k1<T>
 101 /// #     ) -> Result<Vec<BlindedPath>, ()> {
 102 /// #         unreachable!()
 103 /// #     }
 104 /// # }
 105 /// # let seed = [42u8; 32];
 106 /// # let time = Duration::from_secs(123456);
 107 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
 108 /// # let logger = Arc::new(FakeLogger {});
 109 /// # let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
 110 /// # let secp_ctx = Secp256k1::new();
 111 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
 112 /// # let (hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1);
 113 /// # let destination_node_id = hop_node_id1;
 114 /// # let node_id_lookup = EmptyNodeIdLookUp {};
 115 /// # let message_router = Arc::new(FakeMessageRouter {});
 116 /// # let custom_message_handler = IgnoringMessageHandler {};
 117 /// # let offers_message_handler = IgnoringMessageHandler {};
 118 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
 119 /// // ChannelManager.
 120 /// let onion_messenger = OnionMessenger::new(
 121 ///     &keys_manager, &keys_manager, logger, &node_id_lookup, message_router,
 122 ///     &offers_message_handler, &custom_message_handler
 123 /// );
 124
 125 /// # #[derive(Debug)]
 126 /// # struct YourCustomMessage {}
 127 /// impl Writeable for YourCustomMessage {
 128 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 129 ///             # Ok(())
 130 ///             // Write your custom onion message to `w`
 131 ///     }
 132 /// }
 133 /// impl OnionMessageContents for YourCustomMessage {
 134 ///     fn tlv_type(&self) -> u64 {
 135 ///             # let your_custom_message_type = 42;
 136 ///             your_custom_message_type
 137 ///     }
 138 ///     fn msg_type(&self) -> &'static str { "YourCustomMessageType" }
 139 /// }
 140 /// // Send a custom onion message to a node id.
 141 /// let destination = Destination::Node(destination_node_id);
 142 /// let reply_path = None;
 143 /// # let message = YourCustomMessage {};
 144 /// onion_messenger.send_onion_message(message, destination, reply_path);
 145 ///
 146 /// // Create a blinded path to yourself, for someone to send an onion message to.
 147 /// # let your_node_id = hop_node_id1;
 148 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 149 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 150 ///
 151 /// // Send a custom onion message to a blinded path.
 152 /// let destination = Destination::BlindedPath(blinded_path);
 153 /// let reply_path = None;
 154 /// # let message = YourCustomMessage {};
 155 /// onion_messenger.send_onion_message(message, destination, reply_path);
 156 /// ```
 157 ///
 158 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 159 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 160 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 161 where
 162         ES::Target: EntropySource,
 163         NS::Target: NodeSigner,
 164         L::Target: Logger,
 165         NL::Target: NodeIdLookUp,
 166         MR::Target: MessageRouter,
 167         OMH::Target: OffersMessageHandler,
 168         CMH::Target: CustomOnionMessageHandler,
 169 {
 170         entropy_source: ES,
 171         node_signer: NS,
 172         logger: L,
 173         message_recipients: Mutex<HashMap<PublicKey, OnionMessageRecipient>>,
 174         secp_ctx: Secp256k1<secp256k1::All>,
 175         node_id_lookup: NL,
 176         message_router: MR,
 177         offers_handler: OMH,
 178         custom_handler: CMH,
 179         intercept_messages_for_offline_peers: bool,
 180         pending_events: Mutex<Vec<Event>>,
 181 }
 182
 183 /// [`OnionMessage`]s buffered to be sent.
 184 enum OnionMessageRecipient {
 185         /// Messages for a node connected as a peer.
 186         ConnectedPeer(VecDeque<OnionMessage>),
 187
 188         /// Messages for a node that is not yet connected, which are dropped after [`MAX_TIMER_TICKS`]
 189         /// and tracked here.
 190         PendingConnection(VecDeque<OnionMessage>, Option<Vec<SocketAddress>>, usize),
 191 }
 192
 193 impl OnionMessageRecipient {
 194         fn pending_connection(addresses: Vec<SocketAddress>) -> Self {
 195                 Self::PendingConnection(VecDeque::new(), Some(addresses), 0)
 196         }
 197
 198         fn pending_messages(&self) -> &VecDeque<OnionMessage> {
 199                 match self {
 200                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 201                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 202                 }
 203         }
 204
 205         fn enqueue_message(&mut self, message: OnionMessage) {
 206                 let pending_messages = match self {
 207                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 208                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 209                 };
 210
 211                 pending_messages.push_back(message);
 212         }
 213
 214         fn dequeue_message(&mut self) -> Option<OnionMessage> {
 215                 let pending_messages = match self {
 216                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 217                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => {
 218                                 debug_assert!(false);
 219                                 pending_messages
 220                         },
 221                 };
 222
 223                 pending_messages.pop_front()
 224         }
 225
 226         #[cfg(test)]
 227         fn release_pending_messages(&mut self) -> VecDeque<OnionMessage> {
 228                 let pending_messages = match self {
 229                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 230                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 231                 };
 232
 233                 core::mem::take(pending_messages)
 234         }
 235
 236         fn mark_connected(&mut self) {
 237                 if let OnionMessageRecipient::PendingConnection(pending_messages, _, _) = self {
 238                         let mut new_pending_messages = VecDeque::new();
 239                         core::mem::swap(pending_messages, &mut new_pending_messages);
 240                         *self = OnionMessageRecipient::ConnectedPeer(new_pending_messages);
 241                 }
 242         }
 243
 244         fn is_connected(&self) -> bool {
 245                 match self {
 246                         OnionMessageRecipient::ConnectedPeer(..) => true,
 247                         OnionMessageRecipient::PendingConnection(..) => false,
 248                 }
 249         }
 250 }
 251
 252
 253 /// The `Responder` struct creates an appropriate [`ResponseInstruction`]
 254 /// for responding to a message.
 255 pub struct Responder {
 256         /// The path along which a response can be sent.
 257         reply_path: BlindedPath,
 258         path_id: Option<[u8; 32]>
 259 }
 260
 261 impl Responder {
 262         /// Creates a new [`Responder`] instance with the provided reply path.
 263         fn new(reply_path: BlindedPath, path_id: Option<[u8; 32]>) -> Self {
 264                 Responder {
 265                         reply_path,
 266                         path_id,
 267                 }
 268         }
 269
 270         /// Creates the appropriate [`ResponseInstruction`] for a given response.
 271         pub fn respond<T: OnionMessageContents>(self, response: T) -> ResponseInstruction<T> {
 272                 ResponseInstruction::WithoutReplyPath(OnionMessageResponse {
 273                         message: response,
 274                         reply_path: self.reply_path,
 275                         path_id: self.path_id,
 276                 })
 277         }
 278 }
 279
 280 /// This struct contains the information needed to reply to a received message.
 281 pub struct OnionMessageResponse<T: OnionMessageContents> {
 282         message: T,
 283         reply_path: BlindedPath,
 284         path_id: Option<[u8; 32]>,
 285 }
 286
 287 /// `ResponseInstruction` represents instructions for responding to received messages.
 288 pub enum ResponseInstruction<T: OnionMessageContents> {
 289         /// Indicates that a response should be sent without including a reply path
 290         /// for the recipient to respond back.
 291         WithoutReplyPath(OnionMessageResponse<T>),
 292         /// Indicates that there's no response to send back.
 293         NoResponse,
 294 }
 295
 296 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 297 ///
 298 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 299 /// enqueued for sending.
 300 #[cfg(not(c_bindings))]
 301 pub struct PendingOnionMessage<T: OnionMessageContents> {
 302         /// The message contents to send in an [`OnionMessage`].
 303         pub contents: T,
 304
 305         /// The destination of the message.
 306         pub destination: Destination,
 307
 308         /// A reply path to include in the [`OnionMessage`] for a response.
 309         pub reply_path: Option<BlindedPath>,
 310 }
 311
 312 #[cfg(c_bindings)]
 313 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 314 ///
 315 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 316 /// enqueued for sending.
 317 pub type PendingOnionMessage<T> = (T, Destination, Option<BlindedPath>);
 318
 319 pub(crate) fn new_pending_onion_message<T: OnionMessageContents>(
 320         contents: T, destination: Destination, reply_path: Option<BlindedPath>
 321 ) -> PendingOnionMessage<T> {
 322         #[cfg(not(c_bindings))]
 323         return PendingOnionMessage { contents, destination, reply_path };
 324         #[cfg(c_bindings)]
 325         return (contents, destination, reply_path);
 326 }
 327
 328 /// A trait defining behavior for routing an [`OnionMessage`].
 329 pub trait MessageRouter {
 330         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 331         fn find_path(
 332                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 333         ) -> Result<OnionMessagePath, ()>;
 334
 335         /// Creates [`BlindedPath`]s to the `recipient` node. The nodes in `peers` are assumed to be
 336         /// direct peers with the `recipient`.
 337         fn create_blinded_paths<
 338                 T: secp256k1::Signing + secp256k1::Verification
 339         >(
 340                 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 341         ) -> Result<Vec<BlindedPath>, ()>;
 342 }
 343
 344 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
 345 pub struct DefaultMessageRouter<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref>
 346 where
 347         L::Target: Logger,
 348         ES::Target: EntropySource,
 349 {
 350         network_graph: G,
 351         entropy_source: ES,
 352 }
 353
 354 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> DefaultMessageRouter<G, L, ES>
 355 where
 356         L::Target: Logger,
 357         ES::Target: EntropySource,
 358 {
 359         /// Creates a [`DefaultMessageRouter`] using the given [`NetworkGraph`].
 360         pub fn new(network_graph: G, entropy_source: ES) -> Self {
 361                 Self { network_graph, entropy_source }
 362         }
 363 }
 364
 365 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> MessageRouter for DefaultMessageRouter<G, L, ES>
 366 where
 367         L::Target: Logger,
 368         ES::Target: EntropySource,
 369 {
 370         fn find_path(
 371                 &self, sender: PublicKey, peers: Vec<PublicKey>, mut destination: Destination
 372         ) -> Result<OnionMessagePath, ()> {
 373                 let network_graph = self.network_graph.deref().read_only();
 374                 destination.resolve(&network_graph);
 375
 376                 let first_node = match destination.first_node() {
 377                         Some(first_node) => first_node,
 378                         None => return Err(()),
 379                 };
 380
 381                 if peers.contains(&first_node) || sender == first_node {
 382                         Ok(OnionMessagePath {
 383                                 intermediate_nodes: vec![], destination, first_node_addresses: None
 384                         })
 385                 } else {
 386                         let node_details = network_graph
 387                                 .node(&NodeId::from_pubkey(&first_node))
 388                                 .and_then(|node_info| node_info.announcement_info.as_ref())
 389                                 .map(|announcement_info| (announcement_info.features(), announcement_info.addresses()));
 390
 391                         match node_details {
 392                                 Some((features, addresses)) if features.supports_onion_messages() && addresses.len() > 0 => {
 393                                         let first_node_addresses = Some(addresses.clone());
 394                                         Ok(OnionMessagePath {
 395                                                 intermediate_nodes: vec![], destination, first_node_addresses
 396                                         })
 397                                 },
 398                                 _ => Err(()),
 399                         }
 400                 }
 401         }
 402
 403         fn create_blinded_paths<
 404                 T: secp256k1::Signing + secp256k1::Verification
 405         >(
 406                 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 407         ) -> Result<Vec<BlindedPath>, ()> {
 408                 // Limit the number of blinded paths that are computed.
 409                 const MAX_PATHS: usize = 3;
 410
 411                 // Ensure peers have at least three channels so that it is more difficult to infer the
 412                 // recipient's node_id.
 413                 const MIN_PEER_CHANNELS: usize = 3;
 414
 415                 let network_graph = self.network_graph.deref().read_only();
 416                 let is_recipient_announced =
 417                         network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient));
 418
 419                 let mut peer_info = peers.iter()
 420                         // Limit to peers with announced channels
 421                         .filter_map(|pubkey|
 422                                 network_graph
 423                                         .node(&NodeId::from_pubkey(pubkey))
 424                                         .filter(|info| info.channels.len() >= MIN_PEER_CHANNELS)
 425                                         .map(|info| (*pubkey, info.is_tor_only(), info.channels.len()))
 426                         )
 427                         // Exclude Tor-only nodes when the recipient is announced.
 428                         .filter(|(_, is_tor_only, _)| !(*is_tor_only && is_recipient_announced))
 429                         .collect::<Vec<_>>();
 430
 431                 // Prefer using non-Tor nodes with the most channels as the introduction node.
 432                 peer_info.sort_unstable_by(|(_, a_tor_only, a_channels), (_, b_tor_only, b_channels)| {
 433                         a_tor_only.cmp(b_tor_only).then(a_channels.cmp(b_channels).reverse())
 434                 });
 435
 436                 let paths = peer_info.into_iter()
 437                         .map(|(pubkey, _, _)| vec![pubkey, recipient])
 438                         .map(|node_pks| BlindedPath::new_for_message(&node_pks, &*self.entropy_source, secp_ctx))
 439                         .take(MAX_PATHS)
 440                         .collect::<Result<Vec<_>, _>>();
 441
 442                 match paths {
 443                         Ok(paths) if !paths.is_empty() => Ok(paths),
 444                         _ => {
 445                                 if is_recipient_announced {
 446                                         BlindedPath::one_hop_for_message(recipient, &*self.entropy_source, secp_ctx)
 447                                                 .map(|path| vec![path])
 448                                 } else {
 449                                         Err(())
 450                                 }
 451                         },
 452                 }
 453         }
 454 }
 455
 456 /// A path for sending an [`OnionMessage`].
 457 #[derive(Clone)]
 458 pub struct OnionMessagePath {
 459         /// Nodes on the path between the sender and the destination.
 460         pub intermediate_nodes: Vec<PublicKey>,
 461
 462         /// The recipient of the message.
 463         pub destination: Destination,
 464
 465         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 466         ///
 467         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 468         /// this to initiate such a connection.
 469         pub first_node_addresses: Option<Vec<SocketAddress>>,
 470 }
 471
 472 impl OnionMessagePath {
 473         /// Returns the first node in the path.
 474         pub fn first_node(&self) -> Option<PublicKey> {
 475                 self.intermediate_nodes
 476                         .first()
 477                         .copied()
 478                         .or_else(|| self.destination.first_node())
 479         }
 480 }
 481
 482 /// The destination of an onion message.
 483 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 484 pub enum Destination {
 485         /// We're sending this onion message to a node.
 486         Node(PublicKey),
 487         /// We're sending this onion message to a blinded path.
 488         BlindedPath(BlindedPath),
 489 }
 490
 491 impl Destination {
 492         /// Attempts to resolve the [`IntroductionNode::DirectedShortChannelId`] of a
 493         /// [`Destination::BlindedPath`] to a [`IntroductionNode::NodeId`], if applicable, using the
 494         /// provided [`ReadOnlyNetworkGraph`].
 495         pub fn resolve(&mut self, network_graph: &ReadOnlyNetworkGraph) {
 496                 if let Destination::BlindedPath(path) = self {
 497                         if let IntroductionNode::DirectedShortChannelId(..) = path.introduction_node {
 498                                 if let Some(pubkey) = path
 499                                         .public_introduction_node_id(network_graph)
 500                                         .and_then(|node_id| node_id.as_pubkey().ok())
 501                                 {
 502                                         path.introduction_node = IntroductionNode::NodeId(pubkey);
 503                                 }
 504                         }
 505                 }
 506         }
 507
 508         pub(super) fn num_hops(&self) -> usize {
 509                 match self {
 510                         Destination::Node(_) => 1,
 511                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 512                 }
 513         }
 514
 515         fn first_node(&self) -> Option<PublicKey> {
 516                 match self {
 517                         Destination::Node(node_id) => Some(*node_id),
 518                         Destination::BlindedPath(BlindedPath { introduction_node, .. }) => {
 519                                 match introduction_node {
 520                                         IntroductionNode::NodeId(pubkey) => Some(*pubkey),
 521                                         IntroductionNode::DirectedShortChannelId(..) => None,
 522                                 }
 523                         },
 524                 }
 525         }
 526 }
 527
 528 /// Result of successfully [sending an onion message].
 529 ///
 530 /// [sending an onion message]: OnionMessenger::send_onion_message
 531 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 532 pub enum SendSuccess {
 533         /// The message was buffered and will be sent once it is processed by
 534         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 535         Buffered,
 536         /// The message was buffered and will be sent once the node is connected as a peer and it is
 537         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 538         BufferedAwaitingConnection(PublicKey),
 539 }
 540
 541 /// Errors that may occur when [sending an onion message].
 542 ///
 543 /// [sending an onion message]: OnionMessenger::send_onion_message
 544 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 545 pub enum SendError {
 546         /// Errored computing onion message packet keys.
 547         Secp256k1(secp256k1::Error),
 548         /// Because implementations such as Eclair will drop onion messages where the message packet
 549         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 550         TooBigPacket,
 551         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 552         /// hops.
 553         TooFewBlindedHops,
 554         /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
 555         InvalidFirstHop(PublicKey),
 556         /// A path from the sender to the destination could not be found by the [`MessageRouter`].
 557         PathNotFound,
 558         /// Onion message contents must have a TLV type >= 64.
 559         InvalidMessage,
 560         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 561         BufferFull,
 562         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 563         ///
 564         /// [`NodeSigner`]: crate::sign::NodeSigner
 565         GetNodeIdFailed,
 566         /// The provided [`Destination`] has a blinded path with an unresolved introduction node. An
 567         /// attempt to resolve it in the [`MessageRouter`] when finding an [`OnionMessagePath`] likely
 568         /// failed.
 569         UnresolvedIntroductionNode,
 570         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 571         /// advance the blinded path to make the second hop the new introduction node. Either
 572         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 573         /// new blinding point, or we were attempting to send to ourselves.
 574         BlindedPathAdvanceFailed,
 575 }
 576
 577 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 578 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 579 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 580 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 581 /// message types.
 582 ///
 583 /// See [`OnionMessenger`] for example usage.
 584 ///
 585 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 586 /// [`CustomMessage`]: Self::CustomMessage
 587 pub trait CustomOnionMessageHandler {
 588         /// The message known to the handler. To support multiple message types, you may want to make this
 589         /// an enum with a variant for each supported message.
 590         type CustomMessage: OnionMessageContents;
 591
 592         /// Called with the custom message that was received, returning a response to send, if any.
 593         ///
 594         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 595         fn handle_custom_message(&self, message: Self::CustomMessage, responder: Option<Responder>) -> ResponseInstruction<Self::CustomMessage>;
 596
 597         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 598         /// message type is unknown.
 599         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 600
 601         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 602         ///
 603         /// Typically, this is used for messages initiating a message flow rather than in response to
 604         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 605         #[cfg(not(c_bindings))]
 606         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 607
 608         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 609         ///
 610         /// Typically, this is used for messages initiating a message flow rather than in response to
 611         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 612         #[cfg(c_bindings)]
 613         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 614 }
 615
 616 /// A processed incoming onion message, containing either a Forward (another onion message)
 617 /// or a Receive payload with decrypted contents.
 618 #[derive(Clone, Debug)]
 619 pub enum PeeledOnion<T: OnionMessageContents> {
 620         /// Forwarded onion, with the next node id and a new onion
 621         Forward(NextMessageHop, OnionMessage),
 622         /// Received onion message, with decrypted contents, path_id, and reply path
 623         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 624 }
 625
 626
 627 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 628 /// `path`, first calling [`Destination::resolve`] on `path.destination` with the given
 629 /// [`ReadOnlyNetworkGraph`].
 630 ///
 631 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 632 /// needed to connect to the first node.
 633 pub fn create_onion_message_resolving_destination<
 634         ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents
 635 >(
 636         entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
 637         network_graph: &ReadOnlyNetworkGraph, secp_ctx: &Secp256k1<secp256k1::All>,
 638         mut path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 639 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 640 where
 641         ES::Target: EntropySource,
 642         NS::Target: NodeSigner,
 643         NL::Target: NodeIdLookUp,
 644 {
 645         path.destination.resolve(network_graph);
 646         create_onion_message(
 647                 entropy_source, node_signer, node_id_lookup, secp_ctx, path, contents, reply_path,
 648         )
 649 }
 650
 651 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 652 /// `path`.
 653 ///
 654 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 655 /// needed to connect to the first node.
 656 ///
 657 /// Returns [`SendError::UnresolvedIntroductionNode`] if:
 658 /// - `destination` contains a blinded path with an [`IntroductionNode::DirectedShortChannelId`],
 659 /// - unless it can be resolved by [`NodeIdLookUp::next_node_id`].
 660 /// Use [`create_onion_message_resolving_destination`] instead to resolve the introduction node
 661 /// first with a [`ReadOnlyNetworkGraph`].
 662 pub fn create_onion_message<ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents>(
 663         entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
 664         secp_ctx: &Secp256k1<secp256k1::All>, path: OnionMessagePath, contents: T,
 665         reply_path: Option<BlindedPath>,
 666 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 667 where
 668         ES::Target: EntropySource,
 669         NS::Target: NodeSigner,
 670         NL::Target: NodeIdLookUp,
 671 {
 672         let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
 673         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 674                 if blinded_hops.is_empty() {
 675                         return Err(SendError::TooFewBlindedHops);
 676                 }
 677         }
 678
 679         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 680
 681         // If we are sending straight to a blinded path and we are the introduction node, we need to
 682         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 683         if intermediate_nodes.len() == 0 {
 684                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 685                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 686                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 687                         let introduction_node_id = match blinded_path.introduction_node {
 688                                 IntroductionNode::NodeId(pubkey) => pubkey,
 689                                 IntroductionNode::DirectedShortChannelId(direction, scid) => {
 690                                         match node_id_lookup.next_node_id(scid) {
 691                                                 Some(next_node_id) => *direction.select_pubkey(&our_node_id, &next_node_id),
 692                                                 None => return Err(SendError::UnresolvedIntroductionNode),
 693                                         }
 694                                 },
 695                         };
 696                         if introduction_node_id == our_node_id {
 697                                 advance_path_by_one(blinded_path, node_signer, node_id_lookup, &secp_ctx)
 698                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 699                         }
 700                 }
 701         }
 702
 703         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 704         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 705         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 706                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 707         } else {
 708                 match &destination {
 709                         Destination::Node(pk) => (*pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 710                         Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, .. }) => {
 711                                 match introduction_node {
 712                                         IntroductionNode::NodeId(pubkey) => (*pubkey, *blinding_point),
 713                                         IntroductionNode::DirectedShortChannelId(..) => {
 714                                                 return Err(SendError::UnresolvedIntroductionNode);
 715                                         },
 716                                 }
 717                         }
 718                 }
 719         };
 720         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 721                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret
 722         )?;
 723
 724         let prng_seed = entropy_source.get_secure_random_bytes();
 725         let onion_routing_packet = construct_onion_message_packet(
 726                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 727
 728         let message = OnionMessage { blinding_point, onion_routing_packet };
 729         Ok((first_node_id, message, first_node_addresses))
 730 }
 731
 732 /// Decode one layer of an incoming [`OnionMessage`].
 733 ///
 734 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 735 /// receiver.
 736 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 737         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 738         custom_handler: CMH,
 739 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 740 where
 741         NS::Target: NodeSigner,
 742         L::Target: Logger,
 743         CMH::Target: CustomOnionMessageHandler,
 744 {
 745         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 746                 Ok(ss) => ss,
 747                 Err(e) =>  {
 748                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 749                         return Err(());
 750                 }
 751         };
 752         let onion_decode_ss = {
 753                 let blinding_factor = {
 754                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 755                         hmac.input(control_tlvs_ss.as_ref());
 756                         Hmac::from_engine(hmac).to_byte_array()
 757                 };
 758                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 759                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 760                 {
 761                         Ok(ss) => ss.secret_bytes(),
 762                         Err(()) => {
 763                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 764                                 return Err(());
 765                         }
 766                 }
 767         };
 768         match onion_utils::decode_next_untagged_hop(
 769                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 770                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 771         ) {
 772                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 773                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 774                 }, None)) => {
 775                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 776                 },
 777                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 778                         next_hop, next_blinding_override
 779                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 780                         // TODO: we need to check whether `next_hop` is our node, in which case this is a dummy
 781                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 782                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 783                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 784                         // for now.
 785                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 786                                 Ok(pk) => pk,
 787                                 Err(e) => {
 788                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 789                                         return Err(())
 790                                 }
 791                         };
 792                         let outgoing_packet = Packet {
 793                                 version: 0,
 794                                 public_key: new_pubkey,
 795                                 hop_data: new_packet_bytes,
 796                                 hmac: next_hop_hmac,
 797                         };
 798                         let onion_message = OnionMessage {
 799                                 blinding_point: match next_blinding_override {
 800                                         Some(blinding_point) => blinding_point,
 801                                         None => {
 802                                                 match onion_utils::next_hop_pubkey(
 803                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 804                                                 ) {
 805                                                         Ok(bp) => bp,
 806                                                         Err(e) => {
 807                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 808                                                                 return Err(())
 809                                                         }
 810                                                 }
 811                                         }
 812                                 },
 813                                 onion_routing_packet: outgoing_packet,
 814                         };
 815
 816                         Ok(PeeledOnion::Forward(next_hop, onion_message))
 817                 },
 818                 Err(e) => {
 819                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 820                         Err(())
 821                 },
 822                 _ => {
 823                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 824                         Err(())
 825                 },
 826         }
 827 }
 828
 829 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 830 OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
 831 where
 832         ES::Target: EntropySource,
 833         NS::Target: NodeSigner,
 834         L::Target: Logger,
 835         NL::Target: NodeIdLookUp,
 836         MR::Target: MessageRouter,
 837         OMH::Target: OffersMessageHandler,
 838         CMH::Target: CustomOnionMessageHandler,
 839 {
 840         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 841         /// their respective handlers.
 842         pub fn new(
 843                 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL, message_router: MR,
 844                 offers_handler: OMH, custom_handler: CMH
 845         ) -> Self {
 846                 Self::new_inner(
 847                         entropy_source, node_signer, logger, node_id_lookup, message_router,
 848                         offers_handler, custom_handler, false
 849                 )
 850         }
 851
 852         /// Similar to [`Self::new`], but rather than dropping onion messages that are
 853         /// intended to be forwarded to offline peers, we will intercept them for
 854         /// later forwarding.
 855         ///
 856         /// Interception flow:
 857         /// 1. If an onion message for an offline peer is received, `OnionMessenger` will
 858         ///    generate an [`Event::OnionMessageIntercepted`]. Event handlers can
 859         ///    then choose to persist this onion message for later forwarding, or drop
 860         ///    it.
 861         /// 2. When the offline peer later comes back online, `OnionMessenger` will
 862         ///    generate an [`Event::OnionMessagePeerConnected`]. Event handlers will
 863         ///    then fetch all previously intercepted onion messages for this peer.
 864         /// 3. Once the stored onion messages are fetched, they can finally be
 865         ///    forwarded to the now-online peer via [`Self::forward_onion_message`].
 866         ///
 867         /// # Note
 868         ///
 869         /// LDK will not rate limit how many [`Event::OnionMessageIntercepted`]s
 870         /// are generated, so it is the caller's responsibility to limit how many
 871         /// onion messages are persisted and only persist onion messages for relevant
 872         /// peers.
 873         pub fn new_with_offline_peer_interception(
 874                 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL,
 875                 message_router: MR, offers_handler: OMH, custom_handler: CMH
 876         ) -> Self {
 877                 Self::new_inner(
 878                         entropy_source, node_signer, logger, node_id_lookup, message_router,
 879                         offers_handler, custom_handler, true
 880                 )
 881         }
 882
 883         fn new_inner(
 884                 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL,
 885                 message_router: MR, offers_handler: OMH, custom_handler: CMH,
 886                 intercept_messages_for_offline_peers: bool
 887         ) -> Self {
 888                 let mut secp_ctx = Secp256k1::new();
 889                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 890                 OnionMessenger {
 891                         entropy_source,
 892                         node_signer,
 893                         message_recipients: Mutex::new(new_hash_map()),
 894                         secp_ctx,
 895                         logger,
 896                         node_id_lookup,
 897                         message_router,
 898                         offers_handler,
 899                         custom_handler,
 900                         intercept_messages_for_offline_peers,
 901                         pending_events: Mutex::new(Vec::new()),
 902                 }
 903         }
 904
 905         #[cfg(test)]
 906         pub(crate) fn set_offers_handler(&mut self, offers_handler: OMH) {
 907                 self.offers_handler = offers_handler;
 908         }
 909
 910         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
 911         ///
 912         /// See [`OnionMessenger`] for example usage.
 913         pub fn send_onion_message<T: OnionMessageContents>(
 914                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
 915         ) -> Result<SendSuccess, SendError> {
 916                 self.find_path_and_enqueue_onion_message(
 917                         contents, destination, reply_path, format_args!("")
 918                 )
 919         }
 920
 921         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 922                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 923                 log_suffix: fmt::Arguments
 924         ) -> Result<SendSuccess, SendError> {
 925                 let mut logger = WithContext::from(&self.logger, None, None, None);
 926                 let result = self.find_path(destination).and_then(|path| {
 927                         let first_hop = path.intermediate_nodes.get(0).map(|p| *p);
 928                         logger = WithContext::from(&self.logger, first_hop, None, None);
 929                         self.enqueue_onion_message(path, contents, reply_path, log_suffix)
 930                 });
 931
 932                 match result.as_ref() {
 933                         Err(SendError::GetNodeIdFailed) => {
 934                                 log_warn!(logger, "Unable to retrieve node id {}", log_suffix);
 935                         },
 936                         Err(SendError::PathNotFound) => {
 937                                 log_trace!(logger, "Failed to find path {}", log_suffix);
 938                         },
 939                         Err(e) => {
 940                                 log_trace!(logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 941                         },
 942                         Ok(SendSuccess::Buffered) => {
 943                                 log_trace!(logger, "Buffered onion message {}", log_suffix);
 944                         },
 945                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
 946                                 log_trace!(
 947                                         logger,
 948                                         "Buffered onion message waiting on peer connection {}: {}",
 949                                         log_suffix, node_id
 950                                 );
 951                         },
 952                 }
 953
 954                 result
 955         }
 956
 957         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
 958                 let sender = self.node_signer
 959                         .get_node_id(Recipient::Node)
 960                         .map_err(|_| SendError::GetNodeIdFailed)?;
 961
 962                 let peers = self.message_recipients.lock().unwrap()
 963                         .iter()
 964                         .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
 965                         .map(|(node_id, _)| *node_id)
 966                         .collect();
 967
 968                 self.message_router
 969                         .find_path(sender, peers, destination)
 970                         .map_err(|_| SendError::PathNotFound)
 971         }
 972
 973         fn enqueue_onion_message<T: OnionMessageContents>(
 974                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 975                 log_suffix: fmt::Arguments
 976         ) -> Result<SendSuccess, SendError> {
 977                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 978
 979                 let (first_node_id, onion_message, addresses) = create_onion_message(
 980                         &self.entropy_source, &self.node_signer, &self.node_id_lookup, &self.secp_ctx, path,
 981                         contents, reply_path,
 982                 )?;
 983
 984                 let mut message_recipients = self.message_recipients.lock().unwrap();
 985                 if outbound_buffer_full(&first_node_id, &message_recipients) {
 986                         return Err(SendError::BufferFull);
 987                 }
 988
 989                 match message_recipients.entry(first_node_id) {
 990                         hash_map::Entry::Vacant(e) => match addresses {
 991                                 None => Err(SendError::InvalidFirstHop(first_node_id)),
 992                                 Some(addresses) => {
 993                                         e.insert(OnionMessageRecipient::pending_connection(addresses))
 994                                                 .enqueue_message(onion_message);
 995                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 996                                 },
 997                         },
 998                         hash_map::Entry::Occupied(mut e) => {
 999                                 e.get_mut().enqueue_message(onion_message);
1000                                 if e.get().is_connected() {
1001                                         Ok(SendSuccess::Buffered)
1002                                 } else {
1003                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
1004                                 }
1005                         },
1006                 }
1007         }
1008
1009         /// Forwards an [`OnionMessage`] to `peer_node_id`. Useful if we initialized
1010         /// the [`OnionMessenger`] with [`Self::new_with_offline_peer_interception`]
1011         /// and want to forward a previously intercepted onion message to a peer that
1012         /// has just come online.
1013         pub fn forward_onion_message(
1014                 &self, message: OnionMessage, peer_node_id: &PublicKey
1015         ) -> Result<(), SendError> {
1016                 let mut message_recipients = self.message_recipients.lock().unwrap();
1017                 if outbound_buffer_full(&peer_node_id, &message_recipients) {
1018                         return Err(SendError::BufferFull);
1019                 }
1020
1021                 match message_recipients.entry(*peer_node_id) {
1022                         hash_map::Entry::Occupied(mut e) if e.get().is_connected() => {
1023                                 e.get_mut().enqueue_message(message);
1024                                 Ok(())
1025                         },
1026                         _ => Err(SendError::InvalidFirstHop(*peer_node_id))
1027                 }
1028         }
1029
1030         #[cfg(any(test, feature = "_test_utils"))]
1031         pub fn send_onion_message_using_path<T: OnionMessageContents>(
1032                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
1033         ) -> Result<SendSuccess, SendError> {
1034                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
1035         }
1036
1037         pub(crate) fn peel_onion_message(
1038                 &self, msg: &OnionMessage
1039         ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()> {
1040                 peel_onion_message(
1041                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
1042                 )
1043         }
1044
1045         fn handle_onion_message_response<T: OnionMessageContents>(
1046                 &self, response: ResponseInstruction<T>
1047         ) {
1048                 if let ResponseInstruction::WithoutReplyPath(response) = response {
1049                         let message_type = response.message.msg_type();
1050                         let _ = self.find_path_and_enqueue_onion_message(
1051                                 response.message, Destination::BlindedPath(response.reply_path), None,
1052                                 format_args!(
1053                                         "when responding with {} to an onion message with path_id {:02x?}",
1054                                         message_type,
1055                                         response.path_id
1056                                 )
1057                         );
1058                 }
1059         }
1060
1061         #[cfg(test)]
1062         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
1063                 let mut message_recipients = self.message_recipients.lock().unwrap();
1064                 let mut msgs = new_hash_map();
1065                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
1066                 // release the pending message buffers individually.
1067                 for (node_id, recipient) in &mut *message_recipients {
1068                         msgs.insert(*node_id, recipient.release_pending_messages());
1069                 }
1070                 msgs
1071         }
1072
1073         fn enqueue_event(&self, event: Event) {
1074                 const MAX_EVENTS_BUFFER_SIZE: usize = (1 << 10) * 256;
1075                 let mut pending_events = self.pending_events.lock().unwrap();
1076                 let total_buffered_bytes: usize = pending_events
1077                         .iter()
1078                         .map(|ev| ev.serialized_length())
1079                         .sum();
1080                 if total_buffered_bytes >= MAX_EVENTS_BUFFER_SIZE {
1081                         log_trace!(self.logger, "Dropping event {:?}: buffer full", event);
1082                         return
1083                 }
1084                 pending_events.push(event);
1085         }
1086 }
1087
1088 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
1089         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
1090         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
1091         let mut total_buffered_bytes = 0;
1092         let mut peer_buffered_bytes = 0;
1093         for (pk, peer_buf) in buffer {
1094                 for om in peer_buf.pending_messages() {
1095                         let om_len = om.serialized_length();
1096                         if pk == peer_node_id {
1097                                 peer_buffered_bytes += om_len;
1098                         }
1099                         total_buffered_bytes += om_len;
1100
1101                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
1102                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
1103                         {
1104                                 return true
1105                         }
1106                 }
1107         }
1108         false
1109 }
1110
1111 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
1112 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
1113 where
1114         ES::Target: EntropySource,
1115         NS::Target: NodeSigner,
1116         L::Target: Logger,
1117         NL::Target: NodeIdLookUp,
1118         MR::Target: MessageRouter,
1119         OMH::Target: OffersMessageHandler,
1120         CMH::Target: CustomOnionMessageHandler,
1121 {
1122         fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
1123                 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
1124                         if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
1125                                 if let Some(addresses) = addresses.take() {
1126                                         handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
1127                                 }
1128                         }
1129                 }
1130                 let mut events = Vec::new();
1131                 core::mem::swap(&mut *self.pending_events.lock().unwrap(), &mut events);
1132                 for ev in events {
1133                         handler.handle_event(ev);
1134                 }
1135         }
1136 }
1137
1138 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
1139 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
1140 where
1141         ES::Target: EntropySource,
1142         NS::Target: NodeSigner,
1143         L::Target: Logger,
1144         NL::Target: NodeIdLookUp,
1145         MR::Target: MessageRouter,
1146         OMH::Target: OffersMessageHandler,
1147         CMH::Target: CustomOnionMessageHandler,
1148 {
1149         fn handle_onion_message(&self, peer_node_id: &PublicKey, msg: &OnionMessage) {
1150                 let logger = WithContext::from(&self.logger, Some(*peer_node_id), None, None);
1151                 match self.peel_onion_message(msg) {
1152                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
1153                                 log_trace!(
1154                                         logger,
1155                                         "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
1156                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
1157
1158                                 match message {
1159                                         ParsedOnionMessageContents::Offers(msg) => {
1160                                                 let responder = reply_path.map(
1161                                                         |reply_path| Responder::new(reply_path, path_id)
1162                                                 );
1163                                                 let response_instructions = self.offers_handler.handle_message(msg, responder);
1164                                                 self.handle_onion_message_response(response_instructions);
1165                                         },
1166                                         ParsedOnionMessageContents::Custom(msg) => {
1167                                                 let responder = reply_path.map(
1168                                                         |reply_path| Responder::new(reply_path, path_id)
1169                                                 );
1170                                                 let response_instructions = self.custom_handler.handle_custom_message(msg, responder);
1171                                                 self.handle_onion_message_response(response_instructions);
1172                                         },
1173                                 }
1174                         },
1175                         Ok(PeeledOnion::Forward(next_hop, onion_message)) => {
1176                                 let next_node_id = match next_hop {
1177                                         NextMessageHop::NodeId(pubkey) => pubkey,
1178                                         NextMessageHop::ShortChannelId(scid) => match self.node_id_lookup.next_node_id(scid) {
1179                                                 Some(pubkey) => pubkey,
1180                                                 None => {
1181                                                         log_trace!(self.logger, "Dropping forwarded onion messager: unable to resolve next hop using SCID {}", scid);
1182                                                         return
1183                                                 },
1184                                         },
1185                                 };
1186
1187                                 let mut message_recipients = self.message_recipients.lock().unwrap();
1188                                 if outbound_buffer_full(&next_node_id, &message_recipients) {
1189                                         log_trace!(
1190                                                 logger,
1191                                                 "Dropping forwarded onion message to peer {}: outbound buffer full",
1192                                                 next_node_id);
1193                                         return
1194                                 }
1195
1196                                 #[cfg(fuzzing)]
1197                                 message_recipients
1198                                         .entry(next_node_id)
1199                                         .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
1200
1201                                 match message_recipients.entry(next_node_id) {
1202                                         hash_map::Entry::Occupied(mut e) if matches!(
1203                                                 e.get(), OnionMessageRecipient::ConnectedPeer(..)
1204                                         ) => {
1205                                                 e.get_mut().enqueue_message(onion_message);
1206                                                 log_trace!(logger, "Forwarding an onion message to peer {}", next_node_id);
1207                                         },
1208                                         _ if self.intercept_messages_for_offline_peers => {
1209                                                 self.enqueue_event(
1210                                                         Event::OnionMessageIntercepted {
1211                                                                 peer_node_id: next_node_id, message: onion_message
1212                                                         }
1213                                                 );
1214                                         },
1215                                         _ => {
1216                                                 log_trace!(
1217                                                         logger,
1218                                                         "Dropping forwarded onion message to disconnected peer {}",
1219                                                         next_node_id);
1220                                                 return
1221                                         },
1222                                 }
1223                         },
1224                         Err(e) => {
1225                                 log_error!(logger, "Failed to process onion message {:?}", e);
1226                         }
1227                 }
1228         }
1229
1230         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
1231                 if init.features.supports_onion_messages() {
1232                         self.message_recipients.lock().unwrap()
1233                                 .entry(*their_node_id)
1234                                 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
1235                                 .mark_connected();
1236                         if self.intercept_messages_for_offline_peers {
1237                                 self.enqueue_event(
1238                                         Event::OnionMessagePeerConnected { peer_node_id: *their_node_id }
1239                                 );
1240                         }
1241                 } else {
1242                         self.message_recipients.lock().unwrap().remove(their_node_id);
1243                 }
1244
1245                 Ok(())
1246         }
1247
1248         fn peer_disconnected(&self, their_node_id: &PublicKey) {
1249                 match self.message_recipients.lock().unwrap().remove(their_node_id) {
1250                         Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
1251                         Some(_) => debug_assert!(false),
1252                         None => {},
1253                 }
1254         }
1255
1256         fn timer_tick_occurred(&self) {
1257                 let mut message_recipients = self.message_recipients.lock().unwrap();
1258
1259                 // Drop any pending recipients since the last call to avoid retaining buffered messages for
1260                 // too long.
1261                 message_recipients.retain(|_, recipient| match recipient {
1262                         OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
1263                         OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
1264                         _ => true,
1265                 });
1266
1267                 // Increment a timer tick for pending recipients so that their buffered messages are dropped
1268                 // at MAX_TIMER_TICKS.
1269                 for recipient in message_recipients.values_mut() {
1270                         if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
1271                                 *ticks += 1;
1272                         }
1273                 }
1274         }
1275
1276         fn provided_node_features(&self) -> NodeFeatures {
1277                 let mut features = NodeFeatures::empty();
1278                 features.set_onion_messages_optional();
1279                 features
1280         }
1281
1282         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1283                 let mut features = InitFeatures::empty();
1284                 features.set_onion_messages_optional();
1285                 features
1286         }
1287
1288         // Before returning any messages to send for the peer, this method will see if any messages were
1289         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1290         // node, and then enqueue the message for sending to the first peer in the full path.
1291         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1292                 // Enqueue any initiating `OffersMessage`s to send.
1293                 for message in self.offers_handler.release_pending_messages() {
1294                         #[cfg(not(c_bindings))]
1295                         let PendingOnionMessage { contents, destination, reply_path } = message;
1296                         #[cfg(c_bindings)]
1297                         let (contents, destination, reply_path) = message;
1298                         let _ = self.find_path_and_enqueue_onion_message(
1299                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
1300                         );
1301                 }
1302
1303                 // Enqueue any initiating `CustomMessage`s to send.
1304                 for message in self.custom_handler.release_pending_custom_messages() {
1305                         #[cfg(not(c_bindings))]
1306                         let PendingOnionMessage { contents, destination, reply_path } = message;
1307                         #[cfg(c_bindings)]
1308                         let (contents, destination, reply_path) = message;
1309                         let _ = self.find_path_and_enqueue_onion_message(
1310                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
1311                         );
1312                 }
1313
1314                 self.message_recipients.lock().unwrap()
1315                         .get_mut(&peer_node_id)
1316                         .and_then(|buffer| buffer.dequeue_message())
1317         }
1318 }
1319
1320 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1321 // produces
1322 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1323 /// [`SimpleArcPeerManager`]. See their docs for more details.
1324 ///
1325 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1326 ///
1327 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1328 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1329 #[cfg(not(c_bindings))]
1330 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1331         Arc<KeysManager>,
1332         Arc<KeysManager>,
1333         Arc<L>,
1334         Arc<SimpleArcChannelManager<M, T, F, L>>,
1335         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>, Arc<KeysManager>>>,
1336         Arc<SimpleArcChannelManager<M, T, F, L>>,
1337         IgnoringMessageHandler
1338 >;
1339
1340 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1341 /// [`SimpleRefPeerManager`]. See their docs for more details.
1342 ///
1343 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1344 ///
1345 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1346 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1347 #[cfg(not(c_bindings))]
1348 pub type SimpleRefOnionMessenger<
1349         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1350 > = OnionMessenger<
1351         &'a KeysManager,
1352         &'a KeysManager,
1353         &'b L,
1354         &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1355         &'j DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L, &'a KeysManager>,
1356         &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1357         IgnoringMessageHandler
1358 >;
1359
1360 /// Construct onion packet payloads and keys for sending an onion message along the given
1361 /// `unblinded_path` to the given `destination`.
1362 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1363         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1364         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1365 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), SendError> {
1366         let num_hops = unblinded_path.len() + destination.num_hops();
1367         let mut payloads = Vec::with_capacity(num_hops);
1368         let mut onion_packet_keys = Vec::with_capacity(num_hops);
1369
1370         let (mut intro_node_id_blinding_pt, num_blinded_hops) = match &destination {
1371                 Destination::Node(_) => (None, 0),
1372                 Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, blinded_hops }) => {
1373                         let introduction_node_id = match introduction_node {
1374                                 IntroductionNode::NodeId(pubkey) => pubkey,
1375                                 IntroductionNode::DirectedShortChannelId(..) => {
1376                                         return Err(SendError::UnresolvedIntroductionNode);
1377                                 },
1378                         };
1379                         (Some((*introduction_node_id, *blinding_point)), blinded_hops.len())
1380                 },
1381         };
1382         let num_unblinded_hops = num_hops - num_blinded_hops;
1383
1384         let mut unblinded_path_idx = 0;
1385         let mut blinded_path_idx = 0;
1386         let mut prev_control_tlvs_ss = None;
1387         let mut final_control_tlvs = None;
1388         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1389                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1390                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1391                                 if let Some(ss) = prev_control_tlvs_ss.take() {
1392                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1393                                                 ForwardTlvs {
1394                                                         next_hop: NextMessageHop::NodeId(unblinded_pk_opt.unwrap()),
1395                                                         next_blinding_override: None,
1396                                                 }
1397                                         )), ss));
1398                                 }
1399                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1400                                 unblinded_path_idx += 1;
1401                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1402                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1403                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1404                                                 next_hop: NextMessageHop::NodeId(intro_node_id),
1405                                                 next_blinding_override: Some(blinding_pt),
1406                                         })), control_tlvs_ss));
1407                                 }
1408                         }
1409                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1410                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1411                                         control_tlvs_ss));
1412                                 blinded_path_idx += 1;
1413                         } else if let Some(encrypted_payload) = enc_payload_opt {
1414                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1415                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1416                         }
1417
1418                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1419                         onion_packet_keys.push(onion_utils::OnionKeys {
1420                                 #[cfg(test)]
1421                                 shared_secret: onion_packet_ss,
1422                                 #[cfg(test)]
1423                                 blinding_factor: [0; 32],
1424                                 ephemeral_pubkey,
1425                                 rho,
1426                                 mu,
1427                         });
1428                 }
1429         ).map_err(|e| SendError::Secp256k1(e))?;
1430
1431         if let Some(control_tlvs) = final_control_tlvs {
1432                 payloads.push((Payload::Receive {
1433                         control_tlvs,
1434                         reply_path: reply_path.take(),
1435                         message,
1436                 }, prev_control_tlvs_ss.unwrap()));
1437         } else {
1438                 payloads.push((Payload::Receive {
1439                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1440                         reply_path: reply_path.take(),
1441                         message,
1442                 }, prev_control_tlvs_ss.unwrap()));
1443         }
1444
1445         Ok((payloads, onion_packet_keys))
1446 }
1447
1448 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1449 fn construct_onion_message_packet<T: OnionMessageContents>(payloads: Vec<(Payload<T>, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
1450         // Spec rationale:
1451         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1452         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1453         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1454         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1455         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1456                 SMALL_PACKET_HOP_DATA_LEN
1457         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1458                 BIG_PACKET_HOP_DATA_LEN
1459         } else { return Err(()) };
1460
1461         onion_utils::construct_onion_message_packet::<_, _>(
1462                 payloads, onion_keys, prng_seed, hop_data_len)
1463 }