_ 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_announcement = network_graph
 387                                 .node(&NodeId::from_pubkey(&first_node))
 388                                 .and_then(|node_info| node_info.announcement_info.as_ref())
 389                                 .and_then(|announcement_info| announcement_info.announcement_message.as_ref())
 390                                 .map(|node_announcement| &node_announcement.contents);
 391
 392                         match node_announcement {
 393                                 Some(node_announcement) if node_announcement.features.supports_onion_messages() => {
 394                                         let first_node_addresses = Some(node_announcement.addresses.clone());
 395                                         Ok(OnionMessagePath {
 396                                                 intermediate_nodes: vec![], destination, first_node_addresses
 397                                         })
 398                                 },
 399                                 _ => Err(()),
 400                         }
 401                 }
 402         }
 403
 404         fn create_blinded_paths<
 405                 T: secp256k1::Signing + secp256k1::Verification
 406         >(
 407                 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 408         ) -> Result<Vec<BlindedPath>, ()> {
 409                 // Limit the number of blinded paths that are computed.
 410                 const MAX_PATHS: usize = 3;
 411
 412                 // Ensure peers have at least three channels so that it is more difficult to infer the
 413                 // recipient's node_id.
 414                 const MIN_PEER_CHANNELS: usize = 3;
 415
 416                 let network_graph = self.network_graph.deref().read_only();
 417                 let is_recipient_announced =
 418                         network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient));
 419
 420                 let mut peer_info = peers.iter()
 421                         // Limit to peers with announced channels
 422                         .filter_map(|pubkey|
 423                                 network_graph
 424                                         .node(&NodeId::from_pubkey(pubkey))
 425                                         .filter(|info| info.channels.len() >= MIN_PEER_CHANNELS)
 426                                         .map(|info| (*pubkey, info.is_tor_only(), info.channels.len()))
 427                         )
 428                         // Exclude Tor-only nodes when the recipient is announced.
 429                         .filter(|(_, is_tor_only, _)| !(*is_tor_only && is_recipient_announced))
 430                         .collect::<Vec<_>>();
 431
 432                 // Prefer using non-Tor nodes with the most channels as the introduction node.
 433                 peer_info.sort_unstable_by(|(_, a_tor_only, a_channels), (_, b_tor_only, b_channels)| {
 434                         a_tor_only.cmp(b_tor_only).then(a_channels.cmp(b_channels).reverse())
 435                 });
 436
 437                 let paths = peer_info.into_iter()
 438                         .map(|(pubkey, _, _)| vec![pubkey, recipient])
 439                         .map(|node_pks| BlindedPath::new_for_message(&node_pks, &*self.entropy_source, secp_ctx))
 440                         .take(MAX_PATHS)
 441                         .collect::<Result<Vec<_>, _>>();
 442
 443                 match paths {
 444                         Ok(paths) if !paths.is_empty() => Ok(paths),
 445                         _ => {
 446                                 if is_recipient_announced {
 447                                         BlindedPath::one_hop_for_message(recipient, &*self.entropy_source, secp_ctx)
 448                                                 .map(|path| vec![path])
 449                                 } else {
 450                                         Err(())
 451                                 }
 452                         },
 453                 }
 454         }
 455 }
 456
 457 /// A path for sending an [`OnionMessage`].
 458 #[derive(Clone)]
 459 pub struct OnionMessagePath {
 460         /// Nodes on the path between the sender and the destination.
 461         pub intermediate_nodes: Vec<PublicKey>,
 462
 463         /// The recipient of the message.
 464         pub destination: Destination,
 465
 466         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 467         ///
 468         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 469         /// this to initiate such a connection.
 470         pub first_node_addresses: Option<Vec<SocketAddress>>,
 471 }
 472
 473 impl OnionMessagePath {
 474         /// Returns the first node in the path.
 475         pub fn first_node(&self) -> Option<PublicKey> {
 476                 self.intermediate_nodes
 477                         .first()
 478                         .copied()
 479                         .or_else(|| self.destination.first_node())
 480         }
 481 }
 482
 483 /// The destination of an onion message.
 484 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 485 pub enum Destination {
 486         /// We're sending this onion message to a node.
 487         Node(PublicKey),
 488         /// We're sending this onion message to a blinded path.
 489         BlindedPath(BlindedPath),
 490 }
 491
 492 impl Destination {
 493         /// Attempts to resolve the [`IntroductionNode::DirectedShortChannelId`] of a
 494         /// [`Destination::BlindedPath`] to a [`IntroductionNode::NodeId`], if applicable, using the
 495         /// provided [`ReadOnlyNetworkGraph`].
 496         pub fn resolve(&mut self, network_graph: &ReadOnlyNetworkGraph) {
 497                 if let Destination::BlindedPath(path) = self {
 498                         if let IntroductionNode::DirectedShortChannelId(..) = path.introduction_node {
 499                                 if let Some(pubkey) = path
 500                                         .public_introduction_node_id(network_graph)
 501                                         .and_then(|node_id| node_id.as_pubkey().ok())
 502                                 {
 503                                         path.introduction_node = IntroductionNode::NodeId(pubkey);
 504                                 }
 505                         }
 506                 }
 507         }
 508
 509         pub(super) fn num_hops(&self) -> usize {
 510                 match self {
 511                         Destination::Node(_) => 1,
 512                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 513                 }
 514         }
 515
 516         fn first_node(&self) -> Option<PublicKey> {
 517                 match self {
 518                         Destination::Node(node_id) => Some(*node_id),
 519                         Destination::BlindedPath(BlindedPath { introduction_node, .. }) => {
 520                                 match introduction_node {
 521                                         IntroductionNode::NodeId(pubkey) => Some(*pubkey),
 522                                         IntroductionNode::DirectedShortChannelId(..) => None,
 523                                 }
 524                         },
 525                 }
 526         }
 527 }
 528
 529 /// Result of successfully [sending an onion message].
 530 ///
 531 /// [sending an onion message]: OnionMessenger::send_onion_message
 532 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 533 pub enum SendSuccess {
 534         /// The message was buffered and will be sent once it is processed by
 535         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 536         Buffered,
 537         /// The message was buffered and will be sent once the node is connected as a peer and it is
 538         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 539         BufferedAwaitingConnection(PublicKey),
 540 }
 541
 542 /// Errors that may occur when [sending an onion message].
 543 ///
 544 /// [sending an onion message]: OnionMessenger::send_onion_message
 545 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 546 pub enum SendError {
 547         /// Errored computing onion message packet keys.
 548         Secp256k1(secp256k1::Error),
 549         /// Because implementations such as Eclair will drop onion messages where the message packet
 550         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 551         TooBigPacket,
 552         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 553         /// hops.
 554         TooFewBlindedHops,
 555         /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
 556         InvalidFirstHop(PublicKey),
 557         /// A path from the sender to the destination could not be found by the [`MessageRouter`].
 558         PathNotFound,
 559         /// Onion message contents must have a TLV type >= 64.
 560         InvalidMessage,
 561         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 562         BufferFull,
 563         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 564         ///
 565         /// [`NodeSigner`]: crate::sign::NodeSigner
 566         GetNodeIdFailed,
 567         /// The provided [`Destination`] has a blinded path with an unresolved introduction node. An
 568         /// attempt to resolve it in the [`MessageRouter`] when finding an [`OnionMessagePath`] likely
 569         /// failed.
 570         UnresolvedIntroductionNode,
 571         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 572         /// advance the blinded path to make the second hop the new introduction node. Either
 573         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 574         /// new blinding point, or we were attempting to send to ourselves.
 575         BlindedPathAdvanceFailed,
 576 }
 577
 578 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 579 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 580 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 581 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 582 /// message types.
 583 ///
 584 /// See [`OnionMessenger`] for example usage.
 585 ///
 586 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 587 /// [`CustomMessage`]: Self::CustomMessage
 588 pub trait CustomOnionMessageHandler {
 589         /// The message known to the handler. To support multiple message types, you may want to make this
 590         /// an enum with a variant for each supported message.
 591         type CustomMessage: OnionMessageContents;
 592
 593         /// Called with the custom message that was received, returning a response to send, if any.
 594         ///
 595         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 596         fn handle_custom_message(&self, message: Self::CustomMessage, responder: Option<Responder>) -> ResponseInstruction<Self::CustomMessage>;
 597
 598         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 599         /// message type is unknown.
 600         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 601
 602         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 603         ///
 604         /// Typically, this is used for messages initiating a message flow rather than in response to
 605         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 606         #[cfg(not(c_bindings))]
 607         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 608
 609         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 610         ///
 611         /// Typically, this is used for messages initiating a message flow rather than in response to
 612         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 613         #[cfg(c_bindings)]
 614         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 615 }
 616
 617 /// A processed incoming onion message, containing either a Forward (another onion message)
 618 /// or a Receive payload with decrypted contents.
 619 #[derive(Clone, Debug)]
 620 pub enum PeeledOnion<T: OnionMessageContents> {
 621         /// Forwarded onion, with the next node id and a new onion
 622         Forward(NextMessageHop, OnionMessage),
 623         /// Received onion message, with decrypted contents, path_id, and reply path
 624         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 625 }
 626
 627
 628 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 629 /// `path`, first calling [`Destination::resolve`] on `path.destination` with the given
 630 /// [`ReadOnlyNetworkGraph`].
 631 ///
 632 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 633 /// needed to connect to the first node.
 634 pub fn create_onion_message_resolving_destination<
 635         ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents
 636 >(
 637         entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
 638         network_graph: &ReadOnlyNetworkGraph, secp_ctx: &Secp256k1<secp256k1::All>,
 639         mut path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 640 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 641 where
 642         ES::Target: EntropySource,
 643         NS::Target: NodeSigner,
 644         NL::Target: NodeIdLookUp,
 645 {
 646         path.destination.resolve(network_graph);
 647         create_onion_message(
 648                 entropy_source, node_signer, node_id_lookup, secp_ctx, path, contents, reply_path,
 649         )
 650 }
 651
 652 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 653 /// `path`.
 654 ///
 655 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 656 /// needed to connect to the first node.
 657 ///
 658 /// Returns [`SendError::UnresolvedIntroductionNode`] if:
 659 /// - `destination` contains a blinded path with an [`IntroductionNode::DirectedShortChannelId`],
 660 /// - unless it can be resolved by [`NodeIdLookUp::next_node_id`].
 661 /// Use [`create_onion_message_resolving_destination`] instead to resolve the introduction node
 662 /// first with a [`ReadOnlyNetworkGraph`].
 663 pub fn create_onion_message<ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents>(
 664         entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
 665         secp_ctx: &Secp256k1<secp256k1::All>, path: OnionMessagePath, contents: T,
 666         reply_path: Option<BlindedPath>,
 667 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 668 where
 669         ES::Target: EntropySource,
 670         NS::Target: NodeSigner,
 671         NL::Target: NodeIdLookUp,
 672 {
 673         let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
 674         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 675                 if blinded_hops.is_empty() {
 676                         return Err(SendError::TooFewBlindedHops);
 677                 }
 678         }
 679
 680         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 681
 682         // If we are sending straight to a blinded path and we are the introduction node, we need to
 683         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 684         if intermediate_nodes.len() == 0 {
 685                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 686                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 687                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 688                         let introduction_node_id = match blinded_path.introduction_node {
 689                                 IntroductionNode::NodeId(pubkey) => pubkey,
 690                                 IntroductionNode::DirectedShortChannelId(direction, scid) => {
 691                                         match node_id_lookup.next_node_id(scid) {
 692                                                 Some(next_node_id) => *direction.select_pubkey(&our_node_id, &next_node_id),
 693                                                 None => return Err(SendError::UnresolvedIntroductionNode),
 694                                         }
 695                                 },
 696                         };
 697                         if introduction_node_id == our_node_id {
 698                                 advance_path_by_one(blinded_path, node_signer, node_id_lookup, &secp_ctx)
 699                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 700                         }
 701                 }
 702         }
 703
 704         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 705         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 706         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 707                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 708         } else {
 709                 match &destination {
 710                         Destination::Node(pk) => (*pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 711                         Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, .. }) => {
 712                                 match introduction_node {
 713                                         IntroductionNode::NodeId(pubkey) => (*pubkey, *blinding_point),
 714                                         IntroductionNode::DirectedShortChannelId(..) => {
 715                                                 return Err(SendError::UnresolvedIntroductionNode);
 716                                         },
 717                                 }
 718                         }
 719                 }
 720         };
 721         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 722                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret
 723         )?;
 724
 725         let prng_seed = entropy_source.get_secure_random_bytes();
 726         let onion_routing_packet = construct_onion_message_packet(
 727                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 728
 729         let message = OnionMessage { blinding_point, onion_routing_packet };
 730         Ok((first_node_id, message, first_node_addresses))
 731 }
 732
 733 /// Decode one layer of an incoming [`OnionMessage`].
 734 ///
 735 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 736 /// receiver.
 737 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 738         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 739         custom_handler: CMH,
 740 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 741 where
 742         NS::Target: NodeSigner,
 743         L::Target: Logger,
 744         CMH::Target: CustomOnionMessageHandler,
 745 {
 746         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 747                 Ok(ss) => ss,
 748                 Err(e) =>  {
 749                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 750                         return Err(());
 751                 }
 752         };
 753         let onion_decode_ss = {
 754                 let blinding_factor = {
 755                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 756                         hmac.input(control_tlvs_ss.as_ref());
 757                         Hmac::from_engine(hmac).to_byte_array()
 758                 };
 759                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 760                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 761                 {
 762                         Ok(ss) => ss.secret_bytes(),
 763                         Err(()) => {
 764                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 765                                 return Err(());
 766                         }
 767                 }
 768         };
 769         match onion_utils::decode_next_untagged_hop(
 770                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 771                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 772         ) {
 773                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 774                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 775                 }, None)) => {
 776                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 777                 },
 778                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 779                         next_hop, next_blinding_override
 780                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 781                         // TODO: we need to check whether `next_hop` is our node, in which case this is a dummy
 782                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 783                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 784                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 785                         // for now.
 786                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 787                                 Ok(pk) => pk,
 788                                 Err(e) => {
 789                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 790                                         return Err(())
 791                                 }
 792                         };
 793                         let outgoing_packet = Packet {
 794                                 version: 0,
 795                                 public_key: new_pubkey,
 796                                 hop_data: new_packet_bytes,
 797                                 hmac: next_hop_hmac,
 798                         };
 799                         let onion_message = OnionMessage {
 800                                 blinding_point: match next_blinding_override {
 801                                         Some(blinding_point) => blinding_point,
 802                                         None => {
 803                                                 match onion_utils::next_hop_pubkey(
 804                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 805                                                 ) {
 806                                                         Ok(bp) => bp,
 807                                                         Err(e) => {
 808                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 809                                                                 return Err(())
 810                                                         }
 811                                                 }
 812                                         }
 813                                 },
 814                                 onion_routing_packet: outgoing_packet,
 815                         };
 816
 817                         Ok(PeeledOnion::Forward(next_hop, onion_message))
 818                 },
 819                 Err(e) => {
 820                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 821                         Err(())
 822                 },
 823                 _ => {
 824                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 825                         Err(())
 826                 },
 827         }
 828 }
 829
 830 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 831 OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
 832 where
 833         ES::Target: EntropySource,
 834         NS::Target: NodeSigner,
 835         L::Target: Logger,
 836         NL::Target: NodeIdLookUp,
 837         MR::Target: MessageRouter,
 838         OMH::Target: OffersMessageHandler,
 839         CMH::Target: CustomOnionMessageHandler,
 840 {
 841         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 842         /// their respective handlers.
 843         pub fn new(
 844                 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL, message_router: MR,
 845                 offers_handler: OMH, custom_handler: CMH
 846         ) -> Self {
 847                 Self::new_inner(
 848                         entropy_source, node_signer, logger, node_id_lookup, message_router,
 849                         offers_handler, custom_handler, false
 850                 )
 851         }
 852
 853         /// Similar to [`Self::new`], but rather than dropping onion messages that are
 854         /// intended to be forwarded to offline peers, we will intercept them for
 855         /// later forwarding.
 856         ///
 857         /// Interception flow:
 858         /// 1. If an onion message for an offline peer is received, `OnionMessenger` will
 859         ///    generate an [`Event::OnionMessageIntercepted`]. Event handlers can
 860         ///    then choose to persist this onion message for later forwarding, or drop
 861         ///    it.
 862         /// 2. When the offline peer later comes back online, `OnionMessenger` will
 863         ///    generate an [`Event::OnionMessagePeerConnected`]. Event handlers will
 864         ///    then fetch all previously intercepted onion messages for this peer.
 865         /// 3. Once the stored onion messages are fetched, they can finally be
 866         ///    forwarded to the now-online peer via [`Self::forward_onion_message`].
 867         ///
 868         /// # Note
 869         ///
 870         /// LDK will not rate limit how many [`Event::OnionMessageIntercepted`]s
 871         /// are generated, so it is the caller's responsibility to limit how many
 872         /// onion messages are persisted and only persist onion messages for relevant
 873         /// peers.
 874         pub fn new_with_offline_peer_interception(
 875                 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL,
 876                 message_router: MR, offers_handler: OMH, custom_handler: CMH
 877         ) -> Self {
 878                 Self::new_inner(
 879                         entropy_source, node_signer, logger, node_id_lookup, message_router,
 880                         offers_handler, custom_handler, true
 881                 )
 882         }
 883
 884         fn new_inner(
 885                 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL,
 886                 message_router: MR, offers_handler: OMH, custom_handler: CMH,
 887                 intercept_messages_for_offline_peers: bool
 888         ) -> Self {
 889                 let mut secp_ctx = Secp256k1::new();
 890                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 891                 OnionMessenger {
 892                         entropy_source,
 893                         node_signer,
 894                         message_recipients: Mutex::new(new_hash_map()),
 895                         secp_ctx,
 896                         logger,
 897                         node_id_lookup,
 898                         message_router,
 899                         offers_handler,
 900                         custom_handler,
 901                         intercept_messages_for_offline_peers,
 902                         pending_events: Mutex::new(Vec::new()),
 903                 }
 904         }
 905
 906         #[cfg(test)]
 907         pub(crate) fn set_offers_handler(&mut self, offers_handler: OMH) {
 908                 self.offers_handler = offers_handler;
 909         }
 910
 911         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
 912         ///
 913         /// See [`OnionMessenger`] for example usage.
 914         pub fn send_onion_message<T: OnionMessageContents>(
 915                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
 916         ) -> Result<SendSuccess, SendError> {
 917                 self.find_path_and_enqueue_onion_message(
 918                         contents, destination, reply_path, format_args!("")
 919                 )
 920         }
 921
 922         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 923                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 924                 log_suffix: fmt::Arguments
 925         ) -> Result<SendSuccess, SendError> {
 926                 let mut logger = WithContext::from(&self.logger, None, None, None);
 927                 let result = self.find_path(destination).and_then(|path| {
 928                         let first_hop = path.intermediate_nodes.get(0).map(|p| *p);
 929                         logger = WithContext::from(&self.logger, first_hop, None, None);
 930                         self.enqueue_onion_message(path, contents, reply_path, log_suffix)
 931                 });
 932
 933                 match result.as_ref() {
 934                         Err(SendError::GetNodeIdFailed) => {
 935                                 log_warn!(logger, "Unable to retrieve node id {}", log_suffix);
 936                         },
 937                         Err(SendError::PathNotFound) => {
 938                                 log_trace!(logger, "Failed to find path {}", log_suffix);
 939                         },
 940                         Err(e) => {
 941                                 log_trace!(logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 942                         },
 943                         Ok(SendSuccess::Buffered) => {
 944                                 log_trace!(logger, "Buffered onion message {}", log_suffix);
 945                         },
 946                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
 947                                 log_trace!(
 948                                         logger,
 949                                         "Buffered onion message waiting on peer connection {}: {}",
 950                                         log_suffix, node_id
 951                                 );
 952                         },
 953                 }
 954
 955                 result
 956         }
 957
 958         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
 959                 let sender = self.node_signer
 960                         .get_node_id(Recipient::Node)
 961                         .map_err(|_| SendError::GetNodeIdFailed)?;
 962
 963                 let peers = self.message_recipients.lock().unwrap()
 964                         .iter()
 965                         .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
 966                         .map(|(node_id, _)| *node_id)
 967                         .collect();
 968
 969                 self.message_router
 970                         .find_path(sender, peers, destination)
 971                         .map_err(|_| SendError::PathNotFound)
 972         }
 973
 974         fn enqueue_onion_message<T: OnionMessageContents>(
 975                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 976                 log_suffix: fmt::Arguments
 977         ) -> Result<SendSuccess, SendError> {
 978                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 979
 980                 let (first_node_id, onion_message, addresses) = create_onion_message(
 981                         &self.entropy_source, &self.node_signer, &self.node_id_lookup, &self.secp_ctx, path,
 982                         contents, reply_path,
 983                 )?;
 984
 985                 let mut message_recipients = self.message_recipients.lock().unwrap();
 986                 if outbound_buffer_full(&first_node_id, &message_recipients) {
 987                         return Err(SendError::BufferFull);
 988                 }
 989
 990                 match message_recipients.entry(first_node_id) {
 991                         hash_map::Entry::Vacant(e) => match addresses {
 992                                 None => Err(SendError::InvalidFirstHop(first_node_id)),
 993                                 Some(addresses) => {
 994                                         e.insert(OnionMessageRecipient::pending_connection(addresses))
 995                                                 .enqueue_message(onion_message);
 996                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 997                                 },
 998                         },
 999                         hash_map::Entry::Occupied(mut e) => {
1000                                 e.get_mut().enqueue_message(onion_message);
1001                                 if e.get().is_connected() {
1002                                         Ok(SendSuccess::Buffered)
1003                                 } else {
1004                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
1005                                 }
1006                         },
1007                 }
1008         }
1009
1010         /// Forwards an [`OnionMessage`] to `peer_node_id`. Useful if we initialized
1011         /// the [`OnionMessenger`] with [`Self::new_with_offline_peer_interception`]
1012         /// and want to forward a previously intercepted onion message to a peer that
1013         /// has just come online.
1014         pub fn forward_onion_message(
1015                 &self, message: OnionMessage, peer_node_id: &PublicKey
1016         ) -> Result<(), SendError> {
1017                 let mut message_recipients = self.message_recipients.lock().unwrap();
1018                 if outbound_buffer_full(&peer_node_id, &message_recipients) {
1019                         return Err(SendError::BufferFull);
1020                 }
1021
1022                 match message_recipients.entry(*peer_node_id) {
1023                         hash_map::Entry::Occupied(mut e) if e.get().is_connected() => {
1024                                 e.get_mut().enqueue_message(message);
1025                                 Ok(())
1026                         },
1027                         _ => Err(SendError::InvalidFirstHop(*peer_node_id))
1028                 }
1029         }
1030
1031         #[cfg(any(test, feature = "_test_utils"))]
1032         pub fn send_onion_message_using_path<T: OnionMessageContents>(
1033                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
1034         ) -> Result<SendSuccess, SendError> {
1035                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
1036         }
1037
1038         pub(crate) fn peel_onion_message(
1039                 &self, msg: &OnionMessage
1040         ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()> {
1041                 peel_onion_message(
1042                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
1043                 )
1044         }
1045
1046         fn handle_onion_message_response<T: OnionMessageContents>(
1047                 &self, response: ResponseInstruction<T>
1048         ) {
1049                 if let ResponseInstruction::WithoutReplyPath(response) = response {
1050                         let message_type = response.message.msg_type();
1051                         let _ = self.find_path_and_enqueue_onion_message(
1052                                 response.message, Destination::BlindedPath(response.reply_path), None,
1053                                 format_args!(
1054                                         "when responding with {} to an onion message with path_id {:02x?}",
1055                                         message_type,
1056                                         response.path_id
1057                                 )
1058                         );
1059                 }
1060         }
1061
1062         #[cfg(test)]
1063         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
1064                 let mut message_recipients = self.message_recipients.lock().unwrap();
1065                 let mut msgs = new_hash_map();
1066                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
1067                 // release the pending message buffers individually.
1068                 for (node_id, recipient) in &mut *message_recipients {
1069                         msgs.insert(*node_id, recipient.release_pending_messages());
1070                 }
1071                 msgs
1072         }
1073
1074         fn enqueue_event(&self, event: Event) {
1075                 const MAX_EVENTS_BUFFER_SIZE: usize = (1 << 10) * 256;
1076                 let mut pending_events = self.pending_events.lock().unwrap();
1077                 let total_buffered_bytes: usize = pending_events
1078                         .iter()
1079                         .map(|ev| ev.serialized_length())
1080                         .sum();
1081                 if total_buffered_bytes >= MAX_EVENTS_BUFFER_SIZE {
1082                         log_trace!(self.logger, "Dropping event {:?}: buffer full", event);
1083                         return
1084                 }
1085                 pending_events.push(event);
1086         }
1087 }
1088
1089 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
1090         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
1091         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
1092         let mut total_buffered_bytes = 0;
1093         let mut peer_buffered_bytes = 0;
1094         for (pk, peer_buf) in buffer {
1095                 for om in peer_buf.pending_messages() {
1096                         let om_len = om.serialized_length();
1097                         if pk == peer_node_id {
1098                                 peer_buffered_bytes += om_len;
1099                         }
1100                         total_buffered_bytes += om_len;
1101
1102                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
1103                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
1104                         {
1105                                 return true
1106                         }
1107                 }
1108         }
1109         false
1110 }
1111
1112 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
1113 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
1114 where
1115         ES::Target: EntropySource,
1116         NS::Target: NodeSigner,
1117         L::Target: Logger,
1118         NL::Target: NodeIdLookUp,
1119         MR::Target: MessageRouter,
1120         OMH::Target: OffersMessageHandler,
1121         CMH::Target: CustomOnionMessageHandler,
1122 {
1123         fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
1124                 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
1125                         if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
1126                                 if let Some(addresses) = addresses.take() {
1127                                         handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
1128                                 }
1129                         }
1130                 }
1131                 let mut events = Vec::new();
1132                 core::mem::swap(&mut *self.pending_events.lock().unwrap(), &mut events);
1133                 for ev in events {
1134                         handler.handle_event(ev);
1135                 }
1136         }
1137 }
1138
1139 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
1140 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
1141 where
1142         ES::Target: EntropySource,
1143         NS::Target: NodeSigner,
1144         L::Target: Logger,
1145         NL::Target: NodeIdLookUp,
1146         MR::Target: MessageRouter,
1147         OMH::Target: OffersMessageHandler,
1148         CMH::Target: CustomOnionMessageHandler,
1149 {
1150         fn handle_onion_message(&self, peer_node_id: &PublicKey, msg: &OnionMessage) {
1151                 let logger = WithContext::from(&self.logger, Some(*peer_node_id), None, None);
1152                 match self.peel_onion_message(msg) {
1153                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
1154                                 log_trace!(
1155                                         logger,
1156                                         "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
1157                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
1158
1159                                 match message {
1160                                         ParsedOnionMessageContents::Offers(msg) => {
1161                                                 let responder = reply_path.map(
1162                                                         |reply_path| Responder::new(reply_path, path_id)
1163                                                 );
1164                                                 let response_instructions = self.offers_handler.handle_message(msg, responder);
1165                                                 self.handle_onion_message_response(response_instructions);
1166                                         },
1167                                         ParsedOnionMessageContents::Custom(msg) => {
1168                                                 let responder = reply_path.map(
1169                                                         |reply_path| Responder::new(reply_path, path_id)
1170                                                 );
1171                                                 let response_instructions = self.custom_handler.handle_custom_message(msg, responder);
1172                                                 self.handle_onion_message_response(response_instructions);
1173                                         },
1174                                 }
1175                         },
1176                         Ok(PeeledOnion::Forward(next_hop, onion_message)) => {
1177                                 let next_node_id = match next_hop {
1178                                         NextMessageHop::NodeId(pubkey) => pubkey,
1179                                         NextMessageHop::ShortChannelId(scid) => match self.node_id_lookup.next_node_id(scid) {
1180                                                 Some(pubkey) => pubkey,
1181                                                 None => {
1182                                                         log_trace!(self.logger, "Dropping forwarded onion messager: unable to resolve next hop using SCID {}", scid);
1183                                                         return
1184                                                 },
1185                                         },
1186                                 };
1187
1188                                 let mut message_recipients = self.message_recipients.lock().unwrap();
1189                                 if outbound_buffer_full(&next_node_id, &message_recipients) {
1190                                         log_trace!(
1191                                                 logger,
1192                                                 "Dropping forwarded onion message to peer {}: outbound buffer full",
1193                                                 next_node_id);
1194                                         return
1195                                 }
1196
1197                                 #[cfg(fuzzing)]
1198                                 message_recipients
1199                                         .entry(next_node_id)
1200                                         .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
1201
1202                                 match message_recipients.entry(next_node_id) {
1203                                         hash_map::Entry::Occupied(mut e) if matches!(
1204                                                 e.get(), OnionMessageRecipient::ConnectedPeer(..)
1205                                         ) => {
1206                                                 e.get_mut().enqueue_message(onion_message);
1207                                                 log_trace!(logger, "Forwarding an onion message to peer {}", next_node_id);
1208                                         },
1209                                         _ if self.intercept_messages_for_offline_peers => {
1210                                                 self.enqueue_event(
1211                                                         Event::OnionMessageIntercepted {
1212                                                                 peer_node_id: next_node_id, message: onion_message
1213                                                         }
1214                                                 );
1215                                         },
1216                                         _ => {
1217                                                 log_trace!(
1218                                                         logger,
1219                                                         "Dropping forwarded onion message to disconnected peer {}",
1220                                                         next_node_id);
1221                                                 return
1222                                         },
1223                                 }
1224                         },
1225                         Err(e) => {
1226                                 log_error!(logger, "Failed to process onion message {:?}", e);
1227                         }
1228                 }
1229         }
1230
1231         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
1232                 if init.features.supports_onion_messages() {
1233                         self.message_recipients.lock().unwrap()
1234                                 .entry(*their_node_id)
1235                                 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
1236                                 .mark_connected();
1237                         if self.intercept_messages_for_offline_peers {
1238                                 self.enqueue_event(
1239                                         Event::OnionMessagePeerConnected { peer_node_id: *their_node_id }
1240                                 );
1241                         }
1242                 } else {
1243                         self.message_recipients.lock().unwrap().remove(their_node_id);
1244                 }
1245
1246                 Ok(())
1247         }
1248
1249         fn peer_disconnected(&self, their_node_id: &PublicKey) {
1250                 match self.message_recipients.lock().unwrap().remove(their_node_id) {
1251                         Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
1252                         Some(_) => debug_assert!(false),
1253                         None => {},
1254                 }
1255         }
1256
1257         fn timer_tick_occurred(&self) {
1258                 let mut message_recipients = self.message_recipients.lock().unwrap();
1259
1260                 // Drop any pending recipients since the last call to avoid retaining buffered messages for
1261                 // too long.
1262                 message_recipients.retain(|_, recipient| match recipient {
1263                         OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
1264                         OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
1265                         _ => true,
1266                 });
1267
1268                 // Increment a timer tick for pending recipients so that their buffered messages are dropped
1269                 // at MAX_TIMER_TICKS.
1270                 for recipient in message_recipients.values_mut() {
1271                         if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
1272                                 *ticks += 1;
1273                         }
1274                 }
1275         }
1276
1277         fn provided_node_features(&self) -> NodeFeatures {
1278                 let mut features = NodeFeatures::empty();
1279                 features.set_onion_messages_optional();
1280                 features
1281         }
1282
1283         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1284                 let mut features = InitFeatures::empty();
1285                 features.set_onion_messages_optional();
1286                 features
1287         }
1288
1289         // Before returning any messages to send for the peer, this method will see if any messages were
1290         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1291         // node, and then enqueue the message for sending to the first peer in the full path.
1292         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1293                 // Enqueue any initiating `OffersMessage`s to send.
1294                 for message in self.offers_handler.release_pending_messages() {
1295                         #[cfg(not(c_bindings))]
1296                         let PendingOnionMessage { contents, destination, reply_path } = message;
1297                         #[cfg(c_bindings)]
1298                         let (contents, destination, reply_path) = message;
1299                         let _ = self.find_path_and_enqueue_onion_message(
1300                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
1301                         );
1302                 }
1303
1304                 // Enqueue any initiating `CustomMessage`s to send.
1305                 for message in self.custom_handler.release_pending_custom_messages() {
1306                         #[cfg(not(c_bindings))]
1307                         let PendingOnionMessage { contents, destination, reply_path } = message;
1308                         #[cfg(c_bindings)]
1309                         let (contents, destination, reply_path) = message;
1310                         let _ = self.find_path_and_enqueue_onion_message(
1311                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
1312                         );
1313                 }
1314
1315                 self.message_recipients.lock().unwrap()
1316                         .get_mut(&peer_node_id)
1317                         .and_then(|buffer| buffer.dequeue_message())
1318         }
1319 }
1320
1321 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1322 // produces
1323 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1324 /// [`SimpleArcPeerManager`]. See their docs for more details.
1325 ///
1326 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1327 ///
1328 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1329 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1330 #[cfg(not(c_bindings))]
1331 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1332         Arc<KeysManager>,
1333         Arc<KeysManager>,
1334         Arc<L>,
1335         Arc<SimpleArcChannelManager<M, T, F, L>>,
1336         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>, Arc<KeysManager>>>,
1337         Arc<SimpleArcChannelManager<M, T, F, L>>,
1338         IgnoringMessageHandler
1339 >;
1340
1341 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1342 /// [`SimpleRefPeerManager`]. See their docs for more details.
1343 ///
1344 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1345 ///
1346 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1347 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1348 #[cfg(not(c_bindings))]
1349 pub type SimpleRefOnionMessenger<
1350         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1351 > = OnionMessenger<
1352         &'a KeysManager,
1353         &'a KeysManager,
1354         &'b L,
1355         &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1356         &'j DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L, &'a KeysManager>,
1357         &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1358         IgnoringMessageHandler
1359 >;
1360
1361 /// Construct onion packet payloads and keys for sending an onion message along the given
1362 /// `unblinded_path` to the given `destination`.
1363 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1364         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1365         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1366 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), SendError> {
1367         let num_hops = unblinded_path.len() + destination.num_hops();
1368         let mut payloads = Vec::with_capacity(num_hops);
1369         let mut onion_packet_keys = Vec::with_capacity(num_hops);
1370
1371         let (mut intro_node_id_blinding_pt, num_blinded_hops) = match &destination {
1372                 Destination::Node(_) => (None, 0),
1373                 Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, blinded_hops }) => {
1374                         let introduction_node_id = match introduction_node {
1375                                 IntroductionNode::NodeId(pubkey) => pubkey,
1376                                 IntroductionNode::DirectedShortChannelId(..) => {
1377                                         return Err(SendError::UnresolvedIntroductionNode);
1378                                 },
1379                         };
1380                         (Some((*introduction_node_id, *blinding_point)), blinded_hops.len())
1381                 },
1382         };
1383         let num_unblinded_hops = num_hops - num_blinded_hops;
1384
1385         let mut unblinded_path_idx = 0;
1386         let mut blinded_path_idx = 0;
1387         let mut prev_control_tlvs_ss = None;
1388         let mut final_control_tlvs = None;
1389         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1390                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1391                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1392                                 if let Some(ss) = prev_control_tlvs_ss.take() {
1393                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1394                                                 ForwardTlvs {
1395                                                         next_hop: NextMessageHop::NodeId(unblinded_pk_opt.unwrap()),
1396                                                         next_blinding_override: None,
1397                                                 }
1398                                         )), ss));
1399                                 }
1400                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1401                                 unblinded_path_idx += 1;
1402                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1403                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1404                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1405                                                 next_hop: NextMessageHop::NodeId(intro_node_id),
1406                                                 next_blinding_override: Some(blinding_pt),
1407                                         })), control_tlvs_ss));
1408                                 }
1409                         }
1410                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1411                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1412                                         control_tlvs_ss));
1413                                 blinded_path_idx += 1;
1414                         } else if let Some(encrypted_payload) = enc_payload_opt {
1415                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1416                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1417                         }
1418
1419                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1420                         onion_packet_keys.push(onion_utils::OnionKeys {
1421                                 #[cfg(test)]
1422                                 shared_secret: onion_packet_ss,
1423                                 #[cfg(test)]
1424                                 blinding_factor: [0; 32],
1425                                 ephemeral_pubkey,
1426                                 rho,
1427                                 mu,
1428                         });
1429                 }
1430         ).map_err(|e| SendError::Secp256k1(e))?;
1431
1432         if let Some(control_tlvs) = final_control_tlvs {
1433                 payloads.push((Payload::Receive {
1434                         control_tlvs,
1435                         reply_path: reply_path.take(),
1436                         message,
1437                 }, prev_control_tlvs_ss.unwrap()));
1438         } else {
1439                 payloads.push((Payload::Receive {
1440                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1441                         reply_path: reply_path.take(),
1442                         message,
1443                 }, prev_control_tlvs_ss.unwrap()));
1444         }
1445
1446         Ok((payloads, onion_packet_keys))
1447 }
1448
1449 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1450 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, ()> {
1451         // Spec rationale:
1452         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1453         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1454         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1455         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1456         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1457                 SMALL_PACKET_HOP_DATA_LEN
1458         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1459                 BIG_PACKET_HOP_DATA_LEN
1460         } else { return Err(()) };
1461
1462         onion_utils::construct_onion_message_packet::<_, _>(
1463                 payloads, onion_keys, prng_seed, hop_data_len)
1464 }