_ 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, ForwardNode, 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::blinded_path::message::ForwardNode;
  75 /// # use lightning::sign::{EntropySource, KeysManager};
  76 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  77 /// # use lightning::onion_message::messenger::{Destination, MessageRouter, OnionMessagePath, OnionMessenger};
  78 /// # use lightning::onion_message::packet::OnionMessageContents;
  79 /// # use lightning::util::logger::{Logger, Record};
  80 /// # use lightning::util::ser::{Writeable, Writer};
  81 /// # use lightning::io;
  82 /// # use std::sync::Arc;
  83 /// # struct FakeLogger;
  84 /// # impl Logger for FakeLogger {
  85 /// #     fn log(&self, record: Record) { println!("{:?}" , record); }
  86 /// # }
  87 /// # struct FakeMessageRouter {}
  88 /// # impl MessageRouter for FakeMessageRouter {
  89 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  90 /// #         let secp_ctx = Secp256k1::new();
  91 /// #         let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  92 /// #         let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  93 /// #         let hop_node_id2 = hop_node_id1;
  94 /// #         Ok(OnionMessagePath {
  95 /// #             intermediate_nodes: vec![hop_node_id1, hop_node_id2],
  96 /// #             destination,
  97 /// #             first_node_addresses: None,
  98 /// #         })
  99 /// #     }
 100 /// #     fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
 101 /// #         &self, _recipient: PublicKey, _peers: Vec<ForwardNode>, _secp_ctx: &Secp256k1<T>
 102 /// #     ) -> Result<Vec<BlindedPath>, ()> {
 103 /// #         unreachable!()
 104 /// #     }
 105 /// # }
 106 /// # let seed = [42u8; 32];
 107 /// # let time = Duration::from_secs(123456);
 108 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
 109 /// # let logger = Arc::new(FakeLogger {});
 110 /// # let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
 111 /// # let secp_ctx = Secp256k1::new();
 112 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
 113 /// # let (hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1);
 114 /// # let destination_node_id = hop_node_id1;
 115 /// # let node_id_lookup = EmptyNodeIdLookUp {};
 116 /// # let message_router = Arc::new(FakeMessageRouter {});
 117 /// # let custom_message_handler = IgnoringMessageHandler {};
 118 /// # let offers_message_handler = IgnoringMessageHandler {};
 119 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
 120 /// // ChannelManager.
 121 /// let onion_messenger = OnionMessenger::new(
 122 ///     &keys_manager, &keys_manager, logger, &node_id_lookup, message_router,
 123 ///     &offers_message_handler, &custom_message_handler
 124 /// );
 125
 126 /// # #[derive(Debug)]
 127 /// # struct YourCustomMessage {}
 128 /// impl Writeable for YourCustomMessage {
 129 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 130 ///             # Ok(())
 131 ///             // Write your custom onion message to `w`
 132 ///     }
 133 /// }
 134 /// impl OnionMessageContents for YourCustomMessage {
 135 ///     fn tlv_type(&self) -> u64 {
 136 ///             # let your_custom_message_type = 42;
 137 ///             your_custom_message_type
 138 ///     }
 139 ///     fn msg_type(&self) -> &'static str { "YourCustomMessageType" }
 140 /// }
 141 /// // Send a custom onion message to a node id.
 142 /// let destination = Destination::Node(destination_node_id);
 143 /// let reply_path = None;
 144 /// # let message = YourCustomMessage {};
 145 /// onion_messenger.send_onion_message(message, destination, reply_path);
 146 ///
 147 /// // Create a blinded path to yourself, for someone to send an onion message to.
 148 /// # let your_node_id = hop_node_id1;
 149 /// let hops = [
 150 ///     ForwardNode { node_id: hop_node_id3, short_channel_id: None },
 151 ///     ForwardNode { node_id: hop_node_id4, short_channel_id: None },
 152 /// ];
 153 /// let blinded_path = BlindedPath::new_for_message(&hops, your_node_id, &keys_manager, &secp_ctx).unwrap();
 154 ///
 155 /// // Send a custom onion message to a blinded path.
 156 /// let destination = Destination::BlindedPath(blinded_path);
 157 /// let reply_path = None;
 158 /// # let message = YourCustomMessage {};
 159 /// onion_messenger.send_onion_message(message, destination, reply_path);
 160 /// ```
 161 ///
 162 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 163 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 164 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 165 where
 166         ES::Target: EntropySource,
 167         NS::Target: NodeSigner,
 168         L::Target: Logger,
 169         NL::Target: NodeIdLookUp,
 170         MR::Target: MessageRouter,
 171         OMH::Target: OffersMessageHandler,
 172         CMH::Target: CustomOnionMessageHandler,
 173 {
 174         entropy_source: ES,
 175         node_signer: NS,
 176         logger: L,
 177         message_recipients: Mutex<HashMap<PublicKey, OnionMessageRecipient>>,
 178         secp_ctx: Secp256k1<secp256k1::All>,
 179         node_id_lookup: NL,
 180         message_router: MR,
 181         offers_handler: OMH,
 182         custom_handler: CMH,
 183         intercept_messages_for_offline_peers: bool,
 184         pending_events: Mutex<Vec<Event>>,
 185 }
 186
 187 /// [`OnionMessage`]s buffered to be sent.
 188 enum OnionMessageRecipient {
 189         /// Messages for a node connected as a peer.
 190         ConnectedPeer(VecDeque<OnionMessage>),
 191
 192         /// Messages for a node that is not yet connected, which are dropped after [`MAX_TIMER_TICKS`]
 193         /// and tracked here.
 194         PendingConnection(VecDeque<OnionMessage>, Option<Vec<SocketAddress>>, usize),
 195 }
 196
 197 impl OnionMessageRecipient {
 198         fn pending_connection(addresses: Vec<SocketAddress>) -> Self {
 199                 Self::PendingConnection(VecDeque::new(), Some(addresses), 0)
 200         }
 201
 202         fn pending_messages(&self) -> &VecDeque<OnionMessage> {
 203                 match self {
 204                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 205                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 206                 }
 207         }
 208
 209         fn enqueue_message(&mut self, message: OnionMessage) {
 210                 let pending_messages = match self {
 211                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 212                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 213                 };
 214
 215                 pending_messages.push_back(message);
 216         }
 217
 218         fn dequeue_message(&mut self) -> Option<OnionMessage> {
 219                 let pending_messages = match self {
 220                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 221                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => {
 222                                 debug_assert!(false);
 223                                 pending_messages
 224                         },
 225                 };
 226
 227                 pending_messages.pop_front()
 228         }
 229
 230         #[cfg(test)]
 231         fn release_pending_messages(&mut self) -> VecDeque<OnionMessage> {
 232                 let pending_messages = match self {
 233                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 234                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 235                 };
 236
 237                 core::mem::take(pending_messages)
 238         }
 239
 240         fn mark_connected(&mut self) {
 241                 if let OnionMessageRecipient::PendingConnection(pending_messages, _, _) = self {
 242                         let mut new_pending_messages = VecDeque::new();
 243                         core::mem::swap(pending_messages, &mut new_pending_messages);
 244                         *self = OnionMessageRecipient::ConnectedPeer(new_pending_messages);
 245                 }
 246         }
 247
 248         fn is_connected(&self) -> bool {
 249                 match self {
 250                         OnionMessageRecipient::ConnectedPeer(..) => true,
 251                         OnionMessageRecipient::PendingConnection(..) => false,
 252                 }
 253         }
 254 }
 255
 256
 257 /// The `Responder` struct creates an appropriate [`ResponseInstruction`]
 258 /// for responding to a message.
 259 pub struct Responder {
 260         /// The path along which a response can be sent.
 261         reply_path: BlindedPath,
 262         path_id: Option<[u8; 32]>
 263 }
 264
 265 impl Responder {
 266         /// Creates a new [`Responder`] instance with the provided reply path.
 267         fn new(reply_path: BlindedPath, path_id: Option<[u8; 32]>) -> Self {
 268                 Responder {
 269                         reply_path,
 270                         path_id,
 271                 }
 272         }
 273
 274         /// Creates the appropriate [`ResponseInstruction`] for a given response.
 275         pub fn respond<T: OnionMessageContents>(self, response: T) -> ResponseInstruction<T> {
 276                 ResponseInstruction::WithoutReplyPath(OnionMessageResponse {
 277                         message: response,
 278                         reply_path: self.reply_path,
 279                         path_id: self.path_id,
 280                 })
 281         }
 282 }
 283
 284 /// This struct contains the information needed to reply to a received message.
 285 pub struct OnionMessageResponse<T: OnionMessageContents> {
 286         message: T,
 287         reply_path: BlindedPath,
 288         path_id: Option<[u8; 32]>,
 289 }
 290
 291 /// `ResponseInstruction` represents instructions for responding to received messages.
 292 pub enum ResponseInstruction<T: OnionMessageContents> {
 293         /// Indicates that a response should be sent without including a reply path
 294         /// for the recipient to respond back.
 295         WithoutReplyPath(OnionMessageResponse<T>),
 296         /// Indicates that there's no response to send back.
 297         NoResponse,
 298 }
 299
 300 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 301 ///
 302 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 303 /// enqueued for sending.
 304 #[cfg(not(c_bindings))]
 305 pub struct PendingOnionMessage<T: OnionMessageContents> {
 306         /// The message contents to send in an [`OnionMessage`].
 307         pub contents: T,
 308
 309         /// The destination of the message.
 310         pub destination: Destination,
 311
 312         /// A reply path to include in the [`OnionMessage`] for a response.
 313         pub reply_path: Option<BlindedPath>,
 314 }
 315
 316 #[cfg(c_bindings)]
 317 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 318 ///
 319 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 320 /// enqueued for sending.
 321 pub type PendingOnionMessage<T> = (T, Destination, Option<BlindedPath>);
 322
 323 pub(crate) fn new_pending_onion_message<T: OnionMessageContents>(
 324         contents: T, destination: Destination, reply_path: Option<BlindedPath>
 325 ) -> PendingOnionMessage<T> {
 326         #[cfg(not(c_bindings))]
 327         return PendingOnionMessage { contents, destination, reply_path };
 328         #[cfg(c_bindings)]
 329         return (contents, destination, reply_path);
 330 }
 331
 332 /// A trait defining behavior for routing an [`OnionMessage`].
 333 pub trait MessageRouter {
 334         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 335         fn find_path(
 336                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 337         ) -> Result<OnionMessagePath, ()>;
 338
 339         /// Creates [`BlindedPath`]s to the `recipient` node. The nodes in `peers` are assumed to be
 340         /// direct peers with the `recipient`.
 341         fn create_blinded_paths<
 342                 T: secp256k1::Signing + secp256k1::Verification
 343         >(
 344                 &self, recipient: PublicKey, peers: Vec<ForwardNode>, secp_ctx: &Secp256k1<T>,
 345         ) -> Result<Vec<BlindedPath>, ()>;
 346 }
 347
 348 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
 349 pub struct DefaultMessageRouter<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref>
 350 where
 351         L::Target: Logger,
 352         ES::Target: EntropySource,
 353 {
 354         network_graph: G,
 355         entropy_source: ES,
 356 }
 357
 358 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> DefaultMessageRouter<G, L, ES>
 359 where
 360         L::Target: Logger,
 361         ES::Target: EntropySource,
 362 {
 363         /// Creates a [`DefaultMessageRouter`] using the given [`NetworkGraph`].
 364         pub fn new(network_graph: G, entropy_source: ES) -> Self {
 365                 Self { network_graph, entropy_source }
 366         }
 367 }
 368
 369 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> MessageRouter for DefaultMessageRouter<G, L, ES>
 370 where
 371         L::Target: Logger,
 372         ES::Target: EntropySource,
 373 {
 374         fn find_path(
 375                 &self, sender: PublicKey, peers: Vec<PublicKey>, mut destination: Destination
 376         ) -> Result<OnionMessagePath, ()> {
 377                 let network_graph = self.network_graph.deref().read_only();
 378                 destination.resolve(&network_graph);
 379
 380                 let first_node = match destination.first_node() {
 381                         Some(first_node) => first_node,
 382                         None => return Err(()),
 383                 };
 384
 385                 if peers.contains(&first_node) || sender == first_node {
 386                         Ok(OnionMessagePath {
 387                                 intermediate_nodes: vec![], destination, first_node_addresses: None
 388                         })
 389                 } else {
 390                         let node_announcement = network_graph
 391                                 .node(&NodeId::from_pubkey(&first_node))
 392                                 .and_then(|node_info| node_info.announcement_info.as_ref())
 393                                 .and_then(|announcement_info| announcement_info.announcement_message.as_ref())
 394                                 .map(|node_announcement| &node_announcement.contents);
 395
 396                         match node_announcement {
 397                                 Some(node_announcement) if node_announcement.features.supports_onion_messages() => {
 398                                         let first_node_addresses = Some(node_announcement.addresses.clone());
 399                                         Ok(OnionMessagePath {
 400                                                 intermediate_nodes: vec![], destination, first_node_addresses
 401                                         })
 402                                 },
 403                                 _ => Err(()),
 404                         }
 405                 }
 406         }
 407
 408         fn create_blinded_paths<
 409                 T: secp256k1::Signing + secp256k1::Verification
 410         >(
 411                 &self, recipient: PublicKey, peers: Vec<ForwardNode>, secp_ctx: &Secp256k1<T>,
 412         ) -> Result<Vec<BlindedPath>, ()> {
 413                 // Limit the number of blinded paths that are computed.
 414                 const MAX_PATHS: usize = 3;
 415
 416                 // Ensure peers have at least three channels so that it is more difficult to infer the
 417                 // recipient's node_id.
 418                 const MIN_PEER_CHANNELS: usize = 3;
 419
 420                 let network_graph = self.network_graph.deref().read_only();
 421                 let is_recipient_announced =
 422                         network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient));
 423
 424                 let mut peer_info = peers.into_iter()
 425                         // Limit to peers with announced channels
 426                         .filter_map(|peer|
 427                                 network_graph
 428                                         .node(&NodeId::from_pubkey(&peer.node_id))
 429                                         .filter(|info| info.channels.len() >= MIN_PEER_CHANNELS)
 430                                         .map(|info| (peer, info.is_tor_only(), info.channels.len()))
 431                         )
 432                         // Exclude Tor-only nodes when the recipient is announced.
 433                         .filter(|(_, is_tor_only, _)| !(*is_tor_only && is_recipient_announced))
 434                         .collect::<Vec<_>>();
 435
 436                 // Prefer using non-Tor nodes with the most channels as the introduction node.
 437                 peer_info.sort_unstable_by(|(_, a_tor_only, a_channels), (_, b_tor_only, b_channels)| {
 438                         a_tor_only.cmp(b_tor_only).then(a_channels.cmp(b_channels).reverse())
 439                 });
 440
 441                 let paths = peer_info.into_iter()
 442                         .map(|(peer, _, _)| {
 443                                 BlindedPath::new_for_message(&[peer], recipient, &*self.entropy_source, secp_ctx)
 444                         })
 445                         .take(MAX_PATHS)
 446                         .collect::<Result<Vec<_>, _>>();
 447
 448                 let mut paths = match paths {
 449                         Ok(paths) if !paths.is_empty() => Ok(paths),
 450                         _ => {
 451                                 if is_recipient_announced {
 452                                         BlindedPath::one_hop_for_message(recipient, &*self.entropy_source, secp_ctx)
 453                                                 .map(|path| vec![path])
 454                                 } else {
 455                                         Err(())
 456                                 }
 457                         },
 458                 }?;
 459                 for path in &mut paths {
 460                         path.use_compact_introduction_node(&network_graph);
 461                 }
 462
 463                 Ok(paths)
 464         }
 465 }
 466
 467 /// A path for sending an [`OnionMessage`].
 468 #[derive(Clone)]
 469 pub struct OnionMessagePath {
 470         /// Nodes on the path between the sender and the destination.
 471         pub intermediate_nodes: Vec<PublicKey>,
 472
 473         /// The recipient of the message.
 474         pub destination: Destination,
 475
 476         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 477         ///
 478         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 479         /// this to initiate such a connection.
 480         pub first_node_addresses: Option<Vec<SocketAddress>>,
 481 }
 482
 483 impl OnionMessagePath {
 484         /// Returns the first node in the path.
 485         pub fn first_node(&self) -> Option<PublicKey> {
 486                 self.intermediate_nodes
 487                         .first()
 488                         .copied()
 489                         .or_else(|| self.destination.first_node())
 490         }
 491 }
 492
 493 /// The destination of an onion message.
 494 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 495 pub enum Destination {
 496         /// We're sending this onion message to a node.
 497         Node(PublicKey),
 498         /// We're sending this onion message to a blinded path.
 499         BlindedPath(BlindedPath),
 500 }
 501
 502 impl Destination {
 503         /// Attempts to resolve the [`IntroductionNode::DirectedShortChannelId`] of a
 504         /// [`Destination::BlindedPath`] to a [`IntroductionNode::NodeId`], if applicable, using the
 505         /// provided [`ReadOnlyNetworkGraph`].
 506         pub fn resolve(&mut self, network_graph: &ReadOnlyNetworkGraph) {
 507                 if let Destination::BlindedPath(path) = self {
 508                         if let IntroductionNode::DirectedShortChannelId(..) = path.introduction_node {
 509                                 if let Some(pubkey) = path
 510                                         .public_introduction_node_id(network_graph)
 511                                         .and_then(|node_id| node_id.as_pubkey().ok())
 512                                 {
 513                                         path.introduction_node = IntroductionNode::NodeId(pubkey);
 514                                 }
 515                         }
 516                 }
 517         }
 518
 519         pub(super) fn num_hops(&self) -> usize {
 520                 match self {
 521                         Destination::Node(_) => 1,
 522                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 523                 }
 524         }
 525
 526         fn first_node(&self) -> Option<PublicKey> {
 527                 match self {
 528                         Destination::Node(node_id) => Some(*node_id),
 529                         Destination::BlindedPath(BlindedPath { introduction_node, .. }) => {
 530                                 match introduction_node {
 531                                         IntroductionNode::NodeId(pubkey) => Some(*pubkey),
 532                                         IntroductionNode::DirectedShortChannelId(..) => None,
 533                                 }
 534                         },
 535                 }
 536         }
 537 }
 538
 539 /// Result of successfully [sending an onion message].
 540 ///
 541 /// [sending an onion message]: OnionMessenger::send_onion_message
 542 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 543 pub enum SendSuccess {
 544         /// The message was buffered and will be sent once it is processed by
 545         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 546         Buffered,
 547         /// The message was buffered and will be sent once the node is connected as a peer and it is
 548         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 549         BufferedAwaitingConnection(PublicKey),
 550 }
 551
 552 /// Errors that may occur when [sending an onion message].
 553 ///
 554 /// [sending an onion message]: OnionMessenger::send_onion_message
 555 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 556 pub enum SendError {
 557         /// Errored computing onion message packet keys.
 558         Secp256k1(secp256k1::Error),
 559         /// Because implementations such as Eclair will drop onion messages where the message packet
 560         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 561         TooBigPacket,
 562         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 563         /// hops.
 564         TooFewBlindedHops,
 565         /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
 566         InvalidFirstHop(PublicKey),
 567         /// A path from the sender to the destination could not be found by the [`MessageRouter`].
 568         PathNotFound,
 569         /// Onion message contents must have a TLV type >= 64.
 570         InvalidMessage,
 571         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 572         BufferFull,
 573         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 574         ///
 575         /// [`NodeSigner`]: crate::sign::NodeSigner
 576         GetNodeIdFailed,
 577         /// The provided [`Destination`] has a blinded path with an unresolved introduction node. An
 578         /// attempt to resolve it in the [`MessageRouter`] when finding an [`OnionMessagePath`] likely
 579         /// failed.
 580         UnresolvedIntroductionNode,
 581         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 582         /// advance the blinded path to make the second hop the new introduction node. Either
 583         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 584         /// new blinding point, or we were attempting to send to ourselves.
 585         BlindedPathAdvanceFailed,
 586 }
 587
 588 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 589 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 590 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 591 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 592 /// message types.
 593 ///
 594 /// See [`OnionMessenger`] for example usage.
 595 ///
 596 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 597 /// [`CustomMessage`]: Self::CustomMessage
 598 pub trait CustomOnionMessageHandler {
 599         /// The message known to the handler. To support multiple message types, you may want to make this
 600         /// an enum with a variant for each supported message.
 601         type CustomMessage: OnionMessageContents;
 602
 603         /// Called with the custom message that was received, returning a response to send, if any.
 604         ///
 605         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 606         fn handle_custom_message(&self, message: Self::CustomMessage, responder: Option<Responder>) -> ResponseInstruction<Self::CustomMessage>;
 607
 608         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 609         /// message type is unknown.
 610         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 611
 612         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 613         ///
 614         /// Typically, this is used for messages initiating a message flow rather than in response to
 615         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 616         #[cfg(not(c_bindings))]
 617         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 618
 619         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 620         ///
 621         /// Typically, this is used for messages initiating a message flow rather than in response to
 622         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 623         #[cfg(c_bindings)]
 624         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 625 }
 626
 627 /// A processed incoming onion message, containing either a Forward (another onion message)
 628 /// or a Receive payload with decrypted contents.
 629 #[derive(Clone, Debug)]
 630 pub enum PeeledOnion<T: OnionMessageContents> {
 631         /// Forwarded onion, with the next node id and a new onion
 632         Forward(NextMessageHop, OnionMessage),
 633         /// Received onion message, with decrypted contents, path_id, and reply path
 634         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 635 }
 636
 637
 638 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 639 /// `path`, first calling [`Destination::resolve`] on `path.destination` with the given
 640 /// [`ReadOnlyNetworkGraph`].
 641 ///
 642 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 643 /// needed to connect to the first node.
 644 pub fn create_onion_message_resolving_destination<
 645         ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents
 646 >(
 647         entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
 648         network_graph: &ReadOnlyNetworkGraph, secp_ctx: &Secp256k1<secp256k1::All>,
 649         mut path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 650 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 651 where
 652         ES::Target: EntropySource,
 653         NS::Target: NodeSigner,
 654         NL::Target: NodeIdLookUp,
 655 {
 656         path.destination.resolve(network_graph);
 657         create_onion_message(
 658                 entropy_source, node_signer, node_id_lookup, secp_ctx, path, contents, reply_path,
 659         )
 660 }
 661
 662 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 663 /// `path`.
 664 ///
 665 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 666 /// needed to connect to the first node.
 667 ///
 668 /// Returns [`SendError::UnresolvedIntroductionNode`] if:
 669 /// - `destination` contains a blinded path with an [`IntroductionNode::DirectedShortChannelId`],
 670 /// - unless it can be resolved by [`NodeIdLookUp::next_node_id`].
 671 /// Use [`create_onion_message_resolving_destination`] instead to resolve the introduction node
 672 /// first with a [`ReadOnlyNetworkGraph`].
 673 pub fn create_onion_message<ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents>(
 674         entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
 675         secp_ctx: &Secp256k1<secp256k1::All>, path: OnionMessagePath, contents: T,
 676         reply_path: Option<BlindedPath>,
 677 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 678 where
 679         ES::Target: EntropySource,
 680         NS::Target: NodeSigner,
 681         NL::Target: NodeIdLookUp,
 682 {
 683         let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
 684         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 685                 if blinded_hops.is_empty() {
 686                         return Err(SendError::TooFewBlindedHops);
 687                 }
 688         }
 689
 690         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 691
 692         // If we are sending straight to a blinded path and we are the introduction node, we need to
 693         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 694         if intermediate_nodes.len() == 0 {
 695                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 696                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 697                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 698                         let introduction_node_id = match blinded_path.introduction_node {
 699                                 IntroductionNode::NodeId(pubkey) => pubkey,
 700                                 IntroductionNode::DirectedShortChannelId(direction, scid) => {
 701                                         match node_id_lookup.next_node_id(scid) {
 702                                                 Some(next_node_id) => *direction.select_pubkey(&our_node_id, &next_node_id),
 703                                                 None => return Err(SendError::UnresolvedIntroductionNode),
 704                                         }
 705                                 },
 706                         };
 707                         if introduction_node_id == our_node_id {
 708                                 advance_path_by_one(blinded_path, node_signer, node_id_lookup, &secp_ctx)
 709                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 710                         }
 711                 }
 712         }
 713
 714         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 715         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 716         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 717                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 718         } else {
 719                 match &destination {
 720                         Destination::Node(pk) => (*pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 721                         Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, .. }) => {
 722                                 match introduction_node {
 723                                         IntroductionNode::NodeId(pubkey) => (*pubkey, *blinding_point),
 724                                         IntroductionNode::DirectedShortChannelId(..) => {
 725                                                 return Err(SendError::UnresolvedIntroductionNode);
 726                                         },
 727                                 }
 728                         }
 729                 }
 730         };
 731         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 732                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret
 733         )?;
 734
 735         let prng_seed = entropy_source.get_secure_random_bytes();
 736         let onion_routing_packet = construct_onion_message_packet(
 737                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 738
 739         let message = OnionMessage { blinding_point, onion_routing_packet };
 740         Ok((first_node_id, message, first_node_addresses))
 741 }
 742
 743 /// Decode one layer of an incoming [`OnionMessage`].
 744 ///
 745 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 746 /// receiver.
 747 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 748         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 749         custom_handler: CMH,
 750 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 751 where
 752         NS::Target: NodeSigner,
 753         L::Target: Logger,
 754         CMH::Target: CustomOnionMessageHandler,
 755 {
 756         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 757                 Ok(ss) => ss,
 758                 Err(e) =>  {
 759                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 760                         return Err(());
 761                 }
 762         };
 763         let onion_decode_ss = {
 764                 let blinding_factor = {
 765                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 766                         hmac.input(control_tlvs_ss.as_ref());
 767                         Hmac::from_engine(hmac).to_byte_array()
 768                 };
 769                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 770                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 771                 {
 772                         Ok(ss) => ss.secret_bytes(),
 773                         Err(()) => {
 774                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 775                                 return Err(());
 776                         }
 777                 }
 778         };
 779         match onion_utils::decode_next_untagged_hop(
 780                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 781                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 782         ) {
 783                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 784                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 785                 }, None)) => {
 786                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 787                 },
 788                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 789                         next_hop, next_blinding_override
 790                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 791                         // TODO: we need to check whether `next_hop` is our node, in which case this is a dummy
 792                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 793                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 794                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 795                         // for now.
 796                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 797                                 Ok(pk) => pk,
 798                                 Err(e) => {
 799                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 800                                         return Err(())
 801                                 }
 802                         };
 803                         let outgoing_packet = Packet {
 804                                 version: 0,
 805                                 public_key: new_pubkey,
 806                                 hop_data: new_packet_bytes,
 807                                 hmac: next_hop_hmac,
 808                         };
 809                         let onion_message = OnionMessage {
 810                                 blinding_point: match next_blinding_override {
 811                                         Some(blinding_point) => blinding_point,
 812                                         None => {
 813                                                 match onion_utils::next_hop_pubkey(
 814                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 815                                                 ) {
 816                                                         Ok(bp) => bp,
 817                                                         Err(e) => {
 818                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 819                                                                 return Err(())
 820                                                         }
 821                                                 }
 822                                         }
 823                                 },
 824                                 onion_routing_packet: outgoing_packet,
 825                         };
 826
 827                         Ok(PeeledOnion::Forward(next_hop, onion_message))
 828                 },
 829                 Err(e) => {
 830                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 831                         Err(())
 832                 },
 833                 _ => {
 834                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 835                         Err(())
 836                 },
 837         }
 838 }
 839
 840 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 841 OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
 842 where
 843         ES::Target: EntropySource,
 844         NS::Target: NodeSigner,
 845         L::Target: Logger,
 846         NL::Target: NodeIdLookUp,
 847         MR::Target: MessageRouter,
 848         OMH::Target: OffersMessageHandler,
 849         CMH::Target: CustomOnionMessageHandler,
 850 {
 851         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 852         /// their respective handlers.
 853         pub fn new(
 854                 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL, message_router: MR,
 855                 offers_handler: OMH, custom_handler: CMH
 856         ) -> Self {
 857                 Self::new_inner(
 858                         entropy_source, node_signer, logger, node_id_lookup, message_router,
 859                         offers_handler, custom_handler, false
 860                 )
 861         }
 862
 863         /// Similar to [`Self::new`], but rather than dropping onion messages that are
 864         /// intended to be forwarded to offline peers, we will intercept them for
 865         /// later forwarding.
 866         ///
 867         /// Interception flow:
 868         /// 1. If an onion message for an offline peer is received, `OnionMessenger` will
 869         ///    generate an [`Event::OnionMessageIntercepted`]. Event handlers can
 870         ///    then choose to persist this onion message for later forwarding, or drop
 871         ///    it.
 872         /// 2. When the offline peer later comes back online, `OnionMessenger` will
 873         ///    generate an [`Event::OnionMessagePeerConnected`]. Event handlers will
 874         ///    then fetch all previously intercepted onion messages for this peer.
 875         /// 3. Once the stored onion messages are fetched, they can finally be
 876         ///    forwarded to the now-online peer via [`Self::forward_onion_message`].
 877         ///
 878         /// # Note
 879         ///
 880         /// LDK will not rate limit how many [`Event::OnionMessageIntercepted`]s
 881         /// are generated, so it is the caller's responsibility to limit how many
 882         /// onion messages are persisted and only persist onion messages for relevant
 883         /// peers.
 884         pub fn new_with_offline_peer_interception(
 885                 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL,
 886                 message_router: MR, offers_handler: OMH, custom_handler: CMH
 887         ) -> Self {
 888                 Self::new_inner(
 889                         entropy_source, node_signer, logger, node_id_lookup, message_router,
 890                         offers_handler, custom_handler, true
 891                 )
 892         }
 893
 894         fn new_inner(
 895                 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL,
 896                 message_router: MR, offers_handler: OMH, custom_handler: CMH,
 897                 intercept_messages_for_offline_peers: bool
 898         ) -> Self {
 899                 let mut secp_ctx = Secp256k1::new();
 900                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 901                 OnionMessenger {
 902                         entropy_source,
 903                         node_signer,
 904                         message_recipients: Mutex::new(new_hash_map()),
 905                         secp_ctx,
 906                         logger,
 907                         node_id_lookup,
 908                         message_router,
 909                         offers_handler,
 910                         custom_handler,
 911                         intercept_messages_for_offline_peers,
 912                         pending_events: Mutex::new(Vec::new()),
 913                 }
 914         }
 915
 916         #[cfg(test)]
 917         pub(crate) fn set_offers_handler(&mut self, offers_handler: OMH) {
 918                 self.offers_handler = offers_handler;
 919         }
 920
 921         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
 922         ///
 923         /// See [`OnionMessenger`] for example usage.
 924         pub fn send_onion_message<T: OnionMessageContents>(
 925                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
 926         ) -> Result<SendSuccess, SendError> {
 927                 self.find_path_and_enqueue_onion_message(
 928                         contents, destination, reply_path, format_args!("")
 929                 )
 930         }
 931
 932         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 933                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 934                 log_suffix: fmt::Arguments
 935         ) -> Result<SendSuccess, SendError> {
 936                 let mut logger = WithContext::from(&self.logger, None, None, None);
 937                 let result = self.find_path(destination).and_then(|path| {
 938                         let first_hop = path.intermediate_nodes.get(0).map(|p| *p);
 939                         logger = WithContext::from(&self.logger, first_hop, None, None);
 940                         self.enqueue_onion_message(path, contents, reply_path, log_suffix)
 941                 });
 942
 943                 match result.as_ref() {
 944                         Err(SendError::GetNodeIdFailed) => {
 945                                 log_warn!(logger, "Unable to retrieve node id {}", log_suffix);
 946                         },
 947                         Err(SendError::PathNotFound) => {
 948                                 log_trace!(logger, "Failed to find path {}", log_suffix);
 949                         },
 950                         Err(e) => {
 951                                 log_trace!(logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 952                         },
 953                         Ok(SendSuccess::Buffered) => {
 954                                 log_trace!(logger, "Buffered onion message {}", log_suffix);
 955                         },
 956                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
 957                                 log_trace!(
 958                                         logger,
 959                                         "Buffered onion message waiting on peer connection {}: {}",
 960                                         log_suffix, node_id
 961                                 );
 962                         },
 963                 }
 964
 965                 result
 966         }
 967
 968         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
 969                 let sender = self.node_signer
 970                         .get_node_id(Recipient::Node)
 971                         .map_err(|_| SendError::GetNodeIdFailed)?;
 972
 973                 let peers = self.message_recipients.lock().unwrap()
 974                         .iter()
 975                         .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
 976                         .map(|(node_id, _)| *node_id)
 977                         .collect();
 978
 979                 self.message_router
 980                         .find_path(sender, peers, destination)
 981                         .map_err(|_| SendError::PathNotFound)
 982         }
 983
 984         fn enqueue_onion_message<T: OnionMessageContents>(
 985                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 986                 log_suffix: fmt::Arguments
 987         ) -> Result<SendSuccess, SendError> {
 988                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 989
 990                 let (first_node_id, onion_message, addresses) = create_onion_message(
 991                         &self.entropy_source, &self.node_signer, &self.node_id_lookup, &self.secp_ctx, path,
 992                         contents, reply_path,
 993                 )?;
 994
 995                 let mut message_recipients = self.message_recipients.lock().unwrap();
 996                 if outbound_buffer_full(&first_node_id, &message_recipients) {
 997                         return Err(SendError::BufferFull);
 998                 }
 999
1000                 match message_recipients.entry(first_node_id) {
1001                         hash_map::Entry::Vacant(e) => match addresses {
1002                                 None => Err(SendError::InvalidFirstHop(first_node_id)),
1003                                 Some(addresses) => {
1004                                         e.insert(OnionMessageRecipient::pending_connection(addresses))
1005                                                 .enqueue_message(onion_message);
1006                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
1007                                 },
1008                         },
1009                         hash_map::Entry::Occupied(mut e) => {
1010                                 e.get_mut().enqueue_message(onion_message);
1011                                 if e.get().is_connected() {
1012                                         Ok(SendSuccess::Buffered)
1013                                 } else {
1014                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
1015                                 }
1016                         },
1017                 }
1018         }
1019
1020         /// Forwards an [`OnionMessage`] to `peer_node_id`. Useful if we initialized
1021         /// the [`OnionMessenger`] with [`Self::new_with_offline_peer_interception`]
1022         /// and want to forward a previously intercepted onion message to a peer that
1023         /// has just come online.
1024         pub fn forward_onion_message(
1025                 &self, message: OnionMessage, peer_node_id: &PublicKey
1026         ) -> Result<(), SendError> {
1027                 let mut message_recipients = self.message_recipients.lock().unwrap();
1028                 if outbound_buffer_full(&peer_node_id, &message_recipients) {
1029                         return Err(SendError::BufferFull);
1030                 }
1031
1032                 match message_recipients.entry(*peer_node_id) {
1033                         hash_map::Entry::Occupied(mut e) if e.get().is_connected() => {
1034                                 e.get_mut().enqueue_message(message);
1035                                 Ok(())
1036                         },
1037                         _ => Err(SendError::InvalidFirstHop(*peer_node_id))
1038                 }
1039         }
1040
1041         #[cfg(any(test, feature = "_test_utils"))]
1042         pub fn send_onion_message_using_path<T: OnionMessageContents>(
1043                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
1044         ) -> Result<SendSuccess, SendError> {
1045                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
1046         }
1047
1048         pub(crate) fn peel_onion_message(
1049                 &self, msg: &OnionMessage
1050         ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()> {
1051                 peel_onion_message(
1052                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
1053                 )
1054         }
1055
1056         fn handle_onion_message_response<T: OnionMessageContents>(
1057                 &self, response: ResponseInstruction<T>
1058         ) {
1059                 if let ResponseInstruction::WithoutReplyPath(response) = response {
1060                         let message_type = response.message.msg_type();
1061                         let _ = self.find_path_and_enqueue_onion_message(
1062                                 response.message, Destination::BlindedPath(response.reply_path), None,
1063                                 format_args!(
1064                                         "when responding with {} to an onion message with path_id {:02x?}",
1065                                         message_type,
1066                                         response.path_id
1067                                 )
1068                         );
1069                 }
1070         }
1071
1072         #[cfg(test)]
1073         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
1074                 let mut message_recipients = self.message_recipients.lock().unwrap();
1075                 let mut msgs = new_hash_map();
1076                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
1077                 // release the pending message buffers individually.
1078                 for (node_id, recipient) in &mut *message_recipients {
1079                         msgs.insert(*node_id, recipient.release_pending_messages());
1080                 }
1081                 msgs
1082         }
1083
1084         fn enqueue_event(&self, event: Event) {
1085                 const MAX_EVENTS_BUFFER_SIZE: usize = (1 << 10) * 256;
1086                 let mut pending_events = self.pending_events.lock().unwrap();
1087                 let total_buffered_bytes: usize = pending_events
1088                         .iter()
1089                         .map(|ev| ev.serialized_length())
1090                         .sum();
1091                 if total_buffered_bytes >= MAX_EVENTS_BUFFER_SIZE {
1092                         log_trace!(self.logger, "Dropping event {:?}: buffer full", event);
1093                         return
1094                 }
1095                 pending_events.push(event);
1096         }
1097 }
1098
1099 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
1100         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
1101         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
1102         let mut total_buffered_bytes = 0;
1103         let mut peer_buffered_bytes = 0;
1104         for (pk, peer_buf) in buffer {
1105                 for om in peer_buf.pending_messages() {
1106                         let om_len = om.serialized_length();
1107                         if pk == peer_node_id {
1108                                 peer_buffered_bytes += om_len;
1109                         }
1110                         total_buffered_bytes += om_len;
1111
1112                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
1113                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
1114                         {
1115                                 return true
1116                         }
1117                 }
1118         }
1119         false
1120 }
1121
1122 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
1123 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
1124 where
1125         ES::Target: EntropySource,
1126         NS::Target: NodeSigner,
1127         L::Target: Logger,
1128         NL::Target: NodeIdLookUp,
1129         MR::Target: MessageRouter,
1130         OMH::Target: OffersMessageHandler,
1131         CMH::Target: CustomOnionMessageHandler,
1132 {
1133         fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
1134                 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
1135                         if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
1136                                 if let Some(addresses) = addresses.take() {
1137                                         handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
1138                                 }
1139                         }
1140                 }
1141                 let mut events = Vec::new();
1142                 core::mem::swap(&mut *self.pending_events.lock().unwrap(), &mut events);
1143                 for ev in events {
1144                         handler.handle_event(ev);
1145                 }
1146         }
1147 }
1148
1149 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
1150 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
1151 where
1152         ES::Target: EntropySource,
1153         NS::Target: NodeSigner,
1154         L::Target: Logger,
1155         NL::Target: NodeIdLookUp,
1156         MR::Target: MessageRouter,
1157         OMH::Target: OffersMessageHandler,
1158         CMH::Target: CustomOnionMessageHandler,
1159 {
1160         fn handle_onion_message(&self, peer_node_id: &PublicKey, msg: &OnionMessage) {
1161                 let logger = WithContext::from(&self.logger, Some(*peer_node_id), None, None);
1162                 match self.peel_onion_message(msg) {
1163                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
1164                                 log_trace!(
1165                                         logger,
1166                                         "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
1167                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
1168
1169                                 match message {
1170                                         ParsedOnionMessageContents::Offers(msg) => {
1171                                                 let responder = reply_path.map(
1172                                                         |reply_path| Responder::new(reply_path, path_id)
1173                                                 );
1174                                                 let response_instructions = self.offers_handler.handle_message(msg, responder);
1175                                                 self.handle_onion_message_response(response_instructions);
1176                                         },
1177                                         ParsedOnionMessageContents::Custom(msg) => {
1178                                                 let responder = reply_path.map(
1179                                                         |reply_path| Responder::new(reply_path, path_id)
1180                                                 );
1181                                                 let response_instructions = self.custom_handler.handle_custom_message(msg, responder);
1182                                                 self.handle_onion_message_response(response_instructions);
1183                                         },
1184                                 }
1185                         },
1186                         Ok(PeeledOnion::Forward(next_hop, onion_message)) => {
1187                                 let next_node_id = match next_hop {
1188                                         NextMessageHop::NodeId(pubkey) => pubkey,
1189                                         NextMessageHop::ShortChannelId(scid) => match self.node_id_lookup.next_node_id(scid) {
1190                                                 Some(pubkey) => pubkey,
1191                                                 None => {
1192                                                         log_trace!(self.logger, "Dropping forwarded onion messager: unable to resolve next hop using SCID {}", scid);
1193                                                         return
1194                                                 },
1195                                         },
1196                                 };
1197
1198                                 let mut message_recipients = self.message_recipients.lock().unwrap();
1199                                 if outbound_buffer_full(&next_node_id, &message_recipients) {
1200                                         log_trace!(
1201                                                 logger,
1202                                                 "Dropping forwarded onion message to peer {}: outbound buffer full",
1203                                                 next_node_id);
1204                                         return
1205                                 }
1206
1207                                 #[cfg(fuzzing)]
1208                                 message_recipients
1209                                         .entry(next_node_id)
1210                                         .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
1211
1212                                 match message_recipients.entry(next_node_id) {
1213                                         hash_map::Entry::Occupied(mut e) if matches!(
1214                                                 e.get(), OnionMessageRecipient::ConnectedPeer(..)
1215                                         ) => {
1216                                                 e.get_mut().enqueue_message(onion_message);
1217                                                 log_trace!(logger, "Forwarding an onion message to peer {}", next_node_id);
1218                                         },
1219                                         _ if self.intercept_messages_for_offline_peers => {
1220                                                 self.enqueue_event(
1221                                                         Event::OnionMessageIntercepted {
1222                                                                 peer_node_id: next_node_id, message: onion_message
1223                                                         }
1224                                                 );
1225                                         },
1226                                         _ => {
1227                                                 log_trace!(
1228                                                         logger,
1229                                                         "Dropping forwarded onion message to disconnected peer {}",
1230                                                         next_node_id);
1231                                                 return
1232                                         },
1233                                 }
1234                         },
1235                         Err(e) => {
1236                                 log_error!(logger, "Failed to process onion message {:?}", e);
1237                         }
1238                 }
1239         }
1240
1241         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
1242                 if init.features.supports_onion_messages() {
1243                         self.message_recipients.lock().unwrap()
1244                                 .entry(*their_node_id)
1245                                 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
1246                                 .mark_connected();
1247                         if self.intercept_messages_for_offline_peers {
1248                                 self.enqueue_event(
1249                                         Event::OnionMessagePeerConnected { peer_node_id: *their_node_id }
1250                                 );
1251                         }
1252                 } else {
1253                         self.message_recipients.lock().unwrap().remove(their_node_id);
1254                 }
1255
1256                 Ok(())
1257         }
1258
1259         fn peer_disconnected(&self, their_node_id: &PublicKey) {
1260                 match self.message_recipients.lock().unwrap().remove(their_node_id) {
1261                         Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
1262                         Some(_) => debug_assert!(false),
1263                         None => {},
1264                 }
1265         }
1266
1267         fn timer_tick_occurred(&self) {
1268                 let mut message_recipients = self.message_recipients.lock().unwrap();
1269
1270                 // Drop any pending recipients since the last call to avoid retaining buffered messages for
1271                 // too long.
1272                 message_recipients.retain(|_, recipient| match recipient {
1273                         OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
1274                         OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
1275                         _ => true,
1276                 });
1277
1278                 // Increment a timer tick for pending recipients so that their buffered messages are dropped
1279                 // at MAX_TIMER_TICKS.
1280                 for recipient in message_recipients.values_mut() {
1281                         if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
1282                                 *ticks += 1;
1283                         }
1284                 }
1285         }
1286
1287         fn provided_node_features(&self) -> NodeFeatures {
1288                 let mut features = NodeFeatures::empty();
1289                 features.set_onion_messages_optional();
1290                 features
1291         }
1292
1293         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1294                 let mut features = InitFeatures::empty();
1295                 features.set_onion_messages_optional();
1296                 features
1297         }
1298
1299         // Before returning any messages to send for the peer, this method will see if any messages were
1300         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1301         // node, and then enqueue the message for sending to the first peer in the full path.
1302         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1303                 // Enqueue any initiating `OffersMessage`s to send.
1304                 for message in self.offers_handler.release_pending_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 OffersMessage")
1311                         );
1312                 }
1313
1314                 // Enqueue any initiating `CustomMessage`s to send.
1315                 for message in self.custom_handler.release_pending_custom_messages() {
1316                         #[cfg(not(c_bindings))]
1317                         let PendingOnionMessage { contents, destination, reply_path } = message;
1318                         #[cfg(c_bindings)]
1319                         let (contents, destination, reply_path) = message;
1320                         let _ = self.find_path_and_enqueue_onion_message(
1321                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
1322                         );
1323                 }
1324
1325                 self.message_recipients.lock().unwrap()
1326                         .get_mut(&peer_node_id)
1327                         .and_then(|buffer| buffer.dequeue_message())
1328         }
1329 }
1330
1331 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1332 // produces
1333 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1334 /// [`SimpleArcPeerManager`]. See their docs for more details.
1335 ///
1336 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1337 ///
1338 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1339 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1340 #[cfg(not(c_bindings))]
1341 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1342         Arc<KeysManager>,
1343         Arc<KeysManager>,
1344         Arc<L>,
1345         Arc<SimpleArcChannelManager<M, T, F, L>>,
1346         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>, Arc<KeysManager>>>,
1347         Arc<SimpleArcChannelManager<M, T, F, L>>,
1348         IgnoringMessageHandler
1349 >;
1350
1351 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1352 /// [`SimpleRefPeerManager`]. See their docs for more details.
1353 ///
1354 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1355 ///
1356 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1357 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1358 #[cfg(not(c_bindings))]
1359 pub type SimpleRefOnionMessenger<
1360         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1361 > = OnionMessenger<
1362         &'a KeysManager,
1363         &'a KeysManager,
1364         &'b L,
1365         &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1366         &'j DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L, &'a KeysManager>,
1367         &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1368         IgnoringMessageHandler
1369 >;
1370
1371 /// Construct onion packet payloads and keys for sending an onion message along the given
1372 /// `unblinded_path` to the given `destination`.
1373 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1374         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1375         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1376 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), SendError> {
1377         let num_hops = unblinded_path.len() + destination.num_hops();
1378         let mut payloads = Vec::with_capacity(num_hops);
1379         let mut onion_packet_keys = Vec::with_capacity(num_hops);
1380
1381         let (mut intro_node_id_blinding_pt, num_blinded_hops) = match &destination {
1382                 Destination::Node(_) => (None, 0),
1383                 Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, blinded_hops }) => {
1384                         let introduction_node_id = match introduction_node {
1385                                 IntroductionNode::NodeId(pubkey) => pubkey,
1386                                 IntroductionNode::DirectedShortChannelId(..) => {
1387                                         return Err(SendError::UnresolvedIntroductionNode);
1388                                 },
1389                         };
1390                         (Some((*introduction_node_id, *blinding_point)), blinded_hops.len())
1391                 },
1392         };
1393         let num_unblinded_hops = num_hops - num_blinded_hops;
1394
1395         let mut unblinded_path_idx = 0;
1396         let mut blinded_path_idx = 0;
1397         let mut prev_control_tlvs_ss = None;
1398         let mut final_control_tlvs = None;
1399         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1400                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1401                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1402                                 if let Some(ss) = prev_control_tlvs_ss.take() {
1403                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1404                                                 ForwardTlvs {
1405                                                         next_hop: NextMessageHop::NodeId(unblinded_pk_opt.unwrap()),
1406                                                         next_blinding_override: None,
1407                                                 }
1408                                         )), ss));
1409                                 }
1410                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1411                                 unblinded_path_idx += 1;
1412                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1413                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1414                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1415                                                 next_hop: NextMessageHop::NodeId(intro_node_id),
1416                                                 next_blinding_override: Some(blinding_pt),
1417                                         })), control_tlvs_ss));
1418                                 }
1419                         }
1420                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1421                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1422                                         control_tlvs_ss));
1423                                 blinded_path_idx += 1;
1424                         } else if let Some(encrypted_payload) = enc_payload_opt {
1425                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1426                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1427                         }
1428
1429                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1430                         onion_packet_keys.push(onion_utils::OnionKeys {
1431                                 #[cfg(test)]
1432                                 shared_secret: onion_packet_ss,
1433                                 #[cfg(test)]
1434                                 blinding_factor: [0; 32],
1435                                 ephemeral_pubkey,
1436                                 rho,
1437                                 mu,
1438                         });
1439                 }
1440         ).map_err(|e| SendError::Secp256k1(e))?;
1441
1442         if let Some(control_tlvs) = final_control_tlvs {
1443                 payloads.push((Payload::Receive {
1444                         control_tlvs,
1445                         reply_path: reply_path.take(),
1446                         message,
1447                 }, prev_control_tlvs_ss.unwrap()));
1448         } else {
1449                 payloads.push((Payload::Receive {
1450                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1451                         reply_path: reply_path.take(),
1452                         message,
1453                 }, prev_control_tlvs_ss.unwrap()));
1454         }
1455
1456         Ok((payloads, onion_packet_keys))
1457 }
1458
1459 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1460 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, ()> {
1461         // Spec rationale:
1462         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1463         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1464         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1465         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1466         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1467                 SMALL_PACKET_HOP_DATA_LEN
1468         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1469                 BIG_PACKET_HOP_DATA_LEN
1470         } else { return Err(()) };
1471
1472         onion_utils::construct_onion_message_packet::<_, _>(
1473                 payloads, onion_keys, prng_seed, hop_data_len)
1474 }