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