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