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