_ Git - rust-lightning/blob - lightning/src/onion_message/messenger.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! LDK sends, receives, and forwards onion messages via this [`OnionMessenger`], which lives here,
  11 //! as well as various types, traits, and utilities that it uses.
  12
  13 use bitcoin::hashes::{Hash, HashEngine};
  14 use bitcoin::hashes::hmac::{Hmac, HmacEngine};
  15 use bitcoin::hashes::sha256::Hash as Sha256;
  16 use bitcoin::secp256k1::{self, PublicKey, Scalar, Secp256k1, SecretKey};
  17
  18 use crate::blinded_path::{BlindedPath, IntroductionNode, NextMessageHop, NodeIdLookUp};
  19 use crate::blinded_path::message::{advance_path_by_one, ForwardNode, ForwardTlvs, ReceiveTlvs};
  20 use crate::blinded_path::utils;
  21 use crate::events::{Event, EventHandler, EventsProvider};
  22 use crate::sign::{EntropySource, NodeSigner, Recipient};
  23 use crate::ln::features::{InitFeatures, NodeFeatures};
  24 use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler, SocketAddress};
  25 use crate::ln::onion_utils;
  26 use crate::routing::gossip::{NetworkGraph, NodeId, ReadOnlyNetworkGraph};
  27 use super::packet::OnionMessageContents;
  28 use super::packet::ParsedOnionMessageContents;
  29 use super::offers::OffersMessageHandler;
  30 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  31 use crate::util::logger::{Logger, WithContext};
  32 use crate::util::ser::Writeable;
  33
  34 use core::fmt;
  35 use core::ops::Deref;
  36 use crate::io;
  37 use crate::sync::Mutex;
  38 use crate::prelude::*;
  39
  40 #[cfg(not(c_bindings))]
  41 use {
  42         crate::sign::KeysManager,
  43         crate::ln::channelmanager::{SimpleArcChannelManager, SimpleRefChannelManager},
  44         crate::ln::peer_handler::IgnoringMessageHandler,
  45         crate::sync::Arc,
  46 };
  47
  48 pub(super) const MAX_TIMER_TICKS: usize = 2;
  49
  50 /// A trivial trait which describes any [`OnionMessenger`].
  51 ///
  52 /// This is not exported to bindings users as general cover traits aren't useful in other
  53 /// languages.
  54 pub trait AOnionMessenger {
  55         /// A type implementing [`EntropySource`]
  56         type EntropySource: EntropySource + ?Sized;
  57         /// A type that may be dereferenced to [`Self::EntropySource`]
  58         type ES: Deref<Target = Self::EntropySource>;
  59         /// A type implementing [`NodeSigner`]
  60         type NodeSigner: NodeSigner + ?Sized;
  61         /// A type that may be dereferenced to [`Self::NodeSigner`]
  62         type NS: Deref<Target = Self::NodeSigner>;
  63         /// A type implementing [`Logger`]
  64         type Logger: Logger + ?Sized;
  65         /// A type that may be dereferenced to [`Self::Logger`]
  66         type L: Deref<Target = Self::Logger>;
  67         /// A type implementing [`NodeIdLookUp`]
  68         type NodeIdLookUp: NodeIdLookUp + ?Sized;
  69         /// A type that may be dereferenced to [`Self::NodeIdLookUp`]
  70         type NL: Deref<Target = Self::NodeIdLookUp>;
  71         /// A type implementing [`MessageRouter`]
  72         type MessageRouter: MessageRouter + ?Sized;
  73         /// A type that may be dereferenced to [`Self::MessageRouter`]
  74         type MR: Deref<Target = Self::MessageRouter>;
  75         /// A type implementing [`OffersMessageHandler`]
  76         type OffersMessageHandler: OffersMessageHandler + ?Sized;
  77         /// A type that may be dereferenced to [`Self::OffersMessageHandler`]
  78         type OMH: Deref<Target = Self::OffersMessageHandler>;
  79         /// A type implementing [`CustomOnionMessageHandler`]
  80         type CustomOnionMessageHandler: CustomOnionMessageHandler + ?Sized;
  81         /// A type that may be dereferenced to [`Self::CustomOnionMessageHandler`]
  82         type CMH: Deref<Target = Self::CustomOnionMessageHandler>;
  83         /// Returns a reference to the actual [`OnionMessenger`] object.
  84         fn get_om(&self) -> &OnionMessenger<Self::ES, Self::NS, Self::L, Self::NL, Self::MR, Self::OMH, Self::CMH>;
  85 }
  86
  87 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> AOnionMessenger
  88 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH> where
  89         ES::Target: EntropySource,
  90         NS::Target: NodeSigner,
  91         L::Target: Logger,
  92         NL::Target: NodeIdLookUp,
  93         MR::Target: MessageRouter,
  94         OMH::Target: OffersMessageHandler,
  95         CMH::Target: CustomOnionMessageHandler,
  96 {
  97         type EntropySource = ES::Target;
  98         type ES = ES;
  99         type NodeSigner = NS::Target;
 100         type NS = NS;
 101         type Logger = L::Target;
 102         type L = L;
 103         type NodeIdLookUp = NL::Target;
 104         type NL = NL;
 105         type MessageRouter = MR::Target;
 106         type MR = MR;
 107         type OffersMessageHandler = OMH::Target;
 108         type OMH = OMH;
 109         type CustomOnionMessageHandler = CMH::Target;
 110         type CMH = CMH;
 111         fn get_om(&self) -> &OnionMessenger<ES, NS, L, NL, MR, OMH, CMH> { self }
 112 }
 113
 114 /// A sender, receiver and forwarder of [`OnionMessage`]s.
 115 ///
 116 /// # Handling Messages
 117 ///
 118 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
 119 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
 120 /// available handlers are:
 121 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
 122 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
 123 ///
 124 /// # Sending Messages
 125 ///
 126 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
 127 /// a message, the matched handler may return a response message which `OnionMessenger` will send
 128 /// on its behalf.
 129 ///
 130 /// # Example
 131 ///
 132 /// ```
 133 /// # extern crate bitcoin;
 134 /// # use bitcoin::hashes::_export::_core::time::Duration;
 135 /// # use bitcoin::hashes::hex::FromHex;
 136 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey, self};
 137 /// # use lightning::blinded_path::{BlindedPath, EmptyNodeIdLookUp};
 138 /// # use lightning::blinded_path::message::ForwardNode;
 139 /// # use lightning::sign::{EntropySource, KeysManager};
 140 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
 141 /// # use lightning::onion_message::messenger::{Destination, MessageRouter, OnionMessagePath, OnionMessenger};
 142 /// # use lightning::onion_message::packet::OnionMessageContents;
 143 /// # use lightning::util::logger::{Logger, Record};
 144 /// # use lightning::util::ser::{Writeable, Writer};
 145 /// # use lightning::io;
 146 /// # use std::sync::Arc;
 147 /// # struct FakeLogger;
 148 /// # impl Logger for FakeLogger {
 149 /// #     fn log(&self, record: Record) { println!("{:?}" , record); }
 150 /// # }
 151 /// # struct FakeMessageRouter {}
 152 /// # impl MessageRouter for FakeMessageRouter {
 153 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
 154 /// #         let secp_ctx = Secp256k1::new();
 155 /// #         let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
 156 /// #         let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
 157 /// #         let hop_node_id2 = hop_node_id1;
 158 /// #         Ok(OnionMessagePath {
 159 /// #             intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 160 /// #             destination,
 161 /// #             first_node_addresses: None,
 162 /// #         })
 163 /// #     }
 164 /// #     fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
 165 /// #         &self, _recipient: PublicKey, _peers: Vec<PublicKey>, _secp_ctx: &Secp256k1<T>
 166 /// #     ) -> Result<Vec<BlindedPath>, ()> {
 167 /// #         unreachable!()
 168 /// #     }
 169 /// # }
 170 /// # let seed = [42u8; 32];
 171 /// # let time = Duration::from_secs(123456);
 172 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
 173 /// # let logger = Arc::new(FakeLogger {});
 174 /// # let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
 175 /// # let secp_ctx = Secp256k1::new();
 176 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
 177 /// # let (hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1);
 178 /// # let destination_node_id = hop_node_id1;
 179 /// # let node_id_lookup = EmptyNodeIdLookUp {};
 180 /// # let message_router = Arc::new(FakeMessageRouter {});
 181 /// # let custom_message_handler = IgnoringMessageHandler {};
 182 /// # let offers_message_handler = IgnoringMessageHandler {};
 183 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
 184 /// // ChannelManager.
 185 /// let onion_messenger = OnionMessenger::new(
 186 ///     &keys_manager, &keys_manager, logger, &node_id_lookup, message_router,
 187 ///     &offers_message_handler, &custom_message_handler
 188 /// );
 189
 190 /// # #[derive(Debug)]
 191 /// # struct YourCustomMessage {}
 192 /// impl Writeable for YourCustomMessage {
 193 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 194 ///             # Ok(())
 195 ///             // Write your custom onion message to `w`
 196 ///     }
 197 /// }
 198 /// impl OnionMessageContents for YourCustomMessage {
 199 ///     fn tlv_type(&self) -> u64 {
 200 ///             # let your_custom_message_type = 42;
 201 ///             your_custom_message_type
 202 ///     }
 203 ///     fn msg_type(&self) -> &'static str { "YourCustomMessageType" }
 204 /// }
 205 /// // Send a custom onion message to a node id.
 206 /// let destination = Destination::Node(destination_node_id);
 207 /// let reply_path = None;
 208 /// # let message = YourCustomMessage {};
 209 /// onion_messenger.send_onion_message(message, destination, reply_path);
 210 ///
 211 /// // Create a blinded path to yourself, for someone to send an onion message to.
 212 /// # let your_node_id = hop_node_id1;
 213 /// let hops = [
 214 ///     ForwardNode { node_id: hop_node_id3, short_channel_id: None },
 215 ///     ForwardNode { node_id: hop_node_id4, short_channel_id: None },
 216 /// ];
 217 /// let blinded_path = BlindedPath::new_for_message(&hops, your_node_id, &keys_manager, &secp_ctx).unwrap();
 218 ///
 219 /// // Send a custom onion message to a blinded path.
 220 /// let destination = Destination::BlindedPath(blinded_path);
 221 /// let reply_path = None;
 222 /// # let message = YourCustomMessage {};
 223 /// onion_messenger.send_onion_message(message, destination, reply_path);
 224 /// ```
 225 ///
 226 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 227 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 228 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 229 where
 230         ES::Target: EntropySource,
 231         NS::Target: NodeSigner,
 232         L::Target: Logger,
 233         NL::Target: NodeIdLookUp,
 234         MR::Target: MessageRouter,
 235         OMH::Target: OffersMessageHandler,
 236         CMH::Target: CustomOnionMessageHandler,
 237 {
 238         entropy_source: ES,
 239         node_signer: NS,
 240         logger: L,
 241         message_recipients: Mutex<HashMap<PublicKey, OnionMessageRecipient>>,
 242         secp_ctx: Secp256k1<secp256k1::All>,
 243         node_id_lookup: NL,
 244         message_router: MR,
 245         offers_handler: OMH,
 246         custom_handler: CMH,
 247         intercept_messages_for_offline_peers: bool,
 248         pending_events: Mutex<PendingEvents>,
 249 }
 250
 251 struct PendingEvents {
 252         intercepted_msgs: Vec<Event>,
 253         peer_connecteds: Vec<Event>,
 254 }
 255
 256 /// [`OnionMessage`]s buffered to be sent.
 257 enum OnionMessageRecipient {
 258         /// Messages for a node connected as a peer.
 259         ConnectedPeer(VecDeque<OnionMessage>),
 260
 261         /// Messages for a node that is not yet connected, which are dropped after [`MAX_TIMER_TICKS`]
 262         /// and tracked here.
 263         PendingConnection(VecDeque<OnionMessage>, Option<Vec<SocketAddress>>, usize),
 264 }
 265
 266 impl OnionMessageRecipient {
 267         fn pending_connection(addresses: Vec<SocketAddress>) -> Self {
 268                 Self::PendingConnection(VecDeque::new(), Some(addresses), 0)
 269         }
 270
 271         fn pending_messages(&self) -> &VecDeque<OnionMessage> {
 272                 match self {
 273                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 274                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 275                 }
 276         }
 277
 278         fn enqueue_message(&mut self, message: OnionMessage) {
 279                 let pending_messages = match self {
 280                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 281                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 282                 };
 283
 284                 pending_messages.push_back(message);
 285         }
 286
 287         fn dequeue_message(&mut self) -> Option<OnionMessage> {
 288                 let pending_messages = match self {
 289                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 290                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => {
 291                                 debug_assert!(false);
 292                                 pending_messages
 293                         },
 294                 };
 295
 296                 pending_messages.pop_front()
 297         }
 298
 299         #[cfg(test)]
 300         fn release_pending_messages(&mut self) -> VecDeque<OnionMessage> {
 301                 let pending_messages = match self {
 302                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 303                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 304                 };
 305
 306                 core::mem::take(pending_messages)
 307         }
 308
 309         fn mark_connected(&mut self) {
 310                 if let OnionMessageRecipient::PendingConnection(pending_messages, _, _) = self {
 311                         let mut new_pending_messages = VecDeque::new();
 312                         core::mem::swap(pending_messages, &mut new_pending_messages);
 313                         *self = OnionMessageRecipient::ConnectedPeer(new_pending_messages);
 314                 }
 315         }
 316
 317         fn is_connected(&self) -> bool {
 318                 match self {
 319                         OnionMessageRecipient::ConnectedPeer(..) => true,
 320                         OnionMessageRecipient::PendingConnection(..) => false,
 321                 }
 322         }
 323 }
 324
 325
 326 /// The `Responder` struct creates an appropriate [`ResponseInstruction`]
 327 /// for responding to a message.
 328 #[derive(Clone, Debug, Eq, PartialEq)]
 329 pub struct Responder {
 330         /// The path along which a response can be sent.
 331         reply_path: BlindedPath,
 332         path_id: Option<[u8; 32]>
 333 }
 334
 335 impl_writeable_tlv_based!(Responder, {
 336         (0, reply_path, required),
 337         (2, path_id, option),
 338 });
 339
 340 impl Responder {
 341         /// Creates a new [`Responder`] instance with the provided reply path.
 342         pub(super) fn new(reply_path: BlindedPath, path_id: Option<[u8; 32]>) -> Self {
 343                 Responder {
 344                         reply_path,
 345                         path_id,
 346                 }
 347         }
 348
 349         /// Creates a [`ResponseInstruction::WithoutReplyPath`] for a given response.
 350         ///
 351         /// Use when the recipient doesn't need to send back a reply to us.
 352         pub fn respond<T: OnionMessageContents>(self, response: T) -> ResponseInstruction<T> {
 353                 ResponseInstruction::WithoutReplyPath(OnionMessageResponse {
 354                         message: response,
 355                         reply_path: self.reply_path,
 356                         path_id: self.path_id,
 357                 })
 358         }
 359
 360         /// Creates a [`ResponseInstruction::WithReplyPath`] for a given response.
 361         ///
 362         /// Use when the recipient needs to send back a reply to us.
 363         pub fn respond_with_reply_path<T: OnionMessageContents>(self, response: T) -> ResponseInstruction<T> {
 364                 ResponseInstruction::WithReplyPath(OnionMessageResponse {
 365                         message: response,
 366                         reply_path: self.reply_path,
 367                         path_id: self.path_id,
 368                 })
 369         }
 370 }
 371
 372 /// This struct contains the information needed to reply to a received message.
 373 pub struct OnionMessageResponse<T: OnionMessageContents> {
 374         message: T,
 375         reply_path: BlindedPath,
 376         path_id: Option<[u8; 32]>,
 377 }
 378
 379 /// `ResponseInstruction` represents instructions for responding to received messages.
 380 pub enum ResponseInstruction<T: OnionMessageContents> {
 381         /// Indicates that a response should be sent including a reply path for
 382         /// the recipient to respond back.
 383         WithReplyPath(OnionMessageResponse<T>),
 384         /// Indicates that a response should be sent without including a reply path
 385         /// for the recipient to respond back.
 386         WithoutReplyPath(OnionMessageResponse<T>),
 387         /// Indicates that there's no response to send back.
 388         NoResponse,
 389 }
 390
 391 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 392 ///
 393 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 394 /// enqueued for sending.
 395 #[cfg(not(c_bindings))]
 396 pub struct PendingOnionMessage<T: OnionMessageContents> {
 397         /// The message contents to send in an [`OnionMessage`].
 398         pub contents: T,
 399
 400         /// The destination of the message.
 401         pub destination: Destination,
 402
 403         /// A reply path to include in the [`OnionMessage`] for a response.
 404         pub reply_path: Option<BlindedPath>,
 405 }
 406
 407 #[cfg(c_bindings)]
 408 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 409 ///
 410 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 411 /// enqueued for sending.
 412 pub type PendingOnionMessage<T> = (T, Destination, Option<BlindedPath>);
 413
 414 pub(crate) fn new_pending_onion_message<T: OnionMessageContents>(
 415         contents: T, destination: Destination, reply_path: Option<BlindedPath>
 416 ) -> PendingOnionMessage<T> {
 417         #[cfg(not(c_bindings))]
 418         return PendingOnionMessage { contents, destination, reply_path };
 419         #[cfg(c_bindings)]
 420         return (contents, destination, reply_path);
 421 }
 422
 423 /// A trait defining behavior for routing an [`OnionMessage`].
 424 pub trait MessageRouter {
 425         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 426         fn find_path(
 427                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 428         ) -> Result<OnionMessagePath, ()>;
 429
 430         /// Creates [`BlindedPath`]s to the `recipient` node. The nodes in `peers` are assumed to be
 431         /// direct peers with the `recipient`.
 432         fn create_blinded_paths<
 433                 T: secp256k1::Signing + secp256k1::Verification
 434         >(
 435                 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 436         ) -> Result<Vec<BlindedPath>, ()>;
 437
 438         /// Creates compact [`BlindedPath`]s to the `recipient` node. The nodes in `peers` are assumed
 439         /// to be direct peers with the `recipient`.
 440         ///
 441         /// Compact blinded paths use short channel ids instead of pubkeys for a smaller serialization,
 442         /// which is beneficial when a QR code is used to transport the data. The SCID is passed using a
 443         /// [`ForwardNode`] but may be `None` for graceful degradation.
 444         ///
 445         /// Implementations using additional intermediate nodes are responsible for using a
 446         /// [`ForwardNode`] with `Some` short channel id, if possible. Similarly, implementations should
 447         /// call [`BlindedPath::use_compact_introduction_node`].
 448         ///
 449         /// The provided implementation simply delegates to [`MessageRouter::create_blinded_paths`],
 450         /// ignoring the short channel ids.
 451         fn create_compact_blinded_paths<
 452                 T: secp256k1::Signing + secp256k1::Verification
 453         >(
 454                 &self, recipient: PublicKey, peers: Vec<ForwardNode>, secp_ctx: &Secp256k1<T>,
 455         ) -> Result<Vec<BlindedPath>, ()> {
 456                 let peers = peers
 457                         .into_iter()
 458                         .map(|ForwardNode { node_id, short_channel_id: _ }| node_id)
 459                         .collect();
 460                 self.create_blinded_paths(recipient, peers, secp_ctx)
 461         }
 462 }
 463
 464 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
 465 ///
 466 /// # Privacy
 467 ///
 468 /// Creating [`BlindedPath`]s may affect privacy since, if a suitable path cannot be found, it will
 469 /// create a one-hop path using the recipient as the introduction node if it is a announced node.
 470 /// Otherwise, there is no way to find a path to the introduction node in order to send a message,
 471 /// and thus an `Err` is returned.
 472 pub struct DefaultMessageRouter<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref>
 473 where
 474         L::Target: Logger,
 475         ES::Target: EntropySource,
 476 {
 477         network_graph: G,
 478         entropy_source: ES,
 479 }
 480
 481 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> DefaultMessageRouter<G, L, ES>
 482 where
 483         L::Target: Logger,
 484         ES::Target: EntropySource,
 485 {
 486         /// Creates a [`DefaultMessageRouter`] using the given [`NetworkGraph`].
 487         pub fn new(network_graph: G, entropy_source: ES) -> Self {
 488                 Self { network_graph, entropy_source }
 489         }
 490
 491         fn create_blinded_paths_from_iter<
 492                 I: Iterator<Item = ForwardNode>,
 493                 T: secp256k1::Signing + secp256k1::Verification
 494         >(
 495                 &self, recipient: PublicKey, peers: I, secp_ctx: &Secp256k1<T>, compact_paths: bool
 496         ) -> Result<Vec<BlindedPath>, ()> {
 497                 // Limit the number of blinded paths that are computed.
 498                 const MAX_PATHS: usize = 3;
 499
 500                 // Ensure peers have at least three channels so that it is more difficult to infer the
 501                 // recipient's node_id.
 502                 const MIN_PEER_CHANNELS: usize = 3;
 503
 504                 let network_graph = self.network_graph.deref().read_only();
 505                 let is_recipient_announced =
 506                         network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient));
 507
 508                 let mut peer_info = peers
 509                         // Limit to peers with announced channels
 510                         .filter_map(|peer|
 511                                 network_graph
 512                                         .node(&NodeId::from_pubkey(&peer.node_id))
 513                                         .filter(|info| info.channels.len() >= MIN_PEER_CHANNELS)
 514                                         .map(|info| (peer, info.is_tor_only(), info.channels.len()))
 515                         )
 516                         // Exclude Tor-only nodes when the recipient is announced.
 517                         .filter(|(_, is_tor_only, _)| !(*is_tor_only && is_recipient_announced))
 518                         .collect::<Vec<_>>();
 519
 520                 // Prefer using non-Tor nodes with the most channels as the introduction node.
 521                 peer_info.sort_unstable_by(|(_, a_tor_only, a_channels), (_, b_tor_only, b_channels)| {
 522                         a_tor_only.cmp(b_tor_only).then(a_channels.cmp(b_channels).reverse())
 523                 });
 524
 525                 let paths = peer_info.into_iter()
 526                         .map(|(peer, _, _)| {
 527                                 BlindedPath::new_for_message(&[peer], recipient, &*self.entropy_source, secp_ctx)
 528                         })
 529                         .take(MAX_PATHS)
 530                         .collect::<Result<Vec<_>, _>>();
 531
 532                 let mut paths = match paths {
 533                         Ok(paths) if !paths.is_empty() => Ok(paths),
 534                         _ => {
 535                                 if is_recipient_announced {
 536                                         BlindedPath::one_hop_for_message(recipient, &*self.entropy_source, secp_ctx)
 537                                                 .map(|path| vec![path])
 538                                 } else {
 539                                         Err(())
 540                                 }
 541                         },
 542                 }?;
 543
 544                 if compact_paths {
 545                         for path in &mut paths {
 546                                 path.use_compact_introduction_node(&network_graph);
 547                         }
 548                 }
 549
 550                 Ok(paths)
 551         }
 552 }
 553
 554 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> MessageRouter for DefaultMessageRouter<G, L, ES>
 555 where
 556         L::Target: Logger,
 557         ES::Target: EntropySource,
 558 {
 559         fn find_path(
 560                 &self, sender: PublicKey, peers: Vec<PublicKey>, mut destination: Destination
 561         ) -> Result<OnionMessagePath, ()> {
 562                 let network_graph = self.network_graph.deref().read_only();
 563                 destination.resolve(&network_graph);
 564
 565                 let first_node = match destination.first_node() {
 566                         Some(first_node) => first_node,
 567                         None => return Err(()),
 568                 };
 569
 570                 if peers.contains(&first_node) || sender == first_node {
 571                         Ok(OnionMessagePath {
 572                                 intermediate_nodes: vec![], destination, first_node_addresses: None
 573                         })
 574                 } else {
 575                         let node_details = network_graph
 576                                 .node(&NodeId::from_pubkey(&first_node))
 577                                 .and_then(|node_info| node_info.announcement_info.as_ref())
 578                                 .map(|announcement_info| (announcement_info.features(), announcement_info.addresses()));
 579
 580                         match node_details {
 581                                 Some((features, addresses)) if features.supports_onion_messages() && addresses.len() > 0 => {
 582                                         let first_node_addresses = Some(addresses.clone());
 583                                         Ok(OnionMessagePath {
 584                                                 intermediate_nodes: vec![], destination, first_node_addresses
 585                                         })
 586                                 },
 587                                 _ => Err(()),
 588                         }
 589                 }
 590         }
 591
 592         fn create_blinded_paths<
 593                 T: secp256k1::Signing + secp256k1::Verification
 594         >(
 595                 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 596         ) -> Result<Vec<BlindedPath>, ()> {
 597                 let peers = peers
 598                         .into_iter()
 599                         .map(|node_id| ForwardNode { node_id, short_channel_id: None });
 600                 self.create_blinded_paths_from_iter(recipient, peers, secp_ctx, false)
 601         }
 602
 603         fn create_compact_blinded_paths<
 604                 T: secp256k1::Signing + secp256k1::Verification
 605         >(
 606                 &self, recipient: PublicKey, peers: Vec<ForwardNode>, secp_ctx: &Secp256k1<T>,
 607         ) -> Result<Vec<BlindedPath>, ()> {
 608                 self.create_blinded_paths_from_iter(recipient, peers.into_iter(), secp_ctx, true)
 609         }
 610 }
 611
 612 /// A path for sending an [`OnionMessage`].
 613 #[derive(Clone)]
 614 pub struct OnionMessagePath {
 615         /// Nodes on the path between the sender and the destination.
 616         pub intermediate_nodes: Vec<PublicKey>,
 617
 618         /// The recipient of the message.
 619         pub destination: Destination,
 620
 621         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 622         ///
 623         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 624         /// this to initiate such a connection.
 625         pub first_node_addresses: Option<Vec<SocketAddress>>,
 626 }
 627
 628 impl OnionMessagePath {
 629         /// Returns the first node in the path.
 630         pub fn first_node(&self) -> Option<PublicKey> {
 631                 self.intermediate_nodes
 632                         .first()
 633                         .copied()
 634                         .or_else(|| self.destination.first_node())
 635         }
 636 }
 637
 638 /// The destination of an onion message.
 639 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 640 pub enum Destination {
 641         /// We're sending this onion message to a node.
 642         Node(PublicKey),
 643         /// We're sending this onion message to a blinded path.
 644         BlindedPath(BlindedPath),
 645 }
 646
 647 impl Destination {
 648         /// Attempts to resolve the [`IntroductionNode::DirectedShortChannelId`] of a
 649         /// [`Destination::BlindedPath`] to a [`IntroductionNode::NodeId`], if applicable, using the
 650         /// provided [`ReadOnlyNetworkGraph`].
 651         pub fn resolve(&mut self, network_graph: &ReadOnlyNetworkGraph) {
 652                 if let Destination::BlindedPath(path) = self {
 653                         if let IntroductionNode::DirectedShortChannelId(..) = path.introduction_node {
 654                                 if let Some(pubkey) = path
 655                                         .public_introduction_node_id(network_graph)
 656                                         .and_then(|node_id| node_id.as_pubkey().ok())
 657                                 {
 658                                         path.introduction_node = IntroductionNode::NodeId(pubkey);
 659                                 }
 660                         }
 661                 }
 662         }
 663
 664         pub(super) fn num_hops(&self) -> usize {
 665                 match self {
 666                         Destination::Node(_) => 1,
 667                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 668                 }
 669         }
 670
 671         fn first_node(&self) -> Option<PublicKey> {
 672                 match self {
 673                         Destination::Node(node_id) => Some(*node_id),
 674                         Destination::BlindedPath(BlindedPath { introduction_node, .. }) => {
 675                                 match introduction_node {
 676                                         IntroductionNode::NodeId(pubkey) => Some(*pubkey),
 677                                         IntroductionNode::DirectedShortChannelId(..) => None,
 678                                 }
 679                         },
 680                 }
 681         }
 682 }
 683
 684 /// Result of successfully [sending an onion message].
 685 ///
 686 /// [sending an onion message]: OnionMessenger::send_onion_message
 687 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 688 pub enum SendSuccess {
 689         /// The message was buffered and will be sent once it is processed by
 690         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 691         Buffered,
 692         /// The message was buffered and will be sent once the node is connected as a peer and it is
 693         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 694         BufferedAwaitingConnection(PublicKey),
 695 }
 696
 697 /// Errors that may occur when [sending an onion message].
 698 ///
 699 /// [sending an onion message]: OnionMessenger::send_onion_message
 700 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 701 pub enum SendError {
 702         /// Errored computing onion message packet keys.
 703         Secp256k1(secp256k1::Error),
 704         /// Because implementations such as Eclair will drop onion messages where the message packet
 705         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 706         TooBigPacket,
 707         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 708         /// hops.
 709         TooFewBlindedHops,
 710         /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
 711         InvalidFirstHop(PublicKey),
 712         /// Indicates that a path could not be found by the [`MessageRouter`].
 713         ///
 714         /// This occurs when either:
 715         /// - No path from the sender to the destination was found to send the onion message
 716         /// - No reply path to the sender could be created when responding to an onion message
 717         PathNotFound,
 718         /// Onion message contents must have a TLV type >= 64.
 719         InvalidMessage,
 720         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 721         BufferFull,
 722         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 723         ///
 724         /// [`NodeSigner`]: crate::sign::NodeSigner
 725         GetNodeIdFailed,
 726         /// The provided [`Destination`] has a blinded path with an unresolved introduction node. An
 727         /// attempt to resolve it in the [`MessageRouter`] when finding an [`OnionMessagePath`] likely
 728         /// failed.
 729         UnresolvedIntroductionNode,
 730         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 731         /// advance the blinded path to make the second hop the new introduction node. Either
 732         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 733         /// new blinding point, or we were attempting to send to ourselves.
 734         BlindedPathAdvanceFailed,
 735 }
 736
 737 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 738 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 739 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 740 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 741 /// message types.
 742 ///
 743 /// See [`OnionMessenger`] for example usage.
 744 ///
 745 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 746 /// [`CustomMessage`]: Self::CustomMessage
 747 pub trait CustomOnionMessageHandler {
 748         /// The message known to the handler. To support multiple message types, you may want to make this
 749         /// an enum with a variant for each supported message.
 750         type CustomMessage: OnionMessageContents;
 751
 752         /// Called with the custom message that was received, returning a response to send, if any.
 753         ///
 754         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 755         fn handle_custom_message(&self, message: Self::CustomMessage, responder: Option<Responder>) -> ResponseInstruction<Self::CustomMessage>;
 756
 757         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 758         /// message type is unknown.
 759         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 760
 761         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 762         ///
 763         /// Typically, this is used for messages initiating a message flow rather than in response to
 764         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 765         #[cfg(not(c_bindings))]
 766         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 767
 768         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 769         ///
 770         /// Typically, this is used for messages initiating a message flow rather than in response to
 771         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 772         #[cfg(c_bindings)]
 773         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 774 }
 775
 776 /// A processed incoming onion message, containing either a Forward (another onion message)
 777 /// or a Receive payload with decrypted contents.
 778 #[derive(Clone, Debug)]
 779 pub enum PeeledOnion<T: OnionMessageContents> {
 780         /// Forwarded onion, with the next node id and a new onion
 781         Forward(NextMessageHop, OnionMessage),
 782         /// Received onion message, with decrypted contents, path_id, and reply path
 783         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 784 }
 785
 786
 787 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 788 /// `path`, first calling [`Destination::resolve`] on `path.destination` with the given
 789 /// [`ReadOnlyNetworkGraph`].
 790 ///
 791 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 792 /// needed to connect to the first node.
 793 pub fn create_onion_message_resolving_destination<
 794         ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents
 795 >(
 796         entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
 797         network_graph: &ReadOnlyNetworkGraph, secp_ctx: &Secp256k1<secp256k1::All>,
 798         mut path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 799 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 800 where
 801         ES::Target: EntropySource,
 802         NS::Target: NodeSigner,
 803         NL::Target: NodeIdLookUp,
 804 {
 805         path.destination.resolve(network_graph);
 806         create_onion_message(
 807                 entropy_source, node_signer, node_id_lookup, secp_ctx, path, contents, reply_path,
 808         )
 809 }
 810
 811 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 812 /// `path`.
 813 ///
 814 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 815 /// needed to connect to the first node.
 816 ///
 817 /// Returns [`SendError::UnresolvedIntroductionNode`] if:
 818 /// - `destination` contains a blinded path with an [`IntroductionNode::DirectedShortChannelId`],
 819 /// - unless it can be resolved by [`NodeIdLookUp::next_node_id`].
 820 /// Use [`create_onion_message_resolving_destination`] instead to resolve the introduction node
 821 /// first with a [`ReadOnlyNetworkGraph`].
 822 pub fn create_onion_message<ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents>(
 823         entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
 824         secp_ctx: &Secp256k1<secp256k1::All>, path: OnionMessagePath, contents: T,
 825         reply_path: Option<BlindedPath>,
 826 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 827 where
 828         ES::Target: EntropySource,
 829         NS::Target: NodeSigner,
 830         NL::Target: NodeIdLookUp,
 831 {
 832         let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
 833         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 834                 if blinded_hops.is_empty() {
 835                         return Err(SendError::TooFewBlindedHops);
 836                 }
 837         }
 838
 839         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 840
 841         // If we are sending straight to a blinded path and we are the introduction node, we need to
 842         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 843         if intermediate_nodes.len() == 0 {
 844                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 845                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 846                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 847                         let introduction_node_id = match blinded_path.introduction_node {
 848                                 IntroductionNode::NodeId(pubkey) => pubkey,
 849                                 IntroductionNode::DirectedShortChannelId(direction, scid) => {
 850                                         match node_id_lookup.next_node_id(scid) {
 851                                                 Some(next_node_id) => *direction.select_pubkey(&our_node_id, &next_node_id),
 852                                                 None => return Err(SendError::UnresolvedIntroductionNode),
 853                                         }
 854                                 },
 855                         };
 856                         if introduction_node_id == our_node_id {
 857                                 advance_path_by_one(blinded_path, node_signer, node_id_lookup, &secp_ctx)
 858                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 859                         }
 860                 }
 861         }
 862
 863         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 864         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 865         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 866                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 867         } else {
 868                 match &destination {
 869                         Destination::Node(pk) => (*pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 870                         Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, .. }) => {
 871                                 match introduction_node {
 872                                         IntroductionNode::NodeId(pubkey) => (*pubkey, *blinding_point),
 873                                         IntroductionNode::DirectedShortChannelId(..) => {
 874                                                 return Err(SendError::UnresolvedIntroductionNode);
 875                                         },
 876                                 }
 877                         }
 878                 }
 879         };
 880         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 881                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret
 882         )?;
 883
 884         let prng_seed = entropy_source.get_secure_random_bytes();
 885         let onion_routing_packet = construct_onion_message_packet(
 886                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 887
 888         let message = OnionMessage { blinding_point, onion_routing_packet };
 889         Ok((first_node_id, message, first_node_addresses))
 890 }
 891
 892 /// Decode one layer of an incoming [`OnionMessage`].
 893 ///
 894 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 895 /// receiver.
 896 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 897         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 898         custom_handler: CMH,
 899 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 900 where
 901         NS::Target: NodeSigner,
 902         L::Target: Logger,
 903         CMH::Target: CustomOnionMessageHandler,
 904 {
 905         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 906                 Ok(ss) => ss,
 907                 Err(e) =>  {
 908                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 909                         return Err(());
 910                 }
 911         };
 912         let onion_decode_ss = {
 913                 let blinding_factor = {
 914                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 915                         hmac.input(control_tlvs_ss.as_ref());
 916                         Hmac::from_engine(hmac).to_byte_array()
 917                 };
 918                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 919                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 920                 {
 921                         Ok(ss) => ss.secret_bytes(),
 922                         Err(()) => {
 923                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 924                                 return Err(());
 925                         }
 926                 }
 927         };
 928         match onion_utils::decode_next_untagged_hop(
 929                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 930                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 931         ) {
 932                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 933                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 934                 }, None)) => {
 935                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 936                 },
 937                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 938                         next_hop, next_blinding_override
 939                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 940                         // TODO: we need to check whether `next_hop` is our node, in which case this is a dummy
 941                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 942                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 943                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 944                         // for now.
 945                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 946                                 Ok(pk) => pk,
 947                                 Err(e) => {
 948                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 949                                         return Err(())
 950                                 }
 951                         };
 952                         let outgoing_packet = Packet {
 953                                 version: 0,
 954                                 public_key: new_pubkey,
 955                                 hop_data: new_packet_bytes,
 956                                 hmac: next_hop_hmac,
 957                         };
 958                         let onion_message = OnionMessage {
 959                                 blinding_point: match next_blinding_override {
 960                                         Some(blinding_point) => blinding_point,
 961                                         None => {
 962                                                 match onion_utils::next_hop_pubkey(
 963                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 964                                                 ) {
 965                                                         Ok(bp) => bp,
 966                                                         Err(e) => {
 967                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 968                                                                 return Err(())
 969                                                         }
 970                                                 }
 971                                         }
 972                                 },
 973                                 onion_routing_packet: outgoing_packet,
 974                         };
 975
 976                         Ok(PeeledOnion::Forward(next_hop, onion_message))
 977                 },
 978                 Err(e) => {
 979                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 980                         Err(())
 981                 },
 982                 _ => {
 983                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 984                         Err(())
 985                 },
 986         }
 987 }
 988
 989 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 990 OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
 991 where
 992         ES::Target: EntropySource,
 993         NS::Target: NodeSigner,
 994         L::Target: Logger,
 995         NL::Target: NodeIdLookUp,
 996         MR::Target: MessageRouter,
 997         OMH::Target: OffersMessageHandler,
 998         CMH::Target: CustomOnionMessageHandler,
 999 {
1000         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
1001         /// their respective handlers.
1002         pub fn new(
1003                 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL, message_router: MR,
1004                 offers_handler: OMH, custom_handler: CMH
1005         ) -> Self {
1006                 Self::new_inner(
1007                         entropy_source, node_signer, logger, node_id_lookup, message_router,
1008                         offers_handler, custom_handler, false
1009                 )
1010         }
1011
1012         /// Similar to [`Self::new`], but rather than dropping onion messages that are
1013         /// intended to be forwarded to offline peers, we will intercept them for
1014         /// later forwarding.
1015         ///
1016         /// Interception flow:
1017         /// 1. If an onion message for an offline peer is received, `OnionMessenger` will
1018         ///    generate an [`Event::OnionMessageIntercepted`]. Event handlers can
1019         ///    then choose to persist this onion message for later forwarding, or drop
1020         ///    it.
1021         /// 2. When the offline peer later comes back online, `OnionMessenger` will
1022         ///    generate an [`Event::OnionMessagePeerConnected`]. Event handlers will
1023         ///    then fetch all previously intercepted onion messages for this peer.
1024         /// 3. Once the stored onion messages are fetched, they can finally be
1025         ///    forwarded to the now-online peer via [`Self::forward_onion_message`].
1026         ///
1027         /// # Note
1028         ///
1029         /// LDK will not rate limit how many [`Event::OnionMessageIntercepted`]s
1030         /// are generated, so it is the caller's responsibility to limit how many
1031         /// onion messages are persisted and only persist onion messages for relevant
1032         /// peers.
1033         pub fn new_with_offline_peer_interception(
1034                 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL,
1035                 message_router: MR, offers_handler: OMH, custom_handler: CMH
1036         ) -> Self {
1037                 Self::new_inner(
1038                         entropy_source, node_signer, logger, node_id_lookup, message_router,
1039                         offers_handler, custom_handler, true
1040                 )
1041         }
1042
1043         fn new_inner(
1044                 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL,
1045                 message_router: MR, offers_handler: OMH, custom_handler: CMH,
1046                 intercept_messages_for_offline_peers: bool
1047         ) -> Self {
1048                 let mut secp_ctx = Secp256k1::new();
1049                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
1050                 OnionMessenger {
1051                         entropy_source,
1052                         node_signer,
1053                         message_recipients: Mutex::new(new_hash_map()),
1054                         secp_ctx,
1055                         logger,
1056                         node_id_lookup,
1057                         message_router,
1058                         offers_handler,
1059                         custom_handler,
1060                         intercept_messages_for_offline_peers,
1061                         pending_events: Mutex::new(PendingEvents {
1062                                 intercepted_msgs: Vec::new(),
1063                                 peer_connecteds: Vec::new(),
1064                         }),
1065                 }
1066         }
1067
1068         #[cfg(test)]
1069         pub(crate) fn set_offers_handler(&mut self, offers_handler: OMH) {
1070                 self.offers_handler = offers_handler;
1071         }
1072
1073         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
1074         ///
1075         /// See [`OnionMessenger`] for example usage.
1076         pub fn send_onion_message<T: OnionMessageContents>(
1077                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
1078         ) -> Result<SendSuccess, SendError> {
1079                 self.find_path_and_enqueue_onion_message(
1080                         contents, destination, reply_path, format_args!("")
1081                 )
1082         }
1083
1084         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
1085                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
1086                 log_suffix: fmt::Arguments
1087         ) -> Result<SendSuccess, SendError> {
1088                 let mut logger = WithContext::from(&self.logger, None, None, None);
1089                 let result = self.find_path(destination).and_then(|path| {
1090                         let first_hop = path.intermediate_nodes.get(0).map(|p| *p);
1091                         logger = WithContext::from(&self.logger, first_hop, None, None);
1092                         self.enqueue_onion_message(path, contents, reply_path, log_suffix)
1093                 });
1094
1095                 match result.as_ref() {
1096                         Err(SendError::GetNodeIdFailed) => {
1097                                 log_warn!(logger, "Unable to retrieve node id {}", log_suffix);
1098                         },
1099                         Err(SendError::PathNotFound) => {
1100                                 log_trace!(logger, "Failed to find path {}", log_suffix);
1101                         },
1102                         Err(e) => {
1103                                 log_trace!(logger, "Failed sending onion message {}: {:?}", log_suffix, e);
1104                         },
1105                         Ok(SendSuccess::Buffered) => {
1106                                 log_trace!(logger, "Buffered onion message {}", log_suffix);
1107                         },
1108                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
1109                                 log_trace!(
1110                                         logger,
1111                                         "Buffered onion message waiting on peer connection {}: {}",
1112                                         log_suffix, node_id
1113                                 );
1114                         },
1115                 }
1116
1117                 result
1118         }
1119
1120         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
1121                 let sender = self.node_signer
1122                         .get_node_id(Recipient::Node)
1123                         .map_err(|_| SendError::GetNodeIdFailed)?;
1124
1125                 let peers = self.message_recipients.lock().unwrap()
1126                         .iter()
1127                         .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
1128                         .map(|(node_id, _)| *node_id)
1129                         .collect();
1130
1131                 self.message_router
1132                         .find_path(sender, peers, destination)
1133                         .map_err(|_| SendError::PathNotFound)
1134         }
1135
1136         fn create_blinded_path(&self) -> Result<BlindedPath, SendError> {
1137                 let recipient = self.node_signer
1138                         .get_node_id(Recipient::Node)
1139                         .map_err(|_| SendError::GetNodeIdFailed)?;
1140                 let secp_ctx = &self.secp_ctx;
1141
1142                 let peers = self.message_recipients.lock().unwrap()
1143                         .iter()
1144                         .filter(|(_, peer)| matches!(peer, OnionMessageRecipient::ConnectedPeer(_)))
1145                         .map(|(node_id, _ )| *node_id)
1146                         .collect::<Vec<_>>();
1147
1148                 self.message_router
1149                         .create_blinded_paths(recipient, peers, secp_ctx)
1150                         .and_then(|paths| paths.into_iter().next().ok_or(()))
1151                         .map_err(|_| SendError::PathNotFound)
1152         }
1153
1154         fn enqueue_onion_message<T: OnionMessageContents>(
1155                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
1156                 log_suffix: fmt::Arguments
1157         ) -> Result<SendSuccess, SendError> {
1158                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
1159
1160                 let (first_node_id, onion_message, addresses) = create_onion_message(
1161                         &self.entropy_source, &self.node_signer, &self.node_id_lookup, &self.secp_ctx, path,
1162                         contents, reply_path,
1163                 )?;
1164
1165                 let mut message_recipients = self.message_recipients.lock().unwrap();
1166                 if outbound_buffer_full(&first_node_id, &message_recipients) {
1167                         return Err(SendError::BufferFull);
1168                 }
1169
1170                 match message_recipients.entry(first_node_id) {
1171                         hash_map::Entry::Vacant(e) => match addresses {
1172                                 None => Err(SendError::InvalidFirstHop(first_node_id)),
1173                                 Some(addresses) => {
1174                                         e.insert(OnionMessageRecipient::pending_connection(addresses))
1175                                                 .enqueue_message(onion_message);
1176                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
1177                                 },
1178                         },
1179                         hash_map::Entry::Occupied(mut e) => {
1180                                 e.get_mut().enqueue_message(onion_message);
1181                                 if e.get().is_connected() {
1182                                         Ok(SendSuccess::Buffered)
1183                                 } else {
1184                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
1185                                 }
1186                         },
1187                 }
1188         }
1189
1190         /// Forwards an [`OnionMessage`] to `peer_node_id`. Useful if we initialized
1191         /// the [`OnionMessenger`] with [`Self::new_with_offline_peer_interception`]
1192         /// and want to forward a previously intercepted onion message to a peer that
1193         /// has just come online.
1194         pub fn forward_onion_message(
1195                 &self, message: OnionMessage, peer_node_id: &PublicKey
1196         ) -> Result<(), SendError> {
1197                 let mut message_recipients = self.message_recipients.lock().unwrap();
1198                 if outbound_buffer_full(&peer_node_id, &message_recipients) {
1199                         return Err(SendError::BufferFull);
1200                 }
1201
1202                 match message_recipients.entry(*peer_node_id) {
1203                         hash_map::Entry::Occupied(mut e) if e.get().is_connected() => {
1204                                 e.get_mut().enqueue_message(message);
1205                                 Ok(())
1206                         },
1207                         _ => Err(SendError::InvalidFirstHop(*peer_node_id))
1208                 }
1209         }
1210
1211         #[cfg(any(test, feature = "_test_utils"))]
1212         pub fn send_onion_message_using_path<T: OnionMessageContents>(
1213                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
1214         ) -> Result<SendSuccess, SendError> {
1215                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
1216         }
1217
1218         pub(crate) fn peel_onion_message(
1219                 &self, msg: &OnionMessage
1220         ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()> {
1221                 peel_onion_message(
1222                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
1223                 )
1224         }
1225
1226         /// Handles the response to an [`OnionMessage`] based on its [`ResponseInstruction`],
1227         /// enqueueing any response for sending.
1228         ///
1229         /// This function is useful for asynchronous handling of [`OnionMessage`]s.
1230         /// Handlers have the option to return [`ResponseInstruction::NoResponse`], indicating that
1231         /// no immediate response should be sent. Then, they can transfer the associated [`Responder`]
1232         /// to another task responsible for generating the response asynchronously. Subsequently, when
1233         /// the response is prepared and ready for sending, that task can invoke this method to enqueue
1234         /// the response for delivery.
1235         pub fn handle_onion_message_response<T: OnionMessageContents>(
1236                 &self, response: ResponseInstruction<T>
1237         ) -> Result<Option<SendSuccess>, SendError> {
1238                 let (response, create_reply_path) = match response {
1239                         ResponseInstruction::WithReplyPath(response) => (response, true),
1240                         ResponseInstruction::WithoutReplyPath(response) => (response, false),
1241                         ResponseInstruction::NoResponse => return Ok(None),
1242                 };
1243
1244                 let message_type = response.message.msg_type();
1245                 let reply_path = if create_reply_path {
1246                         match self.create_blinded_path() {
1247                                 Ok(reply_path) => Some(reply_path),
1248                                 Err(err) => {
1249                                         log_trace!(
1250                                                 self.logger,
1251                                                 "Failed to create reply path when responding with {} to an onion message \
1252                                                 with path_id {:02x?}: {:?}",
1253                                                 message_type, response.path_id, err
1254                                         );
1255                                         return Err(err);
1256                                 }
1257                         }
1258                 } else { None };
1259
1260                 self.find_path_and_enqueue_onion_message(
1261                         response.message, Destination::BlindedPath(response.reply_path), reply_path,
1262                         format_args!(
1263                                 "when responding with {} to an onion message with path_id {:02x?}",
1264                                 message_type,
1265                                 response.path_id
1266                         )
1267                 ).map(|result| Some(result))
1268         }
1269
1270         #[cfg(test)]
1271         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
1272                 let mut message_recipients = self.message_recipients.lock().unwrap();
1273                 let mut msgs = new_hash_map();
1274                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
1275                 // release the pending message buffers individually.
1276                 for (node_id, recipient) in &mut *message_recipients {
1277                         msgs.insert(*node_id, recipient.release_pending_messages());
1278                 }
1279                 msgs
1280         }
1281
1282         fn enqueue_intercepted_event(&self, event: Event) {
1283                 const MAX_EVENTS_BUFFER_SIZE: usize = (1 << 10) * 256;
1284                 let mut pending_events = self.pending_events.lock().unwrap();
1285                 let total_buffered_bytes: usize =
1286                         pending_events.intercepted_msgs.iter().map(|ev| ev.serialized_length()).sum();
1287                 if total_buffered_bytes >= MAX_EVENTS_BUFFER_SIZE {
1288                         log_trace!(self.logger, "Dropping event {:?}: buffer full", event);
1289                         return
1290                 }
1291                 pending_events.intercepted_msgs.push(event);
1292         }
1293
1294         /// Processes any events asynchronously using the given handler.
1295         ///
1296         /// Note that the event handler is called in the order each event was generated, however
1297         /// futures are polled in parallel for some events to allow for parallelism where events do not
1298         /// have an ordering requirement.
1299         ///
1300         /// See the trait-level documentation of [`EventsProvider`] for requirements.
1301         pub async fn process_pending_events_async<Future: core::future::Future<Output = ()> + core::marker::Unpin, H: Fn(Event) -> Future>(
1302                 &self, handler: H
1303         ) {
1304                 let mut intercepted_msgs = Vec::new();
1305                 let mut peer_connecteds = Vec::new();
1306                 {
1307                         let mut pending_events = self.pending_events.lock().unwrap();
1308                         core::mem::swap(&mut pending_events.intercepted_msgs, &mut intercepted_msgs);
1309                         core::mem::swap(&mut pending_events.peer_connecteds, &mut peer_connecteds);
1310                 }
1311
1312                 let mut futures = Vec::with_capacity(intercepted_msgs.len());
1313                 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
1314                         if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
1315                                 if let Some(addresses) = addresses.take() {
1316                                         futures.push(Some(handler(Event::ConnectionNeeded { node_id: *node_id, addresses })));
1317                                 }
1318                         }
1319                 }
1320
1321                 for ev in intercepted_msgs {
1322                         if let Event::OnionMessageIntercepted { .. } = ev {} else { debug_assert!(false); }
1323                         futures.push(Some(handler(ev)));
1324                 }
1325                 // Let the `OnionMessageIntercepted` events finish before moving on to peer_connecteds
1326                 crate::util::async_poll::MultiFuturePoller(futures).await;
1327
1328                 if peer_connecteds.len() <= 1 {
1329                         for event in peer_connecteds { handler(event).await; }
1330                 } else {
1331                         let mut futures = Vec::new();
1332                         for event in peer_connecteds {
1333                                 futures.push(Some(handler(event)));
1334                         }
1335                         crate::util::async_poll::MultiFuturePoller(futures).await;
1336                 }
1337         }
1338 }
1339
1340 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
1341         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
1342         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
1343         let mut total_buffered_bytes = 0;
1344         let mut peer_buffered_bytes = 0;
1345         for (pk, peer_buf) in buffer {
1346                 for om in peer_buf.pending_messages() {
1347                         let om_len = om.serialized_length();
1348                         if pk == peer_node_id {
1349                                 peer_buffered_bytes += om_len;
1350                         }
1351                         total_buffered_bytes += om_len;
1352
1353                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
1354                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
1355                         {
1356                                 return true
1357                         }
1358                 }
1359         }
1360         false
1361 }
1362
1363 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
1364 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
1365 where
1366         ES::Target: EntropySource,
1367         NS::Target: NodeSigner,
1368         L::Target: Logger,
1369         NL::Target: NodeIdLookUp,
1370         MR::Target: MessageRouter,
1371         OMH::Target: OffersMessageHandler,
1372         CMH::Target: CustomOnionMessageHandler,
1373 {
1374         fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
1375                 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
1376                         if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
1377                                 if let Some(addresses) = addresses.take() {
1378                                         handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
1379                                 }
1380                         }
1381                 }
1382                 let mut events = Vec::new();
1383                 {
1384                         let mut pending_events = self.pending_events.lock().unwrap();
1385                         #[cfg(debug_assertions)] {
1386                                 for ev in pending_events.intercepted_msgs.iter() {
1387                                         if let Event::OnionMessageIntercepted { .. } = ev {} else { panic!(); }
1388                                 }
1389                                 for ev in pending_events.peer_connecteds.iter() {
1390                                         if let Event::OnionMessagePeerConnected { .. } = ev {} else { panic!(); }
1391                                 }
1392                         }
1393                         core::mem::swap(&mut pending_events.intercepted_msgs, &mut events);
1394                         events.append(&mut pending_events.peer_connecteds);
1395                         pending_events.peer_connecteds.shrink_to(10); // Limit total heap usage
1396                 }
1397                 for ev in events {
1398                         handler.handle_event(ev);
1399                 }
1400         }
1401 }
1402
1403 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
1404 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
1405 where
1406         ES::Target: EntropySource,
1407         NS::Target: NodeSigner,
1408         L::Target: Logger,
1409         NL::Target: NodeIdLookUp,
1410         MR::Target: MessageRouter,
1411         OMH::Target: OffersMessageHandler,
1412         CMH::Target: CustomOnionMessageHandler,
1413 {
1414         fn handle_onion_message(&self, peer_node_id: &PublicKey, msg: &OnionMessage) {
1415                 let logger = WithContext::from(&self.logger, Some(*peer_node_id), None, None);
1416                 match self.peel_onion_message(msg) {
1417                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
1418                                 log_trace!(
1419                                         logger,
1420                                         "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
1421                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
1422
1423                                 match message {
1424                                         ParsedOnionMessageContents::Offers(msg) => {
1425                                                 let responder = reply_path.map(
1426                                                         |reply_path| Responder::new(reply_path, path_id)
1427                                                 );
1428                                                 let response_instructions = self.offers_handler.handle_message(msg, responder);
1429                                                 let _ = self.handle_onion_message_response(response_instructions);
1430                                         },
1431                                         ParsedOnionMessageContents::Custom(msg) => {
1432                                                 let responder = reply_path.map(
1433                                                         |reply_path| Responder::new(reply_path, path_id)
1434                                                 );
1435                                                 let response_instructions = self.custom_handler.handle_custom_message(msg, responder);
1436                                                 let _ = self.handle_onion_message_response(response_instructions);
1437                                         },
1438                                 }
1439                         },
1440                         Ok(PeeledOnion::Forward(next_hop, onion_message)) => {
1441                                 let next_node_id = match next_hop {
1442                                         NextMessageHop::NodeId(pubkey) => pubkey,
1443                                         NextMessageHop::ShortChannelId(scid) => match self.node_id_lookup.next_node_id(scid) {
1444                                                 Some(pubkey) => pubkey,
1445                                                 None => {
1446                                                         log_trace!(self.logger, "Dropping forwarded onion messager: unable to resolve next hop using SCID {}", scid);
1447                                                         return
1448                                                 },
1449                                         },
1450                                 };
1451
1452                                 let mut message_recipients = self.message_recipients.lock().unwrap();
1453                                 if outbound_buffer_full(&next_node_id, &message_recipients) {
1454                                         log_trace!(
1455                                                 logger,
1456                                                 "Dropping forwarded onion message to peer {}: outbound buffer full",
1457                                                 next_node_id);
1458                                         return
1459                                 }
1460
1461                                 #[cfg(fuzzing)]
1462                                 message_recipients
1463                                         .entry(next_node_id)
1464                                         .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
1465
1466                                 match message_recipients.entry(next_node_id) {
1467                                         hash_map::Entry::Occupied(mut e) if matches!(
1468                                                 e.get(), OnionMessageRecipient::ConnectedPeer(..)
1469                                         ) => {
1470                                                 e.get_mut().enqueue_message(onion_message);
1471                                                 log_trace!(logger, "Forwarding an onion message to peer {}", next_node_id);
1472                                         },
1473                                         _ if self.intercept_messages_for_offline_peers => {
1474                                                 self.enqueue_intercepted_event(
1475                                                         Event::OnionMessageIntercepted {
1476                                                                 peer_node_id: next_node_id, message: onion_message
1477                                                         }
1478                                                 );
1479                                         },
1480                                         _ => {
1481                                                 log_trace!(
1482                                                         logger,
1483                                                         "Dropping forwarded onion message to disconnected peer {}",
1484                                                         next_node_id);
1485                                                 return
1486                                         },
1487                                 }
1488                         },
1489                         Err(e) => {
1490                                 log_error!(logger, "Failed to process onion message {:?}", e);
1491                         }
1492                 }
1493         }
1494
1495         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
1496                 if init.features.supports_onion_messages() {
1497                         self.message_recipients.lock().unwrap()
1498                                 .entry(*their_node_id)
1499                                 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
1500                                 .mark_connected();
1501                         if self.intercept_messages_for_offline_peers {
1502                                 self.pending_events.lock().unwrap().peer_connecteds.push(
1503                                         Event::OnionMessagePeerConnected { peer_node_id: *their_node_id }
1504                                 );
1505                         }
1506                 } else {
1507                         self.message_recipients.lock().unwrap().remove(their_node_id);
1508                 }
1509
1510                 Ok(())
1511         }
1512
1513         fn peer_disconnected(&self, their_node_id: &PublicKey) {
1514                 match self.message_recipients.lock().unwrap().remove(their_node_id) {
1515                         Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
1516                         Some(_) => debug_assert!(false),
1517                         None => {},
1518                 }
1519         }
1520
1521         fn timer_tick_occurred(&self) {
1522                 let mut message_recipients = self.message_recipients.lock().unwrap();
1523
1524                 // Drop any pending recipients since the last call to avoid retaining buffered messages for
1525                 // too long.
1526                 message_recipients.retain(|_, recipient| match recipient {
1527                         OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
1528                         OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
1529                         _ => true,
1530                 });
1531
1532                 // Increment a timer tick for pending recipients so that their buffered messages are dropped
1533                 // at MAX_TIMER_TICKS.
1534                 for recipient in message_recipients.values_mut() {
1535                         if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
1536                                 *ticks += 1;
1537                         }
1538                 }
1539         }
1540
1541         fn provided_node_features(&self) -> NodeFeatures {
1542                 let mut features = NodeFeatures::empty();
1543                 features.set_onion_messages_optional();
1544                 features
1545         }
1546
1547         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1548                 let mut features = InitFeatures::empty();
1549                 features.set_onion_messages_optional();
1550                 features
1551         }
1552
1553         // Before returning any messages to send for the peer, this method will see if any messages were
1554         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1555         // node, and then enqueue the message for sending to the first peer in the full path.
1556         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1557                 // Enqueue any initiating `OffersMessage`s to send.
1558                 for message in self.offers_handler.release_pending_messages() {
1559                         #[cfg(not(c_bindings))]
1560                         let PendingOnionMessage { contents, destination, reply_path } = message;
1561                         #[cfg(c_bindings)]
1562                         let (contents, destination, reply_path) = message;
1563                         let _ = self.find_path_and_enqueue_onion_message(
1564                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
1565                         );
1566                 }
1567
1568                 // Enqueue any initiating `CustomMessage`s to send.
1569                 for message in self.custom_handler.release_pending_custom_messages() {
1570                         #[cfg(not(c_bindings))]
1571                         let PendingOnionMessage { contents, destination, reply_path } = message;
1572                         #[cfg(c_bindings)]
1573                         let (contents, destination, reply_path) = message;
1574                         let _ = self.find_path_and_enqueue_onion_message(
1575                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
1576                         );
1577                 }
1578
1579                 self.message_recipients.lock().unwrap()
1580                         .get_mut(&peer_node_id)
1581                         .and_then(|buffer| buffer.dequeue_message())
1582         }
1583 }
1584
1585 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1586 // produces
1587 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1588 /// [`SimpleArcPeerManager`]. See their docs for more details.
1589 ///
1590 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1591 ///
1592 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1593 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1594 #[cfg(not(c_bindings))]
1595 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1596         Arc<KeysManager>,
1597         Arc<KeysManager>,
1598         Arc<L>,
1599         Arc<SimpleArcChannelManager<M, T, F, L>>,
1600         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>, Arc<KeysManager>>>,
1601         Arc<SimpleArcChannelManager<M, T, F, L>>,
1602         IgnoringMessageHandler
1603 >;
1604
1605 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1606 /// [`SimpleRefPeerManager`]. See their docs for more details.
1607 ///
1608 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1609 ///
1610 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1611 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1612 #[cfg(not(c_bindings))]
1613 pub type SimpleRefOnionMessenger<
1614         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1615 > = OnionMessenger<
1616         &'a KeysManager,
1617         &'a KeysManager,
1618         &'b L,
1619         &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1620         &'j DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L, &'a KeysManager>,
1621         &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1622         IgnoringMessageHandler
1623 >;
1624
1625 /// Construct onion packet payloads and keys for sending an onion message along the given
1626 /// `unblinded_path` to the given `destination`.
1627 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1628         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1629         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1630 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), SendError> {
1631         let num_hops = unblinded_path.len() + destination.num_hops();
1632         let mut payloads = Vec::with_capacity(num_hops);
1633         let mut onion_packet_keys = Vec::with_capacity(num_hops);
1634
1635         let (mut intro_node_id_blinding_pt, num_blinded_hops) = match &destination {
1636                 Destination::Node(_) => (None, 0),
1637                 Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, blinded_hops }) => {
1638                         let introduction_node_id = match introduction_node {
1639                                 IntroductionNode::NodeId(pubkey) => pubkey,
1640                                 IntroductionNode::DirectedShortChannelId(..) => {
1641                                         return Err(SendError::UnresolvedIntroductionNode);
1642                                 },
1643                         };
1644                         (Some((*introduction_node_id, *blinding_point)), blinded_hops.len())
1645                 },
1646         };
1647         let num_unblinded_hops = num_hops - num_blinded_hops;
1648
1649         let mut unblinded_path_idx = 0;
1650         let mut blinded_path_idx = 0;
1651         let mut prev_control_tlvs_ss = None;
1652         let mut final_control_tlvs = None;
1653         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1654                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1655                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1656                                 if let Some(ss) = prev_control_tlvs_ss.take() {
1657                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1658                                                 ForwardTlvs {
1659                                                         next_hop: NextMessageHop::NodeId(unblinded_pk_opt.unwrap()),
1660                                                         next_blinding_override: None,
1661                                                 }
1662                                         )), ss));
1663                                 }
1664                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1665                                 unblinded_path_idx += 1;
1666                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1667                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1668                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1669                                                 next_hop: NextMessageHop::NodeId(intro_node_id),
1670                                                 next_blinding_override: Some(blinding_pt),
1671                                         })), control_tlvs_ss));
1672                                 }
1673                         }
1674                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1675                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1676                                         control_tlvs_ss));
1677                                 blinded_path_idx += 1;
1678                         } else if let Some(encrypted_payload) = enc_payload_opt {
1679                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1680                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1681                         }
1682
1683                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1684                         onion_packet_keys.push(onion_utils::OnionKeys {
1685                                 #[cfg(test)]
1686                                 shared_secret: onion_packet_ss,
1687                                 #[cfg(test)]
1688                                 blinding_factor: [0; 32],
1689                                 ephemeral_pubkey,
1690                                 rho,
1691                                 mu,
1692                         });
1693                 }
1694         ).map_err(|e| SendError::Secp256k1(e))?;
1695
1696         if let Some(control_tlvs) = final_control_tlvs {
1697                 payloads.push((Payload::Receive {
1698                         control_tlvs,
1699                         reply_path: reply_path.take(),
1700                         message,
1701                 }, prev_control_tlvs_ss.unwrap()));
1702         } else {
1703                 payloads.push((Payload::Receive {
1704                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1705                         reply_path: reply_path.take(),
1706                         message,
1707                 }, prev_control_tlvs_ss.unwrap()));
1708         }
1709
1710         Ok((payloads, onion_packet_keys))
1711 }
1712
1713 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1714 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, ()> {
1715         // Spec rationale:
1716         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1717         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1718         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1719         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1720         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1721                 SMALL_PACKET_HOP_DATA_LEN
1722         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1723                 BIG_PACKET_HOP_DATA_LEN
1724         } else { return Err(()) };
1725
1726         onion_utils::construct_onion_message_packet::<_, _>(
1727                 payloads, onion_keys, prng_seed, hop_data_len)
1728 }