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