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