_ 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 the [`OnionMessenger`]. See its docs for
  11 //! more information.
  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;
  19 use crate::blinded_path::message::{advance_path_by_one, ForwardTlvs, ReceiveTlvs};
  20 use crate::blinded_path::utils;
  21 use crate::events::{Event, EventHandler, EventsProvider};
  22 use crate::sign::{EntropySource, NodeSigner, Recipient};
  23 #[cfg(not(c_bindings))]
  24 use crate::ln::channelmanager::{SimpleArcChannelManager, SimpleRefChannelManager};
  25 use crate::ln::features::{InitFeatures, NodeFeatures};
  26 use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler, SocketAddress};
  27 use crate::ln::onion_utils;
  28 use crate::routing::gossip::{NetworkGraph, NodeId};
  29 pub use super::packet::OnionMessageContents;
  30 use super::packet::ParsedOnionMessageContents;
  31 use super::offers::OffersMessageHandler;
  32 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  33 use crate::util::logger::Logger;
  34 use crate::util::ser::Writeable;
  35
  36 use core::fmt;
  37 use core::ops::Deref;
  38 use crate::io;
  39 use crate::sync::Mutex;
  40 use crate::prelude::*;
  41
  42 #[cfg(not(c_bindings))]
  43 use {
  44         crate::sign::KeysManager,
  45         crate::ln::peer_handler::IgnoringMessageHandler,
  46         crate::sync::Arc,
  47 };
  48
  49 pub(super) const MAX_TIMER_TICKS: usize = 2;
  50
  51 /// A sender, receiver and forwarder of [`OnionMessage`]s.
  52 ///
  53 /// # Handling Messages
  54 ///
  55 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
  56 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
  57 /// available handlers are:
  58 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
  59 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
  60 ///
  61 /// # Sending Messages
  62 ///
  63 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
  64 /// a message, the matched handler may return a response message which `OnionMessenger` will send
  65 /// on its behalf.
  66 ///
  67 /// # Example
  68 ///
  69 /// ```
  70 /// # extern crate bitcoin;
  71 /// # use bitcoin::hashes::_export::_core::time::Duration;
  72 /// # use bitcoin::hashes::hex::FromHex;
  73 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey, self};
  74 /// # use lightning::blinded_path::BlindedPath;
  75 /// # use lightning::sign::{EntropySource, KeysManager};
  76 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  77 /// # use lightning::onion_message::{OnionMessageContents, Destination, MessageRouter, OnionMessagePath, OnionMessenger};
  78 /// # use lightning::util::logger::{Logger, Record};
  79 /// # use lightning::util::ser::{Writeable, Writer};
  80 /// # use lightning::io;
  81 /// # use std::sync::Arc;
  82 /// # struct FakeLogger;
  83 /// # impl Logger for FakeLogger {
  84 /// #     fn log(&self, record: Record) { println!("{:?}" , record); }
  85 /// # }
  86 /// # struct FakeMessageRouter {}
  87 /// # impl MessageRouter for FakeMessageRouter {
  88 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  89 /// #         let secp_ctx = Secp256k1::new();
  90 /// #         let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  91 /// #         let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  92 /// #         let hop_node_id2 = hop_node_id1;
  93 /// #         Ok(OnionMessagePath {
  94 /// #             intermediate_nodes: vec![hop_node_id1, hop_node_id2],
  95 /// #             destination,
  96 /// #             first_node_addresses: None,
  97 /// #         })
  98 /// #     }
  99 /// #     fn create_blinded_paths<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
 100 /// #         &self, _recipient: PublicKey, _peers: Vec<PublicKey>, _entropy_source: &ES, _secp_ctx: &Secp256k1<T>
 101 /// #     ) -> Result<Vec<BlindedPath>, ()> {
 102 /// #         unreachable!()
 103 /// #     }
 104 /// # }
 105 /// # let seed = [42u8; 32];
 106 /// # let time = Duration::from_secs(123456);
 107 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
 108 /// # let logger = Arc::new(FakeLogger {});
 109 /// # let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
 110 /// # let secp_ctx = Secp256k1::new();
 111 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
 112 /// # let (hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1);
 113 /// # let destination_node_id = hop_node_id1;
 114 /// # let message_router = Arc::new(FakeMessageRouter {});
 115 /// # let custom_message_handler = IgnoringMessageHandler {};
 116 /// # let offers_message_handler = IgnoringMessageHandler {};
 117 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
 118 /// // ChannelManager.
 119 /// let onion_messenger = OnionMessenger::new(
 120 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
 121 ///     &custom_message_handler
 122 /// );
 123
 124 /// # #[derive(Debug)]
 125 /// # struct YourCustomMessage {}
 126 /// impl Writeable for YourCustomMessage {
 127 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 128 ///             # Ok(())
 129 ///             // Write your custom onion message to `w`
 130 ///     }
 131 /// }
 132 /// impl OnionMessageContents for YourCustomMessage {
 133 ///     fn tlv_type(&self) -> u64 {
 134 ///             # let your_custom_message_type = 42;
 135 ///             your_custom_message_type
 136 ///     }
 137 /// }
 138 /// // Send a custom onion message to a node id.
 139 /// let destination = Destination::Node(destination_node_id);
 140 /// let reply_path = None;
 141 /// # let message = YourCustomMessage {};
 142 /// onion_messenger.send_onion_message(message, destination, reply_path);
 143 ///
 144 /// // Create a blinded path to yourself, for someone to send an onion message to.
 145 /// # let your_node_id = hop_node_id1;
 146 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 147 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 148 ///
 149 /// // Send a custom onion message to a blinded path.
 150 /// let destination = Destination::BlindedPath(blinded_path);
 151 /// let reply_path = None;
 152 /// # let message = YourCustomMessage {};
 153 /// onion_messenger.send_onion_message(message, destination, reply_path);
 154 /// ```
 155 ///
 156 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 157 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 158 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 159 where
 160         ES::Target: EntropySource,
 161         NS::Target: NodeSigner,
 162         L::Target: Logger,
 163         MR::Target: MessageRouter,
 164         OMH::Target: OffersMessageHandler,
 165         CMH::Target: CustomOnionMessageHandler,
 166 {
 167         entropy_source: ES,
 168         node_signer: NS,
 169         logger: L,
 170         message_recipients: Mutex<HashMap<PublicKey, OnionMessageRecipient>>,
 171         secp_ctx: Secp256k1<secp256k1::All>,
 172         message_router: MR,
 173         offers_handler: OMH,
 174         custom_handler: CMH,
 175 }
 176
 177 /// [`OnionMessage`]s buffered to be sent.
 178 enum OnionMessageRecipient {
 179         /// Messages for a node connected as a peer.
 180         ConnectedPeer(VecDeque<OnionMessage>),
 181
 182         /// Messages for a node that is not yet connected, which are dropped after [`MAX_TIMER_TICKS`]
 183         /// and tracked here.
 184         PendingConnection(VecDeque<OnionMessage>, Option<Vec<SocketAddress>>, usize),
 185 }
 186
 187 impl OnionMessageRecipient {
 188         fn pending_connection(addresses: Vec<SocketAddress>) -> Self {
 189                 Self::PendingConnection(VecDeque::new(), Some(addresses), 0)
 190         }
 191
 192         fn pending_messages(&self) -> &VecDeque<OnionMessage> {
 193                 match self {
 194                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 195                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 196                 }
 197         }
 198
 199         fn enqueue_message(&mut self, message: OnionMessage) {
 200                 let pending_messages = match self {
 201                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 202                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 203                 };
 204
 205                 pending_messages.push_back(message);
 206         }
 207
 208         fn dequeue_message(&mut self) -> Option<OnionMessage> {
 209                 let pending_messages = match self {
 210                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 211                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => {
 212                                 debug_assert!(false);
 213                                 pending_messages
 214                         },
 215                 };
 216
 217                 pending_messages.pop_front()
 218         }
 219
 220         #[cfg(test)]
 221         fn release_pending_messages(&mut self) -> VecDeque<OnionMessage> {
 222                 let pending_messages = match self {
 223                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 224                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 225                 };
 226
 227                 core::mem::take(pending_messages)
 228         }
 229
 230         fn mark_connected(&mut self) {
 231                 if let OnionMessageRecipient::PendingConnection(pending_messages, _, _) = self {
 232                         let mut new_pending_messages = VecDeque::new();
 233                         core::mem::swap(pending_messages, &mut new_pending_messages);
 234                         *self = OnionMessageRecipient::ConnectedPeer(new_pending_messages);
 235                 }
 236         }
 237
 238         fn is_connected(&self) -> bool {
 239                 match self {
 240                         OnionMessageRecipient::ConnectedPeer(..) => true,
 241                         OnionMessageRecipient::PendingConnection(..) => false,
 242                 }
 243         }
 244 }
 245
 246 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 247 ///
 248 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 249 /// enqueued for sending.
 250 #[cfg(not(c_bindings))]
 251 pub struct PendingOnionMessage<T: OnionMessageContents> {
 252         /// The message contents to send in an [`OnionMessage`].
 253         pub contents: T,
 254
 255         /// The destination of the message.
 256         pub destination: Destination,
 257
 258         /// A reply path to include in the [`OnionMessage`] for a response.
 259         pub reply_path: Option<BlindedPath>,
 260 }
 261
 262 #[cfg(c_bindings)]
 263 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 264 ///
 265 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 266 /// enqueued for sending.
 267 pub type PendingOnionMessage<T> = (T, Destination, Option<BlindedPath>);
 268
 269 pub(crate) fn new_pending_onion_message<T: OnionMessageContents>(
 270         contents: T, destination: Destination, reply_path: Option<BlindedPath>
 271 ) -> PendingOnionMessage<T> {
 272         #[cfg(not(c_bindings))]
 273         return PendingOnionMessage { contents, destination, reply_path };
 274         #[cfg(c_bindings)]
 275         return (contents, destination, reply_path);
 276 }
 277
 278 /// A trait defining behavior for routing an [`OnionMessage`].
 279 pub trait MessageRouter {
 280         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 281         fn find_path(
 282                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 283         ) -> Result<OnionMessagePath, ()>;
 284
 285         /// Creates [`BlindedPath`]s to the `recipient` node. The nodes in `peers` are assumed to be
 286         /// direct peers with the `recipient`.
 287         fn create_blinded_paths<
 288                 ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification
 289         >(
 290                 &self, recipient: PublicKey, peers: Vec<PublicKey>, entropy_source: &ES,
 291                 secp_ctx: &Secp256k1<T>
 292         ) -> Result<Vec<BlindedPath>, ()>;
 293 }
 294
 295 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
 296 pub struct DefaultMessageRouter<G: Deref<Target=NetworkGraph<L>>, L: Deref>
 297 where
 298         L::Target: Logger,
 299 {
 300         network_graph: G,
 301 }
 302
 303 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref> DefaultMessageRouter<G, L>
 304 where
 305         L::Target: Logger,
 306 {
 307         /// Creates a [`DefaultMessageRouter`] using the given [`NetworkGraph`].
 308         pub fn new(network_graph: G) -> Self {
 309                 Self { network_graph }
 310         }
 311 }
 312
 313 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref> MessageRouter for DefaultMessageRouter<G, L>
 314 where
 315         L::Target: Logger,
 316 {
 317         fn find_path(
 318                 &self, _sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 319         ) -> Result<OnionMessagePath, ()> {
 320                 let first_node = destination.first_node();
 321                 if peers.contains(&first_node) {
 322                         Ok(OnionMessagePath {
 323                                 intermediate_nodes: vec![], destination, first_node_addresses: None
 324                         })
 325                 } else {
 326                         let network_graph = self.network_graph.deref().read_only();
 327                         let node_announcement = network_graph
 328                                 .node(&NodeId::from_pubkey(&first_node))
 329                                 .and_then(|node_info| node_info.announcement_info.as_ref())
 330                                 .and_then(|announcement_info| announcement_info.announcement_message.as_ref())
 331                                 .map(|node_announcement| &node_announcement.contents);
 332
 333                         match node_announcement {
 334                                 Some(node_announcement) if node_announcement.features.supports_onion_messages() => {
 335                                         let first_node_addresses = Some(node_announcement.addresses.clone());
 336                                         Ok(OnionMessagePath {
 337                                                 intermediate_nodes: vec![], destination, first_node_addresses
 338                                         })
 339                                 },
 340                                 _ => Err(()),
 341                         }
 342                 }
 343         }
 344
 345         fn create_blinded_paths<
 346                 ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification
 347         >(
 348                 &self, recipient: PublicKey, peers: Vec<PublicKey>, entropy_source: &ES,
 349                 secp_ctx: &Secp256k1<T>
 350         ) -> Result<Vec<BlindedPath>, ()> {
 351                 // Limit the number of blinded paths that are computed.
 352                 const MAX_PATHS: usize = 3;
 353
 354                 // Ensure peers have at least three channels so that it is more difficult to infer the
 355                 // recipient's node_id.
 356                 const MIN_PEER_CHANNELS: usize = 3;
 357
 358                 let network_graph = self.network_graph.deref().read_only();
 359                 let paths = peers.iter()
 360                         // Limit to peers with announced channels
 361                         .filter(|pubkey|
 362                                 network_graph
 363                                         .node(&NodeId::from_pubkey(pubkey))
 364                                         .map(|info| &info.channels[..])
 365                                         .map(|channels| channels.len() >= MIN_PEER_CHANNELS)
 366                                         .unwrap_or(false)
 367                         )
 368                         .map(|pubkey| vec![*pubkey, recipient])
 369                         .map(|node_pks| BlindedPath::new_for_message(&node_pks, entropy_source, secp_ctx))
 370                         .take(MAX_PATHS)
 371                         .collect::<Result<Vec<_>, _>>();
 372
 373                 match paths {
 374                         Ok(paths) if !paths.is_empty() => Ok(paths),
 375                         _ => {
 376                                 if network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient)) {
 377                                         BlindedPath::one_hop_for_message(recipient, entropy_source, secp_ctx)
 378                                                 .map(|path| vec![path])
 379                                 } else {
 380                                         Err(())
 381                                 }
 382                         },
 383                 }
 384         }
 385 }
 386
 387 /// A path for sending an [`OnionMessage`].
 388 #[derive(Clone)]
 389 pub struct OnionMessagePath {
 390         /// Nodes on the path between the sender and the destination.
 391         pub intermediate_nodes: Vec<PublicKey>,
 392
 393         /// The recipient of the message.
 394         pub destination: Destination,
 395
 396         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 397         ///
 398         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 399         /// this to initiate such a connection.
 400         pub first_node_addresses: Option<Vec<SocketAddress>>,
 401 }
 402
 403 impl OnionMessagePath {
 404         /// Returns the first node in the path.
 405         pub fn first_node(&self) -> PublicKey {
 406                 self.intermediate_nodes
 407                         .first()
 408                         .copied()
 409                         .unwrap_or_else(|| self.destination.first_node())
 410         }
 411 }
 412
 413 /// The destination of an onion message.
 414 #[derive(Clone)]
 415 pub enum Destination {
 416         /// We're sending this onion message to a node.
 417         Node(PublicKey),
 418         /// We're sending this onion message to a blinded path.
 419         BlindedPath(BlindedPath),
 420 }
 421
 422 impl Destination {
 423         pub(super) fn num_hops(&self) -> usize {
 424                 match self {
 425                         Destination::Node(_) => 1,
 426                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 427                 }
 428         }
 429
 430         fn first_node(&self) -> PublicKey {
 431                 match self {
 432                         Destination::Node(node_id) => *node_id,
 433                         Destination::BlindedPath(BlindedPath { introduction_node_id: node_id, .. }) => *node_id,
 434                 }
 435         }
 436 }
 437
 438 /// Result of successfully [sending an onion message].
 439 ///
 440 /// [sending an onion message]: OnionMessenger::send_onion_message
 441 #[derive(Debug, PartialEq, Eq)]
 442 pub enum SendSuccess {
 443         /// The message was buffered and will be sent once it is processed by
 444         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 445         Buffered,
 446         /// The message was buffered and will be sent once the node is connected as a peer and it is
 447         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 448         BufferedAwaitingConnection(PublicKey),
 449 }
 450
 451 /// Errors that may occur when [sending an onion message].
 452 ///
 453 /// [sending an onion message]: OnionMessenger::send_onion_message
 454 #[derive(Debug, PartialEq, Eq)]
 455 pub enum SendError {
 456         /// Errored computing onion message packet keys.
 457         Secp256k1(secp256k1::Error),
 458         /// Because implementations such as Eclair will drop onion messages where the message packet
 459         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 460         TooBigPacket,
 461         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 462         /// hops.
 463         TooFewBlindedHops,
 464         /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
 465         InvalidFirstHop(PublicKey),
 466         /// A path from the sender to the destination could not be found by the [`MessageRouter`].
 467         PathNotFound,
 468         /// Onion message contents must have a TLV type >= 64.
 469         InvalidMessage,
 470         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 471         BufferFull,
 472         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 473         ///
 474         /// [`NodeSigner`]: crate::sign::NodeSigner
 475         GetNodeIdFailed,
 476         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 477         /// advance the blinded path to make the second hop the new introduction node. Either
 478         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 479         /// new blinding point, or we were attempting to send to ourselves.
 480         BlindedPathAdvanceFailed,
 481 }
 482
 483 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 484 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 485 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 486 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 487 /// message types.
 488 ///
 489 /// See [`OnionMessenger`] for example usage.
 490 ///
 491 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 492 /// [`CustomMessage`]: Self::CustomMessage
 493 pub trait CustomOnionMessageHandler {
 494         /// The message known to the handler. To support multiple message types, you may want to make this
 495         /// an enum with a variant for each supported message.
 496         type CustomMessage: OnionMessageContents;
 497
 498         /// Called with the custom message that was received, returning a response to send, if any.
 499         ///
 500         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 501         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 502
 503         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 504         /// message type is unknown.
 505         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 506
 507         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 508         ///
 509         /// Typically, this is used for messages initiating a message flow rather than in response to
 510         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 511         #[cfg(not(c_bindings))]
 512         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 513
 514         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 515         ///
 516         /// Typically, this is used for messages initiating a message flow rather than in response to
 517         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 518         #[cfg(c_bindings)]
 519         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 520 }
 521
 522 /// A processed incoming onion message, containing either a Forward (another onion message)
 523 /// or a Receive payload with decrypted contents.
 524 pub enum PeeledOnion<T: OnionMessageContents> {
 525         /// Forwarded onion, with the next node id and a new onion
 526         Forward(PublicKey, OnionMessage),
 527         /// Received onion message, with decrypted contents, path_id, and reply path
 528         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 529 }
 530
 531 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 532 /// `path`.
 533 ///
 534 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 535 /// need to connect to the first node.
 536 pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
 537         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 538         path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 539 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 540 where
 541         ES::Target: EntropySource,
 542         NS::Target: NodeSigner,
 543 {
 544         let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
 545         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 546                 if blinded_hops.is_empty() {
 547                         return Err(SendError::TooFewBlindedHops);
 548                 }
 549         }
 550
 551         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 552
 553         // If we are sending straight to a blinded path and we are the introduction node, we need to
 554         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 555         if intermediate_nodes.len() == 0 {
 556                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 557                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 558                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 559                         if blinded_path.introduction_node_id == our_node_id {
 560                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 561                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 562                         }
 563                 }
 564         }
 565
 566         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 567         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 568         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 569                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 570         } else {
 571                 match destination {
 572                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 573                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 574                                 (introduction_node_id, blinding_point),
 575                 }
 576         };
 577         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 578                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret)
 579                 .map_err(|e| SendError::Secp256k1(e))?;
 580
 581         let prng_seed = entropy_source.get_secure_random_bytes();
 582         let onion_routing_packet = construct_onion_message_packet(
 583                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 584
 585         let message = OnionMessage { blinding_point, onion_routing_packet };
 586         Ok((first_node_id, message, first_node_addresses))
 587 }
 588
 589 /// Decode one layer of an incoming [`OnionMessage`].
 590 ///
 591 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 592 /// receiver.
 593 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 594         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 595         custom_handler: CMH,
 596 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 597 where
 598         NS::Target: NodeSigner,
 599         L::Target: Logger,
 600         CMH::Target: CustomOnionMessageHandler,
 601 {
 602         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 603                 Ok(ss) => ss,
 604                 Err(e) =>  {
 605                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 606                         return Err(());
 607                 }
 608         };
 609         let onion_decode_ss = {
 610                 let blinding_factor = {
 611                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 612                         hmac.input(control_tlvs_ss.as_ref());
 613                         Hmac::from_engine(hmac).to_byte_array()
 614                 };
 615                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 616                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 617                 {
 618                         Ok(ss) => ss.secret_bytes(),
 619                         Err(()) => {
 620                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 621                                 return Err(());
 622                         }
 623                 }
 624         };
 625         match onion_utils::decode_next_untagged_hop(
 626                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 627                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 628         ) {
 629                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 630                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 631                 }, None)) => {
 632                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 633                 },
 634                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 635                         next_node_id, next_blinding_override
 636                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 637                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 638                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 639                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 640                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 641                         // for now.
 642                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 643                                 Ok(pk) => pk,
 644                                 Err(e) => {
 645                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 646                                         return Err(())
 647                                 }
 648                         };
 649                         let outgoing_packet = Packet {
 650                                 version: 0,
 651                                 public_key: new_pubkey,
 652                                 hop_data: new_packet_bytes,
 653                                 hmac: next_hop_hmac,
 654                         };
 655                         let onion_message = OnionMessage {
 656                                 blinding_point: match next_blinding_override {
 657                                         Some(blinding_point) => blinding_point,
 658                                         None => {
 659                                                 match onion_utils::next_hop_pubkey(
 660                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 661                                                 ) {
 662                                                         Ok(bp) => bp,
 663                                                         Err(e) => {
 664                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 665                                                                 return Err(())
 666                                                         }
 667                                                 }
 668                                         }
 669                                 },
 670                                 onion_routing_packet: outgoing_packet,
 671                         };
 672
 673                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 674                 },
 675                 Err(e) => {
 676                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 677                         Err(())
 678                 },
 679                 _ => {
 680                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 681                         Err(())
 682                 },
 683         }
 684 }
 685
 686 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 687 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 688 where
 689         ES::Target: EntropySource,
 690         NS::Target: NodeSigner,
 691         L::Target: Logger,
 692         MR::Target: MessageRouter,
 693         OMH::Target: OffersMessageHandler,
 694         CMH::Target: CustomOnionMessageHandler,
 695 {
 696         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 697         /// their respective handlers.
 698         pub fn new(
 699                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 700                 custom_handler: CMH
 701         ) -> Self {
 702                 let mut secp_ctx = Secp256k1::new();
 703                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 704                 OnionMessenger {
 705                         entropy_source,
 706                         node_signer,
 707                         message_recipients: Mutex::new(HashMap::new()),
 708                         secp_ctx,
 709                         logger,
 710                         message_router,
 711                         offers_handler,
 712                         custom_handler,
 713                 }
 714         }
 715
 716         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
 717         ///
 718         /// See [`OnionMessenger`] for example usage.
 719         pub fn send_onion_message<T: OnionMessageContents>(
 720                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
 721         ) -> Result<SendSuccess, SendError> {
 722                 self.find_path_and_enqueue_onion_message(
 723                         contents, destination, reply_path, format_args!("")
 724                 )
 725         }
 726
 727         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 728                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 729                 log_suffix: fmt::Arguments
 730         ) -> Result<SendSuccess, SendError> {
 731                 let result = self.find_path(destination)
 732                         .and_then(|path| self.enqueue_onion_message(path, contents, reply_path, log_suffix));
 733
 734                 match result.as_ref() {
 735                         Err(SendError::GetNodeIdFailed) => {
 736                                 log_warn!(self.logger, "Unable to retrieve node id {}", log_suffix);
 737                         },
 738                         Err(SendError::PathNotFound) => {
 739                                 log_trace!(self.logger, "Failed to find path {}", log_suffix);
 740                         },
 741                         Err(e) => {
 742                                 log_trace!(self.logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 743                         },
 744                         Ok(SendSuccess::Buffered) => {
 745                                 log_trace!(self.logger, "Buffered onion message {}", log_suffix);
 746                         },
 747                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
 748                                 log_trace!(
 749                                         self.logger, "Buffered onion message waiting on peer connection {}: {:?}",
 750                                         log_suffix, node_id
 751                                 );
 752                         },
 753                 }
 754
 755                 result
 756         }
 757
 758         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
 759                 let sender = self.node_signer
 760                         .get_node_id(Recipient::Node)
 761                         .map_err(|_| SendError::GetNodeIdFailed)?;
 762
 763                 let peers = self.message_recipients.lock().unwrap()
 764                         .iter()
 765                         .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
 766                         .map(|(node_id, _)| *node_id)
 767                         .collect();
 768
 769                 self.message_router
 770                         .find_path(sender, peers, destination)
 771                         .map_err(|_| SendError::PathNotFound)
 772         }
 773
 774         fn enqueue_onion_message<T: OnionMessageContents>(
 775                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 776                 log_suffix: fmt::Arguments
 777         ) -> Result<SendSuccess, SendError> {
 778                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 779
 780                 let (first_node_id, onion_message, addresses) = create_onion_message(
 781                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
 782                 )?;
 783
 784                 let mut message_recipients = self.message_recipients.lock().unwrap();
 785                 if outbound_buffer_full(&first_node_id, &message_recipients) {
 786                         return Err(SendError::BufferFull);
 787                 }
 788
 789                 match message_recipients.entry(first_node_id) {
 790                         hash_map::Entry::Vacant(e) => match addresses {
 791                                 None => Err(SendError::InvalidFirstHop(first_node_id)),
 792                                 Some(addresses) => {
 793                                         e.insert(OnionMessageRecipient::pending_connection(addresses))
 794                                                 .enqueue_message(onion_message);
 795                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 796                                 },
 797                         },
 798                         hash_map::Entry::Occupied(mut e) => {
 799                                 e.get_mut().enqueue_message(onion_message);
 800                                 if e.get().is_connected() {
 801                                         Ok(SendSuccess::Buffered)
 802                                 } else {
 803                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 804                                 }
 805                         },
 806                 }
 807         }
 808
 809         #[cfg(test)]
 810         pub(super) fn send_onion_message_using_path<T: OnionMessageContents>(
 811                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
 812         ) -> Result<SendSuccess, SendError> {
 813                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
 814         }
 815
 816         fn handle_onion_message_response<T: OnionMessageContents>(
 817                 &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
 818         ) {
 819                 if let Some(response) = response {
 820                         match reply_path {
 821                                 Some(reply_path) => {
 822                                         let _ = self.find_path_and_enqueue_onion_message(
 823                                                 response, Destination::BlindedPath(reply_path), None, log_suffix
 824                                         );
 825                                 },
 826                                 None => {
 827                                         log_trace!(self.logger, "Missing reply path {}", log_suffix);
 828                                 },
 829                         }
 830                 }
 831         }
 832
 833         #[cfg(test)]
 834         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 835                 let mut message_recipients = self.message_recipients.lock().unwrap();
 836                 let mut msgs = HashMap::new();
 837                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 838                 // release the pending message buffers individually.
 839                 for (node_id, recipient) in &mut *message_recipients {
 840                         msgs.insert(*node_id, recipient.release_pending_messages());
 841                 }
 842                 msgs
 843         }
 844 }
 845
 846 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
 847         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 848         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 849         let mut total_buffered_bytes = 0;
 850         let mut peer_buffered_bytes = 0;
 851         for (pk, peer_buf) in buffer {
 852                 for om in peer_buf.pending_messages() {
 853                         let om_len = om.serialized_length();
 854                         if pk == peer_node_id {
 855                                 peer_buffered_bytes += om_len;
 856                         }
 857                         total_buffered_bytes += om_len;
 858
 859                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 860                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 861                         {
 862                                 return true
 863                         }
 864                 }
 865         }
 866         false
 867 }
 868
 869 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
 870 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 871 where
 872         ES::Target: EntropySource,
 873         NS::Target: NodeSigner,
 874         L::Target: Logger,
 875         MR::Target: MessageRouter,
 876         OMH::Target: OffersMessageHandler,
 877         CMH::Target: CustomOnionMessageHandler,
 878 {
 879         fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
 880                 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
 881                         if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
 882                                 if let Some(addresses) = addresses.take() {
 883                                         handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
 884                                 }
 885                         }
 886                 }
 887         }
 888 }
 889
 890 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 891 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 892 where
 893         ES::Target: EntropySource,
 894         NS::Target: NodeSigner,
 895         L::Target: Logger,
 896         MR::Target: MessageRouter,
 897         OMH::Target: OffersMessageHandler,
 898         CMH::Target: CustomOnionMessageHandler,
 899 {
 900         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
 901                 match peel_onion_message(
 902                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
 903                 ) {
 904                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 905                                 log_trace!(
 906                                         self.logger,
 907                                    "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
 908                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
 909
 910                                 match message {
 911                                         ParsedOnionMessageContents::Offers(msg) => {
 912                                                 let response = self.offers_handler.handle_message(msg);
 913                                                 self.handle_onion_message_response(
 914                                                         response, reply_path, format_args!(
 915                                                                 "when responding to Offers onion message with path_id {:02x?}",
 916                                                                 path_id
 917                                                         )
 918                                                 );
 919                                         },
 920                                         ParsedOnionMessageContents::Custom(msg) => {
 921                                                 let response = self.custom_handler.handle_custom_message(msg);
 922                                                 self.handle_onion_message_response(
 923                                                         response, reply_path, format_args!(
 924                                                                 "when responding to Custom onion message with path_id {:02x?}",
 925                                                                 path_id
 926                                                         )
 927                                                 );
 928                                         },
 929                                 }
 930                         },
 931                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 932                                 let mut message_recipients = self.message_recipients.lock().unwrap();
 933                                 if outbound_buffer_full(&next_node_id, &message_recipients) {
 934                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 935                                         return
 936                                 }
 937
 938                                 #[cfg(fuzzing)]
 939                                 message_recipients
 940                                         .entry(next_node_id)
 941                                         .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
 942
 943                                 match message_recipients.entry(next_node_id) {
 944                                         hash_map::Entry::Occupied(mut e) if matches!(
 945                                                 e.get(), OnionMessageRecipient::ConnectedPeer(..)
 946                                         ) => {
 947                                                 e.get_mut().enqueue_message(onion_message);
 948                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 949                                         },
 950                                         _ => {
 951                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 952                                                 return
 953                                         },
 954                                 }
 955                         },
 956                         Err(e) => {
 957                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
 958                         }
 959                 }
 960         }
 961
 962         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 963                 if init.features.supports_onion_messages() {
 964                         self.message_recipients.lock().unwrap()
 965                                 .entry(*their_node_id)
 966                                 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
 967                                 .mark_connected();
 968                 } else {
 969                         self.message_recipients.lock().unwrap().remove(their_node_id);
 970                 }
 971
 972                 Ok(())
 973         }
 974
 975         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 976                 match self.message_recipients.lock().unwrap().remove(their_node_id) {
 977                         Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
 978                         Some(_) => debug_assert!(false),
 979                         None => {},
 980                 }
 981         }
 982
 983         fn timer_tick_occurred(&self) {
 984                 let mut message_recipients = self.message_recipients.lock().unwrap();
 985
 986                 // Drop any pending recipients since the last call to avoid retaining buffered messages for
 987                 // too long.
 988                 message_recipients.retain(|_, recipient| match recipient {
 989                         OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
 990                         OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
 991                         _ => true,
 992                 });
 993
 994                 // Increment a timer tick for pending recipients so that their buffered messages are dropped
 995                 // at MAX_TIMER_TICKS.
 996                 for recipient in message_recipients.values_mut() {
 997                         if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
 998                                 *ticks += 1;
 999                         }
1000                 }
1001         }
1002
1003         fn provided_node_features(&self) -> NodeFeatures {
1004                 let mut features = NodeFeatures::empty();
1005                 features.set_onion_messages_optional();
1006                 features
1007         }
1008
1009         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1010                 let mut features = InitFeatures::empty();
1011                 features.set_onion_messages_optional();
1012                 features
1013         }
1014
1015         // Before returning any messages to send for the peer, this method will see if any messages were
1016         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1017         // node, and then enqueue the message for sending to the first peer in the full path.
1018         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1019                 // Enqueue any initiating `OffersMessage`s to send.
1020                 for message in self.offers_handler.release_pending_messages() {
1021                         #[cfg(not(c_bindings))]
1022                         let PendingOnionMessage { contents, destination, reply_path } = message;
1023                         #[cfg(c_bindings)]
1024                         let (contents, destination, reply_path) = message;
1025                         let _ = self.find_path_and_enqueue_onion_message(
1026                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
1027                         );
1028                 }
1029
1030                 // Enqueue any initiating `CustomMessage`s to send.
1031                 for message in self.custom_handler.release_pending_custom_messages() {
1032                         #[cfg(not(c_bindings))]
1033                         let PendingOnionMessage { contents, destination, reply_path } = message;
1034                         #[cfg(c_bindings)]
1035                         let (contents, destination, reply_path) = message;
1036                         let _ = self.find_path_and_enqueue_onion_message(
1037                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
1038                         );
1039                 }
1040
1041                 self.message_recipients.lock().unwrap()
1042                         .get_mut(&peer_node_id)
1043                         .and_then(|buffer| buffer.dequeue_message())
1044         }
1045 }
1046
1047 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1048 // produces
1049 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1050 /// [`SimpleArcPeerManager`]. See their docs for more details.
1051 ///
1052 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1053 ///
1054 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1055 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1056 #[cfg(not(c_bindings))]
1057 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1058         Arc<KeysManager>,
1059         Arc<KeysManager>,
1060         Arc<L>,
1061         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>>>,
1062         Arc<SimpleArcChannelManager<M, T, F, L>>,
1063         IgnoringMessageHandler
1064 >;
1065
1066 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1067 /// [`SimpleRefPeerManager`]. See their docs for more details.
1068 ///
1069 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1070 ///
1071 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1072 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1073 #[cfg(not(c_bindings))]
1074 pub type SimpleRefOnionMessenger<
1075         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1076 > = OnionMessenger<
1077         &'a KeysManager,
1078         &'a KeysManager,
1079         &'b L,
1080         &'i DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L>,
1081         &'j SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1082         IgnoringMessageHandler
1083 >;
1084
1085 /// Construct onion packet payloads and keys for sending an onion message along the given
1086 /// `unblinded_path` to the given `destination`.
1087 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1088         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1089         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1090 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
1091         let num_hops = unblinded_path.len() + destination.num_hops();
1092         let mut payloads = Vec::with_capacity(num_hops);
1093         let mut onion_packet_keys = Vec::with_capacity(num_hops);
1094
1095         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
1096                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
1097                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
1098         let num_unblinded_hops = num_hops - num_blinded_hops;
1099
1100         let mut unblinded_path_idx = 0;
1101         let mut blinded_path_idx = 0;
1102         let mut prev_control_tlvs_ss = None;
1103         let mut final_control_tlvs = None;
1104         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1105                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1106                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1107                                 if let Some(ss) = prev_control_tlvs_ss.take() {
1108                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1109                                                 ForwardTlvs {
1110                                                         next_node_id: unblinded_pk_opt.unwrap(),
1111                                                         next_blinding_override: None,
1112                                                 }
1113                                         )), ss));
1114                                 }
1115                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1116                                 unblinded_path_idx += 1;
1117                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1118                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1119                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1120                                                 next_node_id: intro_node_id,
1121                                                 next_blinding_override: Some(blinding_pt),
1122                                         })), control_tlvs_ss));
1123                                 }
1124                         }
1125                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1126                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1127                                         control_tlvs_ss));
1128                                 blinded_path_idx += 1;
1129                         } else if let Some(encrypted_payload) = enc_payload_opt {
1130                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1131                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1132                         }
1133
1134                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1135                         onion_packet_keys.push(onion_utils::OnionKeys {
1136                                 #[cfg(test)]
1137                                 shared_secret: onion_packet_ss,
1138                                 #[cfg(test)]
1139                                 blinding_factor: [0; 32],
1140                                 ephemeral_pubkey,
1141                                 rho,
1142                                 mu,
1143                         });
1144                 }
1145         )?;
1146
1147         if let Some(control_tlvs) = final_control_tlvs {
1148                 payloads.push((Payload::Receive {
1149                         control_tlvs,
1150                         reply_path: reply_path.take(),
1151                         message,
1152                 }, prev_control_tlvs_ss.unwrap()));
1153         } else {
1154                 payloads.push((Payload::Receive {
1155                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1156                         reply_path: reply_path.take(),
1157                         message,
1158                 }, prev_control_tlvs_ss.unwrap()));
1159         }
1160
1161         Ok((payloads, onion_packet_keys))
1162 }
1163
1164 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1165 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, ()> {
1166         // Spec rationale:
1167         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1168         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1169         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1170         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1171         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1172                 SMALL_PACKET_HOP_DATA_LEN
1173         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1174                 BIG_PACKET_HOP_DATA_LEN
1175         } else { return Err(()) };
1176
1177         onion_utils::construct_onion_message_packet::<_, _>(
1178                 payloads, onion_keys, prng_seed, hop_data_len)
1179 }