_ 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;
  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 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::messenger::{Destination, MessageRouter, OnionMessagePath, OnionMessenger};
  78 /// # use lightning::onion_message::packet::OnionMessageContents;
  79 /// # use lightning::util::logger::{Logger, Record};
  80 /// # use lightning::util::ser::{Writeable, Writer};
  81 /// # use lightning::io;
  82 /// # use std::sync::Arc;
  83 /// # struct FakeLogger;
  84 /// # impl Logger for FakeLogger {
  85 /// #     fn log(&self, record: Record) { println!("{:?}" , record); }
  86 /// # }
  87 /// # struct FakeMessageRouter {}
  88 /// # impl MessageRouter for FakeMessageRouter {
  89 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  90 /// #         let secp_ctx = Secp256k1::new();
  91 /// #         let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  92 /// #         let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  93 /// #         let hop_node_id2 = hop_node_id1;
  94 /// #         Ok(OnionMessagePath {
  95 /// #             intermediate_nodes: vec![hop_node_id1, hop_node_id2],
  96 /// #             destination,
  97 /// #             first_node_addresses: None,
  98 /// #         })
  99 /// #     }
 100 /// #     fn create_blinded_paths<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
 101 /// #         &self, _recipient: PublicKey, _peers: Vec<PublicKey>, _entropy_source: &ES, _secp_ctx: &Secp256k1<T>
 102 /// #     ) -> Result<Vec<BlindedPath>, ()> {
 103 /// #         unreachable!()
 104 /// #     }
 105 /// # }
 106 /// # let seed = [42u8; 32];
 107 /// # let time = Duration::from_secs(123456);
 108 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
 109 /// # let logger = Arc::new(FakeLogger {});
 110 /// # let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
 111 /// # let secp_ctx = Secp256k1::new();
 112 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
 113 /// # let (hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1);
 114 /// # let destination_node_id = hop_node_id1;
 115 /// # let message_router = Arc::new(FakeMessageRouter {});
 116 /// # let custom_message_handler = IgnoringMessageHandler {};
 117 /// # let offers_message_handler = IgnoringMessageHandler {};
 118 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
 119 /// // ChannelManager.
 120 /// let onion_messenger = OnionMessenger::new(
 121 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
 122 ///     &custom_message_handler
 123 /// );
 124
 125 /// # #[derive(Debug)]
 126 /// # struct YourCustomMessage {}
 127 /// impl Writeable for YourCustomMessage {
 128 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 129 ///             # Ok(())
 130 ///             // Write your custom onion message to `w`
 131 ///     }
 132 /// }
 133 /// impl OnionMessageContents for YourCustomMessage {
 134 ///     fn tlv_type(&self) -> u64 {
 135 ///             # let your_custom_message_type = 42;
 136 ///             your_custom_message_type
 137 ///     }
 138 /// }
 139 /// // Send a custom onion message to a node id.
 140 /// let destination = Destination::Node(destination_node_id);
 141 /// let reply_path = None;
 142 /// # let message = YourCustomMessage {};
 143 /// onion_messenger.send_onion_message(message, destination, reply_path);
 144 ///
 145 /// // Create a blinded path to yourself, for someone to send an onion message to.
 146 /// # let your_node_id = hop_node_id1;
 147 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 148 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 149 ///
 150 /// // Send a custom onion message to a blinded path.
 151 /// let destination = Destination::BlindedPath(blinded_path);
 152 /// let reply_path = None;
 153 /// # let message = YourCustomMessage {};
 154 /// onion_messenger.send_onion_message(message, destination, reply_path);
 155 /// ```
 156 ///
 157 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 158 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 159 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 160 where
 161         ES::Target: EntropySource,
 162         NS::Target: NodeSigner,
 163         L::Target: Logger,
 164         MR::Target: MessageRouter,
 165         OMH::Target: OffersMessageHandler,
 166         CMH::Target: CustomOnionMessageHandler,
 167 {
 168         entropy_source: ES,
 169         node_signer: NS,
 170         logger: L,
 171         message_recipients: Mutex<HashMap<PublicKey, OnionMessageRecipient>>,
 172         secp_ctx: Secp256k1<secp256k1::All>,
 173         message_router: MR,
 174         offers_handler: OMH,
 175         custom_handler: CMH,
 176 }
 177
 178 /// [`OnionMessage`]s buffered to be sent.
 179 enum OnionMessageRecipient {
 180         /// Messages for a node connected as a peer.
 181         ConnectedPeer(VecDeque<OnionMessage>),
 182
 183         /// Messages for a node that is not yet connected, which are dropped after [`MAX_TIMER_TICKS`]
 184         /// and tracked here.
 185         PendingConnection(VecDeque<OnionMessage>, Option<Vec<SocketAddress>>, usize),
 186 }
 187
 188 impl OnionMessageRecipient {
 189         fn pending_connection(addresses: Vec<SocketAddress>) -> Self {
 190                 Self::PendingConnection(VecDeque::new(), Some(addresses), 0)
 191         }
 192
 193         fn pending_messages(&self) -> &VecDeque<OnionMessage> {
 194                 match self {
 195                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 196                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 197                 }
 198         }
 199
 200         fn enqueue_message(&mut self, message: OnionMessage) {
 201                 let pending_messages = match self {
 202                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 203                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 204                 };
 205
 206                 pending_messages.push_back(message);
 207         }
 208
 209         fn dequeue_message(&mut self) -> Option<OnionMessage> {
 210                 let pending_messages = match self {
 211                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 212                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => {
 213                                 debug_assert!(false);
 214                                 pending_messages
 215                         },
 216                 };
 217
 218                 pending_messages.pop_front()
 219         }
 220
 221         #[cfg(test)]
 222         fn release_pending_messages(&mut self) -> VecDeque<OnionMessage> {
 223                 let pending_messages = match self {
 224                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 225                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 226                 };
 227
 228                 core::mem::take(pending_messages)
 229         }
 230
 231         fn mark_connected(&mut self) {
 232                 if let OnionMessageRecipient::PendingConnection(pending_messages, _, _) = self {
 233                         let mut new_pending_messages = VecDeque::new();
 234                         core::mem::swap(pending_messages, &mut new_pending_messages);
 235                         *self = OnionMessageRecipient::ConnectedPeer(new_pending_messages);
 236                 }
 237         }
 238
 239         fn is_connected(&self) -> bool {
 240                 match self {
 241                         OnionMessageRecipient::ConnectedPeer(..) => true,
 242                         OnionMessageRecipient::PendingConnection(..) => false,
 243                 }
 244         }
 245 }
 246
 247 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 248 ///
 249 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 250 /// enqueued for sending.
 251 #[cfg(not(c_bindings))]
 252 pub struct PendingOnionMessage<T: OnionMessageContents> {
 253         /// The message contents to send in an [`OnionMessage`].
 254         pub contents: T,
 255
 256         /// The destination of the message.
 257         pub destination: Destination,
 258
 259         /// A reply path to include in the [`OnionMessage`] for a response.
 260         pub reply_path: Option<BlindedPath>,
 261 }
 262
 263 #[cfg(c_bindings)]
 264 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 265 ///
 266 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 267 /// enqueued for sending.
 268 pub type PendingOnionMessage<T> = (T, Destination, Option<BlindedPath>);
 269
 270 pub(crate) fn new_pending_onion_message<T: OnionMessageContents>(
 271         contents: T, destination: Destination, reply_path: Option<BlindedPath>
 272 ) -> PendingOnionMessage<T> {
 273         #[cfg(not(c_bindings))]
 274         return PendingOnionMessage { contents, destination, reply_path };
 275         #[cfg(c_bindings)]
 276         return (contents, destination, reply_path);
 277 }
 278
 279 /// A trait defining behavior for routing an [`OnionMessage`].
 280 pub trait MessageRouter {
 281         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 282         fn find_path(
 283                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 284         ) -> Result<OnionMessagePath, ()>;
 285
 286         /// Creates [`BlindedPath`]s to the `recipient` node. The nodes in `peers` are assumed to be
 287         /// direct peers with the `recipient`.
 288         fn create_blinded_paths<
 289                 ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification
 290         >(
 291                 &self, recipient: PublicKey, peers: Vec<PublicKey>, entropy_source: &ES,
 292                 secp_ctx: &Secp256k1<T>
 293         ) -> Result<Vec<BlindedPath>, ()>;
 294 }
 295
 296 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
 297 pub struct DefaultMessageRouter<G: Deref<Target=NetworkGraph<L>>, L: Deref>
 298 where
 299         L::Target: Logger,
 300 {
 301         network_graph: G,
 302 }
 303
 304 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref> DefaultMessageRouter<G, L>
 305 where
 306         L::Target: Logger,
 307 {
 308         /// Creates a [`DefaultMessageRouter`] using the given [`NetworkGraph`].
 309         pub fn new(network_graph: G) -> Self {
 310                 Self { network_graph }
 311         }
 312 }
 313
 314 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref> MessageRouter for DefaultMessageRouter<G, L>
 315 where
 316         L::Target: Logger,
 317 {
 318         fn find_path(
 319                 &self, _sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 320         ) -> Result<OnionMessagePath, ()> {
 321                 let first_node = destination.first_node();
 322                 if peers.contains(&first_node) {
 323                         Ok(OnionMessagePath {
 324                                 intermediate_nodes: vec![], destination, first_node_addresses: None
 325                         })
 326                 } else {
 327                         let network_graph = self.network_graph.deref().read_only();
 328                         let node_announcement = network_graph
 329                                 .node(&NodeId::from_pubkey(&first_node))
 330                                 .and_then(|node_info| node_info.announcement_info.as_ref())
 331                                 .and_then(|announcement_info| announcement_info.announcement_message.as_ref())
 332                                 .map(|node_announcement| &node_announcement.contents);
 333
 334                         match node_announcement {
 335                                 Some(node_announcement) if node_announcement.features.supports_onion_messages() => {
 336                                         let first_node_addresses = Some(node_announcement.addresses.clone());
 337                                         Ok(OnionMessagePath {
 338                                                 intermediate_nodes: vec![], destination, first_node_addresses
 339                                         })
 340                                 },
 341                                 _ => Err(()),
 342                         }
 343                 }
 344         }
 345
 346         fn create_blinded_paths<
 347                 ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification
 348         >(
 349                 &self, recipient: PublicKey, peers: Vec<PublicKey>, entropy_source: &ES,
 350                 secp_ctx: &Secp256k1<T>
 351         ) -> Result<Vec<BlindedPath>, ()> {
 352                 // Limit the number of blinded paths that are computed.
 353                 const MAX_PATHS: usize = 3;
 354
 355                 // Ensure peers have at least three channels so that it is more difficult to infer the
 356                 // recipient's node_id.
 357                 const MIN_PEER_CHANNELS: usize = 3;
 358
 359                 let network_graph = self.network_graph.deref().read_only();
 360                 let paths = peers.iter()
 361                         // Limit to peers with announced channels
 362                         .filter(|pubkey|
 363                                 network_graph
 364                                         .node(&NodeId::from_pubkey(pubkey))
 365                                         .map(|info| &info.channels[..])
 366                                         .map(|channels| channels.len() >= MIN_PEER_CHANNELS)
 367                                         .unwrap_or(false)
 368                         )
 369                         .map(|pubkey| vec![*pubkey, recipient])
 370                         .map(|node_pks| BlindedPath::new_for_message(&node_pks, entropy_source, secp_ctx))
 371                         .take(MAX_PATHS)
 372                         .collect::<Result<Vec<_>, _>>();
 373
 374                 match paths {
 375                         Ok(paths) if !paths.is_empty() => Ok(paths),
 376                         _ => {
 377                                 if network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient)) {
 378                                         BlindedPath::one_hop_for_message(recipient, entropy_source, secp_ctx)
 379                                                 .map(|path| vec![path])
 380                                 } else {
 381                                         Err(())
 382                                 }
 383                         },
 384                 }
 385         }
 386 }
 387
 388 /// A path for sending an [`OnionMessage`].
 389 #[derive(Clone)]
 390 pub struct OnionMessagePath {
 391         /// Nodes on the path between the sender and the destination.
 392         pub intermediate_nodes: Vec<PublicKey>,
 393
 394         /// The recipient of the message.
 395         pub destination: Destination,
 396
 397         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 398         ///
 399         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 400         /// this to initiate such a connection.
 401         pub first_node_addresses: Option<Vec<SocketAddress>>,
 402 }
 403
 404 impl OnionMessagePath {
 405         /// Returns the first node in the path.
 406         pub fn first_node(&self) -> PublicKey {
 407                 self.intermediate_nodes
 408                         .first()
 409                         .copied()
 410                         .unwrap_or_else(|| self.destination.first_node())
 411         }
 412 }
 413
 414 /// The destination of an onion message.
 415 #[derive(Clone)]
 416 pub enum Destination {
 417         /// We're sending this onion message to a node.
 418         Node(PublicKey),
 419         /// We're sending this onion message to a blinded path.
 420         BlindedPath(BlindedPath),
 421 }
 422
 423 impl Destination {
 424         pub(super) fn num_hops(&self) -> usize {
 425                 match self {
 426                         Destination::Node(_) => 1,
 427                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 428                 }
 429         }
 430
 431         fn first_node(&self) -> PublicKey {
 432                 match self {
 433                         Destination::Node(node_id) => *node_id,
 434                         Destination::BlindedPath(BlindedPath { introduction_node_id: node_id, .. }) => *node_id,
 435                 }
 436         }
 437 }
 438
 439 /// Result of successfully [sending an onion message].
 440 ///
 441 /// [sending an onion message]: OnionMessenger::send_onion_message
 442 #[derive(Debug, PartialEq, Eq)]
 443 pub enum SendSuccess {
 444         /// The message was buffered and will be sent once it is processed by
 445         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 446         Buffered,
 447         /// The message was buffered and will be sent once the node is connected as a peer and it is
 448         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 449         BufferedAwaitingConnection(PublicKey),
 450 }
 451
 452 /// Errors that may occur when [sending an onion message].
 453 ///
 454 /// [sending an onion message]: OnionMessenger::send_onion_message
 455 #[derive(Debug, PartialEq, Eq)]
 456 pub enum SendError {
 457         /// Errored computing onion message packet keys.
 458         Secp256k1(secp256k1::Error),
 459         /// Because implementations such as Eclair will drop onion messages where the message packet
 460         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 461         TooBigPacket,
 462         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 463         /// hops.
 464         TooFewBlindedHops,
 465         /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
 466         InvalidFirstHop(PublicKey),
 467         /// A path from the sender to the destination could not be found by the [`MessageRouter`].
 468         PathNotFound,
 469         /// Onion message contents must have a TLV type >= 64.
 470         InvalidMessage,
 471         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 472         BufferFull,
 473         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 474         ///
 475         /// [`NodeSigner`]: crate::sign::NodeSigner
 476         GetNodeIdFailed,
 477         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 478         /// advance the blinded path to make the second hop the new introduction node. Either
 479         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 480         /// new blinding point, or we were attempting to send to ourselves.
 481         BlindedPathAdvanceFailed,
 482 }
 483
 484 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 485 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 486 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 487 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 488 /// message types.
 489 ///
 490 /// See [`OnionMessenger`] for example usage.
 491 ///
 492 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 493 /// [`CustomMessage`]: Self::CustomMessage
 494 pub trait CustomOnionMessageHandler {
 495         /// The message known to the handler. To support multiple message types, you may want to make this
 496         /// an enum with a variant for each supported message.
 497         type CustomMessage: OnionMessageContents;
 498
 499         /// Called with the custom message that was received, returning a response to send, if any.
 500         ///
 501         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 502         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 503
 504         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 505         /// message type is unknown.
 506         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 507
 508         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 509         ///
 510         /// Typically, this is used for messages initiating a message flow rather than in response to
 511         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 512         #[cfg(not(c_bindings))]
 513         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 514
 515         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 516         ///
 517         /// Typically, this is used for messages initiating a message flow rather than in response to
 518         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 519         #[cfg(c_bindings)]
 520         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 521 }
 522
 523 /// A processed incoming onion message, containing either a Forward (another onion message)
 524 /// or a Receive payload with decrypted contents.
 525 pub enum PeeledOnion<T: OnionMessageContents> {
 526         /// Forwarded onion, with the next node id and a new onion
 527         Forward(PublicKey, OnionMessage),
 528         /// Received onion message, with decrypted contents, path_id, and reply path
 529         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 530 }
 531
 532 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 533 /// `path`.
 534 ///
 535 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 536 /// need to connect to the first node.
 537 pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
 538         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 539         path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 540 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 541 where
 542         ES::Target: EntropySource,
 543         NS::Target: NodeSigner,
 544 {
 545         let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
 546         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 547                 if blinded_hops.is_empty() {
 548                         return Err(SendError::TooFewBlindedHops);
 549                 }
 550         }
 551
 552         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 553
 554         // If we are sending straight to a blinded path and we are the introduction node, we need to
 555         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 556         if intermediate_nodes.len() == 0 {
 557                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 558                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 559                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 560                         if blinded_path.introduction_node_id == our_node_id {
 561                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 562                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 563                         }
 564                 }
 565         }
 566
 567         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 568         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 569         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 570                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 571         } else {
 572                 match destination {
 573                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 574                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 575                                 (introduction_node_id, blinding_point),
 576                 }
 577         };
 578         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 579                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret)
 580                 .map_err(|e| SendError::Secp256k1(e))?;
 581
 582         let prng_seed = entropy_source.get_secure_random_bytes();
 583         let onion_routing_packet = construct_onion_message_packet(
 584                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 585
 586         let message = OnionMessage { blinding_point, onion_routing_packet };
 587         Ok((first_node_id, message, first_node_addresses))
 588 }
 589
 590 /// Decode one layer of an incoming [`OnionMessage`].
 591 ///
 592 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 593 /// receiver.
 594 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 595         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 596         custom_handler: CMH,
 597 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 598 where
 599         NS::Target: NodeSigner,
 600         L::Target: Logger,
 601         CMH::Target: CustomOnionMessageHandler,
 602 {
 603         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 604                 Ok(ss) => ss,
 605                 Err(e) =>  {
 606                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 607                         return Err(());
 608                 }
 609         };
 610         let onion_decode_ss = {
 611                 let blinding_factor = {
 612                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 613                         hmac.input(control_tlvs_ss.as_ref());
 614                         Hmac::from_engine(hmac).to_byte_array()
 615                 };
 616                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 617                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 618                 {
 619                         Ok(ss) => ss.secret_bytes(),
 620                         Err(()) => {
 621                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 622                                 return Err(());
 623                         }
 624                 }
 625         };
 626         match onion_utils::decode_next_untagged_hop(
 627                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 628                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 629         ) {
 630                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 631                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 632                 }, None)) => {
 633                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 634                 },
 635                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 636                         next_node_id, next_blinding_override
 637                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 638                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 639                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 640                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 641                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 642                         // for now.
 643                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 644                                 Ok(pk) => pk,
 645                                 Err(e) => {
 646                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 647                                         return Err(())
 648                                 }
 649                         };
 650                         let outgoing_packet = Packet {
 651                                 version: 0,
 652                                 public_key: new_pubkey,
 653                                 hop_data: new_packet_bytes,
 654                                 hmac: next_hop_hmac,
 655                         };
 656                         let onion_message = OnionMessage {
 657                                 blinding_point: match next_blinding_override {
 658                                         Some(blinding_point) => blinding_point,
 659                                         None => {
 660                                                 match onion_utils::next_hop_pubkey(
 661                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 662                                                 ) {
 663                                                         Ok(bp) => bp,
 664                                                         Err(e) => {
 665                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 666                                                                 return Err(())
 667                                                         }
 668                                                 }
 669                                         }
 670                                 },
 671                                 onion_routing_packet: outgoing_packet,
 672                         };
 673
 674                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 675                 },
 676                 Err(e) => {
 677                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 678                         Err(())
 679                 },
 680                 _ => {
 681                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 682                         Err(())
 683                 },
 684         }
 685 }
 686
 687 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 688 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 689 where
 690         ES::Target: EntropySource,
 691         NS::Target: NodeSigner,
 692         L::Target: Logger,
 693         MR::Target: MessageRouter,
 694         OMH::Target: OffersMessageHandler,
 695         CMH::Target: CustomOnionMessageHandler,
 696 {
 697         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 698         /// their respective handlers.
 699         pub fn new(
 700                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 701                 custom_handler: CMH
 702         ) -> Self {
 703                 let mut secp_ctx = Secp256k1::new();
 704                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 705                 OnionMessenger {
 706                         entropy_source,
 707                         node_signer,
 708                         message_recipients: Mutex::new(HashMap::new()),
 709                         secp_ctx,
 710                         logger,
 711                         message_router,
 712                         offers_handler,
 713                         custom_handler,
 714                 }
 715         }
 716
 717         #[cfg(test)]
 718         pub(crate) fn set_offers_handler(&mut self, offers_handler: OMH) {
 719                 self.offers_handler = offers_handler;
 720         }
 721
 722         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
 723         ///
 724         /// See [`OnionMessenger`] for example usage.
 725         pub fn send_onion_message<T: OnionMessageContents>(
 726                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
 727         ) -> Result<SendSuccess, SendError> {
 728                 self.find_path_and_enqueue_onion_message(
 729                         contents, destination, reply_path, format_args!("")
 730                 )
 731         }
 732
 733         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 734                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 735                 log_suffix: fmt::Arguments
 736         ) -> Result<SendSuccess, SendError> {
 737                 let result = self.find_path(destination)
 738                         .and_then(|path| self.enqueue_onion_message(path, contents, reply_path, log_suffix));
 739
 740                 match result.as_ref() {
 741                         Err(SendError::GetNodeIdFailed) => {
 742                                 log_warn!(self.logger, "Unable to retrieve node id {}", log_suffix);
 743                         },
 744                         Err(SendError::PathNotFound) => {
 745                                 log_trace!(self.logger, "Failed to find path {}", log_suffix);
 746                         },
 747                         Err(e) => {
 748                                 log_trace!(self.logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 749                         },
 750                         Ok(SendSuccess::Buffered) => {
 751                                 log_trace!(self.logger, "Buffered onion message {}", log_suffix);
 752                         },
 753                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
 754                                 log_trace!(
 755                                         self.logger, "Buffered onion message waiting on peer connection {}: {:?}",
 756                                         log_suffix, node_id
 757                                 );
 758                         },
 759                 }
 760
 761                 result
 762         }
 763
 764         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
 765                 let sender = self.node_signer
 766                         .get_node_id(Recipient::Node)
 767                         .map_err(|_| SendError::GetNodeIdFailed)?;
 768
 769                 let peers = self.message_recipients.lock().unwrap()
 770                         .iter()
 771                         .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
 772                         .map(|(node_id, _)| *node_id)
 773                         .collect();
 774
 775                 self.message_router
 776                         .find_path(sender, peers, destination)
 777                         .map_err(|_| SendError::PathNotFound)
 778         }
 779
 780         fn enqueue_onion_message<T: OnionMessageContents>(
 781                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 782                 log_suffix: fmt::Arguments
 783         ) -> Result<SendSuccess, SendError> {
 784                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 785
 786                 let (first_node_id, onion_message, addresses) = create_onion_message(
 787                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
 788                 )?;
 789
 790                 let mut message_recipients = self.message_recipients.lock().unwrap();
 791                 if outbound_buffer_full(&first_node_id, &message_recipients) {
 792                         return Err(SendError::BufferFull);
 793                 }
 794
 795                 match message_recipients.entry(first_node_id) {
 796                         hash_map::Entry::Vacant(e) => match addresses {
 797                                 None => Err(SendError::InvalidFirstHop(first_node_id)),
 798                                 Some(addresses) => {
 799                                         e.insert(OnionMessageRecipient::pending_connection(addresses))
 800                                                 .enqueue_message(onion_message);
 801                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 802                                 },
 803                         },
 804                         hash_map::Entry::Occupied(mut e) => {
 805                                 e.get_mut().enqueue_message(onion_message);
 806                                 if e.get().is_connected() {
 807                                         Ok(SendSuccess::Buffered)
 808                                 } else {
 809                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 810                                 }
 811                         },
 812                 }
 813         }
 814
 815         #[cfg(test)]
 816         pub(super) fn send_onion_message_using_path<T: OnionMessageContents>(
 817                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
 818         ) -> Result<SendSuccess, SendError> {
 819                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
 820         }
 821
 822         pub(crate) fn peel_onion_message(
 823                 &self, msg: &OnionMessage
 824         ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()> {
 825                 peel_onion_message(
 826                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
 827                 )
 828         }
 829
 830         fn handle_onion_message_response<T: OnionMessageContents>(
 831                 &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
 832         ) {
 833                 if let Some(response) = response {
 834                         match reply_path {
 835                                 Some(reply_path) => {
 836                                         let _ = self.find_path_and_enqueue_onion_message(
 837                                                 response, Destination::BlindedPath(reply_path), None, log_suffix
 838                                         );
 839                                 },
 840                                 None => {
 841                                         log_trace!(self.logger, "Missing reply path {}", log_suffix);
 842                                 },
 843                         }
 844                 }
 845         }
 846
 847         #[cfg(test)]
 848         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 849                 let mut message_recipients = self.message_recipients.lock().unwrap();
 850                 let mut msgs = HashMap::new();
 851                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 852                 // release the pending message buffers individually.
 853                 for (node_id, recipient) in &mut *message_recipients {
 854                         msgs.insert(*node_id, recipient.release_pending_messages());
 855                 }
 856                 msgs
 857         }
 858 }
 859
 860 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
 861         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 862         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 863         let mut total_buffered_bytes = 0;
 864         let mut peer_buffered_bytes = 0;
 865         for (pk, peer_buf) in buffer {
 866                 for om in peer_buf.pending_messages() {
 867                         let om_len = om.serialized_length();
 868                         if pk == peer_node_id {
 869                                 peer_buffered_bytes += om_len;
 870                         }
 871                         total_buffered_bytes += om_len;
 872
 873                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 874                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 875                         {
 876                                 return true
 877                         }
 878                 }
 879         }
 880         false
 881 }
 882
 883 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
 884 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 885 where
 886         ES::Target: EntropySource,
 887         NS::Target: NodeSigner,
 888         L::Target: Logger,
 889         MR::Target: MessageRouter,
 890         OMH::Target: OffersMessageHandler,
 891         CMH::Target: CustomOnionMessageHandler,
 892 {
 893         fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
 894                 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
 895                         if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
 896                                 if let Some(addresses) = addresses.take() {
 897                                         handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
 898                                 }
 899                         }
 900                 }
 901         }
 902 }
 903
 904 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 905 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 906 where
 907         ES::Target: EntropySource,
 908         NS::Target: NodeSigner,
 909         L::Target: Logger,
 910         MR::Target: MessageRouter,
 911         OMH::Target: OffersMessageHandler,
 912         CMH::Target: CustomOnionMessageHandler,
 913 {
 914         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
 915                 match self.peel_onion_message(msg) {
 916                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 917                                 log_trace!(
 918                                         self.logger,
 919                                    "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
 920                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
 921
 922                                 match message {
 923                                         ParsedOnionMessageContents::Offers(msg) => {
 924                                                 let response = self.offers_handler.handle_message(msg);
 925                                                 self.handle_onion_message_response(
 926                                                         response, reply_path, format_args!(
 927                                                                 "when responding to Offers onion message with path_id {:02x?}",
 928                                                                 path_id
 929                                                         )
 930                                                 );
 931                                         },
 932                                         ParsedOnionMessageContents::Custom(msg) => {
 933                                                 let response = self.custom_handler.handle_custom_message(msg);
 934                                                 self.handle_onion_message_response(
 935                                                         response, reply_path, format_args!(
 936                                                                 "when responding to Custom onion message with path_id {:02x?}",
 937                                                                 path_id
 938                                                         )
 939                                                 );
 940                                         },
 941                                 }
 942                         },
 943                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 944                                 let mut message_recipients = self.message_recipients.lock().unwrap();
 945                                 if outbound_buffer_full(&next_node_id, &message_recipients) {
 946                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 947                                         return
 948                                 }
 949
 950                                 #[cfg(fuzzing)]
 951                                 message_recipients
 952                                         .entry(next_node_id)
 953                                         .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
 954
 955                                 match message_recipients.entry(next_node_id) {
 956                                         hash_map::Entry::Occupied(mut e) if matches!(
 957                                                 e.get(), OnionMessageRecipient::ConnectedPeer(..)
 958                                         ) => {
 959                                                 e.get_mut().enqueue_message(onion_message);
 960                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 961                                         },
 962                                         _ => {
 963                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 964                                                 return
 965                                         },
 966                                 }
 967                         },
 968                         Err(e) => {
 969                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
 970                         }
 971                 }
 972         }
 973
 974         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 975                 if init.features.supports_onion_messages() {
 976                         self.message_recipients.lock().unwrap()
 977                                 .entry(*their_node_id)
 978                                 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
 979                                 .mark_connected();
 980                 } else {
 981                         self.message_recipients.lock().unwrap().remove(their_node_id);
 982                 }
 983
 984                 Ok(())
 985         }
 986
 987         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 988                 match self.message_recipients.lock().unwrap().remove(their_node_id) {
 989                         Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
 990                         Some(_) => debug_assert!(false),
 991                         None => {},
 992                 }
 993         }
 994
 995         fn timer_tick_occurred(&self) {
 996                 let mut message_recipients = self.message_recipients.lock().unwrap();
 997
 998                 // Drop any pending recipients since the last call to avoid retaining buffered messages for
 999                 // too long.
1000                 message_recipients.retain(|_, recipient| match recipient {
1001                         OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
1002                         OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
1003                         _ => true,
1004                 });
1005
1006                 // Increment a timer tick for pending recipients so that their buffered messages are dropped
1007                 // at MAX_TIMER_TICKS.
1008                 for recipient in message_recipients.values_mut() {
1009                         if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
1010                                 *ticks += 1;
1011                         }
1012                 }
1013         }
1014
1015         fn provided_node_features(&self) -> NodeFeatures {
1016                 let mut features = NodeFeatures::empty();
1017                 features.set_onion_messages_optional();
1018                 features
1019         }
1020
1021         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1022                 let mut features = InitFeatures::empty();
1023                 features.set_onion_messages_optional();
1024                 features
1025         }
1026
1027         // Before returning any messages to send for the peer, this method will see if any messages were
1028         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1029         // node, and then enqueue the message for sending to the first peer in the full path.
1030         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1031                 // Enqueue any initiating `OffersMessage`s to send.
1032                 for message in self.offers_handler.release_pending_messages() {
1033                         #[cfg(not(c_bindings))]
1034                         let PendingOnionMessage { contents, destination, reply_path } = message;
1035                         #[cfg(c_bindings)]
1036                         let (contents, destination, reply_path) = message;
1037                         let _ = self.find_path_and_enqueue_onion_message(
1038                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
1039                         );
1040                 }
1041
1042                 // Enqueue any initiating `CustomMessage`s to send.
1043                 for message in self.custom_handler.release_pending_custom_messages() {
1044                         #[cfg(not(c_bindings))]
1045                         let PendingOnionMessage { contents, destination, reply_path } = message;
1046                         #[cfg(c_bindings)]
1047                         let (contents, destination, reply_path) = message;
1048                         let _ = self.find_path_and_enqueue_onion_message(
1049                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
1050                         );
1051                 }
1052
1053                 self.message_recipients.lock().unwrap()
1054                         .get_mut(&peer_node_id)
1055                         .and_then(|buffer| buffer.dequeue_message())
1056         }
1057 }
1058
1059 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1060 // produces
1061 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1062 /// [`SimpleArcPeerManager`]. See their docs for more details.
1063 ///
1064 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1065 ///
1066 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1067 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1068 #[cfg(not(c_bindings))]
1069 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1070         Arc<KeysManager>,
1071         Arc<KeysManager>,
1072         Arc<L>,
1073         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>>>,
1074         Arc<SimpleArcChannelManager<M, T, F, L>>,
1075         IgnoringMessageHandler
1076 >;
1077
1078 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1079 /// [`SimpleRefPeerManager`]. See their docs for more details.
1080 ///
1081 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1082 ///
1083 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1084 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1085 #[cfg(not(c_bindings))]
1086 pub type SimpleRefOnionMessenger<
1087         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1088 > = OnionMessenger<
1089         &'a KeysManager,
1090         &'a KeysManager,
1091         &'b L,
1092         &'i DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L>,
1093         &'j SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1094         IgnoringMessageHandler
1095 >;
1096
1097 /// Construct onion packet payloads and keys for sending an onion message along the given
1098 /// `unblinded_path` to the given `destination`.
1099 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1100         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1101         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1102 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
1103         let num_hops = unblinded_path.len() + destination.num_hops();
1104         let mut payloads = Vec::with_capacity(num_hops);
1105         let mut onion_packet_keys = Vec::with_capacity(num_hops);
1106
1107         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
1108                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
1109                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
1110         let num_unblinded_hops = num_hops - num_blinded_hops;
1111
1112         let mut unblinded_path_idx = 0;
1113         let mut blinded_path_idx = 0;
1114         let mut prev_control_tlvs_ss = None;
1115         let mut final_control_tlvs = None;
1116         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1117                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1118                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1119                                 if let Some(ss) = prev_control_tlvs_ss.take() {
1120                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1121                                                 ForwardTlvs {
1122                                                         next_node_id: unblinded_pk_opt.unwrap(),
1123                                                         next_blinding_override: None,
1124                                                 }
1125                                         )), ss));
1126                                 }
1127                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1128                                 unblinded_path_idx += 1;
1129                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1130                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1131                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1132                                                 next_node_id: intro_node_id,
1133                                                 next_blinding_override: Some(blinding_pt),
1134                                         })), control_tlvs_ss));
1135                                 }
1136                         }
1137                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1138                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1139                                         control_tlvs_ss));
1140                                 blinded_path_idx += 1;
1141                         } else if let Some(encrypted_payload) = enc_payload_opt {
1142                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1143                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1144                         }
1145
1146                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1147                         onion_packet_keys.push(onion_utils::OnionKeys {
1148                                 #[cfg(test)]
1149                                 shared_secret: onion_packet_ss,
1150                                 #[cfg(test)]
1151                                 blinding_factor: [0; 32],
1152                                 ephemeral_pubkey,
1153                                 rho,
1154                                 mu,
1155                         });
1156                 }
1157         )?;
1158
1159         if let Some(control_tlvs) = final_control_tlvs {
1160                 payloads.push((Payload::Receive {
1161                         control_tlvs,
1162                         reply_path: reply_path.take(),
1163                         message,
1164                 }, prev_control_tlvs_ss.unwrap()));
1165         } else {
1166                 payloads.push((Payload::Receive {
1167                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1168                         reply_path: reply_path.take(),
1169                         message,
1170                 }, prev_control_tlvs_ss.unwrap()));
1171         }
1172
1173         Ok((payloads, onion_packet_keys))
1174 }
1175
1176 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1177 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, ()> {
1178         // Spec rationale:
1179         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1180         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1181         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1182         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1183         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1184                 SMALL_PACKET_HOP_DATA_LEN
1185         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1186                 BIG_PACKET_HOP_DATA_LEN
1187         } else { return Err(()) };
1188
1189         onion_utils::construct_onion_message_packet::<_, _>(
1190                 payloads, onion_keys, prng_seed, hop_data_len)
1191 }