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