_ 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, Clone)]
 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> DefaultMessageRouter<G, L, ES>
 317 where
 318         L::Target: Logger,
 319         ES::Target: EntropySource,
 320 {
 321         pub(crate) fn find_path(
 322                 network_graph: &G, _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 = 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         pub(crate) fn create_blinded_paths<
 350                 T: secp256k1::Signing + secp256k1::Verification
 351         >(
 352                 network_graph: &G, recipient: PublicKey, peers: Vec<PublicKey>, entropy_source: &ES,
 353                 secp_ctx: &Secp256k1<T>,
 354         ) -> Result<Vec<BlindedPath>, ()> {
 355                 // Limit the number of blinded paths that are computed.
 356                 const MAX_PATHS: usize = 3;
 357
 358                 // Ensure peers have at least three channels so that it is more difficult to infer the
 359                 // recipient's node_id.
 360                 const MIN_PEER_CHANNELS: usize = 3;
 361
 362                 let network_graph = network_graph.deref().read_only();
 363                 let paths = peers.iter()
 364                         // Limit to peers with announced channels
 365                         .filter(|pubkey|
 366                                 network_graph
 367                                         .node(&NodeId::from_pubkey(pubkey))
 368                                         .map(|info| &info.channels[..])
 369                                         .map(|channels| channels.len() >= MIN_PEER_CHANNELS)
 370                                         .unwrap_or(false)
 371                         )
 372                         .map(|pubkey| vec![*pubkey, recipient])
 373                         .map(|node_pks| BlindedPath::new_for_message(&node_pks, &**entropy_source, secp_ctx))
 374                         .take(MAX_PATHS)
 375                         .collect::<Result<Vec<_>, _>>();
 376
 377                 match paths {
 378                         Ok(paths) if !paths.is_empty() => Ok(paths),
 379                         _ => {
 380                                 if network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient)) {
 381                                         BlindedPath::one_hop_for_message(recipient, &**entropy_source, secp_ctx)
 382                                                 .map(|path| vec![path])
 383                                 } else {
 384                                         Err(())
 385                                 }
 386                         },
 387                 }
 388         }
 389 }
 390
 391 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> MessageRouter for DefaultMessageRouter<G, L, ES>
 392 where
 393         L::Target: Logger,
 394         ES::Target: EntropySource,
 395 {
 396         fn find_path(
 397                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 398         ) -> Result<OnionMessagePath, ()> {
 399                 Self::find_path(&self.network_graph, sender, peers, destination)
 400         }
 401
 402         fn create_blinded_paths<
 403                 T: secp256k1::Signing + secp256k1::Verification
 404         >(
 405                 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 406         ) -> Result<Vec<BlindedPath>, ()> {
 407                 Self::create_blinded_paths(&self.network_graph, recipient, peers, &self.entropy_source, secp_ctx)
 408         }
 409 }
 410
 411 /// A path for sending an [`OnionMessage`].
 412 #[derive(Clone)]
 413 pub struct OnionMessagePath {
 414         /// Nodes on the path between the sender and the destination.
 415         pub intermediate_nodes: Vec<PublicKey>,
 416
 417         /// The recipient of the message.
 418         pub destination: Destination,
 419
 420         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 421         ///
 422         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 423         /// this to initiate such a connection.
 424         pub first_node_addresses: Option<Vec<SocketAddress>>,
 425 }
 426
 427 impl OnionMessagePath {
 428         /// Returns the first node in the path.
 429         pub fn first_node(&self) -> PublicKey {
 430                 self.intermediate_nodes
 431                         .first()
 432                         .copied()
 433                         .unwrap_or_else(|| self.destination.first_node())
 434         }
 435 }
 436
 437 /// The destination of an onion message.
 438 #[derive(Clone)]
 439 pub enum Destination {
 440         /// We're sending this onion message to a node.
 441         Node(PublicKey),
 442         /// We're sending this onion message to a blinded path.
 443         BlindedPath(BlindedPath),
 444 }
 445
 446 impl Destination {
 447         pub(super) fn num_hops(&self) -> usize {
 448                 match self {
 449                         Destination::Node(_) => 1,
 450                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 451                 }
 452         }
 453
 454         fn first_node(&self) -> PublicKey {
 455                 match self {
 456                         Destination::Node(node_id) => *node_id,
 457                         Destination::BlindedPath(BlindedPath { introduction_node_id: node_id, .. }) => *node_id,
 458                 }
 459         }
 460 }
 461
 462 /// Result of successfully [sending an onion message].
 463 ///
 464 /// [sending an onion message]: OnionMessenger::send_onion_message
 465 #[derive(Debug, PartialEq, Eq)]
 466 pub enum SendSuccess {
 467         /// The message was buffered and will be sent once it is processed by
 468         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 469         Buffered,
 470         /// The message was buffered and will be sent once the node is connected as a peer and it is
 471         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 472         BufferedAwaitingConnection(PublicKey),
 473 }
 474
 475 /// Errors that may occur when [sending an onion message].
 476 ///
 477 /// [sending an onion message]: OnionMessenger::send_onion_message
 478 #[derive(Debug, PartialEq, Eq)]
 479 pub enum SendError {
 480         /// Errored computing onion message packet keys.
 481         Secp256k1(secp256k1::Error),
 482         /// Because implementations such as Eclair will drop onion messages where the message packet
 483         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 484         TooBigPacket,
 485         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 486         /// hops.
 487         TooFewBlindedHops,
 488         /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
 489         InvalidFirstHop(PublicKey),
 490         /// A path from the sender to the destination could not be found by the [`MessageRouter`].
 491         PathNotFound,
 492         /// Onion message contents must have a TLV type >= 64.
 493         InvalidMessage,
 494         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 495         BufferFull,
 496         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 497         ///
 498         /// [`NodeSigner`]: crate::sign::NodeSigner
 499         GetNodeIdFailed,
 500         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 501         /// advance the blinded path to make the second hop the new introduction node. Either
 502         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 503         /// new blinding point, or we were attempting to send to ourselves.
 504         BlindedPathAdvanceFailed,
 505 }
 506
 507 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 508 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 509 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 510 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 511 /// message types.
 512 ///
 513 /// See [`OnionMessenger`] for example usage.
 514 ///
 515 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 516 /// [`CustomMessage`]: Self::CustomMessage
 517 pub trait CustomOnionMessageHandler {
 518         /// The message known to the handler. To support multiple message types, you may want to make this
 519         /// an enum with a variant for each supported message.
 520         type CustomMessage: OnionMessageContents;
 521
 522         /// Called with the custom message that was received, returning a response to send, if any.
 523         ///
 524         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 525         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 526
 527         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 528         /// message type is unknown.
 529         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 530
 531         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 532         ///
 533         /// Typically, this is used for messages initiating a message flow rather than in response to
 534         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 535         #[cfg(not(c_bindings))]
 536         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 537
 538         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 539         ///
 540         /// Typically, this is used for messages initiating a message flow rather than in response to
 541         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 542         #[cfg(c_bindings)]
 543         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 544 }
 545
 546 /// A processed incoming onion message, containing either a Forward (another onion message)
 547 /// or a Receive payload with decrypted contents.
 548 pub enum PeeledOnion<T: OnionMessageContents> {
 549         /// Forwarded onion, with the next node id and a new onion
 550         Forward(PublicKey, OnionMessage),
 551         /// Received onion message, with decrypted contents, path_id, and reply path
 552         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 553 }
 554
 555 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 556 /// `path`.
 557 ///
 558 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 559 /// need to connect to the first node.
 560 pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
 561         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 562         path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 563 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 564 where
 565         ES::Target: EntropySource,
 566         NS::Target: NodeSigner,
 567 {
 568         let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
 569         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 570                 if blinded_hops.is_empty() {
 571                         return Err(SendError::TooFewBlindedHops);
 572                 }
 573         }
 574
 575         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 576
 577         // If we are sending straight to a blinded path and we are the introduction node, we need to
 578         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 579         if intermediate_nodes.len() == 0 {
 580                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 581                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 582                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 583                         if blinded_path.introduction_node_id == our_node_id {
 584                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 585                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 586                         }
 587                 }
 588         }
 589
 590         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 591         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 592         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 593                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 594         } else {
 595                 match destination {
 596                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 597                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 598                                 (introduction_node_id, blinding_point),
 599                 }
 600         };
 601         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 602                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret)
 603                 .map_err(|e| SendError::Secp256k1(e))?;
 604
 605         let prng_seed = entropy_source.get_secure_random_bytes();
 606         let onion_routing_packet = construct_onion_message_packet(
 607                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 608
 609         let message = OnionMessage { blinding_point, onion_routing_packet };
 610         Ok((first_node_id, message, first_node_addresses))
 611 }
 612
 613 /// Decode one layer of an incoming [`OnionMessage`].
 614 ///
 615 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 616 /// receiver.
 617 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 618         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 619         custom_handler: CMH,
 620 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 621 where
 622         NS::Target: NodeSigner,
 623         L::Target: Logger,
 624         CMH::Target: CustomOnionMessageHandler,
 625 {
 626         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 627                 Ok(ss) => ss,
 628                 Err(e) =>  {
 629                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 630                         return Err(());
 631                 }
 632         };
 633         let onion_decode_ss = {
 634                 let blinding_factor = {
 635                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 636                         hmac.input(control_tlvs_ss.as_ref());
 637                         Hmac::from_engine(hmac).to_byte_array()
 638                 };
 639                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 640                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 641                 {
 642                         Ok(ss) => ss.secret_bytes(),
 643                         Err(()) => {
 644                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 645                                 return Err(());
 646                         }
 647                 }
 648         };
 649         match onion_utils::decode_next_untagged_hop(
 650                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 651                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 652         ) {
 653                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 654                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 655                 }, None)) => {
 656                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 657                 },
 658                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 659                         next_node_id, next_blinding_override
 660                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 661                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 662                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 663                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 664                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 665                         // for now.
 666                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 667                                 Ok(pk) => pk,
 668                                 Err(e) => {
 669                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 670                                         return Err(())
 671                                 }
 672                         };
 673                         let outgoing_packet = Packet {
 674                                 version: 0,
 675                                 public_key: new_pubkey,
 676                                 hop_data: new_packet_bytes,
 677                                 hmac: next_hop_hmac,
 678                         };
 679                         let onion_message = OnionMessage {
 680                                 blinding_point: match next_blinding_override {
 681                                         Some(blinding_point) => blinding_point,
 682                                         None => {
 683                                                 match onion_utils::next_hop_pubkey(
 684                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 685                                                 ) {
 686                                                         Ok(bp) => bp,
 687                                                         Err(e) => {
 688                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 689                                                                 return Err(())
 690                                                         }
 691                                                 }
 692                                         }
 693                                 },
 694                                 onion_routing_packet: outgoing_packet,
 695                         };
 696
 697                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 698                 },
 699                 Err(e) => {
 700                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 701                         Err(())
 702                 },
 703                 _ => {
 704                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 705                         Err(())
 706                 },
 707         }
 708 }
 709
 710 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 711 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 712 where
 713         ES::Target: EntropySource,
 714         NS::Target: NodeSigner,
 715         L::Target: Logger,
 716         MR::Target: MessageRouter,
 717         OMH::Target: OffersMessageHandler,
 718         CMH::Target: CustomOnionMessageHandler,
 719 {
 720         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 721         /// their respective handlers.
 722         pub fn new(
 723                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 724                 custom_handler: CMH
 725         ) -> Self {
 726                 let mut secp_ctx = Secp256k1::new();
 727                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 728                 OnionMessenger {
 729                         entropy_source,
 730                         node_signer,
 731                         message_recipients: Mutex::new(HashMap::new()),
 732                         secp_ctx,
 733                         logger,
 734                         message_router,
 735                         offers_handler,
 736                         custom_handler,
 737                 }
 738         }
 739
 740         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
 741         ///
 742         /// See [`OnionMessenger`] for example usage.
 743         pub fn send_onion_message<T: OnionMessageContents>(
 744                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
 745         ) -> Result<SendSuccess, SendError> {
 746                 self.find_path_and_enqueue_onion_message(
 747                         contents, destination, reply_path, format_args!("")
 748                 )
 749         }
 750
 751         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 752                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 753                 log_suffix: fmt::Arguments
 754         ) -> Result<SendSuccess, SendError> {
 755                 let result = self.find_path(destination)
 756                         .and_then(|path| self.enqueue_onion_message(path, contents, reply_path, log_suffix));
 757
 758                 match result.as_ref() {
 759                         Err(SendError::GetNodeIdFailed) => {
 760                                 log_warn!(self.logger, "Unable to retrieve node id {}", log_suffix);
 761                         },
 762                         Err(SendError::PathNotFound) => {
 763                                 log_trace!(self.logger, "Failed to find path {}", log_suffix);
 764                         },
 765                         Err(e) => {
 766                                 log_trace!(self.logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 767                         },
 768                         Ok(SendSuccess::Buffered) => {
 769                                 log_trace!(self.logger, "Buffered onion message {}", log_suffix);
 770                         },
 771                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
 772                                 log_trace!(
 773                                         self.logger, "Buffered onion message waiting on peer connection {}: {:?}",
 774                                         log_suffix, node_id
 775                                 );
 776                         },
 777                 }
 778
 779                 result
 780         }
 781
 782         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
 783                 let sender = self.node_signer
 784                         .get_node_id(Recipient::Node)
 785                         .map_err(|_| SendError::GetNodeIdFailed)?;
 786
 787                 let peers = self.message_recipients.lock().unwrap()
 788                         .iter()
 789                         .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
 790                         .map(|(node_id, _)| *node_id)
 791                         .collect();
 792
 793                 self.message_router
 794                         .find_path(sender, peers, destination)
 795                         .map_err(|_| SendError::PathNotFound)
 796         }
 797
 798         fn enqueue_onion_message<T: OnionMessageContents>(
 799                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 800                 log_suffix: fmt::Arguments
 801         ) -> Result<SendSuccess, SendError> {
 802                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 803
 804                 let (first_node_id, onion_message, addresses) = create_onion_message(
 805                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
 806                 )?;
 807
 808                 let mut message_recipients = self.message_recipients.lock().unwrap();
 809                 if outbound_buffer_full(&first_node_id, &message_recipients) {
 810                         return Err(SendError::BufferFull);
 811                 }
 812
 813                 match message_recipients.entry(first_node_id) {
 814                         hash_map::Entry::Vacant(e) => match addresses {
 815                                 None => Err(SendError::InvalidFirstHop(first_node_id)),
 816                                 Some(addresses) => {
 817                                         e.insert(OnionMessageRecipient::pending_connection(addresses))
 818                                                 .enqueue_message(onion_message);
 819                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 820                                 },
 821                         },
 822                         hash_map::Entry::Occupied(mut e) => {
 823                                 e.get_mut().enqueue_message(onion_message);
 824                                 if e.get().is_connected() {
 825                                         Ok(SendSuccess::Buffered)
 826                                 } else {
 827                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 828                                 }
 829                         },
 830                 }
 831         }
 832
 833         #[cfg(test)]
 834         pub(super) fn send_onion_message_using_path<T: OnionMessageContents>(
 835                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
 836         ) -> Result<SendSuccess, SendError> {
 837                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
 838         }
 839
 840         fn handle_onion_message_response<T: OnionMessageContents>(
 841                 &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
 842         ) {
 843                 if let Some(response) = response {
 844                         match reply_path {
 845                                 Some(reply_path) => {
 846                                         let _ = self.find_path_and_enqueue_onion_message(
 847                                                 response, Destination::BlindedPath(reply_path), None, log_suffix
 848                                         );
 849                                 },
 850                                 None => {
 851                                         log_trace!(self.logger, "Missing reply path {}", log_suffix);
 852                                 },
 853                         }
 854                 }
 855         }
 856
 857         #[cfg(test)]
 858         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 859                 let mut message_recipients = self.message_recipients.lock().unwrap();
 860                 let mut msgs = HashMap::new();
 861                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 862                 // release the pending message buffers individually.
 863                 for (node_id, recipient) in &mut *message_recipients {
 864                         msgs.insert(*node_id, recipient.release_pending_messages());
 865                 }
 866                 msgs
 867         }
 868 }
 869
 870 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
 871         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 872         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 873         let mut total_buffered_bytes = 0;
 874         let mut peer_buffered_bytes = 0;
 875         for (pk, peer_buf) in buffer {
 876                 for om in peer_buf.pending_messages() {
 877                         let om_len = om.serialized_length();
 878                         if pk == peer_node_id {
 879                                 peer_buffered_bytes += om_len;
 880                         }
 881                         total_buffered_bytes += om_len;
 882
 883                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 884                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 885                         {
 886                                 return true
 887                         }
 888                 }
 889         }
 890         false
 891 }
 892
 893 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
 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 process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
 904                 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
 905                         if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
 906                                 if let Some(addresses) = addresses.take() {
 907                                         handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
 908                                 }
 909                         }
 910                 }
 911         }
 912 }
 913
 914 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 915 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 916 where
 917         ES::Target: EntropySource,
 918         NS::Target: NodeSigner,
 919         L::Target: Logger,
 920         MR::Target: MessageRouter,
 921         OMH::Target: OffersMessageHandler,
 922         CMH::Target: CustomOnionMessageHandler,
 923 {
 924         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
 925                 match peel_onion_message(
 926                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
 927                 ) {
 928                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 929                                 log_trace!(
 930                                         self.logger,
 931                                    "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
 932                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
 933
 934                                 match message {
 935                                         ParsedOnionMessageContents::Offers(msg) => {
 936                                                 let response = self.offers_handler.handle_message(msg);
 937                                                 self.handle_onion_message_response(
 938                                                         response, reply_path, format_args!(
 939                                                                 "when responding to Offers onion message with path_id {:02x?}",
 940                                                                 path_id
 941                                                         )
 942                                                 );
 943                                         },
 944                                         ParsedOnionMessageContents::Custom(msg) => {
 945                                                 let response = self.custom_handler.handle_custom_message(msg);
 946                                                 self.handle_onion_message_response(
 947                                                         response, reply_path, format_args!(
 948                                                                 "when responding to Custom onion message with path_id {:02x?}",
 949                                                                 path_id
 950                                                         )
 951                                                 );
 952                                         },
 953                                 }
 954                         },
 955                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 956                                 let mut message_recipients = self.message_recipients.lock().unwrap();
 957                                 if outbound_buffer_full(&next_node_id, &message_recipients) {
 958                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 959                                         return
 960                                 }
 961
 962                                 #[cfg(fuzzing)]
 963                                 message_recipients
 964                                         .entry(next_node_id)
 965                                         .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
 966
 967                                 match message_recipients.entry(next_node_id) {
 968                                         hash_map::Entry::Occupied(mut e) if matches!(
 969                                                 e.get(), OnionMessageRecipient::ConnectedPeer(..)
 970                                         ) => {
 971                                                 e.get_mut().enqueue_message(onion_message);
 972                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 973                                         },
 974                                         _ => {
 975                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 976                                                 return
 977                                         },
 978                                 }
 979                         },
 980                         Err(e) => {
 981                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
 982                         }
 983                 }
 984         }
 985
 986         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 987                 if init.features.supports_onion_messages() {
 988                         self.message_recipients.lock().unwrap()
 989                                 .entry(*their_node_id)
 990                                 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
 991                                 .mark_connected();
 992                 } else {
 993                         self.message_recipients.lock().unwrap().remove(their_node_id);
 994                 }
 995
 996                 Ok(())
 997         }
 998
 999         fn peer_disconnected(&self, their_node_id: &PublicKey) {
1000                 match self.message_recipients.lock().unwrap().remove(their_node_id) {
1001                         Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
1002                         Some(_) => debug_assert!(false),
1003                         None => {},
1004                 }
1005         }
1006
1007         fn timer_tick_occurred(&self) {
1008                 let mut message_recipients = self.message_recipients.lock().unwrap();
1009
1010                 // Drop any pending recipients since the last call to avoid retaining buffered messages for
1011                 // too long.
1012                 message_recipients.retain(|_, recipient| match recipient {
1013                         OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
1014                         OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
1015                         _ => true,
1016                 });
1017
1018                 // Increment a timer tick for pending recipients so that their buffered messages are dropped
1019                 // at MAX_TIMER_TICKS.
1020                 for recipient in message_recipients.values_mut() {
1021                         if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
1022                                 *ticks += 1;
1023                         }
1024                 }
1025         }
1026
1027         fn provided_node_features(&self) -> NodeFeatures {
1028                 let mut features = NodeFeatures::empty();
1029                 features.set_onion_messages_optional();
1030                 features
1031         }
1032
1033         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1034                 let mut features = InitFeatures::empty();
1035                 features.set_onion_messages_optional();
1036                 features
1037         }
1038
1039         // Before returning any messages to send for the peer, this method will see if any messages were
1040         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1041         // node, and then enqueue the message for sending to the first peer in the full path.
1042         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1043                 // Enqueue any initiating `OffersMessage`s to send.
1044                 for message in self.offers_handler.release_pending_messages() {
1045                         #[cfg(not(c_bindings))]
1046                         let PendingOnionMessage { contents, destination, reply_path } = message;
1047                         #[cfg(c_bindings)]
1048                         let (contents, destination, reply_path) = message;
1049                         let _ = self.find_path_and_enqueue_onion_message(
1050                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
1051                         );
1052                 }
1053
1054                 // Enqueue any initiating `CustomMessage`s to send.
1055                 for message in self.custom_handler.release_pending_custom_messages() {
1056                         #[cfg(not(c_bindings))]
1057                         let PendingOnionMessage { contents, destination, reply_path } = message;
1058                         #[cfg(c_bindings)]
1059                         let (contents, destination, reply_path) = message;
1060                         let _ = self.find_path_and_enqueue_onion_message(
1061                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
1062                         );
1063                 }
1064
1065                 self.message_recipients.lock().unwrap()
1066                         .get_mut(&peer_node_id)
1067                         .and_then(|buffer| buffer.dequeue_message())
1068         }
1069 }
1070
1071 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1072 // produces
1073 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1074 /// [`SimpleArcPeerManager`]. See their docs for more details.
1075 ///
1076 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1077 ///
1078 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1079 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1080 #[cfg(not(c_bindings))]
1081 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1082         Arc<KeysManager>,
1083         Arc<KeysManager>,
1084         Arc<L>,
1085         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>, Arc<KeysManager>>>,
1086         Arc<SimpleArcChannelManager<M, T, F, L>>,
1087         IgnoringMessageHandler
1088 >;
1089
1090 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1091 /// [`SimpleRefPeerManager`]. See their docs for more details.
1092 ///
1093 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1094 ///
1095 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1096 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1097 #[cfg(not(c_bindings))]
1098 pub type SimpleRefOnionMessenger<
1099         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1100 > = OnionMessenger<
1101         &'a KeysManager,
1102         &'a KeysManager,
1103         &'b L,
1104         &'i DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L, &'a KeysManager>,
1105         &'j SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1106         IgnoringMessageHandler
1107 >;
1108
1109 /// Construct onion packet payloads and keys for sending an onion message along the given
1110 /// `unblinded_path` to the given `destination`.
1111 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1112         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1113         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1114 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
1115         let num_hops = unblinded_path.len() + destination.num_hops();
1116         let mut payloads = Vec::with_capacity(num_hops);
1117         let mut onion_packet_keys = Vec::with_capacity(num_hops);
1118
1119         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
1120                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
1121                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
1122         let num_unblinded_hops = num_hops - num_blinded_hops;
1123
1124         let mut unblinded_path_idx = 0;
1125         let mut blinded_path_idx = 0;
1126         let mut prev_control_tlvs_ss = None;
1127         let mut final_control_tlvs = None;
1128         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1129                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1130                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1131                                 if let Some(ss) = prev_control_tlvs_ss.take() {
1132                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1133                                                 ForwardTlvs {
1134                                                         next_node_id: unblinded_pk_opt.unwrap(),
1135                                                         next_blinding_override: None,
1136                                                 }
1137                                         )), ss));
1138                                 }
1139                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1140                                 unblinded_path_idx += 1;
1141                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1142                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1143                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1144                                                 next_node_id: intro_node_id,
1145                                                 next_blinding_override: Some(blinding_pt),
1146                                         })), control_tlvs_ss));
1147                                 }
1148                         }
1149                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1150                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1151                                         control_tlvs_ss));
1152                                 blinded_path_idx += 1;
1153                         } else if let Some(encrypted_payload) = enc_payload_opt {
1154                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1155                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1156                         }
1157
1158                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1159                         onion_packet_keys.push(onion_utils::OnionKeys {
1160                                 #[cfg(test)]
1161                                 shared_secret: onion_packet_ss,
1162                                 #[cfg(test)]
1163                                 blinding_factor: [0; 32],
1164                                 ephemeral_pubkey,
1165                                 rho,
1166                                 mu,
1167                         });
1168                 }
1169         )?;
1170
1171         if let Some(control_tlvs) = final_control_tlvs {
1172                 payloads.push((Payload::Receive {
1173                         control_tlvs,
1174                         reply_path: reply_path.take(),
1175                         message,
1176                 }, prev_control_tlvs_ss.unwrap()));
1177         } else {
1178                 payloads.push((Payload::Receive {
1179                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1180                         reply_path: reply_path.take(),
1181                         message,
1182                 }, prev_control_tlvs_ss.unwrap()));
1183         }
1184
1185         Ok((payloads, onion_packet_keys))
1186 }
1187
1188 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1189 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, ()> {
1190         // Spec rationale:
1191         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1192         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1193         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1194         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1195         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1196                 SMALL_PACKET_HOP_DATA_LEN
1197         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1198                 BIG_PACKET_HOP_DATA_LEN
1199         } else { return Err(()) };
1200
1201         onion_utils::construct_onion_message_packet::<_, _>(
1202                 payloads, onion_keys, prng_seed, hop_data_len)
1203 }