_ Git - rust-lightning/blob - lightning/src/onion_message/messenger.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! LDK sends, receives, and forwards onion messages via the [`OnionMessenger`]. See its docs for
  11 //! more information.
  12
  13 use bitcoin::hashes::{Hash, HashEngine};
  14 use bitcoin::hashes::hmac::{Hmac, HmacEngine};
  15 use bitcoin::hashes::sha256::Hash as Sha256;
  16 use bitcoin::secp256k1::{self, PublicKey, Scalar, Secp256k1, SecretKey};
  17
  18 use crate::blinded_path::BlindedPath;
  19 use crate::blinded_path::message::{advance_path_by_one, ForwardTlvs, ReceiveTlvs};
  20 use crate::blinded_path::utils;
  21 use crate::events::{Event, EventHandler, EventsProvider};
  22 use crate::sign::{EntropySource, KeysManager, 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::ln::peer_handler::IgnoringMessageHandler;
  29 use crate::routing::gossip::{NetworkGraph, NodeId};
  30 pub use super::packet::OnionMessageContents;
  31 use super::packet::ParsedOnionMessageContents;
  32 use super::offers::OffersMessageHandler;
  33 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  34 use crate::util::logger::Logger;
  35 use crate::util::ser::Writeable;
  36
  37 use core::fmt;
  38 use core::ops::Deref;
  39 use crate::io;
  40 use crate::sync::{Arc, Mutex};
  41 use crate::prelude::*;
  42
  43 pub(super) const MAX_TIMER_TICKS: usize = 2;
  44
  45 /// A sender, receiver and forwarder of [`OnionMessage`]s.
  46 ///
  47 /// # Handling Messages
  48 ///
  49 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
  50 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
  51 /// available handlers are:
  52 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
  53 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
  54 ///
  55 /// # Sending Messages
  56 ///
  57 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
  58 /// a message, the matched handler may return a response message which `OnionMessenger` will send
  59 /// on its behalf.
  60 ///
  61 /// # Example
  62 ///
  63 /// ```
  64 /// # extern crate bitcoin;
  65 /// # use bitcoin::hashes::_export::_core::time::Duration;
  66 /// # use bitcoin::hashes::hex::FromHex;
  67 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey, self};
  68 /// # use lightning::blinded_path::BlindedPath;
  69 /// # use lightning::sign::{EntropySource, KeysManager};
  70 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  71 /// # use lightning::onion_message::{OnionMessageContents, Destination, MessageRouter, OnionMessagePath, OnionMessenger};
  72 /// # use lightning::util::logger::{Logger, Record};
  73 /// # use lightning::util::ser::{Writeable, Writer};
  74 /// # use lightning::io;
  75 /// # use std::sync::Arc;
  76 /// # struct FakeLogger;
  77 /// # impl Logger for FakeLogger {
  78 /// #     fn log(&self, record: Record) { println!("{:?}" , record); }
  79 /// # }
  80 /// # struct FakeMessageRouter {}
  81 /// # impl MessageRouter for FakeMessageRouter {
  82 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  83 /// #         let secp_ctx = Secp256k1::new();
  84 /// #         let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  85 /// #         let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  86 /// #         let hop_node_id2 = hop_node_id1;
  87 /// #         Ok(OnionMessagePath {
  88 /// #             intermediate_nodes: vec![hop_node_id1, hop_node_id2],
  89 /// #             destination,
  90 /// #             first_node_addresses: None,
  91 /// #         })
  92 /// #     }
  93 /// #     fn create_blinded_paths<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
  94 /// #         &self, _recipient: PublicKey, _peers: Vec<PublicKey>, _entropy_source: &ES, _secp_ctx: &Secp256k1<T>
  95 /// #     ) -> Result<Vec<BlindedPath>, ()> {
  96 /// #         unreachable!()
  97 /// #     }
  98 /// # }
  99 /// # let seed = [42u8; 32];
 100 /// # let time = Duration::from_secs(123456);
 101 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
 102 /// # let logger = Arc::new(FakeLogger {});
 103 /// # let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
 104 /// # let secp_ctx = Secp256k1::new();
 105 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
 106 /// # let (hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1);
 107 /// # let destination_node_id = hop_node_id1;
 108 /// # let message_router = Arc::new(FakeMessageRouter {});
 109 /// # let custom_message_handler = IgnoringMessageHandler {};
 110 /// # let offers_message_handler = IgnoringMessageHandler {};
 111 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
 112 /// // ChannelManager.
 113 /// let onion_messenger = OnionMessenger::new(
 114 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
 115 ///     &custom_message_handler
 116 /// );
 117
 118 /// # #[derive(Debug)]
 119 /// # struct YourCustomMessage {}
 120 /// impl Writeable for YourCustomMessage {
 121 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 122 ///             # Ok(())
 123 ///             // Write your custom onion message to `w`
 124 ///     }
 125 /// }
 126 /// impl OnionMessageContents for YourCustomMessage {
 127 ///     fn tlv_type(&self) -> u64 {
 128 ///             # let your_custom_message_type = 42;
 129 ///             your_custom_message_type
 130 ///     }
 131 /// }
 132 /// // Send a custom onion message to a node id.
 133 /// let destination = Destination::Node(destination_node_id);
 134 /// let reply_path = None;
 135 /// # let message = YourCustomMessage {};
 136 /// onion_messenger.send_onion_message(message, destination, reply_path);
 137 ///
 138 /// // Create a blinded path to yourself, for someone to send an onion message to.
 139 /// # let your_node_id = hop_node_id1;
 140 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 141 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 142 ///
 143 /// // Send a custom onion message to a blinded path.
 144 /// let destination = Destination::BlindedPath(blinded_path);
 145 /// let reply_path = None;
 146 /// # let message = YourCustomMessage {};
 147 /// onion_messenger.send_onion_message(message, destination, reply_path);
 148 /// ```
 149 ///
 150 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 151 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 152 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 153 where
 154         ES::Target: EntropySource,
 155         NS::Target: NodeSigner,
 156         L::Target: Logger,
 157         MR::Target: MessageRouter,
 158         OMH::Target: OffersMessageHandler,
 159         CMH::Target: CustomOnionMessageHandler,
 160 {
 161         entropy_source: ES,
 162         node_signer: NS,
 163         logger: L,
 164         message_recipients: Mutex<HashMap<PublicKey, OnionMessageRecipient>>,
 165         secp_ctx: Secp256k1<secp256k1::All>,
 166         message_router: MR,
 167         offers_handler: OMH,
 168         custom_handler: CMH,
 169 }
 170
 171 /// [`OnionMessage`]s buffered to be sent.
 172 enum OnionMessageRecipient {
 173         /// Messages for a node connected as a peer.
 174         ConnectedPeer(VecDeque<OnionMessage>),
 175
 176         /// Messages for a node that is not yet connected, which are dropped after [`MAX_TIMER_TICKS`]
 177         /// and tracked here.
 178         PendingConnection(VecDeque<OnionMessage>, Option<Vec<SocketAddress>>, usize),
 179 }
 180
 181 impl OnionMessageRecipient {
 182         fn pending_connection(addresses: Vec<SocketAddress>) -> Self {
 183                 Self::PendingConnection(VecDeque::new(), Some(addresses), 0)
 184         }
 185
 186         fn pending_messages(&self) -> &VecDeque<OnionMessage> {
 187                 match self {
 188                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 189                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 190                 }
 191         }
 192
 193         fn enqueue_message(&mut self, message: OnionMessage) {
 194                 let pending_messages = match self {
 195                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 196                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 197                 };
 198
 199                 pending_messages.push_back(message);
 200         }
 201
 202         fn dequeue_message(&mut self) -> Option<OnionMessage> {
 203                 let pending_messages = match self {
 204                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 205                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => {
 206                                 debug_assert!(false);
 207                                 pending_messages
 208                         },
 209                 };
 210
 211                 pending_messages.pop_front()
 212         }
 213
 214         #[cfg(test)]
 215         fn release_pending_messages(&mut self) -> VecDeque<OnionMessage> {
 216                 let pending_messages = match self {
 217                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 218                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 219                 };
 220
 221                 core::mem::take(pending_messages)
 222         }
 223
 224         fn mark_connected(&mut self) {
 225                 if let OnionMessageRecipient::PendingConnection(pending_messages, _, _) = self {
 226                         let mut new_pending_messages = VecDeque::new();
 227                         core::mem::swap(pending_messages, &mut new_pending_messages);
 228                         *self = OnionMessageRecipient::ConnectedPeer(new_pending_messages);
 229                 }
 230         }
 231
 232         fn is_connected(&self) -> bool {
 233                 match self {
 234                         OnionMessageRecipient::ConnectedPeer(..) => true,
 235                         OnionMessageRecipient::PendingConnection(..) => false,
 236                 }
 237         }
 238 }
 239
 240 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 241 ///
 242 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 243 /// enqueued for sending.
 244 #[cfg(not(c_bindings))]
 245 pub struct PendingOnionMessage<T: OnionMessageContents> {
 246         /// The message contents to send in an [`OnionMessage`].
 247         pub contents: T,
 248
 249         /// The destination of the message.
 250         pub destination: Destination,
 251
 252         /// A reply path to include in the [`OnionMessage`] for a response.
 253         pub reply_path: Option<BlindedPath>,
 254 }
 255
 256 #[cfg(c_bindings)]
 257 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 258 ///
 259 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 260 /// enqueued for sending.
 261 pub type PendingOnionMessage<T: OnionMessageContents> = (T, Destination, Option<BlindedPath>);
 262
 263 pub(crate) fn new_pending_onion_message<T: OnionMessageContents>(
 264         contents: T, destination: Destination, reply_path: Option<BlindedPath>
 265 ) -> PendingOnionMessage<T> {
 266         #[cfg(not(c_bindings))]
 267         return PendingOnionMessage { contents, destination, reply_path };
 268         #[cfg(c_bindings)]
 269         return (contents, destination, reply_path);
 270 }
 271
 272 /// A trait defining behavior for routing an [`OnionMessage`].
 273 pub trait MessageRouter {
 274         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 275         fn find_path(
 276                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 277         ) -> Result<OnionMessagePath, ()>;
 278
 279         /// Creates [`BlindedPath`]s to the `recipient` node. The nodes in `peers` are assumed to be
 280         /// direct peers with the `recipient`.
 281         fn create_blinded_paths<
 282                 ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification
 283         >(
 284                 &self, recipient: PublicKey, peers: Vec<PublicKey>, entropy_source: &ES,
 285                 secp_ctx: &Secp256k1<T>
 286         ) -> Result<Vec<BlindedPath>, ()>;
 287 }
 288
 289 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
 290 pub struct DefaultMessageRouter<G: Deref<Target=NetworkGraph<L>>, L: Deref>
 291 where
 292         L::Target: Logger,
 293 {
 294         network_graph: G,
 295 }
 296
 297 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref> DefaultMessageRouter<G, L>
 298 where
 299         L::Target: Logger,
 300 {
 301         /// Creates a [`DefaultMessageRouter`] using the given [`NetworkGraph`].
 302         pub fn new(network_graph: G) -> Self {
 303                 Self { network_graph }
 304         }
 305 }
 306
 307 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref> MessageRouter for DefaultMessageRouter<G, L>
 308 where
 309         L::Target: Logger,
 310 {
 311         fn find_path(
 312                 &self, _sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 313         ) -> Result<OnionMessagePath, ()> {
 314                 let first_node = destination.first_node();
 315                 if peers.contains(&first_node) {
 316                         Ok(OnionMessagePath {
 317                                 intermediate_nodes: vec![], destination, first_node_addresses: None
 318                         })
 319                 } else {
 320                         let network_graph = self.network_graph.deref().read_only();
 321                         let node_announcement = network_graph
 322                                 .node(&NodeId::from_pubkey(&first_node))
 323                                 .and_then(|node_info| node_info.announcement_info.as_ref())
 324                                 .and_then(|announcement_info| announcement_info.announcement_message.as_ref())
 325                                 .map(|node_announcement| &node_announcement.contents);
 326
 327                         match node_announcement {
 328                                 Some(node_announcement) if node_announcement.features.supports_onion_messages() => {
 329                                         let first_node_addresses = Some(node_announcement.addresses.clone());
 330                                         Ok(OnionMessagePath {
 331                                                 intermediate_nodes: vec![], destination, first_node_addresses
 332                                         })
 333                                 },
 334                                 _ => Err(()),
 335                         }
 336                 }
 337         }
 338
 339         fn create_blinded_paths<
 340                 ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification
 341         >(
 342                 &self, recipient: PublicKey, peers: Vec<PublicKey>, entropy_source: &ES,
 343                 secp_ctx: &Secp256k1<T>
 344         ) -> Result<Vec<BlindedPath>, ()> {
 345                 // Limit the number of blinded paths that are computed.
 346                 const MAX_PATHS: usize = 3;
 347
 348                 // Ensure peers have at least three channels so that it is more difficult to infer the
 349                 // recipient's node_id.
 350                 const MIN_PEER_CHANNELS: usize = 3;
 351
 352                 let network_graph = self.network_graph.deref().read_only();
 353                 let paths = peers.iter()
 354                         // Limit to peers with announced channels
 355                         .filter(|pubkey|
 356                                 network_graph
 357                                         .node(&NodeId::from_pubkey(pubkey))
 358                                         .map(|info| &info.channels[..])
 359                                         .map(|channels| channels.len() >= MIN_PEER_CHANNELS)
 360                                         .unwrap_or(false)
 361                         )
 362                         .map(|pubkey| vec![*pubkey, recipient])
 363                         .map(|node_pks| BlindedPath::new_for_message(&node_pks, entropy_source, secp_ctx))
 364                         .take(MAX_PATHS)
 365                         .collect::<Result<Vec<_>, _>>();
 366
 367                 match paths {
 368                         Ok(paths) if !paths.is_empty() => Ok(paths),
 369                         _ => {
 370                                 if network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient)) {
 371                                         BlindedPath::one_hop_for_message(recipient, entropy_source, secp_ctx)
 372                                                 .map(|path| vec![path])
 373                                 } else {
 374                                         Err(())
 375                                 }
 376                         },
 377                 }
 378         }
 379 }
 380
 381 /// A path for sending an [`OnionMessage`].
 382 #[derive(Clone)]
 383 pub struct OnionMessagePath {
 384         /// Nodes on the path between the sender and the destination.
 385         pub intermediate_nodes: Vec<PublicKey>,
 386
 387         /// The recipient of the message.
 388         pub destination: Destination,
 389
 390         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 391         ///
 392         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 393         /// this to initiate such a connection.
 394         pub first_node_addresses: Option<Vec<SocketAddress>>,
 395 }
 396
 397 impl OnionMessagePath {
 398         /// Returns the first node in the path.
 399         pub fn first_node(&self) -> PublicKey {
 400                 self.intermediate_nodes
 401                         .first()
 402                         .copied()
 403                         .unwrap_or_else(|| self.destination.first_node())
 404         }
 405 }
 406
 407 /// The destination of an onion message.
 408 #[derive(Clone)]
 409 pub enum Destination {
 410         /// We're sending this onion message to a node.
 411         Node(PublicKey),
 412         /// We're sending this onion message to a blinded path.
 413         BlindedPath(BlindedPath),
 414 }
 415
 416 impl Destination {
 417         pub(super) fn num_hops(&self) -> usize {
 418                 match self {
 419                         Destination::Node(_) => 1,
 420                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 421                 }
 422         }
 423
 424         fn first_node(&self) -> PublicKey {
 425                 match self {
 426                         Destination::Node(node_id) => *node_id,
 427                         Destination::BlindedPath(BlindedPath { introduction_node_id: node_id, .. }) => *node_id,
 428                 }
 429         }
 430 }
 431
 432 /// Result of successfully [sending an onion message].
 433 ///
 434 /// [sending an onion message]: OnionMessenger::send_onion_message
 435 #[derive(Debug, PartialEq, Eq)]
 436 pub enum SendSuccess {
 437         /// The message was buffered and will be sent once it is processed by
 438         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 439         Buffered,
 440         /// The message was buffered and will be sent once the node is connected as a peer and it is
 441         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 442         BufferedAwaitingConnection(PublicKey),
 443 }
 444
 445 /// Errors that may occur when [sending an onion message].
 446 ///
 447 /// [sending an onion message]: OnionMessenger::send_onion_message
 448 #[derive(Debug, PartialEq, Eq)]
 449 pub enum SendError {
 450         /// Errored computing onion message packet keys.
 451         Secp256k1(secp256k1::Error),
 452         /// Because implementations such as Eclair will drop onion messages where the message packet
 453         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 454         TooBigPacket,
 455         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 456         /// hops.
 457         TooFewBlindedHops,
 458         /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
 459         InvalidFirstHop(PublicKey),
 460         /// A path from the sender to the destination could not be found by the [`MessageRouter`].
 461         PathNotFound,
 462         /// Onion message contents must have a TLV type >= 64.
 463         InvalidMessage,
 464         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 465         BufferFull,
 466         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 467         ///
 468         /// [`NodeSigner`]: crate::sign::NodeSigner
 469         GetNodeIdFailed,
 470         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 471         /// advance the blinded path to make the second hop the new introduction node. Either
 472         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 473         /// new blinding point, or we were attempting to send to ourselves.
 474         BlindedPathAdvanceFailed,
 475 }
 476
 477 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 478 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 479 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 480 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 481 /// message types.
 482 ///
 483 /// See [`OnionMessenger`] for example usage.
 484 ///
 485 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 486 /// [`CustomMessage`]: Self::CustomMessage
 487 pub trait CustomOnionMessageHandler {
 488         /// The message known to the handler. To support multiple message types, you may want to make this
 489         /// an enum with a variant for each supported message.
 490         type CustomMessage: OnionMessageContents;
 491
 492         /// Called with the custom message that was received, returning a response to send, if any.
 493         ///
 494         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 495         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 496
 497         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 498         /// message type is unknown.
 499         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 500
 501         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 502         ///
 503         /// Typically, this is used for messages initiating a message flow rather than in response to
 504         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 505         #[cfg(not(c_bindings))]
 506         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 507
 508         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 509         ///
 510         /// Typically, this is used for messages initiating a message flow rather than in response to
 511         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 512         #[cfg(c_bindings)]
 513         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 514 }
 515
 516 /// A processed incoming onion message, containing either a Forward (another onion message)
 517 /// or a Receive payload with decrypted contents.
 518 pub enum PeeledOnion<T: OnionMessageContents> {
 519         /// Forwarded onion, with the next node id and a new onion
 520         Forward(PublicKey, OnionMessage),
 521         /// Received onion message, with decrypted contents, path_id, and reply path
 522         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 523 }
 524
 525 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 526 /// `path`.
 527 ///
 528 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 529 /// need to connect to the first node.
 530 pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
 531         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 532         path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 533 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 534 where
 535         ES::Target: EntropySource,
 536         NS::Target: NodeSigner,
 537 {
 538         let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
 539         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 540                 if blinded_hops.is_empty() {
 541                         return Err(SendError::TooFewBlindedHops);
 542                 }
 543         }
 544
 545         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 546
 547         // If we are sending straight to a blinded path and we are the introduction node, we need to
 548         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 549         if intermediate_nodes.len() == 0 {
 550                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 551                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 552                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 553                         if blinded_path.introduction_node_id == our_node_id {
 554                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 555                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 556                         }
 557                 }
 558         }
 559
 560         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 561         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 562         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 563                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 564         } else {
 565                 match destination {
 566                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 567                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 568                                 (introduction_node_id, blinding_point),
 569                 }
 570         };
 571         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 572                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret)
 573                 .map_err(|e| SendError::Secp256k1(e))?;
 574
 575         let prng_seed = entropy_source.get_secure_random_bytes();
 576         let onion_routing_packet = construct_onion_message_packet(
 577                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 578
 579         let message = OnionMessage { blinding_point, onion_routing_packet };
 580         Ok((first_node_id, message, first_node_addresses))
 581 }
 582
 583 /// Decode one layer of an incoming [`OnionMessage`].
 584 ///
 585 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 586 /// receiver.
 587 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 588         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 589         custom_handler: CMH,
 590 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 591 where
 592         NS::Target: NodeSigner,
 593         L::Target: Logger,
 594         CMH::Target: CustomOnionMessageHandler,
 595 {
 596         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 597                 Ok(ss) => ss,
 598                 Err(e) =>  {
 599                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 600                         return Err(());
 601                 }
 602         };
 603         let onion_decode_ss = {
 604                 let blinding_factor = {
 605                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 606                         hmac.input(control_tlvs_ss.as_ref());
 607                         Hmac::from_engine(hmac).to_byte_array()
 608                 };
 609                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 610                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 611                 {
 612                         Ok(ss) => ss.secret_bytes(),
 613                         Err(()) => {
 614                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 615                                 return Err(());
 616                         }
 617                 }
 618         };
 619         match onion_utils::decode_next_untagged_hop(
 620                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 621                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 622         ) {
 623                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 624                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 625                 }, None)) => {
 626                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 627                 },
 628                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 629                         next_node_id, next_blinding_override
 630                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 631                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 632                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 633                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 634                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 635                         // for now.
 636                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 637                                 Ok(pk) => pk,
 638                                 Err(e) => {
 639                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 640                                         return Err(())
 641                                 }
 642                         };
 643                         let outgoing_packet = Packet {
 644                                 version: 0,
 645                                 public_key: new_pubkey,
 646                                 hop_data: new_packet_bytes,
 647                                 hmac: next_hop_hmac,
 648                         };
 649                         let onion_message = OnionMessage {
 650                                 blinding_point: match next_blinding_override {
 651                                         Some(blinding_point) => blinding_point,
 652                                         None => {
 653                                                 match onion_utils::next_hop_pubkey(
 654                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 655                                                 ) {
 656                                                         Ok(bp) => bp,
 657                                                         Err(e) => {
 658                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 659                                                                 return Err(())
 660                                                         }
 661                                                 }
 662                                         }
 663                                 },
 664                                 onion_routing_packet: outgoing_packet,
 665                         };
 666
 667                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 668                 },
 669                 Err(e) => {
 670                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 671                         Err(())
 672                 },
 673                 _ => {
 674                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 675                         Err(())
 676                 },
 677         }
 678 }
 679
 680 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 681 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 682 where
 683         ES::Target: EntropySource,
 684         NS::Target: NodeSigner,
 685         L::Target: Logger,
 686         MR::Target: MessageRouter,
 687         OMH::Target: OffersMessageHandler,
 688         CMH::Target: CustomOnionMessageHandler,
 689 {
 690         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 691         /// their respective handlers.
 692         pub fn new(
 693                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 694                 custom_handler: CMH
 695         ) -> Self {
 696                 let mut secp_ctx = Secp256k1::new();
 697                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 698                 OnionMessenger {
 699                         entropy_source,
 700                         node_signer,
 701                         message_recipients: Mutex::new(HashMap::new()),
 702                         secp_ctx,
 703                         logger,
 704                         message_router,
 705                         offers_handler,
 706                         custom_handler,
 707                 }
 708         }
 709
 710         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
 711         ///
 712         /// See [`OnionMessenger`] for example usage.
 713         pub fn send_onion_message<T: OnionMessageContents>(
 714                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
 715         ) -> Result<SendSuccess, SendError> {
 716                 self.find_path_and_enqueue_onion_message(
 717                         contents, destination, reply_path, format_args!("")
 718                 )
 719         }
 720
 721         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 722                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 723                 log_suffix: fmt::Arguments
 724         ) -> Result<SendSuccess, SendError> {
 725                 let result = self.find_path(destination)
 726                         .and_then(|path| self.enqueue_onion_message(path, contents, reply_path, log_suffix));
 727
 728                 match result.as_ref() {
 729                         Err(SendError::GetNodeIdFailed) => {
 730                                 log_warn!(self.logger, "Unable to retrieve node id {}", log_suffix);
 731                         },
 732                         Err(SendError::PathNotFound) => {
 733                                 log_trace!(self.logger, "Failed to find path {}", log_suffix);
 734                         },
 735                         Err(e) => {
 736                                 log_trace!(self.logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 737                         },
 738                         Ok(SendSuccess::Buffered) => {
 739                                 log_trace!(self.logger, "Buffered onion message {}", log_suffix);
 740                         },
 741                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
 742                                 log_trace!(
 743                                         self.logger, "Buffered onion message waiting on peer connection {}: {:?}",
 744                                         log_suffix, node_id
 745                                 );
 746                         },
 747                 }
 748
 749                 result
 750         }
 751
 752         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
 753                 let sender = self.node_signer
 754                         .get_node_id(Recipient::Node)
 755                         .map_err(|_| SendError::GetNodeIdFailed)?;
 756
 757                 let peers = self.message_recipients.lock().unwrap()
 758                         .iter()
 759                         .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
 760                         .map(|(node_id, _)| *node_id)
 761                         .collect();
 762
 763                 self.message_router
 764                         .find_path(sender, peers, destination)
 765                         .map_err(|_| SendError::PathNotFound)
 766         }
 767
 768         fn enqueue_onion_message<T: OnionMessageContents>(
 769                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 770                 log_suffix: fmt::Arguments
 771         ) -> Result<SendSuccess, SendError> {
 772                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 773
 774                 let (first_node_id, onion_message, addresses) = create_onion_message(
 775                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
 776                 )?;
 777
 778                 let mut message_recipients = self.message_recipients.lock().unwrap();
 779                 if outbound_buffer_full(&first_node_id, &message_recipients) {
 780                         return Err(SendError::BufferFull);
 781                 }
 782
 783                 match message_recipients.entry(first_node_id) {
 784                         hash_map::Entry::Vacant(e) => match addresses {
 785                                 None => Err(SendError::InvalidFirstHop(first_node_id)),
 786                                 Some(addresses) => {
 787                                         e.insert(OnionMessageRecipient::pending_connection(addresses))
 788                                                 .enqueue_message(onion_message);
 789                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 790                                 },
 791                         },
 792                         hash_map::Entry::Occupied(mut e) => {
 793                                 e.get_mut().enqueue_message(onion_message);
 794                                 if e.get().is_connected() {
 795                                         Ok(SendSuccess::Buffered)
 796                                 } else {
 797                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 798                                 }
 799                         },
 800                 }
 801         }
 802
 803         #[cfg(test)]
 804         pub(super) fn send_onion_message_using_path<T: OnionMessageContents>(
 805                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
 806         ) -> Result<SendSuccess, SendError> {
 807                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
 808         }
 809
 810         fn handle_onion_message_response<T: OnionMessageContents>(
 811                 &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
 812         ) {
 813                 if let Some(response) = response {
 814                         match reply_path {
 815                                 Some(reply_path) => {
 816                                         let _ = self.find_path_and_enqueue_onion_message(
 817                                                 response, Destination::BlindedPath(reply_path), None, log_suffix
 818                                         );
 819                                 },
 820                                 None => {
 821                                         log_trace!(self.logger, "Missing reply path {}", log_suffix);
 822                                 },
 823                         }
 824                 }
 825         }
 826
 827         #[cfg(test)]
 828         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 829                 let mut message_recipients = self.message_recipients.lock().unwrap();
 830                 let mut msgs = HashMap::new();
 831                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 832                 // release the pending message buffers individually.
 833                 for (node_id, recipient) in &mut *message_recipients {
 834                         msgs.insert(*node_id, recipient.release_pending_messages());
 835                 }
 836                 msgs
 837         }
 838 }
 839
 840 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
 841         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 842         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 843         let mut total_buffered_bytes = 0;
 844         let mut peer_buffered_bytes = 0;
 845         for (pk, peer_buf) in buffer {
 846                 for om in peer_buf.pending_messages() {
 847                         let om_len = om.serialized_length();
 848                         if pk == peer_node_id {
 849                                 peer_buffered_bytes += om_len;
 850                         }
 851                         total_buffered_bytes += om_len;
 852
 853                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 854                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 855                         {
 856                                 return true
 857                         }
 858                 }
 859         }
 860         false
 861 }
 862
 863 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
 864 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 865 where
 866         ES::Target: EntropySource,
 867         NS::Target: NodeSigner,
 868         L::Target: Logger,
 869         MR::Target: MessageRouter,
 870         OMH::Target: OffersMessageHandler,
 871         CMH::Target: CustomOnionMessageHandler,
 872 {
 873         fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
 874                 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
 875                         if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
 876                                 if let Some(addresses) = addresses.take() {
 877                                         handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
 878                                 }
 879                         }
 880                 }
 881         }
 882 }
 883
 884 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 885 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 886 where
 887         ES::Target: EntropySource,
 888         NS::Target: NodeSigner,
 889         L::Target: Logger,
 890         MR::Target: MessageRouter,
 891         OMH::Target: OffersMessageHandler,
 892         CMH::Target: CustomOnionMessageHandler,
 893 {
 894         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
 895                 match peel_onion_message(
 896                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
 897                 ) {
 898                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 899                                 log_trace!(
 900                                         self.logger,
 901                                    "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
 902                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
 903
 904                                 match message {
 905                                         ParsedOnionMessageContents::Offers(msg) => {
 906                                                 let response = self.offers_handler.handle_message(msg);
 907                                                 self.handle_onion_message_response(
 908                                                         response, reply_path, format_args!(
 909                                                                 "when responding to Offers onion message with path_id {:02x?}",
 910                                                                 path_id
 911                                                         )
 912                                                 );
 913                                         },
 914                                         ParsedOnionMessageContents::Custom(msg) => {
 915                                                 let response = self.custom_handler.handle_custom_message(msg);
 916                                                 self.handle_onion_message_response(
 917                                                         response, reply_path, format_args!(
 918                                                                 "when responding to Custom onion message with path_id {:02x?}",
 919                                                                 path_id
 920                                                         )
 921                                                 );
 922                                         },
 923                                 }
 924                         },
 925                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 926                                 let mut message_recipients = self.message_recipients.lock().unwrap();
 927                                 if outbound_buffer_full(&next_node_id, &message_recipients) {
 928                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 929                                         return
 930                                 }
 931
 932                                 #[cfg(fuzzing)]
 933                                 message_recipients
 934                                         .entry(next_node_id)
 935                                         .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
 936
 937                                 match message_recipients.entry(next_node_id) {
 938                                         hash_map::Entry::Occupied(mut e) if matches!(
 939                                                 e.get(), OnionMessageRecipient::ConnectedPeer(..)
 940                                         ) => {
 941                                                 e.get_mut().enqueue_message(onion_message);
 942                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 943                                         },
 944                                         _ => {
 945                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 946                                                 return
 947                                         },
 948                                 }
 949                         },
 950                         Err(e) => {
 951                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
 952                         }
 953                 }
 954         }
 955
 956         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 957                 if init.features.supports_onion_messages() {
 958                         self.message_recipients.lock().unwrap()
 959                                 .entry(*their_node_id)
 960                                 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
 961                                 .mark_connected();
 962                 } else {
 963                         self.message_recipients.lock().unwrap().remove(their_node_id);
 964                 }
 965
 966                 Ok(())
 967         }
 968
 969         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 970                 match self.message_recipients.lock().unwrap().remove(their_node_id) {
 971                         Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
 972                         Some(_) => debug_assert!(false),
 973                         None => {},
 974                 }
 975         }
 976
 977         fn timer_tick_occurred(&self) {
 978                 let mut message_recipients = self.message_recipients.lock().unwrap();
 979
 980                 // Drop any pending recipients since the last call to avoid retaining buffered messages for
 981                 // too long.
 982                 message_recipients.retain(|_, recipient| match recipient {
 983                         OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
 984                         OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
 985                         _ => true,
 986                 });
 987
 988                 // Increment a timer tick for pending recipients so that their buffered messages are dropped
 989                 // at MAX_TIMER_TICKS.
 990                 for recipient in message_recipients.values_mut() {
 991                         if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
 992                                 *ticks += 1;
 993                         }
 994                 }
 995         }
 996
 997         fn provided_node_features(&self) -> NodeFeatures {
 998                 let mut features = NodeFeatures::empty();
 999                 features.set_onion_messages_optional();
1000                 features
1001         }
1002
1003         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1004                 let mut features = InitFeatures::empty();
1005                 features.set_onion_messages_optional();
1006                 features
1007         }
1008
1009         // Before returning any messages to send for the peer, this method will see if any messages were
1010         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1011         // node, and then enqueue the message for sending to the first peer in the full path.
1012         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1013                 // Enqueue any initiating `OffersMessage`s to send.
1014                 for message in self.offers_handler.release_pending_messages() {
1015                         #[cfg(not(c_bindings))]
1016                         let PendingOnionMessage { contents, destination, reply_path } = message;
1017                         #[cfg(c_bindings)]
1018                         let (contents, destination, reply_path) = message;
1019                         let _ = self.find_path_and_enqueue_onion_message(
1020                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
1021                         );
1022                 }
1023
1024                 // Enqueue any initiating `CustomMessage`s to send.
1025                 for message in self.custom_handler.release_pending_custom_messages() {
1026                         #[cfg(not(c_bindings))]
1027                         let PendingOnionMessage { contents, destination, reply_path } = message;
1028                         #[cfg(c_bindings)]
1029                         let (contents, destination, reply_path) = message;
1030                         let _ = self.find_path_and_enqueue_onion_message(
1031                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
1032                         );
1033                 }
1034
1035                 self.message_recipients.lock().unwrap()
1036                         .get_mut(&peer_node_id)
1037                         .and_then(|buffer| buffer.dequeue_message())
1038         }
1039 }
1040
1041 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1042 // produces
1043 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1044 /// [`SimpleArcPeerManager`]. See their docs for more details.
1045 ///
1046 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1047 ///
1048 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1049 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1050 #[cfg(not(c_bindings))]
1051 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1052         Arc<KeysManager>,
1053         Arc<KeysManager>,
1054         Arc<L>,
1055         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>>>,
1056         Arc<SimpleArcChannelManager<M, T, F, L>>,
1057         IgnoringMessageHandler
1058 >;
1059
1060 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1061 /// [`SimpleRefPeerManager`]. See their docs for more details.
1062 ///
1063 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1064 ///
1065 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1066 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1067 #[cfg(not(c_bindings))]
1068 pub type SimpleRefOnionMessenger<
1069         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1070 > = OnionMessenger<
1071         &'a KeysManager,
1072         &'a KeysManager,
1073         &'b L,
1074         &'i DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L>,
1075         &'j SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1076         IgnoringMessageHandler
1077 >;
1078
1079 /// Construct onion packet payloads and keys for sending an onion message along the given
1080 /// `unblinded_path` to the given `destination`.
1081 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1082         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1083         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1084 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
1085         let num_hops = unblinded_path.len() + destination.num_hops();
1086         let mut payloads = Vec::with_capacity(num_hops);
1087         let mut onion_packet_keys = Vec::with_capacity(num_hops);
1088
1089         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
1090                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
1091                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
1092         let num_unblinded_hops = num_hops - num_blinded_hops;
1093
1094         let mut unblinded_path_idx = 0;
1095         let mut blinded_path_idx = 0;
1096         let mut prev_control_tlvs_ss = None;
1097         let mut final_control_tlvs = None;
1098         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1099                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1100                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1101                                 if let Some(ss) = prev_control_tlvs_ss.take() {
1102                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1103                                                 ForwardTlvs {
1104                                                         next_node_id: unblinded_pk_opt.unwrap(),
1105                                                         next_blinding_override: None,
1106                                                 }
1107                                         )), ss));
1108                                 }
1109                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1110                                 unblinded_path_idx += 1;
1111                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1112                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1113                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1114                                                 next_node_id: intro_node_id,
1115                                                 next_blinding_override: Some(blinding_pt),
1116                                         })), control_tlvs_ss));
1117                                 }
1118                         }
1119                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1120                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1121                                         control_tlvs_ss));
1122                                 blinded_path_idx += 1;
1123                         } else if let Some(encrypted_payload) = enc_payload_opt {
1124                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1125                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1126                         }
1127
1128                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1129                         onion_packet_keys.push(onion_utils::OnionKeys {
1130                                 #[cfg(test)]
1131                                 shared_secret: onion_packet_ss,
1132                                 #[cfg(test)]
1133                                 blinding_factor: [0; 32],
1134                                 ephemeral_pubkey,
1135                                 rho,
1136                                 mu,
1137                         });
1138                 }
1139         )?;
1140
1141         if let Some(control_tlvs) = final_control_tlvs {
1142                 payloads.push((Payload::Receive {
1143                         control_tlvs,
1144                         reply_path: reply_path.take(),
1145                         message,
1146                 }, prev_control_tlvs_ss.unwrap()));
1147         } else {
1148                 payloads.push((Payload::Receive {
1149                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1150                         reply_path: reply_path.take(),
1151                         message,
1152                 }, prev_control_tlvs_ss.unwrap()));
1153         }
1154
1155         Ok((payloads, onion_packet_keys))
1156 }
1157
1158 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1159 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, ()> {
1160         // Spec rationale:
1161         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1162         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1163         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1164         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1165         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1166                 SMALL_PACKET_HOP_DATA_LEN
1167         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1168                 BIG_PACKET_HOP_DATA_LEN
1169         } else { return Err(()) };
1170
1171         onion_utils::construct_onion_message_packet::<_, _>(
1172                 payloads, onion_keys, prng_seed, hop_data_len)
1173 }