_ 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 use crate::ln::features::{InitFeatures, NodeFeatures};
  24 use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler, SocketAddress};
  25 use crate::ln::onion_utils;
  26 use crate::routing::gossip::{NetworkGraph, NodeId};
  27 use super::packet::OnionMessageContents;
  28 use super::packet::ParsedOnionMessageContents;
  29 use super::offers::OffersMessageHandler;
  30 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  31 use crate::util::logger::Logger;
  32 use crate::util::ser::Writeable;
  33
  34 use core::fmt;
  35 use core::ops::Deref;
  36 use crate::io;
  37 use crate::sync::Mutex;
  38 use crate::prelude::*;
  39
  40 #[cfg(not(c_bindings))]
  41 use {
  42         crate::sign::KeysManager,
  43         crate::ln::channelmanager::{SimpleArcChannelManager, SimpleRefChannelManager},
  44         crate::ln::peer_handler::IgnoringMessageHandler,
  45         crate::sync::Arc,
  46 };
  47
  48 pub(super) const MAX_TIMER_TICKS: usize = 2;
  49
  50 /// A sender, receiver and forwarder of [`OnionMessage`]s.
  51 ///
  52 /// # Handling Messages
  53 ///
  54 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
  55 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
  56 /// available handlers are:
  57 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
  58 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
  59 ///
  60 /// # Sending Messages
  61 ///
  62 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
  63 /// a message, the matched handler may return a response message which `OnionMessenger` will send
  64 /// on its behalf.
  65 ///
  66 /// # Example
  67 ///
  68 /// ```
  69 /// # extern crate bitcoin;
  70 /// # use bitcoin::hashes::_export::_core::time::Duration;
  71 /// # use bitcoin::hashes::hex::FromHex;
  72 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey, self};
  73 /// # use lightning::blinded_path::BlindedPath;
  74 /// # use lightning::sign::{EntropySource, KeysManager};
  75 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  76 /// # use lightning::onion_message::messenger::{Destination, MessageRouter, OnionMessagePath, OnionMessenger};
  77 /// # use lightning::onion_message::packet::OnionMessageContents;
  78 /// # use lightning::util::logger::{Logger, Record};
  79 /// # use lightning::util::ser::{Writeable, Writer};
  80 /// # use lightning::io;
  81 /// # use std::sync::Arc;
  82 /// # struct FakeLogger;
  83 /// # impl Logger for FakeLogger {
  84 /// #     fn log(&self, record: Record) { println!("{:?}" , record); }
  85 /// # }
  86 /// # struct FakeMessageRouter {}
  87 /// # impl MessageRouter for FakeMessageRouter {
  88 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  89 /// #         let secp_ctx = Secp256k1::new();
  90 /// #         let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  91 /// #         let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  92 /// #         let hop_node_id2 = hop_node_id1;
  93 /// #         Ok(OnionMessagePath {
  94 /// #             intermediate_nodes: vec![hop_node_id1, hop_node_id2],
  95 /// #             destination,
  96 /// #             first_node_addresses: None,
  97 /// #         })
  98 /// #     }
  99 /// #     fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
 100 /// #         &self, _recipient: PublicKey, _peers: Vec<PublicKey>, _secp_ctx: &Secp256k1<T>
 101 /// #     ) -> Result<Vec<BlindedPath>, ()> {
 102 /// #         unreachable!()
 103 /// #     }
 104 /// # }
 105 /// # let seed = [42u8; 32];
 106 /// # let time = Duration::from_secs(123456);
 107 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
 108 /// # let logger = Arc::new(FakeLogger {});
 109 /// # let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
 110 /// # let secp_ctx = Secp256k1::new();
 111 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
 112 /// # let (hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1);
 113 /// # let destination_node_id = hop_node_id1;
 114 /// # let message_router = Arc::new(FakeMessageRouter {});
 115 /// # let custom_message_handler = IgnoringMessageHandler {};
 116 /// # let offers_message_handler = IgnoringMessageHandler {};
 117 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
 118 /// // ChannelManager.
 119 /// let onion_messenger = OnionMessenger::new(
 120 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
 121 ///     &custom_message_handler
 122 /// );
 123
 124 /// # #[derive(Debug)]
 125 /// # struct YourCustomMessage {}
 126 /// impl Writeable for YourCustomMessage {
 127 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 128 ///             # Ok(())
 129 ///             // Write your custom onion message to `w`
 130 ///     }
 131 /// }
 132 /// impl OnionMessageContents for YourCustomMessage {
 133 ///     fn tlv_type(&self) -> u64 {
 134 ///             # let your_custom_message_type = 42;
 135 ///             your_custom_message_type
 136 ///     }
 137 /// }
 138 /// // Send a custom onion message to a node id.
 139 /// let destination = Destination::Node(destination_node_id);
 140 /// let reply_path = None;
 141 /// # let message = YourCustomMessage {};
 142 /// onion_messenger.send_onion_message(message, destination, reply_path);
 143 ///
 144 /// // Create a blinded path to yourself, for someone to send an onion message to.
 145 /// # let your_node_id = hop_node_id1;
 146 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 147 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 148 ///
 149 /// // Send a custom onion message to a blinded path.
 150 /// let destination = Destination::BlindedPath(blinded_path);
 151 /// let reply_path = None;
 152 /// # let message = YourCustomMessage {};
 153 /// onion_messenger.send_onion_message(message, destination, reply_path);
 154 /// ```
 155 ///
 156 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 157 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 158 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 159 where
 160         ES::Target: EntropySource,
 161         NS::Target: NodeSigner,
 162         L::Target: Logger,
 163         MR::Target: MessageRouter,
 164         OMH::Target: OffersMessageHandler,
 165         CMH::Target: CustomOnionMessageHandler,
 166 {
 167         entropy_source: ES,
 168         node_signer: NS,
 169         logger: L,
 170         message_recipients: Mutex<HashMap<PublicKey, OnionMessageRecipient>>,
 171         secp_ctx: Secp256k1<secp256k1::All>,
 172         message_router: MR,
 173         offers_handler: OMH,
 174         custom_handler: CMH,
 175 }
 176
 177 /// [`OnionMessage`]s buffered to be sent.
 178 enum OnionMessageRecipient {
 179         /// Messages for a node connected as a peer.
 180         ConnectedPeer(VecDeque<OnionMessage>),
 181
 182         /// Messages for a node that is not yet connected, which are dropped after [`MAX_TIMER_TICKS`]
 183         /// and tracked here.
 184         PendingConnection(VecDeque<OnionMessage>, Option<Vec<SocketAddress>>, usize),
 185 }
 186
 187 impl OnionMessageRecipient {
 188         fn pending_connection(addresses: Vec<SocketAddress>) -> Self {
 189                 Self::PendingConnection(VecDeque::new(), Some(addresses), 0)
 190         }
 191
 192         fn pending_messages(&self) -> &VecDeque<OnionMessage> {
 193                 match self {
 194                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 195                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 196                 }
 197         }
 198
 199         fn enqueue_message(&mut self, message: OnionMessage) {
 200                 let pending_messages = match self {
 201                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 202                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 203                 };
 204
 205                 pending_messages.push_back(message);
 206         }
 207
 208         fn dequeue_message(&mut self) -> Option<OnionMessage> {
 209                 let pending_messages = match self {
 210                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 211                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => {
 212                                 debug_assert!(false);
 213                                 pending_messages
 214                         },
 215                 };
 216
 217                 pending_messages.pop_front()
 218         }
 219
 220         #[cfg(test)]
 221         fn release_pending_messages(&mut self) -> VecDeque<OnionMessage> {
 222                 let pending_messages = match self {
 223                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 224                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 225                 };
 226
 227                 core::mem::take(pending_messages)
 228         }
 229
 230         fn mark_connected(&mut self) {
 231                 if let OnionMessageRecipient::PendingConnection(pending_messages, _, _) = self {
 232                         let mut new_pending_messages = VecDeque::new();
 233                         core::mem::swap(pending_messages, &mut new_pending_messages);
 234                         *self = OnionMessageRecipient::ConnectedPeer(new_pending_messages);
 235                 }
 236         }
 237
 238         fn is_connected(&self) -> bool {
 239                 match self {
 240                         OnionMessageRecipient::ConnectedPeer(..) => true,
 241                         OnionMessageRecipient::PendingConnection(..) => false,
 242                 }
 243         }
 244 }
 245
 246 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 247 ///
 248 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 249 /// enqueued for sending.
 250 #[cfg(not(c_bindings))]
 251 pub struct PendingOnionMessage<T: OnionMessageContents> {
 252         /// The message contents to send in an [`OnionMessage`].
 253         pub contents: T,
 254
 255         /// The destination of the message.
 256         pub destination: Destination,
 257
 258         /// A reply path to include in the [`OnionMessage`] for a response.
 259         pub reply_path: Option<BlindedPath>,
 260 }
 261
 262 #[cfg(c_bindings)]
 263 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 264 ///
 265 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 266 /// enqueued for sending.
 267 pub type PendingOnionMessage<T> = (T, Destination, Option<BlindedPath>);
 268
 269 pub(crate) fn new_pending_onion_message<T: OnionMessageContents>(
 270         contents: T, destination: Destination, reply_path: Option<BlindedPath>
 271 ) -> PendingOnionMessage<T> {
 272         #[cfg(not(c_bindings))]
 273         return PendingOnionMessage { contents, destination, reply_path };
 274         #[cfg(c_bindings)]
 275         return (contents, destination, reply_path);
 276 }
 277
 278 /// A trait defining behavior for routing an [`OnionMessage`].
 279 pub trait MessageRouter {
 280         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 281         fn find_path(
 282                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 283         ) -> Result<OnionMessagePath, ()>;
 284
 285         /// Creates [`BlindedPath`]s to the `recipient` node. The nodes in `peers` are assumed to be
 286         /// direct peers with the `recipient`.
 287         fn create_blinded_paths<
 288                 T: secp256k1::Signing + secp256k1::Verification
 289         >(
 290                 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 291         ) -> Result<Vec<BlindedPath>, ()>;
 292 }
 293
 294 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
 295 pub struct DefaultMessageRouter<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref>
 296 where
 297         L::Target: Logger,
 298         ES::Target: EntropySource,
 299 {
 300         network_graph: G,
 301         entropy_source: ES,
 302 }
 303
 304 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> DefaultMessageRouter<G, L, ES>
 305 where
 306         L::Target: Logger,
 307         ES::Target: EntropySource,
 308 {
 309         /// Creates a [`DefaultMessageRouter`] using the given [`NetworkGraph`].
 310         pub fn new(network_graph: G, entropy_source: ES) -> Self {
 311                 Self { network_graph, entropy_source }
 312         }
 313 }
 314
 315 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> MessageRouter for DefaultMessageRouter<G, L, ES>
 316 where
 317         L::Target: Logger,
 318         ES::Target: EntropySource,
 319 {
 320         fn find_path(
 321                 &self, _sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 322         ) -> Result<OnionMessagePath, ()> {
 323                 let first_node = destination.first_node();
 324                 if peers.contains(&first_node) {
 325                         Ok(OnionMessagePath {
 326                                 intermediate_nodes: vec![], destination, first_node_addresses: None
 327                         })
 328                 } else {
 329                         let network_graph = self.network_graph.deref().read_only();
 330                         let node_announcement = network_graph
 331                                 .node(&NodeId::from_pubkey(&first_node))
 332                                 .and_then(|node_info| node_info.announcement_info.as_ref())
 333                                 .and_then(|announcement_info| announcement_info.announcement_message.as_ref())
 334                                 .map(|node_announcement| &node_announcement.contents);
 335
 336                         match node_announcement {
 337                                 Some(node_announcement) if node_announcement.features.supports_onion_messages() => {
 338                                         let first_node_addresses = Some(node_announcement.addresses.clone());
 339                                         Ok(OnionMessagePath {
 340                                                 intermediate_nodes: vec![], destination, first_node_addresses
 341                                         })
 342                                 },
 343                                 _ => Err(()),
 344                         }
 345                 }
 346         }
 347
 348         fn create_blinded_paths<
 349                 T: secp256k1::Signing + secp256k1::Verification
 350         >(
 351                 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 352         ) -> Result<Vec<BlindedPath>, ()> {
 353                 // Limit the number of blinded paths that are computed.
 354                 const MAX_PATHS: usize = 3;
 355
 356                 // Ensure peers have at least three channels so that it is more difficult to infer the
 357                 // recipient's node_id.
 358                 const MIN_PEER_CHANNELS: usize = 3;
 359
 360                 let network_graph = self.network_graph.deref().read_only();
 361                 let mut peer_info = peers.iter()
 362                         // Limit to peers with announced channels
 363                         .filter_map(|pubkey|
 364                                 network_graph
 365                                         .node(&NodeId::from_pubkey(pubkey))
 366                                         .filter(|info| info.channels.len() >= MIN_PEER_CHANNELS)
 367                                         .map(|info| (*pubkey, info.is_tor_only()))
 368                         )
 369                         .collect::<Vec<_>>();
 370                 peer_info.sort_unstable_by(|(_, a_tor_only), (_, b_tor_only)| a_tor_only.cmp(b_tor_only));
 371
 372                 let paths = peer_info.into_iter()
 373                         .map(|(pubkey, _)| vec![pubkey, recipient])
 374                         .map(|node_pks| BlindedPath::new_for_message(&node_pks, &*self.entropy_source, secp_ctx))
 375                         .take(MAX_PATHS)
 376                         .collect::<Result<Vec<_>, _>>();
 377
 378                 match paths {
 379                         Ok(paths) if !paths.is_empty() => Ok(paths),
 380                         _ => {
 381                                 if network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient)) {
 382                                         BlindedPath::one_hop_for_message(recipient, &*self.entropy_source, secp_ctx)
 383                                                 .map(|path| vec![path])
 384                                 } else {
 385                                         Err(())
 386                                 }
 387                         },
 388                 }
 389         }
 390 }
 391
 392 /// A path for sending an [`OnionMessage`].
 393 #[derive(Clone)]
 394 pub struct OnionMessagePath {
 395         /// Nodes on the path between the sender and the destination.
 396         pub intermediate_nodes: Vec<PublicKey>,
 397
 398         /// The recipient of the message.
 399         pub destination: Destination,
 400
 401         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 402         ///
 403         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 404         /// this to initiate such a connection.
 405         pub first_node_addresses: Option<Vec<SocketAddress>>,
 406 }
 407
 408 impl OnionMessagePath {
 409         /// Returns the first node in the path.
 410         pub fn first_node(&self) -> PublicKey {
 411                 self.intermediate_nodes
 412                         .first()
 413                         .copied()
 414                         .unwrap_or_else(|| self.destination.first_node())
 415         }
 416 }
 417
 418 /// The destination of an onion message.
 419 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 420 pub enum Destination {
 421         /// We're sending this onion message to a node.
 422         Node(PublicKey),
 423         /// We're sending this onion message to a blinded path.
 424         BlindedPath(BlindedPath),
 425 }
 426
 427 impl Destination {
 428         pub(super) fn num_hops(&self) -> usize {
 429                 match self {
 430                         Destination::Node(_) => 1,
 431                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 432                 }
 433         }
 434
 435         fn first_node(&self) -> PublicKey {
 436                 match self {
 437                         Destination::Node(node_id) => *node_id,
 438                         Destination::BlindedPath(BlindedPath { introduction_node_id: node_id, .. }) => *node_id,
 439                 }
 440         }
 441 }
 442
 443 /// Result of successfully [sending an onion message].
 444 ///
 445 /// [sending an onion message]: OnionMessenger::send_onion_message
 446 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 447 pub enum SendSuccess {
 448         /// The message was buffered and will be sent once it is processed by
 449         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 450         Buffered,
 451         /// The message was buffered and will be sent once the node is connected as a peer and it is
 452         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 453         BufferedAwaitingConnection(PublicKey),
 454 }
 455
 456 /// Errors that may occur when [sending an onion message].
 457 ///
 458 /// [sending an onion message]: OnionMessenger::send_onion_message
 459 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 460 pub enum SendError {
 461         /// Errored computing onion message packet keys.
 462         Secp256k1(secp256k1::Error),
 463         /// Because implementations such as Eclair will drop onion messages where the message packet
 464         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 465         TooBigPacket,
 466         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 467         /// hops.
 468         TooFewBlindedHops,
 469         /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
 470         InvalidFirstHop(PublicKey),
 471         /// A path from the sender to the destination could not be found by the [`MessageRouter`].
 472         PathNotFound,
 473         /// Onion message contents must have a TLV type >= 64.
 474         InvalidMessage,
 475         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 476         BufferFull,
 477         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 478         ///
 479         /// [`NodeSigner`]: crate::sign::NodeSigner
 480         GetNodeIdFailed,
 481         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 482         /// advance the blinded path to make the second hop the new introduction node. Either
 483         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 484         /// new blinding point, or we were attempting to send to ourselves.
 485         BlindedPathAdvanceFailed,
 486 }
 487
 488 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 489 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 490 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 491 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 492 /// message types.
 493 ///
 494 /// See [`OnionMessenger`] for example usage.
 495 ///
 496 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 497 /// [`CustomMessage`]: Self::CustomMessage
 498 pub trait CustomOnionMessageHandler {
 499         /// The message known to the handler. To support multiple message types, you may want to make this
 500         /// an enum with a variant for each supported message.
 501         type CustomMessage: OnionMessageContents;
 502
 503         /// Called with the custom message that was received, returning a response to send, if any.
 504         ///
 505         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 506         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 507
 508         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 509         /// message type is unknown.
 510         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 511
 512         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 513         ///
 514         /// Typically, this is used for messages initiating a message flow rather than in response to
 515         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 516         #[cfg(not(c_bindings))]
 517         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 518
 519         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 520         ///
 521         /// Typically, this is used for messages initiating a message flow rather than in response to
 522         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 523         #[cfg(c_bindings)]
 524         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 525 }
 526
 527 /// A processed incoming onion message, containing either a Forward (another onion message)
 528 /// or a Receive payload with decrypted contents.
 529 #[derive(Debug)]
 530 pub enum PeeledOnion<T: OnionMessageContents> {
 531         /// Forwarded onion, with the next node id and a new onion
 532         Forward(PublicKey, OnionMessage),
 533         /// Received onion message, with decrypted contents, path_id, and reply path
 534         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 535 }
 536
 537 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 538 /// `path`.
 539 ///
 540 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 541 /// need to connect to the first node.
 542 pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
 543         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 544         path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 545 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 546 where
 547         ES::Target: EntropySource,
 548         NS::Target: NodeSigner,
 549 {
 550         let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
 551         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 552                 if blinded_hops.is_empty() {
 553                         return Err(SendError::TooFewBlindedHops);
 554                 }
 555         }
 556
 557         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 558
 559         // If we are sending straight to a blinded path and we are the introduction node, we need to
 560         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 561         if intermediate_nodes.len() == 0 {
 562                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 563                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 564                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 565                         if blinded_path.introduction_node_id == our_node_id {
 566                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 567                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 568                         }
 569                 }
 570         }
 571
 572         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 573         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 574         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 575                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 576         } else {
 577                 match destination {
 578                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 579                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 580                                 (introduction_node_id, blinding_point),
 581                 }
 582         };
 583         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 584                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret)
 585                 .map_err(|e| SendError::Secp256k1(e))?;
 586
 587         let prng_seed = entropy_source.get_secure_random_bytes();
 588         let onion_routing_packet = construct_onion_message_packet(
 589                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 590
 591         let message = OnionMessage { blinding_point, onion_routing_packet };
 592         Ok((first_node_id, message, first_node_addresses))
 593 }
 594
 595 /// Decode one layer of an incoming [`OnionMessage`].
 596 ///
 597 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 598 /// receiver.
 599 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 600         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 601         custom_handler: CMH,
 602 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 603 where
 604         NS::Target: NodeSigner,
 605         L::Target: Logger,
 606         CMH::Target: CustomOnionMessageHandler,
 607 {
 608         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 609                 Ok(ss) => ss,
 610                 Err(e) =>  {
 611                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 612                         return Err(());
 613                 }
 614         };
 615         let onion_decode_ss = {
 616                 let blinding_factor = {
 617                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 618                         hmac.input(control_tlvs_ss.as_ref());
 619                         Hmac::from_engine(hmac).to_byte_array()
 620                 };
 621                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 622                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 623                 {
 624                         Ok(ss) => ss.secret_bytes(),
 625                         Err(()) => {
 626                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 627                                 return Err(());
 628                         }
 629                 }
 630         };
 631         match onion_utils::decode_next_untagged_hop(
 632                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 633                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 634         ) {
 635                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 636                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 637                 }, None)) => {
 638                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 639                 },
 640                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 641                         next_node_id, next_blinding_override
 642                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 643                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 644                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 645                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 646                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 647                         // for now.
 648                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 649                                 Ok(pk) => pk,
 650                                 Err(e) => {
 651                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 652                                         return Err(())
 653                                 }
 654                         };
 655                         let outgoing_packet = Packet {
 656                                 version: 0,
 657                                 public_key: new_pubkey,
 658                                 hop_data: new_packet_bytes,
 659                                 hmac: next_hop_hmac,
 660                         };
 661                         let onion_message = OnionMessage {
 662                                 blinding_point: match next_blinding_override {
 663                                         Some(blinding_point) => blinding_point,
 664                                         None => {
 665                                                 match onion_utils::next_hop_pubkey(
 666                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 667                                                 ) {
 668                                                         Ok(bp) => bp,
 669                                                         Err(e) => {
 670                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 671                                                                 return Err(())
 672                                                         }
 673                                                 }
 674                                         }
 675                                 },
 676                                 onion_routing_packet: outgoing_packet,
 677                         };
 678
 679                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 680                 },
 681                 Err(e) => {
 682                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 683                         Err(())
 684                 },
 685                 _ => {
 686                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 687                         Err(())
 688                 },
 689         }
 690 }
 691
 692 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 693 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 694 where
 695         ES::Target: EntropySource,
 696         NS::Target: NodeSigner,
 697         L::Target: Logger,
 698         MR::Target: MessageRouter,
 699         OMH::Target: OffersMessageHandler,
 700         CMH::Target: CustomOnionMessageHandler,
 701 {
 702         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 703         /// their respective handlers.
 704         pub fn new(
 705                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 706                 custom_handler: CMH
 707         ) -> Self {
 708                 let mut secp_ctx = Secp256k1::new();
 709                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 710                 OnionMessenger {
 711                         entropy_source,
 712                         node_signer,
 713                         message_recipients: Mutex::new(new_hash_map()),
 714                         secp_ctx,
 715                         logger,
 716                         message_router,
 717                         offers_handler,
 718                         custom_handler,
 719                 }
 720         }
 721
 722         #[cfg(test)]
 723         pub(crate) fn set_offers_handler(&mut self, offers_handler: OMH) {
 724                 self.offers_handler = offers_handler;
 725         }
 726
 727         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
 728         ///
 729         /// See [`OnionMessenger`] for example usage.
 730         pub fn send_onion_message<T: OnionMessageContents>(
 731                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
 732         ) -> Result<SendSuccess, SendError> {
 733                 self.find_path_and_enqueue_onion_message(
 734                         contents, destination, reply_path, format_args!("")
 735                 )
 736         }
 737
 738         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 739                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 740                 log_suffix: fmt::Arguments
 741         ) -> Result<SendSuccess, SendError> {
 742                 let result = self.find_path(destination)
 743                         .and_then(|path| self.enqueue_onion_message(path, contents, reply_path, log_suffix));
 744
 745                 match result.as_ref() {
 746                         Err(SendError::GetNodeIdFailed) => {
 747                                 log_warn!(self.logger, "Unable to retrieve node id {}", log_suffix);
 748                         },
 749                         Err(SendError::PathNotFound) => {
 750                                 log_trace!(self.logger, "Failed to find path {}", log_suffix);
 751                         },
 752                         Err(e) => {
 753                                 log_trace!(self.logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 754                         },
 755                         Ok(SendSuccess::Buffered) => {
 756                                 log_trace!(self.logger, "Buffered onion message {}", log_suffix);
 757                         },
 758                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
 759                                 log_trace!(
 760                                         self.logger, "Buffered onion message waiting on peer connection {}: {:?}",
 761                                         log_suffix, node_id
 762                                 );
 763                         },
 764                 }
 765
 766                 result
 767         }
 768
 769         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
 770                 let sender = self.node_signer
 771                         .get_node_id(Recipient::Node)
 772                         .map_err(|_| SendError::GetNodeIdFailed)?;
 773
 774                 let peers = self.message_recipients.lock().unwrap()
 775                         .iter()
 776                         .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
 777                         .map(|(node_id, _)| *node_id)
 778                         .collect();
 779
 780                 self.message_router
 781                         .find_path(sender, peers, destination)
 782                         .map_err(|_| SendError::PathNotFound)
 783         }
 784
 785         fn enqueue_onion_message<T: OnionMessageContents>(
 786                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 787                 log_suffix: fmt::Arguments
 788         ) -> Result<SendSuccess, SendError> {
 789                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 790
 791                 let (first_node_id, onion_message, addresses) = create_onion_message(
 792                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
 793                 )?;
 794
 795                 let mut message_recipients = self.message_recipients.lock().unwrap();
 796                 if outbound_buffer_full(&first_node_id, &message_recipients) {
 797                         return Err(SendError::BufferFull);
 798                 }
 799
 800                 match message_recipients.entry(first_node_id) {
 801                         hash_map::Entry::Vacant(e) => match addresses {
 802                                 None => Err(SendError::InvalidFirstHop(first_node_id)),
 803                                 Some(addresses) => {
 804                                         e.insert(OnionMessageRecipient::pending_connection(addresses))
 805                                                 .enqueue_message(onion_message);
 806                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 807                                 },
 808                         },
 809                         hash_map::Entry::Occupied(mut e) => {
 810                                 e.get_mut().enqueue_message(onion_message);
 811                                 if e.get().is_connected() {
 812                                         Ok(SendSuccess::Buffered)
 813                                 } else {
 814                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 815                                 }
 816                         },
 817                 }
 818         }
 819
 820         #[cfg(any(test, feature = "_test_utils"))]
 821         pub fn send_onion_message_using_path<T: OnionMessageContents>(
 822                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
 823         ) -> Result<SendSuccess, SendError> {
 824                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
 825         }
 826
 827         pub(crate) fn peel_onion_message(
 828                 &self, msg: &OnionMessage
 829         ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()> {
 830                 peel_onion_message(
 831                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
 832                 )
 833         }
 834
 835         fn handle_onion_message_response<T: OnionMessageContents>(
 836                 &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
 837         ) {
 838                 if let Some(response) = response {
 839                         match reply_path {
 840                                 Some(reply_path) => {
 841                                         let _ = self.find_path_and_enqueue_onion_message(
 842                                                 response, Destination::BlindedPath(reply_path), None, log_suffix
 843                                         );
 844                                 },
 845                                 None => {
 846                                         log_trace!(self.logger, "Missing reply path {}", log_suffix);
 847                                 },
 848                         }
 849                 }
 850         }
 851
 852         #[cfg(test)]
 853         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 854                 let mut message_recipients = self.message_recipients.lock().unwrap();
 855                 let mut msgs = new_hash_map();
 856                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 857                 // release the pending message buffers individually.
 858                 for (node_id, recipient) in &mut *message_recipients {
 859                         msgs.insert(*node_id, recipient.release_pending_messages());
 860                 }
 861                 msgs
 862         }
 863 }
 864
 865 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
 866         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 867         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 868         let mut total_buffered_bytes = 0;
 869         let mut peer_buffered_bytes = 0;
 870         for (pk, peer_buf) in buffer {
 871                 for om in peer_buf.pending_messages() {
 872                         let om_len = om.serialized_length();
 873                         if pk == peer_node_id {
 874                                 peer_buffered_bytes += om_len;
 875                         }
 876                         total_buffered_bytes += om_len;
 877
 878                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 879                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 880                         {
 881                                 return true
 882                         }
 883                 }
 884         }
 885         false
 886 }
 887
 888 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
 889 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 890 where
 891         ES::Target: EntropySource,
 892         NS::Target: NodeSigner,
 893         L::Target: Logger,
 894         MR::Target: MessageRouter,
 895         OMH::Target: OffersMessageHandler,
 896         CMH::Target: CustomOnionMessageHandler,
 897 {
 898         fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
 899                 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
 900                         if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
 901                                 if let Some(addresses) = addresses.take() {
 902                                         handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
 903                                 }
 904                         }
 905                 }
 906         }
 907 }
 908
 909 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 910 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 911 where
 912         ES::Target: EntropySource,
 913         NS::Target: NodeSigner,
 914         L::Target: Logger,
 915         MR::Target: MessageRouter,
 916         OMH::Target: OffersMessageHandler,
 917         CMH::Target: CustomOnionMessageHandler,
 918 {
 919         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
 920                 match self.peel_onion_message(msg) {
 921                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 922                                 log_trace!(
 923                                         self.logger,
 924                                    "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
 925                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
 926
 927                                 match message {
 928                                         ParsedOnionMessageContents::Offers(msg) => {
 929                                                 let response = self.offers_handler.handle_message(msg);
 930                                                 self.handle_onion_message_response(
 931                                                         response, reply_path, format_args!(
 932                                                                 "when responding to Offers onion message with path_id {:02x?}",
 933                                                                 path_id
 934                                                         )
 935                                                 );
 936                                         },
 937                                         ParsedOnionMessageContents::Custom(msg) => {
 938                                                 let response = self.custom_handler.handle_custom_message(msg);
 939                                                 self.handle_onion_message_response(
 940                                                         response, reply_path, format_args!(
 941                                                                 "when responding to Custom onion message with path_id {:02x?}",
 942                                                                 path_id
 943                                                         )
 944                                                 );
 945                                         },
 946                                 }
 947                         },
 948                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 949                                 let mut message_recipients = self.message_recipients.lock().unwrap();
 950                                 if outbound_buffer_full(&next_node_id, &message_recipients) {
 951                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 952                                         return
 953                                 }
 954
 955                                 #[cfg(fuzzing)]
 956                                 message_recipients
 957                                         .entry(next_node_id)
 958                                         .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
 959
 960                                 match message_recipients.entry(next_node_id) {
 961                                         hash_map::Entry::Occupied(mut e) if matches!(
 962                                                 e.get(), OnionMessageRecipient::ConnectedPeer(..)
 963                                         ) => {
 964                                                 e.get_mut().enqueue_message(onion_message);
 965                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 966                                         },
 967                                         _ => {
 968                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 969                                                 return
 970                                         },
 971                                 }
 972                         },
 973                         Err(e) => {
 974                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
 975                         }
 976                 }
 977         }
 978
 979         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 980                 if init.features.supports_onion_messages() {
 981                         self.message_recipients.lock().unwrap()
 982                                 .entry(*their_node_id)
 983                                 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
 984                                 .mark_connected();
 985                 } else {
 986                         self.message_recipients.lock().unwrap().remove(their_node_id);
 987                 }
 988
 989                 Ok(())
 990         }
 991
 992         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 993                 match self.message_recipients.lock().unwrap().remove(their_node_id) {
 994                         Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
 995                         Some(_) => debug_assert!(false),
 996                         None => {},
 997                 }
 998         }
 999
1000         fn timer_tick_occurred(&self) {
1001                 let mut message_recipients = self.message_recipients.lock().unwrap();
1002
1003                 // Drop any pending recipients since the last call to avoid retaining buffered messages for
1004                 // too long.
1005                 message_recipients.retain(|_, recipient| match recipient {
1006                         OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
1007                         OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
1008                         _ => true,
1009                 });
1010
1011                 // Increment a timer tick for pending recipients so that their buffered messages are dropped
1012                 // at MAX_TIMER_TICKS.
1013                 for recipient in message_recipients.values_mut() {
1014                         if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
1015                                 *ticks += 1;
1016                         }
1017                 }
1018         }
1019
1020         fn provided_node_features(&self) -> NodeFeatures {
1021                 let mut features = NodeFeatures::empty();
1022                 features.set_onion_messages_optional();
1023                 features
1024         }
1025
1026         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1027                 let mut features = InitFeatures::empty();
1028                 features.set_onion_messages_optional();
1029                 features
1030         }
1031
1032         // Before returning any messages to send for the peer, this method will see if any messages were
1033         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1034         // node, and then enqueue the message for sending to the first peer in the full path.
1035         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1036                 // Enqueue any initiating `OffersMessage`s to send.
1037                 for message in self.offers_handler.release_pending_messages() {
1038                         #[cfg(not(c_bindings))]
1039                         let PendingOnionMessage { contents, destination, reply_path } = message;
1040                         #[cfg(c_bindings)]
1041                         let (contents, destination, reply_path) = message;
1042                         let _ = self.find_path_and_enqueue_onion_message(
1043                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
1044                         );
1045                 }
1046
1047                 // Enqueue any initiating `CustomMessage`s to send.
1048                 for message in self.custom_handler.release_pending_custom_messages() {
1049                         #[cfg(not(c_bindings))]
1050                         let PendingOnionMessage { contents, destination, reply_path } = message;
1051                         #[cfg(c_bindings)]
1052                         let (contents, destination, reply_path) = message;
1053                         let _ = self.find_path_and_enqueue_onion_message(
1054                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
1055                         );
1056                 }
1057
1058                 self.message_recipients.lock().unwrap()
1059                         .get_mut(&peer_node_id)
1060                         .and_then(|buffer| buffer.dequeue_message())
1061         }
1062 }
1063
1064 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1065 // produces
1066 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1067 /// [`SimpleArcPeerManager`]. See their docs for more details.
1068 ///
1069 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1070 ///
1071 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1072 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1073 #[cfg(not(c_bindings))]
1074 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1075         Arc<KeysManager>,
1076         Arc<KeysManager>,
1077         Arc<L>,
1078         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>, Arc<KeysManager>>>,
1079         Arc<SimpleArcChannelManager<M, T, F, L>>,
1080         IgnoringMessageHandler
1081 >;
1082
1083 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1084 /// [`SimpleRefPeerManager`]. See their docs for more details.
1085 ///
1086 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1087 ///
1088 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1089 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1090 #[cfg(not(c_bindings))]
1091 pub type SimpleRefOnionMessenger<
1092         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1093 > = OnionMessenger<
1094         &'a KeysManager,
1095         &'a KeysManager,
1096         &'b L,
1097         &'i DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L, &'a KeysManager>,
1098         &'j SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1099         IgnoringMessageHandler
1100 >;
1101
1102 /// Construct onion packet payloads and keys for sending an onion message along the given
1103 /// `unblinded_path` to the given `destination`.
1104 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1105         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1106         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1107 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
1108         let num_hops = unblinded_path.len() + destination.num_hops();
1109         let mut payloads = Vec::with_capacity(num_hops);
1110         let mut onion_packet_keys = Vec::with_capacity(num_hops);
1111
1112         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
1113                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
1114                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
1115         let num_unblinded_hops = num_hops - num_blinded_hops;
1116
1117         let mut unblinded_path_idx = 0;
1118         let mut blinded_path_idx = 0;
1119         let mut prev_control_tlvs_ss = None;
1120         let mut final_control_tlvs = None;
1121         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1122                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1123                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1124                                 if let Some(ss) = prev_control_tlvs_ss.take() {
1125                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1126                                                 ForwardTlvs {
1127                                                         next_node_id: unblinded_pk_opt.unwrap(),
1128                                                         next_blinding_override: None,
1129                                                 }
1130                                         )), ss));
1131                                 }
1132                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1133                                 unblinded_path_idx += 1;
1134                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1135                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1136                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1137                                                 next_node_id: intro_node_id,
1138                                                 next_blinding_override: Some(blinding_pt),
1139                                         })), control_tlvs_ss));
1140                                 }
1141                         }
1142                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1143                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1144                                         control_tlvs_ss));
1145                                 blinded_path_idx += 1;
1146                         } else if let Some(encrypted_payload) = enc_payload_opt {
1147                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1148                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1149                         }
1150
1151                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1152                         onion_packet_keys.push(onion_utils::OnionKeys {
1153                                 #[cfg(test)]
1154                                 shared_secret: onion_packet_ss,
1155                                 #[cfg(test)]
1156                                 blinding_factor: [0; 32],
1157                                 ephemeral_pubkey,
1158                                 rho,
1159                                 mu,
1160                         });
1161                 }
1162         )?;
1163
1164         if let Some(control_tlvs) = final_control_tlvs {
1165                 payloads.push((Payload::Receive {
1166                         control_tlvs,
1167                         reply_path: reply_path.take(),
1168                         message,
1169                 }, prev_control_tlvs_ss.unwrap()));
1170         } else {
1171                 payloads.push((Payload::Receive {
1172                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1173                         reply_path: reply_path.take(),
1174                         message,
1175                 }, prev_control_tlvs_ss.unwrap()));
1176         }
1177
1178         Ok((payloads, onion_packet_keys))
1179 }
1180
1181 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1182 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, ()> {
1183         // Spec rationale:
1184         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1185         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1186         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1187         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1188         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1189                 SMALL_PACKET_HOP_DATA_LEN
1190         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1191                 BIG_PACKET_HOP_DATA_LEN
1192         } else { return Err(()) };
1193
1194         onion_utils::construct_onion_message_packet::<_, _>(
1195                 payloads, onion_keys, prng_seed, hop_data_len)
1196 }