_ 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 paths = peers.iter()
 362                         // Limit to peers with announced channels
 363                         .filter(|pubkey|
 364                                 network_graph
 365                                         .node(&NodeId::from_pubkey(pubkey))
 366                                         .map(|info| &info.channels[..])
 367                                         .map(|channels| channels.len() >= MIN_PEER_CHANNELS)
 368                                         .unwrap_or(false)
 369                         )
 370                         .map(|pubkey| vec![*pubkey, recipient])
 371                         .map(|node_pks| BlindedPath::new_for_message(&node_pks, &*self.entropy_source, secp_ctx))
 372                         .take(MAX_PATHS)
 373                         .collect::<Result<Vec<_>, _>>();
 374
 375                 match paths {
 376                         Ok(paths) if !paths.is_empty() => Ok(paths),
 377                         _ => {
 378                                 if network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient)) {
 379                                         BlindedPath::one_hop_for_message(recipient, &*self.entropy_source, secp_ctx)
 380                                                 .map(|path| vec![path])
 381                                 } else {
 382                                         Err(())
 383                                 }
 384                         },
 385                 }
 386         }
 387 }
 388
 389 /// A path for sending an [`OnionMessage`].
 390 #[derive(Clone)]
 391 pub struct OnionMessagePath {
 392         /// Nodes on the path between the sender and the destination.
 393         pub intermediate_nodes: Vec<PublicKey>,
 394
 395         /// The recipient of the message.
 396         pub destination: Destination,
 397
 398         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 399         ///
 400         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 401         /// this to initiate such a connection.
 402         pub first_node_addresses: Option<Vec<SocketAddress>>,
 403 }
 404
 405 impl OnionMessagePath {
 406         /// Returns the first node in the path.
 407         pub fn first_node(&self) -> PublicKey {
 408                 self.intermediate_nodes
 409                         .first()
 410                         .copied()
 411                         .unwrap_or_else(|| self.destination.first_node())
 412         }
 413 }
 414
 415 /// The destination of an onion message.
 416 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 417 pub enum Destination {
 418         /// We're sending this onion message to a node.
 419         Node(PublicKey),
 420         /// We're sending this onion message to a blinded path.
 421         BlindedPath(BlindedPath),
 422 }
 423
 424 impl Destination {
 425         pub(super) fn num_hops(&self) -> usize {
 426                 match self {
 427                         Destination::Node(_) => 1,
 428                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 429                 }
 430         }
 431
 432         fn first_node(&self) -> PublicKey {
 433                 match self {
 434                         Destination::Node(node_id) => *node_id,
 435                         Destination::BlindedPath(BlindedPath { introduction_node_id: node_id, .. }) => *node_id,
 436                 }
 437         }
 438 }
 439
 440 /// Result of successfully [sending an onion message].
 441 ///
 442 /// [sending an onion message]: OnionMessenger::send_onion_message
 443 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 444 pub enum SendSuccess {
 445         /// The message was buffered and will be sent once it is processed by
 446         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 447         Buffered,
 448         /// The message was buffered and will be sent once the node is connected as a peer and it is
 449         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 450         BufferedAwaitingConnection(PublicKey),
 451 }
 452
 453 /// Errors that may occur when [sending an onion message].
 454 ///
 455 /// [sending an onion message]: OnionMessenger::send_onion_message
 456 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 457 pub enum SendError {
 458         /// Errored computing onion message packet keys.
 459         Secp256k1(secp256k1::Error),
 460         /// Because implementations such as Eclair will drop onion messages where the message packet
 461         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 462         TooBigPacket,
 463         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 464         /// hops.
 465         TooFewBlindedHops,
 466         /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
 467         InvalidFirstHop(PublicKey),
 468         /// A path from the sender to the destination could not be found by the [`MessageRouter`].
 469         PathNotFound,
 470         /// Onion message contents must have a TLV type >= 64.
 471         InvalidMessage,
 472         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 473         BufferFull,
 474         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 475         ///
 476         /// [`NodeSigner`]: crate::sign::NodeSigner
 477         GetNodeIdFailed,
 478         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 479         /// advance the blinded path to make the second hop the new introduction node. Either
 480         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 481         /// new blinding point, or we were attempting to send to ourselves.
 482         BlindedPathAdvanceFailed,
 483 }
 484
 485 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 486 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 487 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 488 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 489 /// message types.
 490 ///
 491 /// See [`OnionMessenger`] for example usage.
 492 ///
 493 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 494 /// [`CustomMessage`]: Self::CustomMessage
 495 pub trait CustomOnionMessageHandler {
 496         /// The message known to the handler. To support multiple message types, you may want to make this
 497         /// an enum with a variant for each supported message.
 498         type CustomMessage: OnionMessageContents;
 499
 500         /// Called with the custom message that was received, returning a response to send, if any.
 501         ///
 502         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 503         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 504
 505         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 506         /// message type is unknown.
 507         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 508
 509         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 510         ///
 511         /// Typically, this is used for messages initiating a message flow rather than in response to
 512         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 513         #[cfg(not(c_bindings))]
 514         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 515
 516         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 517         ///
 518         /// Typically, this is used for messages initiating a message flow rather than in response to
 519         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 520         #[cfg(c_bindings)]
 521         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 522 }
 523
 524 /// A processed incoming onion message, containing either a Forward (another onion message)
 525 /// or a Receive payload with decrypted contents.
 526 #[derive(Debug)]
 527 pub enum PeeledOnion<T: OnionMessageContents> {
 528         /// Forwarded onion, with the next node id and a new onion
 529         Forward(PublicKey, OnionMessage),
 530         /// Received onion message, with decrypted contents, path_id, and reply path
 531         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 532 }
 533
 534 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 535 /// `path`.
 536 ///
 537 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 538 /// need to connect to the first node.
 539 pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
 540         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 541         path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 542 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 543 where
 544         ES::Target: EntropySource,
 545         NS::Target: NodeSigner,
 546 {
 547         let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
 548         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 549                 if blinded_hops.is_empty() {
 550                         return Err(SendError::TooFewBlindedHops);
 551                 }
 552         }
 553
 554         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 555
 556         // If we are sending straight to a blinded path and we are the introduction node, we need to
 557         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 558         if intermediate_nodes.len() == 0 {
 559                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 560                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 561                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 562                         if blinded_path.introduction_node_id == our_node_id {
 563                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 564                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 565                         }
 566                 }
 567         }
 568
 569         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 570         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 571         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 572                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 573         } else {
 574                 match destination {
 575                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 576                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 577                                 (introduction_node_id, blinding_point),
 578                 }
 579         };
 580         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 581                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret)
 582                 .map_err(|e| SendError::Secp256k1(e))?;
 583
 584         let prng_seed = entropy_source.get_secure_random_bytes();
 585         let onion_routing_packet = construct_onion_message_packet(
 586                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 587
 588         let message = OnionMessage { blinding_point, onion_routing_packet };
 589         Ok((first_node_id, message, first_node_addresses))
 590 }
 591
 592 /// Decode one layer of an incoming [`OnionMessage`].
 593 ///
 594 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 595 /// receiver.
 596 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 597         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 598         custom_handler: CMH,
 599 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 600 where
 601         NS::Target: NodeSigner,
 602         L::Target: Logger,
 603         CMH::Target: CustomOnionMessageHandler,
 604 {
 605         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 606                 Ok(ss) => ss,
 607                 Err(e) =>  {
 608                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 609                         return Err(());
 610                 }
 611         };
 612         let onion_decode_ss = {
 613                 let blinding_factor = {
 614                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 615                         hmac.input(control_tlvs_ss.as_ref());
 616                         Hmac::from_engine(hmac).to_byte_array()
 617                 };
 618                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 619                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 620                 {
 621                         Ok(ss) => ss.secret_bytes(),
 622                         Err(()) => {
 623                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 624                                 return Err(());
 625                         }
 626                 }
 627         };
 628         match onion_utils::decode_next_untagged_hop(
 629                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 630                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 631         ) {
 632                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 633                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 634                 }, None)) => {
 635                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 636                 },
 637                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 638                         next_node_id, next_blinding_override
 639                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 640                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 641                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 642                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 643                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 644                         // for now.
 645                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 646                                 Ok(pk) => pk,
 647                                 Err(e) => {
 648                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 649                                         return Err(())
 650                                 }
 651                         };
 652                         let outgoing_packet = Packet {
 653                                 version: 0,
 654                                 public_key: new_pubkey,
 655                                 hop_data: new_packet_bytes,
 656                                 hmac: next_hop_hmac,
 657                         };
 658                         let onion_message = OnionMessage {
 659                                 blinding_point: match next_blinding_override {
 660                                         Some(blinding_point) => blinding_point,
 661                                         None => {
 662                                                 match onion_utils::next_hop_pubkey(
 663                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 664                                                 ) {
 665                                                         Ok(bp) => bp,
 666                                                         Err(e) => {
 667                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 668                                                                 return Err(())
 669                                                         }
 670                                                 }
 671                                         }
 672                                 },
 673                                 onion_routing_packet: outgoing_packet,
 674                         };
 675
 676                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 677                 },
 678                 Err(e) => {
 679                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 680                         Err(())
 681                 },
 682                 _ => {
 683                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 684                         Err(())
 685                 },
 686         }
 687 }
 688
 689 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 690 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 691 where
 692         ES::Target: EntropySource,
 693         NS::Target: NodeSigner,
 694         L::Target: Logger,
 695         MR::Target: MessageRouter,
 696         OMH::Target: OffersMessageHandler,
 697         CMH::Target: CustomOnionMessageHandler,
 698 {
 699         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 700         /// their respective handlers.
 701         pub fn new(
 702                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 703                 custom_handler: CMH
 704         ) -> Self {
 705                 let mut secp_ctx = Secp256k1::new();
 706                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 707                 OnionMessenger {
 708                         entropy_source,
 709                         node_signer,
 710                         message_recipients: Mutex::new(new_hash_map()),
 711                         secp_ctx,
 712                         logger,
 713                         message_router,
 714                         offers_handler,
 715                         custom_handler,
 716                 }
 717         }
 718
 719         #[cfg(test)]
 720         pub(crate) fn set_offers_handler(&mut self, offers_handler: OMH) {
 721                 self.offers_handler = offers_handler;
 722         }
 723
 724         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
 725         ///
 726         /// See [`OnionMessenger`] for example usage.
 727         pub fn send_onion_message<T: OnionMessageContents>(
 728                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
 729         ) -> Result<SendSuccess, SendError> {
 730                 self.find_path_and_enqueue_onion_message(
 731                         contents, destination, reply_path, format_args!("")
 732                 )
 733         }
 734
 735         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 736                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 737                 log_suffix: fmt::Arguments
 738         ) -> Result<SendSuccess, SendError> {
 739                 let result = self.find_path(destination)
 740                         .and_then(|path| self.enqueue_onion_message(path, contents, reply_path, log_suffix));
 741
 742                 match result.as_ref() {
 743                         Err(SendError::GetNodeIdFailed) => {
 744                                 log_warn!(self.logger, "Unable to retrieve node id {}", log_suffix);
 745                         },
 746                         Err(SendError::PathNotFound) => {
 747                                 log_trace!(self.logger, "Failed to find path {}", log_suffix);
 748                         },
 749                         Err(e) => {
 750                                 log_trace!(self.logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 751                         },
 752                         Ok(SendSuccess::Buffered) => {
 753                                 log_trace!(self.logger, "Buffered onion message {}", log_suffix);
 754                         },
 755                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
 756                                 log_trace!(
 757                                         self.logger, "Buffered onion message waiting on peer connection {}: {:?}",
 758                                         log_suffix, node_id
 759                                 );
 760                         },
 761                 }
 762
 763                 result
 764         }
 765
 766         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
 767                 let sender = self.node_signer
 768                         .get_node_id(Recipient::Node)
 769                         .map_err(|_| SendError::GetNodeIdFailed)?;
 770
 771                 let peers = self.message_recipients.lock().unwrap()
 772                         .iter()
 773                         .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
 774                         .map(|(node_id, _)| *node_id)
 775                         .collect();
 776
 777                 self.message_router
 778                         .find_path(sender, peers, destination)
 779                         .map_err(|_| SendError::PathNotFound)
 780         }
 781
 782         fn enqueue_onion_message<T: OnionMessageContents>(
 783                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 784                 log_suffix: fmt::Arguments
 785         ) -> Result<SendSuccess, SendError> {
 786                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 787
 788                 let (first_node_id, onion_message, addresses) = create_onion_message(
 789                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
 790                 )?;
 791
 792                 let mut message_recipients = self.message_recipients.lock().unwrap();
 793                 if outbound_buffer_full(&first_node_id, &message_recipients) {
 794                         return Err(SendError::BufferFull);
 795                 }
 796
 797                 match message_recipients.entry(first_node_id) {
 798                         hash_map::Entry::Vacant(e) => match addresses {
 799                                 None => Err(SendError::InvalidFirstHop(first_node_id)),
 800                                 Some(addresses) => {
 801                                         e.insert(OnionMessageRecipient::pending_connection(addresses))
 802                                                 .enqueue_message(onion_message);
 803                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 804                                 },
 805                         },
 806                         hash_map::Entry::Occupied(mut e) => {
 807                                 e.get_mut().enqueue_message(onion_message);
 808                                 if e.get().is_connected() {
 809                                         Ok(SendSuccess::Buffered)
 810                                 } else {
 811                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 812                                 }
 813                         },
 814                 }
 815         }
 816
 817         #[cfg(any(test, feature = "_test_utils"))]
 818         pub fn send_onion_message_using_path<T: OnionMessageContents>(
 819                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
 820         ) -> Result<SendSuccess, SendError> {
 821                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
 822         }
 823
 824         pub(crate) fn peel_onion_message(
 825                 &self, msg: &OnionMessage
 826         ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()> {
 827                 peel_onion_message(
 828                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
 829                 )
 830         }
 831
 832         fn handle_onion_message_response<T: OnionMessageContents>(
 833                 &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
 834         ) {
 835                 if let Some(response) = response {
 836                         match reply_path {
 837                                 Some(reply_path) => {
 838                                         let _ = self.find_path_and_enqueue_onion_message(
 839                                                 response, Destination::BlindedPath(reply_path), None, log_suffix
 840                                         );
 841                                 },
 842                                 None => {
 843                                         log_trace!(self.logger, "Missing reply path {}", log_suffix);
 844                                 },
 845                         }
 846                 }
 847         }
 848
 849         #[cfg(test)]
 850         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 851                 let mut message_recipients = self.message_recipients.lock().unwrap();
 852                 let mut msgs = new_hash_map();
 853                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 854                 // release the pending message buffers individually.
 855                 for (node_id, recipient) in &mut *message_recipients {
 856                         msgs.insert(*node_id, recipient.release_pending_messages());
 857                 }
 858                 msgs
 859         }
 860 }
 861
 862 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
 863         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 864         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 865         let mut total_buffered_bytes = 0;
 866         let mut peer_buffered_bytes = 0;
 867         for (pk, peer_buf) in buffer {
 868                 for om in peer_buf.pending_messages() {
 869                         let om_len = om.serialized_length();
 870                         if pk == peer_node_id {
 871                                 peer_buffered_bytes += om_len;
 872                         }
 873                         total_buffered_bytes += om_len;
 874
 875                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 876                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 877                         {
 878                                 return true
 879                         }
 880                 }
 881         }
 882         false
 883 }
 884
 885 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
 886 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 887 where
 888         ES::Target: EntropySource,
 889         NS::Target: NodeSigner,
 890         L::Target: Logger,
 891         MR::Target: MessageRouter,
 892         OMH::Target: OffersMessageHandler,
 893         CMH::Target: CustomOnionMessageHandler,
 894 {
 895         fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
 896                 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
 897                         if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
 898                                 if let Some(addresses) = addresses.take() {
 899                                         handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
 900                                 }
 901                         }
 902                 }
 903         }
 904 }
 905
 906 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 907 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 908 where
 909         ES::Target: EntropySource,
 910         NS::Target: NodeSigner,
 911         L::Target: Logger,
 912         MR::Target: MessageRouter,
 913         OMH::Target: OffersMessageHandler,
 914         CMH::Target: CustomOnionMessageHandler,
 915 {
 916         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
 917                 match self.peel_onion_message(msg) {
 918                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 919                                 log_trace!(
 920                                         self.logger,
 921                                    "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
 922                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
 923
 924                                 match message {
 925                                         ParsedOnionMessageContents::Offers(msg) => {
 926                                                 let response = self.offers_handler.handle_message(msg);
 927                                                 self.handle_onion_message_response(
 928                                                         response, reply_path, format_args!(
 929                                                                 "when responding to Offers onion message with path_id {:02x?}",
 930                                                                 path_id
 931                                                         )
 932                                                 );
 933                                         },
 934                                         ParsedOnionMessageContents::Custom(msg) => {
 935                                                 let response = self.custom_handler.handle_custom_message(msg);
 936                                                 self.handle_onion_message_response(
 937                                                         response, reply_path, format_args!(
 938                                                                 "when responding to Custom onion message with path_id {:02x?}",
 939                                                                 path_id
 940                                                         )
 941                                                 );
 942                                         },
 943                                 }
 944                         },
 945                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 946                                 let mut message_recipients = self.message_recipients.lock().unwrap();
 947                                 if outbound_buffer_full(&next_node_id, &message_recipients) {
 948                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 949                                         return
 950                                 }
 951
 952                                 #[cfg(fuzzing)]
 953                                 message_recipients
 954                                         .entry(next_node_id)
 955                                         .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
 956
 957                                 match message_recipients.entry(next_node_id) {
 958                                         hash_map::Entry::Occupied(mut e) if matches!(
 959                                                 e.get(), OnionMessageRecipient::ConnectedPeer(..)
 960                                         ) => {
 961                                                 e.get_mut().enqueue_message(onion_message);
 962                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 963                                         },
 964                                         _ => {
 965                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 966                                                 return
 967                                         },
 968                                 }
 969                         },
 970                         Err(e) => {
 971                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
 972                         }
 973                 }
 974         }
 975
 976         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 977                 if init.features.supports_onion_messages() {
 978                         self.message_recipients.lock().unwrap()
 979                                 .entry(*their_node_id)
 980                                 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
 981                                 .mark_connected();
 982                 } else {
 983                         self.message_recipients.lock().unwrap().remove(their_node_id);
 984                 }
 985
 986                 Ok(())
 987         }
 988
 989         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 990                 match self.message_recipients.lock().unwrap().remove(their_node_id) {
 991                         Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
 992                         Some(_) => debug_assert!(false),
 993                         None => {},
 994                 }
 995         }
 996
 997         fn timer_tick_occurred(&self) {
 998                 let mut message_recipients = self.message_recipients.lock().unwrap();
 999
1000                 // Drop any pending recipients since the last call to avoid retaining buffered messages for
1001                 // too long.
1002                 message_recipients.retain(|_, recipient| match recipient {
1003                         OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
1004                         OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
1005                         _ => true,
1006                 });
1007
1008                 // Increment a timer tick for pending recipients so that their buffered messages are dropped
1009                 // at MAX_TIMER_TICKS.
1010                 for recipient in message_recipients.values_mut() {
1011                         if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
1012                                 *ticks += 1;
1013                         }
1014                 }
1015         }
1016
1017         fn provided_node_features(&self) -> NodeFeatures {
1018                 let mut features = NodeFeatures::empty();
1019                 features.set_onion_messages_optional();
1020                 features
1021         }
1022
1023         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1024                 let mut features = InitFeatures::empty();
1025                 features.set_onion_messages_optional();
1026                 features
1027         }
1028
1029         // Before returning any messages to send for the peer, this method will see if any messages were
1030         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1031         // node, and then enqueue the message for sending to the first peer in the full path.
1032         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1033                 // Enqueue any initiating `OffersMessage`s to send.
1034                 for message in self.offers_handler.release_pending_messages() {
1035                         #[cfg(not(c_bindings))]
1036                         let PendingOnionMessage { contents, destination, reply_path } = message;
1037                         #[cfg(c_bindings)]
1038                         let (contents, destination, reply_path) = message;
1039                         let _ = self.find_path_and_enqueue_onion_message(
1040                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
1041                         );
1042                 }
1043
1044                 // Enqueue any initiating `CustomMessage`s to send.
1045                 for message in self.custom_handler.release_pending_custom_messages() {
1046                         #[cfg(not(c_bindings))]
1047                         let PendingOnionMessage { contents, destination, reply_path } = message;
1048                         #[cfg(c_bindings)]
1049                         let (contents, destination, reply_path) = message;
1050                         let _ = self.find_path_and_enqueue_onion_message(
1051                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
1052                         );
1053                 }
1054
1055                 self.message_recipients.lock().unwrap()
1056                         .get_mut(&peer_node_id)
1057                         .and_then(|buffer| buffer.dequeue_message())
1058         }
1059 }
1060
1061 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1062 // produces
1063 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1064 /// [`SimpleArcPeerManager`]. See their docs for more details.
1065 ///
1066 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1067 ///
1068 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1069 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1070 #[cfg(not(c_bindings))]
1071 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1072         Arc<KeysManager>,
1073         Arc<KeysManager>,
1074         Arc<L>,
1075         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>, Arc<KeysManager>>>,
1076         Arc<SimpleArcChannelManager<M, T, F, L>>,
1077         IgnoringMessageHandler
1078 >;
1079
1080 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1081 /// [`SimpleRefPeerManager`]. See their docs for more details.
1082 ///
1083 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1084 ///
1085 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1086 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1087 #[cfg(not(c_bindings))]
1088 pub type SimpleRefOnionMessenger<
1089         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1090 > = OnionMessenger<
1091         &'a KeysManager,
1092         &'a KeysManager,
1093         &'b L,
1094         &'i DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L, &'a KeysManager>,
1095         &'j SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1096         IgnoringMessageHandler
1097 >;
1098
1099 /// Construct onion packet payloads and keys for sending an onion message along the given
1100 /// `unblinded_path` to the given `destination`.
1101 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1102         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1103         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1104 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
1105         let num_hops = unblinded_path.len() + destination.num_hops();
1106         let mut payloads = Vec::with_capacity(num_hops);
1107         let mut onion_packet_keys = Vec::with_capacity(num_hops);
1108
1109         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
1110                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
1111                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
1112         let num_unblinded_hops = num_hops - num_blinded_hops;
1113
1114         let mut unblinded_path_idx = 0;
1115         let mut blinded_path_idx = 0;
1116         let mut prev_control_tlvs_ss = None;
1117         let mut final_control_tlvs = None;
1118         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1119                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1120                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1121                                 if let Some(ss) = prev_control_tlvs_ss.take() {
1122                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1123                                                 ForwardTlvs {
1124                                                         next_node_id: unblinded_pk_opt.unwrap(),
1125                                                         next_blinding_override: None,
1126                                                 }
1127                                         )), ss));
1128                                 }
1129                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1130                                 unblinded_path_idx += 1;
1131                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1132                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1133                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1134                                                 next_node_id: intro_node_id,
1135                                                 next_blinding_override: Some(blinding_pt),
1136                                         })), control_tlvs_ss));
1137                                 }
1138                         }
1139                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1140                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1141                                         control_tlvs_ss));
1142                                 blinded_path_idx += 1;
1143                         } else if let Some(encrypted_payload) = enc_payload_opt {
1144                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1145                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1146                         }
1147
1148                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1149                         onion_packet_keys.push(onion_utils::OnionKeys {
1150                                 #[cfg(test)]
1151                                 shared_secret: onion_packet_ss,
1152                                 #[cfg(test)]
1153                                 blinding_factor: [0; 32],
1154                                 ephemeral_pubkey,
1155                                 rho,
1156                                 mu,
1157                         });
1158                 }
1159         )?;
1160
1161         if let Some(control_tlvs) = final_control_tlvs {
1162                 payloads.push((Payload::Receive {
1163                         control_tlvs,
1164                         reply_path: reply_path.take(),
1165                         message,
1166                 }, prev_control_tlvs_ss.unwrap()));
1167         } else {
1168                 payloads.push((Payload::Receive {
1169                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1170                         reply_path: reply_path.take(),
1171                         message,
1172                 }, prev_control_tlvs_ss.unwrap()));
1173         }
1174
1175         Ok((payloads, onion_packet_keys))
1176 }
1177
1178 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1179 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, ()> {
1180         // Spec rationale:
1181         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1182         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1183         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1184         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1185         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1186                 SMALL_PACKET_HOP_DATA_LEN
1187         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1188                 BIG_PACKET_HOP_DATA_LEN
1189         } else { return Err(()) };
1190
1191         onion_utils::construct_onion_message_packet::<_, _>(
1192                 payloads, onion_keys, prng_seed, hop_data_len)
1193 }