_ 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, IntroductionNode};
  19 use crate::blinded_path::message::{advance_path_by_one, ForwardTlvs, NextHop, 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, ReadOnlyNetworkGraph};
  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, WithContext};
  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>, mut destination: Destination
 322         ) -> Result<OnionMessagePath, ()> {
 323                 let network_graph = self.network_graph.deref().read_only();
 324                 destination.resolve(&network_graph);
 325
 326                 let first_node = match destination.first_node() {
 327                         Some(first_node) => first_node,
 328                         None => return Err(()),
 329                 };
 330
 331                 if peers.contains(&first_node) || sender == first_node {
 332                         Ok(OnionMessagePath {
 333                                 intermediate_nodes: vec![], destination, first_node_addresses: None
 334                         })
 335                 } else {
 336                         let node_announcement = network_graph
 337                                 .node(&NodeId::from_pubkey(&first_node))
 338                                 .and_then(|node_info| node_info.announcement_info.as_ref())
 339                                 .and_then(|announcement_info| announcement_info.announcement_message.as_ref())
 340                                 .map(|node_announcement| &node_announcement.contents);
 341
 342                         match node_announcement {
 343                                 Some(node_announcement) if node_announcement.features.supports_onion_messages() => {
 344                                         let first_node_addresses = Some(node_announcement.addresses.clone());
 345                                         Ok(OnionMessagePath {
 346                                                 intermediate_nodes: vec![], destination, first_node_addresses
 347                                         })
 348                                 },
 349                                 _ => Err(()),
 350                         }
 351                 }
 352         }
 353
 354         fn create_blinded_paths<
 355                 T: secp256k1::Signing + secp256k1::Verification
 356         >(
 357                 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 358         ) -> Result<Vec<BlindedPath>, ()> {
 359                 // Limit the number of blinded paths that are computed.
 360                 const MAX_PATHS: usize = 3;
 361
 362                 // Ensure peers have at least three channels so that it is more difficult to infer the
 363                 // recipient's node_id.
 364                 const MIN_PEER_CHANNELS: usize = 3;
 365
 366                 let network_graph = self.network_graph.deref().read_only();
 367                 let is_recipient_announced =
 368                         network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient));
 369
 370                 let mut peer_info = peers.iter()
 371                         // Limit to peers with announced channels
 372                         .filter_map(|pubkey|
 373                                 network_graph
 374                                         .node(&NodeId::from_pubkey(pubkey))
 375                                         .filter(|info| info.channels.len() >= MIN_PEER_CHANNELS)
 376                                         .map(|info| (*pubkey, info.is_tor_only(), info.channels.len()))
 377                         )
 378                         // Exclude Tor-only nodes when the recipient is announced.
 379                         .filter(|(_, is_tor_only, _)| !(*is_tor_only && is_recipient_announced))
 380                         .collect::<Vec<_>>();
 381
 382                 // Prefer using non-Tor nodes with the most channels as the introduction node.
 383                 peer_info.sort_unstable_by(|(_, a_tor_only, a_channels), (_, b_tor_only, b_channels)| {
 384                         a_tor_only.cmp(b_tor_only).then(a_channels.cmp(b_channels).reverse())
 385                 });
 386
 387                 let paths = peer_info.into_iter()
 388                         .map(|(pubkey, _, _)| vec![pubkey, recipient])
 389                         .map(|node_pks| BlindedPath::new_for_message(&node_pks, &*self.entropy_source, secp_ctx))
 390                         .take(MAX_PATHS)
 391                         .collect::<Result<Vec<_>, _>>();
 392
 393                 match paths {
 394                         Ok(paths) if !paths.is_empty() => Ok(paths),
 395                         _ => {
 396                                 if is_recipient_announced {
 397                                         BlindedPath::one_hop_for_message(recipient, &*self.entropy_source, secp_ctx)
 398                                                 .map(|path| vec![path])
 399                                 } else {
 400                                         Err(())
 401                                 }
 402                         },
 403                 }
 404         }
 405 }
 406
 407 /// A path for sending an [`OnionMessage`].
 408 #[derive(Clone)]
 409 pub struct OnionMessagePath {
 410         /// Nodes on the path between the sender and the destination.
 411         pub intermediate_nodes: Vec<PublicKey>,
 412
 413         /// The recipient of the message.
 414         pub destination: Destination,
 415
 416         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 417         ///
 418         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 419         /// this to initiate such a connection.
 420         pub first_node_addresses: Option<Vec<SocketAddress>>,
 421 }
 422
 423 impl OnionMessagePath {
 424         /// Returns the first node in the path.
 425         pub fn first_node(&self) -> Option<PublicKey> {
 426                 self.intermediate_nodes
 427                         .first()
 428                         .copied()
 429                         .or_else(|| self.destination.first_node())
 430         }
 431 }
 432
 433 /// The destination of an onion message.
 434 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 435 pub enum Destination {
 436         /// We're sending this onion message to a node.
 437         Node(PublicKey),
 438         /// We're sending this onion message to a blinded path.
 439         BlindedPath(BlindedPath),
 440 }
 441
 442 impl Destination {
 443         /// Attempts to resolve the [`IntroductionNode::DirectedShortChannelId`] of a
 444         /// [`Destination::BlindedPath`] to a [`IntroductionNode::NodeId`], if applicable, using the
 445         /// provided [`ReadOnlyNetworkGraph`].
 446         pub fn resolve(&mut self, network_graph: &ReadOnlyNetworkGraph) {
 447                 if let Destination::BlindedPath(path) = self {
 448                         if let IntroductionNode::DirectedShortChannelId(..) = path.introduction_node {
 449                                 if let Some(pubkey) = path
 450                                         .public_introduction_node_id(network_graph)
 451                                         .and_then(|node_id| node_id.as_pubkey().ok())
 452                                 {
 453                                         path.introduction_node = IntroductionNode::NodeId(pubkey);
 454                                 }
 455                         }
 456                 }
 457         }
 458
 459         pub(super) fn num_hops(&self) -> usize {
 460                 match self {
 461                         Destination::Node(_) => 1,
 462                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 463                 }
 464         }
 465
 466         fn first_node(&self) -> Option<PublicKey> {
 467                 match self {
 468                         Destination::Node(node_id) => Some(*node_id),
 469                         Destination::BlindedPath(BlindedPath { introduction_node, .. }) => {
 470                                 match introduction_node {
 471                                         IntroductionNode::NodeId(pubkey) => Some(*pubkey),
 472                                         IntroductionNode::DirectedShortChannelId(..) => None,
 473                                 }
 474                         },
 475                 }
 476         }
 477 }
 478
 479 /// Result of successfully [sending an onion message].
 480 ///
 481 /// [sending an onion message]: OnionMessenger::send_onion_message
 482 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 483 pub enum SendSuccess {
 484         /// The message was buffered and will be sent once it is processed by
 485         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 486         Buffered,
 487         /// The message was buffered and will be sent once the node is connected as a peer and it is
 488         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 489         BufferedAwaitingConnection(PublicKey),
 490 }
 491
 492 /// Errors that may occur when [sending an onion message].
 493 ///
 494 /// [sending an onion message]: OnionMessenger::send_onion_message
 495 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 496 pub enum SendError {
 497         /// Errored computing onion message packet keys.
 498         Secp256k1(secp256k1::Error),
 499         /// Because implementations such as Eclair will drop onion messages where the message packet
 500         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 501         TooBigPacket,
 502         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 503         /// hops.
 504         TooFewBlindedHops,
 505         /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
 506         InvalidFirstHop(PublicKey),
 507         /// A path from the sender to the destination could not be found by the [`MessageRouter`].
 508         PathNotFound,
 509         /// Onion message contents must have a TLV type >= 64.
 510         InvalidMessage,
 511         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 512         BufferFull,
 513         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 514         ///
 515         /// [`NodeSigner`]: crate::sign::NodeSigner
 516         GetNodeIdFailed,
 517         /// The provided [`Destination`] has a blinded path with an unresolved introduction node. An
 518         /// attempt to resolve it in the [`MessageRouter`] when finding an [`OnionMessagePath`] likely
 519         /// failed.
 520         UnresolvedIntroductionNode,
 521         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 522         /// advance the blinded path to make the second hop the new introduction node. Either
 523         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 524         /// new blinding point, or we were attempting to send to ourselves.
 525         BlindedPathAdvanceFailed,
 526 }
 527
 528 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 529 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 530 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 531 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 532 /// message types.
 533 ///
 534 /// See [`OnionMessenger`] for example usage.
 535 ///
 536 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 537 /// [`CustomMessage`]: Self::CustomMessage
 538 pub trait CustomOnionMessageHandler {
 539         /// The message known to the handler. To support multiple message types, you may want to make this
 540         /// an enum with a variant for each supported message.
 541         type CustomMessage: OnionMessageContents;
 542
 543         /// Called with the custom message that was received, returning a response to send, if any.
 544         ///
 545         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 546         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 547
 548         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 549         /// message type is unknown.
 550         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 551
 552         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 553         ///
 554         /// Typically, this is used for messages initiating a message flow rather than in response to
 555         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 556         #[cfg(not(c_bindings))]
 557         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 558
 559         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 560         ///
 561         /// Typically, this is used for messages initiating a message flow rather than in response to
 562         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 563         #[cfg(c_bindings)]
 564         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 565 }
 566
 567 /// A processed incoming onion message, containing either a Forward (another onion message)
 568 /// or a Receive payload with decrypted contents.
 569 #[derive(Debug)]
 570 pub enum PeeledOnion<T: OnionMessageContents> {
 571         /// Forwarded onion, with the next node id and a new onion
 572         Forward(NextHop, OnionMessage),
 573         /// Received onion message, with decrypted contents, path_id, and reply path
 574         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 575 }
 576
 577 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 578 /// `path`.
 579 ///
 580 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 581 /// need to connect to the first node.
 582 pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
 583         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 584         path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 585 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 586 where
 587         ES::Target: EntropySource,
 588         NS::Target: NodeSigner,
 589 {
 590         let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
 591         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 592                 if blinded_hops.is_empty() {
 593                         return Err(SendError::TooFewBlindedHops);
 594                 }
 595         }
 596
 597         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 598
 599         // If we are sending straight to a blinded path and we are the introduction node, we need to
 600         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 601         if intermediate_nodes.len() == 0 {
 602                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 603                         let introduction_node_id = match blinded_path.introduction_node {
 604                                 IntroductionNode::NodeId(pubkey) => pubkey,
 605                                 IntroductionNode::DirectedShortChannelId(..) => {
 606                                         return Err(SendError::UnresolvedIntroductionNode);
 607                                 },
 608                         };
 609                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 610                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 611                         if introduction_node_id == our_node_id {
 612                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 613                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 614                         }
 615                 }
 616         }
 617
 618         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 619         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 620         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 621                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 622         } else {
 623                 match &destination {
 624                         Destination::Node(pk) => (*pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 625                         Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, .. }) => {
 626                                 match introduction_node {
 627                                         IntroductionNode::NodeId(pubkey) => (*pubkey, *blinding_point),
 628                                         IntroductionNode::DirectedShortChannelId(..) => {
 629                                                 return Err(SendError::UnresolvedIntroductionNode);
 630                                         },
 631                                 }
 632                         }
 633                 }
 634         };
 635         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 636                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret
 637         )?;
 638
 639         let prng_seed = entropy_source.get_secure_random_bytes();
 640         let onion_routing_packet = construct_onion_message_packet(
 641                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 642
 643         let message = OnionMessage { blinding_point, onion_routing_packet };
 644         Ok((first_node_id, message, first_node_addresses))
 645 }
 646
 647 /// Decode one layer of an incoming [`OnionMessage`].
 648 ///
 649 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 650 /// receiver.
 651 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 652         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 653         custom_handler: CMH,
 654 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 655 where
 656         NS::Target: NodeSigner,
 657         L::Target: Logger,
 658         CMH::Target: CustomOnionMessageHandler,
 659 {
 660         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 661                 Ok(ss) => ss,
 662                 Err(e) =>  {
 663                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 664                         return Err(());
 665                 }
 666         };
 667         let onion_decode_ss = {
 668                 let blinding_factor = {
 669                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 670                         hmac.input(control_tlvs_ss.as_ref());
 671                         Hmac::from_engine(hmac).to_byte_array()
 672                 };
 673                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 674                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 675                 {
 676                         Ok(ss) => ss.secret_bytes(),
 677                         Err(()) => {
 678                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 679                                 return Err(());
 680                         }
 681                 }
 682         };
 683         match onion_utils::decode_next_untagged_hop(
 684                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 685                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 686         ) {
 687                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 688                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 689                 }, None)) => {
 690                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 691                 },
 692                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 693                         next_hop, next_blinding_override
 694                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 695                         // TODO: we need to check whether `next_hop` is our node, in which case this is a dummy
 696                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 697                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 698                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 699                         // for now.
 700                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 701                                 Ok(pk) => pk,
 702                                 Err(e) => {
 703                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 704                                         return Err(())
 705                                 }
 706                         };
 707                         let outgoing_packet = Packet {
 708                                 version: 0,
 709                                 public_key: new_pubkey,
 710                                 hop_data: new_packet_bytes,
 711                                 hmac: next_hop_hmac,
 712                         };
 713                         let onion_message = OnionMessage {
 714                                 blinding_point: match next_blinding_override {
 715                                         Some(blinding_point) => blinding_point,
 716                                         None => {
 717                                                 match onion_utils::next_hop_pubkey(
 718                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 719                                                 ) {
 720                                                         Ok(bp) => bp,
 721                                                         Err(e) => {
 722                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 723                                                                 return Err(())
 724                                                         }
 725                                                 }
 726                                         }
 727                                 },
 728                                 onion_routing_packet: outgoing_packet,
 729                         };
 730
 731                         Ok(PeeledOnion::Forward(next_hop, onion_message))
 732                 },
 733                 Err(e) => {
 734                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 735                         Err(())
 736                 },
 737                 _ => {
 738                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 739                         Err(())
 740                 },
 741         }
 742 }
 743
 744 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 745 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 746 where
 747         ES::Target: EntropySource,
 748         NS::Target: NodeSigner,
 749         L::Target: Logger,
 750         MR::Target: MessageRouter,
 751         OMH::Target: OffersMessageHandler,
 752         CMH::Target: CustomOnionMessageHandler,
 753 {
 754         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 755         /// their respective handlers.
 756         pub fn new(
 757                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 758                 custom_handler: CMH
 759         ) -> Self {
 760                 let mut secp_ctx = Secp256k1::new();
 761                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 762                 OnionMessenger {
 763                         entropy_source,
 764                         node_signer,
 765                         message_recipients: Mutex::new(new_hash_map()),
 766                         secp_ctx,
 767                         logger,
 768                         message_router,
 769                         offers_handler,
 770                         custom_handler,
 771                 }
 772         }
 773
 774         #[cfg(test)]
 775         pub(crate) fn set_offers_handler(&mut self, offers_handler: OMH) {
 776                 self.offers_handler = offers_handler;
 777         }
 778
 779         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
 780         ///
 781         /// See [`OnionMessenger`] for example usage.
 782         pub fn send_onion_message<T: OnionMessageContents>(
 783                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
 784         ) -> Result<SendSuccess, SendError> {
 785                 self.find_path_and_enqueue_onion_message(
 786                         contents, destination, reply_path, format_args!("")
 787                 )
 788         }
 789
 790         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 791                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 792                 log_suffix: fmt::Arguments
 793         ) -> Result<SendSuccess, SendError> {
 794                 let mut logger = WithContext::from(&self.logger, None, None);
 795                 let result = self.find_path(destination)
 796                         .and_then(|path| {
 797                                 let first_hop = path.intermediate_nodes.get(0).map(|p| *p);
 798                                 logger = WithContext::from(&self.logger, first_hop, None);
 799                                 self.enqueue_onion_message(path, contents, reply_path, log_suffix)
 800                         });
 801
 802                 match result.as_ref() {
 803                         Err(SendError::GetNodeIdFailed) => {
 804                                 log_warn!(logger, "Unable to retrieve node id {}", log_suffix);
 805                         },
 806                         Err(SendError::PathNotFound) => {
 807                                 log_trace!(logger, "Failed to find path {}", log_suffix);
 808                         },
 809                         Err(e) => {
 810                                 log_trace!(logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 811                         },
 812                         Ok(SendSuccess::Buffered) => {
 813                                 log_trace!(logger, "Buffered onion message {}", log_suffix);
 814                         },
 815                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
 816                                 log_trace!(
 817                                         logger,
 818                                         "Buffered onion message waiting on peer connection {}: {}",
 819                                         log_suffix, node_id
 820                                 );
 821                         },
 822                 }
 823
 824                 result
 825         }
 826
 827         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
 828                 let sender = self.node_signer
 829                         .get_node_id(Recipient::Node)
 830                         .map_err(|_| SendError::GetNodeIdFailed)?;
 831
 832                 let peers = self.message_recipients.lock().unwrap()
 833                         .iter()
 834                         .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
 835                         .map(|(node_id, _)| *node_id)
 836                         .collect();
 837
 838                 self.message_router
 839                         .find_path(sender, peers, destination)
 840                         .map_err(|_| SendError::PathNotFound)
 841         }
 842
 843         fn enqueue_onion_message<T: OnionMessageContents>(
 844                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 845                 log_suffix: fmt::Arguments
 846         ) -> Result<SendSuccess, SendError> {
 847                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 848
 849                 let (first_node_id, onion_message, addresses) = create_onion_message(
 850                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
 851                 )?;
 852
 853                 let mut message_recipients = self.message_recipients.lock().unwrap();
 854                 if outbound_buffer_full(&first_node_id, &message_recipients) {
 855                         return Err(SendError::BufferFull);
 856                 }
 857
 858                 match message_recipients.entry(first_node_id) {
 859                         hash_map::Entry::Vacant(e) => match addresses {
 860                                 None => Err(SendError::InvalidFirstHop(first_node_id)),
 861                                 Some(addresses) => {
 862                                         e.insert(OnionMessageRecipient::pending_connection(addresses))
 863                                                 .enqueue_message(onion_message);
 864                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 865                                 },
 866                         },
 867                         hash_map::Entry::Occupied(mut e) => {
 868                                 e.get_mut().enqueue_message(onion_message);
 869                                 if e.get().is_connected() {
 870                                         Ok(SendSuccess::Buffered)
 871                                 } else {
 872                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 873                                 }
 874                         },
 875                 }
 876         }
 877
 878         #[cfg(any(test, feature = "_test_utils"))]
 879         pub fn send_onion_message_using_path<T: OnionMessageContents>(
 880                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
 881         ) -> Result<SendSuccess, SendError> {
 882                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
 883         }
 884
 885         pub(crate) fn peel_onion_message(
 886                 &self, msg: &OnionMessage
 887         ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()> {
 888                 peel_onion_message(
 889                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
 890                 )
 891         }
 892
 893         fn handle_onion_message_response<T: OnionMessageContents>(
 894                 &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
 895         ) {
 896                 if let Some(response) = response {
 897                         match reply_path {
 898                                 Some(reply_path) => {
 899                                         let _ = self.find_path_and_enqueue_onion_message(
 900                                                 response, Destination::BlindedPath(reply_path), None, log_suffix
 901                                         );
 902                                 },
 903                                 None => {
 904                                         log_trace!(self.logger, "Missing reply path {}", log_suffix);
 905                                 },
 906                         }
 907                 }
 908         }
 909
 910         #[cfg(test)]
 911         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 912                 let mut message_recipients = self.message_recipients.lock().unwrap();
 913                 let mut msgs = new_hash_map();
 914                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 915                 // release the pending message buffers individually.
 916                 for (node_id, recipient) in &mut *message_recipients {
 917                         msgs.insert(*node_id, recipient.release_pending_messages());
 918                 }
 919                 msgs
 920         }
 921 }
 922
 923 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
 924         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 925         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 926         let mut total_buffered_bytes = 0;
 927         let mut peer_buffered_bytes = 0;
 928         for (pk, peer_buf) in buffer {
 929                 for om in peer_buf.pending_messages() {
 930                         let om_len = om.serialized_length();
 931                         if pk == peer_node_id {
 932                                 peer_buffered_bytes += om_len;
 933                         }
 934                         total_buffered_bytes += om_len;
 935
 936                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 937                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 938                         {
 939                                 return true
 940                         }
 941                 }
 942         }
 943         false
 944 }
 945
 946 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
 947 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 948 where
 949         ES::Target: EntropySource,
 950         NS::Target: NodeSigner,
 951         L::Target: Logger,
 952         MR::Target: MessageRouter,
 953         OMH::Target: OffersMessageHandler,
 954         CMH::Target: CustomOnionMessageHandler,
 955 {
 956         fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
 957                 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
 958                         if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
 959                                 if let Some(addresses) = addresses.take() {
 960                                         handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
 961                                 }
 962                         }
 963                 }
 964         }
 965 }
 966
 967 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 968 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 969 where
 970         ES::Target: EntropySource,
 971         NS::Target: NodeSigner,
 972         L::Target: Logger,
 973         MR::Target: MessageRouter,
 974         OMH::Target: OffersMessageHandler,
 975         CMH::Target: CustomOnionMessageHandler,
 976 {
 977         fn handle_onion_message(&self, peer_node_id: &PublicKey, msg: &OnionMessage) {
 978                 let logger = WithContext::from(&self.logger, Some(*peer_node_id), None);
 979                 match self.peel_onion_message(msg) {
 980                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 981                                 log_trace!(
 982                                         logger,
 983                                         "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
 984                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
 985
 986                                 match message {
 987                                         ParsedOnionMessageContents::Offers(msg) => {
 988                                                 let response = self.offers_handler.handle_message(msg);
 989                                                 self.handle_onion_message_response(
 990                                                         response, reply_path, format_args!(
 991                                                                 "when responding to Offers onion message with path_id {:02x?}",
 992                                                                 path_id
 993                                                         )
 994                                                 );
 995                                         },
 996                                         ParsedOnionMessageContents::Custom(msg) => {
 997                                                 let response = self.custom_handler.handle_custom_message(msg);
 998                                                 self.handle_onion_message_response(
 999                                                         response, reply_path, format_args!(
1000                                                                 "when responding to Custom onion message with path_id {:02x?}",
1001                                                                 path_id
1002                                                         )
1003                                                 );
1004                                         },
1005                                 }
1006                         },
1007                         Ok(PeeledOnion::Forward(next_hop, onion_message)) => {
1008                                 let next_node_id = match next_hop {
1009                                         NextHop::NodeId(pubkey) => pubkey,
1010                                         NextHop::ShortChannelId(_) => todo!(),
1011                                 };
1012
1013                                 let mut message_recipients = self.message_recipients.lock().unwrap();
1014                                 if outbound_buffer_full(&next_node_id, &message_recipients) {
1015                                         log_trace!(
1016                                                 logger,
1017                                                 "Dropping forwarded onion message to peer {}: outbound buffer full",
1018                                                 next_node_id);
1019                                         return
1020                                 }
1021
1022                                 #[cfg(fuzzing)]
1023                                 message_recipients
1024                                         .entry(next_node_id)
1025                                         .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
1026
1027                                 match message_recipients.entry(next_node_id) {
1028                                         hash_map::Entry::Occupied(mut e) if matches!(
1029                                                 e.get(), OnionMessageRecipient::ConnectedPeer(..)
1030                                         ) => {
1031                                                 e.get_mut().enqueue_message(onion_message);
1032                                                 log_trace!(logger, "Forwarding an onion message to peer {}", next_node_id);
1033                                         },
1034                                         _ => {
1035                                                 log_trace!(
1036                                                         logger,
1037                                                         "Dropping forwarded onion message to disconnected peer {}",
1038                                                         next_node_id);
1039                                                 return
1040                                         },
1041                                 }
1042                         },
1043                         Err(e) => {
1044                                 log_error!(logger, "Failed to process onion message {:?}", e);
1045                         }
1046                 }
1047         }
1048
1049         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
1050                 if init.features.supports_onion_messages() {
1051                         self.message_recipients.lock().unwrap()
1052                                 .entry(*their_node_id)
1053                                 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
1054                                 .mark_connected();
1055                 } else {
1056                         self.message_recipients.lock().unwrap().remove(their_node_id);
1057                 }
1058
1059                 Ok(())
1060         }
1061
1062         fn peer_disconnected(&self, their_node_id: &PublicKey) {
1063                 match self.message_recipients.lock().unwrap().remove(their_node_id) {
1064                         Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
1065                         Some(_) => debug_assert!(false),
1066                         None => {},
1067                 }
1068         }
1069
1070         fn timer_tick_occurred(&self) {
1071                 let mut message_recipients = self.message_recipients.lock().unwrap();
1072
1073                 // Drop any pending recipients since the last call to avoid retaining buffered messages for
1074                 // too long.
1075                 message_recipients.retain(|_, recipient| match recipient {
1076                         OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
1077                         OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
1078                         _ => true,
1079                 });
1080
1081                 // Increment a timer tick for pending recipients so that their buffered messages are dropped
1082                 // at MAX_TIMER_TICKS.
1083                 for recipient in message_recipients.values_mut() {
1084                         if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
1085                                 *ticks += 1;
1086                         }
1087                 }
1088         }
1089
1090         fn provided_node_features(&self) -> NodeFeatures {
1091                 let mut features = NodeFeatures::empty();
1092                 features.set_onion_messages_optional();
1093                 features
1094         }
1095
1096         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1097                 let mut features = InitFeatures::empty();
1098                 features.set_onion_messages_optional();
1099                 features
1100         }
1101
1102         // Before returning any messages to send for the peer, this method will see if any messages were
1103         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1104         // node, and then enqueue the message for sending to the first peer in the full path.
1105         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1106                 // Enqueue any initiating `OffersMessage`s to send.
1107                 for message in self.offers_handler.release_pending_messages() {
1108                         #[cfg(not(c_bindings))]
1109                         let PendingOnionMessage { contents, destination, reply_path } = message;
1110                         #[cfg(c_bindings)]
1111                         let (contents, destination, reply_path) = message;
1112                         let _ = self.find_path_and_enqueue_onion_message(
1113                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
1114                         );
1115                 }
1116
1117                 // Enqueue any initiating `CustomMessage`s to send.
1118                 for message in self.custom_handler.release_pending_custom_messages() {
1119                         #[cfg(not(c_bindings))]
1120                         let PendingOnionMessage { contents, destination, reply_path } = message;
1121                         #[cfg(c_bindings)]
1122                         let (contents, destination, reply_path) = message;
1123                         let _ = self.find_path_and_enqueue_onion_message(
1124                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
1125                         );
1126                 }
1127
1128                 self.message_recipients.lock().unwrap()
1129                         .get_mut(&peer_node_id)
1130                         .and_then(|buffer| buffer.dequeue_message())
1131         }
1132 }
1133
1134 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1135 // produces
1136 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1137 /// [`SimpleArcPeerManager`]. See their docs for more details.
1138 ///
1139 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1140 ///
1141 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1142 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1143 #[cfg(not(c_bindings))]
1144 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1145         Arc<KeysManager>,
1146         Arc<KeysManager>,
1147         Arc<L>,
1148         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>, Arc<KeysManager>>>,
1149         Arc<SimpleArcChannelManager<M, T, F, L>>,
1150         IgnoringMessageHandler
1151 >;
1152
1153 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1154 /// [`SimpleRefPeerManager`]. See their docs for more details.
1155 ///
1156 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1157 ///
1158 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1159 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1160 #[cfg(not(c_bindings))]
1161 pub type SimpleRefOnionMessenger<
1162         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1163 > = OnionMessenger<
1164         &'a KeysManager,
1165         &'a KeysManager,
1166         &'b L,
1167         &'i DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L, &'a KeysManager>,
1168         &'j SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1169         IgnoringMessageHandler
1170 >;
1171
1172 /// Construct onion packet payloads and keys for sending an onion message along the given
1173 /// `unblinded_path` to the given `destination`.
1174 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1175         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1176         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1177 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), SendError> {
1178         let num_hops = unblinded_path.len() + destination.num_hops();
1179         let mut payloads = Vec::with_capacity(num_hops);
1180         let mut onion_packet_keys = Vec::with_capacity(num_hops);
1181
1182         let (mut intro_node_id_blinding_pt, num_blinded_hops) = match &destination {
1183                 Destination::Node(_) => (None, 0),
1184                 Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, blinded_hops }) => {
1185                         let introduction_node_id = match introduction_node {
1186                                 IntroductionNode::NodeId(pubkey) => pubkey,
1187                                 IntroductionNode::DirectedShortChannelId(..) => {
1188                                         return Err(SendError::UnresolvedIntroductionNode);
1189                                 },
1190                         };
1191                         (Some((*introduction_node_id, *blinding_point)), blinded_hops.len())
1192                 },
1193         };
1194         let num_unblinded_hops = num_hops - num_blinded_hops;
1195
1196         let mut unblinded_path_idx = 0;
1197         let mut blinded_path_idx = 0;
1198         let mut prev_control_tlvs_ss = None;
1199         let mut final_control_tlvs = None;
1200         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1201                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1202                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1203                                 if let Some(ss) = prev_control_tlvs_ss.take() {
1204                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1205                                                 ForwardTlvs {
1206                                                         next_hop: NextHop::NodeId(unblinded_pk_opt.unwrap()),
1207                                                         next_blinding_override: None,
1208                                                 }
1209                                         )), ss));
1210                                 }
1211                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1212                                 unblinded_path_idx += 1;
1213                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1214                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1215                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1216                                                 next_hop: NextHop::NodeId(intro_node_id),
1217                                                 next_blinding_override: Some(blinding_pt),
1218                                         })), control_tlvs_ss));
1219                                 }
1220                         }
1221                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1222                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1223                                         control_tlvs_ss));
1224                                 blinded_path_idx += 1;
1225                         } else if let Some(encrypted_payload) = enc_payload_opt {
1226                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1227                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1228                         }
1229
1230                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1231                         onion_packet_keys.push(onion_utils::OnionKeys {
1232                                 #[cfg(test)]
1233                                 shared_secret: onion_packet_ss,
1234                                 #[cfg(test)]
1235                                 blinding_factor: [0; 32],
1236                                 ephemeral_pubkey,
1237                                 rho,
1238                                 mu,
1239                         });
1240                 }
1241         ).map_err(|e| SendError::Secp256k1(e))?;
1242
1243         if let Some(control_tlvs) = final_control_tlvs {
1244                 payloads.push((Payload::Receive {
1245                         control_tlvs,
1246                         reply_path: reply_path.take(),
1247                         message,
1248                 }, prev_control_tlvs_ss.unwrap()));
1249         } else {
1250                 payloads.push((Payload::Receive {
1251                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1252                         reply_path: reply_path.take(),
1253                         message,
1254                 }, prev_control_tlvs_ss.unwrap()));
1255         }
1256
1257         Ok((payloads, onion_packet_keys))
1258 }
1259
1260 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1261 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, ()> {
1262         // Spec rationale:
1263         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1264         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1265         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1266         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1267         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1268                 SMALL_PACKET_HOP_DATA_LEN
1269         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1270                 BIG_PACKET_HOP_DATA_LEN
1271         } else { return Err(()) };
1272
1273         onion_utils::construct_onion_message_packet::<_, _>(
1274                 payloads, onion_keys, prng_seed, hop_data_len)
1275 }