_ 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, NodeIdLookUp};
  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, EmptyNodeIdLookUp};
  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 node_id_lookup = EmptyNodeIdLookUp {};
 115 /// # let message_router = Arc::new(FakeMessageRouter {});
 116 /// # let custom_message_handler = IgnoringMessageHandler {};
 117 /// # let offers_message_handler = IgnoringMessageHandler {};
 118 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
 119 /// // ChannelManager.
 120 /// let onion_messenger = OnionMessenger::new(
 121 ///     &keys_manager, &keys_manager, logger, &node_id_lookup, message_router,
 122 ///     &offers_message_handler, &custom_message_handler
 123 /// );
 124
 125 /// # #[derive(Debug)]
 126 /// # struct YourCustomMessage {}
 127 /// impl Writeable for YourCustomMessage {
 128 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 129 ///             # Ok(())
 130 ///             // Write your custom onion message to `w`
 131 ///     }
 132 /// }
 133 /// impl OnionMessageContents for YourCustomMessage {
 134 ///     fn tlv_type(&self) -> u64 {
 135 ///             # let your_custom_message_type = 42;
 136 ///             your_custom_message_type
 137 ///     }
 138 /// }
 139 /// // Send a custom onion message to a node id.
 140 /// let destination = Destination::Node(destination_node_id);
 141 /// let reply_path = None;
 142 /// # let message = YourCustomMessage {};
 143 /// onion_messenger.send_onion_message(message, destination, reply_path);
 144 ///
 145 /// // Create a blinded path to yourself, for someone to send an onion message to.
 146 /// # let your_node_id = hop_node_id1;
 147 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 148 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 149 ///
 150 /// // Send a custom onion message to a blinded path.
 151 /// let destination = Destination::BlindedPath(blinded_path);
 152 /// let reply_path = None;
 153 /// # let message = YourCustomMessage {};
 154 /// onion_messenger.send_onion_message(message, destination, reply_path);
 155 /// ```
 156 ///
 157 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 158 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 159 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 160 where
 161         ES::Target: EntropySource,
 162         NS::Target: NodeSigner,
 163         L::Target: Logger,
 164         NL::Target: NodeIdLookUp,
 165         MR::Target: MessageRouter,
 166         OMH::Target: OffersMessageHandler,
 167         CMH::Target: CustomOnionMessageHandler,
 168 {
 169         entropy_source: ES,
 170         node_signer: NS,
 171         logger: L,
 172         message_recipients: Mutex<HashMap<PublicKey, OnionMessageRecipient>>,
 173         secp_ctx: Secp256k1<secp256k1::All>,
 174         node_id_lookup: NL,
 175         message_router: MR,
 176         offers_handler: OMH,
 177         custom_handler: CMH,
 178 }
 179
 180 /// [`OnionMessage`]s buffered to be sent.
 181 enum OnionMessageRecipient {
 182         /// Messages for a node connected as a peer.
 183         ConnectedPeer(VecDeque<OnionMessage>),
 184
 185         /// Messages for a node that is not yet connected, which are dropped after [`MAX_TIMER_TICKS`]
 186         /// and tracked here.
 187         PendingConnection(VecDeque<OnionMessage>, Option<Vec<SocketAddress>>, usize),
 188 }
 189
 190 impl OnionMessageRecipient {
 191         fn pending_connection(addresses: Vec<SocketAddress>) -> Self {
 192                 Self::PendingConnection(VecDeque::new(), Some(addresses), 0)
 193         }
 194
 195         fn pending_messages(&self) -> &VecDeque<OnionMessage> {
 196                 match self {
 197                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 198                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 199                 }
 200         }
 201
 202         fn enqueue_message(&mut self, message: OnionMessage) {
 203                 let pending_messages = match self {
 204                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 205                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 206                 };
 207
 208                 pending_messages.push_back(message);
 209         }
 210
 211         fn dequeue_message(&mut self) -> Option<OnionMessage> {
 212                 let pending_messages = match self {
 213                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 214                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => {
 215                                 debug_assert!(false);
 216                                 pending_messages
 217                         },
 218                 };
 219
 220                 pending_messages.pop_front()
 221         }
 222
 223         #[cfg(test)]
 224         fn release_pending_messages(&mut self) -> VecDeque<OnionMessage> {
 225                 let pending_messages = match self {
 226                         OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
 227                         OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
 228                 };
 229
 230                 core::mem::take(pending_messages)
 231         }
 232
 233         fn mark_connected(&mut self) {
 234                 if let OnionMessageRecipient::PendingConnection(pending_messages, _, _) = self {
 235                         let mut new_pending_messages = VecDeque::new();
 236                         core::mem::swap(pending_messages, &mut new_pending_messages);
 237                         *self = OnionMessageRecipient::ConnectedPeer(new_pending_messages);
 238                 }
 239         }
 240
 241         fn is_connected(&self) -> bool {
 242                 match self {
 243                         OnionMessageRecipient::ConnectedPeer(..) => true,
 244                         OnionMessageRecipient::PendingConnection(..) => false,
 245                 }
 246         }
 247 }
 248
 249 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 250 ///
 251 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 252 /// enqueued for sending.
 253 #[cfg(not(c_bindings))]
 254 pub struct PendingOnionMessage<T: OnionMessageContents> {
 255         /// The message contents to send in an [`OnionMessage`].
 256         pub contents: T,
 257
 258         /// The destination of the message.
 259         pub destination: Destination,
 260
 261         /// A reply path to include in the [`OnionMessage`] for a response.
 262         pub reply_path: Option<BlindedPath>,
 263 }
 264
 265 #[cfg(c_bindings)]
 266 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 267 ///
 268 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 269 /// enqueued for sending.
 270 pub type PendingOnionMessage<T> = (T, Destination, Option<BlindedPath>);
 271
 272 pub(crate) fn new_pending_onion_message<T: OnionMessageContents>(
 273         contents: T, destination: Destination, reply_path: Option<BlindedPath>
 274 ) -> PendingOnionMessage<T> {
 275         #[cfg(not(c_bindings))]
 276         return PendingOnionMessage { contents, destination, reply_path };
 277         #[cfg(c_bindings)]
 278         return (contents, destination, reply_path);
 279 }
 280
 281 /// A trait defining behavior for routing an [`OnionMessage`].
 282 pub trait MessageRouter {
 283         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 284         fn find_path(
 285                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 286         ) -> Result<OnionMessagePath, ()>;
 287
 288         /// Creates [`BlindedPath`]s to the `recipient` node. The nodes in `peers` are assumed to be
 289         /// direct peers with the `recipient`.
 290         fn create_blinded_paths<
 291                 T: secp256k1::Signing + secp256k1::Verification
 292         >(
 293                 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 294         ) -> Result<Vec<BlindedPath>, ()>;
 295 }
 296
 297 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
 298 pub struct DefaultMessageRouter<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref>
 299 where
 300         L::Target: Logger,
 301         ES::Target: EntropySource,
 302 {
 303         network_graph: G,
 304         entropy_source: ES,
 305 }
 306
 307 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> DefaultMessageRouter<G, L, ES>
 308 where
 309         L::Target: Logger,
 310         ES::Target: EntropySource,
 311 {
 312         /// Creates a [`DefaultMessageRouter`] using the given [`NetworkGraph`].
 313         pub fn new(network_graph: G, entropy_source: ES) -> Self {
 314                 Self { network_graph, entropy_source }
 315         }
 316 }
 317
 318 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> MessageRouter for DefaultMessageRouter<G, L, ES>
 319 where
 320         L::Target: Logger,
 321         ES::Target: EntropySource,
 322 {
 323         fn find_path(
 324                 &self, sender: PublicKey, peers: Vec<PublicKey>, mut destination: Destination
 325         ) -> Result<OnionMessagePath, ()> {
 326                 let network_graph = self.network_graph.deref().read_only();
 327                 destination.resolve(&network_graph);
 328
 329                 let first_node = match destination.first_node() {
 330                         Some(first_node) => first_node,
 331                         None => return Err(()),
 332                 };
 333
 334                 if peers.contains(&first_node) || sender == first_node {
 335                         Ok(OnionMessagePath {
 336                                 intermediate_nodes: vec![], destination, first_node_addresses: None
 337                         })
 338                 } else {
 339                         let node_announcement = network_graph
 340                                 .node(&NodeId::from_pubkey(&first_node))
 341                                 .and_then(|node_info| node_info.announcement_info.as_ref())
 342                                 .and_then(|announcement_info| announcement_info.announcement_message.as_ref())
 343                                 .map(|node_announcement| &node_announcement.contents);
 344
 345                         match node_announcement {
 346                                 Some(node_announcement) if node_announcement.features.supports_onion_messages() => {
 347                                         let first_node_addresses = Some(node_announcement.addresses.clone());
 348                                         Ok(OnionMessagePath {
 349                                                 intermediate_nodes: vec![], destination, first_node_addresses
 350                                         })
 351                                 },
 352                                 _ => Err(()),
 353                         }
 354                 }
 355         }
 356
 357         fn create_blinded_paths<
 358                 T: secp256k1::Signing + secp256k1::Verification
 359         >(
 360                 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 361         ) -> Result<Vec<BlindedPath>, ()> {
 362                 // Limit the number of blinded paths that are computed.
 363                 const MAX_PATHS: usize = 3;
 364
 365                 // Ensure peers have at least three channels so that it is more difficult to infer the
 366                 // recipient's node_id.
 367                 const MIN_PEER_CHANNELS: usize = 3;
 368
 369                 let network_graph = self.network_graph.deref().read_only();
 370                 let is_recipient_announced =
 371                         network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient));
 372
 373                 let mut peer_info = peers.iter()
 374                         // Limit to peers with announced channels
 375                         .filter_map(|pubkey|
 376                                 network_graph
 377                                         .node(&NodeId::from_pubkey(pubkey))
 378                                         .filter(|info| info.channels.len() >= MIN_PEER_CHANNELS)
 379                                         .map(|info| (*pubkey, info.is_tor_only(), info.channels.len()))
 380                         )
 381                         // Exclude Tor-only nodes when the recipient is announced.
 382                         .filter(|(_, is_tor_only, _)| !(*is_tor_only && is_recipient_announced))
 383                         .collect::<Vec<_>>();
 384
 385                 // Prefer using non-Tor nodes with the most channels as the introduction node.
 386                 peer_info.sort_unstable_by(|(_, a_tor_only, a_channels), (_, b_tor_only, b_channels)| {
 387                         a_tor_only.cmp(b_tor_only).then(a_channels.cmp(b_channels).reverse())
 388                 });
 389
 390                 let paths = peer_info.into_iter()
 391                         .map(|(pubkey, _, _)| vec![pubkey, recipient])
 392                         .map(|node_pks| BlindedPath::new_for_message(&node_pks, &*self.entropy_source, secp_ctx))
 393                         .take(MAX_PATHS)
 394                         .collect::<Result<Vec<_>, _>>();
 395
 396                 match paths {
 397                         Ok(paths) if !paths.is_empty() => Ok(paths),
 398                         _ => {
 399                                 if is_recipient_announced {
 400                                         BlindedPath::one_hop_for_message(recipient, &*self.entropy_source, secp_ctx)
 401                                                 .map(|path| vec![path])
 402                                 } else {
 403                                         Err(())
 404                                 }
 405                         },
 406                 }
 407         }
 408 }
 409
 410 /// A path for sending an [`OnionMessage`].
 411 #[derive(Clone)]
 412 pub struct OnionMessagePath {
 413         /// Nodes on the path between the sender and the destination.
 414         pub intermediate_nodes: Vec<PublicKey>,
 415
 416         /// The recipient of the message.
 417         pub destination: Destination,
 418
 419         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 420         ///
 421         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 422         /// this to initiate such a connection.
 423         pub first_node_addresses: Option<Vec<SocketAddress>>,
 424 }
 425
 426 impl OnionMessagePath {
 427         /// Returns the first node in the path.
 428         pub fn first_node(&self) -> Option<PublicKey> {
 429                 self.intermediate_nodes
 430                         .first()
 431                         .copied()
 432                         .or_else(|| self.destination.first_node())
 433         }
 434 }
 435
 436 /// The destination of an onion message.
 437 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 438 pub enum Destination {
 439         /// We're sending this onion message to a node.
 440         Node(PublicKey),
 441         /// We're sending this onion message to a blinded path.
 442         BlindedPath(BlindedPath),
 443 }
 444
 445 impl Destination {
 446         /// Attempts to resolve the [`IntroductionNode::DirectedShortChannelId`] of a
 447         /// [`Destination::BlindedPath`] to a [`IntroductionNode::NodeId`], if applicable, using the
 448         /// provided [`ReadOnlyNetworkGraph`].
 449         pub fn resolve(&mut self, network_graph: &ReadOnlyNetworkGraph) {
 450                 if let Destination::BlindedPath(path) = self {
 451                         if let IntroductionNode::DirectedShortChannelId(..) = path.introduction_node {
 452                                 if let Some(pubkey) = path
 453                                         .public_introduction_node_id(network_graph)
 454                                         .and_then(|node_id| node_id.as_pubkey().ok())
 455                                 {
 456                                         path.introduction_node = IntroductionNode::NodeId(pubkey);
 457                                 }
 458                         }
 459                 }
 460         }
 461
 462         pub(super) fn num_hops(&self) -> usize {
 463                 match self {
 464                         Destination::Node(_) => 1,
 465                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 466                 }
 467         }
 468
 469         fn first_node(&self) -> Option<PublicKey> {
 470                 match self {
 471                         Destination::Node(node_id) => Some(*node_id),
 472                         Destination::BlindedPath(BlindedPath { introduction_node, .. }) => {
 473                                 match introduction_node {
 474                                         IntroductionNode::NodeId(pubkey) => Some(*pubkey),
 475                                         IntroductionNode::DirectedShortChannelId(..) => None,
 476                                 }
 477                         },
 478                 }
 479         }
 480 }
 481
 482 /// Result of successfully [sending an onion message].
 483 ///
 484 /// [sending an onion message]: OnionMessenger::send_onion_message
 485 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 486 pub enum SendSuccess {
 487         /// The message was buffered and will be sent once it is processed by
 488         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 489         Buffered,
 490         /// The message was buffered and will be sent once the node is connected as a peer and it is
 491         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 492         BufferedAwaitingConnection(PublicKey),
 493 }
 494
 495 /// Errors that may occur when [sending an onion message].
 496 ///
 497 /// [sending an onion message]: OnionMessenger::send_onion_message
 498 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
 499 pub enum SendError {
 500         /// Errored computing onion message packet keys.
 501         Secp256k1(secp256k1::Error),
 502         /// Because implementations such as Eclair will drop onion messages where the message packet
 503         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 504         TooBigPacket,
 505         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 506         /// hops.
 507         TooFewBlindedHops,
 508         /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
 509         InvalidFirstHop(PublicKey),
 510         /// A path from the sender to the destination could not be found by the [`MessageRouter`].
 511         PathNotFound,
 512         /// Onion message contents must have a TLV type >= 64.
 513         InvalidMessage,
 514         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 515         BufferFull,
 516         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 517         ///
 518         /// [`NodeSigner`]: crate::sign::NodeSigner
 519         GetNodeIdFailed,
 520         /// The provided [`Destination`] has a blinded path with an unresolved introduction node. An
 521         /// attempt to resolve it in the [`MessageRouter`] when finding an [`OnionMessagePath`] likely
 522         /// failed.
 523         UnresolvedIntroductionNode,
 524         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 525         /// advance the blinded path to make the second hop the new introduction node. Either
 526         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 527         /// new blinding point, or we were attempting to send to ourselves.
 528         BlindedPathAdvanceFailed,
 529 }
 530
 531 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 532 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 533 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 534 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 535 /// message types.
 536 ///
 537 /// See [`OnionMessenger`] for example usage.
 538 ///
 539 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 540 /// [`CustomMessage`]: Self::CustomMessage
 541 pub trait CustomOnionMessageHandler {
 542         /// The message known to the handler. To support multiple message types, you may want to make this
 543         /// an enum with a variant for each supported message.
 544         type CustomMessage: OnionMessageContents;
 545
 546         /// Called with the custom message that was received, returning a response to send, if any.
 547         ///
 548         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 549         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 550
 551         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 552         /// message type is unknown.
 553         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 554
 555         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 556         ///
 557         /// Typically, this is used for messages initiating a message flow rather than in response to
 558         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 559         #[cfg(not(c_bindings))]
 560         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 561
 562         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 563         ///
 564         /// Typically, this is used for messages initiating a message flow rather than in response to
 565         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 566         #[cfg(c_bindings)]
 567         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 568 }
 569
 570 /// A processed incoming onion message, containing either a Forward (another onion message)
 571 /// or a Receive payload with decrypted contents.
 572 #[derive(Debug)]
 573 pub enum PeeledOnion<T: OnionMessageContents> {
 574         /// Forwarded onion, with the next node id and a new onion
 575         Forward(NextHop, OnionMessage),
 576         /// Received onion message, with decrypted contents, path_id, and reply path
 577         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 578 }
 579
 580
 581 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 582 /// `path`, first calling [`Destination::resolve`] on `path.destination` with the given
 583 /// [`ReadOnlyNetworkGraph`].
 584 ///
 585 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 586 /// needed to connect to the first node.
 587 pub fn create_onion_message_resolving_destination<
 588         ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents
 589 >(
 590         entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
 591         network_graph: &ReadOnlyNetworkGraph, secp_ctx: &Secp256k1<secp256k1::All>,
 592         mut path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 593 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 594 where
 595         ES::Target: EntropySource,
 596         NS::Target: NodeSigner,
 597         NL::Target: NodeIdLookUp,
 598 {
 599         path.destination.resolve(network_graph);
 600         create_onion_message(
 601                 entropy_source, node_signer, node_id_lookup, secp_ctx, path, contents, reply_path,
 602         )
 603 }
 604
 605 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 606 /// `path`.
 607 ///
 608 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
 609 /// needed to connect to the first node.
 610 ///
 611 /// Returns [`SendError::UnresolvedIntroductionNode`] if:
 612 /// - `destination` contains a blinded path with an [`IntroductionNode::DirectedShortChannelId`],
 613 /// - unless it can be resolved by [`NodeIdLookUp::next_node_id`].
 614 /// Use [`create_onion_message_resolving_destination`] instead to resolve the introduction node
 615 /// first with a [`ReadOnlyNetworkGraph`].
 616 pub fn create_onion_message<ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents>(
 617         entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
 618         secp_ctx: &Secp256k1<secp256k1::All>, path: OnionMessagePath, contents: T,
 619         reply_path: Option<BlindedPath>,
 620 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 621 where
 622         ES::Target: EntropySource,
 623         NS::Target: NodeSigner,
 624         NL::Target: NodeIdLookUp,
 625 {
 626         let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
 627         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 628                 if blinded_hops.is_empty() {
 629                         return Err(SendError::TooFewBlindedHops);
 630                 }
 631         }
 632
 633         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 634
 635         // If we are sending straight to a blinded path and we are the introduction node, we need to
 636         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 637         if intermediate_nodes.len() == 0 {
 638                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 639                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 640                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 641                         let introduction_node_id = match blinded_path.introduction_node {
 642                                 IntroductionNode::NodeId(pubkey) => pubkey,
 643                                 IntroductionNode::DirectedShortChannelId(direction, scid) => {
 644                                         match node_id_lookup.next_node_id(scid) {
 645                                                 Some(next_node_id) => *direction.select_pubkey(&our_node_id, &next_node_id),
 646                                                 None => return Err(SendError::UnresolvedIntroductionNode),
 647                                         }
 648                                 },
 649                         };
 650                         if introduction_node_id == our_node_id {
 651                                 advance_path_by_one(blinded_path, node_signer, node_id_lookup, &secp_ctx)
 652                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 653                         }
 654                 }
 655         }
 656
 657         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 658         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 659         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 660                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 661         } else {
 662                 match &destination {
 663                         Destination::Node(pk) => (*pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 664                         Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, .. }) => {
 665                                 match introduction_node {
 666                                         IntroductionNode::NodeId(pubkey) => (*pubkey, *blinding_point),
 667                                         IntroductionNode::DirectedShortChannelId(..) => {
 668                                                 return Err(SendError::UnresolvedIntroductionNode);
 669                                         },
 670                                 }
 671                         }
 672                 }
 673         };
 674         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 675                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret
 676         )?;
 677
 678         let prng_seed = entropy_source.get_secure_random_bytes();
 679         let onion_routing_packet = construct_onion_message_packet(
 680                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 681
 682         let message = OnionMessage { blinding_point, onion_routing_packet };
 683         Ok((first_node_id, message, first_node_addresses))
 684 }
 685
 686 /// Decode one layer of an incoming [`OnionMessage`].
 687 ///
 688 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 689 /// receiver.
 690 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 691         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 692         custom_handler: CMH,
 693 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 694 where
 695         NS::Target: NodeSigner,
 696         L::Target: Logger,
 697         CMH::Target: CustomOnionMessageHandler,
 698 {
 699         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 700                 Ok(ss) => ss,
 701                 Err(e) =>  {
 702                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 703                         return Err(());
 704                 }
 705         };
 706         let onion_decode_ss = {
 707                 let blinding_factor = {
 708                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 709                         hmac.input(control_tlvs_ss.as_ref());
 710                         Hmac::from_engine(hmac).to_byte_array()
 711                 };
 712                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 713                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 714                 {
 715                         Ok(ss) => ss.secret_bytes(),
 716                         Err(()) => {
 717                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 718                                 return Err(());
 719                         }
 720                 }
 721         };
 722         match onion_utils::decode_next_untagged_hop(
 723                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 724                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 725         ) {
 726                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 727                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 728                 }, None)) => {
 729                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 730                 },
 731                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 732                         next_hop, next_blinding_override
 733                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 734                         // TODO: we need to check whether `next_hop` is our node, in which case this is a dummy
 735                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 736                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 737                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 738                         // for now.
 739                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 740                                 Ok(pk) => pk,
 741                                 Err(e) => {
 742                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 743                                         return Err(())
 744                                 }
 745                         };
 746                         let outgoing_packet = Packet {
 747                                 version: 0,
 748                                 public_key: new_pubkey,
 749                                 hop_data: new_packet_bytes,
 750                                 hmac: next_hop_hmac,
 751                         };
 752                         let onion_message = OnionMessage {
 753                                 blinding_point: match next_blinding_override {
 754                                         Some(blinding_point) => blinding_point,
 755                                         None => {
 756                                                 match onion_utils::next_hop_pubkey(
 757                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 758                                                 ) {
 759                                                         Ok(bp) => bp,
 760                                                         Err(e) => {
 761                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 762                                                                 return Err(())
 763                                                         }
 764                                                 }
 765                                         }
 766                                 },
 767                                 onion_routing_packet: outgoing_packet,
 768                         };
 769
 770                         Ok(PeeledOnion::Forward(next_hop, onion_message))
 771                 },
 772                 Err(e) => {
 773                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 774                         Err(())
 775                 },
 776                 _ => {
 777                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 778                         Err(())
 779                 },
 780         }
 781 }
 782
 783 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 784 OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
 785 where
 786         ES::Target: EntropySource,
 787         NS::Target: NodeSigner,
 788         L::Target: Logger,
 789         NL::Target: NodeIdLookUp,
 790         MR::Target: MessageRouter,
 791         OMH::Target: OffersMessageHandler,
 792         CMH::Target: CustomOnionMessageHandler,
 793 {
 794         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 795         /// their respective handlers.
 796         pub fn new(
 797                 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL, message_router: MR,
 798                 offers_handler: OMH, custom_handler: CMH
 799         ) -> Self {
 800                 let mut secp_ctx = Secp256k1::new();
 801                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 802                 OnionMessenger {
 803                         entropy_source,
 804                         node_signer,
 805                         message_recipients: Mutex::new(new_hash_map()),
 806                         secp_ctx,
 807                         logger,
 808                         node_id_lookup,
 809                         message_router,
 810                         offers_handler,
 811                         custom_handler,
 812                 }
 813         }
 814
 815         #[cfg(test)]
 816         pub(crate) fn set_offers_handler(&mut self, offers_handler: OMH) {
 817                 self.offers_handler = offers_handler;
 818         }
 819
 820         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
 821         ///
 822         /// See [`OnionMessenger`] for example usage.
 823         pub fn send_onion_message<T: OnionMessageContents>(
 824                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
 825         ) -> Result<SendSuccess, SendError> {
 826                 self.find_path_and_enqueue_onion_message(
 827                         contents, destination, reply_path, format_args!("")
 828                 )
 829         }
 830
 831         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 832                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 833                 log_suffix: fmt::Arguments
 834         ) -> Result<SendSuccess, SendError> {
 835                 let mut logger = WithContext::from(&self.logger, None, None);
 836                 let result = self.find_path(destination)
 837                         .and_then(|path| {
 838                                 let first_hop = path.intermediate_nodes.get(0).map(|p| *p);
 839                                 logger = WithContext::from(&self.logger, first_hop, None);
 840                                 self.enqueue_onion_message(path, contents, reply_path, log_suffix)
 841                         });
 842
 843                 match result.as_ref() {
 844                         Err(SendError::GetNodeIdFailed) => {
 845                                 log_warn!(logger, "Unable to retrieve node id {}", log_suffix);
 846                         },
 847                         Err(SendError::PathNotFound) => {
 848                                 log_trace!(logger, "Failed to find path {}", log_suffix);
 849                         },
 850                         Err(e) => {
 851                                 log_trace!(logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 852                         },
 853                         Ok(SendSuccess::Buffered) => {
 854                                 log_trace!(logger, "Buffered onion message {}", log_suffix);
 855                         },
 856                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
 857                                 log_trace!(
 858                                         logger,
 859                                         "Buffered onion message waiting on peer connection {}: {}",
 860                                         log_suffix, node_id
 861                                 );
 862                         },
 863                 }
 864
 865                 result
 866         }
 867
 868         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
 869                 let sender = self.node_signer
 870                         .get_node_id(Recipient::Node)
 871                         .map_err(|_| SendError::GetNodeIdFailed)?;
 872
 873                 let peers = self.message_recipients.lock().unwrap()
 874                         .iter()
 875                         .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
 876                         .map(|(node_id, _)| *node_id)
 877                         .collect();
 878
 879                 self.message_router
 880                         .find_path(sender, peers, destination)
 881                         .map_err(|_| SendError::PathNotFound)
 882         }
 883
 884         fn enqueue_onion_message<T: OnionMessageContents>(
 885                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 886                 log_suffix: fmt::Arguments
 887         ) -> Result<SendSuccess, SendError> {
 888                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 889
 890                 let (first_node_id, onion_message, addresses) = create_onion_message(
 891                         &self.entropy_source, &self.node_signer, &self.node_id_lookup, &self.secp_ctx, path,
 892                         contents, reply_path,
 893                 )?;
 894
 895                 let mut message_recipients = self.message_recipients.lock().unwrap();
 896                 if outbound_buffer_full(&first_node_id, &message_recipients) {
 897                         return Err(SendError::BufferFull);
 898                 }
 899
 900                 match message_recipients.entry(first_node_id) {
 901                         hash_map::Entry::Vacant(e) => match addresses {
 902                                 None => Err(SendError::InvalidFirstHop(first_node_id)),
 903                                 Some(addresses) => {
 904                                         e.insert(OnionMessageRecipient::pending_connection(addresses))
 905                                                 .enqueue_message(onion_message);
 906                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 907                                 },
 908                         },
 909                         hash_map::Entry::Occupied(mut e) => {
 910                                 e.get_mut().enqueue_message(onion_message);
 911                                 if e.get().is_connected() {
 912                                         Ok(SendSuccess::Buffered)
 913                                 } else {
 914                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 915                                 }
 916                         },
 917                 }
 918         }
 919
 920         #[cfg(any(test, feature = "_test_utils"))]
 921         pub fn send_onion_message_using_path<T: OnionMessageContents>(
 922                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
 923         ) -> Result<SendSuccess, SendError> {
 924                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
 925         }
 926
 927         pub(crate) fn peel_onion_message(
 928                 &self, msg: &OnionMessage
 929         ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()> {
 930                 peel_onion_message(
 931                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
 932                 )
 933         }
 934
 935         fn handle_onion_message_response<T: OnionMessageContents>(
 936                 &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
 937         ) {
 938                 if let Some(response) = response {
 939                         match reply_path {
 940                                 Some(reply_path) => {
 941                                         let _ = self.find_path_and_enqueue_onion_message(
 942                                                 response, Destination::BlindedPath(reply_path), None, log_suffix
 943                                         );
 944                                 },
 945                                 None => {
 946                                         log_trace!(self.logger, "Missing reply path {}", log_suffix);
 947                                 },
 948                         }
 949                 }
 950         }
 951
 952         #[cfg(test)]
 953         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 954                 let mut message_recipients = self.message_recipients.lock().unwrap();
 955                 let mut msgs = new_hash_map();
 956                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 957                 // release the pending message buffers individually.
 958                 for (node_id, recipient) in &mut *message_recipients {
 959                         msgs.insert(*node_id, recipient.release_pending_messages());
 960                 }
 961                 msgs
 962         }
 963 }
 964
 965 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
 966         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 967         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 968         let mut total_buffered_bytes = 0;
 969         let mut peer_buffered_bytes = 0;
 970         for (pk, peer_buf) in buffer {
 971                 for om in peer_buf.pending_messages() {
 972                         let om_len = om.serialized_length();
 973                         if pk == peer_node_id {
 974                                 peer_buffered_bytes += om_len;
 975                         }
 976                         total_buffered_bytes += om_len;
 977
 978                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 979                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 980                         {
 981                                 return true
 982                         }
 983                 }
 984         }
 985         false
 986 }
 987
 988 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
 989 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
 990 where
 991         ES::Target: EntropySource,
 992         NS::Target: NodeSigner,
 993         L::Target: Logger,
 994         NL::Target: NodeIdLookUp,
 995         MR::Target: MessageRouter,
 996         OMH::Target: OffersMessageHandler,
 997         CMH::Target: CustomOnionMessageHandler,
 998 {
 999         fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
1000                 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
1001                         if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
1002                                 if let Some(addresses) = addresses.take() {
1003                                         handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
1004                                 }
1005                         }
1006                 }
1007         }
1008 }
1009
1010 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
1011 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
1012 where
1013         ES::Target: EntropySource,
1014         NS::Target: NodeSigner,
1015         L::Target: Logger,
1016         NL::Target: NodeIdLookUp,
1017         MR::Target: MessageRouter,
1018         OMH::Target: OffersMessageHandler,
1019         CMH::Target: CustomOnionMessageHandler,
1020 {
1021         fn handle_onion_message(&self, peer_node_id: &PublicKey, msg: &OnionMessage) {
1022                 let logger = WithContext::from(&self.logger, Some(*peer_node_id), None);
1023                 match self.peel_onion_message(msg) {
1024                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
1025                                 log_trace!(
1026                                         logger,
1027                                         "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
1028                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
1029
1030                                 match message {
1031                                         ParsedOnionMessageContents::Offers(msg) => {
1032                                                 let response = self.offers_handler.handle_message(msg);
1033                                                 self.handle_onion_message_response(
1034                                                         response, reply_path, format_args!(
1035                                                                 "when responding to Offers onion message with path_id {:02x?}",
1036                                                                 path_id
1037                                                         )
1038                                                 );
1039                                         },
1040                                         ParsedOnionMessageContents::Custom(msg) => {
1041                                                 let response = self.custom_handler.handle_custom_message(msg);
1042                                                 self.handle_onion_message_response(
1043                                                         response, reply_path, format_args!(
1044                                                                 "when responding to Custom onion message with path_id {:02x?}",
1045                                                                 path_id
1046                                                         )
1047                                                 );
1048                                         },
1049                                 }
1050                         },
1051                         Ok(PeeledOnion::Forward(next_hop, onion_message)) => {
1052                                 let next_node_id = match next_hop {
1053                                         NextHop::NodeId(pubkey) => pubkey,
1054                                         NextHop::ShortChannelId(scid) => match self.node_id_lookup.next_node_id(scid) {
1055                                                 Some(pubkey) => pubkey,
1056                                                 None => {
1057                                                         log_trace!(self.logger, "Dropping forwarded onion messager: unable to resolve next hop using SCID {}", scid);
1058                                                         return
1059                                                 },
1060                                         },
1061                                 };
1062
1063                                 let mut message_recipients = self.message_recipients.lock().unwrap();
1064                                 if outbound_buffer_full(&next_node_id, &message_recipients) {
1065                                         log_trace!(
1066                                                 logger,
1067                                                 "Dropping forwarded onion message to peer {}: outbound buffer full",
1068                                                 next_node_id);
1069                                         return
1070                                 }
1071
1072                                 #[cfg(fuzzing)]
1073                                 message_recipients
1074                                         .entry(next_node_id)
1075                                         .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
1076
1077                                 match message_recipients.entry(next_node_id) {
1078                                         hash_map::Entry::Occupied(mut e) if matches!(
1079                                                 e.get(), OnionMessageRecipient::ConnectedPeer(..)
1080                                         ) => {
1081                                                 e.get_mut().enqueue_message(onion_message);
1082                                                 log_trace!(logger, "Forwarding an onion message to peer {}", next_node_id);
1083                                         },
1084                                         _ => {
1085                                                 log_trace!(
1086                                                         logger,
1087                                                         "Dropping forwarded onion message to disconnected peer {}",
1088                                                         next_node_id);
1089                                                 return
1090                                         },
1091                                 }
1092                         },
1093                         Err(e) => {
1094                                 log_error!(logger, "Failed to process onion message {:?}", e);
1095                         }
1096                 }
1097         }
1098
1099         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
1100                 if init.features.supports_onion_messages() {
1101                         self.message_recipients.lock().unwrap()
1102                                 .entry(*their_node_id)
1103                                 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
1104                                 .mark_connected();
1105                 } else {
1106                         self.message_recipients.lock().unwrap().remove(their_node_id);
1107                 }
1108
1109                 Ok(())
1110         }
1111
1112         fn peer_disconnected(&self, their_node_id: &PublicKey) {
1113                 match self.message_recipients.lock().unwrap().remove(their_node_id) {
1114                         Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
1115                         Some(_) => debug_assert!(false),
1116                         None => {},
1117                 }
1118         }
1119
1120         fn timer_tick_occurred(&self) {
1121                 let mut message_recipients = self.message_recipients.lock().unwrap();
1122
1123                 // Drop any pending recipients since the last call to avoid retaining buffered messages for
1124                 // too long.
1125                 message_recipients.retain(|_, recipient| match recipient {
1126                         OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
1127                         OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
1128                         _ => true,
1129                 });
1130
1131                 // Increment a timer tick for pending recipients so that their buffered messages are dropped
1132                 // at MAX_TIMER_TICKS.
1133                 for recipient in message_recipients.values_mut() {
1134                         if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
1135                                 *ticks += 1;
1136                         }
1137                 }
1138         }
1139
1140         fn provided_node_features(&self) -> NodeFeatures {
1141                 let mut features = NodeFeatures::empty();
1142                 features.set_onion_messages_optional();
1143                 features
1144         }
1145
1146         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1147                 let mut features = InitFeatures::empty();
1148                 features.set_onion_messages_optional();
1149                 features
1150         }
1151
1152         // Before returning any messages to send for the peer, this method will see if any messages were
1153         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1154         // node, and then enqueue the message for sending to the first peer in the full path.
1155         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1156                 // Enqueue any initiating `OffersMessage`s to send.
1157                 for message in self.offers_handler.release_pending_messages() {
1158                         #[cfg(not(c_bindings))]
1159                         let PendingOnionMessage { contents, destination, reply_path } = message;
1160                         #[cfg(c_bindings)]
1161                         let (contents, destination, reply_path) = message;
1162                         let _ = self.find_path_and_enqueue_onion_message(
1163                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
1164                         );
1165                 }
1166
1167                 // Enqueue any initiating `CustomMessage`s to send.
1168                 for message in self.custom_handler.release_pending_custom_messages() {
1169                         #[cfg(not(c_bindings))]
1170                         let PendingOnionMessage { contents, destination, reply_path } = message;
1171                         #[cfg(c_bindings)]
1172                         let (contents, destination, reply_path) = message;
1173                         let _ = self.find_path_and_enqueue_onion_message(
1174                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
1175                         );
1176                 }
1177
1178                 self.message_recipients.lock().unwrap()
1179                         .get_mut(&peer_node_id)
1180                         .and_then(|buffer| buffer.dequeue_message())
1181         }
1182 }
1183
1184 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1185 // produces
1186 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1187 /// [`SimpleArcPeerManager`]. See their docs for more details.
1188 ///
1189 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1190 ///
1191 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1192 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1193 #[cfg(not(c_bindings))]
1194 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1195         Arc<KeysManager>,
1196         Arc<KeysManager>,
1197         Arc<L>,
1198         Arc<SimpleArcChannelManager<M, T, F, L>>,
1199         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>, Arc<KeysManager>>>,
1200         Arc<SimpleArcChannelManager<M, T, F, L>>,
1201         IgnoringMessageHandler
1202 >;
1203
1204 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1205 /// [`SimpleRefPeerManager`]. See their docs for more details.
1206 ///
1207 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1208 ///
1209 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1210 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1211 #[cfg(not(c_bindings))]
1212 pub type SimpleRefOnionMessenger<
1213         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1214 > = OnionMessenger<
1215         &'a KeysManager,
1216         &'a KeysManager,
1217         &'b L,
1218         &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1219         &'j DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L, &'a KeysManager>,
1220         &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1221         IgnoringMessageHandler
1222 >;
1223
1224 /// Construct onion packet payloads and keys for sending an onion message along the given
1225 /// `unblinded_path` to the given `destination`.
1226 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1227         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1228         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1229 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), SendError> {
1230         let num_hops = unblinded_path.len() + destination.num_hops();
1231         let mut payloads = Vec::with_capacity(num_hops);
1232         let mut onion_packet_keys = Vec::with_capacity(num_hops);
1233
1234         let (mut intro_node_id_blinding_pt, num_blinded_hops) = match &destination {
1235                 Destination::Node(_) => (None, 0),
1236                 Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, blinded_hops }) => {
1237                         let introduction_node_id = match introduction_node {
1238                                 IntroductionNode::NodeId(pubkey) => pubkey,
1239                                 IntroductionNode::DirectedShortChannelId(..) => {
1240                                         return Err(SendError::UnresolvedIntroductionNode);
1241                                 },
1242                         };
1243                         (Some((*introduction_node_id, *blinding_point)), blinded_hops.len())
1244                 },
1245         };
1246         let num_unblinded_hops = num_hops - num_blinded_hops;
1247
1248         let mut unblinded_path_idx = 0;
1249         let mut blinded_path_idx = 0;
1250         let mut prev_control_tlvs_ss = None;
1251         let mut final_control_tlvs = None;
1252         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1253                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1254                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1255                                 if let Some(ss) = prev_control_tlvs_ss.take() {
1256                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1257                                                 ForwardTlvs {
1258                                                         next_hop: NextHop::NodeId(unblinded_pk_opt.unwrap()),
1259                                                         next_blinding_override: None,
1260                                                 }
1261                                         )), ss));
1262                                 }
1263                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1264                                 unblinded_path_idx += 1;
1265                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1266                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1267                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1268                                                 next_hop: NextHop::NodeId(intro_node_id),
1269                                                 next_blinding_override: Some(blinding_pt),
1270                                         })), control_tlvs_ss));
1271                                 }
1272                         }
1273                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1274                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1275                                         control_tlvs_ss));
1276                                 blinded_path_idx += 1;
1277                         } else if let Some(encrypted_payload) = enc_payload_opt {
1278                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1279                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1280                         }
1281
1282                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1283                         onion_packet_keys.push(onion_utils::OnionKeys {
1284                                 #[cfg(test)]
1285                                 shared_secret: onion_packet_ss,
1286                                 #[cfg(test)]
1287                                 blinding_factor: [0; 32],
1288                                 ephemeral_pubkey,
1289                                 rho,
1290                                 mu,
1291                         });
1292                 }
1293         ).map_err(|e| SendError::Secp256k1(e))?;
1294
1295         if let Some(control_tlvs) = final_control_tlvs {
1296                 payloads.push((Payload::Receive {
1297                         control_tlvs,
1298                         reply_path: reply_path.take(),
1299                         message,
1300                 }, prev_control_tlvs_ss.unwrap()));
1301         } else {
1302                 payloads.push((Payload::Receive {
1303                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1304                         reply_path: reply_path.take(),
1305                         message,
1306                 }, prev_control_tlvs_ss.unwrap()));
1307         }
1308
1309         Ok((payloads, onion_packet_keys))
1310 }
1311
1312 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1313 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, ()> {
1314         // Spec rationale:
1315         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1316         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1317         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1318         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1319         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1320                 SMALL_PACKET_HOP_DATA_LEN
1321         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1322                 BIG_PACKET_HOP_DATA_LEN
1323         } else { return Err(()) };
1324
1325         onion_utils::construct_onion_message_packet::<_, _>(
1326                 payloads, onion_keys, prng_seed, hop_data_len)
1327 }