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

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