_ 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 use crate::events::OnionMessageProvider;
  23 use crate::ln::features::{InitFeatures, NodeFeatures};
  24 use crate::ln::msgs::{self, OnionMessageHandler};
  25 use crate::ln::onion_utils;
  26 use crate::ln::peer_handler::IgnoringMessageHandler;
  27 pub use super::packet::{CustomOnionMessageContents, OnionMessageContents};
  28 use super::offers::OffersMessageHandler;
  29 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  30 use crate::util::logger::Logger;
  31 use crate::util::ser::Writeable;
  32
  33 use core::ops::Deref;
  34 use crate::io;
  35 use crate::sync::{Arc, Mutex};
  36 use crate::prelude::*;
  37
  38 /// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be
  39 /// used to retrieve invoices and fulfill invoice requests from [offers]. Currently, only sending
  40 /// and receiving custom onion messages is supported.
  41 ///
  42 /// # Example
  43 ///
  44 /// ```
  45 /// # extern crate bitcoin;
  46 /// # use bitcoin::hashes::_export::_core::time::Duration;
  47 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
  48 /// # use lightning::blinded_path::BlindedPath;
  49 /// # use lightning::sign::KeysManager;
  50 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  51 /// # use lightning::onion_message::{CustomOnionMessageContents, Destination, MessageRouter, OnionMessageContents, OnionMessagePath, OnionMessenger};
  52 /// # use lightning::util::logger::{Logger, Record};
  53 /// # use lightning::util::ser::{Writeable, Writer};
  54 /// # use lightning::io;
  55 /// # use std::sync::Arc;
  56 /// # struct FakeLogger;
  57 /// # impl Logger for FakeLogger {
  58 /// #     fn log(&self, record: &Record) { unimplemented!() }
  59 /// # }
  60 /// # struct FakeMessageRouter {}
  61 /// # impl MessageRouter for FakeMessageRouter {
  62 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  63 /// #         unimplemented!()
  64 /// #     }
  65 /// # }
  66 /// # let seed = [42u8; 32];
  67 /// # let time = Duration::from_secs(123456);
  68 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
  69 /// # let logger = Arc::new(FakeLogger {});
  70 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  71 /// # let secp_ctx = Secp256k1::new();
  72 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  73 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
  74 /// # let destination_node_id = hop_node_id1;
  75 /// # let message_router = Arc::new(FakeMessageRouter {});
  76 /// # let custom_message_handler = IgnoringMessageHandler {};
  77 /// # let offers_message_handler = IgnoringMessageHandler {};
  78 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
  79 /// // ChannelManager.
  80 /// let onion_messenger = OnionMessenger::new(
  81 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
  82 ///     &custom_message_handler
  83 /// );
  84 ///
  85 /// # struct YourCustomMessage {}
  86 /// impl Writeable for YourCustomMessage {
  87 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  88 ///             # Ok(())
  89 ///             // Write your custom onion message to `w`
  90 ///     }
  91 /// }
  92 /// impl CustomOnionMessageContents for YourCustomMessage {
  93 ///     fn tlv_type(&self) -> u64 {
  94 ///             # let your_custom_message_type = 42;
  95 ///             your_custom_message_type
  96 ///     }
  97 /// }
  98 /// // Send a custom onion message to a node id.
  99 /// let path = OnionMessagePath {
 100 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 101 ///     destination: Destination::Node(destination_node_id),
 102 /// };
 103 /// let reply_path = None;
 104 /// # let your_custom_message = YourCustomMessage {};
 105 /// let message = OnionMessageContents::Custom(your_custom_message);
 106 /// onion_messenger.send_onion_message(path, message, reply_path);
 107 ///
 108 /// // Create a blinded path to yourself, for someone to send an onion message to.
 109 /// # let your_node_id = hop_node_id1;
 110 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 111 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 112 ///
 113 /// // Send a custom onion message to a blinded path.
 114 /// let path = OnionMessagePath {
 115 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
 116 ///     destination: Destination::BlindedPath(blinded_path),
 117 /// };
 118 /// let reply_path = None;
 119 /// # let your_custom_message = YourCustomMessage {};
 120 /// let message = OnionMessageContents::Custom(your_custom_message);
 121 /// onion_messenger.send_onion_message(path, message, reply_path);
 122 /// ```
 123 ///
 124 /// [offers]: <https://github.com/lightning/bolts/pull/798>
 125 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
 126 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 127 where
 128         ES::Target: EntropySource,
 129         NS::Target: NodeSigner,
 130         L::Target: Logger,
 131         MR::Target: MessageRouter,
 132         OMH::Target: OffersMessageHandler,
 133         CMH:: Target: CustomOnionMessageHandler,
 134 {
 135         entropy_source: ES,
 136         node_signer: NS,
 137         logger: L,
 138         pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
 139         secp_ctx: Secp256k1<secp256k1::All>,
 140         message_router: MR,
 141         offers_handler: OMH,
 142         custom_handler: CMH,
 143 }
 144
 145 /// A trait defining behavior for routing an [`OnionMessage`].
 146 ///
 147 /// [`OnionMessage`]: msgs::OnionMessage
 148 pub trait MessageRouter {
 149         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 150         ///
 151         /// [`OnionMessage`]: msgs::OnionMessage
 152         fn find_path(
 153                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 154         ) -> Result<OnionMessagePath, ()>;
 155 }
 156
 157 /// A [`MessageRouter`] that always fails.
 158 pub struct DefaultMessageRouter;
 159
 160 impl MessageRouter for DefaultMessageRouter {
 161         fn find_path(
 162                 &self, _sender: PublicKey, _peers: Vec<PublicKey>, _destination: Destination
 163         ) -> Result<OnionMessagePath, ()> {
 164                 Err(())
 165         }
 166 }
 167
 168 /// A path for sending an [`msgs::OnionMessage`].
 169 #[derive(Clone)]
 170 pub struct OnionMessagePath {
 171         /// Nodes on the path between the sender and the destination.
 172         pub intermediate_nodes: Vec<PublicKey>,
 173
 174         /// The recipient of the message.
 175         pub destination: Destination,
 176 }
 177
 178 /// The destination of an onion message.
 179 #[derive(Clone)]
 180 pub enum Destination {
 181         /// We're sending this onion message to a node.
 182         Node(PublicKey),
 183         /// We're sending this onion message to a blinded path.
 184         BlindedPath(BlindedPath),
 185 }
 186
 187 impl Destination {
 188         pub(super) fn num_hops(&self) -> usize {
 189                 match self {
 190                         Destination::Node(_) => 1,
 191                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 192                 }
 193         }
 194 }
 195
 196 /// Errors that may occur when [sending an onion message].
 197 ///
 198 /// [sending an onion message]: OnionMessenger::send_onion_message
 199 #[derive(Debug, PartialEq, Eq)]
 200 pub enum SendError {
 201         /// Errored computing onion message packet keys.
 202         Secp256k1(secp256k1::Error),
 203         /// Because implementations such as Eclair will drop onion messages where the message packet
 204         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 205         TooBigPacket,
 206         /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two
 207         /// blinded hops.
 208         TooFewBlindedHops,
 209         /// Our next-hop peer was offline or does not support onion message forwarding.
 210         InvalidFirstHop,
 211         /// Onion message contents must have a TLV type >= 64.
 212         InvalidMessage,
 213         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 214         BufferFull,
 215         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 216         ///
 217         /// [`NodeSigner`]: crate::sign::NodeSigner
 218         GetNodeIdFailed,
 219         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 220         /// advance the blinded path to make the second hop the new introduction node. Either
 221         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 222         /// new blinding point, or we were attempting to send to ourselves.
 223         BlindedPathAdvanceFailed,
 224 }
 225
 226 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 227 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 228 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 229 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 230 /// message types.
 231 ///
 232 /// See [`OnionMessenger`] for example usage.
 233 ///
 234 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 235 /// [`CustomMessage`]: Self::CustomMessage
 236 pub trait CustomOnionMessageHandler {
 237         /// The message known to the handler. To support multiple message types, you may want to make this
 238         /// an enum with a variant for each supported message.
 239         type CustomMessage: CustomOnionMessageContents;
 240
 241         /// Called with the custom message that was received, returning a response to send, if any.
 242         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 243
 244         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 245         /// message type is unknown.
 246         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 247 }
 248
 249 /// A processed incoming onion message, containing either a Forward (another onion message)
 250 /// or a Receive payload with decrypted contents.
 251 pub enum PeeledOnion<CM: CustomOnionMessageContents> {
 252         /// Forwarded onion, with the next node id and a new onion
 253         Forward(PublicKey, msgs::OnionMessage),
 254         /// Received onion message, with decrypted contents, path_id, and reply path
 255         Receive(OnionMessageContents<CM>, Option<[u8; 32]>, Option<BlindedPath>)
 256 }
 257
 258 /// Create an onion message with contents `message` to the destination of `path`.
 259 /// Returns (introduction_node_id, onion_msg)
 260 pub fn create_onion_message<ES: Deref, NS: Deref, T: CustomOnionMessageContents>(
 261         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 262         path: OnionMessagePath, message: OnionMessageContents<T>, reply_path: Option<BlindedPath>,
 263 ) -> Result<(PublicKey, msgs::OnionMessage), SendError>
 264 where
 265         ES::Target: EntropySource,
 266         NS::Target: NodeSigner,
 267 {
 268         let OnionMessagePath { intermediate_nodes, mut destination } = path;
 269         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 270                 if blinded_hops.len() < 2 {
 271                         return Err(SendError::TooFewBlindedHops);
 272                 }
 273         }
 274
 275         if message.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 276
 277         // If we are sending straight to a blinded path and we are the introduction node, we need to
 278         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 279         if intermediate_nodes.len() == 0 {
 280                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 281                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 282                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 283                         if blinded_path.introduction_node_id == our_node_id {
 284                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 285                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 286                         }
 287                 }
 288         }
 289
 290         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 291         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 292         let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
 293                 (intermediate_nodes[0], PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 294         } else {
 295                 match destination {
 296                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 297                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 298                                 (introduction_node_id, blinding_point),
 299                 }
 300         };
 301         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 302                 &secp_ctx, &intermediate_nodes, destination, message, reply_path, &blinding_secret)
 303                 .map_err(|e| SendError::Secp256k1(e))?;
 304
 305         let prng_seed = entropy_source.get_secure_random_bytes();
 306         let onion_routing_packet = construct_onion_message_packet(
 307                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 308
 309         Ok((introduction_node_id, msgs::OnionMessage {
 310                 blinding_point,
 311                 onion_routing_packet
 312         }))
 313 }
 314
 315 /// Decode one layer of an incoming onion message
 316 /// Returns either a Forward (another onion message), or Receive (decrypted content)
 317 pub fn peel_onion<NS: Deref, L: Deref, CMH: Deref>(
 318         node_signer: NS, secp_ctx: &Secp256k1<secp256k1::All>, logger: L, custom_handler: CMH,
 319         msg: &msgs::OnionMessage,
 320 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 321 where
 322         NS::Target: NodeSigner,
 323         L::Target: Logger,
 324         CMH::Target: CustomOnionMessageHandler,
 325 {
 326         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 327                 Ok(ss) => ss,
 328                 Err(e) =>  {
 329                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 330                         return Err(());
 331                 }
 332         };
 333         let onion_decode_ss = {
 334                 let blinding_factor = {
 335                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 336                         hmac.input(control_tlvs_ss.as_ref());
 337                         Hmac::from_engine(hmac).into_inner()
 338                 };
 339                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 340                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 341                 {
 342                         Ok(ss) => ss.secret_bytes(),
 343                         Err(()) => {
 344                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 345                                 return Err(());
 346                         }
 347                 }
 348         };
 349         match onion_utils::decode_next_untagged_hop(
 350                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 351                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 352         ) {
 353                 Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
 354                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 355                 }, None)) => {
 356                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 357                 },
 358                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 359                         next_node_id, next_blinding_override
 360                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 361                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 362                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 363                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 364                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 365                         // for now.
 366                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 367                                 Ok(pk) => pk,
 368                                 Err(e) => {
 369                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 370                                         return Err(())
 371                                 }
 372                         };
 373                         let outgoing_packet = Packet {
 374                                 version: 0,
 375                                 public_key: new_pubkey,
 376                                 hop_data: new_packet_bytes,
 377                                 hmac: next_hop_hmac,
 378                         };
 379                         let onion_message = msgs::OnionMessage {
 380                                 blinding_point: match next_blinding_override {
 381                                         Some(blinding_point) => blinding_point,
 382                                         None => {
 383                                                 match onion_utils::next_hop_pubkey(
 384                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 385                                                 ) {
 386                                                         Ok(bp) => bp,
 387                                                         Err(e) => {
 388                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 389                                                                 return Err(())
 390                                                         }
 391                                                 }
 392                                         }
 393                                 },
 394                                 onion_routing_packet: outgoing_packet,
 395                         };
 396
 397                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 398                 },
 399                 Err(e) => {
 400                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 401                         Err(())
 402                 },
 403                 _ => {
 404                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 405                         Err(())
 406                 },
 407         }
 408 }
 409
 410 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 411 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 412 where
 413         ES::Target: EntropySource,
 414         NS::Target: NodeSigner,
 415         L::Target: Logger,
 416         MR::Target: MessageRouter,
 417         OMH::Target: OffersMessageHandler,
 418         CMH::Target: CustomOnionMessageHandler,
 419 {
 420         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 421         /// their respective handlers.
 422         pub fn new(
 423                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 424                 custom_handler: CMH
 425         ) -> Self {
 426                 let mut secp_ctx = Secp256k1::new();
 427                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 428                 OnionMessenger {
 429                         entropy_source,
 430                         node_signer,
 431                         pending_messages: Mutex::new(HashMap::new()),
 432                         secp_ctx,
 433                         logger,
 434                         message_router,
 435                         offers_handler,
 436                         custom_handler,
 437                 }
 438         }
 439
 440         /// Send an onion message with contents `message` to the destination of `path`.
 441         ///
 442         /// See [`OnionMessenger`] for example usage.
 443         pub fn send_onion_message<T: CustomOnionMessageContents>(
 444                 &self, path: OnionMessagePath, message: OnionMessageContents<T>,
 445                 reply_path: Option<BlindedPath>
 446         ) -> Result<(), SendError> {
 447                 let (introduction_node_id, onion_msg) = create_onion_message(
 448                         &self.entropy_source, &self.node_signer, &self.secp_ctx,
 449                         path, message, reply_path
 450                 )?;
 451
 452                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 453                 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
 454                 match pending_per_peer_msgs.entry(introduction_node_id) {
 455                         hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
 456                         hash_map::Entry::Occupied(mut e) => {
 457                                 e.get_mut().push_back(onion_msg);
 458                                 Ok(())
 459                         }
 460                 }
 461         }
 462
 463         fn respond_with_onion_message<T: CustomOnionMessageContents>(
 464                 &self, response: OnionMessageContents<T>, path_id: Option<[u8; 32]>,
 465                 reply_path: Option<BlindedPath>
 466         ) {
 467                 let sender = match self.node_signer.get_node_id(Recipient::Node) {
 468                         Ok(node_id) => node_id,
 469                         Err(_) => {
 470                                 log_warn!(
 471                                         self.logger, "Unable to retrieve node id when responding to onion message with \
 472                                         path_id {:02x?}", path_id
 473                                 );
 474                                 return;
 475                         }
 476                 };
 477
 478                 let peers = self.pending_messages.lock().unwrap().keys().copied().collect();
 479
 480                 let destination = match reply_path {
 481                         Some(reply_path) => Destination::BlindedPath(reply_path),
 482                         None => {
 483                                 log_trace!(
 484                                         self.logger, "Missing reply path when responding to onion message with path_id \
 485                                         {:02x?}", path_id
 486                                 );
 487                                 return;
 488                         },
 489                 };
 490
 491                 let path = match self.message_router.find_path(sender, peers, destination) {
 492                         Ok(path) => path,
 493                         Err(()) => {
 494                                 log_trace!(
 495                                         self.logger, "Failed to find path when responding to onion message with \
 496                                         path_id {:02x?}", path_id
 497                                 );
 498                                 return;
 499                         },
 500                 };
 501
 502                 log_trace!(self.logger, "Responding to onion message with path_id {:02x?}", path_id);
 503
 504                 if let Err(e) = self.send_onion_message(path, response, None) {
 505                         log_trace!(
 506                                 self.logger, "Failed responding to onion message with path_id {:02x?}: {:?}",
 507                                 path_id, e
 508                         );
 509                         return;
 510                 }
 511         }
 512
 513         #[cfg(test)]
 514         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
 515                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 516                 let mut msgs = HashMap::new();
 517                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 518                 // swap the pending message buffers individually.
 519                 for (peer_node_id, pending_messages) in &mut *pending_msgs {
 520                         msgs.insert(*peer_node_id, core::mem::take(pending_messages));
 521                 }
 522                 msgs
 523         }
 524 }
 525
 526 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
 527         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 528         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 529         let mut total_buffered_bytes = 0;
 530         let mut peer_buffered_bytes = 0;
 531         for (pk, peer_buf) in buffer {
 532                 for om in peer_buf {
 533                         let om_len = om.serialized_length();
 534                         if pk == peer_node_id {
 535                                 peer_buffered_bytes += om_len;
 536                         }
 537                         total_buffered_bytes += om_len;
 538
 539                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 540                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 541                         {
 542                                 return true
 543                         }
 544                 }
 545         }
 546         false
 547 }
 548
 549 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 550 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 551 where
 552         ES::Target: EntropySource,
 553         NS::Target: NodeSigner,
 554         L::Target: Logger,
 555         MR::Target: MessageRouter,
 556         OMH::Target: OffersMessageHandler,
 557         CMH::Target: CustomOnionMessageHandler,
 558 {
 559         /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
 560         /// soon we'll delegate the onion message to a handler that can generate invoices or send
 561         /// payments.
 562         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
 563                 match peel_onion(
 564                         &*self.node_signer, &self.secp_ctx, &*self.logger, &*self.custom_handler, msg
 565                 ) {
 566                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 567                                 log_trace!(self.logger,
 568                                         "Received an onion message with path_id {:02x?} and {} reply_path",
 569                                                 path_id, if reply_path.is_some() { "a" } else { "no" });
 570                                 let response = match message {
 571                                         OnionMessageContents::Offers(msg) => {
 572                                                 self.offers_handler.handle_message(msg)
 573                                                         .map(|msg| OnionMessageContents::Offers(msg))
 574                                         },
 575                                         OnionMessageContents::Custom(msg) => {
 576                                                 self.custom_handler.handle_custom_message(msg)
 577                                                         .map(|msg| OnionMessageContents::Custom(msg))
 578                                         },
 579                                 };
 580                                 if let Some(response) = response {
 581                                         self.respond_with_onion_message(response, path_id, reply_path);
 582                                 }
 583                         },
 584                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 585                                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 586                                 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
 587                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 588                                         return
 589                                 }
 590
 591                                 #[cfg(fuzzing)]
 592                                 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
 593
 594                                 match pending_per_peer_msgs.entry(next_node_id) {
 595                                         hash_map::Entry::Vacant(_) => {
 596                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 597                                                 return
 598                                         },
 599                                         hash_map::Entry::Occupied(mut e) => {
 600                                                 e.get_mut().push_back(onion_message);
 601                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 602                                         }
 603                                 }
 604                         },
 605                         Err(e) => {
 606                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
 607                         }
 608                 }
 609         }
 610
 611         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 612                 if init.features.supports_onion_messages() {
 613                         let mut peers = self.pending_messages.lock().unwrap();
 614                         peers.insert(their_node_id.clone(), VecDeque::new());
 615                 }
 616                 Ok(())
 617         }
 618
 619         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 620                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 621                 pending_msgs.remove(their_node_id);
 622         }
 623
 624         fn provided_node_features(&self) -> NodeFeatures {
 625                 let mut features = NodeFeatures::empty();
 626                 features.set_onion_messages_optional();
 627                 features
 628         }
 629
 630         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
 631                 let mut features = InitFeatures::empty();
 632                 features.set_onion_messages_optional();
 633                 features
 634         }
 635 }
 636
 637 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageProvider
 638 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 639 where
 640         ES::Target: EntropySource,
 641         NS::Target: NodeSigner,
 642         L::Target: Logger,
 643         MR::Target: MessageRouter,
 644         OMH::Target: OffersMessageHandler,
 645         CMH::Target: CustomOnionMessageHandler,
 646 {
 647         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
 648                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 649                 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
 650                         return msgs.pop_front()
 651                 }
 652                 None
 653         }
 654 }
 655
 656 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
 657 // produces
 658 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 659 /// [`SimpleArcPeerManager`]. See their docs for more details.
 660 ///
 661 /// This is not exported to bindings users as `Arc`s don't make sense in bindings.
 662 ///
 663 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 664 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
 665 pub type SimpleArcOnionMessenger<L> = OnionMessenger<
 666         Arc<KeysManager>,
 667         Arc<KeysManager>,
 668         Arc<L>,
 669         Arc<DefaultMessageRouter>,
 670         IgnoringMessageHandler,
 671         IgnoringMessageHandler
 672 >;
 673
 674 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 675 /// [`SimpleRefPeerManager`]. See their docs for more details.
 676 ///
 677 /// This is not exported to bindings users as general type aliases don't make sense in bindings.
 678 ///
 679 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 680 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
 681 pub type SimpleRefOnionMessenger<'a, 'b, 'c, L> = OnionMessenger<
 682         &'a KeysManager,
 683         &'a KeysManager,
 684         &'b L,
 685         &'c DefaultMessageRouter,
 686         IgnoringMessageHandler,
 687         IgnoringMessageHandler
 688 >;
 689
 690 /// Construct onion packet payloads and keys for sending an onion message along the given
 691 /// `unblinded_path` to the given `destination`.
 692 fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
 693         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
 694         message: OnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 695 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 696         let num_hops = unblinded_path.len() + destination.num_hops();
 697         let mut payloads = Vec::with_capacity(num_hops);
 698         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 699
 700         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
 701                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 702                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 703         let num_unblinded_hops = num_hops - num_blinded_hops;
 704
 705         let mut unblinded_path_idx = 0;
 706         let mut blinded_path_idx = 0;
 707         let mut prev_control_tlvs_ss = None;
 708         let mut final_control_tlvs = None;
 709         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
 710                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
 711                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 712                                 if let Some(ss) = prev_control_tlvs_ss.take() {
 713                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
 714                                                 ForwardTlvs {
 715                                                         next_node_id: unblinded_pk_opt.unwrap(),
 716                                                         next_blinding_override: None,
 717                                                 }
 718                                         )), ss));
 719                                 }
 720                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 721                                 unblinded_path_idx += 1;
 722                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
 723                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
 724                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 725                                                 next_node_id: intro_node_id,
 726                                                 next_blinding_override: Some(blinding_pt),
 727                                         })), control_tlvs_ss));
 728                                 }
 729                         }
 730                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
 731                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
 732                                         control_tlvs_ss));
 733                                 blinded_path_idx += 1;
 734                         } else if let Some(encrypted_payload) = enc_payload_opt {
 735                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
 736                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 737                         }
 738
 739                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
 740                         onion_packet_keys.push(onion_utils::OnionKeys {
 741                                 #[cfg(test)]
 742                                 shared_secret: onion_packet_ss,
 743                                 #[cfg(test)]
 744                                 blinding_factor: [0; 32],
 745                                 ephemeral_pubkey,
 746                                 rho,
 747                                 mu,
 748                         });
 749                 }
 750         )?;
 751
 752         if let Some(control_tlvs) = final_control_tlvs {
 753                 payloads.push((Payload::Receive {
 754                         control_tlvs,
 755                         reply_path: reply_path.take(),
 756                         message,
 757                 }, prev_control_tlvs_ss.unwrap()));
 758         } else {
 759                 payloads.push((Payload::Receive {
 760                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
 761                         reply_path: reply_path.take(),
 762                         message,
 763                 }, prev_control_tlvs_ss.unwrap()));
 764         }
 765
 766         Ok((payloads, onion_packet_keys))
 767 }
 768
 769 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
 770 fn construct_onion_message_packet<T: CustomOnionMessageContents>(payloads: Vec<(Payload<T>, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
 771         // Spec rationale:
 772         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
 773         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
 774         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
 775         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
 776         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
 777                 SMALL_PACKET_HOP_DATA_LEN
 778         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
 779                 BIG_PACKET_HOP_DATA_LEN
 780         } else { return Err(()) };
 781
 782         onion_utils::construct_onion_message_packet::<_, _>(
 783                 payloads, onion_keys, prng_seed, hop_data_len)
 784 }