_ 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::chain::keysinterface::{KeysInterface, KeysManager, Recipient};
  19 use crate::ln::features::{InitFeatures, NodeFeatures};
  20 use crate::ln::msgs::{self, OnionMessageHandler};
  21 use crate::ln::onion_utils;
  22 use crate::ln::peer_handler::IgnoringMessageHandler;
  23 use super::blinded_path::{BlindedPath, ForwardTlvs, ReceiveTlvs};
  24 use super::packet::{CustomOnionMessageContents, OnionMessageContents};
  25 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  26 use super::utils;
  27 use crate::util::events::OnionMessageProvider;
  28 use crate::util::logger::Logger;
  29 use crate::util::ser::Writeable;
  30
  31 use core::ops::Deref;
  32 use crate::io;
  33 use crate::sync::{Arc, Mutex};
  34 use crate::prelude::*;
  35
  36 /// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be
  37 /// used to retrieve invoices and fulfill invoice requests from [offers]. Currently, only sending
  38 /// and receiving custom onion messages is supported.
  39 ///
  40 /// # Example
  41 ///
  42 /// ```
  43 /// # extern crate bitcoin;
  44 /// # use bitcoin::hashes::_export::_core::time::Duration;
  45 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
  46 /// # use lightning::chain::keysinterface::{InMemorySigner, KeysManager, KeysInterface};
  47 /// # use lightning::ln::msgs::DecodeError;
  48 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  49 /// # use lightning::onion_message::blinded_path::BlindedPath;
  50 /// # use lightning::onion_message::messenger::{CustomOnionMessageContents, Destination, OnionMessageContents, OnionMessenger};
  51 /// # use lightning::util::logger::{Logger, Record};
  52 /// # use lightning::util::ser::{Writeable, Writer};
  53 /// # use lightning::io;
  54 /// # use std::sync::Arc;
  55 /// # struct FakeLogger {};
  56 /// # impl Logger for FakeLogger {
  57 /// #     fn log(&self, record: &Record) { unimplemented!() }
  58 /// # }
  59 /// # let seed = [42u8; 32];
  60 /// # let time = Duration::from_secs(123456);
  61 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
  62 /// # let logger = Arc::new(FakeLogger {});
  63 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  64 /// # let secp_ctx = Secp256k1::new();
  65 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  66 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
  67 /// # let destination_node_id = hop_node_id1;
  68 /// # let your_custom_message_handler = IgnoringMessageHandler {};
  69 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
  70 /// // ChannelManager.
  71 /// let onion_messenger = OnionMessenger::new(&keys_manager, logger, your_custom_message_handler);
  72 ///
  73 /// # #[derive(Clone)]
  74 /// # struct YourCustomMessage {}
  75 /// impl Writeable for YourCustomMessage {
  76 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  77 ///             # Ok(())
  78 ///             // Write your custom onion message to `w`
  79 ///     }
  80 /// }
  81 /// impl CustomOnionMessageContents for YourCustomMessage {
  82 ///     fn tlv_type(&self) -> u64 {
  83 ///             # let your_custom_message_type = 42;
  84 ///             your_custom_message_type
  85 ///     }
  86 /// }
  87 /// // Send a custom onion message to a node id.
  88 /// let intermediate_hops = [hop_node_id1, hop_node_id2];
  89 /// let reply_path = None;
  90 /// # let your_custom_message = YourCustomMessage {};
  91 /// let message = OnionMessageContents::Custom(your_custom_message);
  92 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::Node(destination_node_id), message, reply_path);
  93 ///
  94 /// // Create a blinded path to yourself, for someone to send an onion message to.
  95 /// # let your_node_id = hop_node_id1;
  96 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
  97 /// let blinded_path = BlindedPath::new(&hops, &keys_manager, &secp_ctx).unwrap();
  98 ///
  99 /// // Send a custom onion message to a blinded path.
 100 /// # let intermediate_hops = [hop_node_id1, hop_node_id2];
 101 /// let reply_path = None;
 102 /// # let your_custom_message = YourCustomMessage {};
 103 /// let message = OnionMessageContents::Custom(your_custom_message);
 104 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::BlindedPath(blinded_path), message, reply_path);
 105 /// ```
 106 ///
 107 /// [offers]: <https://github.com/lightning/bolts/pull/798>
 108 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
 109 pub struct OnionMessenger<K: Deref, L: Deref, CMH: Deref>
 110         where K::Target: KeysInterface,
 111               L::Target: Logger,
 112               CMH:: Target: CustomOnionMessageHandler,
 113 {
 114         keys_manager: K,
 115         logger: L,
 116         pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
 117         secp_ctx: Secp256k1<secp256k1::All>,
 118         custom_handler: CMH,
 119         // Coming soon:
 120         // invoice_handler: InvoiceHandler,
 121 }
 122
 123 /// The destination of an onion message.
 124 pub enum Destination {
 125         /// We're sending this onion message to a node.
 126         Node(PublicKey),
 127         /// We're sending this onion message to a blinded path.
 128         BlindedPath(BlindedPath),
 129 }
 130
 131 impl Destination {
 132         pub(super) fn num_hops(&self) -> usize {
 133                 match self {
 134                         Destination::Node(_) => 1,
 135                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 136                 }
 137         }
 138 }
 139
 140 /// Errors that may occur when [sending an onion message].
 141 ///
 142 /// [sending an onion message]: OnionMessenger::send_onion_message
 143 #[derive(Debug, PartialEq, Eq)]
 144 pub enum SendError {
 145         /// Errored computing onion message packet keys.
 146         Secp256k1(secp256k1::Error),
 147         /// Because implementations such as Eclair will drop onion messages where the message packet
 148         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 149         TooBigPacket,
 150         /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two
 151         /// blinded hops.
 152         TooFewBlindedHops,
 153         /// Our next-hop peer was offline or does not support onion message forwarding.
 154         InvalidFirstHop,
 155         /// Onion message contents must have a TLV type >= 64.
 156         InvalidMessage,
 157         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 158         BufferFull,
 159         /// Failed to retrieve our node id from the provided [`KeysInterface`].
 160         ///
 161         /// [`KeysInterface`]: crate::chain::keysinterface::KeysInterface
 162         GetNodeIdFailed,
 163         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 164         /// advance the blinded path to make the second hop the new introduction node. Either
 165         /// [`KeysInterface::ecdh`] failed, we failed to tweak the current blinding point to get the
 166         /// new blinding point, or we were attempting to send to ourselves.
 167         BlindedPathAdvanceFailed,
 168 }
 169
 170 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 171 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 172 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 173 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 174 /// message types.
 175 ///
 176 /// See [`OnionMessenger`] for example usage.
 177 ///
 178 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 179 /// [`CustomMessage`]: Self::CustomMessage
 180 pub trait CustomOnionMessageHandler {
 181         /// The message known to the handler. To support multiple message types, you may want to make this
 182         /// an enum with a variant for each supported message.
 183         type CustomMessage: CustomOnionMessageContents;
 184         /// Called with the custom message that was received.
 185         fn handle_custom_message(&self, msg: Self::CustomMessage);
 186         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 187         /// message type is unknown.
 188         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 189 }
 190
 191 impl<K: Deref, L: Deref, CMH: Deref> OnionMessenger<K, L, CMH>
 192         where K::Target: KeysInterface,
 193               L::Target: Logger,
 194               CMH::Target: CustomOnionMessageHandler,
 195 {
 196         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 197         /// their respective handlers.
 198         pub fn new(keys_manager: K, logger: L, custom_handler: CMH) -> Self {
 199                 let mut secp_ctx = Secp256k1::new();
 200                 secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
 201                 OnionMessenger {
 202                         keys_manager,
 203                         pending_messages: Mutex::new(HashMap::new()),
 204                         secp_ctx,
 205                         logger,
 206                         custom_handler,
 207                 }
 208         }
 209
 210         /// Send an onion message with contents `message` to `destination`, routing it through `intermediate_nodes`.
 211         /// See [`OnionMessenger`] for example usage.
 212         pub fn send_onion_message<T: CustomOnionMessageContents>(&self, intermediate_nodes: &[PublicKey], mut destination: Destination, message: OnionMessageContents<T>, reply_path: Option<BlindedPath>) -> Result<(), SendError> {
 213                 if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 214                         if blinded_hops.len() < 2 {
 215                                 return Err(SendError::TooFewBlindedHops);
 216                         }
 217                 }
 218                 let OnionMessageContents::Custom(ref msg) = message;
 219                 if msg.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 220
 221                 // If we are sending straight to a blinded path and we are the introduction node, we need to
 222                 // advance the blinded path by 1 hop so the second hop is the new introduction node.
 223                 if intermediate_nodes.len() == 0 {
 224                         if let Destination::BlindedPath(ref mut blinded_path) = destination {
 225                                 let our_node_id = self.keys_manager.get_node_id(Recipient::Node)
 226                                         .map_err(|()| SendError::GetNodeIdFailed)?;
 227                                 if blinded_path.introduction_node_id == our_node_id {
 228                                         blinded_path.advance_by_one(&self.keys_manager, &self.secp_ctx)
 229                                                 .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 230                                 }
 231                         }
 232                 }
 233
 234                 let blinding_secret_bytes = self.keys_manager.get_secure_random_bytes();
 235                 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 236                 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
 237                         (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
 238                 } else {
 239                         match destination {
 240                                 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
 241                                 Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 242                                         (introduction_node_id, blinding_point),
 243                         }
 244                 };
 245                 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 246                         &self.secp_ctx, intermediate_nodes, destination, message, reply_path, &blinding_secret)
 247                         .map_err(|e| SendError::Secp256k1(e))?;
 248
 249                 let prng_seed = self.keys_manager.get_secure_random_bytes();
 250                 let onion_routing_packet = construct_onion_message_packet(
 251                         packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 252
 253                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 254                 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
 255                 match pending_per_peer_msgs.entry(introduction_node_id) {
 256                         hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
 257                         hash_map::Entry::Occupied(mut e) => {
 258                                 e.get_mut().push_back(msgs::OnionMessage { blinding_point, onion_routing_packet });
 259                                 Ok(())
 260                         }
 261                 }
 262         }
 263
 264         #[cfg(test)]
 265         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
 266                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 267                 let mut msgs = HashMap::new();
 268                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 269                 // swap the pending message buffers individually.
 270                 for (peer_node_id, pending_messages) in &mut *pending_msgs {
 271                         msgs.insert(*peer_node_id, core::mem::take(pending_messages));
 272                 }
 273                 msgs
 274         }
 275 }
 276
 277 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
 278         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 279         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 280         let mut total_buffered_bytes = 0;
 281         let mut peer_buffered_bytes = 0;
 282         for (pk, peer_buf) in buffer {
 283                 for om in peer_buf {
 284                         let om_len = om.serialized_length();
 285                         if pk == peer_node_id {
 286                                 peer_buffered_bytes += om_len;
 287                         }
 288                         total_buffered_bytes += om_len;
 289
 290                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 291                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 292                         {
 293                                 return true
 294                         }
 295                 }
 296         }
 297         false
 298 }
 299
 300 impl<K: Deref, L: Deref, CMH: Deref> OnionMessageHandler for OnionMessenger<K, L, CMH>
 301         where K::Target: KeysInterface,
 302               L::Target: Logger,
 303               CMH::Target: CustomOnionMessageHandler + Sized,
 304 {
 305         /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
 306         /// soon we'll delegate the onion message to a handler that can generate invoices or send
 307         /// payments.
 308         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
 309                 let control_tlvs_ss = match self.keys_manager.ecdh(Recipient::Node, &msg.blinding_point, None) {
 310                         Ok(ss) => ss,
 311                         Err(e) =>  {
 312                                 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
 313                                 return
 314                         }
 315                 };
 316                 let onion_decode_ss = {
 317                         let blinding_factor = {
 318                                 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 319                                 hmac.input(control_tlvs_ss.as_ref());
 320                                 Hmac::from_engine(hmac).into_inner()
 321                         };
 322                         match self.keys_manager.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 323                                 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 324                         {
 325                                 Ok(ss) => ss.secret_bytes(),
 326                                 Err(()) => {
 327                                         log_trace!(self.logger, "Failed to compute onion packet shared secret");
 328                                         return
 329                                 }
 330                         }
 331                 };
 332                 match onion_utils::decode_next_untagged_hop(onion_decode_ss, &msg.onion_routing_packet.hop_data[..],
 333                         msg.onion_routing_packet.hmac, (control_tlvs_ss, &*self.custom_handler))
 334                 {
 335                         Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
 336                                 message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 337                         }, None)) => {
 338                                 log_info!(self.logger,
 339                                         "Received an onion message with path_id {:02x?} and {} reply_path",
 340                                                 path_id, if reply_path.is_some() { "a" } else { "no" });
 341                                 match message {
 342                                         OnionMessageContents::Custom(msg) => self.custom_handler.handle_custom_message(msg),
 343                                 }
 344                         },
 345                         Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 346                                 next_node_id, next_blinding_override
 347                         })), Some((next_hop_hmac, new_packet_bytes)))) => {
 348                                 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 349                                 // blinded hop and this onion message is destined for us. In this situation, we should keep
 350                                 // unwrapping the onion layers to get to the final payload. Since we don't have the option
 351                                 // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 352                                 // for now.
 353                                 let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 354                                         Ok(pk) => pk,
 355                                         Err(e) => {
 356                                                 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
 357                                                 return
 358                                         }
 359                                 };
 360                                 let outgoing_packet = Packet {
 361                                         version: 0,
 362                                         public_key: new_pubkey,
 363                                         hop_data: new_packet_bytes,
 364                                         hmac: next_hop_hmac,
 365                                 };
 366                                 let onion_message = msgs::OnionMessage {
 367                                         blinding_point: match next_blinding_override {
 368                                                 Some(blinding_point) => blinding_point,
 369                                                 None => {
 370                                                         let blinding_factor = {
 371                                                                 let mut sha = Sha256::engine();
 372                                                                 sha.input(&msg.blinding_point.serialize()[..]);
 373                                                                 sha.input(control_tlvs_ss.as_ref());
 374                                                                 Sha256::from_engine(sha).into_inner()
 375                                                         };
 376                                                         let next_blinding_point = msg.blinding_point;
 377                                                         match next_blinding_point.mul_tweak(&self.secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) {
 378                                                                 Ok(bp) => bp,
 379                                                                 Err(e) => {
 380                                                                         log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
 381                                                                         return
 382                                                                 }
 383                                                         }
 384                                                 },
 385                                         },
 386                                         onion_routing_packet: outgoing_packet,
 387                                 };
 388
 389                                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 390                                 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
 391                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 392                                         return
 393                                 }
 394
 395                                 #[cfg(fuzzing)]
 396                                 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
 397
 398                                 match pending_per_peer_msgs.entry(next_node_id) {
 399                                         hash_map::Entry::Vacant(_) => {
 400                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 401                                                 return
 402                                         },
 403                                         hash_map::Entry::Occupied(mut e) => {
 404                                                 e.get_mut().push_back(onion_message);
 405                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 406                                         }
 407                                 };
 408                         },
 409                         Err(e) => {
 410                                 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
 411                         },
 412                         _ => {
 413                                 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 414                         },
 415                 };
 416         }
 417
 418         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init) -> Result<(), ()> {
 419                 if init.features.supports_onion_messages() {
 420                         let mut peers = self.pending_messages.lock().unwrap();
 421                         peers.insert(their_node_id.clone(), VecDeque::new());
 422                 }
 423                 Ok(())
 424         }
 425
 426         fn peer_disconnected(&self, their_node_id: &PublicKey, _no_connection_possible: bool) {
 427                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 428                 pending_msgs.remove(their_node_id);
 429         }
 430
 431         fn provided_node_features(&self) -> NodeFeatures {
 432                 let mut features = NodeFeatures::empty();
 433                 features.set_onion_messages_optional();
 434                 features
 435         }
 436
 437         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
 438                 let mut features = InitFeatures::empty();
 439                 features.set_onion_messages_optional();
 440                 features
 441         }
 442 }
 443
 444 impl<K: Deref, L: Deref, CMH: Deref> OnionMessageProvider for OnionMessenger<K, L, CMH>
 445         where K::Target: KeysInterface,
 446               L::Target: Logger,
 447               CMH::Target: CustomOnionMessageHandler,
 448 {
 449         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
 450                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 451                 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
 452                         return msgs.pop_front()
 453                 }
 454                 None
 455         }
 456 }
 457
 458 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
 459 // produces
 460 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 461 /// [`SimpleArcPeerManager`]. See their docs for more details.
 462 ///
 463 /// (C-not exported) as `Arc`s don't make sense in bindings.
 464 ///
 465 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 466 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
 467 pub type SimpleArcOnionMessenger<L> = OnionMessenger<Arc<KeysManager>, Arc<L>, IgnoringMessageHandler>;
 468 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 469 /// [`SimpleRefPeerManager`]. See their docs for more details.
 470 ///
 471 /// (C-not exported) as general type aliases don't make sense in bindings.
 472 ///
 473 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 474 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
 475 pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<&'a KeysManager, &'b L, IgnoringMessageHandler>;
 476
 477 /// Construct onion packet payloads and keys for sending an onion message along the given
 478 /// `unblinded_path` to the given `destination`.
 479 fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
 480         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
 481         message: OnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 482 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 483         let num_hops = unblinded_path.len() + destination.num_hops();
 484         let mut payloads = Vec::with_capacity(num_hops);
 485         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 486
 487         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
 488                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 489                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 490         let num_unblinded_hops = num_hops - num_blinded_hops;
 491
 492         let mut unblinded_path_idx = 0;
 493         let mut blinded_path_idx = 0;
 494         let mut prev_control_tlvs_ss = None;
 495         let mut final_control_tlvs = None;
 496         utils::construct_keys_callback(secp_ctx, unblinded_path, Some(destination), session_priv, |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
 497                 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 498                         if let Some(ss) = prev_control_tlvs_ss.take() {
 499                                 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
 500                                         ForwardTlvs {
 501                                                 next_node_id: unblinded_pk_opt.unwrap(),
 502                                                 next_blinding_override: None,
 503                                         }
 504                                 )), ss));
 505                         }
 506                         prev_control_tlvs_ss = Some(control_tlvs_ss);
 507                         unblinded_path_idx += 1;
 508                 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
 509                         if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
 510                                 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 511                                         next_node_id: intro_node_id,
 512                                         next_blinding_override: Some(blinding_pt),
 513                                 })), control_tlvs_ss));
 514                         }
 515                 }
 516                 if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
 517                         payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
 518                                 control_tlvs_ss));
 519                         blinded_path_idx += 1;
 520                 } else if let Some(encrypted_payload) = enc_payload_opt {
 521                         final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
 522                         prev_control_tlvs_ss = Some(control_tlvs_ss);
 523                 }
 524
 525                 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
 526                 onion_packet_keys.push(onion_utils::OnionKeys {
 527                         #[cfg(test)]
 528                         shared_secret: onion_packet_ss,
 529                         #[cfg(test)]
 530                         blinding_factor: [0; 32],
 531                         ephemeral_pubkey,
 532                         rho,
 533                         mu,
 534                 });
 535         })?;
 536
 537         if let Some(control_tlvs) = final_control_tlvs {
 538                 payloads.push((Payload::Receive {
 539                         control_tlvs,
 540                         reply_path: reply_path.take(),
 541                         message,
 542                 }, prev_control_tlvs_ss.unwrap()));
 543         } else {
 544                 payloads.push((Payload::Receive {
 545                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
 546                         reply_path: reply_path.take(),
 547                         message,
 548                 }, prev_control_tlvs_ss.unwrap()));
 549         }
 550
 551         Ok((payloads, onion_packet_keys))
 552 }
 553
 554 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
 555 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, ()> {
 556         // Spec rationale:
 557         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
 558         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
 559         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
 560         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
 561         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
 562                 SMALL_PACKET_HOP_DATA_LEN
 563         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
 564                 BIG_PACKET_HOP_DATA_LEN
 565         } else { return Err(()) };
 566
 567         Ok(onion_utils::construct_onion_message_packet::<_, _>(
 568                 payloads, onion_keys, prng_seed, hop_data_len))
 569 }