git.bitcoin.ninja 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::{EntropySource, KeysManager, NodeSigner, 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 pub 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::KeysManager;
  47 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  48 /// # use lightning::onion_message::{BlindedPath, CustomOnionMessageContents, Destination, OnionMessageContents, OnionMessenger};
  49 /// # use lightning::util::logger::{Logger, Record};
  50 /// # use lightning::util::ser::{Writeable, Writer};
  51 /// # use lightning::io;
  52 /// # use std::sync::Arc;
  53 /// # struct FakeLogger;
  54 /// # impl Logger for FakeLogger {
  55 /// #     fn log(&self, record: &Record) { unimplemented!() }
  56 /// # }
  57 /// # let seed = [42u8; 32];
  58 /// # let time = Duration::from_secs(123456);
  59 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
  60 /// # let logger = Arc::new(FakeLogger {});
  61 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  62 /// # let secp_ctx = Secp256k1::new();
  63 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  64 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
  65 /// # let destination_node_id = hop_node_id1;
  66 /// # let your_custom_message_handler = IgnoringMessageHandler {};
  67 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
  68 /// // ChannelManager.
  69 /// let onion_messenger = OnionMessenger::new(&keys_manager, &keys_manager, logger, &your_custom_message_handler);
  70 ///
  71 /// # struct YourCustomMessage {}
  72 /// impl Writeable for YourCustomMessage {
  73 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  74 ///             # Ok(())
  75 ///             // Write your custom onion message to `w`
  76 ///     }
  77 /// }
  78 /// impl CustomOnionMessageContents for YourCustomMessage {
  79 ///     fn tlv_type(&self) -> u64 {
  80 ///             # let your_custom_message_type = 42;
  81 ///             your_custom_message_type
  82 ///     }
  83 /// }
  84 /// // Send a custom onion message to a node id.
  85 /// let intermediate_hops = [hop_node_id1, hop_node_id2];
  86 /// let reply_path = None;
  87 /// # let your_custom_message = YourCustomMessage {};
  88 /// let message = OnionMessageContents::Custom(your_custom_message);
  89 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::Node(destination_node_id), message, reply_path);
  90 ///
  91 /// // Create a blinded path to yourself, for someone to send an onion message to.
  92 /// # let your_node_id = hop_node_id1;
  93 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
  94 /// let blinded_path = BlindedPath::new(&hops, &keys_manager, &secp_ctx).unwrap();
  95 ///
  96 /// // Send a custom onion message to a blinded path.
  97 /// # let intermediate_hops = [hop_node_id1, hop_node_id2];
  98 /// let reply_path = None;
  99 /// # let your_custom_message = YourCustomMessage {};
 100 /// let message = OnionMessageContents::Custom(your_custom_message);
 101 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::BlindedPath(blinded_path), message, reply_path);
 102 /// ```
 103 ///
 104 /// [offers]: <https://github.com/lightning/bolts/pull/798>
 105 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
 106 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, CMH: Deref>
 107         where ES::Target: EntropySource,
 108                   NS::Target: NodeSigner,
 109                   L::Target: Logger,
 110                   CMH:: Target: CustomOnionMessageHandler,
 111 {
 112         entropy_source: ES,
 113         node_signer: NS,
 114         logger: L,
 115         pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
 116         secp_ctx: Secp256k1<secp256k1::All>,
 117         custom_handler: CMH,
 118         // Coming soon:
 119         // invoice_handler: InvoiceHandler,
 120 }
 121
 122 /// The destination of an onion message.
 123 pub enum Destination {
 124         /// We're sending this onion message to a node.
 125         Node(PublicKey),
 126         /// We're sending this onion message to a blinded path.
 127         BlindedPath(BlindedPath),
 128 }
 129
 130 impl Destination {
 131         pub(super) fn num_hops(&self) -> usize {
 132                 match self {
 133                         Destination::Node(_) => 1,
 134                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 135                 }
 136         }
 137 }
 138
 139 /// Errors that may occur when [sending an onion message].
 140 ///
 141 /// [sending an onion message]: OnionMessenger::send_onion_message
 142 #[derive(Debug, PartialEq, Eq)]
 143 pub enum SendError {
 144         /// Errored computing onion message packet keys.
 145         Secp256k1(secp256k1::Error),
 146         /// Because implementations such as Eclair will drop onion messages where the message packet
 147         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 148         TooBigPacket,
 149         /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two
 150         /// blinded hops.
 151         TooFewBlindedHops,
 152         /// Our next-hop peer was offline or does not support onion message forwarding.
 153         InvalidFirstHop,
 154         /// Onion message contents must have a TLV type >= 64.
 155         InvalidMessage,
 156         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 157         BufferFull,
 158         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 159         ///
 160         /// [`NodeSigner`]: crate::chain::keysinterface::NodeSigner
 161         GetNodeIdFailed,
 162         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 163         /// advance the blinded path to make the second hop the new introduction node. Either
 164         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 165         /// new blinding point, or we were attempting to send to ourselves.
 166         BlindedPathAdvanceFailed,
 167 }
 168
 169 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 170 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 171 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 172 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 173 /// message types.
 174 ///
 175 /// See [`OnionMessenger`] for example usage.
 176 ///
 177 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 178 /// [`CustomMessage`]: Self::CustomMessage
 179 pub trait CustomOnionMessageHandler {
 180         /// The message known to the handler. To support multiple message types, you may want to make this
 181         /// an enum with a variant for each supported message.
 182         type CustomMessage: CustomOnionMessageContents;
 183         /// Called with the custom message that was received.
 184         fn handle_custom_message(&self, msg: Self::CustomMessage);
 185         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 186         /// message type is unknown.
 187         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 188 }
 189
 190 impl<ES: Deref, NS: Deref, L: Deref, CMH: Deref> OnionMessenger<ES, NS, L, CMH>
 191         where ES::Target: EntropySource,
 192                   NS::Target: NodeSigner,
 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(entropy_source: ES, node_signer: NS, logger: L, custom_handler: CMH) -> Self {
 199                 let mut secp_ctx = Secp256k1::new();
 200                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 201                 OnionMessenger {
 202                         entropy_source,
 203                         node_signer,
 204                         pending_messages: Mutex::new(HashMap::new()),
 205                         secp_ctx,
 206                         logger,
 207                         custom_handler,
 208                 }
 209         }
 210
 211         /// Send an onion message with contents `message` to `destination`, routing it through `intermediate_nodes`.
 212         /// See [`OnionMessenger`] for example usage.
 213         pub fn send_onion_message<T: CustomOnionMessageContents>(&self, intermediate_nodes: &[PublicKey], mut destination: Destination, message: OnionMessageContents<T>, reply_path: Option<BlindedPath>) -> Result<(), SendError> {
 214                 if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 215                         if blinded_hops.len() < 2 {
 216                                 return Err(SendError::TooFewBlindedHops);
 217                         }
 218                 }
 219                 let OnionMessageContents::Custom(ref msg) = message;
 220                 if msg.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 221
 222                 // If we are sending straight to a blinded path and we are the introduction node, we need to
 223                 // advance the blinded path by 1 hop so the second hop is the new introduction node.
 224                 if intermediate_nodes.len() == 0 {
 225                         if let Destination::BlindedPath(ref mut blinded_path) = destination {
 226                                 let our_node_id = self.node_signer.get_node_id(Recipient::Node)
 227                                         .map_err(|()| SendError::GetNodeIdFailed)?;
 228                                 if blinded_path.introduction_node_id == our_node_id {
 229                                         blinded_path.advance_by_one(&self.node_signer, &self.secp_ctx)
 230                                                 .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 231                                 }
 232                         }
 233                 }
 234
 235                 let blinding_secret_bytes = self.entropy_source.get_secure_random_bytes();
 236                 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 237                 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
 238                         (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
 239                 } else {
 240                         match destination {
 241                                 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
 242                                 Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 243                                         (introduction_node_id, blinding_point),
 244                         }
 245                 };
 246                 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 247                         &self.secp_ctx, intermediate_nodes, destination, message, reply_path, &blinding_secret)
 248                         .map_err(|e| SendError::Secp256k1(e))?;
 249
 250                 let prng_seed = self.entropy_source.get_secure_random_bytes();
 251                 let onion_routing_packet = construct_onion_message_packet(
 252                         packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 253
 254                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 255                 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
 256                 match pending_per_peer_msgs.entry(introduction_node_id) {
 257                         hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
 258                         hash_map::Entry::Occupied(mut e) => {
 259                                 e.get_mut().push_back(msgs::OnionMessage { blinding_point, onion_routing_packet });
 260                                 Ok(())
 261                         }
 262                 }
 263         }
 264
 265         #[cfg(test)]
 266         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
 267                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 268                 let mut msgs = HashMap::new();
 269                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 270                 // swap the pending message buffers individually.
 271                 for (peer_node_id, pending_messages) in &mut *pending_msgs {
 272                         msgs.insert(*peer_node_id, core::mem::take(pending_messages));
 273                 }
 274                 msgs
 275         }
 276 }
 277
 278 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
 279         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 280         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 281         let mut total_buffered_bytes = 0;
 282         let mut peer_buffered_bytes = 0;
 283         for (pk, peer_buf) in buffer {
 284                 for om in peer_buf {
 285                         let om_len = om.serialized_length();
 286                         if pk == peer_node_id {
 287                                 peer_buffered_bytes += om_len;
 288                         }
 289                         total_buffered_bytes += om_len;
 290
 291                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 292                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 293                         {
 294                                 return true
 295                         }
 296                 }
 297         }
 298         false
 299 }
 300
 301 impl<ES: Deref, NS: Deref, L: Deref, CMH: Deref> OnionMessageHandler for OnionMessenger<ES, NS, L, CMH>
 302         where ES::Target: EntropySource,
 303                   NS::Target: NodeSigner,
 304                   L::Target: Logger,
 305                   CMH::Target: CustomOnionMessageHandler + Sized,
 306 {
 307         /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
 308         /// soon we'll delegate the onion message to a handler that can generate invoices or send
 309         /// payments.
 310         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
 311                 let control_tlvs_ss = match self.node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 312                         Ok(ss) => ss,
 313                         Err(e) =>  {
 314                                 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
 315                                 return
 316                         }
 317                 };
 318                 let onion_decode_ss = {
 319                         let blinding_factor = {
 320                                 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 321                                 hmac.input(control_tlvs_ss.as_ref());
 322                                 Hmac::from_engine(hmac).into_inner()
 323                         };
 324                         match self.node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 325                                 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 326                         {
 327                                 Ok(ss) => ss.secret_bytes(),
 328                                 Err(()) => {
 329                                         log_trace!(self.logger, "Failed to compute onion packet shared secret");
 330                                         return
 331                                 }
 332                         }
 333                 };
 334                 match onion_utils::decode_next_untagged_hop(onion_decode_ss, &msg.onion_routing_packet.hop_data[..],
 335                         msg.onion_routing_packet.hmac, (control_tlvs_ss, &*self.custom_handler))
 336                 {
 337                         Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
 338                                 message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 339                         }, None)) => {
 340                                 log_info!(self.logger,
 341                                         "Received an onion message with path_id {:02x?} and {} reply_path",
 342                                                 path_id, if reply_path.is_some() { "a" } else { "no" });
 343                                 match message {
 344                                         OnionMessageContents::Custom(msg) => self.custom_handler.handle_custom_message(msg),
 345                                 }
 346                         },
 347                         Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 348                                 next_node_id, next_blinding_override
 349                         })), Some((next_hop_hmac, new_packet_bytes)))) => {
 350                                 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 351                                 // blinded hop and this onion message is destined for us. In this situation, we should keep
 352                                 // unwrapping the onion layers to get to the final payload. Since we don't have the option
 353                                 // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 354                                 // for now.
 355                                 let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 356                                         Ok(pk) => pk,
 357                                         Err(e) => {
 358                                                 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
 359                                                 return
 360                                         }
 361                                 };
 362                                 let outgoing_packet = Packet {
 363                                         version: 0,
 364                                         public_key: new_pubkey,
 365                                         hop_data: new_packet_bytes,
 366                                         hmac: next_hop_hmac,
 367                                 };
 368                                 let onion_message = msgs::OnionMessage {
 369                                         blinding_point: match next_blinding_override {
 370                                                 Some(blinding_point) => blinding_point,
 371                                                 None => {
 372                                                         let blinding_factor = {
 373                                                                 let mut sha = Sha256::engine();
 374                                                                 sha.input(&msg.blinding_point.serialize()[..]);
 375                                                                 sha.input(control_tlvs_ss.as_ref());
 376                                                                 Sha256::from_engine(sha).into_inner()
 377                                                         };
 378                                                         let next_blinding_point = msg.blinding_point;
 379                                                         match next_blinding_point.mul_tweak(&self.secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) {
 380                                                                 Ok(bp) => bp,
 381                                                                 Err(e) => {
 382                                                                         log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
 383                                                                         return
 384                                                                 }
 385                                                         }
 386                                                 },
 387                                         },
 388                                         onion_routing_packet: outgoing_packet,
 389                                 };
 390
 391                                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 392                                 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
 393                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 394                                         return
 395                                 }
 396
 397                                 #[cfg(fuzzing)]
 398                                 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
 399
 400                                 match pending_per_peer_msgs.entry(next_node_id) {
 401                                         hash_map::Entry::Vacant(_) => {
 402                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 403                                                 return
 404                                         },
 405                                         hash_map::Entry::Occupied(mut e) => {
 406                                                 e.get_mut().push_back(onion_message);
 407                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 408                                         }
 409                                 };
 410                         },
 411                         Err(e) => {
 412                                 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
 413                         },
 414                         _ => {
 415                                 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 416                         },
 417                 };
 418         }
 419
 420         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 421                 if init.features.supports_onion_messages() {
 422                         let mut peers = self.pending_messages.lock().unwrap();
 423                         peers.insert(their_node_id.clone(), VecDeque::new());
 424                 }
 425                 Ok(())
 426         }
 427
 428         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 429                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 430                 pending_msgs.remove(their_node_id);
 431         }
 432
 433         fn provided_node_features(&self) -> NodeFeatures {
 434                 let mut features = NodeFeatures::empty();
 435                 features.set_onion_messages_optional();
 436                 features
 437         }
 438
 439         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
 440                 let mut features = InitFeatures::empty();
 441                 features.set_onion_messages_optional();
 442                 features
 443         }
 444 }
 445
 446 impl<ES: Deref, NS: Deref, L: Deref, CMH: Deref> OnionMessageProvider for OnionMessenger<ES, NS, L, CMH>
 447         where ES::Target: EntropySource,
 448                   NS::Target: NodeSigner,
 449                   L::Target: Logger,
 450                   CMH::Target: CustomOnionMessageHandler,
 451 {
 452         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
 453                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 454                 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
 455                         return msgs.pop_front()
 456                 }
 457                 None
 458         }
 459 }
 460
 461 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
 462 // produces
 463 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 464 /// [`SimpleArcPeerManager`]. See their docs for more details.
 465 ///
 466 /// (C-not exported) as `Arc`s don't make sense in bindings.
 467 ///
 468 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 469 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
 470 pub type SimpleArcOnionMessenger<L> = OnionMessenger<Arc<KeysManager>, Arc<KeysManager>, Arc<L>, IgnoringMessageHandler>;
 471 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 472 /// [`SimpleRefPeerManager`]. See their docs for more details.
 473 ///
 474 /// (C-not exported) as general type aliases don't make sense in bindings.
 475 ///
 476 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 477 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
 478 pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<&'a KeysManager, &'a KeysManager, &'b L, IgnoringMessageHandler>;
 479
 480 /// Construct onion packet payloads and keys for sending an onion message along the given
 481 /// `unblinded_path` to the given `destination`.
 482 fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
 483         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
 484         message: OnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 485 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 486         let num_hops = unblinded_path.len() + destination.num_hops();
 487         let mut payloads = Vec::with_capacity(num_hops);
 488         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 489
 490         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
 491                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 492                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 493         let num_unblinded_hops = num_hops - num_blinded_hops;
 494
 495         let mut unblinded_path_idx = 0;
 496         let mut blinded_path_idx = 0;
 497         let mut prev_control_tlvs_ss = None;
 498         let mut final_control_tlvs = None;
 499         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| {
 500                 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 501                         if let Some(ss) = prev_control_tlvs_ss.take() {
 502                                 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
 503                                         ForwardTlvs {
 504                                                 next_node_id: unblinded_pk_opt.unwrap(),
 505                                                 next_blinding_override: None,
 506                                         }
 507                                 )), ss));
 508                         }
 509                         prev_control_tlvs_ss = Some(control_tlvs_ss);
 510                         unblinded_path_idx += 1;
 511                 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
 512                         if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
 513                                 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 514                                         next_node_id: intro_node_id,
 515                                         next_blinding_override: Some(blinding_pt),
 516                                 })), control_tlvs_ss));
 517                         }
 518                 }
 519                 if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
 520                         payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
 521                                 control_tlvs_ss));
 522                         blinded_path_idx += 1;
 523                 } else if let Some(encrypted_payload) = enc_payload_opt {
 524                         final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
 525                         prev_control_tlvs_ss = Some(control_tlvs_ss);
 526                 }
 527
 528                 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
 529                 onion_packet_keys.push(onion_utils::OnionKeys {
 530                         #[cfg(test)]
 531                         shared_secret: onion_packet_ss,
 532                         #[cfg(test)]
 533                         blinding_factor: [0; 32],
 534                         ephemeral_pubkey,
 535                         rho,
 536                         mu,
 537                 });
 538         })?;
 539
 540         if let Some(control_tlvs) = final_control_tlvs {
 541                 payloads.push((Payload::Receive {
 542                         control_tlvs,
 543                         reply_path: reply_path.take(),
 544                         message,
 545                 }, prev_control_tlvs_ss.unwrap()));
 546         } else {
 547                 payloads.push((Payload::Receive {
 548                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
 549                         reply_path: reply_path.take(),
 550                         message,
 551                 }, prev_control_tlvs_ss.unwrap()));
 552         }
 553
 554         Ok((payloads, onion_packet_keys))
 555 }
 556
 557 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
 558 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, ()> {
 559         // Spec rationale:
 560         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
 561         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
 562         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
 563         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
 564         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
 565                 SMALL_PACKET_HOP_DATA_LEN
 566         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
 567                 BIG_PACKET_HOP_DATA_LEN
 568         } else { return Err(()) };
 569
 570         Ok(onion_utils::construct_onion_message_packet::<_, _>(
 571                 payloads, onion_keys, prng_seed, hop_data_len))
 572 }