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::blinded_path::BlindedPath;
  19 use crate::blinded_path::message::{advance_path_by_one, ForwardTlvs, ReceiveTlvs};
  20 use crate::blinded_path::utils;
  21 use crate::sign::{EntropySource, KeysManager, NodeSigner, Recipient};
  22 #[cfg(not(c_bindings))]
  23 use crate::ln::channelmanager::{SimpleArcChannelManager, SimpleRefChannelManager};
  24 use crate::ln::features::{InitFeatures, NodeFeatures};
  25 use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler, SocketAddress};
  26 use crate::ln::onion_utils;
  27 use crate::ln::peer_handler::IgnoringMessageHandler;
  28 use crate::routing::gossip::NetworkGraph;
  29 pub use super::packet::OnionMessageContents;
  30 use super::packet::ParsedOnionMessageContents;
  31 use super::offers::OffersMessageHandler;
  32 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  33 use crate::util::logger::Logger;
  34 use crate::util::ser::Writeable;
  35
  36 use core::fmt;
  37 use core::ops::Deref;
  38 use crate::io;
  39 use crate::sync::{Arc, Mutex};
  40 use crate::prelude::*;
  41
  42 /// A sender, receiver and forwarder of [`OnionMessage`]s.
  43 ///
  44 /// # Handling Messages
  45 ///
  46 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
  47 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
  48 /// available handlers are:
  49 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
  50 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
  51 ///
  52 /// # Sending Messages
  53 ///
  54 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
  55 /// a message, the matched handler may return a response message which `OnionMessenger` will send
  56 /// on its behalf.
  57 ///
  58 /// # Example
  59 ///
  60 /// ```
  61 /// # extern crate bitcoin;
  62 /// # use bitcoin::hashes::_export::_core::time::Duration;
  63 /// # use bitcoin::hashes::hex::FromHex;
  64 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
  65 /// # use lightning::blinded_path::BlindedPath;
  66 /// # use lightning::sign::KeysManager;
  67 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  68 /// # use lightning::onion_message::{OnionMessageContents, Destination, MessageRouter, OnionMessagePath, OnionMessenger};
  69 /// # use lightning::util::logger::{Logger, Record};
  70 /// # use lightning::util::ser::{Writeable, Writer};
  71 /// # use lightning::io;
  72 /// # use std::sync::Arc;
  73 /// # struct FakeLogger;
  74 /// # impl Logger for FakeLogger {
  75 /// #     fn log(&self, record: Record) { println!("{:?}" , record); }
  76 /// # }
  77 /// # struct FakeMessageRouter {}
  78 /// # impl MessageRouter for FakeMessageRouter {
  79 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  80 /// #         let secp_ctx = Secp256k1::new();
  81 /// #         let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  82 /// #         let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  83 /// #         let hop_node_id2 = hop_node_id1;
  84 /// #         Ok(OnionMessagePath {
  85 /// #             intermediate_nodes: vec![hop_node_id1, hop_node_id2],
  86 /// #             destination,
  87 /// #             addresses: None,
  88 /// #         })
  89 /// #     }
  90 /// # }
  91 /// # let seed = [42u8; 32];
  92 /// # let time = Duration::from_secs(123456);
  93 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
  94 /// # let logger = Arc::new(FakeLogger {});
  95 /// # let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  96 /// # let secp_ctx = Secp256k1::new();
  97 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  98 /// # let (hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1);
  99 /// # let destination_node_id = hop_node_id1;
 100 /// # let message_router = Arc::new(FakeMessageRouter {});
 101 /// # let custom_message_handler = IgnoringMessageHandler {};
 102 /// # let offers_message_handler = IgnoringMessageHandler {};
 103 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
 104 /// // ChannelManager.
 105 /// let onion_messenger = OnionMessenger::new(
 106 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
 107 ///     &custom_message_handler
 108 /// );
 109
 110 /// # #[derive(Debug)]
 111 /// # struct YourCustomMessage {}
 112 /// impl Writeable for YourCustomMessage {
 113 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 114 ///             # Ok(())
 115 ///             // Write your custom onion message to `w`
 116 ///     }
 117 /// }
 118 /// impl OnionMessageContents for YourCustomMessage {
 119 ///     fn tlv_type(&self) -> u64 {
 120 ///             # let your_custom_message_type = 42;
 121 ///             your_custom_message_type
 122 ///     }
 123 /// }
 124 /// // Send a custom onion message to a node id.
 125 /// let destination = Destination::Node(destination_node_id);
 126 /// let reply_path = None;
 127 /// # let message = YourCustomMessage {};
 128 /// onion_messenger.send_onion_message(message, destination, reply_path);
 129 ///
 130 /// // Create a blinded path to yourself, for someone to send an onion message to.
 131 /// # let your_node_id = hop_node_id1;
 132 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 133 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 134 ///
 135 /// // Send a custom onion message to a blinded path.
 136 /// let destination = Destination::BlindedPath(blinded_path);
 137 /// let reply_path = None;
 138 /// # let message = YourCustomMessage {};
 139 /// onion_messenger.send_onion_message(message, destination, reply_path);
 140 /// ```
 141 ///
 142 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 143 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 144 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 145 where
 146         ES::Target: EntropySource,
 147         NS::Target: NodeSigner,
 148         L::Target: Logger,
 149         MR::Target: MessageRouter,
 150         OMH::Target: OffersMessageHandler,
 151         CMH:: Target: CustomOnionMessageHandler,
 152 {
 153         entropy_source: ES,
 154         node_signer: NS,
 155         logger: L,
 156         message_buffers: Mutex<HashMap<PublicKey, OnionMessageBuffer>>,
 157         secp_ctx: Secp256k1<secp256k1::All>,
 158         message_router: MR,
 159         offers_handler: OMH,
 160         custom_handler: CMH,
 161 }
 162
 163 /// [`OnionMessage`]s buffered to be sent.
 164 enum OnionMessageBuffer {
 165         /// Messages for a node connected as a peer.
 166         ConnectedPeer(VecDeque<OnionMessage>),
 167
 168         /// Messages for a node that is not yet connected.
 169         PendingConnection(VecDeque<OnionMessage>),
 170 }
 171
 172 impl OnionMessageBuffer {
 173         fn pending_messages(&self) -> &VecDeque<OnionMessage> {
 174                 match self {
 175                         OnionMessageBuffer::ConnectedPeer(pending_messages) => pending_messages,
 176                         OnionMessageBuffer::PendingConnection(pending_messages) => pending_messages,
 177                 }
 178         }
 179
 180         fn enqueue_message(&mut self, message: OnionMessage) {
 181                 let pending_messages = match self {
 182                         OnionMessageBuffer::ConnectedPeer(pending_messages) => pending_messages,
 183                         OnionMessageBuffer::PendingConnection(pending_messages) => pending_messages,
 184                 };
 185
 186                 pending_messages.push_back(message);
 187         }
 188
 189         fn dequeue_message(&mut self) -> Option<OnionMessage> {
 190                 let pending_messages = match self {
 191                         OnionMessageBuffer::ConnectedPeer(pending_messages) => pending_messages,
 192                         OnionMessageBuffer::PendingConnection(pending_messages) => {
 193                                 debug_assert!(false);
 194                                 pending_messages
 195                         },
 196                 };
 197
 198                 pending_messages.pop_front()
 199         }
 200
 201         #[cfg(test)]
 202         fn release_pending_messages(&mut self) -> VecDeque<OnionMessage> {
 203                 let pending_messages = match self {
 204                         OnionMessageBuffer::ConnectedPeer(pending_messages) => pending_messages,
 205                         OnionMessageBuffer::PendingConnection(pending_messages) => pending_messages,
 206                 };
 207
 208                 core::mem::take(pending_messages)
 209         }
 210
 211         fn mark_connected(&mut self) {
 212                 if let OnionMessageBuffer::PendingConnection(pending_messages) = self {
 213                         let mut new_pending_messages = VecDeque::new();
 214                         core::mem::swap(pending_messages, &mut new_pending_messages);
 215                         *self = OnionMessageBuffer::ConnectedPeer(new_pending_messages);
 216                 }
 217         }
 218 }
 219
 220 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 221 ///
 222 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 223 /// enqueued for sending.
 224 #[cfg(not(c_bindings))]
 225 pub struct PendingOnionMessage<T: OnionMessageContents> {
 226         /// The message contents to send in an [`OnionMessage`].
 227         pub contents: T,
 228
 229         /// The destination of the message.
 230         pub destination: Destination,
 231
 232         /// A reply path to include in the [`OnionMessage`] for a response.
 233         pub reply_path: Option<BlindedPath>,
 234 }
 235
 236 #[cfg(c_bindings)]
 237 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 238 ///
 239 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 240 /// enqueued for sending.
 241 pub type PendingOnionMessage<T: OnionMessageContents> = (T, Destination, Option<BlindedPath>);
 242
 243 pub(crate) fn new_pending_onion_message<T: OnionMessageContents>(
 244         contents: T, destination: Destination, reply_path: Option<BlindedPath>
 245 ) -> PendingOnionMessage<T> {
 246         #[cfg(not(c_bindings))]
 247         return PendingOnionMessage { contents, destination, reply_path };
 248         #[cfg(c_bindings)]
 249         return (contents, destination, reply_path);
 250 }
 251
 252 /// A trait defining behavior for routing an [`OnionMessage`].
 253 pub trait MessageRouter {
 254         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 255         fn find_path(
 256                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 257         ) -> Result<OnionMessagePath, ()>;
 258 }
 259
 260 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
 261 pub struct DefaultMessageRouter<G: Deref<Target=NetworkGraph<L>>, L: Deref>
 262 where
 263         L::Target: Logger,
 264 {
 265         network_graph: G,
 266 }
 267
 268 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref> DefaultMessageRouter<G, L>
 269 where
 270         L::Target: Logger,
 271 {
 272         /// Creates a [`DefaultMessageRouter`] using the given [`NetworkGraph`].
 273         pub fn new(network_graph: G) -> Self {
 274                 Self { network_graph }
 275         }
 276 }
 277
 278 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref> MessageRouter for DefaultMessageRouter<G, L>
 279 where
 280         L::Target: Logger,
 281 {
 282         fn find_path(
 283                 &self, _sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 284         ) -> Result<OnionMessagePath, ()> {
 285                 if peers.contains(&destination.first_node()) {
 286                         Ok(OnionMessagePath { intermediate_nodes: vec![], destination, addresses: None })
 287                 } else {
 288                         Err(())
 289                 }
 290         }
 291 }
 292
 293 /// A path for sending an [`OnionMessage`].
 294 #[derive(Clone)]
 295 pub struct OnionMessagePath {
 296         /// Nodes on the path between the sender and the destination.
 297         pub intermediate_nodes: Vec<PublicKey>,
 298
 299         /// The recipient of the message.
 300         pub destination: Destination,
 301
 302         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 303         ///
 304         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 305         /// this to initiate such a connection.
 306         pub addresses: Option<Vec<SocketAddress>>,
 307 }
 308
 309 impl OnionMessagePath {
 310         /// Returns the first node in the path.
 311         pub fn first_node(&self) -> PublicKey {
 312                 self.intermediate_nodes
 313                         .first()
 314                         .copied()
 315                         .unwrap_or_else(|| self.destination.first_node())
 316         }
 317 }
 318
 319 /// The destination of an onion message.
 320 #[derive(Clone)]
 321 pub enum Destination {
 322         /// We're sending this onion message to a node.
 323         Node(PublicKey),
 324         /// We're sending this onion message to a blinded path.
 325         BlindedPath(BlindedPath),
 326 }
 327
 328 impl Destination {
 329         pub(super) fn num_hops(&self) -> usize {
 330                 match self {
 331                         Destination::Node(_) => 1,
 332                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 333                 }
 334         }
 335
 336         fn first_node(&self) -> PublicKey {
 337                 match self {
 338                         Destination::Node(node_id) => *node_id,
 339                         Destination::BlindedPath(BlindedPath { introduction_node_id: node_id, .. }) => *node_id,
 340                 }
 341         }
 342 }
 343
 344 /// Result of successfully [sending an onion message].
 345 ///
 346 /// [sending an onion message]: OnionMessenger::send_onion_message
 347 #[derive(Debug, PartialEq, Eq)]
 348 pub enum SendSuccess {
 349         /// The message was buffered and will be sent once it is processed by
 350         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 351         Buffered,
 352         /// The message was buffered and will be sent once the node is connected as a peer and it is
 353         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 354         BufferedAwaitingConnection(PublicKey),
 355 }
 356
 357 /// Errors that may occur when [sending an onion message].
 358 ///
 359 /// [sending an onion message]: OnionMessenger::send_onion_message
 360 #[derive(Debug, PartialEq, Eq)]
 361 pub enum SendError {
 362         /// Errored computing onion message packet keys.
 363         Secp256k1(secp256k1::Error),
 364         /// Because implementations such as Eclair will drop onion messages where the message packet
 365         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 366         TooBigPacket,
 367         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 368         /// hops.
 369         TooFewBlindedHops,
 370         /// A path from the sender to the destination could not be found by the [`MessageRouter`].
 371         PathNotFound,
 372         /// Onion message contents must have a TLV type >= 64.
 373         InvalidMessage,
 374         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 375         BufferFull,
 376         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 377         ///
 378         /// [`NodeSigner`]: crate::sign::NodeSigner
 379         GetNodeIdFailed,
 380         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 381         /// advance the blinded path to make the second hop the new introduction node. Either
 382         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 383         /// new blinding point, or we were attempting to send to ourselves.
 384         BlindedPathAdvanceFailed,
 385 }
 386
 387 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 388 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 389 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 390 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 391 /// message types.
 392 ///
 393 /// See [`OnionMessenger`] for example usage.
 394 ///
 395 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 396 /// [`CustomMessage`]: Self::CustomMessage
 397 pub trait CustomOnionMessageHandler {
 398         /// The message known to the handler. To support multiple message types, you may want to make this
 399         /// an enum with a variant for each supported message.
 400         type CustomMessage: OnionMessageContents;
 401
 402         /// Called with the custom message that was received, returning a response to send, if any.
 403         ///
 404         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 405         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 406
 407         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 408         /// message type is unknown.
 409         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 410
 411         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 412         ///
 413         /// Typically, this is used for messages initiating a message flow rather than in response to
 414         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 415         #[cfg(not(c_bindings))]
 416         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 417
 418         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 419         ///
 420         /// Typically, this is used for messages initiating a message flow rather than in response to
 421         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 422         #[cfg(c_bindings)]
 423         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 424 }
 425
 426 /// A processed incoming onion message, containing either a Forward (another onion message)
 427 /// or a Receive payload with decrypted contents.
 428 pub enum PeeledOnion<T: OnionMessageContents> {
 429         /// Forwarded onion, with the next node id and a new onion
 430         Forward(PublicKey, OnionMessage),
 431         /// Received onion message, with decrypted contents, path_id, and reply path
 432         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 433 }
 434
 435 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 436 /// `path`.
 437 ///
 438 /// Returns both the node id of the peer to send the message to and the message itself.
 439 pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
 440         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 441         path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 442 ) -> Result<(PublicKey, OnionMessage), SendError>
 443 where
 444         ES::Target: EntropySource,
 445         NS::Target: NodeSigner,
 446 {
 447         let OnionMessagePath { intermediate_nodes, mut destination, .. } = path;
 448         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 449                 if blinded_hops.is_empty() {
 450                         return Err(SendError::TooFewBlindedHops);
 451                 }
 452         }
 453
 454         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 455
 456         // If we are sending straight to a blinded path and we are the introduction node, we need to
 457         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 458         if intermediate_nodes.len() == 0 {
 459                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 460                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 461                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 462                         if blinded_path.introduction_node_id == our_node_id {
 463                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 464                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 465                         }
 466                 }
 467         }
 468
 469         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 470         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 471         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 472                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 473         } else {
 474                 match destination {
 475                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 476                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 477                                 (introduction_node_id, blinding_point),
 478                 }
 479         };
 480         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 481                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret)
 482                 .map_err(|e| SendError::Secp256k1(e))?;
 483
 484         let prng_seed = entropy_source.get_secure_random_bytes();
 485         let onion_routing_packet = construct_onion_message_packet(
 486                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 487
 488         Ok((first_node_id, OnionMessage {
 489                 blinding_point,
 490                 onion_routing_packet
 491         }))
 492 }
 493
 494 /// Decode one layer of an incoming [`OnionMessage`].
 495 ///
 496 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 497 /// receiver.
 498 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 499         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 500         custom_handler: CMH,
 501 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 502 where
 503         NS::Target: NodeSigner,
 504         L::Target: Logger,
 505         CMH::Target: CustomOnionMessageHandler,
 506 {
 507         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 508                 Ok(ss) => ss,
 509                 Err(e) =>  {
 510                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 511                         return Err(());
 512                 }
 513         };
 514         let onion_decode_ss = {
 515                 let blinding_factor = {
 516                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 517                         hmac.input(control_tlvs_ss.as_ref());
 518                         Hmac::from_engine(hmac).to_byte_array()
 519                 };
 520                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 521                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 522                 {
 523                         Ok(ss) => ss.secret_bytes(),
 524                         Err(()) => {
 525                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 526                                 return Err(());
 527                         }
 528                 }
 529         };
 530         match onion_utils::decode_next_untagged_hop(
 531                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 532                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 533         ) {
 534                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 535                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 536                 }, None)) => {
 537                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 538                 },
 539                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 540                         next_node_id, next_blinding_override
 541                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 542                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 543                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 544                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 545                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 546                         // for now.
 547                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 548                                 Ok(pk) => pk,
 549                                 Err(e) => {
 550                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 551                                         return Err(())
 552                                 }
 553                         };
 554                         let outgoing_packet = Packet {
 555                                 version: 0,
 556                                 public_key: new_pubkey,
 557                                 hop_data: new_packet_bytes,
 558                                 hmac: next_hop_hmac,
 559                         };
 560                         let onion_message = OnionMessage {
 561                                 blinding_point: match next_blinding_override {
 562                                         Some(blinding_point) => blinding_point,
 563                                         None => {
 564                                                 match onion_utils::next_hop_pubkey(
 565                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 566                                                 ) {
 567                                                         Ok(bp) => bp,
 568                                                         Err(e) => {
 569                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 570                                                                 return Err(())
 571                                                         }
 572                                                 }
 573                                         }
 574                                 },
 575                                 onion_routing_packet: outgoing_packet,
 576                         };
 577
 578                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 579                 },
 580                 Err(e) => {
 581                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 582                         Err(())
 583                 },
 584                 _ => {
 585                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 586                         Err(())
 587                 },
 588         }
 589 }
 590
 591 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 592 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 593 where
 594         ES::Target: EntropySource,
 595         NS::Target: NodeSigner,
 596         L::Target: Logger,
 597         MR::Target: MessageRouter,
 598         OMH::Target: OffersMessageHandler,
 599         CMH::Target: CustomOnionMessageHandler,
 600 {
 601         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 602         /// their respective handlers.
 603         pub fn new(
 604                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 605                 custom_handler: CMH
 606         ) -> Self {
 607                 let mut secp_ctx = Secp256k1::new();
 608                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 609                 OnionMessenger {
 610                         entropy_source,
 611                         node_signer,
 612                         message_buffers: Mutex::new(HashMap::new()),
 613                         secp_ctx,
 614                         logger,
 615                         message_router,
 616                         offers_handler,
 617                         custom_handler,
 618                 }
 619         }
 620
 621         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
 622         ///
 623         /// See [`OnionMessenger`] for example usage.
 624         pub fn send_onion_message<T: OnionMessageContents>(
 625                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
 626         ) -> Result<SendSuccess, SendError> {
 627                 self.find_path_and_enqueue_onion_message(
 628                         contents, destination, reply_path, format_args!("")
 629                 )
 630         }
 631
 632         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 633                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 634                 log_suffix: fmt::Arguments
 635         ) -> Result<SendSuccess, SendError> {
 636                 let result = self.find_path(destination)
 637                         .and_then(|path| self.enqueue_onion_message(path, contents, reply_path, log_suffix));
 638
 639                 match result.as_ref() {
 640                         Err(SendError::GetNodeIdFailed) => {
 641                                 log_warn!(self.logger, "Unable to retrieve node id {}", log_suffix);
 642                         },
 643                         Err(SendError::PathNotFound) => {
 644                                 log_trace!(self.logger, "Failed to find path {}", log_suffix);
 645                         },
 646                         Err(e) => {
 647                                 log_trace!(self.logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 648                         },
 649                         Ok(SendSuccess::Buffered) => {
 650                                 log_trace!(self.logger, "Buffered onion message {}", log_suffix);
 651                         },
 652                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
 653                                 log_trace!(
 654                                         self.logger, "Buffered onion message waiting on peer connection {}: {:?}",
 655                                         log_suffix, node_id
 656                                 );
 657                         },
 658                 }
 659
 660                 result
 661         }
 662
 663         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
 664                 let sender = self.node_signer
 665                         .get_node_id(Recipient::Node)
 666                         .map_err(|_| SendError::GetNodeIdFailed)?;
 667
 668                 let peers = self.message_buffers.lock().unwrap()
 669                         .iter()
 670                         .filter(|(_, buffer)| matches!(buffer, OnionMessageBuffer::ConnectedPeer(_)))
 671                         .map(|(node_id, _)| *node_id)
 672                         .collect();
 673
 674                 self.message_router
 675                         .find_path(sender, peers, destination)
 676                         .map_err(|_| SendError::PathNotFound)
 677         }
 678
 679         fn enqueue_onion_message<T: OnionMessageContents>(
 680                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 681                 log_suffix: fmt::Arguments
 682         ) -> Result<SendSuccess, SendError> {
 683                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 684
 685                 let (first_node_id, onion_message) = create_onion_message(
 686                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
 687                 )?;
 688
 689                 let mut message_buffers = self.message_buffers.lock().unwrap();
 690                 if outbound_buffer_full(&first_node_id, &message_buffers) {
 691                         return Err(SendError::BufferFull);
 692                 }
 693
 694                 match message_buffers.entry(first_node_id) {
 695                         hash_map::Entry::Vacant(e) => {
 696                                 e.insert(OnionMessageBuffer::PendingConnection(VecDeque::new()))
 697                                         .enqueue_message(onion_message);
 698                                 Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 699                         },
 700                         hash_map::Entry::Occupied(mut e) => {
 701                                 e.get_mut().enqueue_message(onion_message);
 702                                 Ok(SendSuccess::Buffered)
 703                         },
 704                 }
 705         }
 706
 707         #[cfg(test)]
 708         pub(super) fn send_onion_message_using_path<T: OnionMessageContents>(
 709                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
 710         ) -> Result<SendSuccess, SendError> {
 711                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
 712         }
 713
 714         fn handle_onion_message_response<T: OnionMessageContents>(
 715                 &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
 716         ) {
 717                 if let Some(response) = response {
 718                         match reply_path {
 719                                 Some(reply_path) => {
 720                                         let _ = self.find_path_and_enqueue_onion_message(
 721                                                 response, Destination::BlindedPath(reply_path), None, log_suffix
 722                                         );
 723                                 },
 724                                 None => {
 725                                         log_trace!(self.logger, "Missing reply path {}", log_suffix);
 726                                 },
 727                         }
 728                 }
 729         }
 730
 731         #[cfg(test)]
 732         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 733                 let mut message_buffers = self.message_buffers.lock().unwrap();
 734                 let mut msgs = HashMap::new();
 735                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 736                 // release the pending message buffers individually.
 737                 for (peer_node_id, buffer) in &mut *message_buffers {
 738                         msgs.insert(*peer_node_id, buffer.release_pending_messages());
 739                 }
 740                 msgs
 741         }
 742 }
 743
 744 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageBuffer>) -> bool {
 745         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 746         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 747         let mut total_buffered_bytes = 0;
 748         let mut peer_buffered_bytes = 0;
 749         for (pk, peer_buf) in buffer {
 750                 for om in peer_buf.pending_messages() {
 751                         let om_len = om.serialized_length();
 752                         if pk == peer_node_id {
 753                                 peer_buffered_bytes += om_len;
 754                         }
 755                         total_buffered_bytes += om_len;
 756
 757                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 758                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 759                         {
 760                                 return true
 761                         }
 762                 }
 763         }
 764         false
 765 }
 766
 767 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 768 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 769 where
 770         ES::Target: EntropySource,
 771         NS::Target: NodeSigner,
 772         L::Target: Logger,
 773         MR::Target: MessageRouter,
 774         OMH::Target: OffersMessageHandler,
 775         CMH::Target: CustomOnionMessageHandler,
 776 {
 777         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
 778                 match peel_onion_message(
 779                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
 780                 ) {
 781                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 782                                 log_trace!(
 783                                         self.logger,
 784                                    "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
 785                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
 786
 787                                 match message {
 788                                         ParsedOnionMessageContents::Offers(msg) => {
 789                                                 let response = self.offers_handler.handle_message(msg);
 790                                                 self.handle_onion_message_response(
 791                                                         response, reply_path, format_args!(
 792                                                                 "when responding to Offers onion message with path_id {:02x?}",
 793                                                                 path_id
 794                                                         )
 795                                                 );
 796                                         },
 797                                         ParsedOnionMessageContents::Custom(msg) => {
 798                                                 let response = self.custom_handler.handle_custom_message(msg);
 799                                                 self.handle_onion_message_response(
 800                                                         response, reply_path, format_args!(
 801                                                                 "when responding to Custom onion message with path_id {:02x?}",
 802                                                                 path_id
 803                                                         )
 804                                                 );
 805                                         },
 806                                 }
 807                         },
 808                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 809                                 let mut message_buffers = self.message_buffers.lock().unwrap();
 810                                 if outbound_buffer_full(&next_node_id, &message_buffers) {
 811                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 812                                         return
 813                                 }
 814
 815                                 #[cfg(fuzzing)]
 816                                 message_buffers
 817                                         .entry(next_node_id)
 818                                         .or_insert_with(|| OnionMessageBuffer::ConnectedPeer(VecDeque::new()));
 819
 820                                 match message_buffers.entry(next_node_id) {
 821                                         hash_map::Entry::Occupied(mut e) if matches!(
 822                                                 e.get(), OnionMessageBuffer::ConnectedPeer(..)
 823                                         ) => {
 824                                                 e.get_mut().enqueue_message(onion_message);
 825                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 826                                         },
 827                                         _ => {
 828                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 829                                                 return
 830                                         },
 831                                 }
 832                         },
 833                         Err(e) => {
 834                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
 835                         }
 836                 }
 837         }
 838
 839         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 840                 if init.features.supports_onion_messages() {
 841                         self.message_buffers.lock().unwrap()
 842                                 .entry(*their_node_id)
 843                                 .or_insert_with(|| OnionMessageBuffer::ConnectedPeer(VecDeque::new()))
 844                                 .mark_connected();
 845                 } else {
 846                         self.message_buffers.lock().unwrap().remove(their_node_id);
 847                 }
 848
 849                 Ok(())
 850         }
 851
 852         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 853                 match self.message_buffers.lock().unwrap().remove(their_node_id) {
 854                         Some(OnionMessageBuffer::ConnectedPeer(..)) => {},
 855                         _ => debug_assert!(false),
 856                 }
 857         }
 858
 859         fn provided_node_features(&self) -> NodeFeatures {
 860                 let mut features = NodeFeatures::empty();
 861                 features.set_onion_messages_optional();
 862                 features
 863         }
 864
 865         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
 866                 let mut features = InitFeatures::empty();
 867                 features.set_onion_messages_optional();
 868                 features
 869         }
 870
 871         // Before returning any messages to send for the peer, this method will see if any messages were
 872         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
 873         // node, and then enqueue the message for sending to the first peer in the full path.
 874         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
 875                 // Enqueue any initiating `OffersMessage`s to send.
 876                 for message in self.offers_handler.release_pending_messages() {
 877                         #[cfg(not(c_bindings))]
 878                         let PendingOnionMessage { contents, destination, reply_path } = message;
 879                         #[cfg(c_bindings)]
 880                         let (contents, destination, reply_path) = message;
 881                         let _ = self.find_path_and_enqueue_onion_message(
 882                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
 883                         );
 884                 }
 885
 886                 // Enqueue any initiating `CustomMessage`s to send.
 887                 for message in self.custom_handler.release_pending_custom_messages() {
 888                         #[cfg(not(c_bindings))]
 889                         let PendingOnionMessage { contents, destination, reply_path } = message;
 890                         #[cfg(c_bindings)]
 891                         let (contents, destination, reply_path) = message;
 892                         let _ = self.find_path_and_enqueue_onion_message(
 893                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
 894                         );
 895                 }
 896
 897                 self.message_buffers.lock().unwrap()
 898                         .get_mut(&peer_node_id)
 899                         .and_then(|buffer| buffer.dequeue_message())
 900         }
 901 }
 902
 903 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
 904 // produces
 905 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 906 /// [`SimpleArcPeerManager`]. See their docs for more details.
 907 ///
 908 /// This is not exported to bindings users as type aliases aren't supported in most languages.
 909 ///
 910 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 911 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
 912 #[cfg(not(c_bindings))]
 913 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
 914         Arc<KeysManager>,
 915         Arc<KeysManager>,
 916         Arc<L>,
 917         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>>>,
 918         Arc<SimpleArcChannelManager<M, T, F, L>>,
 919         IgnoringMessageHandler
 920 >;
 921
 922 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 923 /// [`SimpleRefPeerManager`]. See their docs for more details.
 924 ///
 925 /// This is not exported to bindings users as type aliases aren't supported in most languages.
 926 ///
 927 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 928 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
 929 #[cfg(not(c_bindings))]
 930 pub type SimpleRefOnionMessenger<
 931         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
 932 > = OnionMessenger<
 933         &'a KeysManager,
 934         &'a KeysManager,
 935         &'b L,
 936         &'i DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L>,
 937         &'j SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
 938         IgnoringMessageHandler
 939 >;
 940
 941 /// Construct onion packet payloads and keys for sending an onion message along the given
 942 /// `unblinded_path` to the given `destination`.
 943 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
 944         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
 945         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 946 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 947         let num_hops = unblinded_path.len() + destination.num_hops();
 948         let mut payloads = Vec::with_capacity(num_hops);
 949         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 950
 951         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
 952                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 953                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 954         let num_unblinded_hops = num_hops - num_blinded_hops;
 955
 956         let mut unblinded_path_idx = 0;
 957         let mut blinded_path_idx = 0;
 958         let mut prev_control_tlvs_ss = None;
 959         let mut final_control_tlvs = None;
 960         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
 961                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
 962                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 963                                 if let Some(ss) = prev_control_tlvs_ss.take() {
 964                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
 965                                                 ForwardTlvs {
 966                                                         next_node_id: unblinded_pk_opt.unwrap(),
 967                                                         next_blinding_override: None,
 968                                                 }
 969                                         )), ss));
 970                                 }
 971                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 972                                 unblinded_path_idx += 1;
 973                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
 974                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
 975                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 976                                                 next_node_id: intro_node_id,
 977                                                 next_blinding_override: Some(blinding_pt),
 978                                         })), control_tlvs_ss));
 979                                 }
 980                         }
 981                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
 982                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
 983                                         control_tlvs_ss));
 984                                 blinded_path_idx += 1;
 985                         } else if let Some(encrypted_payload) = enc_payload_opt {
 986                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
 987                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
 988                         }
 989
 990                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
 991                         onion_packet_keys.push(onion_utils::OnionKeys {
 992                                 #[cfg(test)]
 993                                 shared_secret: onion_packet_ss,
 994                                 #[cfg(test)]
 995                                 blinding_factor: [0; 32],
 996                                 ephemeral_pubkey,
 997                                 rho,
 998                                 mu,
 999                         });
1000                 }
1001         )?;
1002
1003         if let Some(control_tlvs) = final_control_tlvs {
1004                 payloads.push((Payload::Receive {
1005                         control_tlvs,
1006                         reply_path: reply_path.take(),
1007                         message,
1008                 }, prev_control_tlvs_ss.unwrap()));
1009         } else {
1010                 payloads.push((Payload::Receive {
1011                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1012                         reply_path: reply_path.take(),
1013                         message,
1014                 }, prev_control_tlvs_ss.unwrap()));
1015         }
1016
1017         Ok((payloads, onion_packet_keys))
1018 }
1019
1020 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1021 fn construct_onion_message_packet<T: OnionMessageContents>(payloads: Vec<(Payload<T>, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
1022         // Spec rationale:
1023         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1024         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1025         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1026         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1027         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1028                 SMALL_PACKET_HOP_DATA_LEN
1029         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1030                 BIG_PACKET_HOP_DATA_LEN
1031         } else { return Err(()) };
1032
1033         onion_utils::construct_onion_message_packet::<_, _>(
1034                 payloads, onion_keys, prng_seed, hop_data_len)
1035 }