_ 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::events::{Event, EventHandler, EventsProvider};
  22 use crate::sign::{EntropySource, KeysManager, NodeSigner, Recipient};
  23 #[cfg(not(c_bindings))]
  24 use crate::ln::channelmanager::{SimpleArcChannelManager, SimpleRefChannelManager};
  25 use crate::ln::features::{InitFeatures, NodeFeatures};
  26 use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler, SocketAddress};
  27 use crate::ln::onion_utils;
  28 use crate::ln::peer_handler::IgnoringMessageHandler;
  29 use crate::routing::gossip::{NetworkGraph, NodeId};
  30 pub use super::packet::OnionMessageContents;
  31 use super::packet::ParsedOnionMessageContents;
  32 use super::offers::OffersMessageHandler;
  33 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  34 use crate::util::logger::Logger;
  35 use crate::util::ser::Writeable;
  36
  37 use core::fmt;
  38 use core::ops::Deref;
  39 use crate::io;
  40 use crate::sync::{Arc, Mutex};
  41 use crate::prelude::*;
  42
  43 /// A sender, receiver and forwarder of [`OnionMessage`]s.
  44 ///
  45 /// # Handling Messages
  46 ///
  47 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
  48 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
  49 /// available handlers are:
  50 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
  51 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
  52 ///
  53 /// # Sending Messages
  54 ///
  55 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
  56 /// a message, the matched handler may return a response message which `OnionMessenger` will send
  57 /// on its behalf.
  58 ///
  59 /// # Example
  60 ///
  61 /// ```
  62 /// # extern crate bitcoin;
  63 /// # use bitcoin::hashes::_export::_core::time::Duration;
  64 /// # use bitcoin::hashes::hex::FromHex;
  65 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
  66 /// # use lightning::blinded_path::BlindedPath;
  67 /// # use lightning::sign::KeysManager;
  68 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
  69 /// # use lightning::onion_message::{OnionMessageContents, Destination, MessageRouter, OnionMessagePath, OnionMessenger};
  70 /// # use lightning::util::logger::{Logger, Record};
  71 /// # use lightning::util::ser::{Writeable, Writer};
  72 /// # use lightning::io;
  73 /// # use std::sync::Arc;
  74 /// # struct FakeLogger;
  75 /// # impl Logger for FakeLogger {
  76 /// #     fn log(&self, record: Record) { println!("{:?}" , record); }
  77 /// # }
  78 /// # struct FakeMessageRouter {}
  79 /// # impl MessageRouter for FakeMessageRouter {
  80 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
  81 /// #         let secp_ctx = Secp256k1::new();
  82 /// #         let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  83 /// #         let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  84 /// #         let hop_node_id2 = hop_node_id1;
  85 /// #         Ok(OnionMessagePath {
  86 /// #             intermediate_nodes: vec![hop_node_id1, hop_node_id2],
  87 /// #             destination,
  88 /// #             addresses: None,
  89 /// #         })
  90 /// #     }
  91 /// # }
  92 /// # let seed = [42u8; 32];
  93 /// # let time = Duration::from_secs(123456);
  94 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
  95 /// # let logger = Arc::new(FakeLogger {});
  96 /// # let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  97 /// # let secp_ctx = Secp256k1::new();
  98 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  99 /// # let (hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1);
 100 /// # let destination_node_id = hop_node_id1;
 101 /// # let message_router = Arc::new(FakeMessageRouter {});
 102 /// # let custom_message_handler = IgnoringMessageHandler {};
 103 /// # let offers_message_handler = IgnoringMessageHandler {};
 104 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
 105 /// // ChannelManager.
 106 /// let onion_messenger = OnionMessenger::new(
 107 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
 108 ///     &custom_message_handler
 109 /// );
 110
 111 /// # #[derive(Debug)]
 112 /// # struct YourCustomMessage {}
 113 /// impl Writeable for YourCustomMessage {
 114 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 115 ///             # Ok(())
 116 ///             // Write your custom onion message to `w`
 117 ///     }
 118 /// }
 119 /// impl OnionMessageContents for YourCustomMessage {
 120 ///     fn tlv_type(&self) -> u64 {
 121 ///             # let your_custom_message_type = 42;
 122 ///             your_custom_message_type
 123 ///     }
 124 /// }
 125 /// // Send a custom onion message to a node id.
 126 /// let destination = Destination::Node(destination_node_id);
 127 /// let reply_path = None;
 128 /// # let message = YourCustomMessage {};
 129 /// onion_messenger.send_onion_message(message, destination, reply_path);
 130 ///
 131 /// // Create a blinded path to yourself, for someone to send an onion message to.
 132 /// # let your_node_id = hop_node_id1;
 133 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
 134 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
 135 ///
 136 /// // Send a custom onion message to a blinded path.
 137 /// let destination = Destination::BlindedPath(blinded_path);
 138 /// let reply_path = None;
 139 /// # let message = YourCustomMessage {};
 140 /// onion_messenger.send_onion_message(message, destination, reply_path);
 141 /// ```
 142 ///
 143 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 144 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 145 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 146 where
 147         ES::Target: EntropySource,
 148         NS::Target: NodeSigner,
 149         L::Target: Logger,
 150         MR::Target: MessageRouter,
 151         OMH::Target: OffersMessageHandler,
 152         CMH:: Target: CustomOnionMessageHandler,
 153 {
 154         entropy_source: ES,
 155         node_signer: NS,
 156         logger: L,
 157         message_buffers: Mutex<HashMap<PublicKey, OnionMessageBuffer>>,
 158         secp_ctx: Secp256k1<secp256k1::All>,
 159         message_router: MR,
 160         offers_handler: OMH,
 161         custom_handler: CMH,
 162 }
 163
 164 /// [`OnionMessage`]s buffered to be sent.
 165 enum OnionMessageBuffer {
 166         /// Messages for a node connected as a peer.
 167         ConnectedPeer(VecDeque<OnionMessage>),
 168
 169         /// Messages for a node that is not yet connected.
 170         PendingConnection(VecDeque<OnionMessage>, Option<Vec<SocketAddress>>),
 171 }
 172
 173 impl OnionMessageBuffer {
 174         fn pending_messages(&self) -> &VecDeque<OnionMessage> {
 175                 match self {
 176                         OnionMessageBuffer::ConnectedPeer(pending_messages) => pending_messages,
 177                         OnionMessageBuffer::PendingConnection(pending_messages, _) => pending_messages,
 178                 }
 179         }
 180
 181         fn enqueue_message(&mut self, message: OnionMessage) {
 182                 let pending_messages = match self {
 183                         OnionMessageBuffer::ConnectedPeer(pending_messages) => pending_messages,
 184                         OnionMessageBuffer::PendingConnection(pending_messages, _) => pending_messages,
 185                 };
 186
 187                 pending_messages.push_back(message);
 188         }
 189
 190         fn dequeue_message(&mut self) -> Option<OnionMessage> {
 191                 let pending_messages = match self {
 192                         OnionMessageBuffer::ConnectedPeer(pending_messages) => pending_messages,
 193                         OnionMessageBuffer::PendingConnection(pending_messages, _) => {
 194                                 debug_assert!(false);
 195                                 pending_messages
 196                         },
 197                 };
 198
 199                 pending_messages.pop_front()
 200         }
 201
 202         #[cfg(test)]
 203         fn release_pending_messages(&mut self) -> VecDeque<OnionMessage> {
 204                 let pending_messages = match self {
 205                         OnionMessageBuffer::ConnectedPeer(pending_messages) => pending_messages,
 206                         OnionMessageBuffer::PendingConnection(pending_messages, _) => pending_messages,
 207                 };
 208
 209                 core::mem::take(pending_messages)
 210         }
 211
 212         fn mark_connected(&mut self) {
 213                 if let OnionMessageBuffer::PendingConnection(pending_messages, _) = self {
 214                         let mut new_pending_messages = VecDeque::new();
 215                         core::mem::swap(pending_messages, &mut new_pending_messages);
 216                         *self = OnionMessageBuffer::ConnectedPeer(new_pending_messages);
 217                 }
 218         }
 219 }
 220
 221 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 222 ///
 223 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 224 /// enqueued for sending.
 225 #[cfg(not(c_bindings))]
 226 pub struct PendingOnionMessage<T: OnionMessageContents> {
 227         /// The message contents to send in an [`OnionMessage`].
 228         pub contents: T,
 229
 230         /// The destination of the message.
 231         pub destination: Destination,
 232
 233         /// A reply path to include in the [`OnionMessage`] for a response.
 234         pub reply_path: Option<BlindedPath>,
 235 }
 236
 237 #[cfg(c_bindings)]
 238 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
 239 ///
 240 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
 241 /// enqueued for sending.
 242 pub type PendingOnionMessage<T: OnionMessageContents> = (T, Destination, Option<BlindedPath>);
 243
 244 pub(crate) fn new_pending_onion_message<T: OnionMessageContents>(
 245         contents: T, destination: Destination, reply_path: Option<BlindedPath>
 246 ) -> PendingOnionMessage<T> {
 247         #[cfg(not(c_bindings))]
 248         return PendingOnionMessage { contents, destination, reply_path };
 249         #[cfg(c_bindings)]
 250         return (contents, destination, reply_path);
 251 }
 252
 253 /// A trait defining behavior for routing an [`OnionMessage`].
 254 pub trait MessageRouter {
 255         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
 256         fn find_path(
 257                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 258         ) -> Result<OnionMessagePath, ()>;
 259 }
 260
 261 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
 262 pub struct DefaultMessageRouter<G: Deref<Target=NetworkGraph<L>>, L: Deref>
 263 where
 264         L::Target: Logger,
 265 {
 266         network_graph: G,
 267 }
 268
 269 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref> DefaultMessageRouter<G, L>
 270 where
 271         L::Target: Logger,
 272 {
 273         /// Creates a [`DefaultMessageRouter`] using the given [`NetworkGraph`].
 274         pub fn new(network_graph: G) -> Self {
 275                 Self { network_graph }
 276         }
 277 }
 278
 279 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref> MessageRouter for DefaultMessageRouter<G, L>
 280 where
 281         L::Target: Logger,
 282 {
 283         fn find_path(
 284                 &self, _sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
 285         ) -> Result<OnionMessagePath, ()> {
 286                 let first_node = destination.first_node();
 287                 if peers.contains(&first_node) {
 288                         Ok(OnionMessagePath { intermediate_nodes: vec![], destination, addresses: None })
 289                 } else {
 290                         let network_graph = self.network_graph.deref().read_only();
 291                         let node_announcement = network_graph
 292                                 .node(&NodeId::from_pubkey(&first_node))
 293                                 .and_then(|node_info| node_info.announcement_info.as_ref())
 294                                 .and_then(|announcement_info| announcement_info.announcement_message.as_ref())
 295                                 .map(|node_announcement| &node_announcement.contents);
 296
 297                         match node_announcement {
 298                                 Some(node_announcement) if node_announcement.features.supports_onion_messages() => {
 299                                         let addresses = Some(node_announcement.addresses.clone());
 300                                         Ok(OnionMessagePath { intermediate_nodes: vec![], destination, addresses })
 301                                 },
 302                                 _ => Err(()),
 303                         }
 304                 }
 305         }
 306 }
 307
 308 /// A path for sending an [`OnionMessage`].
 309 #[derive(Clone)]
 310 pub struct OnionMessagePath {
 311         /// Nodes on the path between the sender and the destination.
 312         pub intermediate_nodes: Vec<PublicKey>,
 313
 314         /// The recipient of the message.
 315         pub destination: Destination,
 316
 317         /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
 318         ///
 319         /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
 320         /// this to initiate such a connection.
 321         pub addresses: Option<Vec<SocketAddress>>,
 322 }
 323
 324 impl OnionMessagePath {
 325         /// Returns the first node in the path.
 326         pub fn first_node(&self) -> PublicKey {
 327                 self.intermediate_nodes
 328                         .first()
 329                         .copied()
 330                         .unwrap_or_else(|| self.destination.first_node())
 331         }
 332 }
 333
 334 /// The destination of an onion message.
 335 #[derive(Clone)]
 336 pub enum Destination {
 337         /// We're sending this onion message to a node.
 338         Node(PublicKey),
 339         /// We're sending this onion message to a blinded path.
 340         BlindedPath(BlindedPath),
 341 }
 342
 343 impl Destination {
 344         pub(super) fn num_hops(&self) -> usize {
 345                 match self {
 346                         Destination::Node(_) => 1,
 347                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
 348                 }
 349         }
 350
 351         fn first_node(&self) -> PublicKey {
 352                 match self {
 353                         Destination::Node(node_id) => *node_id,
 354                         Destination::BlindedPath(BlindedPath { introduction_node_id: node_id, .. }) => *node_id,
 355                 }
 356         }
 357 }
 358
 359 /// Result of successfully [sending an onion message].
 360 ///
 361 /// [sending an onion message]: OnionMessenger::send_onion_message
 362 #[derive(Debug, PartialEq, Eq)]
 363 pub enum SendSuccess {
 364         /// The message was buffered and will be sent once it is processed by
 365         /// [`OnionMessageHandler::next_onion_message_for_peer`].
 366         Buffered,
 367         /// The message was buffered and will be sent once the node is connected as a peer and it is
 368         /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
 369         BufferedAwaitingConnection(PublicKey),
 370 }
 371
 372 /// Errors that may occur when [sending an onion message].
 373 ///
 374 /// [sending an onion message]: OnionMessenger::send_onion_message
 375 #[derive(Debug, PartialEq, Eq)]
 376 pub enum SendError {
 377         /// Errored computing onion message packet keys.
 378         Secp256k1(secp256k1::Error),
 379         /// Because implementations such as Eclair will drop onion messages where the message packet
 380         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 381         TooBigPacket,
 382         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
 383         /// hops.
 384         TooFewBlindedHops,
 385         /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
 386         InvalidFirstHop(PublicKey),
 387         /// A path from the sender to the destination could not be found by the [`MessageRouter`].
 388         PathNotFound,
 389         /// Onion message contents must have a TLV type >= 64.
 390         InvalidMessage,
 391         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
 392         BufferFull,
 393         /// Failed to retrieve our node id from the provided [`NodeSigner`].
 394         ///
 395         /// [`NodeSigner`]: crate::sign::NodeSigner
 396         GetNodeIdFailed,
 397         /// We attempted to send to a blinded path where we are the introduction node, and failed to
 398         /// advance the blinded path to make the second hop the new introduction node. Either
 399         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
 400         /// new blinding point, or we were attempting to send to ourselves.
 401         BlindedPathAdvanceFailed,
 402 }
 403
 404 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
 405 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
 406 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
 407 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
 408 /// message types.
 409 ///
 410 /// See [`OnionMessenger`] for example usage.
 411 ///
 412 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
 413 /// [`CustomMessage`]: Self::CustomMessage
 414 pub trait CustomOnionMessageHandler {
 415         /// The message known to the handler. To support multiple message types, you may want to make this
 416         /// an enum with a variant for each supported message.
 417         type CustomMessage: OnionMessageContents;
 418
 419         /// Called with the custom message that was received, returning a response to send, if any.
 420         ///
 421         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
 422         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 423
 424         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
 425         /// message type is unknown.
 426         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
 427
 428         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 429         ///
 430         /// Typically, this is used for messages initiating a message flow rather than in response to
 431         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 432         #[cfg(not(c_bindings))]
 433         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
 434
 435         /// Releases any [`Self::CustomMessage`]s that need to be sent.
 436         ///
 437         /// Typically, this is used for messages initiating a message flow rather than in response to
 438         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
 439         #[cfg(c_bindings)]
 440         fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 441 }
 442
 443 /// A processed incoming onion message, containing either a Forward (another onion message)
 444 /// or a Receive payload with decrypted contents.
 445 pub enum PeeledOnion<T: OnionMessageContents> {
 446         /// Forwarded onion, with the next node id and a new onion
 447         Forward(PublicKey, OnionMessage),
 448         /// Received onion message, with decrypted contents, path_id, and reply path
 449         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 450 }
 451
 452 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 453 /// `path`.
 454 ///
 455 /// Returns both the node id of the peer to send the message to and the message itself.
 456 pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
 457         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
 458         path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 459 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
 460 where
 461         ES::Target: EntropySource,
 462         NS::Target: NodeSigner,
 463 {
 464         let OnionMessagePath { intermediate_nodes, mut destination, addresses } = path;
 465         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
 466                 if blinded_hops.is_empty() {
 467                         return Err(SendError::TooFewBlindedHops);
 468                 }
 469         }
 470
 471         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
 472
 473         // If we are sending straight to a blinded path and we are the introduction node, we need to
 474         // advance the blinded path by 1 hop so the second hop is the new introduction node.
 475         if intermediate_nodes.len() == 0 {
 476                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
 477                         let our_node_id = node_signer.get_node_id(Recipient::Node)
 478                                 .map_err(|()| SendError::GetNodeIdFailed)?;
 479                         if blinded_path.introduction_node_id == our_node_id {
 480                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
 481                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
 482                         }
 483                 }
 484         }
 485
 486         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 487         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 488         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
 489                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
 490         } else {
 491                 match destination {
 492                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
 493                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
 494                                 (introduction_node_id, blinding_point),
 495                 }
 496         };
 497         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 498                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret)
 499                 .map_err(|e| SendError::Secp256k1(e))?;
 500
 501         let prng_seed = entropy_source.get_secure_random_bytes();
 502         let onion_routing_packet = construct_onion_message_packet(
 503                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 504
 505         let message = OnionMessage { blinding_point, onion_routing_packet };
 506         Ok((first_node_id, message, addresses))
 507 }
 508
 509 /// Decode one layer of an incoming [`OnionMessage`].
 510 ///
 511 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
 512 /// receiver.
 513 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
 514         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
 515         custom_handler: CMH,
 516 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 517 where
 518         NS::Target: NodeSigner,
 519         L::Target: Logger,
 520         CMH::Target: CustomOnionMessageHandler,
 521 {
 522         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
 523                 Ok(ss) => ss,
 524                 Err(e) =>  {
 525                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
 526                         return Err(());
 527                 }
 528         };
 529         let onion_decode_ss = {
 530                 let blinding_factor = {
 531                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 532                         hmac.input(control_tlvs_ss.as_ref());
 533                         Hmac::from_engine(hmac).to_byte_array()
 534                 };
 535                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 536                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 537                 {
 538                         Ok(ss) => ss.secret_bytes(),
 539                         Err(()) => {
 540                                 log_trace!(logger, "Failed to compute onion packet shared secret");
 541                                 return Err(());
 542                         }
 543                 }
 544         };
 545         match onion_utils::decode_next_untagged_hop(
 546                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
 547                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
 548         ) {
 549                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
 550                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 551                 }, None)) => {
 552                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
 553                 },
 554                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 555                         next_node_id, next_blinding_override
 556                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
 557                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 558                         // blinded hop and this onion message is destined for us. In this situation, we should keep
 559                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
 560                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
 561                         // for now.
 562                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 563                                 Ok(pk) => pk,
 564                                 Err(e) => {
 565                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
 566                                         return Err(())
 567                                 }
 568                         };
 569                         let outgoing_packet = Packet {
 570                                 version: 0,
 571                                 public_key: new_pubkey,
 572                                 hop_data: new_packet_bytes,
 573                                 hmac: next_hop_hmac,
 574                         };
 575                         let onion_message = OnionMessage {
 576                                 blinding_point: match next_blinding_override {
 577                                         Some(blinding_point) => blinding_point,
 578                                         None => {
 579                                                 match onion_utils::next_hop_pubkey(
 580                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
 581                                                 ) {
 582                                                         Ok(bp) => bp,
 583                                                         Err(e) => {
 584                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
 585                                                                 return Err(())
 586                                                         }
 587                                                 }
 588                                         }
 589                                 },
 590                                 onion_routing_packet: outgoing_packet,
 591                         };
 592
 593                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
 594                 },
 595                 Err(e) => {
 596                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
 597                         Err(())
 598                 },
 599                 _ => {
 600                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 601                         Err(())
 602                 },
 603         }
 604 }
 605
 606 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
 607 OnionMessenger<ES, NS, L, MR, OMH, CMH>
 608 where
 609         ES::Target: EntropySource,
 610         NS::Target: NodeSigner,
 611         L::Target: Logger,
 612         MR::Target: MessageRouter,
 613         OMH::Target: OffersMessageHandler,
 614         CMH::Target: CustomOnionMessageHandler,
 615 {
 616         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 617         /// their respective handlers.
 618         pub fn new(
 619                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
 620                 custom_handler: CMH
 621         ) -> Self {
 622                 let mut secp_ctx = Secp256k1::new();
 623                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 624                 OnionMessenger {
 625                         entropy_source,
 626                         node_signer,
 627                         message_buffers: Mutex::new(HashMap::new()),
 628                         secp_ctx,
 629                         logger,
 630                         message_router,
 631                         offers_handler,
 632                         custom_handler,
 633                 }
 634         }
 635
 636         /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
 637         ///
 638         /// See [`OnionMessenger`] for example usage.
 639         pub fn send_onion_message<T: OnionMessageContents>(
 640                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
 641         ) -> Result<SendSuccess, SendError> {
 642                 self.find_path_and_enqueue_onion_message(
 643                         contents, destination, reply_path, format_args!("")
 644                 )
 645         }
 646
 647         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
 648                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
 649                 log_suffix: fmt::Arguments
 650         ) -> Result<SendSuccess, SendError> {
 651                 let result = self.find_path(destination)
 652                         .and_then(|path| self.enqueue_onion_message(path, contents, reply_path, log_suffix));
 653
 654                 match result.as_ref() {
 655                         Err(SendError::GetNodeIdFailed) => {
 656                                 log_warn!(self.logger, "Unable to retrieve node id {}", log_suffix);
 657                         },
 658                         Err(SendError::PathNotFound) => {
 659                                 log_trace!(self.logger, "Failed to find path {}", log_suffix);
 660                         },
 661                         Err(e) => {
 662                                 log_trace!(self.logger, "Failed sending onion message {}: {:?}", log_suffix, e);
 663                         },
 664                         Ok(SendSuccess::Buffered) => {
 665                                 log_trace!(self.logger, "Buffered onion message {}", log_suffix);
 666                         },
 667                         Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
 668                                 log_trace!(
 669                                         self.logger, "Buffered onion message waiting on peer connection {}: {:?}",
 670                                         log_suffix, node_id
 671                                 );
 672                         },
 673                 }
 674
 675                 result
 676         }
 677
 678         fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
 679                 let sender = self.node_signer
 680                         .get_node_id(Recipient::Node)
 681                         .map_err(|_| SendError::GetNodeIdFailed)?;
 682
 683                 let peers = self.message_buffers.lock().unwrap()
 684                         .iter()
 685                         .filter(|(_, buffer)| matches!(buffer, OnionMessageBuffer::ConnectedPeer(_)))
 686                         .map(|(node_id, _)| *node_id)
 687                         .collect();
 688
 689                 self.message_router
 690                         .find_path(sender, peers, destination)
 691                         .map_err(|_| SendError::PathNotFound)
 692         }
 693
 694         fn enqueue_onion_message<T: OnionMessageContents>(
 695                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 696                 log_suffix: fmt::Arguments
 697         ) -> Result<SendSuccess, SendError> {
 698                 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
 699
 700                 let (first_node_id, onion_message, addresses) = create_onion_message(
 701                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
 702                 )?;
 703
 704                 let mut message_buffers = self.message_buffers.lock().unwrap();
 705                 if outbound_buffer_full(&first_node_id, &message_buffers) {
 706                         return Err(SendError::BufferFull);
 707                 }
 708
 709                 match message_buffers.entry(first_node_id) {
 710                         hash_map::Entry::Vacant(e) => match addresses {
 711                                 None => Err(SendError::InvalidFirstHop(first_node_id)),
 712                                 Some(addresses) => {
 713                                         e.insert(
 714                                                 OnionMessageBuffer::PendingConnection(VecDeque::new(), Some(addresses))
 715                                         ).enqueue_message(onion_message);
 716                                         Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
 717                                 },
 718                         },
 719                         hash_map::Entry::Occupied(mut e) => {
 720                                 e.get_mut().enqueue_message(onion_message);
 721                                 Ok(SendSuccess::Buffered)
 722                         },
 723                 }
 724         }
 725
 726         #[cfg(test)]
 727         pub(super) fn send_onion_message_using_path<T: OnionMessageContents>(
 728                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
 729         ) -> Result<SendSuccess, SendError> {
 730                 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
 731         }
 732
 733         fn handle_onion_message_response<T: OnionMessageContents>(
 734                 &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
 735         ) {
 736                 if let Some(response) = response {
 737                         match reply_path {
 738                                 Some(reply_path) => {
 739                                         let _ = self.find_path_and_enqueue_onion_message(
 740                                                 response, Destination::BlindedPath(reply_path), None, log_suffix
 741                                         );
 742                                 },
 743                                 None => {
 744                                         log_trace!(self.logger, "Missing reply path {}", log_suffix);
 745                                 },
 746                         }
 747                 }
 748         }
 749
 750         #[cfg(test)]
 751         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
 752                 let mut message_buffers = self.message_buffers.lock().unwrap();
 753                 let mut msgs = HashMap::new();
 754                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 755                 // release the pending message buffers individually.
 756                 for (peer_node_id, buffer) in &mut *message_buffers {
 757                         msgs.insert(*peer_node_id, buffer.release_pending_messages());
 758                 }
 759                 msgs
 760         }
 761 }
 762
 763 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageBuffer>) -> bool {
 764         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
 765         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
 766         let mut total_buffered_bytes = 0;
 767         let mut peer_buffered_bytes = 0;
 768         for (pk, peer_buf) in buffer {
 769                 for om in peer_buf.pending_messages() {
 770                         let om_len = om.serialized_length();
 771                         if pk == peer_node_id {
 772                                 peer_buffered_bytes += om_len;
 773                         }
 774                         total_buffered_bytes += om_len;
 775
 776                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
 777                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
 778                         {
 779                                 return true
 780                         }
 781                 }
 782         }
 783         false
 784 }
 785
 786 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
 787 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 788 where
 789         ES::Target: EntropySource,
 790         NS::Target: NodeSigner,
 791         L::Target: Logger,
 792         MR::Target: MessageRouter,
 793         OMH::Target: OffersMessageHandler,
 794         CMH::Target: CustomOnionMessageHandler,
 795 {
 796         fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
 797                 for (node_id, recipient) in self.message_buffers.lock().unwrap().iter_mut() {
 798                         if let OnionMessageBuffer::PendingConnection(_, addresses) = recipient {
 799                                 if let Some(addresses) = addresses.take() {
 800                                         handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
 801                                 }
 802                         }
 803                 }
 804         }
 805 }
 806
 807 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
 808 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
 809 where
 810         ES::Target: EntropySource,
 811         NS::Target: NodeSigner,
 812         L::Target: Logger,
 813         MR::Target: MessageRouter,
 814         OMH::Target: OffersMessageHandler,
 815         CMH::Target: CustomOnionMessageHandler,
 816 {
 817         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
 818                 match peel_onion_message(
 819                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
 820                 ) {
 821                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
 822                                 log_trace!(
 823                                         self.logger,
 824                                    "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
 825                                         path_id, if reply_path.is_some() { "a" } else { "no" }, message);
 826
 827                                 match message {
 828                                         ParsedOnionMessageContents::Offers(msg) => {
 829                                                 let response = self.offers_handler.handle_message(msg);
 830                                                 self.handle_onion_message_response(
 831                                                         response, reply_path, format_args!(
 832                                                                 "when responding to Offers onion message with path_id {:02x?}",
 833                                                                 path_id
 834                                                         )
 835                                                 );
 836                                         },
 837                                         ParsedOnionMessageContents::Custom(msg) => {
 838                                                 let response = self.custom_handler.handle_custom_message(msg);
 839                                                 self.handle_onion_message_response(
 840                                                         response, reply_path, format_args!(
 841                                                                 "when responding to Custom onion message with path_id {:02x?}",
 842                                                                 path_id
 843                                                         )
 844                                                 );
 845                                         },
 846                                 }
 847                         },
 848                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
 849                                 let mut message_buffers = self.message_buffers.lock().unwrap();
 850                                 if outbound_buffer_full(&next_node_id, &message_buffers) {
 851                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
 852                                         return
 853                                 }
 854
 855                                 #[cfg(fuzzing)]
 856                                 message_buffers
 857                                         .entry(next_node_id)
 858                                         .or_insert_with(|| OnionMessageBuffer::ConnectedPeer(VecDeque::new()));
 859
 860                                 match message_buffers.entry(next_node_id) {
 861                                         hash_map::Entry::Occupied(mut e) if matches!(
 862                                                 e.get(), OnionMessageBuffer::ConnectedPeer(..)
 863                                         ) => {
 864                                                 e.get_mut().enqueue_message(onion_message);
 865                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 866                                         },
 867                                         _ => {
 868                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 869                                                 return
 870                                         },
 871                                 }
 872                         },
 873                         Err(e) => {
 874                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
 875                         }
 876                 }
 877         }
 878
 879         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
 880                 if init.features.supports_onion_messages() {
 881                         self.message_buffers.lock().unwrap()
 882                                 .entry(*their_node_id)
 883                                 .or_insert_with(|| OnionMessageBuffer::ConnectedPeer(VecDeque::new()))
 884                                 .mark_connected();
 885                 } else {
 886                         self.message_buffers.lock().unwrap().remove(their_node_id);
 887                 }
 888
 889                 Ok(())
 890         }
 891
 892         fn peer_disconnected(&self, their_node_id: &PublicKey) {
 893                 match self.message_buffers.lock().unwrap().remove(their_node_id) {
 894                         Some(OnionMessageBuffer::ConnectedPeer(..)) => {},
 895                         _ => debug_assert!(false),
 896                 }
 897         }
 898
 899         fn provided_node_features(&self) -> NodeFeatures {
 900                 let mut features = NodeFeatures::empty();
 901                 features.set_onion_messages_optional();
 902                 features
 903         }
 904
 905         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
 906                 let mut features = InitFeatures::empty();
 907                 features.set_onion_messages_optional();
 908                 features
 909         }
 910
 911         // Before returning any messages to send for the peer, this method will see if any messages were
 912         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
 913         // node, and then enqueue the message for sending to the first peer in the full path.
 914         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
 915                 // Enqueue any initiating `OffersMessage`s to send.
 916                 for message in self.offers_handler.release_pending_messages() {
 917                         #[cfg(not(c_bindings))]
 918                         let PendingOnionMessage { contents, destination, reply_path } = message;
 919                         #[cfg(c_bindings)]
 920                         let (contents, destination, reply_path) = message;
 921                         let _ = self.find_path_and_enqueue_onion_message(
 922                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
 923                         );
 924                 }
 925
 926                 // Enqueue any initiating `CustomMessage`s to send.
 927                 for message in self.custom_handler.release_pending_custom_messages() {
 928                         #[cfg(not(c_bindings))]
 929                         let PendingOnionMessage { contents, destination, reply_path } = message;
 930                         #[cfg(c_bindings)]
 931                         let (contents, destination, reply_path) = message;
 932                         let _ = self.find_path_and_enqueue_onion_message(
 933                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
 934                         );
 935                 }
 936
 937                 self.message_buffers.lock().unwrap()
 938                         .get_mut(&peer_node_id)
 939                         .and_then(|buffer| buffer.dequeue_message())
 940         }
 941 }
 942
 943 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
 944 // produces
 945 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 946 /// [`SimpleArcPeerManager`]. See their docs for more details.
 947 ///
 948 /// This is not exported to bindings users as type aliases aren't supported in most languages.
 949 ///
 950 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 951 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
 952 #[cfg(not(c_bindings))]
 953 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
 954         Arc<KeysManager>,
 955         Arc<KeysManager>,
 956         Arc<L>,
 957         Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>>>,
 958         Arc<SimpleArcChannelManager<M, T, F, L>>,
 959         IgnoringMessageHandler
 960 >;
 961
 962 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 963 /// [`SimpleRefPeerManager`]. See their docs for more details.
 964 ///
 965 /// This is not exported to bindings users as type aliases aren't supported in most languages.
 966 ///
 967 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 968 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
 969 #[cfg(not(c_bindings))]
 970 pub type SimpleRefOnionMessenger<
 971         'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
 972 > = OnionMessenger<
 973         &'a KeysManager,
 974         &'a KeysManager,
 975         &'b L,
 976         &'i DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L>,
 977         &'j SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
 978         IgnoringMessageHandler
 979 >;
 980
 981 /// Construct onion packet payloads and keys for sending an onion message along the given
 982 /// `unblinded_path` to the given `destination`.
 983 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
 984         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
 985         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 986 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 987         let num_hops = unblinded_path.len() + destination.num_hops();
 988         let mut payloads = Vec::with_capacity(num_hops);
 989         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 990
 991         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
 992                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 993                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 994         let num_unblinded_hops = num_hops - num_blinded_hops;
 995
 996         let mut unblinded_path_idx = 0;
 997         let mut blinded_path_idx = 0;
 998         let mut prev_control_tlvs_ss = None;
 999         let mut final_control_tlvs = None;
1000         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1001                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1002                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1003                                 if let Some(ss) = prev_control_tlvs_ss.take() {
1004                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1005                                                 ForwardTlvs {
1006                                                         next_node_id: unblinded_pk_opt.unwrap(),
1007                                                         next_blinding_override: None,
1008                                                 }
1009                                         )), ss));
1010                                 }
1011                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1012                                 unblinded_path_idx += 1;
1013                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1014                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1015                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1016                                                 next_node_id: intro_node_id,
1017                                                 next_blinding_override: Some(blinding_pt),
1018                                         })), control_tlvs_ss));
1019                                 }
1020                         }
1021                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1022                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1023                                         control_tlvs_ss));
1024                                 blinded_path_idx += 1;
1025                         } else if let Some(encrypted_payload) = enc_payload_opt {
1026                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1027                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
1028                         }
1029
1030                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1031                         onion_packet_keys.push(onion_utils::OnionKeys {
1032                                 #[cfg(test)]
1033                                 shared_secret: onion_packet_ss,
1034                                 #[cfg(test)]
1035                                 blinding_factor: [0; 32],
1036                                 ephemeral_pubkey,
1037                                 rho,
1038                                 mu,
1039                         });
1040                 }
1041         )?;
1042
1043         if let Some(control_tlvs) = final_control_tlvs {
1044                 payloads.push((Payload::Receive {
1045                         control_tlvs,
1046                         reply_path: reply_path.take(),
1047                         message,
1048                 }, prev_control_tlvs_ss.unwrap()));
1049         } else {
1050                 payloads.push((Payload::Receive {
1051                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1052                         reply_path: reply_path.take(),
1053                         message,
1054                 }, prev_control_tlvs_ss.unwrap()));
1055         }
1056
1057         Ok((payloads, onion_packet_keys))
1058 }
1059
1060 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1061 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, ()> {
1062         // Spec rationale:
1063         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1064         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1065         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1066         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1067         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1068                 SMALL_PACKET_HOP_DATA_LEN
1069         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1070                 BIG_PACKET_HOP_DATA_LEN
1071         } else { return Err(()) };
1072
1073         onion_utils::construct_onion_message_packet::<_, _>(
1074                 payloads, onion_keys, prng_seed, hop_data_len)
1075 }