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