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