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