_ 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 chain::keysinterface::{InMemorySigner, KeysInterface, KeysManager, Recipient, Sign};
  19 use ln::msgs::{self, OnionMessageHandler};
  20 use ln::onion_utils;
  21 use super::blinded_route::{BlindedRoute, ForwardTlvs, ReceiveTlvs};
  22 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  23 use super::utils;
  24 use util::events::OnionMessageProvider;
  25 use util::logger::Logger;
  26
  27 use core::ops::Deref;
  28 use sync::{Arc, Mutex};
  29 use prelude::*;
  30
  31 /// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be
  32 /// used to retrieve invoices and fulfill invoice requests from [offers]. Currently, only sending
  33 /// and receiving empty onion messages is supported.
  34 ///
  35 /// # Example
  36 ///
  37 /// ```
  38 /// # extern crate bitcoin;
  39 /// # use bitcoin::hashes::_export::_core::time::Duration;
  40 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
  41 /// # use lightning::chain::keysinterface::{InMemorySigner, KeysManager, KeysInterface};
  42 /// # use lightning::onion_message::{BlindedRoute, Destination, OnionMessenger};
  43 /// # use lightning::util::logger::{Logger, Record};
  44 /// # use std::sync::Arc;
  45 /// # struct FakeLogger {};
  46 /// # impl Logger for FakeLogger {
  47 /// #     fn log(&self, record: &Record) { unimplemented!() }
  48 /// # }
  49 /// # let seed = [42u8; 32];
  50 /// # let time = Duration::from_secs(123456);
  51 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
  52 /// # let logger = Arc::new(FakeLogger {});
  53 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
  54 /// # let secp_ctx = Secp256k1::new();
  55 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
  56 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1,
  57 /// hop_node_id1);
  58 /// # let destination_node_id = hop_node_id1;
  59 /// #
  60 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
  61 /// // ChannelManager.
  62 /// let onion_messenger = OnionMessenger::new(&keys_manager, logger);
  63 ///
  64 /// // Send an empty onion message to a node id.
  65 /// let intermediate_hops = [hop_node_id1, hop_node_id2];
  66 /// let reply_path = None;
  67 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::Node(destination_node_id), reply_path);
  68 ///
  69 /// // Create a blinded route to yourself, for someone to send an onion message to.
  70 /// # let your_node_id = hop_node_id1;
  71 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
  72 /// let blinded_route = BlindedRoute::new::<InMemorySigner, _, _>(&hops, &keys_manager, &secp_ctx).unwrap();
  73 ///
  74 /// // Send an empty onion message to a blinded route.
  75 /// # let intermediate_hops = [hop_node_id1, hop_node_id2];
  76 /// let reply_path = None;
  77 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::BlindedRoute(blinded_route), reply_path);
  78 /// ```
  79 ///
  80 /// [offers]: <https://github.com/lightning/bolts/pull/798>
  81 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
  82 pub struct OnionMessenger<Signer: Sign, K: Deref, L: Deref>
  83         where K::Target: KeysInterface<Signer = Signer>,
  84               L::Target: Logger,
  85 {
  86         keys_manager: K,
  87         logger: L,
  88         pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
  89         secp_ctx: Secp256k1<secp256k1::All>,
  90         // Coming soon:
  91         // invoice_handler: InvoiceHandler,
  92         // custom_handler: CustomHandler, // handles custom onion messages
  93 }
  94
  95 /// The destination of an onion message.
  96 pub enum Destination {
  97         /// We're sending this onion message to a node.
  98         Node(PublicKey),
  99         /// We're sending this onion message to a blinded route.
 100         BlindedRoute(BlindedRoute),
 101 }
 102
 103 impl Destination {
 104         pub(super) fn num_hops(&self) -> usize {
 105                 match self {
 106                         Destination::Node(_) => 1,
 107                         Destination::BlindedRoute(BlindedRoute { blinded_hops, .. }) => blinded_hops.len(),
 108                 }
 109         }
 110 }
 111
 112 /// Errors that may occur when [sending an onion message].
 113 ///
 114 /// [sending an onion message]: OnionMessenger::send_onion_message
 115 #[derive(Debug, PartialEq)]
 116 pub enum SendError {
 117         /// Errored computing onion message packet keys.
 118         Secp256k1(secp256k1::Error),
 119         /// Because implementations such as Eclair will drop onion messages where the message packet
 120         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
 121         TooBigPacket,
 122         /// The provided [`Destination`] was an invalid [`BlindedRoute`], due to having fewer than two
 123         /// blinded hops.
 124         TooFewBlindedHops,
 125         /// Our next-hop peer was offline or does not support onion message forwarding.
 126         InvalidFirstHop,
 127 }
 128
 129 impl<Signer: Sign, K: Deref, L: Deref> OnionMessenger<Signer, K, L>
 130         where K::Target: KeysInterface<Signer = Signer>,
 131               L::Target: Logger,
 132 {
 133         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
 134         /// their respective handlers.
 135         pub fn new(keys_manager: K, logger: L) -> Self {
 136                 let mut secp_ctx = Secp256k1::new();
 137                 secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
 138                 OnionMessenger {
 139                         keys_manager,
 140                         pending_messages: Mutex::new(HashMap::new()),
 141                         secp_ctx,
 142                         logger,
 143                 }
 144         }
 145
 146         /// Send an empty onion message to `destination`, routing it through `intermediate_nodes`.
 147         /// See [`OnionMessenger`] for example usage.
 148         pub fn send_onion_message(&self, intermediate_nodes: &[PublicKey], destination: Destination, reply_path: Option<BlindedRoute>) -> Result<(), SendError> {
 149                 if let Destination::BlindedRoute(BlindedRoute { ref blinded_hops, .. }) = destination {
 150                         if blinded_hops.len() < 2 {
 151                                 return Err(SendError::TooFewBlindedHops);
 152                         }
 153                 }
 154                 let blinding_secret_bytes = self.keys_manager.get_secure_random_bytes();
 155                 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 156                 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
 157                         (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
 158                 } else {
 159                         match destination {
 160                                 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
 161                                 Destination::BlindedRoute(BlindedRoute { introduction_node_id, blinding_point, .. }) =>
 162                                         (introduction_node_id, blinding_point),
 163                         }
 164                 };
 165                 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
 166                         &self.secp_ctx, intermediate_nodes, destination, reply_path, &blinding_secret)
 167                         .map_err(|e| SendError::Secp256k1(e))?;
 168
 169                 let prng_seed = self.keys_manager.get_secure_random_bytes();
 170                 let onion_routing_packet = construct_onion_message_packet(
 171                         packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
 172
 173                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 174                 match pending_per_peer_msgs.entry(introduction_node_id) {
 175                         hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
 176                         hash_map::Entry::Occupied(mut e) => {
 177                                 e.get_mut().push_back(msgs::OnionMessage { blinding_point, onion_routing_packet });
 178                                 Ok(())
 179                         }
 180                 }
 181         }
 182
 183         #[cfg(test)]
 184         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
 185                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 186                 let mut msgs = HashMap::new();
 187                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
 188                 // swap the pending message buffers individually.
 189                 for (peer_node_id, pending_messages) in &mut *pending_msgs {
 190                         msgs.insert(*peer_node_id, core::mem::take(pending_messages));
 191                 }
 192                 msgs
 193         }
 194 }
 195
 196 impl<Signer: Sign, K: Deref, L: Deref> OnionMessageHandler for OnionMessenger<Signer, K, L>
 197         where K::Target: KeysInterface<Signer = Signer>,
 198               L::Target: Logger,
 199 {
 200         /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
 201         /// soon we'll delegate the onion message to a handler that can generate invoices or send
 202         /// payments.
 203         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
 204                 let control_tlvs_ss = match self.keys_manager.ecdh(Recipient::Node, &msg.blinding_point, None) {
 205                         Ok(ss) => ss,
 206                         Err(e) =>  {
 207                                 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
 208                                 return
 209                         }
 210                 };
 211                 let onion_decode_ss = {
 212                         let blinding_factor = {
 213                                 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
 214                                 hmac.input(control_tlvs_ss.as_ref());
 215                                 Hmac::from_engine(hmac).into_inner()
 216                         };
 217                         match self.keys_manager.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
 218                                 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
 219                         {
 220                                 Ok(ss) => ss.secret_bytes(),
 221                                 Err(()) => {
 222                                         log_trace!(self.logger, "Failed to compute onion packet shared secret");
 223                                         return
 224                                 }
 225                         }
 226                 };
 227                 match onion_utils::decode_next_hop(onion_decode_ss, &msg.onion_routing_packet.hop_data[..],
 228                         msg.onion_routing_packet.hmac, control_tlvs_ss)
 229                 {
 230                         Ok((Payload::Receive {
 231                                 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
 232                         }, None)) => {
 233                                 log_info!(self.logger,
 234                                         "Received an onion message with path_id: {:02x?} and {}reply_path",
 235                                                 path_id, if reply_path.is_some() { "" } else { "no " });
 236                         },
 237                         Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 238                                 next_node_id, next_blinding_override
 239                         })), Some((next_hop_hmac, new_packet_bytes)))) => {
 240                                 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
 241                                 // blinded hop and this onion message is destined for us. In this situation, we should keep
 242                                 // unwrapping the onion layers to get to the final payload. Since we don't have the option
 243                                 // of creating blinded routes with dummy hops currently, we should be ok to not handle this
 244                                 // for now.
 245                                 let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
 246                                         Ok(pk) => pk,
 247                                         Err(e) => {
 248                                                 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
 249                                                 return
 250                                         }
 251                                 };
 252                                 let outgoing_packet = Packet {
 253                                         version: 0,
 254                                         public_key: new_pubkey,
 255                                         hop_data: new_packet_bytes,
 256                                         hmac: next_hop_hmac,
 257                                 };
 258
 259                                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
 260
 261                                 #[cfg(fuzzing)]
 262                                 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
 263
 264                                 match pending_per_peer_msgs.entry(next_node_id) {
 265                                         hash_map::Entry::Vacant(_) => {
 266                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
 267                                                 return
 268                                         },
 269                                         hash_map::Entry::Occupied(mut e) => {
 270                                                 e.get_mut().push_back(
 271                                                         msgs::OnionMessage {
 272                                                                 blinding_point: match next_blinding_override {
 273                                                                         Some(blinding_point) => blinding_point,
 274                                                                         None => {
 275                                                                                 let blinding_factor = {
 276                                                                                         let mut sha = Sha256::engine();
 277                                                                                         sha.input(&msg.blinding_point.serialize()[..]);
 278                                                                                         sha.input(control_tlvs_ss.as_ref());
 279                                                                                         Sha256::from_engine(sha).into_inner()
 280                                                                                 };
 281                                                                                 let next_blinding_point = msg.blinding_point;
 282                                                                                 match next_blinding_point.mul_tweak(&self.secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) {
 283                                                                                         Ok(bp) => bp,
 284                                                                                         Err(e) => {
 285                                                                                                 log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
 286                                                                                                 return
 287                                                                                         }
 288                                                                                 }
 289                                                                         },
 290                                                                 },
 291                                                                 onion_routing_packet: outgoing_packet,
 292                                                         },
 293                                                 );
 294                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
 295                                         }
 296                                 };
 297                         },
 298                         Err(e) => {
 299                                 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
 300                         },
 301                         _ => {
 302                                 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
 303                         },
 304                 };
 305         }
 306
 307         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init) {
 308                 if init.features.supports_onion_messages() {
 309                         let mut peers = self.pending_messages.lock().unwrap();
 310                         peers.insert(their_node_id.clone(), VecDeque::new());
 311                 }
 312         }
 313
 314         fn peer_disconnected(&self, their_node_id: &PublicKey, _no_connection_possible: bool) {
 315                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 316                 pending_msgs.remove(their_node_id);
 317         }
 318 }
 319
 320 impl<Signer: Sign, K: Deref, L: Deref> OnionMessageProvider for OnionMessenger<Signer, K, L>
 321         where K::Target: KeysInterface<Signer = Signer>,
 322               L::Target: Logger,
 323 {
 324         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
 325                 let mut pending_msgs = self.pending_messages.lock().unwrap();
 326                 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
 327                         return msgs.pop_front()
 328                 }
 329                 None
 330         }
 331 }
 332
 333 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
 334 // produces
 335 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 336 /// [`SimpleArcPeerManager`]. See their docs for more details.
 337 ///
 338 ///[`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 339 ///[`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
 340 pub type SimpleArcOnionMessenger<L> = OnionMessenger<InMemorySigner, Arc<KeysManager>, Arc<L>>;
 341 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 342 /// [`SimpleRefPeerManager`]. See their docs for more details.
 343 ///
 344 ///[`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 345 ///[`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
 346 pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<InMemorySigner, &'a KeysManager, &'b L>;
 347
 348 /// Construct onion packet payloads and keys for sending an onion message along the given
 349 /// `unblinded_path` to the given `destination`.
 350 fn packet_payloads_and_keys<T: secp256k1::Signing + secp256k1::Verification>(
 351         secp_ctx: &Secp256k1<T>, unblinded_path: &[PublicKey], destination: Destination, mut reply_path:
 352         Option<BlindedRoute>, session_priv: &SecretKey
 353 ) -> Result<(Vec<(Payload, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 354         let num_hops = unblinded_path.len() + destination.num_hops();
 355         let mut payloads = Vec::with_capacity(num_hops);
 356         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 357
 358         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedRoute(BlindedRoute {
 359                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 360                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 361         let num_unblinded_hops = num_hops - num_blinded_hops;
 362
 363         let mut unblinded_path_idx = 0;
 364         let mut blinded_path_idx = 0;
 365         let mut prev_control_tlvs_ss = None;
 366         utils::construct_keys_callback(secp_ctx, unblinded_path, Some(destination), session_priv, |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
 367                 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 368                         if let Some(ss) = prev_control_tlvs_ss.take() {
 369                                 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
 370                                         ForwardTlvs {
 371                                                 next_node_id: unblinded_pk_opt.unwrap(),
 372                                                 next_blinding_override: None,
 373                                         }
 374                                 )), ss));
 375                         }
 376                         prev_control_tlvs_ss = Some(control_tlvs_ss);
 377                         unblinded_path_idx += 1;
 378                 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
 379                         if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
 380                                 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 381                                         next_node_id: intro_node_id,
 382                                         next_blinding_override: Some(blinding_pt),
 383                                 })), control_tlvs_ss));
 384                         }
 385                         if let Some(encrypted_payload) = enc_payload_opt {
 386                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(encrypted_payload)),
 387                                         control_tlvs_ss));
 388                         } else { debug_assert!(false); }
 389                         blinded_path_idx += 1;
 390                 } else if blinded_path_idx < num_blinded_hops - 1 && enc_payload_opt.is_some() {
 391                         payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
 392                                 control_tlvs_ss));
 393                         blinded_path_idx += 1;
 394                 } else if let Some(encrypted_payload) = enc_payload_opt {
 395                         payloads.push((Payload::Receive {
 396                                 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_payload),
 397                                 reply_path: reply_path.take(),
 398                         }, control_tlvs_ss));
 399                 }
 400
 401                 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
 402                 onion_packet_keys.push(onion_utils::OnionKeys {
 403                         #[cfg(test)]
 404                         shared_secret: onion_packet_ss,
 405                         #[cfg(test)]
 406                         blinding_factor: [0; 32],
 407                         ephemeral_pubkey,
 408                         rho,
 409                         mu,
 410                 });
 411         })?;
 412
 413         if let Some(control_tlvs_ss) = prev_control_tlvs_ss {
 414                 payloads.push((Payload::Receive {
 415                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
 416                         reply_path: reply_path.take(),
 417                 }, control_tlvs_ss));
 418         }
 419
 420         Ok((payloads, onion_packet_keys))
 421 }
 422
 423 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
 424 fn construct_onion_message_packet(payloads: Vec<(Payload, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
 425         // Spec rationale:
 426         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
 427         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
 428         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
 429         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
 430         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
 431                 SMALL_PACKET_HOP_DATA_LEN
 432         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
 433                 BIG_PACKET_HOP_DATA_LEN
 434         } else { return Err(()) };
 435
 436         Ok(onion_utils::construct_onion_message_packet::<_, _>(
 437                 payloads, onion_keys, prng_seed, hop_data_len))
 438 }