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