1 // This file is Copyright its original authors, visible in version control
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
10 //! LDK sends, receives, and forwards onion messages via the [`OnionMessenger`]. See its docs for
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};
18 use chain::keysinterface::{InMemorySigner, KeysInterface, KeysManager, Recipient, Sign};
19 use ln::features::{InitFeatures, NodeFeatures};
20 use ln::msgs::{self, OnionMessageHandler};
22 use super::blinded_route::{BlindedRoute, ForwardTlvs, ReceiveTlvs};
23 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
25 use util::events::OnionMessageProvider;
26 use util::logger::Logger;
27 use util::ser::Writeable;
30 use sync::{Arc, Mutex};
33 /// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be
34 /// used to retrieve invoices and fulfill invoice requests from [offers]. Currently, only sending
35 /// and receiving empty onion messages is supported.
40 /// # extern crate bitcoin;
41 /// # use bitcoin::hashes::_export::_core::time::Duration;
42 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
43 /// # use lightning::chain::keysinterface::{InMemorySigner, KeysManager, KeysInterface};
44 /// # use lightning::onion_message::messenger::{Destination, OnionMessenger};
45 /// # use lightning::onion_message::blinded_route::BlindedRoute;
46 /// # use lightning::util::logger::{Logger, Record};
47 /// # use std::sync::Arc;
48 /// # struct FakeLogger {};
49 /// # impl Logger for FakeLogger {
50 /// # fn log(&self, record: &Record) { unimplemented!() }
52 /// # let seed = [42u8; 32];
53 /// # let time = Duration::from_secs(123456);
54 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
55 /// # let logger = Arc::new(FakeLogger {});
56 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
57 /// # let secp_ctx = Secp256k1::new();
58 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
59 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1,
61 /// # let destination_node_id = hop_node_id1;
63 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
64 /// // ChannelManager.
65 /// let onion_messenger = OnionMessenger::new(&keys_manager, logger);
67 /// // Send an empty onion message to a node id.
68 /// let intermediate_hops = [hop_node_id1, hop_node_id2];
69 /// let reply_path = None;
70 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::Node(destination_node_id), reply_path);
72 /// // Create a blinded route to yourself, for someone to send an onion message to.
73 /// # let your_node_id = hop_node_id1;
74 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
75 /// let blinded_route = BlindedRoute::new(&hops, &keys_manager, &secp_ctx).unwrap();
77 /// // Send an empty onion message to a blinded route.
78 /// # let intermediate_hops = [hop_node_id1, hop_node_id2];
79 /// let reply_path = None;
80 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::BlindedRoute(blinded_route), reply_path);
83 /// [offers]: <https://github.com/lightning/bolts/pull/798>
84 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
85 pub struct OnionMessenger<Signer: Sign, K: Deref, L: Deref>
86 where K::Target: KeysInterface<Signer = Signer>,
91 pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
92 secp_ctx: Secp256k1<secp256k1::All>,
94 // invoice_handler: InvoiceHandler,
95 // custom_handler: CustomHandler, // handles custom onion messages
98 /// The destination of an onion message.
99 pub enum Destination {
100 /// We're sending this onion message to a node.
102 /// We're sending this onion message to a blinded route.
103 BlindedRoute(BlindedRoute),
107 pub(super) fn num_hops(&self) -> usize {
109 Destination::Node(_) => 1,
110 Destination::BlindedRoute(BlindedRoute { blinded_hops, .. }) => blinded_hops.len(),
115 /// Errors that may occur when [sending an onion message].
117 /// [sending an onion message]: OnionMessenger::send_onion_message
118 #[derive(Debug, PartialEq)]
120 /// Errored computing onion message packet keys.
121 Secp256k1(secp256k1::Error),
122 /// Because implementations such as Eclair will drop onion messages where the message packet
123 /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
125 /// The provided [`Destination`] was an invalid [`BlindedRoute`], due to having fewer than two
128 /// Our next-hop peer was offline or does not support onion message forwarding.
130 /// Our next-hop peer's buffer was full or our total outbound buffer was full.
134 impl<Signer: Sign, K: Deref, L: Deref> OnionMessenger<Signer, K, L>
135 where K::Target: KeysInterface<Signer = Signer>,
138 /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
139 /// their respective handlers.
140 pub fn new(keys_manager: K, logger: L) -> Self {
141 let mut secp_ctx = Secp256k1::new();
142 secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
145 pending_messages: Mutex::new(HashMap::new()),
151 /// Send an empty onion message to `destination`, routing it through `intermediate_nodes`.
152 /// See [`OnionMessenger`] for example usage.
153 pub fn send_onion_message(&self, intermediate_nodes: &[PublicKey], destination: Destination, reply_path: Option<BlindedRoute>) -> Result<(), SendError> {
154 if let Destination::BlindedRoute(BlindedRoute { ref blinded_hops, .. }) = destination {
155 if blinded_hops.len() < 2 {
156 return Err(SendError::TooFewBlindedHops);
159 let blinding_secret_bytes = self.keys_manager.get_secure_random_bytes();
160 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
161 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
162 (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
165 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
166 Destination::BlindedRoute(BlindedRoute { introduction_node_id, blinding_point, .. }) =>
167 (introduction_node_id, blinding_point),
170 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
171 &self.secp_ctx, intermediate_nodes, destination, reply_path, &blinding_secret)
172 .map_err(|e| SendError::Secp256k1(e))?;
174 let prng_seed = self.keys_manager.get_secure_random_bytes();
175 let onion_routing_packet = construct_onion_message_packet(
176 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
178 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
179 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
180 match pending_per_peer_msgs.entry(introduction_node_id) {
181 hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
182 hash_map::Entry::Occupied(mut e) => {
183 e.get_mut().push_back(msgs::OnionMessage { blinding_point, onion_routing_packet });
190 pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
191 let mut pending_msgs = self.pending_messages.lock().unwrap();
192 let mut msgs = HashMap::new();
193 // We don't want to disconnect the peers by removing them entirely from the original map, so we
194 // swap the pending message buffers individually.
195 for (peer_node_id, pending_messages) in &mut *pending_msgs {
196 msgs.insert(*peer_node_id, core::mem::take(pending_messages));
202 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
203 const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
204 const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
205 let mut total_buffered_bytes = 0;
206 let mut peer_buffered_bytes = 0;
207 for (pk, peer_buf) in buffer {
209 let om_len = om.serialized_length();
210 if pk == peer_node_id {
211 peer_buffered_bytes += om_len;
213 total_buffered_bytes += om_len;
215 if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
216 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
225 impl<Signer: Sign, K: Deref, L: Deref> OnionMessageHandler for OnionMessenger<Signer, K, L>
226 where K::Target: KeysInterface<Signer = Signer>,
229 /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
230 /// soon we'll delegate the onion message to a handler that can generate invoices or send
232 fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
233 let control_tlvs_ss = match self.keys_manager.ecdh(Recipient::Node, &msg.blinding_point, None) {
236 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
240 let onion_decode_ss = {
241 let blinding_factor = {
242 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
243 hmac.input(control_tlvs_ss.as_ref());
244 Hmac::from_engine(hmac).into_inner()
246 match self.keys_manager.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
247 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
249 Ok(ss) => ss.secret_bytes(),
251 log_trace!(self.logger, "Failed to compute onion packet shared secret");
256 match onion_utils::decode_next_hop(onion_decode_ss, &msg.onion_routing_packet.hop_data[..],
257 msg.onion_routing_packet.hmac, control_tlvs_ss)
259 Ok((Payload::Receive {
260 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
262 log_info!(self.logger,
263 "Received an onion message with path_id: {:02x?} and {}reply_path",
264 path_id, if reply_path.is_some() { "" } else { "no " });
266 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
267 next_node_id, next_blinding_override
268 })), Some((next_hop_hmac, new_packet_bytes)))) => {
269 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
270 // blinded hop and this onion message is destined for us. In this situation, we should keep
271 // unwrapping the onion layers to get to the final payload. Since we don't have the option
272 // of creating blinded routes with dummy hops currently, we should be ok to not handle this
274 let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
277 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
281 let outgoing_packet = Packet {
283 public_key: new_pubkey,
284 hop_data: new_packet_bytes,
287 let onion_message = msgs::OnionMessage {
288 blinding_point: match next_blinding_override {
289 Some(blinding_point) => blinding_point,
291 let blinding_factor = {
292 let mut sha = Sha256::engine();
293 sha.input(&msg.blinding_point.serialize()[..]);
294 sha.input(control_tlvs_ss.as_ref());
295 Sha256::from_engine(sha).into_inner()
297 let next_blinding_point = msg.blinding_point;
298 match next_blinding_point.mul_tweak(&self.secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) {
301 log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
307 onion_routing_packet: outgoing_packet,
310 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
311 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
312 log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
317 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
319 match pending_per_peer_msgs.entry(next_node_id) {
320 hash_map::Entry::Vacant(_) => {
321 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
324 hash_map::Entry::Occupied(mut e) => {
325 e.get_mut().push_back(onion_message);
326 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
331 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
334 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
339 fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init) {
340 if init.features.supports_onion_messages() {
341 let mut peers = self.pending_messages.lock().unwrap();
342 peers.insert(their_node_id.clone(), VecDeque::new());
346 fn peer_disconnected(&self, their_node_id: &PublicKey, _no_connection_possible: bool) {
347 let mut pending_msgs = self.pending_messages.lock().unwrap();
348 pending_msgs.remove(their_node_id);
351 fn provided_node_features(&self) -> NodeFeatures {
352 let mut features = NodeFeatures::empty();
353 features.set_onion_messages_optional();
357 fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
358 let mut features = InitFeatures::empty();
359 features.set_onion_messages_optional();
364 impl<Signer: Sign, K: Deref, L: Deref> OnionMessageProvider for OnionMessenger<Signer, K, L>
365 where K::Target: KeysInterface<Signer = Signer>,
368 fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
369 let mut pending_msgs = self.pending_messages.lock().unwrap();
370 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
371 return msgs.pop_front()
377 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
379 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
380 /// [`SimpleArcPeerManager`]. See their docs for more details.
382 /// (C-not exported) as `Arc`s don't make sense in bindings.
384 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
385 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
386 pub type SimpleArcOnionMessenger<L> = OnionMessenger<InMemorySigner, Arc<KeysManager>, Arc<L>>;
387 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
388 /// [`SimpleRefPeerManager`]. See their docs for more details.
390 /// (C-not exported) as general type aliases don't make sense in bindings.
392 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
393 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
394 pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<InMemorySigner, &'a KeysManager, &'b L>;
396 /// Construct onion packet payloads and keys for sending an onion message along the given
397 /// `unblinded_path` to the given `destination`.
398 fn packet_payloads_and_keys<T: secp256k1::Signing + secp256k1::Verification>(
399 secp_ctx: &Secp256k1<T>, unblinded_path: &[PublicKey], destination: Destination, mut reply_path:
400 Option<BlindedRoute>, session_priv: &SecretKey
401 ) -> Result<(Vec<(Payload, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
402 let num_hops = unblinded_path.len() + destination.num_hops();
403 let mut payloads = Vec::with_capacity(num_hops);
404 let mut onion_packet_keys = Vec::with_capacity(num_hops);
406 let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedRoute(BlindedRoute {
407 introduction_node_id, blinding_point, blinded_hops }) = &destination {
408 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
409 let num_unblinded_hops = num_hops - num_blinded_hops;
411 let mut unblinded_path_idx = 0;
412 let mut blinded_path_idx = 0;
413 let mut prev_control_tlvs_ss = None;
414 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| {
415 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
416 if let Some(ss) = prev_control_tlvs_ss.take() {
417 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
419 next_node_id: unblinded_pk_opt.unwrap(),
420 next_blinding_override: None,
424 prev_control_tlvs_ss = Some(control_tlvs_ss);
425 unblinded_path_idx += 1;
426 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
427 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
428 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
429 next_node_id: intro_node_id,
430 next_blinding_override: Some(blinding_pt),
431 })), control_tlvs_ss));
433 if let Some(encrypted_payload) = enc_payload_opt {
434 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(encrypted_payload)),
436 } else { debug_assert!(false); }
437 blinded_path_idx += 1;
438 } else if blinded_path_idx < num_blinded_hops - 1 && enc_payload_opt.is_some() {
439 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
441 blinded_path_idx += 1;
442 } else if let Some(encrypted_payload) = enc_payload_opt {
443 payloads.push((Payload::Receive {
444 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_payload),
445 reply_path: reply_path.take(),
446 }, control_tlvs_ss));
449 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
450 onion_packet_keys.push(onion_utils::OnionKeys {
452 shared_secret: onion_packet_ss,
454 blinding_factor: [0; 32],
461 if let Some(control_tlvs_ss) = prev_control_tlvs_ss {
462 payloads.push((Payload::Receive {
463 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
464 reply_path: reply_path.take(),
465 }, control_tlvs_ss));
468 Ok((payloads, onion_packet_keys))
471 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
472 fn construct_onion_message_packet(payloads: Vec<(Payload, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
474 // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
475 // onion, but this should be used sparingly as it is reduces anonymity set, hence the
476 // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
477 let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
478 let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
479 SMALL_PACKET_HOP_DATA_LEN
480 } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
481 BIG_PACKET_HOP_DATA_LEN
482 } else { return Err(()) };
484 Ok(onion_utils::construct_onion_message_packet::<_, _>(
485 payloads, onion_keys, prng_seed, hop_data_len))