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::{BlindedRoute, Destination, OnionMessenger};
45 /// # use lightning::util::logger::{Logger, Record};
46 /// # use std::sync::Arc;
47 /// # struct FakeLogger {};
48 /// # impl Logger for FakeLogger {
49 /// # fn log(&self, record: &Record) { unimplemented!() }
51 /// # let seed = [42u8; 32];
52 /// # let time = Duration::from_secs(123456);
53 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
54 /// # let logger = Arc::new(FakeLogger {});
55 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
56 /// # let secp_ctx = Secp256k1::new();
57 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
58 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1,
60 /// # let destination_node_id = hop_node_id1;
62 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
63 /// // ChannelManager.
64 /// let onion_messenger = OnionMessenger::new(&keys_manager, logger);
66 /// // Send an empty onion message to a node id.
67 /// let intermediate_hops = [hop_node_id1, hop_node_id2];
68 /// let reply_path = None;
69 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::Node(destination_node_id), reply_path);
71 /// // Create a blinded route to yourself, for someone to send an onion message to.
72 /// # let your_node_id = hop_node_id1;
73 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
74 /// let blinded_route = BlindedRoute::new(&hops, &keys_manager, &secp_ctx).unwrap();
76 /// // Send an empty onion message to a blinded route.
77 /// # let intermediate_hops = [hop_node_id1, hop_node_id2];
78 /// let reply_path = None;
79 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::BlindedRoute(blinded_route), reply_path);
82 /// [offers]: <https://github.com/lightning/bolts/pull/798>
83 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
84 pub struct OnionMessenger<Signer: Sign, K: Deref, L: Deref>
85 where K::Target: KeysInterface<Signer = Signer>,
90 pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
91 secp_ctx: Secp256k1<secp256k1::All>,
93 // invoice_handler: InvoiceHandler,
94 // custom_handler: CustomHandler, // handles custom onion messages
97 /// The destination of an onion message.
98 pub enum Destination {
99 /// We're sending this onion message to a node.
101 /// We're sending this onion message to a blinded route.
102 BlindedRoute(BlindedRoute),
106 pub(super) fn num_hops(&self) -> usize {
108 Destination::Node(_) => 1,
109 Destination::BlindedRoute(BlindedRoute { blinded_hops, .. }) => blinded_hops.len(),
114 /// Errors that may occur when [sending an onion message].
116 /// [sending an onion message]: OnionMessenger::send_onion_message
117 #[derive(Debug, PartialEq)]
119 /// Errored computing onion message packet keys.
120 Secp256k1(secp256k1::Error),
121 /// Because implementations such as Eclair will drop onion messages where the message packet
122 /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
124 /// The provided [`Destination`] was an invalid [`BlindedRoute`], due to having fewer than two
127 /// Our next-hop peer was offline or does not support onion message forwarding.
129 /// Our next-hop peer's buffer was full or our total outbound buffer was full.
133 impl<Signer: Sign, K: Deref, L: Deref> OnionMessenger<Signer, K, L>
134 where K::Target: KeysInterface<Signer = Signer>,
137 /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
138 /// their respective handlers.
139 pub fn new(keys_manager: K, logger: L) -> Self {
140 let mut secp_ctx = Secp256k1::new();
141 secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
144 pending_messages: Mutex::new(HashMap::new()),
150 /// Send an empty onion message to `destination`, routing it through `intermediate_nodes`.
151 /// See [`OnionMessenger`] for example usage.
152 pub fn send_onion_message(&self, intermediate_nodes: &[PublicKey], destination: Destination, reply_path: Option<BlindedRoute>) -> Result<(), SendError> {
153 if let Destination::BlindedRoute(BlindedRoute { ref blinded_hops, .. }) = destination {
154 if blinded_hops.len() < 2 {
155 return Err(SendError::TooFewBlindedHops);
158 let blinding_secret_bytes = self.keys_manager.get_secure_random_bytes();
159 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
160 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
161 (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
164 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
165 Destination::BlindedRoute(BlindedRoute { introduction_node_id, blinding_point, .. }) =>
166 (introduction_node_id, blinding_point),
169 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
170 &self.secp_ctx, intermediate_nodes, destination, reply_path, &blinding_secret)
171 .map_err(|e| SendError::Secp256k1(e))?;
173 let prng_seed = self.keys_manager.get_secure_random_bytes();
174 let onion_routing_packet = construct_onion_message_packet(
175 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
177 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
178 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
179 match pending_per_peer_msgs.entry(introduction_node_id) {
180 hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
181 hash_map::Entry::Occupied(mut e) => {
182 e.get_mut().push_back(msgs::OnionMessage { blinding_point, onion_routing_packet });
189 pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
190 let mut pending_msgs = self.pending_messages.lock().unwrap();
191 let mut msgs = HashMap::new();
192 // We don't want to disconnect the peers by removing them entirely from the original map, so we
193 // swap the pending message buffers individually.
194 for (peer_node_id, pending_messages) in &mut *pending_msgs {
195 msgs.insert(*peer_node_id, core::mem::take(pending_messages));
201 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
202 const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
203 const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
204 let mut total_buffered_bytes = 0;
205 let mut peer_buffered_bytes = 0;
206 for (pk, peer_buf) in buffer {
208 let om_len = om.serialized_length();
209 if pk == peer_node_id {
210 peer_buffered_bytes += om_len;
212 total_buffered_bytes += om_len;
214 if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
215 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
224 impl<Signer: Sign, K: Deref, L: Deref> OnionMessageHandler for OnionMessenger<Signer, K, L>
225 where K::Target: KeysInterface<Signer = Signer>,
228 /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
229 /// soon we'll delegate the onion message to a handler that can generate invoices or send
231 fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
232 let control_tlvs_ss = match self.keys_manager.ecdh(Recipient::Node, &msg.blinding_point, None) {
235 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
239 let onion_decode_ss = {
240 let blinding_factor = {
241 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
242 hmac.input(control_tlvs_ss.as_ref());
243 Hmac::from_engine(hmac).into_inner()
245 match self.keys_manager.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
246 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
248 Ok(ss) => ss.secret_bytes(),
250 log_trace!(self.logger, "Failed to compute onion packet shared secret");
255 match onion_utils::decode_next_hop(onion_decode_ss, &msg.onion_routing_packet.hop_data[..],
256 msg.onion_routing_packet.hmac, control_tlvs_ss)
258 Ok((Payload::Receive {
259 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
261 log_info!(self.logger,
262 "Received an onion message with path_id: {:02x?} and {}reply_path",
263 path_id, if reply_path.is_some() { "" } else { "no " });
265 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
266 next_node_id, next_blinding_override
267 })), Some((next_hop_hmac, new_packet_bytes)))) => {
268 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
269 // blinded hop and this onion message is destined for us. In this situation, we should keep
270 // unwrapping the onion layers to get to the final payload. Since we don't have the option
271 // of creating blinded routes with dummy hops currently, we should be ok to not handle this
273 let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
276 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
280 let outgoing_packet = Packet {
282 public_key: new_pubkey,
283 hop_data: new_packet_bytes,
286 let onion_message = msgs::OnionMessage {
287 blinding_point: match next_blinding_override {
288 Some(blinding_point) => blinding_point,
290 let blinding_factor = {
291 let mut sha = Sha256::engine();
292 sha.input(&msg.blinding_point.serialize()[..]);
293 sha.input(control_tlvs_ss.as_ref());
294 Sha256::from_engine(sha).into_inner()
296 let next_blinding_point = msg.blinding_point;
297 match next_blinding_point.mul_tweak(&self.secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) {
300 log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
306 onion_routing_packet: outgoing_packet,
309 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
310 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
311 log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
316 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
318 match pending_per_peer_msgs.entry(next_node_id) {
319 hash_map::Entry::Vacant(_) => {
320 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
323 hash_map::Entry::Occupied(mut e) => {
324 e.get_mut().push_back(onion_message);
325 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
330 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
333 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
338 fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init) -> Result<(), ()> {
339 if init.features.supports_onion_messages() {
340 let mut peers = self.pending_messages.lock().unwrap();
341 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))