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::msgs::{self, OnionMessageHandler};
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};
24 use util::events::OnionMessageProvider;
25 use util::logger::Logger;
26 use util::ser::Writeable;
29 use sync::{Arc, Mutex};
32 /// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be
33 /// used to retrieve invoices and fulfill invoice requests from [offers]. Currently, only sending
34 /// and receiving empty onion messages is supported.
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!() }
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,
59 /// # let destination_node_id = hop_node_id1;
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);
65 /// // Send an empty onion message to a node id.
66 /// let intermediate_hops = [hop_node_id1, hop_node_id2];
67 /// let reply_path = None;
68 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::Node(destination_node_id), reply_path);
70 /// // Create a blinded route to yourself, for someone to send an onion message to.
71 /// # let your_node_id = hop_node_id1;
72 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
73 /// let blinded_route = BlindedRoute::new::<InMemorySigner, _, _>(&hops, &keys_manager, &secp_ctx).unwrap();
75 /// // Send an empty onion message to a blinded route.
76 /// # let intermediate_hops = [hop_node_id1, hop_node_id2];
77 /// let reply_path = None;
78 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::BlindedRoute(blinded_route), reply_path);
81 /// [offers]: <https://github.com/lightning/bolts/pull/798>
82 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
83 pub struct OnionMessenger<Signer: Sign, K: Deref, L: Deref>
84 where K::Target: KeysInterface<Signer = Signer>,
89 pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
90 secp_ctx: Secp256k1<secp256k1::All>,
92 // invoice_handler: InvoiceHandler,
93 // custom_handler: CustomHandler, // handles custom onion messages
96 /// The destination of an onion message.
97 pub enum Destination {
98 /// We're sending this onion message to a node.
100 /// We're sending this onion message to a blinded route.
101 BlindedRoute(BlindedRoute),
105 pub(super) fn num_hops(&self) -> usize {
107 Destination::Node(_) => 1,
108 Destination::BlindedRoute(BlindedRoute { blinded_hops, .. }) => blinded_hops.len(),
113 /// Errors that may occur when [sending an onion message].
115 /// [sending an onion message]: OnionMessenger::send_onion_message
116 #[derive(Debug, PartialEq)]
118 /// Errored computing onion message packet keys.
119 Secp256k1(secp256k1::Error),
120 /// Because implementations such as Eclair will drop onion messages where the message packet
121 /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
123 /// The provided [`Destination`] was an invalid [`BlindedRoute`], due to having fewer than two
126 /// Our next-hop peer was offline or does not support onion message forwarding.
128 /// Our next-hop peer's buffer was full or our total outbound buffer was full.
132 impl<Signer: Sign, K: Deref, L: Deref> OnionMessenger<Signer, K, L>
133 where K::Target: KeysInterface<Signer = Signer>,
136 /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
137 /// their respective handlers.
138 pub fn new(keys_manager: K, logger: L) -> Self {
139 let mut secp_ctx = Secp256k1::new();
140 secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
143 pending_messages: Mutex::new(HashMap::new()),
149 /// Send an empty onion message to `destination`, routing it through `intermediate_nodes`.
150 /// See [`OnionMessenger`] for example usage.
151 pub fn send_onion_message(&self, intermediate_nodes: &[PublicKey], destination: Destination, reply_path: Option<BlindedRoute>) -> Result<(), SendError> {
152 if let Destination::BlindedRoute(BlindedRoute { ref blinded_hops, .. }) = destination {
153 if blinded_hops.len() < 2 {
154 return Err(SendError::TooFewBlindedHops);
157 let blinding_secret_bytes = self.keys_manager.get_secure_random_bytes();
158 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
159 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
160 (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
163 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
164 Destination::BlindedRoute(BlindedRoute { introduction_node_id, blinding_point, .. }) =>
165 (introduction_node_id, blinding_point),
168 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
169 &self.secp_ctx, intermediate_nodes, destination, reply_path, &blinding_secret)
170 .map_err(|e| SendError::Secp256k1(e))?;
172 let prng_seed = self.keys_manager.get_secure_random_bytes();
173 let onion_routing_packet = construct_onion_message_packet(
174 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
176 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
177 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
178 match pending_per_peer_msgs.entry(introduction_node_id) {
179 hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
180 hash_map::Entry::Occupied(mut e) => {
181 e.get_mut().push_back(msgs::OnionMessage { blinding_point, onion_routing_packet });
188 pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
189 let mut pending_msgs = self.pending_messages.lock().unwrap();
190 let mut msgs = HashMap::new();
191 // We don't want to disconnect the peers by removing them entirely from the original map, so we
192 // swap the pending message buffers individually.
193 for (peer_node_id, pending_messages) in &mut *pending_msgs {
194 msgs.insert(*peer_node_id, core::mem::take(pending_messages));
200 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
201 const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
202 const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
203 let mut total_buffered_bytes = 0;
204 let mut peer_buffered_bytes = 0;
205 for (pk, peer_buf) in buffer {
207 let om_len = om.serialized_length();
208 if pk == peer_node_id {
209 peer_buffered_bytes += om_len;
211 total_buffered_bytes += om_len;
213 if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
214 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
223 impl<Signer: Sign, K: Deref, L: Deref> OnionMessageHandler for OnionMessenger<Signer, K, L>
224 where K::Target: KeysInterface<Signer = Signer>,
227 /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
228 /// soon we'll delegate the onion message to a handler that can generate invoices or send
230 fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
231 let control_tlvs_ss = match self.keys_manager.ecdh(Recipient::Node, &msg.blinding_point, None) {
234 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
238 let onion_decode_ss = {
239 let blinding_factor = {
240 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
241 hmac.input(control_tlvs_ss.as_ref());
242 Hmac::from_engine(hmac).into_inner()
244 match self.keys_manager.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
245 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
247 Ok(ss) => ss.secret_bytes(),
249 log_trace!(self.logger, "Failed to compute onion packet shared secret");
254 match onion_utils::decode_next_hop(onion_decode_ss, &msg.onion_routing_packet.hop_data[..],
255 msg.onion_routing_packet.hmac, control_tlvs_ss)
257 Ok((Payload::Receive {
258 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
260 log_info!(self.logger,
261 "Received an onion message with path_id: {:02x?} and {}reply_path",
262 path_id, if reply_path.is_some() { "" } else { "no " });
264 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
265 next_node_id, next_blinding_override
266 })), Some((next_hop_hmac, new_packet_bytes)))) => {
267 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
268 // blinded hop and this onion message is destined for us. In this situation, we should keep
269 // unwrapping the onion layers to get to the final payload. Since we don't have the option
270 // of creating blinded routes with dummy hops currently, we should be ok to not handle this
272 let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
275 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
279 let outgoing_packet = Packet {
281 public_key: new_pubkey,
282 hop_data: new_packet_bytes,
285 let onion_message = msgs::OnionMessage {
286 blinding_point: match next_blinding_override {
287 Some(blinding_point) => blinding_point,
289 let blinding_factor = {
290 let mut sha = Sha256::engine();
291 sha.input(&msg.blinding_point.serialize()[..]);
292 sha.input(control_tlvs_ss.as_ref());
293 Sha256::from_engine(sha).into_inner()
295 let next_blinding_point = msg.blinding_point;
296 match next_blinding_point.mul_tweak(&self.secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) {
299 log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
305 onion_routing_packet: outgoing_packet,
308 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
309 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
310 log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
315 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
317 match pending_per_peer_msgs.entry(next_node_id) {
318 hash_map::Entry::Vacant(_) => {
319 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
322 hash_map::Entry::Occupied(mut e) => {
323 e.get_mut().push_back(onion_message);
324 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
329 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
332 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
337 fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init) {
338 if init.features.supports_onion_messages() {
339 let mut peers = self.pending_messages.lock().unwrap();
340 peers.insert(their_node_id.clone(), VecDeque::new());
344 fn peer_disconnected(&self, their_node_id: &PublicKey, _no_connection_possible: bool) {
345 let mut pending_msgs = self.pending_messages.lock().unwrap();
346 pending_msgs.remove(their_node_id);
350 impl<Signer: Sign, K: Deref, L: Deref> OnionMessageProvider for OnionMessenger<Signer, K, L>
351 where K::Target: KeysInterface<Signer = Signer>,
354 fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
355 let mut pending_msgs = self.pending_messages.lock().unwrap();
356 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
357 return msgs.pop_front()
363 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
365 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
366 /// [`SimpleArcPeerManager`]. See their docs for more details.
368 ///[`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
369 ///[`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
370 pub type SimpleArcOnionMessenger<L> = OnionMessenger<InMemorySigner, Arc<KeysManager>, Arc<L>>;
371 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
372 /// [`SimpleRefPeerManager`]. See their docs for more details.
374 ///[`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
375 ///[`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
376 pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<InMemorySigner, &'a KeysManager, &'b L>;
378 /// Construct onion packet payloads and keys for sending an onion message along the given
379 /// `unblinded_path` to the given `destination`.
380 fn packet_payloads_and_keys<T: secp256k1::Signing + secp256k1::Verification>(
381 secp_ctx: &Secp256k1<T>, unblinded_path: &[PublicKey], destination: Destination, mut reply_path:
382 Option<BlindedRoute>, session_priv: &SecretKey
383 ) -> Result<(Vec<(Payload, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
384 let num_hops = unblinded_path.len() + destination.num_hops();
385 let mut payloads = Vec::with_capacity(num_hops);
386 let mut onion_packet_keys = Vec::with_capacity(num_hops);
388 let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedRoute(BlindedRoute {
389 introduction_node_id, blinding_point, blinded_hops }) = &destination {
390 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
391 let num_unblinded_hops = num_hops - num_blinded_hops;
393 let mut unblinded_path_idx = 0;
394 let mut blinded_path_idx = 0;
395 let mut prev_control_tlvs_ss = None;
396 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| {
397 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
398 if let Some(ss) = prev_control_tlvs_ss.take() {
399 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
401 next_node_id: unblinded_pk_opt.unwrap(),
402 next_blinding_override: None,
406 prev_control_tlvs_ss = Some(control_tlvs_ss);
407 unblinded_path_idx += 1;
408 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
409 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
410 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
411 next_node_id: intro_node_id,
412 next_blinding_override: Some(blinding_pt),
413 })), control_tlvs_ss));
415 if let Some(encrypted_payload) = enc_payload_opt {
416 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(encrypted_payload)),
418 } else { debug_assert!(false); }
419 blinded_path_idx += 1;
420 } else if blinded_path_idx < num_blinded_hops - 1 && enc_payload_opt.is_some() {
421 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
423 blinded_path_idx += 1;
424 } else if let Some(encrypted_payload) = enc_payload_opt {
425 payloads.push((Payload::Receive {
426 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_payload),
427 reply_path: reply_path.take(),
428 }, control_tlvs_ss));
431 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
432 onion_packet_keys.push(onion_utils::OnionKeys {
434 shared_secret: onion_packet_ss,
436 blinding_factor: [0; 32],
443 if let Some(control_tlvs_ss) = prev_control_tlvs_ss {
444 payloads.push((Payload::Receive {
445 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
446 reply_path: reply_path.take(),
447 }, control_tlvs_ss));
450 Ok((payloads, onion_packet_keys))
453 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
454 fn construct_onion_message_packet(payloads: Vec<(Payload, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
456 // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
457 // onion, but this should be used sparingly as it is reduces anonymity set, hence the
458 // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
459 let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
460 let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
461 SMALL_PACKET_HOP_DATA_LEN
462 } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
463 BIG_PACKET_HOP_DATA_LEN
464 } else { return Err(()) };
466 Ok(onion_utils::construct_onion_message_packet::<_, _>(
467 payloads, onion_keys, prng_seed, hop_data_len))