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 ln::peer_handler::IgnoringMessageHandler;
23 use super::blinded_route::{BlindedRoute, ForwardTlvs, ReceiveTlvs};
24 pub use super::packet::CustomOnionMessageContents;
25 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
27 use util::events::OnionMessageProvider;
28 use util::logger::Logger;
29 use util::ser::Writeable;
32 use sync::{Arc, Mutex};
35 /// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be
36 /// used to retrieve invoices and fulfill invoice requests from [offers]. Currently, only sending
37 /// and receiving empty onion messages is supported.
42 /// # extern crate bitcoin;
43 /// # use bitcoin::hashes::_export::_core::time::Duration;
44 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
45 /// # use lightning::chain::keysinterface::{InMemorySigner, KeysManager, KeysInterface};
46 /// # use lightning::ln::msgs::DecodeError;
47 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
48 /// # use lightning::onion_message::{BlindedRoute, CustomOnionMessageContents, Destination, OnionMessenger};
49 /// # use lightning::util::logger::{Logger, Record};
50 /// # use lightning::util::ser::{MaybeReadableArgs, Writeable, Writer};
51 /// # use lightning::io;
52 /// # use std::sync::Arc;
53 /// # struct FakeLogger {};
54 /// # impl Logger for FakeLogger {
55 /// # fn log(&self, record: &Record) { unimplemented!() }
57 /// # let seed = [42u8; 32];
58 /// # let time = Duration::from_secs(123456);
59 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
60 /// # let logger = Arc::new(FakeLogger {});
61 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
62 /// # let secp_ctx = Secp256k1::new();
63 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
64 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
65 /// # let destination_node_id = hop_node_id1;
66 /// # let your_custom_message_handler = IgnoringMessageHandler {};
67 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
68 /// // ChannelManager.
69 /// let onion_messenger = OnionMessenger::new(&keys_manager, logger, your_custom_message_handler);
71 /// # struct YourCustomMessage {}
72 /// impl Writeable for YourCustomMessage {
73 /// fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
75 /// // Write your custom onion message to `w`
78 /// impl CustomOnionMessageContents for YourCustomMessage {
79 /// fn tlv_type(&self) -> u64 {
80 /// # let your_custom_message_type = 42;
81 /// your_custom_message_type
84 /// impl MaybeReadableArgs<u64> for YourCustomMessage {
85 /// fn read<R: io::Read>(r: &mut R, message_type: u64) -> Result<Option<Self>, DecodeError> {
87 /// // Read your custom onion message of type `message_type` from `r`, or return `None`
88 /// // if the message type is unknown
91 /// let intermediate_hops = [hop_node_id1, hop_node_id2];
92 /// let reply_path = None;
93 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::Node(destination_node_id), reply_path);
95 /// // Create a blinded route to yourself, for someone to send an onion message to.
96 /// # let your_node_id = hop_node_id1;
97 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
98 /// let blinded_route = BlindedRoute::new(&hops, &keys_manager, &secp_ctx).unwrap();
100 /// // Send an empty onion message to a blinded route.
101 /// # let intermediate_hops = [hop_node_id1, hop_node_id2];
102 /// let reply_path = None;
103 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::BlindedRoute(blinded_route), reply_path);
106 /// [offers]: <https://github.com/lightning/bolts/pull/798>
107 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
108 pub struct OnionMessenger<Signer: Sign, K: Deref, L: Deref, CMH: Deref>
109 where K::Target: KeysInterface<Signer = Signer>,
111 CMH:: Target: CustomOnionMessageHandler,
115 pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
116 secp_ctx: Secp256k1<secp256k1::All>,
119 // invoice_handler: InvoiceHandler,
122 /// The destination of an onion message.
123 pub enum Destination {
124 /// We're sending this onion message to a node.
126 /// We're sending this onion message to a blinded route.
127 BlindedRoute(BlindedRoute),
131 pub(super) fn num_hops(&self) -> usize {
133 Destination::Node(_) => 1,
134 Destination::BlindedRoute(BlindedRoute { blinded_hops, .. }) => blinded_hops.len(),
139 /// Errors that may occur when [sending an onion message].
141 /// [sending an onion message]: OnionMessenger::send_onion_message
142 #[derive(Debug, PartialEq)]
144 /// Errored computing onion message packet keys.
145 Secp256k1(secp256k1::Error),
146 /// Because implementations such as Eclair will drop onion messages where the message packet
147 /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
149 /// The provided [`Destination`] was an invalid [`BlindedRoute`], due to having fewer than two
152 /// Our next-hop peer was offline or does not support onion message forwarding.
154 /// Our next-hop peer's buffer was full or our total outbound buffer was full.
158 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
159 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
160 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
161 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
164 /// See [`OnionMessenger`] for example usage.
166 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
167 /// [`CustomMessage`]: Self::CustomMessage
168 pub trait CustomOnionMessageHandler {
169 /// The message known to the handler. To support multiple message types, you may want to make this
170 /// an enum with a variant for each supported message.
171 type CustomMessage: CustomOnionMessageContents;
172 /// Called with the custom message that was received.
173 fn handle_custom_message(&self, msg: Self::CustomMessage);
176 impl<Signer: Sign, K: Deref, L: Deref, CMH: Deref> OnionMessenger<Signer, K, L, CMH>
177 where K::Target: KeysInterface<Signer = Signer>,
179 CMH::Target: CustomOnionMessageHandler,
181 /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
182 /// their respective handlers.
183 pub fn new(keys_manager: K, logger: L, custom_handler: CMH) -> Self {
184 let mut secp_ctx = Secp256k1::new();
185 secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
188 pending_messages: Mutex::new(HashMap::new()),
195 /// Send an empty onion message to `destination`, routing it through `intermediate_nodes`.
196 /// See [`OnionMessenger`] for example usage.
197 pub fn send_onion_message(&self, intermediate_nodes: &[PublicKey], destination: Destination, reply_path: Option<BlindedRoute>) -> Result<(), SendError> {
198 if let Destination::BlindedRoute(BlindedRoute { ref blinded_hops, .. }) = destination {
199 if blinded_hops.len() < 2 {
200 return Err(SendError::TooFewBlindedHops);
203 let blinding_secret_bytes = self.keys_manager.get_secure_random_bytes();
204 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
205 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
206 (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
209 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
210 Destination::BlindedRoute(BlindedRoute { introduction_node_id, blinding_point, .. }) =>
211 (introduction_node_id, blinding_point),
214 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
215 &self.secp_ctx, intermediate_nodes, destination, reply_path, &blinding_secret)
216 .map_err(|e| SendError::Secp256k1(e))?;
218 let prng_seed = self.keys_manager.get_secure_random_bytes();
219 let onion_routing_packet = construct_onion_message_packet(
220 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
222 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
223 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
224 match pending_per_peer_msgs.entry(introduction_node_id) {
225 hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
226 hash_map::Entry::Occupied(mut e) => {
227 e.get_mut().push_back(msgs::OnionMessage { blinding_point, onion_routing_packet });
234 pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
235 let mut pending_msgs = self.pending_messages.lock().unwrap();
236 let mut msgs = HashMap::new();
237 // We don't want to disconnect the peers by removing them entirely from the original map, so we
238 // swap the pending message buffers individually.
239 for (peer_node_id, pending_messages) in &mut *pending_msgs {
240 msgs.insert(*peer_node_id, core::mem::take(pending_messages));
246 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
247 const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
248 const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
249 let mut total_buffered_bytes = 0;
250 let mut peer_buffered_bytes = 0;
251 for (pk, peer_buf) in buffer {
253 let om_len = om.serialized_length();
254 if pk == peer_node_id {
255 peer_buffered_bytes += om_len;
257 total_buffered_bytes += om_len;
259 if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
260 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
269 impl<Signer: Sign, K: Deref, L: Deref, CMH: Deref> OnionMessageHandler for OnionMessenger<Signer, K, L, CMH>
270 where K::Target: KeysInterface<Signer = Signer>,
272 CMH::Target: CustomOnionMessageHandler,
274 /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
275 /// soon we'll delegate the onion message to a handler that can generate invoices or send
277 fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
278 let control_tlvs_ss = match self.keys_manager.ecdh(Recipient::Node, &msg.blinding_point, None) {
281 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
285 let onion_decode_ss = {
286 let blinding_factor = {
287 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
288 hmac.input(control_tlvs_ss.as_ref());
289 Hmac::from_engine(hmac).into_inner()
291 match self.keys_manager.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
292 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
294 Ok(ss) => ss.secret_bytes(),
296 log_trace!(self.logger, "Failed to compute onion packet shared secret");
301 match onion_utils::decode_next_hop(onion_decode_ss, &msg.onion_routing_packet.hop_data[..],
302 msg.onion_routing_packet.hmac, control_tlvs_ss)
304 Ok((Payload::Receive {
305 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
307 log_info!(self.logger,
308 "Received an onion message with path_id {:02x?} and {} reply_path",
309 path_id, if reply_path.is_some() { "a" } else { "no" });
311 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
312 next_node_id, next_blinding_override
313 })), Some((next_hop_hmac, new_packet_bytes)))) => {
314 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
315 // blinded hop and this onion message is destined for us. In this situation, we should keep
316 // unwrapping the onion layers to get to the final payload. Since we don't have the option
317 // of creating blinded routes with dummy hops currently, we should be ok to not handle this
319 let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
322 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
326 let outgoing_packet = Packet {
328 public_key: new_pubkey,
329 hop_data: new_packet_bytes,
332 let onion_message = msgs::OnionMessage {
333 blinding_point: match next_blinding_override {
334 Some(blinding_point) => blinding_point,
336 let blinding_factor = {
337 let mut sha = Sha256::engine();
338 sha.input(&msg.blinding_point.serialize()[..]);
339 sha.input(control_tlvs_ss.as_ref());
340 Sha256::from_engine(sha).into_inner()
342 let next_blinding_point = msg.blinding_point;
343 match next_blinding_point.mul_tweak(&self.secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) {
346 log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
352 onion_routing_packet: outgoing_packet,
355 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
356 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
357 log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
362 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
364 match pending_per_peer_msgs.entry(next_node_id) {
365 hash_map::Entry::Vacant(_) => {
366 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
369 hash_map::Entry::Occupied(mut e) => {
370 e.get_mut().push_back(onion_message);
371 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
376 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
379 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
384 fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init) -> Result<(), ()> {
385 if init.features.supports_onion_messages() {
386 let mut peers = self.pending_messages.lock().unwrap();
387 peers.insert(their_node_id.clone(), VecDeque::new());
392 fn peer_disconnected(&self, their_node_id: &PublicKey, _no_connection_possible: bool) {
393 let mut pending_msgs = self.pending_messages.lock().unwrap();
394 pending_msgs.remove(their_node_id);
397 fn provided_node_features(&self) -> NodeFeatures {
398 let mut features = NodeFeatures::empty();
399 features.set_onion_messages_optional();
403 fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
404 let mut features = InitFeatures::empty();
405 features.set_onion_messages_optional();
410 impl<Signer: Sign, K: Deref, L: Deref, CMH: Deref> OnionMessageProvider for OnionMessenger<Signer, K, L, CMH>
411 where K::Target: KeysInterface<Signer = Signer>,
413 CMH::Target: CustomOnionMessageHandler,
415 fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
416 let mut pending_msgs = self.pending_messages.lock().unwrap();
417 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
418 return msgs.pop_front()
424 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
426 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
427 /// [`SimpleArcPeerManager`]. See their docs for more details.
429 /// (C-not exported) as `Arc`s don't make sense in bindings.
431 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
432 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
433 pub type SimpleArcOnionMessenger<L> = OnionMessenger<InMemorySigner, Arc<KeysManager>, Arc<L>, IgnoringMessageHandler>;
434 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
435 /// [`SimpleRefPeerManager`]. See their docs for more details.
437 /// (C-not exported) as general type aliases don't make sense in bindings.
439 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
440 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
441 pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<InMemorySigner, &'a KeysManager, &'b L, IgnoringMessageHandler>;
443 /// Construct onion packet payloads and keys for sending an onion message along the given
444 /// `unblinded_path` to the given `destination`.
445 fn packet_payloads_and_keys<T: secp256k1::Signing + secp256k1::Verification>(
446 secp_ctx: &Secp256k1<T>, unblinded_path: &[PublicKey], destination: Destination, mut reply_path:
447 Option<BlindedRoute>, session_priv: &SecretKey
448 ) -> Result<(Vec<(Payload, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
449 let num_hops = unblinded_path.len() + destination.num_hops();
450 let mut payloads = Vec::with_capacity(num_hops);
451 let mut onion_packet_keys = Vec::with_capacity(num_hops);
453 let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedRoute(BlindedRoute {
454 introduction_node_id, blinding_point, blinded_hops }) = &destination {
455 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
456 let num_unblinded_hops = num_hops - num_blinded_hops;
458 let mut unblinded_path_idx = 0;
459 let mut blinded_path_idx = 0;
460 let mut prev_control_tlvs_ss = None;
461 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| {
462 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
463 if let Some(ss) = prev_control_tlvs_ss.take() {
464 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
466 next_node_id: unblinded_pk_opt.unwrap(),
467 next_blinding_override: None,
471 prev_control_tlvs_ss = Some(control_tlvs_ss);
472 unblinded_path_idx += 1;
473 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
474 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
475 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
476 next_node_id: intro_node_id,
477 next_blinding_override: Some(blinding_pt),
478 })), control_tlvs_ss));
480 if let Some(encrypted_payload) = enc_payload_opt {
481 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(encrypted_payload)),
483 } else { debug_assert!(false); }
484 blinded_path_idx += 1;
485 } else if blinded_path_idx < num_blinded_hops - 1 && enc_payload_opt.is_some() {
486 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
488 blinded_path_idx += 1;
489 } else if let Some(encrypted_payload) = enc_payload_opt {
490 payloads.push((Payload::Receive {
491 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_payload),
492 reply_path: reply_path.take(),
493 }, control_tlvs_ss));
496 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
497 onion_packet_keys.push(onion_utils::OnionKeys {
499 shared_secret: onion_packet_ss,
501 blinding_factor: [0; 32],
508 if let Some(control_tlvs_ss) = prev_control_tlvs_ss {
509 payloads.push((Payload::Receive {
510 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
511 reply_path: reply_path.take(),
512 }, control_tlvs_ss));
515 Ok((payloads, onion_packet_keys))
518 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
519 fn construct_onion_message_packet(payloads: Vec<(Payload, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
521 // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
522 // onion, but this should be used sparingly as it is reduces anonymity set, hence the
523 // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
524 let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
525 let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
526 SMALL_PACKET_HOP_DATA_LEN
527 } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
528 BIG_PACKET_HOP_DATA_LEN
529 } else { return Err(()) };
531 Ok(onion_utils::construct_onion_message_packet::<_, _>(
532 payloads, onion_keys, prng_seed, hop_data_len))