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;
28 use sync::{Arc, Mutex};
31 /// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be
32 /// used to retrieve invoices and fulfill invoice requests from [offers]. Currently, only sending
33 /// and receiving empty onion messages is supported.
38 /// # extern crate bitcoin;
39 /// # use bitcoin::hashes::_export::_core::time::Duration;
40 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
41 /// # use lightning::chain::keysinterface::{InMemorySigner, KeysManager, KeysInterface};
42 /// # use lightning::onion_message::{BlindedRoute, Destination, OnionMessenger};
43 /// # use lightning::util::logger::{Logger, Record};
44 /// # use std::sync::Arc;
45 /// # struct FakeLogger {};
46 /// # impl Logger for FakeLogger {
47 /// # fn log(&self, record: &Record) { unimplemented!() }
49 /// # let seed = [42u8; 32];
50 /// # let time = Duration::from_secs(123456);
51 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
52 /// # let logger = Arc::new(FakeLogger {});
53 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
54 /// # let secp_ctx = Secp256k1::new();
55 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
56 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1,
58 /// # let destination_node_id = hop_node_id1;
60 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
61 /// // ChannelManager.
62 /// let onion_messenger = OnionMessenger::new(&keys_manager, logger);
64 /// // Send an empty onion message to a node id.
65 /// let intermediate_hops = [hop_node_id1, hop_node_id2];
66 /// let reply_path = None;
67 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::Node(destination_node_id), reply_path);
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();
74 /// // Send an empty onion message to a blinded route.
75 /// # let intermediate_hops = [hop_node_id1, hop_node_id2];
76 /// let reply_path = None;
77 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::BlindedRoute(blinded_route), reply_path);
80 /// [offers]: <https://github.com/lightning/bolts/pull/798>
81 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
82 pub struct OnionMessenger<Signer: Sign, K: Deref, L: Deref>
83 where K::Target: KeysInterface<Signer = Signer>,
88 pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
89 secp_ctx: Secp256k1<secp256k1::All>,
91 // invoice_handler: InvoiceHandler,
92 // custom_handler: CustomHandler, // handles custom onion messages
95 /// The destination of an onion message.
96 pub enum Destination {
97 /// We're sending this onion message to a node.
99 /// We're sending this onion message to a blinded route.
100 BlindedRoute(BlindedRoute),
104 pub(super) fn num_hops(&self) -> usize {
106 Destination::Node(_) => 1,
107 Destination::BlindedRoute(BlindedRoute { blinded_hops, .. }) => blinded_hops.len(),
112 /// Errors that may occur when [sending an onion message].
114 /// [sending an onion message]: OnionMessenger::send_onion_message
115 #[derive(Debug, PartialEq)]
117 /// Errored computing onion message packet keys.
118 Secp256k1(secp256k1::Error),
119 /// Because implementations such as Eclair will drop onion messages where the message packet
120 /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
122 /// The provided [`Destination`] was an invalid [`BlindedRoute`], due to having fewer than two
127 impl<Signer: Sign, K: Deref, L: Deref> OnionMessenger<Signer, K, L>
128 where K::Target: KeysInterface<Signer = Signer>,
131 /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
132 /// their respective handlers.
133 pub fn new(keys_manager: K, logger: L) -> Self {
134 let mut secp_ctx = Secp256k1::new();
135 secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
138 pending_messages: Mutex::new(HashMap::new()),
144 /// Send an empty onion message to `destination`, routing it through `intermediate_nodes`.
145 /// See [`OnionMessenger`] for example usage.
146 pub fn send_onion_message(&self, intermediate_nodes: &[PublicKey], destination: Destination, reply_path: Option<BlindedRoute>) -> Result<(), SendError> {
147 if let Destination::BlindedRoute(BlindedRoute { ref blinded_hops, .. }) = destination {
148 if blinded_hops.len() < 2 {
149 return Err(SendError::TooFewBlindedHops);
152 let blinding_secret_bytes = self.keys_manager.get_secure_random_bytes();
153 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
154 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
155 (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
158 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
159 Destination::BlindedRoute(BlindedRoute { introduction_node_id, blinding_point, .. }) =>
160 (introduction_node_id, blinding_point),
163 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
164 &self.secp_ctx, intermediate_nodes, destination, reply_path, &blinding_secret)
165 .map_err(|e| SendError::Secp256k1(e))?;
167 let prng_seed = self.keys_manager.get_secure_random_bytes();
168 let onion_packet = construct_onion_message_packet(
169 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
171 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
172 let pending_msgs = pending_per_peer_msgs.entry(introduction_node_id).or_insert_with(VecDeque::new);
173 pending_msgs.push_back(
176 onion_routing_packet: onion_packet,
183 pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
184 let mut pending_msgs = self.pending_messages.lock().unwrap();
185 let mut msgs = HashMap::new();
186 core::mem::swap(&mut *pending_msgs, &mut msgs);
191 impl<Signer: Sign, K: Deref, L: Deref> OnionMessageHandler for OnionMessenger<Signer, K, L>
192 where K::Target: KeysInterface<Signer = Signer>,
195 /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
196 /// soon we'll delegate the onion message to a handler that can generate invoices or send
198 fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
199 let control_tlvs_ss = match self.keys_manager.ecdh(Recipient::Node, &msg.blinding_point, None) {
202 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
206 let onion_decode_ss = {
207 let blinding_factor = {
208 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
209 hmac.input(control_tlvs_ss.as_ref());
210 Hmac::from_engine(hmac).into_inner()
212 match self.keys_manager.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
213 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
215 Ok(ss) => ss.secret_bytes(),
217 log_trace!(self.logger, "Failed to compute onion packet shared secret");
222 match onion_utils::decode_next_hop(onion_decode_ss, &msg.onion_routing_packet.hop_data[..],
223 msg.onion_routing_packet.hmac, control_tlvs_ss)
225 Ok((Payload::Receive {
226 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
228 log_info!(self.logger,
229 "Received an onion message with path_id: {:02x?} and {}reply_path",
230 path_id, if reply_path.is_some() { "" } else { "no " });
232 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
233 next_node_id, next_blinding_override
234 })), Some((next_hop_hmac, new_packet_bytes)))) => {
235 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
236 // blinded hop and this onion message is destined for us. In this situation, we should keep
237 // unwrapping the onion layers to get to the final payload. Since we don't have the option
238 // of creating blinded routes with dummy hops currently, we should be ok to not handle this
240 let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
243 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
247 let outgoing_packet = Packet {
249 public_key: new_pubkey,
250 hop_data: new_packet_bytes,
254 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
255 let pending_msgs = pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
256 pending_msgs.push_back(
258 blinding_point: match next_blinding_override {
259 Some(blinding_point) => blinding_point,
261 let blinding_factor = {
262 let mut sha = Sha256::engine();
263 sha.input(&msg.blinding_point.serialize()[..]);
264 sha.input(control_tlvs_ss.as_ref());
265 Sha256::from_engine(sha).into_inner()
267 let next_blinding_point = msg.blinding_point;
268 match next_blinding_point.mul_tweak(&self.secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) {
271 log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
277 onion_routing_packet: outgoing_packet,
280 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
283 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
286 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
292 impl<Signer: Sign, K: Deref, L: Deref> OnionMessageProvider for OnionMessenger<Signer, K, L>
293 where K::Target: KeysInterface<Signer = Signer>,
296 fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
297 let mut pending_msgs = self.pending_messages.lock().unwrap();
298 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
299 return msgs.pop_front()
305 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
307 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
308 /// [`SimpleArcPeerManager`]. See their docs for more details.
310 ///[`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
311 ///[`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
312 pub type SimpleArcOnionMessenger<L> = OnionMessenger<InMemorySigner, Arc<KeysManager>, Arc<L>>;
313 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
314 /// [`SimpleRefPeerManager`]. See their docs for more details.
316 ///[`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
317 ///[`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
318 pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<InMemorySigner, &'a KeysManager, &'b L>;
320 /// Construct onion packet payloads and keys for sending an onion message along the given
321 /// `unblinded_path` to the given `destination`.
322 fn packet_payloads_and_keys<T: secp256k1::Signing + secp256k1::Verification>(
323 secp_ctx: &Secp256k1<T>, unblinded_path: &[PublicKey], destination: Destination, mut reply_path:
324 Option<BlindedRoute>, session_priv: &SecretKey
325 ) -> Result<(Vec<(Payload, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
326 let num_hops = unblinded_path.len() + destination.num_hops();
327 let mut payloads = Vec::with_capacity(num_hops);
328 let mut onion_packet_keys = Vec::with_capacity(num_hops);
330 let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedRoute(BlindedRoute {
331 introduction_node_id, blinding_point, blinded_hops }) = &destination {
332 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
333 let num_unblinded_hops = num_hops - num_blinded_hops;
335 let mut unblinded_path_idx = 0;
336 let mut blinded_path_idx = 0;
337 let mut prev_control_tlvs_ss = None;
338 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| {
339 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
340 if let Some(ss) = prev_control_tlvs_ss.take() {
341 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
343 next_node_id: unblinded_pk_opt.unwrap(),
344 next_blinding_override: None,
348 prev_control_tlvs_ss = Some(control_tlvs_ss);
349 unblinded_path_idx += 1;
350 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
351 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
352 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
353 next_node_id: intro_node_id,
354 next_blinding_override: Some(blinding_pt),
355 })), control_tlvs_ss));
357 if let Some(encrypted_payload) = enc_payload_opt {
358 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(encrypted_payload)),
360 } else { debug_assert!(false); }
361 blinded_path_idx += 1;
362 } else if blinded_path_idx < num_blinded_hops - 1 && enc_payload_opt.is_some() {
363 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
365 blinded_path_idx += 1;
366 } else if let Some(encrypted_payload) = enc_payload_opt {
367 payloads.push((Payload::Receive {
368 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_payload),
369 reply_path: reply_path.take(),
370 }, control_tlvs_ss));
373 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
374 onion_packet_keys.push(onion_utils::OnionKeys {
376 shared_secret: onion_packet_ss,
378 blinding_factor: [0; 32],
385 if let Some(control_tlvs_ss) = prev_control_tlvs_ss {
386 payloads.push((Payload::Receive {
387 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
388 reply_path: reply_path.take(),
389 }, control_tlvs_ss));
392 Ok((payloads, onion_packet_keys))
395 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
396 fn construct_onion_message_packet(payloads: Vec<(Payload, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
398 // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
399 // onion, but this should be used sparingly as it is reduces anonymity set, hence the
400 // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
401 let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
402 let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
403 SMALL_PACKET_HOP_DATA_LEN
404 } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
405 BIG_PACKET_HOP_DATA_LEN
406 } else { return Err(()) };
408 Ok(onion_utils::construct_onion_message_packet::<_, _>(
409 payloads, onion_keys, prng_seed, hop_data_len))