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, Secp256k1, SecretKey};
18 use chain::keysinterface::{InMemorySigner, KeysInterface, KeysManager, Recipient, Sign};
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::logger::Logger;
27 use sync::{Arc, Mutex};
30 /// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be
31 /// used to retrieve invoices and fulfill invoice requests from [offers].
33 /// [offers]: <https://github.com/lightning/bolts/pull/798>
34 pub struct OnionMessenger<Signer: Sign, K: Deref, L: Deref>
35 where K::Target: KeysInterface<Signer = Signer>,
40 pending_messages: Mutex<HashMap<PublicKey, Vec<msgs::OnionMessage>>>,
41 secp_ctx: Secp256k1<secp256k1::All>,
43 // invoice_handler: InvoiceHandler,
44 // custom_handler: CustomHandler, // handles custom onion messages
47 /// The destination of an onion message.
48 pub enum Destination {
49 /// We're sending this onion message to a node.
51 /// We're sending this onion message to a blinded route.
52 BlindedRoute(BlindedRoute),
56 pub(super) fn num_hops(&self) -> usize {
58 Destination::Node(_) => 1,
59 Destination::BlindedRoute(BlindedRoute { blinded_hops, .. }) => blinded_hops.len(),
64 impl<Signer: Sign, K: Deref, L: Deref> OnionMessenger<Signer, K, L>
65 where K::Target: KeysInterface<Signer = Signer>,
68 /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
69 /// their respective handlers.
70 pub fn new(keys_manager: K, logger: L) -> Self {
71 let mut secp_ctx = Secp256k1::new();
72 secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
75 pending_messages: Mutex::new(HashMap::new()),
81 /// Send an empty onion message to `destination`, routing it through `intermediate_nodes`.
82 pub fn send_onion_message(&self, intermediate_nodes: &[PublicKey], destination: Destination) -> Result<(), secp256k1::Error> {
83 let blinding_secret_bytes = self.keys_manager.get_secure_random_bytes();
84 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
85 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
86 (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
89 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
90 Destination::BlindedRoute(BlindedRoute { introduction_node_id, blinding_point, .. }) =>
91 (introduction_node_id, blinding_point),
94 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
95 &self.secp_ctx, intermediate_nodes, destination, &blinding_secret)?;
97 let prng_seed = self.keys_manager.get_secure_random_bytes();
98 let onion_packet = construct_onion_message_packet(packet_payloads, packet_keys, prng_seed);
100 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
101 let pending_msgs = pending_per_peer_msgs.entry(introduction_node_id).or_insert(Vec::new());
105 onion_routing_packet: onion_packet,
111 /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
112 /// soon we'll delegate the onion message to a handler that can generate invoices or send
114 pub fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
115 let control_tlvs_ss = match self.keys_manager.ecdh(Recipient::Node, &msg.blinding_point, None) {
118 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
122 let onion_decode_ss = {
123 let blinding_factor = {
124 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
125 hmac.input(control_tlvs_ss.as_ref());
126 Hmac::from_engine(hmac).into_inner()
128 match self.keys_manager.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
129 Some(&blinding_factor))
131 Ok(ss) => ss.secret_bytes(),
133 log_trace!(self.logger, "Failed to compute onion packet shared secret");
138 match onion_utils::decode_next_hop(onion_decode_ss, &msg.onion_routing_packet.hop_data[..],
139 msg.onion_routing_packet.hmac, control_tlvs_ss)
141 Ok((Payload::Receive {
142 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id })
144 log_info!(self.logger, "Received an onion message with path_id: {:02x?}", path_id);
146 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
147 next_node_id, next_blinding_override
148 })), Some((next_hop_hmac, new_packet_bytes)))) => {
149 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
150 // blinded hop and this onion message is destined for us. In this situation, we should keep
151 // unwrapping the onion layers to get to the final payload. Since we don't have the option
152 // of creating blinded routes with dummy hops currently, we should be ok to not handle this
154 let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
157 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
161 let outgoing_packet = Packet {
163 public_key: new_pubkey,
164 hop_data: new_packet_bytes,
168 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
169 let pending_msgs = pending_per_peer_msgs.entry(next_node_id).or_insert(Vec::new());
172 blinding_point: match next_blinding_override {
173 Some(blinding_point) => blinding_point,
175 let blinding_factor = {
176 let mut sha = Sha256::engine();
177 sha.input(&msg.blinding_point.serialize()[..]);
178 sha.input(control_tlvs_ss.as_ref());
179 Sha256::from_engine(sha).into_inner()
181 let mut next_blinding_point = msg.blinding_point;
182 if let Err(e) = next_blinding_point.mul_assign(&self.secp_ctx, &blinding_factor[..]) {
183 log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
189 onion_routing_packet: outgoing_packet,
194 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
197 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
203 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
205 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
206 /// [`SimpleArcPeerManager`]. See their docs for more details.
208 ///[`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
209 ///[`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
210 pub type SimpleArcOnionMessenger<L> = OnionMessenger<InMemorySigner, Arc<KeysManager>, Arc<L>>;
211 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
212 /// [`SimpleRefPeerManager`]. See their docs for more details.
214 ///[`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
215 ///[`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
216 pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<InMemorySigner, &'a KeysManager, &'b L>;
218 /// Construct onion packet payloads and keys for sending an onion message along the given
219 /// `unblinded_path` to the given `destination`.
220 fn packet_payloads_and_keys<T: secp256k1::Signing + secp256k1::Verification>(
221 secp_ctx: &Secp256k1<T>, unblinded_path: &[PublicKey], destination: Destination, session_priv: &SecretKey
222 ) -> Result<(Vec<(Payload, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
223 let num_hops = unblinded_path.len() + destination.num_hops();
224 let mut payloads = Vec::with_capacity(num_hops);
225 let mut onion_packet_keys = Vec::with_capacity(num_hops);
227 let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedRoute(BlindedRoute {
228 introduction_node_id, blinding_point, blinded_hops }) = &destination {
229 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
230 let num_unblinded_hops = num_hops - num_blinded_hops;
232 let mut unblinded_path_idx = 0;
233 let mut blinded_path_idx = 0;
234 let mut prev_control_tlvs_ss = None;
235 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| {
236 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
237 if let Some(ss) = prev_control_tlvs_ss.take() {
238 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
240 next_node_id: unblinded_pk_opt.unwrap(),
241 next_blinding_override: None,
245 prev_control_tlvs_ss = Some(control_tlvs_ss);
246 unblinded_path_idx += 1;
247 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
248 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
249 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
250 next_node_id: intro_node_id,
251 next_blinding_override: Some(blinding_pt),
252 })), control_tlvs_ss));
254 if let Some(encrypted_payload) = enc_payload_opt {
255 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(encrypted_payload)),
257 } else { debug_assert!(false); }
258 blinded_path_idx += 1;
259 } else if blinded_path_idx < num_blinded_hops - 1 && enc_payload_opt.is_some() {
260 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
262 blinded_path_idx += 1;
263 } else if let Some(encrypted_payload) = enc_payload_opt {
264 payloads.push((Payload::Receive {
265 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_payload),
266 }, control_tlvs_ss));
269 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
270 onion_packet_keys.push(onion_utils::OnionKeys {
272 shared_secret: onion_packet_ss,
274 blinding_factor: [0; 32],
281 if let Some(control_tlvs_ss) = prev_control_tlvs_ss {
282 payloads.push((Payload::Receive {
283 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, })
284 }, control_tlvs_ss));
287 Ok((payloads, onion_packet_keys))
290 fn construct_onion_message_packet(payloads: Vec<(Payload, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Packet {
292 // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
293 // onion, but this should be used sparingly as it is reduces anonymity set, hence the
294 // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
295 let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
296 let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
297 SMALL_PACKET_HOP_DATA_LEN
298 } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
299 BIG_PACKET_HOP_DATA_LEN
300 } else { payloads_ser_len };
302 onion_utils::construct_onion_message_packet::<_, _>(payloads, onion_keys, prng_seed, hop_data_len)