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 crate::blinded_path::{BlindedPath, ForwardTlvs, ReceiveTlvs, utils};
19 use crate::sign::{EntropySource, KeysManager, NodeSigner, Recipient};
20 use crate::events::OnionMessageProvider;
21 use crate::ln::features::{InitFeatures, NodeFeatures};
22 use crate::ln::msgs::{self, OnionMessageHandler};
23 use crate::ln::onion_utils;
24 use crate::ln::peer_handler::IgnoringMessageHandler;
25 pub use super::packet::{CustomOnionMessageContents, OnionMessageContents};
26 use super::offers::OffersMessageHandler;
27 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
28 use crate::util::logger::Logger;
29 use crate::util::ser::Writeable;
33 use crate::sync::{Arc, Mutex};
34 use crate::prelude::*;
36 /// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be
37 /// used to retrieve invoices and fulfill invoice requests from [offers]. Currently, only sending
38 /// and receiving custom onion messages is supported.
43 /// # extern crate bitcoin;
44 /// # use bitcoin::hashes::_export::_core::time::Duration;
45 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
46 /// # use lightning::blinded_path::BlindedPath;
47 /// # use lightning::sign::KeysManager;
48 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
49 /// # use lightning::onion_message::{CustomOnionMessageContents, Destination, MessageRouter, OnionMessageContents, OnionMessagePath, OnionMessenger};
50 /// # use lightning::util::logger::{Logger, Record};
51 /// # use lightning::util::ser::{Writeable, Writer};
52 /// # use lightning::io;
53 /// # use std::sync::Arc;
54 /// # struct FakeLogger;
55 /// # impl Logger for FakeLogger {
56 /// # fn log(&self, record: &Record) { unimplemented!() }
58 /// # struct FakeMessageRouter {}
59 /// # impl MessageRouter for FakeMessageRouter {
60 /// # fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
61 /// # unimplemented!()
64 /// # let seed = [42u8; 32];
65 /// # let time = Duration::from_secs(123456);
66 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
67 /// # let logger = Arc::new(FakeLogger {});
68 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
69 /// # let secp_ctx = Secp256k1::new();
70 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
71 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
72 /// # let destination_node_id = hop_node_id1;
73 /// # let message_router = Arc::new(FakeMessageRouter {});
74 /// # let custom_message_handler = IgnoringMessageHandler {};
75 /// # let offers_message_handler = IgnoringMessageHandler {};
76 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
77 /// // ChannelManager.
78 /// let onion_messenger = OnionMessenger::new(
79 /// &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
80 /// &custom_message_handler
83 /// # struct YourCustomMessage {}
84 /// impl Writeable for YourCustomMessage {
85 /// fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
87 /// // Write your custom onion message to `w`
90 /// impl CustomOnionMessageContents for YourCustomMessage {
91 /// fn tlv_type(&self) -> u64 {
92 /// # let your_custom_message_type = 42;
93 /// your_custom_message_type
96 /// // Send a custom onion message to a node id.
97 /// let path = OnionMessagePath {
98 /// intermediate_nodes: vec![hop_node_id1, hop_node_id2],
99 /// destination: Destination::Node(destination_node_id),
101 /// let reply_path = None;
102 /// # let your_custom_message = YourCustomMessage {};
103 /// let message = OnionMessageContents::Custom(your_custom_message);
104 /// onion_messenger.send_onion_message(path, message, reply_path);
106 /// // Create a blinded path to yourself, for someone to send an onion message to.
107 /// # let your_node_id = hop_node_id1;
108 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
109 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
111 /// // Send a custom onion message to a blinded path.
112 /// let path = OnionMessagePath {
113 /// intermediate_nodes: vec![hop_node_id1, hop_node_id2],
114 /// destination: Destination::BlindedPath(blinded_path),
116 /// let reply_path = None;
117 /// # let your_custom_message = YourCustomMessage {};
118 /// let message = OnionMessageContents::Custom(your_custom_message);
119 /// onion_messenger.send_onion_message(path, message, reply_path);
122 /// [offers]: <https://github.com/lightning/bolts/pull/798>
123 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
124 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
126 ES::Target: EntropySource,
127 NS::Target: NodeSigner,
129 MR::Target: MessageRouter,
130 OMH::Target: OffersMessageHandler,
131 CMH:: Target: CustomOnionMessageHandler,
136 pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
137 secp_ctx: Secp256k1<secp256k1::All>,
143 /// A trait defining behavior for routing an [`OnionMessage`].
145 /// [`OnionMessage`]: msgs::OnionMessage
146 pub trait MessageRouter {
147 /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
149 /// [`OnionMessage`]: msgs::OnionMessage
151 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
152 ) -> Result<OnionMessagePath, ()>;
155 /// A path for sending an [`msgs::OnionMessage`].
157 pub struct OnionMessagePath {
158 /// Nodes on the path between the sender and the destination.
159 pub intermediate_nodes: Vec<PublicKey>,
161 /// The recipient of the message.
162 pub destination: Destination,
165 /// The destination of an onion message.
167 pub enum Destination {
168 /// We're sending this onion message to a node.
170 /// We're sending this onion message to a blinded path.
171 BlindedPath(BlindedPath),
175 pub(super) fn num_hops(&self) -> usize {
177 Destination::Node(_) => 1,
178 Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
183 /// Errors that may occur when [sending an onion message].
185 /// [sending an onion message]: OnionMessenger::send_onion_message
186 #[derive(Debug, PartialEq, Eq)]
188 /// Errored computing onion message packet keys.
189 Secp256k1(secp256k1::Error),
190 /// Because implementations such as Eclair will drop onion messages where the message packet
191 /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
193 /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two
196 /// Our next-hop peer was offline or does not support onion message forwarding.
198 /// Onion message contents must have a TLV type >= 64.
200 /// Our next-hop peer's buffer was full or our total outbound buffer was full.
202 /// Failed to retrieve our node id from the provided [`NodeSigner`].
204 /// [`NodeSigner`]: crate::sign::NodeSigner
206 /// We attempted to send to a blinded path where we are the introduction node, and failed to
207 /// advance the blinded path to make the second hop the new introduction node. Either
208 /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
209 /// new blinding point, or we were attempting to send to ourselves.
210 BlindedPathAdvanceFailed,
213 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
214 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
215 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
216 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
219 /// See [`OnionMessenger`] for example usage.
221 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
222 /// [`CustomMessage`]: Self::CustomMessage
223 pub trait CustomOnionMessageHandler {
224 /// The message known to the handler. To support multiple message types, you may want to make this
225 /// an enum with a variant for each supported message.
226 type CustomMessage: CustomOnionMessageContents;
228 /// Called with the custom message that was received, returning a response to send, if any.
229 fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
231 /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
232 /// message type is unknown.
233 fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
236 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
237 OnionMessenger<ES, NS, L, MR, OMH, CMH>
239 ES::Target: EntropySource,
240 NS::Target: NodeSigner,
242 MR::Target: MessageRouter,
243 OMH::Target: OffersMessageHandler,
244 CMH::Target: CustomOnionMessageHandler,
246 /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
247 /// their respective handlers.
249 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
252 let mut secp_ctx = Secp256k1::new();
253 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
257 pending_messages: Mutex::new(HashMap::new()),
266 /// Send an onion message with contents `message` to the destination of `path`.
268 /// See [`OnionMessenger`] for example usage.
269 pub fn send_onion_message<T: CustomOnionMessageContents>(
270 &self, path: OnionMessagePath, message: OnionMessageContents<T>,
271 reply_path: Option<BlindedPath>
272 ) -> Result<(), SendError> {
273 let OnionMessagePath { intermediate_nodes, mut destination } = path;
274 if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
275 if blinded_hops.len() < 2 {
276 return Err(SendError::TooFewBlindedHops);
280 if message.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
282 // If we are sending straight to a blinded path and we are the introduction node, we need to
283 // advance the blinded path by 1 hop so the second hop is the new introduction node.
284 if intermediate_nodes.len() == 0 {
285 if let Destination::BlindedPath(ref mut blinded_path) = destination {
286 let our_node_id = self.node_signer.get_node_id(Recipient::Node)
287 .map_err(|()| SendError::GetNodeIdFailed)?;
288 if blinded_path.introduction_node_id == our_node_id {
289 blinded_path.advance_message_path_by_one(&self.node_signer, &self.secp_ctx)
290 .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
295 let blinding_secret_bytes = self.entropy_source.get_secure_random_bytes();
296 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
297 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
298 (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
301 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
302 Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
303 (introduction_node_id, blinding_point),
306 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
307 &self.secp_ctx, &intermediate_nodes, destination, message, reply_path, &blinding_secret)
308 .map_err(|e| SendError::Secp256k1(e))?;
310 let prng_seed = self.entropy_source.get_secure_random_bytes();
311 let onion_routing_packet = construct_onion_message_packet(
312 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
314 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
315 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
316 match pending_per_peer_msgs.entry(introduction_node_id) {
317 hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
318 hash_map::Entry::Occupied(mut e) => {
319 e.get_mut().push_back(msgs::OnionMessage { blinding_point, onion_routing_packet });
325 fn respond_with_onion_message<T: CustomOnionMessageContents>(
326 &self, response: OnionMessageContents<T>, path_id: Option<[u8; 32]>,
327 reply_path: Option<BlindedPath>
329 let sender = match self.node_signer.get_node_id(Recipient::Node) {
330 Ok(node_id) => node_id,
333 self.logger, "Unable to retrieve node id when responding to onion message with \
334 path_id {:02x?}", path_id
340 let peers = self.pending_messages.lock().unwrap().keys().copied().collect();
342 let destination = match reply_path {
343 Some(reply_path) => Destination::BlindedPath(reply_path),
346 self.logger, "Missing reply path when responding to onion message with path_id \
353 let path = match self.message_router.find_path(sender, peers, destination) {
357 self.logger, "Failed to find path when responding to onion message with \
358 path_id {:02x?}", path_id
364 log_trace!(self.logger, "Responding to onion message with path_id {:02x?}", path_id);
366 if let Err(e) = self.send_onion_message(path, response, None) {
368 self.logger, "Failed responding to onion message with path_id {:02x?}: {:?}",
376 pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
377 let mut pending_msgs = self.pending_messages.lock().unwrap();
378 let mut msgs = HashMap::new();
379 // We don't want to disconnect the peers by removing them entirely from the original map, so we
380 // swap the pending message buffers individually.
381 for (peer_node_id, pending_messages) in &mut *pending_msgs {
382 msgs.insert(*peer_node_id, core::mem::take(pending_messages));
388 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
389 const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
390 const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
391 let mut total_buffered_bytes = 0;
392 let mut peer_buffered_bytes = 0;
393 for (pk, peer_buf) in buffer {
395 let om_len = om.serialized_length();
396 if pk == peer_node_id {
397 peer_buffered_bytes += om_len;
399 total_buffered_bytes += om_len;
401 if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
402 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
411 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
412 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
414 ES::Target: EntropySource,
415 NS::Target: NodeSigner,
417 MR::Target: MessageRouter,
418 OMH::Target: OffersMessageHandler,
419 CMH::Target: CustomOnionMessageHandler,
421 /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
422 /// soon we'll delegate the onion message to a handler that can generate invoices or send
424 fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
425 let control_tlvs_ss = match self.node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
428 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
432 let onion_decode_ss = {
433 let blinding_factor = {
434 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
435 hmac.input(control_tlvs_ss.as_ref());
436 Hmac::from_engine(hmac).into_inner()
438 match self.node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
439 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
441 Ok(ss) => ss.secret_bytes(),
443 log_trace!(self.logger, "Failed to compute onion packet shared secret");
448 match onion_utils::decode_next_untagged_hop(
449 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
450 (control_tlvs_ss, &*self.custom_handler, &*self.logger)
452 Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
453 message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
455 log_trace!(self.logger,
456 "Received an onion message with path_id {:02x?} and {} reply_path",
457 path_id, if reply_path.is_some() { "a" } else { "no" });
459 let response = match message {
460 OnionMessageContents::Offers(msg) => {
461 self.offers_handler.handle_message(msg)
462 .map(|msg| OnionMessageContents::Offers(msg))
464 OnionMessageContents::Custom(msg) => {
465 self.custom_handler.handle_custom_message(msg)
466 .map(|msg| OnionMessageContents::Custom(msg))
470 if let Some(response) = response {
471 self.respond_with_onion_message(response, path_id, reply_path);
474 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
475 next_node_id, next_blinding_override
476 })), Some((next_hop_hmac, new_packet_bytes)))) => {
477 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
478 // blinded hop and this onion message is destined for us. In this situation, we should keep
479 // unwrapping the onion layers to get to the final payload. Since we don't have the option
480 // of creating blinded paths with dummy hops currently, we should be ok to not handle this
482 let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
485 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
489 let outgoing_packet = Packet {
491 public_key: new_pubkey,
492 hop_data: new_packet_bytes,
495 let onion_message = msgs::OnionMessage {
496 blinding_point: match next_blinding_override {
497 Some(blinding_point) => blinding_point,
499 let blinding_factor = {
500 let mut sha = Sha256::engine();
501 sha.input(&msg.blinding_point.serialize()[..]);
502 sha.input(control_tlvs_ss.as_ref());
503 Sha256::from_engine(sha).into_inner()
505 let next_blinding_point = msg.blinding_point;
506 match next_blinding_point.mul_tweak(&self.secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) {
509 log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
515 onion_routing_packet: outgoing_packet,
518 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
519 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
520 log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
525 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
527 match pending_per_peer_msgs.entry(next_node_id) {
528 hash_map::Entry::Vacant(_) => {
529 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
532 hash_map::Entry::Occupied(mut e) => {
533 e.get_mut().push_back(onion_message);
534 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
539 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
542 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
547 fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
548 if init.features.supports_onion_messages() {
549 let mut peers = self.pending_messages.lock().unwrap();
550 peers.insert(their_node_id.clone(), VecDeque::new());
555 fn peer_disconnected(&self, their_node_id: &PublicKey) {
556 let mut pending_msgs = self.pending_messages.lock().unwrap();
557 pending_msgs.remove(their_node_id);
560 fn provided_node_features(&self) -> NodeFeatures {
561 let mut features = NodeFeatures::empty();
562 features.set_onion_messages_optional();
566 fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
567 let mut features = InitFeatures::empty();
568 features.set_onion_messages_optional();
573 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageProvider
574 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
576 ES::Target: EntropySource,
577 NS::Target: NodeSigner,
579 MR::Target: MessageRouter,
580 OMH::Target: OffersMessageHandler,
581 CMH::Target: CustomOnionMessageHandler,
583 fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
584 let mut pending_msgs = self.pending_messages.lock().unwrap();
585 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
586 return msgs.pop_front()
592 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
594 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
595 /// [`SimpleArcPeerManager`]. See their docs for more details.
597 /// This is not exported to bindings users as `Arc`s don't make sense in bindings.
599 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
600 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
601 pub type SimpleArcOnionMessenger<L, R> = OnionMessenger<
606 IgnoringMessageHandler,
607 IgnoringMessageHandler
610 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
611 /// [`SimpleRefPeerManager`]. See their docs for more details.
613 /// This is not exported to bindings users as general type aliases don't make sense in bindings.
615 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
616 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
617 pub type SimpleRefOnionMessenger<'a, 'b, 'c, L, R> = OnionMessenger<
622 IgnoringMessageHandler,
623 IgnoringMessageHandler
626 /// Construct onion packet payloads and keys for sending an onion message along the given
627 /// `unblinded_path` to the given `destination`.
628 fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
629 secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
630 message: OnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
631 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
632 let num_hops = unblinded_path.len() + destination.num_hops();
633 let mut payloads = Vec::with_capacity(num_hops);
634 let mut onion_packet_keys = Vec::with_capacity(num_hops);
636 let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
637 introduction_node_id, blinding_point, blinded_hops }) = &destination {
638 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
639 let num_unblinded_hops = num_hops - num_blinded_hops;
641 let mut unblinded_path_idx = 0;
642 let mut blinded_path_idx = 0;
643 let mut prev_control_tlvs_ss = None;
644 let mut final_control_tlvs = None;
645 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| {
646 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
647 if let Some(ss) = prev_control_tlvs_ss.take() {
648 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
650 next_node_id: unblinded_pk_opt.unwrap(),
651 next_blinding_override: None,
655 prev_control_tlvs_ss = Some(control_tlvs_ss);
656 unblinded_path_idx += 1;
657 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
658 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
659 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
660 next_node_id: intro_node_id,
661 next_blinding_override: Some(blinding_pt),
662 })), control_tlvs_ss));
665 if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
666 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
668 blinded_path_idx += 1;
669 } else if let Some(encrypted_payload) = enc_payload_opt {
670 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
671 prev_control_tlvs_ss = Some(control_tlvs_ss);
674 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
675 onion_packet_keys.push(onion_utils::OnionKeys {
677 shared_secret: onion_packet_ss,
679 blinding_factor: [0; 32],
686 if let Some(control_tlvs) = final_control_tlvs {
687 payloads.push((Payload::Receive {
689 reply_path: reply_path.take(),
691 }, prev_control_tlvs_ss.unwrap()));
693 payloads.push((Payload::Receive {
694 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
695 reply_path: reply_path.take(),
697 }, prev_control_tlvs_ss.unwrap()));
700 Ok((payloads, onion_packet_keys))
703 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
704 fn construct_onion_message_packet<T: CustomOnionMessageContents>(payloads: Vec<(Payload<T>, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
706 // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
707 // onion, but this should be used sparingly as it is reduces anonymity set, hence the
708 // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
709 let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
710 let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
711 SMALL_PACKET_HOP_DATA_LEN
712 } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
713 BIG_PACKET_HOP_DATA_LEN
714 } else { return Err(()) };
716 onion_utils::construct_onion_message_packet::<_, _>(
717 payloads, onion_keys, prng_seed, hop_data_len)