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, 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 /// # let seed = [42u8; 32];
59 /// # let time = Duration::from_secs(123456);
60 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
61 /// # let logger = Arc::new(FakeLogger {});
62 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
63 /// # let secp_ctx = Secp256k1::new();
64 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
65 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
66 /// # let destination_node_id = hop_node_id1;
67 /// # let custom_message_handler = IgnoringMessageHandler {};
68 /// # let offers_message_handler = IgnoringMessageHandler {};
69 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
70 /// // ChannelManager.
71 /// let onion_messenger = OnionMessenger::new(&keys_manager, &keys_manager, logger, &offers_message_handler, &custom_message_handler);
73 /// # struct YourCustomMessage {}
74 /// impl Writeable for YourCustomMessage {
75 /// fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
77 /// // Write your custom onion message to `w`
80 /// impl CustomOnionMessageContents for YourCustomMessage {
81 /// fn tlv_type(&self) -> u64 {
82 /// # let your_custom_message_type = 42;
83 /// your_custom_message_type
86 /// // Send a custom onion message to a node id.
87 /// let path = OnionMessagePath {
88 /// intermediate_nodes: vec![hop_node_id1, hop_node_id2],
89 /// destination: Destination::Node(destination_node_id),
91 /// let reply_path = None;
92 /// # let your_custom_message = YourCustomMessage {};
93 /// let message = OnionMessageContents::Custom(your_custom_message);
94 /// onion_messenger.send_onion_message(path, message, reply_path);
96 /// // Create a blinded path to yourself, for someone to send an onion message to.
97 /// # let your_node_id = hop_node_id1;
98 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
99 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
101 /// // Send a custom onion message to a blinded path.
102 /// let path = OnionMessagePath {
103 /// intermediate_nodes: vec![hop_node_id1, hop_node_id2],
104 /// destination: Destination::BlindedPath(blinded_path),
106 /// let reply_path = None;
107 /// # let your_custom_message = YourCustomMessage {};
108 /// let message = OnionMessageContents::Custom(your_custom_message);
109 /// onion_messenger.send_onion_message(path, message, reply_path);
112 /// [offers]: <https://github.com/lightning/bolts/pull/798>
113 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
114 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, OMH: Deref, CMH: Deref>
116 ES::Target: EntropySource,
117 NS::Target: NodeSigner,
119 OMH::Target: OffersMessageHandler,
120 CMH:: Target: CustomOnionMessageHandler,
125 pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
126 secp_ctx: Secp256k1<secp256k1::All>,
131 /// A path for sending an [`msgs::OnionMessage`].
133 pub struct OnionMessagePath {
134 /// Nodes on the path between the sender and the destination.
135 pub intermediate_nodes: Vec<PublicKey>,
137 /// The recipient of the message.
138 pub destination: Destination,
141 /// The destination of an onion message.
143 pub enum Destination {
144 /// We're sending this onion message to a node.
146 /// We're sending this onion message to a blinded path.
147 BlindedPath(BlindedPath),
151 pub(super) fn num_hops(&self) -> usize {
153 Destination::Node(_) => 1,
154 Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
159 /// Errors that may occur when [sending an onion message].
161 /// [sending an onion message]: OnionMessenger::send_onion_message
162 #[derive(Debug, PartialEq, Eq)]
164 /// Errored computing onion message packet keys.
165 Secp256k1(secp256k1::Error),
166 /// Because implementations such as Eclair will drop onion messages where the message packet
167 /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
169 /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two
172 /// Our next-hop peer was offline or does not support onion message forwarding.
174 /// Onion message contents must have a TLV type >= 64.
176 /// Our next-hop peer's buffer was full or our total outbound buffer was full.
178 /// Failed to retrieve our node id from the provided [`NodeSigner`].
180 /// [`NodeSigner`]: crate::sign::NodeSigner
182 /// We attempted to send to a blinded path where we are the introduction node, and failed to
183 /// advance the blinded path to make the second hop the new introduction node. Either
184 /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
185 /// new blinding point, or we were attempting to send to ourselves.
186 BlindedPathAdvanceFailed,
189 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
190 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
191 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
192 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
195 /// See [`OnionMessenger`] for example usage.
197 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
198 /// [`CustomMessage`]: Self::CustomMessage
199 pub trait CustomOnionMessageHandler {
200 /// The message known to the handler. To support multiple message types, you may want to make this
201 /// an enum with a variant for each supported message.
202 type CustomMessage: CustomOnionMessageContents;
203 /// Called with the custom message that was received.
204 fn handle_custom_message(&self, msg: Self::CustomMessage);
205 /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
206 /// message type is unknown.
207 fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
210 impl<ES: Deref, NS: Deref, L: Deref, OMH: Deref, CMH: Deref> OnionMessenger<ES, NS, L, OMH, CMH>
212 ES::Target: EntropySource,
213 NS::Target: NodeSigner,
215 OMH::Target: OffersMessageHandler,
216 CMH::Target: CustomOnionMessageHandler,
218 /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
219 /// their respective handlers.
221 entropy_source: ES, node_signer: NS, logger: L, offers_handler: OMH, custom_handler: CMH
223 let mut secp_ctx = Secp256k1::new();
224 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
228 pending_messages: Mutex::new(HashMap::new()),
236 /// Send an onion message with contents `message` to the destination of `path`.
238 /// See [`OnionMessenger`] for example usage.
239 pub fn send_onion_message<T: CustomOnionMessageContents>(
240 &self, path: OnionMessagePath, message: OnionMessageContents<T>,
241 reply_path: Option<BlindedPath>
242 ) -> Result<(), SendError> {
243 let OnionMessagePath { intermediate_nodes, mut destination } = path;
244 if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
245 if blinded_hops.len() < 2 {
246 return Err(SendError::TooFewBlindedHops);
250 if message.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
252 // If we are sending straight to a blinded path and we are the introduction node, we need to
253 // advance the blinded path by 1 hop so the second hop is the new introduction node.
254 if intermediate_nodes.len() == 0 {
255 if let Destination::BlindedPath(ref mut blinded_path) = destination {
256 let our_node_id = self.node_signer.get_node_id(Recipient::Node)
257 .map_err(|()| SendError::GetNodeIdFailed)?;
258 if blinded_path.introduction_node_id == our_node_id {
259 blinded_path.advance_message_path_by_one(&self.node_signer, &self.secp_ctx)
260 .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
265 let blinding_secret_bytes = self.entropy_source.get_secure_random_bytes();
266 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
267 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
268 (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
271 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
272 Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
273 (introduction_node_id, blinding_point),
276 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
277 &self.secp_ctx, &intermediate_nodes, destination, message, reply_path, &blinding_secret)
278 .map_err(|e| SendError::Secp256k1(e))?;
280 let prng_seed = self.entropy_source.get_secure_random_bytes();
281 let onion_routing_packet = construct_onion_message_packet(
282 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
284 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
285 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
286 match pending_per_peer_msgs.entry(introduction_node_id) {
287 hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
288 hash_map::Entry::Occupied(mut e) => {
289 e.get_mut().push_back(msgs::OnionMessage { blinding_point, onion_routing_packet });
296 pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
297 let mut pending_msgs = self.pending_messages.lock().unwrap();
298 let mut msgs = HashMap::new();
299 // We don't want to disconnect the peers by removing them entirely from the original map, so we
300 // swap the pending message buffers individually.
301 for (peer_node_id, pending_messages) in &mut *pending_msgs {
302 msgs.insert(*peer_node_id, core::mem::take(pending_messages));
308 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
309 const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
310 const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
311 let mut total_buffered_bytes = 0;
312 let mut peer_buffered_bytes = 0;
313 for (pk, peer_buf) in buffer {
315 let om_len = om.serialized_length();
316 if pk == peer_node_id {
317 peer_buffered_bytes += om_len;
319 total_buffered_bytes += om_len;
321 if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
322 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
331 impl<ES: Deref, NS: Deref, L: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
332 for OnionMessenger<ES, NS, L, OMH, CMH>
334 ES::Target: EntropySource,
335 NS::Target: NodeSigner,
337 OMH::Target: OffersMessageHandler,
338 CMH::Target: CustomOnionMessageHandler + Sized,
340 /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
341 /// soon we'll delegate the onion message to a handler that can generate invoices or send
343 fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
344 let control_tlvs_ss = match self.node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
347 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
351 let onion_decode_ss = {
352 let blinding_factor = {
353 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
354 hmac.input(control_tlvs_ss.as_ref());
355 Hmac::from_engine(hmac).into_inner()
357 match self.node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
358 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
360 Ok(ss) => ss.secret_bytes(),
362 log_trace!(self.logger, "Failed to compute onion packet shared secret");
367 match onion_utils::decode_next_untagged_hop(
368 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
369 (control_tlvs_ss, &*self.custom_handler, &*self.logger)
371 Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
372 message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
374 log_info!(self.logger,
375 "Received an onion message with path_id {:02x?} and {} reply_path",
376 path_id, if reply_path.is_some() { "a" } else { "no" });
378 OnionMessageContents::Offers(msg) => self.offers_handler.handle_message(msg),
379 OnionMessageContents::Custom(msg) => self.custom_handler.handle_custom_message(msg),
382 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
383 next_node_id, next_blinding_override
384 })), Some((next_hop_hmac, new_packet_bytes)))) => {
385 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
386 // blinded hop and this onion message is destined for us. In this situation, we should keep
387 // unwrapping the onion layers to get to the final payload. Since we don't have the option
388 // of creating blinded paths with dummy hops currently, we should be ok to not handle this
390 let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
393 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
397 let outgoing_packet = Packet {
399 public_key: new_pubkey,
400 hop_data: new_packet_bytes,
403 let onion_message = msgs::OnionMessage {
404 blinding_point: match next_blinding_override {
405 Some(blinding_point) => blinding_point,
407 let blinding_factor = {
408 let mut sha = Sha256::engine();
409 sha.input(&msg.blinding_point.serialize()[..]);
410 sha.input(control_tlvs_ss.as_ref());
411 Sha256::from_engine(sha).into_inner()
413 let next_blinding_point = msg.blinding_point;
414 match next_blinding_point.mul_tweak(&self.secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) {
417 log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
423 onion_routing_packet: outgoing_packet,
426 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
427 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
428 log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
433 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
435 match pending_per_peer_msgs.entry(next_node_id) {
436 hash_map::Entry::Vacant(_) => {
437 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
440 hash_map::Entry::Occupied(mut e) => {
441 e.get_mut().push_back(onion_message);
442 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
447 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
450 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
455 fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
456 if init.features.supports_onion_messages() {
457 let mut peers = self.pending_messages.lock().unwrap();
458 peers.insert(their_node_id.clone(), VecDeque::new());
463 fn peer_disconnected(&self, their_node_id: &PublicKey) {
464 let mut pending_msgs = self.pending_messages.lock().unwrap();
465 pending_msgs.remove(their_node_id);
468 fn provided_node_features(&self) -> NodeFeatures {
469 let mut features = NodeFeatures::empty();
470 features.set_onion_messages_optional();
474 fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
475 let mut features = InitFeatures::empty();
476 features.set_onion_messages_optional();
481 impl<ES: Deref, NS: Deref, L: Deref, OMH: Deref, CMH: Deref> OnionMessageProvider
482 for OnionMessenger<ES, NS, L, OMH, CMH>
484 ES::Target: EntropySource,
485 NS::Target: NodeSigner,
487 OMH::Target: OffersMessageHandler,
488 CMH::Target: CustomOnionMessageHandler,
490 fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
491 let mut pending_msgs = self.pending_messages.lock().unwrap();
492 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
493 return msgs.pop_front()
499 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
501 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
502 /// [`SimpleArcPeerManager`]. See their docs for more details.
504 /// This is not exported to bindings users as `Arc`s don't make sense in bindings.
506 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
507 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
508 pub type SimpleArcOnionMessenger<L> = OnionMessenger<
512 IgnoringMessageHandler,
513 IgnoringMessageHandler
516 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
517 /// [`SimpleRefPeerManager`]. See their docs for more details.
519 /// This is not exported to bindings users as general type aliases don't make sense in bindings.
521 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
522 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
523 pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<
527 IgnoringMessageHandler,
528 IgnoringMessageHandler
531 /// Construct onion packet payloads and keys for sending an onion message along the given
532 /// `unblinded_path` to the given `destination`.
533 fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
534 secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
535 message: OnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
536 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
537 let num_hops = unblinded_path.len() + destination.num_hops();
538 let mut payloads = Vec::with_capacity(num_hops);
539 let mut onion_packet_keys = Vec::with_capacity(num_hops);
541 let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
542 introduction_node_id, blinding_point, blinded_hops }) = &destination {
543 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
544 let num_unblinded_hops = num_hops - num_blinded_hops;
546 let mut unblinded_path_idx = 0;
547 let mut blinded_path_idx = 0;
548 let mut prev_control_tlvs_ss = None;
549 let mut final_control_tlvs = None;
550 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| {
551 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
552 if let Some(ss) = prev_control_tlvs_ss.take() {
553 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
555 next_node_id: unblinded_pk_opt.unwrap(),
556 next_blinding_override: None,
560 prev_control_tlvs_ss = Some(control_tlvs_ss);
561 unblinded_path_idx += 1;
562 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
563 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
564 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
565 next_node_id: intro_node_id,
566 next_blinding_override: Some(blinding_pt),
567 })), control_tlvs_ss));
570 if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
571 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
573 blinded_path_idx += 1;
574 } else if let Some(encrypted_payload) = enc_payload_opt {
575 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
576 prev_control_tlvs_ss = Some(control_tlvs_ss);
579 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
580 onion_packet_keys.push(onion_utils::OnionKeys {
582 shared_secret: onion_packet_ss,
584 blinding_factor: [0; 32],
591 if let Some(control_tlvs) = final_control_tlvs {
592 payloads.push((Payload::Receive {
594 reply_path: reply_path.take(),
596 }, prev_control_tlvs_ss.unwrap()));
598 payloads.push((Payload::Receive {
599 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
600 reply_path: reply_path.take(),
602 }, prev_control_tlvs_ss.unwrap()));
605 Ok((payloads, onion_packet_keys))
608 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
609 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, ()> {
611 // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
612 // onion, but this should be used sparingly as it is reduces anonymity set, hence the
613 // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
614 let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
615 let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
616 SMALL_PACKET_HOP_DATA_LEN
617 } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
618 BIG_PACKET_HOP_DATA_LEN
619 } else { return Err(()) };
621 onion_utils::construct_onion_message_packet::<_, _>(
622 payloads, onion_keys, prng_seed, hop_data_len)