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::chain::keysinterface::{InMemorySigner, KeysInterface, KeysManager, Recipient, Sign};
19 use crate::ln::features::{InitFeatures, NodeFeatures};
20 use crate::ln::msgs::{self, OnionMessageHandler};
21 use crate::ln::onion_utils;
22 use crate::ln::peer_handler::IgnoringMessageHandler;
23 use super::blinded_route::{BlindedRoute, ForwardTlvs, ReceiveTlvs};
24 pub use super::packet::{CustomOnionMessageContents, OnionMessageContents};
25 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
27 use crate::util::events::OnionMessageProvider;
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::chain::keysinterface::{InMemorySigner, KeysManager, KeysInterface};
47 /// # use lightning::ln::msgs::DecodeError;
48 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
49 /// # use lightning::onion_message::{BlindedRoute, CustomOnionMessageContents, Destination, OnionMessageContents, 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 your_custom_message_handler = IgnoringMessageHandler {};
68 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
69 /// // ChannelManager.
70 /// let onion_messenger = OnionMessenger::new(&keys_manager, logger, your_custom_message_handler);
72 /// # struct YourCustomMessage {}
73 /// impl Writeable for YourCustomMessage {
74 /// fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
76 /// // Write your custom onion message to `w`
79 /// impl CustomOnionMessageContents for YourCustomMessage {
80 /// fn tlv_type(&self) -> u64 {
81 /// # let your_custom_message_type = 42;
82 /// your_custom_message_type
85 /// // Send a custom onion message to a node id.
86 /// let intermediate_hops = [hop_node_id1, hop_node_id2];
87 /// let reply_path = None;
88 /// # let your_custom_message = YourCustomMessage {};
89 /// let message = OnionMessageContents::Custom(your_custom_message);
90 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::Node(destination_node_id), message, reply_path);
92 /// // Create a blinded route to yourself, for someone to send an onion message to.
93 /// # let your_node_id = hop_node_id1;
94 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
95 /// let blinded_route = BlindedRoute::new(&hops, &keys_manager, &secp_ctx).unwrap();
97 /// // Send a custom onion message to a blinded route.
98 /// # let intermediate_hops = [hop_node_id1, hop_node_id2];
99 /// let reply_path = None;
100 /// # let your_custom_message = YourCustomMessage {};
101 /// let message = OnionMessageContents::Custom(your_custom_message);
102 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::BlindedRoute(blinded_route), message, reply_path);
105 /// [offers]: <https://github.com/lightning/bolts/pull/798>
106 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
107 pub struct OnionMessenger<Signer: Sign, K: Deref, L: Deref, CMH: Deref>
108 where K::Target: KeysInterface<Signer = Signer>,
110 CMH:: Target: CustomOnionMessageHandler,
114 pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
115 secp_ctx: Secp256k1<secp256k1::All>,
118 // invoice_handler: InvoiceHandler,
121 /// The destination of an onion message.
122 pub enum Destination {
123 /// We're sending this onion message to a node.
125 /// We're sending this onion message to a blinded route.
126 BlindedRoute(BlindedRoute),
130 pub(super) fn num_hops(&self) -> usize {
132 Destination::Node(_) => 1,
133 Destination::BlindedRoute(BlindedRoute { blinded_hops, .. }) => blinded_hops.len(),
138 /// Errors that may occur when [sending an onion message].
140 /// [sending an onion message]: OnionMessenger::send_onion_message
141 #[derive(Debug, PartialEq, Eq)]
143 /// Errored computing onion message packet keys.
144 Secp256k1(secp256k1::Error),
145 /// Because implementations such as Eclair will drop onion messages where the message packet
146 /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
148 /// The provided [`Destination`] was an invalid [`BlindedRoute`], due to having fewer than two
151 /// Our next-hop peer was offline or does not support onion message forwarding.
153 /// Onion message contents must have a TLV type >= 64.
155 /// Our next-hop peer's buffer was full or our total outbound buffer was full.
159 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
160 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
161 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
162 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
165 /// See [`OnionMessenger`] for example usage.
167 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
168 /// [`CustomMessage`]: Self::CustomMessage
169 pub trait CustomOnionMessageHandler {
170 /// The message known to the handler. To support multiple message types, you may want to make this
171 /// an enum with a variant for each supported message.
172 type CustomMessage: CustomOnionMessageContents;
173 /// Called with the custom message that was received.
174 fn handle_custom_message(&self, msg: Self::CustomMessage);
175 /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
176 /// message type is unknown.
177 fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
180 impl<Signer: Sign, K: Deref, L: Deref, CMH: Deref> OnionMessenger<Signer, K, L, CMH>
181 where K::Target: KeysInterface<Signer = Signer>,
183 CMH::Target: CustomOnionMessageHandler,
185 /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
186 /// their respective handlers.
187 pub fn new(keys_manager: K, logger: L, custom_handler: CMH) -> Self {
188 let mut secp_ctx = Secp256k1::new();
189 secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
192 pending_messages: Mutex::new(HashMap::new()),
199 /// Send an onion message with contents `message` to `destination`, routing it through `intermediate_nodes`.
200 /// See [`OnionMessenger`] for example usage.
201 pub fn send_onion_message<T: CustomOnionMessageContents>(&self, intermediate_nodes: &[PublicKey], destination: Destination, message: OnionMessageContents<T>, reply_path: Option<BlindedRoute>) -> Result<(), SendError> {
202 if let Destination::BlindedRoute(BlindedRoute { ref blinded_hops, .. }) = destination {
203 if blinded_hops.len() < 2 {
204 return Err(SendError::TooFewBlindedHops);
207 let OnionMessageContents::Custom(ref msg) = message;
208 if msg.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
210 let blinding_secret_bytes = self.keys_manager.get_secure_random_bytes();
211 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
212 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
213 (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
216 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
217 Destination::BlindedRoute(BlindedRoute { introduction_node_id, blinding_point, .. }) =>
218 (introduction_node_id, blinding_point),
221 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
222 &self.secp_ctx, intermediate_nodes, destination, message, reply_path, &blinding_secret)
223 .map_err(|e| SendError::Secp256k1(e))?;
225 let prng_seed = self.keys_manager.get_secure_random_bytes();
226 let onion_routing_packet = construct_onion_message_packet(
227 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
229 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
230 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
231 match pending_per_peer_msgs.entry(introduction_node_id) {
232 hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
233 hash_map::Entry::Occupied(mut e) => {
234 e.get_mut().push_back(msgs::OnionMessage { blinding_point, onion_routing_packet });
241 pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
242 let mut pending_msgs = self.pending_messages.lock().unwrap();
243 let mut msgs = HashMap::new();
244 // We don't want to disconnect the peers by removing them entirely from the original map, so we
245 // swap the pending message buffers individually.
246 for (peer_node_id, pending_messages) in &mut *pending_msgs {
247 msgs.insert(*peer_node_id, core::mem::take(pending_messages));
253 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
254 const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
255 const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
256 let mut total_buffered_bytes = 0;
257 let mut peer_buffered_bytes = 0;
258 for (pk, peer_buf) in buffer {
260 let om_len = om.serialized_length();
261 if pk == peer_node_id {
262 peer_buffered_bytes += om_len;
264 total_buffered_bytes += om_len;
266 if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
267 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
276 impl<Signer: Sign, K: Deref, L: Deref, CMH: Deref> OnionMessageHandler for OnionMessenger<Signer, K, L, CMH>
277 where K::Target: KeysInterface<Signer = Signer>,
279 CMH::Target: CustomOnionMessageHandler + Sized,
281 /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
282 /// soon we'll delegate the onion message to a handler that can generate invoices or send
284 fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
285 let control_tlvs_ss = match self.keys_manager.ecdh(Recipient::Node, &msg.blinding_point, None) {
288 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
292 let onion_decode_ss = {
293 let blinding_factor = {
294 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
295 hmac.input(control_tlvs_ss.as_ref());
296 Hmac::from_engine(hmac).into_inner()
298 match self.keys_manager.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
299 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
301 Ok(ss) => ss.secret_bytes(),
303 log_trace!(self.logger, "Failed to compute onion packet shared secret");
308 match onion_utils::decode_next_untagged_hop(onion_decode_ss, &msg.onion_routing_packet.hop_data[..],
309 msg.onion_routing_packet.hmac, (control_tlvs_ss, &*self.custom_handler))
311 Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
312 message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
314 log_info!(self.logger,
315 "Received an onion message with path_id {:02x?} and {} reply_path",
316 path_id, if reply_path.is_some() { "a" } else { "no" });
318 OnionMessageContents::Custom(msg) => self.custom_handler.handle_custom_message(msg),
321 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
322 next_node_id, next_blinding_override
323 })), Some((next_hop_hmac, new_packet_bytes)))) => {
324 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
325 // blinded hop and this onion message is destined for us. In this situation, we should keep
326 // unwrapping the onion layers to get to the final payload. Since we don't have the option
327 // of creating blinded routes with dummy hops currently, we should be ok to not handle this
329 let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
332 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
336 let outgoing_packet = Packet {
338 public_key: new_pubkey,
339 hop_data: new_packet_bytes,
342 let onion_message = msgs::OnionMessage {
343 blinding_point: match next_blinding_override {
344 Some(blinding_point) => blinding_point,
346 let blinding_factor = {
347 let mut sha = Sha256::engine();
348 sha.input(&msg.blinding_point.serialize()[..]);
349 sha.input(control_tlvs_ss.as_ref());
350 Sha256::from_engine(sha).into_inner()
352 let next_blinding_point = msg.blinding_point;
353 match next_blinding_point.mul_tweak(&self.secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) {
356 log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
362 onion_routing_packet: outgoing_packet,
365 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
366 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
367 log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
372 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
374 match pending_per_peer_msgs.entry(next_node_id) {
375 hash_map::Entry::Vacant(_) => {
376 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
379 hash_map::Entry::Occupied(mut e) => {
380 e.get_mut().push_back(onion_message);
381 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
386 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
389 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
394 fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init) -> Result<(), ()> {
395 if init.features.supports_onion_messages() {
396 let mut peers = self.pending_messages.lock().unwrap();
397 peers.insert(their_node_id.clone(), VecDeque::new());
402 fn peer_disconnected(&self, their_node_id: &PublicKey, _no_connection_possible: bool) {
403 let mut pending_msgs = self.pending_messages.lock().unwrap();
404 pending_msgs.remove(their_node_id);
407 fn provided_node_features(&self) -> NodeFeatures {
408 let mut features = NodeFeatures::empty();
409 features.set_onion_messages_optional();
413 fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
414 let mut features = InitFeatures::empty();
415 features.set_onion_messages_optional();
420 impl<Signer: Sign, K: Deref, L: Deref, CMH: Deref> OnionMessageProvider for OnionMessenger<Signer, K, L, CMH>
421 where K::Target: KeysInterface<Signer = Signer>,
423 CMH::Target: CustomOnionMessageHandler,
425 fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
426 let mut pending_msgs = self.pending_messages.lock().unwrap();
427 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
428 return msgs.pop_front()
434 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
436 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
437 /// [`SimpleArcPeerManager`]. See their docs for more details.
439 /// (C-not exported) as `Arc`s don't make sense in bindings.
441 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
442 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
443 pub type SimpleArcOnionMessenger<L> = OnionMessenger<InMemorySigner, Arc<KeysManager>, Arc<L>, IgnoringMessageHandler>;
444 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
445 /// [`SimpleRefPeerManager`]. See their docs for more details.
447 /// (C-not exported) as general type aliases don't make sense in bindings.
449 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
450 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
451 pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<InMemorySigner, &'a KeysManager, &'b L, IgnoringMessageHandler>;
453 /// Construct onion packet payloads and keys for sending an onion message along the given
454 /// `unblinded_path` to the given `destination`.
455 fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
456 secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
457 message: OnionMessageContents<T>, mut reply_path: Option<BlindedRoute>, session_priv: &SecretKey
458 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
459 let num_hops = unblinded_path.len() + destination.num_hops();
460 let mut payloads = Vec::with_capacity(num_hops);
461 let mut onion_packet_keys = Vec::with_capacity(num_hops);
463 let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedRoute(BlindedRoute {
464 introduction_node_id, blinding_point, blinded_hops }) = &destination {
465 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
466 let num_unblinded_hops = num_hops - num_blinded_hops;
468 let mut unblinded_path_idx = 0;
469 let mut blinded_path_idx = 0;
470 let mut prev_control_tlvs_ss = None;
471 let mut final_control_tlvs = None;
472 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| {
473 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
474 if let Some(ss) = prev_control_tlvs_ss.take() {
475 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
477 next_node_id: unblinded_pk_opt.unwrap(),
478 next_blinding_override: None,
482 prev_control_tlvs_ss = Some(control_tlvs_ss);
483 unblinded_path_idx += 1;
484 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
485 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
486 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
487 next_node_id: intro_node_id,
488 next_blinding_override: Some(blinding_pt),
489 })), control_tlvs_ss));
491 if let Some(encrypted_payload) = enc_payload_opt {
492 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(encrypted_payload)),
494 } else { debug_assert!(false); }
495 blinded_path_idx += 1;
496 } else if blinded_path_idx < num_blinded_hops - 1 && enc_payload_opt.is_some() {
497 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
499 blinded_path_idx += 1;
500 } else if let Some(encrypted_payload) = enc_payload_opt {
501 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
502 prev_control_tlvs_ss = Some(control_tlvs_ss);
505 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
506 onion_packet_keys.push(onion_utils::OnionKeys {
508 shared_secret: onion_packet_ss,
510 blinding_factor: [0; 32],
517 if let Some(control_tlvs) = final_control_tlvs {
518 payloads.push((Payload::Receive {
520 reply_path: reply_path.take(),
522 }, prev_control_tlvs_ss.unwrap()));
524 payloads.push((Payload::Receive {
525 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
526 reply_path: reply_path.take(),
528 }, prev_control_tlvs_ss.unwrap()));
531 Ok((payloads, onion_packet_keys))
534 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
535 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, ()> {
537 // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
538 // onion, but this should be used sparingly as it is reduces anonymity set, hence the
539 // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
540 let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
541 let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
542 SMALL_PACKET_HOP_DATA_LEN
543 } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
544 BIG_PACKET_HOP_DATA_LEN
545 } else { return Err(()) };
547 Ok(onion_utils::construct_onion_message_packet::<_, _>(
548 payloads, onion_keys, prng_seed, hop_data_len))