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::{EntropySource, KeysManager, NodeSigner, Recipient};
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_path::{BlindedPath, ForwardTlvs, ReceiveTlvs};
24 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::KeysManager;
47 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
48 /// # use lightning::onion_message::blinded_path::BlindedPath;
49 /// # use lightning::onion_message::messenger::{Destination, OnionMessenger};
50 /// # use lightning::onion_message::packet::{CustomOnionMessageContents, OnionMessageContents};
51 /// # use lightning::util::logger::{Logger, Record};
52 /// # use lightning::util::ser::{Writeable, Writer};
53 /// # use lightning::io;
54 /// # use std::sync::Arc;
55 /// # struct FakeLogger;
56 /// # impl Logger for FakeLogger {
57 /// # fn log(&self, record: &Record) { unimplemented!() }
59 /// # let seed = [42u8; 32];
60 /// # let time = Duration::from_secs(123456);
61 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
62 /// # let logger = Arc::new(FakeLogger {});
63 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
64 /// # let secp_ctx = Secp256k1::new();
65 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
66 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
67 /// # let destination_node_id = hop_node_id1;
68 /// # let your_custom_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, &your_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 intermediate_hops = [hop_node_id1, hop_node_id2];
88 /// let reply_path = None;
89 /// # let your_custom_message = YourCustomMessage {};
90 /// let message = OnionMessageContents::Custom(your_custom_message);
91 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::Node(destination_node_id), message, reply_path);
93 /// // Create a blinded path to yourself, for someone to send an onion message to.
94 /// # let your_node_id = hop_node_id1;
95 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
96 /// let blinded_path = BlindedPath::new(&hops, &keys_manager, &secp_ctx).unwrap();
98 /// // Send a custom onion message to a blinded path.
99 /// # let intermediate_hops = [hop_node_id1, hop_node_id2];
100 /// let reply_path = None;
101 /// # let your_custom_message = YourCustomMessage {};
102 /// let message = OnionMessageContents::Custom(your_custom_message);
103 /// onion_messenger.send_onion_message(&intermediate_hops, Destination::BlindedPath(blinded_path), message, reply_path);
106 /// [offers]: <https://github.com/lightning/bolts/pull/798>
107 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
108 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, CMH: Deref>
109 where ES::Target: EntropySource,
110 NS::Target: NodeSigner,
112 CMH:: Target: CustomOnionMessageHandler,
117 pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
118 secp_ctx: Secp256k1<secp256k1::All>,
121 // invoice_handler: InvoiceHandler,
124 /// The destination of an onion message.
125 pub enum Destination {
126 /// We're sending this onion message to a node.
128 /// We're sending this onion message to a blinded path.
129 BlindedPath(BlindedPath),
133 pub(super) fn num_hops(&self) -> usize {
135 Destination::Node(_) => 1,
136 Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
141 /// Errors that may occur when [sending an onion message].
143 /// [sending an onion message]: OnionMessenger::send_onion_message
144 #[derive(Debug, PartialEq, Eq)]
146 /// Errored computing onion message packet keys.
147 Secp256k1(secp256k1::Error),
148 /// Because implementations such as Eclair will drop onion messages where the message packet
149 /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
151 /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two
154 /// Our next-hop peer was offline or does not support onion message forwarding.
156 /// Onion message contents must have a TLV type >= 64.
158 /// Our next-hop peer's buffer was full or our total outbound buffer was full.
160 /// Failed to retrieve our node id from the provided [`NodeSigner`].
162 /// [`NodeSigner`]: crate::chain::keysinterface::NodeSigner
164 /// We attempted to send to a blinded path where we are the introduction node, and failed to
165 /// advance the blinded path to make the second hop the new introduction node. Either
166 /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
167 /// new blinding point, or we were attempting to send to ourselves.
168 BlindedPathAdvanceFailed,
171 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
172 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
173 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
174 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
177 /// See [`OnionMessenger`] for example usage.
179 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
180 /// [`CustomMessage`]: Self::CustomMessage
181 pub trait CustomOnionMessageHandler {
182 /// The message known to the handler. To support multiple message types, you may want to make this
183 /// an enum with a variant for each supported message.
184 type CustomMessage: CustomOnionMessageContents;
185 /// Called with the custom message that was received.
186 fn handle_custom_message(&self, msg: Self::CustomMessage);
187 /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
188 /// message type is unknown.
189 fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
192 impl<ES: Deref, NS: Deref, L: Deref, CMH: Deref> OnionMessenger<ES, NS, L, CMH>
193 where ES::Target: EntropySource,
194 NS::Target: NodeSigner,
196 CMH::Target: CustomOnionMessageHandler,
198 /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
199 /// their respective handlers.
200 pub fn new(entropy_source: ES, node_signer: NS, logger: L, custom_handler: CMH) -> Self {
201 let mut secp_ctx = Secp256k1::new();
202 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
206 pending_messages: Mutex::new(HashMap::new()),
213 /// Send an onion message with contents `message` to `destination`, routing it through `intermediate_nodes`.
214 /// See [`OnionMessenger`] for example usage.
215 pub fn send_onion_message<T: CustomOnionMessageContents>(&self, intermediate_nodes: &[PublicKey], mut destination: Destination, message: OnionMessageContents<T>, reply_path: Option<BlindedPath>) -> Result<(), SendError> {
216 if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
217 if blinded_hops.len() < 2 {
218 return Err(SendError::TooFewBlindedHops);
221 let OnionMessageContents::Custom(ref msg) = message;
222 if msg.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
224 // If we are sending straight to a blinded path and we are the introduction node, we need to
225 // advance the blinded path by 1 hop so the second hop is the new introduction node.
226 if intermediate_nodes.len() == 0 {
227 if let Destination::BlindedPath(ref mut blinded_path) = destination {
228 let our_node_id = self.node_signer.get_node_id(Recipient::Node)
229 .map_err(|()| SendError::GetNodeIdFailed)?;
230 if blinded_path.introduction_node_id == our_node_id {
231 blinded_path.advance_by_one(&self.node_signer, &self.secp_ctx)
232 .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
237 let blinding_secret_bytes = self.entropy_source.get_secure_random_bytes();
238 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
239 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
240 (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
243 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
244 Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
245 (introduction_node_id, blinding_point),
248 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
249 &self.secp_ctx, intermediate_nodes, destination, message, reply_path, &blinding_secret)
250 .map_err(|e| SendError::Secp256k1(e))?;
252 let prng_seed = self.entropy_source.get_secure_random_bytes();
253 let onion_routing_packet = construct_onion_message_packet(
254 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
256 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
257 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
258 match pending_per_peer_msgs.entry(introduction_node_id) {
259 hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
260 hash_map::Entry::Occupied(mut e) => {
261 e.get_mut().push_back(msgs::OnionMessage { blinding_point, onion_routing_packet });
268 pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
269 let mut pending_msgs = self.pending_messages.lock().unwrap();
270 let mut msgs = HashMap::new();
271 // We don't want to disconnect the peers by removing them entirely from the original map, so we
272 // swap the pending message buffers individually.
273 for (peer_node_id, pending_messages) in &mut *pending_msgs {
274 msgs.insert(*peer_node_id, core::mem::take(pending_messages));
280 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
281 const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
282 const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
283 let mut total_buffered_bytes = 0;
284 let mut peer_buffered_bytes = 0;
285 for (pk, peer_buf) in buffer {
287 let om_len = om.serialized_length();
288 if pk == peer_node_id {
289 peer_buffered_bytes += om_len;
291 total_buffered_bytes += om_len;
293 if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
294 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
303 impl<ES: Deref, NS: Deref, L: Deref, CMH: Deref> OnionMessageHandler for OnionMessenger<ES, NS, L, CMH>
304 where ES::Target: EntropySource,
305 NS::Target: NodeSigner,
307 CMH::Target: CustomOnionMessageHandler + Sized,
309 /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
310 /// soon we'll delegate the onion message to a handler that can generate invoices or send
312 fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
313 let control_tlvs_ss = match self.node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
316 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
320 let onion_decode_ss = {
321 let blinding_factor = {
322 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
323 hmac.input(control_tlvs_ss.as_ref());
324 Hmac::from_engine(hmac).into_inner()
326 match self.node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
327 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
329 Ok(ss) => ss.secret_bytes(),
331 log_trace!(self.logger, "Failed to compute onion packet shared secret");
336 match onion_utils::decode_next_untagged_hop(onion_decode_ss, &msg.onion_routing_packet.hop_data[..],
337 msg.onion_routing_packet.hmac, (control_tlvs_ss, &*self.custom_handler))
339 Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
340 message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
342 log_info!(self.logger,
343 "Received an onion message with path_id {:02x?} and {} reply_path",
344 path_id, if reply_path.is_some() { "a" } else { "no" });
346 OnionMessageContents::Custom(msg) => self.custom_handler.handle_custom_message(msg),
349 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
350 next_node_id, next_blinding_override
351 })), Some((next_hop_hmac, new_packet_bytes)))) => {
352 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
353 // blinded hop and this onion message is destined for us. In this situation, we should keep
354 // unwrapping the onion layers to get to the final payload. Since we don't have the option
355 // of creating blinded paths with dummy hops currently, we should be ok to not handle this
357 let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
360 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
364 let outgoing_packet = Packet {
366 public_key: new_pubkey,
367 hop_data: new_packet_bytes,
370 let onion_message = msgs::OnionMessage {
371 blinding_point: match next_blinding_override {
372 Some(blinding_point) => blinding_point,
374 let blinding_factor = {
375 let mut sha = Sha256::engine();
376 sha.input(&msg.blinding_point.serialize()[..]);
377 sha.input(control_tlvs_ss.as_ref());
378 Sha256::from_engine(sha).into_inner()
380 let next_blinding_point = msg.blinding_point;
381 match next_blinding_point.mul_tweak(&self.secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) {
384 log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
390 onion_routing_packet: outgoing_packet,
393 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
394 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
395 log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
400 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
402 match pending_per_peer_msgs.entry(next_node_id) {
403 hash_map::Entry::Vacant(_) => {
404 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
407 hash_map::Entry::Occupied(mut e) => {
408 e.get_mut().push_back(onion_message);
409 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
414 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
417 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
422 fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
423 if init.features.supports_onion_messages() {
424 let mut peers = self.pending_messages.lock().unwrap();
425 peers.insert(their_node_id.clone(), VecDeque::new());
430 fn peer_disconnected(&self, their_node_id: &PublicKey) {
431 let mut pending_msgs = self.pending_messages.lock().unwrap();
432 pending_msgs.remove(their_node_id);
435 fn provided_node_features(&self) -> NodeFeatures {
436 let mut features = NodeFeatures::empty();
437 features.set_onion_messages_optional();
441 fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
442 let mut features = InitFeatures::empty();
443 features.set_onion_messages_optional();
448 impl<ES: Deref, NS: Deref, L: Deref, CMH: Deref> OnionMessageProvider for OnionMessenger<ES, NS, L, CMH>
449 where ES::Target: EntropySource,
450 NS::Target: NodeSigner,
452 CMH::Target: CustomOnionMessageHandler,
454 fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
455 let mut pending_msgs = self.pending_messages.lock().unwrap();
456 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
457 return msgs.pop_front()
463 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
465 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
466 /// [`SimpleArcPeerManager`]. See their docs for more details.
468 /// (C-not exported) as `Arc`s don't make sense in bindings.
470 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
471 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
472 pub type SimpleArcOnionMessenger<L> = OnionMessenger<Arc<KeysManager>, Arc<KeysManager>, Arc<L>, IgnoringMessageHandler>;
473 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
474 /// [`SimpleRefPeerManager`]. See their docs for more details.
476 /// (C-not exported) as general type aliases don't make sense in bindings.
478 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
479 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
480 pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<&'a KeysManager, &'a KeysManager, &'b L, IgnoringMessageHandler>;
482 /// Construct onion packet payloads and keys for sending an onion message along the given
483 /// `unblinded_path` to the given `destination`.
484 fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
485 secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
486 message: OnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
487 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
488 let num_hops = unblinded_path.len() + destination.num_hops();
489 let mut payloads = Vec::with_capacity(num_hops);
490 let mut onion_packet_keys = Vec::with_capacity(num_hops);
492 let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
493 introduction_node_id, blinding_point, blinded_hops }) = &destination {
494 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
495 let num_unblinded_hops = num_hops - num_blinded_hops;
497 let mut unblinded_path_idx = 0;
498 let mut blinded_path_idx = 0;
499 let mut prev_control_tlvs_ss = None;
500 let mut final_control_tlvs = None;
501 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| {
502 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
503 if let Some(ss) = prev_control_tlvs_ss.take() {
504 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
506 next_node_id: unblinded_pk_opt.unwrap(),
507 next_blinding_override: None,
511 prev_control_tlvs_ss = Some(control_tlvs_ss);
512 unblinded_path_idx += 1;
513 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
514 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
515 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
516 next_node_id: intro_node_id,
517 next_blinding_override: Some(blinding_pt),
518 })), control_tlvs_ss));
521 if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
522 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
524 blinded_path_idx += 1;
525 } else if let Some(encrypted_payload) = enc_payload_opt {
526 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
527 prev_control_tlvs_ss = Some(control_tlvs_ss);
530 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
531 onion_packet_keys.push(onion_utils::OnionKeys {
533 shared_secret: onion_packet_ss,
535 blinding_factor: [0; 32],
542 if let Some(control_tlvs) = final_control_tlvs {
543 payloads.push((Payload::Receive {
545 reply_path: reply_path.take(),
547 }, prev_control_tlvs_ss.unwrap()));
549 payloads.push((Payload::Receive {
550 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
551 reply_path: reply_path.take(),
553 }, prev_control_tlvs_ss.unwrap()));
556 Ok((payloads, onion_packet_keys))
559 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
560 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, ()> {
562 // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
563 // onion, but this should be used sparingly as it is reduces anonymity set, hence the
564 // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
565 let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
566 let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
567 SMALL_PACKET_HOP_DATA_LEN
568 } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
569 BIG_PACKET_HOP_DATA_LEN
570 } else { return Err(()) };
572 Ok(onion_utils::construct_onion_message_packet::<_, _>(
573 payloads, onion_keys, prng_seed, hop_data_len))