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;
19 use crate::blinded_path::message::{advance_path_by_one, ForwardTlvs, ReceiveTlvs};
20 use crate::blinded_path::utils;
21 use crate::sign::{EntropySource, KeysManager, NodeSigner, Recipient};
22 use crate::events::OnionMessageProvider;
23 use crate::ln::features::{InitFeatures, NodeFeatures};
24 use crate::ln::msgs::{self, OnionMessageHandler};
25 use crate::ln::onion_utils;
26 use crate::ln::peer_handler::IgnoringMessageHandler;
27 pub use super::packet::{CustomOnionMessageContents, OnionMessageContents};
28 use super::offers::OffersMessageHandler;
29 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
30 use crate::util::logger::Logger;
31 use crate::util::ser::Writeable;
35 use crate::sync::{Arc, Mutex};
36 use crate::prelude::*;
38 /// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be
39 /// used to retrieve invoices and fulfill invoice requests from [offers]. Currently, only sending
40 /// and receiving custom onion messages is supported.
45 /// # extern crate bitcoin;
46 /// # use bitcoin::hashes::_export::_core::time::Duration;
47 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
48 /// # use lightning::blinded_path::BlindedPath;
49 /// # use lightning::sign::KeysManager;
50 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
51 /// # use lightning::onion_message::{CustomOnionMessageContents, Destination, MessageRouter, OnionMessageContents, OnionMessagePath, OnionMessenger};
52 /// # use lightning::util::logger::{Logger, Record};
53 /// # use lightning::util::ser::{Writeable, Writer};
54 /// # use lightning::io;
55 /// # use std::sync::Arc;
56 /// # struct FakeLogger;
57 /// # impl Logger for FakeLogger {
58 /// # fn log(&self, record: &Record) { unimplemented!() }
60 /// # struct FakeMessageRouter {}
61 /// # impl MessageRouter for FakeMessageRouter {
62 /// # fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
63 /// # unimplemented!()
66 /// # let seed = [42u8; 32];
67 /// # let time = Duration::from_secs(123456);
68 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
69 /// # let logger = Arc::new(FakeLogger {});
70 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
71 /// # let secp_ctx = Secp256k1::new();
72 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
73 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
74 /// # let destination_node_id = hop_node_id1;
75 /// # let message_router = Arc::new(FakeMessageRouter {});
76 /// # let custom_message_handler = IgnoringMessageHandler {};
77 /// # let offers_message_handler = IgnoringMessageHandler {};
78 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
79 /// // ChannelManager.
80 /// let onion_messenger = OnionMessenger::new(
81 /// &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
82 /// &custom_message_handler
85 /// # struct YourCustomMessage {}
86 /// impl Writeable for YourCustomMessage {
87 /// fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
89 /// // Write your custom onion message to `w`
92 /// impl CustomOnionMessageContents for YourCustomMessage {
93 /// fn tlv_type(&self) -> u64 {
94 /// # let your_custom_message_type = 42;
95 /// your_custom_message_type
98 /// // Send a custom onion message to a node id.
99 /// let path = OnionMessagePath {
100 /// intermediate_nodes: vec![hop_node_id1, hop_node_id2],
101 /// destination: Destination::Node(destination_node_id),
103 /// let reply_path = None;
104 /// # let your_custom_message = YourCustomMessage {};
105 /// let message = OnionMessageContents::Custom(your_custom_message);
106 /// onion_messenger.send_onion_message(path, message, reply_path);
108 /// // Create a blinded path to yourself, for someone to send an onion message to.
109 /// # let your_node_id = hop_node_id1;
110 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
111 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
113 /// // Send a custom onion message to a blinded path.
114 /// let path = OnionMessagePath {
115 /// intermediate_nodes: vec![hop_node_id1, hop_node_id2],
116 /// destination: Destination::BlindedPath(blinded_path),
118 /// let reply_path = None;
119 /// # let your_custom_message = YourCustomMessage {};
120 /// let message = OnionMessageContents::Custom(your_custom_message);
121 /// onion_messenger.send_onion_message(path, message, reply_path);
124 /// [offers]: <https://github.com/lightning/bolts/pull/798>
125 /// [`OnionMessenger`]: crate::onion_message::OnionMessenger
126 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
128 ES::Target: EntropySource,
129 NS::Target: NodeSigner,
131 MR::Target: MessageRouter,
132 OMH::Target: OffersMessageHandler,
133 CMH:: Target: CustomOnionMessageHandler,
138 pending_messages: Mutex<HashMap<PublicKey, VecDeque<msgs::OnionMessage>>>,
139 secp_ctx: Secp256k1<secp256k1::All>,
145 /// A trait defining behavior for routing an [`OnionMessage`].
147 /// [`OnionMessage`]: msgs::OnionMessage
148 pub trait MessageRouter {
149 /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
151 /// [`OnionMessage`]: msgs::OnionMessage
153 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
154 ) -> Result<OnionMessagePath, ()>;
157 /// A [`MessageRouter`] that always fails.
158 pub struct DefaultMessageRouter;
160 impl MessageRouter for DefaultMessageRouter {
162 &self, _sender: PublicKey, _peers: Vec<PublicKey>, _destination: Destination
163 ) -> Result<OnionMessagePath, ()> {
168 /// A path for sending an [`msgs::OnionMessage`].
170 pub struct OnionMessagePath {
171 /// Nodes on the path between the sender and the destination.
172 pub intermediate_nodes: Vec<PublicKey>,
174 /// The recipient of the message.
175 pub destination: Destination,
178 /// The destination of an onion message.
180 pub enum Destination {
181 /// We're sending this onion message to a node.
183 /// We're sending this onion message to a blinded path.
184 BlindedPath(BlindedPath),
188 pub(super) fn num_hops(&self) -> usize {
190 Destination::Node(_) => 1,
191 Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
196 /// Errors that may occur when [sending an onion message].
198 /// [sending an onion message]: OnionMessenger::send_onion_message
199 #[derive(Debug, PartialEq, Eq)]
201 /// Errored computing onion message packet keys.
202 Secp256k1(secp256k1::Error),
203 /// Because implementations such as Eclair will drop onion messages where the message packet
204 /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
206 /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two
209 /// Our next-hop peer was offline or does not support onion message forwarding.
211 /// Onion message contents must have a TLV type >= 64.
213 /// Our next-hop peer's buffer was full or our total outbound buffer was full.
215 /// Failed to retrieve our node id from the provided [`NodeSigner`].
217 /// [`NodeSigner`]: crate::sign::NodeSigner
219 /// We attempted to send to a blinded path where we are the introduction node, and failed to
220 /// advance the blinded path to make the second hop the new introduction node. Either
221 /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
222 /// new blinding point, or we were attempting to send to ourselves.
223 BlindedPathAdvanceFailed,
226 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
227 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
228 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
229 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
232 /// See [`OnionMessenger`] for example usage.
234 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
235 /// [`CustomMessage`]: Self::CustomMessage
236 pub trait CustomOnionMessageHandler {
237 /// The message known to the handler. To support multiple message types, you may want to make this
238 /// an enum with a variant for each supported message.
239 type CustomMessage: CustomOnionMessageContents;
241 /// Called with the custom message that was received, returning a response to send, if any.
242 fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
244 /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
245 /// message type is unknown.
246 fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
249 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
250 OnionMessenger<ES, NS, L, MR, OMH, CMH>
252 ES::Target: EntropySource,
253 NS::Target: NodeSigner,
255 MR::Target: MessageRouter,
256 OMH::Target: OffersMessageHandler,
257 CMH::Target: CustomOnionMessageHandler,
259 /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
260 /// their respective handlers.
262 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
265 let mut secp_ctx = Secp256k1::new();
266 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
270 pending_messages: Mutex::new(HashMap::new()),
279 /// Send an onion message with contents `message` to the destination of `path`.
281 /// See [`OnionMessenger`] for example usage.
282 pub fn send_onion_message<T: CustomOnionMessageContents>(
283 &self, path: OnionMessagePath, message: OnionMessageContents<T>,
284 reply_path: Option<BlindedPath>
285 ) -> Result<(), SendError> {
286 let OnionMessagePath { intermediate_nodes, mut destination } = path;
287 if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
288 if blinded_hops.len() < 2 {
289 return Err(SendError::TooFewBlindedHops);
293 if message.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
295 // If we are sending straight to a blinded path and we are the introduction node, we need to
296 // advance the blinded path by 1 hop so the second hop is the new introduction node.
297 if intermediate_nodes.len() == 0 {
298 if let Destination::BlindedPath(ref mut blinded_path) = destination {
299 let our_node_id = self.node_signer.get_node_id(Recipient::Node)
300 .map_err(|()| SendError::GetNodeIdFailed)?;
301 if blinded_path.introduction_node_id == our_node_id {
302 advance_path_by_one(blinded_path, &self.node_signer, &self.secp_ctx)
303 .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
308 let blinding_secret_bytes = self.entropy_source.get_secure_random_bytes();
309 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
310 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
311 (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
314 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
315 Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
316 (introduction_node_id, blinding_point),
319 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
320 &self.secp_ctx, &intermediate_nodes, destination, message, reply_path, &blinding_secret)
321 .map_err(|e| SendError::Secp256k1(e))?;
323 let prng_seed = self.entropy_source.get_secure_random_bytes();
324 let onion_routing_packet = construct_onion_message_packet(
325 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
327 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
328 if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
329 match pending_per_peer_msgs.entry(introduction_node_id) {
330 hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
331 hash_map::Entry::Occupied(mut e) => {
332 e.get_mut().push_back(msgs::OnionMessage { blinding_point, onion_routing_packet });
338 fn respond_with_onion_message<T: CustomOnionMessageContents>(
339 &self, response: OnionMessageContents<T>, path_id: Option<[u8; 32]>,
340 reply_path: Option<BlindedPath>
342 let sender = match self.node_signer.get_node_id(Recipient::Node) {
343 Ok(node_id) => node_id,
346 self.logger, "Unable to retrieve node id when responding to onion message with \
347 path_id {:02x?}", path_id
353 let peers = self.pending_messages.lock().unwrap().keys().copied().collect();
355 let destination = match reply_path {
356 Some(reply_path) => Destination::BlindedPath(reply_path),
359 self.logger, "Missing reply path when responding to onion message with path_id \
366 let path = match self.message_router.find_path(sender, peers, destination) {
370 self.logger, "Failed to find path when responding to onion message with \
371 path_id {:02x?}", path_id
377 log_trace!(self.logger, "Responding to onion message with path_id {:02x?}", path_id);
379 if let Err(e) = self.send_onion_message(path, response, None) {
381 self.logger, "Failed responding to onion message with path_id {:02x?}: {:?}",
389 pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<msgs::OnionMessage>> {
390 let mut pending_msgs = self.pending_messages.lock().unwrap();
391 let mut msgs = HashMap::new();
392 // We don't want to disconnect the peers by removing them entirely from the original map, so we
393 // swap the pending message buffers individually.
394 for (peer_node_id, pending_messages) in &mut *pending_msgs {
395 msgs.insert(*peer_node_id, core::mem::take(pending_messages));
401 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<msgs::OnionMessage>>) -> bool {
402 const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
403 const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
404 let mut total_buffered_bytes = 0;
405 let mut peer_buffered_bytes = 0;
406 for (pk, peer_buf) in buffer {
408 let om_len = om.serialized_length();
409 if pk == peer_node_id {
410 peer_buffered_bytes += om_len;
412 total_buffered_bytes += om_len;
414 if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
415 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
424 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
425 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
427 ES::Target: EntropySource,
428 NS::Target: NodeSigner,
430 MR::Target: MessageRouter,
431 OMH::Target: OffersMessageHandler,
432 CMH::Target: CustomOnionMessageHandler,
434 /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
435 /// soon we'll delegate the onion message to a handler that can generate invoices or send
437 fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) {
438 let control_tlvs_ss = match self.node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
441 log_error!(self.logger, "Failed to retrieve node secret: {:?}", e);
445 let onion_decode_ss = {
446 let blinding_factor = {
447 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
448 hmac.input(control_tlvs_ss.as_ref());
449 Hmac::from_engine(hmac).into_inner()
451 match self.node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
452 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
454 Ok(ss) => ss.secret_bytes(),
456 log_trace!(self.logger, "Failed to compute onion packet shared secret");
461 match onion_utils::decode_next_untagged_hop(
462 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
463 (control_tlvs_ss, &*self.custom_handler, &*self.logger)
465 Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
466 message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
468 log_trace!(self.logger,
469 "Received an onion message with path_id {:02x?} and {} reply_path",
470 path_id, if reply_path.is_some() { "a" } else { "no" });
472 let response = match message {
473 OnionMessageContents::Offers(msg) => {
474 self.offers_handler.handle_message(msg)
475 .map(|msg| OnionMessageContents::Offers(msg))
477 OnionMessageContents::Custom(msg) => {
478 self.custom_handler.handle_custom_message(msg)
479 .map(|msg| OnionMessageContents::Custom(msg))
483 if let Some(response) = response {
484 self.respond_with_onion_message(response, path_id, reply_path);
487 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
488 next_node_id, next_blinding_override
489 })), Some((next_hop_hmac, new_packet_bytes)))) => {
490 // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
491 // blinded hop and this onion message is destined for us. In this situation, we should keep
492 // unwrapping the onion layers to get to the final payload. Since we don't have the option
493 // of creating blinded paths with dummy hops currently, we should be ok to not handle this
495 let new_pubkey = match onion_utils::next_hop_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
498 log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e);
502 let outgoing_packet = Packet {
504 public_key: new_pubkey,
505 hop_data: new_packet_bytes,
508 let onion_message = msgs::OnionMessage {
509 blinding_point: match next_blinding_override {
510 Some(blinding_point) => blinding_point,
512 match onion_utils::next_hop_pubkey(
513 &self.secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
517 log_trace!(self.logger, "Failed to compute next blinding point: {}", e);
523 onion_routing_packet: outgoing_packet,
526 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
527 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
528 log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
533 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
535 match pending_per_peer_msgs.entry(next_node_id) {
536 hash_map::Entry::Vacant(_) => {
537 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
540 hash_map::Entry::Occupied(mut e) => {
541 e.get_mut().push_back(onion_message);
542 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
547 log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e);
550 log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
555 fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
556 if init.features.supports_onion_messages() {
557 let mut peers = self.pending_messages.lock().unwrap();
558 peers.insert(their_node_id.clone(), VecDeque::new());
563 fn peer_disconnected(&self, their_node_id: &PublicKey) {
564 let mut pending_msgs = self.pending_messages.lock().unwrap();
565 pending_msgs.remove(their_node_id);
568 fn provided_node_features(&self) -> NodeFeatures {
569 let mut features = NodeFeatures::empty();
570 features.set_onion_messages_optional();
574 fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
575 let mut features = InitFeatures::empty();
576 features.set_onion_messages_optional();
581 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageProvider
582 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
584 ES::Target: EntropySource,
585 NS::Target: NodeSigner,
587 MR::Target: MessageRouter,
588 OMH::Target: OffersMessageHandler,
589 CMH::Target: CustomOnionMessageHandler,
591 fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
592 let mut pending_msgs = self.pending_messages.lock().unwrap();
593 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
594 return msgs.pop_front()
600 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
602 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
603 /// [`SimpleArcPeerManager`]. See their docs for more details.
605 /// This is not exported to bindings users as `Arc`s don't make sense in bindings.
607 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
608 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
609 pub type SimpleArcOnionMessenger<L> = OnionMessenger<
613 Arc<DefaultMessageRouter>,
614 IgnoringMessageHandler,
615 IgnoringMessageHandler
618 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
619 /// [`SimpleRefPeerManager`]. See their docs for more details.
621 /// This is not exported to bindings users as general type aliases don't make sense in bindings.
623 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
624 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
625 pub type SimpleRefOnionMessenger<'a, 'b, 'c, L> = OnionMessenger<
629 &'c DefaultMessageRouter,
630 IgnoringMessageHandler,
631 IgnoringMessageHandler
634 /// Construct onion packet payloads and keys for sending an onion message along the given
635 /// `unblinded_path` to the given `destination`.
636 fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
637 secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
638 message: OnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
639 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
640 let num_hops = unblinded_path.len() + destination.num_hops();
641 let mut payloads = Vec::with_capacity(num_hops);
642 let mut onion_packet_keys = Vec::with_capacity(num_hops);
644 let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
645 introduction_node_id, blinding_point, blinded_hops }) = &destination {
646 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
647 let num_unblinded_hops = num_hops - num_blinded_hops;
649 let mut unblinded_path_idx = 0;
650 let mut blinded_path_idx = 0;
651 let mut prev_control_tlvs_ss = None;
652 let mut final_control_tlvs = None;
653 utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
654 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
655 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
656 if let Some(ss) = prev_control_tlvs_ss.take() {
657 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
659 next_node_id: unblinded_pk_opt.unwrap(),
660 next_blinding_override: None,
664 prev_control_tlvs_ss = Some(control_tlvs_ss);
665 unblinded_path_idx += 1;
666 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
667 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
668 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
669 next_node_id: intro_node_id,
670 next_blinding_override: Some(blinding_pt),
671 })), control_tlvs_ss));
674 if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
675 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
677 blinded_path_idx += 1;
678 } else if let Some(encrypted_payload) = enc_payload_opt {
679 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
680 prev_control_tlvs_ss = Some(control_tlvs_ss);
683 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
684 onion_packet_keys.push(onion_utils::OnionKeys {
686 shared_secret: onion_packet_ss,
688 blinding_factor: [0; 32],
696 if let Some(control_tlvs) = final_control_tlvs {
697 payloads.push((Payload::Receive {
699 reply_path: reply_path.take(),
701 }, prev_control_tlvs_ss.unwrap()));
703 payloads.push((Payload::Receive {
704 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
705 reply_path: reply_path.take(),
707 }, prev_control_tlvs_ss.unwrap()));
710 Ok((payloads, onion_packet_keys))
713 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
714 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, ()> {
716 // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
717 // onion, but this should be used sparingly as it is reduces anonymity set, hence the
718 // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
719 let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
720 let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
721 SMALL_PACKET_HOP_DATA_LEN
722 } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
723 BIG_PACKET_HOP_DATA_LEN
724 } else { return Err(()) };
726 onion_utils::construct_onion_message_packet::<_, _>(
727 payloads, onion_keys, prng_seed, hop_data_len)