Merge pull request #2636 from slanesuke/impl-ToSocketAddrs-for-Hostname
[rust-lightning] / lightning / src / onion_message / messenger.rs
1 // This file is Copyright its original authors, visible in version control
2 // history.
3 //
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
8 // licenses.
9
10 //! LDK sends, receives, and forwards onion messages via the [`OnionMessenger`]. See its docs for
11 //! more information.
12
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};
17
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::ln::features::{InitFeatures, NodeFeatures};
23 use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler};
24 use crate::ln::onion_utils;
25 use crate::ln::peer_handler::IgnoringMessageHandler;
26 pub use super::packet::OnionMessageContents;
27 use super::packet::ParsedOnionMessageContents;
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;
32
33 use core::fmt;
34 use core::ops::Deref;
35 use crate::io;
36 use crate::sync::{Arc, Mutex};
37 use crate::prelude::*;
38
39 /// A sender, receiver and forwarder of [`OnionMessage`]s.
40 ///
41 /// # Handling Messages
42 ///
43 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
44 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
45 /// available handlers are:
46 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
47 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
48 ///
49 /// # Sending Messages
50 ///
51 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
52 /// a message, the matched handler may return a response message which `OnionMessenger` will send
53 /// on its behalf.
54 ///
55 /// # Example
56 ///
57 /// ```
58 /// # extern crate bitcoin;
59 /// # use bitcoin::hashes::_export::_core::time::Duration;
60 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
61 /// # use lightning::blinded_path::BlindedPath;
62 /// # use lightning::sign::KeysManager;
63 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
64 /// # use lightning::onion_message::{OnionMessageContents, Destination, MessageRouter, OnionMessagePath, OnionMessenger};
65 /// # use lightning::util::logger::{Logger, Record};
66 /// # use lightning::util::ser::{Writeable, Writer};
67 /// # use lightning::io;
68 /// # use std::sync::Arc;
69 /// # struct FakeLogger;
70 /// # impl Logger for FakeLogger {
71 /// #     fn log(&self, record: &Record) { unimplemented!() }
72 /// # }
73 /// # struct FakeMessageRouter {}
74 /// # impl MessageRouter for FakeMessageRouter {
75 /// #     fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
76 /// #         unimplemented!()
77 /// #     }
78 /// # }
79 /// # let seed = [42u8; 32];
80 /// # let time = Duration::from_secs(123456);
81 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
82 /// # let logger = Arc::new(FakeLogger {});
83 /// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
84 /// # let secp_ctx = Secp256k1::new();
85 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
86 /// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1);
87 /// # let destination_node_id = hop_node_id1;
88 /// # let message_router = Arc::new(FakeMessageRouter {});
89 /// # let custom_message_handler = IgnoringMessageHandler {};
90 /// # let offers_message_handler = IgnoringMessageHandler {};
91 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
92 /// // ChannelManager.
93 /// let onion_messenger = OnionMessenger::new(
94 ///     &keys_manager, &keys_manager, logger, message_router, &offers_message_handler,
95 ///     &custom_message_handler
96 /// );
97 ///
98 /// # struct YourCustomMessage {}
99 /// impl Writeable for YourCustomMessage {
100 ///     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
101 ///             # Ok(())
102 ///             // Write your custom onion message to `w`
103 ///     }
104 /// }
105 /// impl OnionMessageContents for YourCustomMessage {
106 ///     fn tlv_type(&self) -> u64 {
107 ///             # let your_custom_message_type = 42;
108 ///             your_custom_message_type
109 ///     }
110 /// }
111 /// // Send a custom onion message to a node id.
112 /// let path = OnionMessagePath {
113 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
114 ///     destination: Destination::Node(destination_node_id),
115 /// };
116 /// let reply_path = None;
117 /// # let message = YourCustomMessage {};
118 /// onion_messenger.send_onion_message(path, message, reply_path);
119 ///
120 /// // Create a blinded path to yourself, for someone to send an onion message to.
121 /// # let your_node_id = hop_node_id1;
122 /// let hops = [hop_node_id3, hop_node_id4, your_node_id];
123 /// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
124 ///
125 /// // Send a custom onion message to a blinded path.
126 /// let path = OnionMessagePath {
127 ///     intermediate_nodes: vec![hop_node_id1, hop_node_id2],
128 ///     destination: Destination::BlindedPath(blinded_path),
129 /// };
130 /// let reply_path = None;
131 /// # let message = YourCustomMessage {};
132 /// onion_messenger.send_onion_message(path, message, reply_path);
133 /// ```
134 ///
135 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
136 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
137 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
138 where
139         ES::Target: EntropySource,
140         NS::Target: NodeSigner,
141         L::Target: Logger,
142         MR::Target: MessageRouter,
143         OMH::Target: OffersMessageHandler,
144         CMH:: Target: CustomOnionMessageHandler,
145 {
146         entropy_source: ES,
147         node_signer: NS,
148         logger: L,
149         pending_messages: Mutex<HashMap<PublicKey, VecDeque<OnionMessage>>>,
150         secp_ctx: Secp256k1<secp256k1::All>,
151         message_router: MR,
152         offers_handler: OMH,
153         custom_handler: CMH,
154 }
155
156 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
157 ///
158 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
159 /// enqueued for sending.
160 pub struct PendingOnionMessage<T: OnionMessageContents> {
161         /// The message contents to send in an [`OnionMessage`].
162         pub contents: T,
163
164         /// The destination of the message.
165         pub destination: Destination,
166
167         /// A reply path to include in the [`OnionMessage`] for a response.
168         pub reply_path: Option<BlindedPath>,
169 }
170
171 /// A trait defining behavior for routing an [`OnionMessage`].
172 pub trait MessageRouter {
173         /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
174         fn find_path(
175                 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
176         ) -> Result<OnionMessagePath, ()>;
177 }
178
179 /// A [`MessageRouter`] that always fails.
180 pub struct DefaultMessageRouter;
181
182 impl MessageRouter for DefaultMessageRouter {
183         fn find_path(
184                 &self, _sender: PublicKey, _peers: Vec<PublicKey>, _destination: Destination
185         ) -> Result<OnionMessagePath, ()> {
186                 Err(())
187         }
188 }
189
190 /// A path for sending an [`OnionMessage`].
191 #[derive(Clone)]
192 pub struct OnionMessagePath {
193         /// Nodes on the path between the sender and the destination.
194         pub intermediate_nodes: Vec<PublicKey>,
195
196         /// The recipient of the message.
197         pub destination: Destination,
198 }
199
200 /// The destination of an onion message.
201 #[derive(Clone)]
202 pub enum Destination {
203         /// We're sending this onion message to a node.
204         Node(PublicKey),
205         /// We're sending this onion message to a blinded path.
206         BlindedPath(BlindedPath),
207 }
208
209 impl Destination {
210         pub(super) fn num_hops(&self) -> usize {
211                 match self {
212                         Destination::Node(_) => 1,
213                         Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
214                 }
215         }
216 }
217
218 /// Errors that may occur when [sending an onion message].
219 ///
220 /// [sending an onion message]: OnionMessenger::send_onion_message
221 #[derive(Debug, PartialEq, Eq)]
222 pub enum SendError {
223         /// Errored computing onion message packet keys.
224         Secp256k1(secp256k1::Error),
225         /// Because implementations such as Eclair will drop onion messages where the message packet
226         /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
227         TooBigPacket,
228         /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
229         /// hops.
230         TooFewBlindedHops,
231         /// Our next-hop peer was offline or does not support onion message forwarding.
232         InvalidFirstHop,
233         /// Onion message contents must have a TLV type >= 64.
234         InvalidMessage,
235         /// Our next-hop peer's buffer was full or our total outbound buffer was full.
236         BufferFull,
237         /// Failed to retrieve our node id from the provided [`NodeSigner`].
238         ///
239         /// [`NodeSigner`]: crate::sign::NodeSigner
240         GetNodeIdFailed,
241         /// We attempted to send to a blinded path where we are the introduction node, and failed to
242         /// advance the blinded path to make the second hop the new introduction node. Either
243         /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
244         /// new blinding point, or we were attempting to send to ourselves.
245         BlindedPathAdvanceFailed,
246 }
247
248 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
249 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
250 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
251 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
252 /// message types.
253 ///
254 /// See [`OnionMessenger`] for example usage.
255 ///
256 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
257 /// [`CustomMessage`]: Self::CustomMessage
258 pub trait CustomOnionMessageHandler {
259         /// The message known to the handler. To support multiple message types, you may want to make this
260         /// an enum with a variant for each supported message.
261         type CustomMessage: OnionMessageContents;
262
263         /// Called with the custom message that was received, returning a response to send, if any.
264         ///
265         /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
266         fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
267
268         /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
269         /// message type is unknown.
270         fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
271
272         /// Releases any [`Self::CustomMessage`]s that need to be sent.
273         ///
274         /// Typically, this is used for messages initiating a message flow rather than in response to
275         /// another message. The latter should use the return value of [`Self::handle_custom_message`].
276         fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
277 }
278
279 /// A processed incoming onion message, containing either a Forward (another onion message)
280 /// or a Receive payload with decrypted contents.
281 pub enum PeeledOnion<T: OnionMessageContents> {
282         /// Forwarded onion, with the next node id and a new onion
283         Forward(PublicKey, OnionMessage),
284         /// Received onion message, with decrypted contents, path_id, and reply path
285         Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
286 }
287
288 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
289 /// `path`.
290 ///
291 /// Returns both the node id of the peer to send the message to and the message itself.
292 pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
293         entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
294         path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
295 ) -> Result<(PublicKey, OnionMessage), SendError>
296 where
297         ES::Target: EntropySource,
298         NS::Target: NodeSigner,
299 {
300         let OnionMessagePath { intermediate_nodes, mut destination } = path;
301         if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
302                 if blinded_hops.is_empty() {
303                         return Err(SendError::TooFewBlindedHops);
304                 }
305         }
306
307         if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
308
309         // If we are sending straight to a blinded path and we are the introduction node, we need to
310         // advance the blinded path by 1 hop so the second hop is the new introduction node.
311         if intermediate_nodes.len() == 0 {
312                 if let Destination::BlindedPath(ref mut blinded_path) = destination {
313                         let our_node_id = node_signer.get_node_id(Recipient::Node)
314                                 .map_err(|()| SendError::GetNodeIdFailed)?;
315                         if blinded_path.introduction_node_id == our_node_id {
316                                 advance_path_by_one(blinded_path, node_signer, &secp_ctx)
317                                         .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
318                         }
319                 }
320         }
321
322         let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
323         let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
324         let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
325                 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
326         } else {
327                 match destination {
328                         Destination::Node(pk) => (pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
329                         Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) =>
330                                 (introduction_node_id, blinding_point),
331                 }
332         };
333         let (packet_payloads, packet_keys) = packet_payloads_and_keys(
334                 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret)
335                 .map_err(|e| SendError::Secp256k1(e))?;
336
337         let prng_seed = entropy_source.get_secure_random_bytes();
338         let onion_routing_packet = construct_onion_message_packet(
339                 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
340
341         Ok((first_node_id, OnionMessage {
342                 blinding_point,
343                 onion_routing_packet
344         }))
345 }
346
347 /// Decode one layer of an incoming [`OnionMessage`].
348 ///
349 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
350 /// receiver.
351 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
352         msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
353         custom_handler: CMH,
354 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
355 where
356         NS::Target: NodeSigner,
357         L::Target: Logger,
358         CMH::Target: CustomOnionMessageHandler,
359 {
360         let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
361                 Ok(ss) => ss,
362                 Err(e) =>  {
363                         log_error!(logger, "Failed to retrieve node secret: {:?}", e);
364                         return Err(());
365                 }
366         };
367         let onion_decode_ss = {
368                 let blinding_factor = {
369                         let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
370                         hmac.input(control_tlvs_ss.as_ref());
371                         Hmac::from_engine(hmac).into_inner()
372                 };
373                 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
374                         Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
375                 {
376                         Ok(ss) => ss.secret_bytes(),
377                         Err(()) => {
378                                 log_trace!(logger, "Failed to compute onion packet shared secret");
379                                 return Err(());
380                         }
381                 }
382         };
383         match onion_utils::decode_next_untagged_hop(
384                 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
385                 (control_tlvs_ss, custom_handler.deref(), logger.deref())
386         ) {
387                 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
388                         message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
389                 }, None)) => {
390                         Ok(PeeledOnion::Receive(message, path_id, reply_path))
391                 },
392                 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
393                         next_node_id, next_blinding_override
394                 })), Some((next_hop_hmac, new_packet_bytes)))) => {
395                         // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy
396                         // blinded hop and this onion message is destined for us. In this situation, we should keep
397                         // unwrapping the onion layers to get to the final payload. Since we don't have the option
398                         // of creating blinded paths with dummy hops currently, we should be ok to not handle this
399                         // for now.
400                         let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
401                                 Ok(pk) => pk,
402                                 Err(e) => {
403                                         log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
404                                         return Err(())
405                                 }
406                         };
407                         let outgoing_packet = Packet {
408                                 version: 0,
409                                 public_key: new_pubkey,
410                                 hop_data: new_packet_bytes,
411                                 hmac: next_hop_hmac,
412                         };
413                         let onion_message = OnionMessage {
414                                 blinding_point: match next_blinding_override {
415                                         Some(blinding_point) => blinding_point,
416                                         None => {
417                                                 match onion_utils::next_hop_pubkey(
418                                                         &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
419                                                 ) {
420                                                         Ok(bp) => bp,
421                                                         Err(e) => {
422                                                                 log_trace!(logger, "Failed to compute next blinding point: {}", e);
423                                                                 return Err(())
424                                                         }
425                                                 }
426                                         }
427                                 },
428                                 onion_routing_packet: outgoing_packet,
429                         };
430
431                         Ok(PeeledOnion::Forward(next_node_id, onion_message))
432                 },
433                 Err(e) => {
434                         log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
435                         Err(())
436                 },
437                 _ => {
438                         log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
439                         Err(())
440                 },
441         }
442 }
443
444 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref>
445 OnionMessenger<ES, NS, L, MR, OMH, CMH>
446 where
447         ES::Target: EntropySource,
448         NS::Target: NodeSigner,
449         L::Target: Logger,
450         MR::Target: MessageRouter,
451         OMH::Target: OffersMessageHandler,
452         CMH::Target: CustomOnionMessageHandler,
453 {
454         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
455         /// their respective handlers.
456         pub fn new(
457                 entropy_source: ES, node_signer: NS, logger: L, message_router: MR, offers_handler: OMH,
458                 custom_handler: CMH
459         ) -> Self {
460                 let mut secp_ctx = Secp256k1::new();
461                 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
462                 OnionMessenger {
463                         entropy_source,
464                         node_signer,
465                         pending_messages: Mutex::new(HashMap::new()),
466                         secp_ctx,
467                         logger,
468                         message_router,
469                         offers_handler,
470                         custom_handler,
471                 }
472         }
473
474         /// Sends an [`OnionMessage`] with the given `contents` for sending to the destination of
475         /// `path`.
476         ///
477         /// See [`OnionMessenger`] for example usage.
478         pub fn send_onion_message<T: OnionMessageContents>(
479                 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
480         ) -> Result<(), SendError> {
481                 let (first_node_id, onion_msg) = create_onion_message(
482                         &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
483                 )?;
484
485                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
486                 if outbound_buffer_full(&first_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) }
487                 match pending_per_peer_msgs.entry(first_node_id) {
488                         hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop),
489                         hash_map::Entry::Occupied(mut e) => {
490                                 e.get_mut().push_back(onion_msg);
491                                 Ok(())
492                         }
493                 }
494         }
495
496         fn handle_onion_message_response<T: OnionMessageContents>(
497                 &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
498         ) {
499                 if let Some(response) = response {
500                         match reply_path {
501                                 Some(reply_path) => {
502                                         self.find_path_and_enqueue_onion_message(
503                                                 response, Destination::BlindedPath(reply_path), None, log_suffix
504                                         );
505                                 },
506                                 None => {
507                                         log_trace!(self.logger, "Missing reply path {}", log_suffix);
508                                 },
509                         }
510                 }
511         }
512
513         fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
514                 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
515                 log_suffix: fmt::Arguments
516         ) {
517                 let sender = match self.node_signer.get_node_id(Recipient::Node) {
518                         Ok(node_id) => node_id,
519                         Err(_) => {
520                                 log_warn!(self.logger, "Unable to retrieve node id {}", log_suffix);
521                                 return;
522                         }
523                 };
524
525                 let peers = self.pending_messages.lock().unwrap().keys().copied().collect();
526                 let path = match self.message_router.find_path(sender, peers, destination) {
527                         Ok(path) => path,
528                         Err(()) => {
529                                 log_trace!(self.logger, "Failed to find path {}", log_suffix);
530                                 return;
531                         },
532                 };
533
534                 log_trace!(self.logger, "Sending onion message {}", log_suffix);
535
536                 if let Err(e) = self.send_onion_message(path, contents, reply_path) {
537                         log_trace!(self.logger, "Failed sending onion message {}: {:?}", log_suffix, e);
538                         return;
539                 }
540         }
541
542         #[cfg(test)]
543         pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
544                 let mut pending_msgs = self.pending_messages.lock().unwrap();
545                 let mut msgs = HashMap::new();
546                 // We don't want to disconnect the peers by removing them entirely from the original map, so we
547                 // swap the pending message buffers individually.
548                 for (peer_node_id, pending_messages) in &mut *pending_msgs {
549                         msgs.insert(*peer_node_id, core::mem::take(pending_messages));
550                 }
551                 msgs
552         }
553 }
554
555 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, VecDeque<OnionMessage>>) -> bool {
556         const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
557         const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
558         let mut total_buffered_bytes = 0;
559         let mut peer_buffered_bytes = 0;
560         for (pk, peer_buf) in buffer {
561                 for om in peer_buf {
562                         let om_len = om.serialized_length();
563                         if pk == peer_node_id {
564                                 peer_buffered_bytes += om_len;
565                         }
566                         total_buffered_bytes += om_len;
567
568                         if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
569                                 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
570                         {
571                                 return true
572                         }
573                 }
574         }
575         false
576 }
577
578 impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
579 for OnionMessenger<ES, NS, L, MR, OMH, CMH>
580 where
581         ES::Target: EntropySource,
582         NS::Target: NodeSigner,
583         L::Target: Logger,
584         MR::Target: MessageRouter,
585         OMH::Target: OffersMessageHandler,
586         CMH::Target: CustomOnionMessageHandler,
587 {
588         fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
589                 match peel_onion_message(
590                         msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
591                 ) {
592                         Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
593                                 log_trace!(self.logger,
594                                         "Received an onion message with path_id {:02x?} and {} reply_path",
595                                                 path_id, if reply_path.is_some() { "a" } else { "no" });
596
597                                 match message {
598                                         ParsedOnionMessageContents::Offers(msg) => {
599                                                 let response = self.offers_handler.handle_message(msg);
600                                                 self.handle_onion_message_response(
601                                                         response, reply_path, format_args!(
602                                                                 "when responding to Offers onion message with path_id {:02x?}",
603                                                                 path_id
604                                                         )
605                                                 );
606                                         },
607                                         ParsedOnionMessageContents::Custom(msg) => {
608                                                 let response = self.custom_handler.handle_custom_message(msg);
609                                                 self.handle_onion_message_response(
610                                                         response, reply_path, format_args!(
611                                                                 "when responding to Custom onion message with path_id {:02x?}",
612                                                                 path_id
613                                                         )
614                                                 );
615                                         },
616                                 }
617                         },
618                         Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
619                                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
620                                 if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) {
621                                         log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id);
622                                         return
623                                 }
624
625                                 #[cfg(fuzzing)]
626                                 pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new);
627
628                                 match pending_per_peer_msgs.entry(next_node_id) {
629                                         hash_map::Entry::Vacant(_) => {
630                                                 log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id);
631                                                 return
632                                         },
633                                         hash_map::Entry::Occupied(mut e) => {
634                                                 e.get_mut().push_back(onion_message);
635                                                 log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id);
636                                         }
637                                 }
638                         },
639                         Err(e) => {
640                                 log_error!(self.logger, "Failed to process onion message {:?}", e);
641                         }
642                 }
643         }
644
645         fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
646                 if init.features.supports_onion_messages() {
647                         let mut peers = self.pending_messages.lock().unwrap();
648                         peers.insert(their_node_id.clone(), VecDeque::new());
649                 }
650                 Ok(())
651         }
652
653         fn peer_disconnected(&self, their_node_id: &PublicKey) {
654                 let mut pending_msgs = self.pending_messages.lock().unwrap();
655                 pending_msgs.remove(their_node_id);
656         }
657
658         fn provided_node_features(&self) -> NodeFeatures {
659                 let mut features = NodeFeatures::empty();
660                 features.set_onion_messages_optional();
661                 features
662         }
663
664         fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
665                 let mut features = InitFeatures::empty();
666                 features.set_onion_messages_optional();
667                 features
668         }
669
670         // Before returning any messages to send for the peer, this method will see if any messages were
671         // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
672         // node, and then enqueue the message for sending to the first peer in the full path.
673         fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
674                 // Enqueue any initiating `OffersMessage`s to send.
675                 for message in self.offers_handler.release_pending_messages() {
676                         let PendingOnionMessage { contents, destination, reply_path } = message;
677                         self.find_path_and_enqueue_onion_message(
678                                 contents, destination, reply_path, format_args!("when sending OffersMessage")
679                         );
680                 }
681
682                 // Enqueue any initiating `CustomMessage`s to send.
683                 for message in self.custom_handler.release_pending_custom_messages() {
684                         let PendingOnionMessage { contents, destination, reply_path } = message;
685                         self.find_path_and_enqueue_onion_message(
686                                 contents, destination, reply_path, format_args!("when sending CustomMessage")
687                         );
688                 }
689
690                 let mut pending_msgs = self.pending_messages.lock().unwrap();
691                 if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
692                         return msgs.pop_front()
693                 }
694                 None
695         }
696 }
697
698 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
699 // produces
700 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
701 /// [`SimpleArcPeerManager`]. See their docs for more details.
702 ///
703 /// This is not exported to bindings users as `Arc`s don't make sense in bindings.
704 ///
705 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
706 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
707 pub type SimpleArcOnionMessenger<L> = OnionMessenger<
708         Arc<KeysManager>,
709         Arc<KeysManager>,
710         Arc<L>,
711         Arc<DefaultMessageRouter>,
712         IgnoringMessageHandler,
713         IgnoringMessageHandler
714 >;
715
716 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
717 /// [`SimpleRefPeerManager`]. See their docs for more details.
718 ///
719 /// This is not exported to bindings users as general type aliases don't make sense in bindings.
720 ///
721 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
722 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
723 pub type SimpleRefOnionMessenger<'a, 'b, 'c, L> = OnionMessenger<
724         &'a KeysManager,
725         &'a KeysManager,
726         &'b L,
727         &'c DefaultMessageRouter,
728         IgnoringMessageHandler,
729         IgnoringMessageHandler
730 >;
731
732 /// Construct onion packet payloads and keys for sending an onion message along the given
733 /// `unblinded_path` to the given `destination`.
734 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
735         secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
736         mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
737 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
738         let num_hops = unblinded_path.len() + destination.num_hops();
739         let mut payloads = Vec::with_capacity(num_hops);
740         let mut onion_packet_keys = Vec::with_capacity(num_hops);
741
742         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath {
743                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
744                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
745         let num_unblinded_hops = num_hops - num_blinded_hops;
746
747         let mut unblinded_path_idx = 0;
748         let mut blinded_path_idx = 0;
749         let mut prev_control_tlvs_ss = None;
750         let mut final_control_tlvs = None;
751         utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
752                 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
753                         if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
754                                 if let Some(ss) = prev_control_tlvs_ss.take() {
755                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
756                                                 ForwardTlvs {
757                                                         next_node_id: unblinded_pk_opt.unwrap(),
758                                                         next_blinding_override: None,
759                                                 }
760                                         )), ss));
761                                 }
762                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
763                                 unblinded_path_idx += 1;
764                         } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
765                                 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
766                                         payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
767                                                 next_node_id: intro_node_id,
768                                                 next_blinding_override: Some(blinding_pt),
769                                         })), control_tlvs_ss));
770                                 }
771                         }
772                         if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
773                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
774                                         control_tlvs_ss));
775                                 blinded_path_idx += 1;
776                         } else if let Some(encrypted_payload) = enc_payload_opt {
777                                 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
778                                 prev_control_tlvs_ss = Some(control_tlvs_ss);
779                         }
780
781                         let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
782                         onion_packet_keys.push(onion_utils::OnionKeys {
783                                 #[cfg(test)]
784                                 shared_secret: onion_packet_ss,
785                                 #[cfg(test)]
786                                 blinding_factor: [0; 32],
787                                 ephemeral_pubkey,
788                                 rho,
789                                 mu,
790                         });
791                 }
792         )?;
793
794         if let Some(control_tlvs) = final_control_tlvs {
795                 payloads.push((Payload::Receive {
796                         control_tlvs,
797                         reply_path: reply_path.take(),
798                         message,
799                 }, prev_control_tlvs_ss.unwrap()));
800         } else {
801                 payloads.push((Payload::Receive {
802                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
803                         reply_path: reply_path.take(),
804                         message,
805                 }, prev_control_tlvs_ss.unwrap()));
806         }
807
808         Ok((payloads, onion_packet_keys))
809 }
810
811 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
812 fn construct_onion_message_packet<T: OnionMessageContents>(payloads: Vec<(Payload<T>, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
813         // Spec rationale:
814         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
815         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
816         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
817         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
818         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
819                 SMALL_PACKET_HOP_DATA_LEN
820         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
821                 BIG_PACKET_HOP_DATA_LEN
822         } else { return Err(()) };
823
824         onion_utils::construct_onion_message_packet::<_, _>(
825                 payloads, onion_keys, prng_seed, hop_data_len)
826 }