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 this [`OnionMessenger`], which lives here,
11 //! as well as various types, traits, and utilities that it uses.
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, IntroductionNode, NextMessageHop, NodeIdLookUp};
19 use crate::blinded_path::message::{advance_path_by_one, ForwardNode, ForwardTlvs, ReceiveTlvs};
20 use crate::blinded_path::utils;
21 use crate::events::{Event, EventHandler, EventsProvider};
22 use crate::sign::{EntropySource, NodeSigner, Recipient};
23 use crate::ln::features::{InitFeatures, NodeFeatures};
24 use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler, SocketAddress};
25 use crate::ln::onion_utils;
26 use crate::routing::gossip::{NetworkGraph, NodeId, ReadOnlyNetworkGraph};
27 use super::packet::OnionMessageContents;
28 use super::packet::ParsedOnionMessageContents;
29 use super::offers::OffersMessageHandler;
30 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
31 use crate::util::logger::{Logger, WithContext};
32 use crate::util::ser::Writeable;
37 use crate::sync::Mutex;
38 use crate::prelude::*;
40 #[cfg(not(c_bindings))]
42 crate::sign::KeysManager,
43 crate::ln::channelmanager::{SimpleArcChannelManager, SimpleRefChannelManager},
44 crate::ln::peer_handler::IgnoringMessageHandler,
48 pub(super) const MAX_TIMER_TICKS: usize = 2;
50 /// A trivial trait which describes any [`OnionMessenger`].
52 /// This is not exported to bindings users as general cover traits aren't useful in other
54 pub trait AOnionMessenger {
55 /// A type implementing [`EntropySource`]
56 type EntropySource: EntropySource + ?Sized;
57 /// A type that may be dereferenced to [`Self::EntropySource`]
58 type ES: Deref<Target = Self::EntropySource>;
59 /// A type implementing [`NodeSigner`]
60 type NodeSigner: NodeSigner + ?Sized;
61 /// A type that may be dereferenced to [`Self::NodeSigner`]
62 type NS: Deref<Target = Self::NodeSigner>;
63 /// A type implementing [`Logger`]
64 type Logger: Logger + ?Sized;
65 /// A type that may be dereferenced to [`Self::Logger`]
66 type L: Deref<Target = Self::Logger>;
67 /// A type implementing [`NodeIdLookUp`]
68 type NodeIdLookUp: NodeIdLookUp + ?Sized;
69 /// A type that may be dereferenced to [`Self::NodeIdLookUp`]
70 type NL: Deref<Target = Self::NodeIdLookUp>;
71 /// A type implementing [`MessageRouter`]
72 type MessageRouter: MessageRouter + ?Sized;
73 /// A type that may be dereferenced to [`Self::MessageRouter`]
74 type MR: Deref<Target = Self::MessageRouter>;
75 /// A type implementing [`OffersMessageHandler`]
76 type OffersMessageHandler: OffersMessageHandler + ?Sized;
77 /// A type that may be dereferenced to [`Self::OffersMessageHandler`]
78 type OMH: Deref<Target = Self::OffersMessageHandler>;
79 /// A type implementing [`CustomOnionMessageHandler`]
80 type CustomOnionMessageHandler: CustomOnionMessageHandler + ?Sized;
81 /// A type that may be dereferenced to [`Self::CustomOnionMessageHandler`]
82 type CMH: Deref<Target = Self::CustomOnionMessageHandler>;
83 /// Returns a reference to the actual [`OnionMessenger`] object.
84 fn get_om(&self) -> &OnionMessenger<Self::ES, Self::NS, Self::L, Self::NL, Self::MR, Self::OMH, Self::CMH>;
87 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> AOnionMessenger
88 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH> where
89 ES::Target: EntropySource,
90 NS::Target: NodeSigner,
92 NL::Target: NodeIdLookUp,
93 MR::Target: MessageRouter,
94 OMH::Target: OffersMessageHandler,
95 CMH::Target: CustomOnionMessageHandler,
97 type EntropySource = ES::Target;
99 type NodeSigner = NS::Target;
101 type Logger = L::Target;
103 type NodeIdLookUp = NL::Target;
105 type MessageRouter = MR::Target;
107 type OffersMessageHandler = OMH::Target;
109 type CustomOnionMessageHandler = CMH::Target;
111 fn get_om(&self) -> &OnionMessenger<ES, NS, L, NL, MR, OMH, CMH> { self }
114 /// A sender, receiver and forwarder of [`OnionMessage`]s.
116 /// # Handling Messages
118 /// `OnionMessenger` implements [`OnionMessageHandler`], making it responsible for either forwarding
119 /// messages to peers or delegating to the appropriate handler for the message type. Currently, the
120 /// available handlers are:
121 /// * [`OffersMessageHandler`], for responding to [`InvoiceRequest`]s and paying [`Bolt12Invoice`]s
122 /// * [`CustomOnionMessageHandler`], for handling user-defined message types
124 /// # Sending Messages
126 /// [`OnionMessage`]s are sent initially using [`OnionMessenger::send_onion_message`]. When handling
127 /// a message, the matched handler may return a response message which `OnionMessenger` will send
133 /// # extern crate bitcoin;
134 /// # use bitcoin::hashes::_export::_core::time::Duration;
135 /// # use bitcoin::hashes::hex::FromHex;
136 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey, self};
137 /// # use lightning::blinded_path::{BlindedPath, EmptyNodeIdLookUp};
138 /// # use lightning::blinded_path::message::ForwardNode;
139 /// # use lightning::sign::{EntropySource, KeysManager};
140 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
141 /// # use lightning::onion_message::messenger::{Destination, MessageRouter, OnionMessagePath, OnionMessenger};
142 /// # use lightning::onion_message::packet::OnionMessageContents;
143 /// # use lightning::util::logger::{Logger, Record};
144 /// # use lightning::util::ser::{Writeable, Writer};
145 /// # use lightning::io;
146 /// # use std::sync::Arc;
147 /// # struct FakeLogger;
148 /// # impl Logger for FakeLogger {
149 /// # fn log(&self, record: Record) { println!("{:?}" , record); }
151 /// # struct FakeMessageRouter {}
152 /// # impl MessageRouter for FakeMessageRouter {
153 /// # fn find_path(&self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination) -> Result<OnionMessagePath, ()> {
154 /// # let secp_ctx = Secp256k1::new();
155 /// # let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
156 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
157 /// # let hop_node_id2 = hop_node_id1;
158 /// # Ok(OnionMessagePath {
159 /// # intermediate_nodes: vec![hop_node_id1, hop_node_id2],
161 /// # first_node_addresses: None,
164 /// # fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
165 /// # &self, _recipient: PublicKey, _peers: Vec<PublicKey>, _secp_ctx: &Secp256k1<T>
166 /// # ) -> Result<Vec<BlindedPath>, ()> {
170 /// # let seed = [42u8; 32];
171 /// # let time = Duration::from_secs(123456);
172 /// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos());
173 /// # let logger = Arc::new(FakeLogger {});
174 /// # let node_secret = SecretKey::from_slice(&<Vec<u8>>::from_hex("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
175 /// # let secp_ctx = Secp256k1::new();
176 /// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret);
177 /// # let (hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1);
178 /// # let destination_node_id = hop_node_id1;
179 /// # let node_id_lookup = EmptyNodeIdLookUp {};
180 /// # let message_router = Arc::new(FakeMessageRouter {});
181 /// # let custom_message_handler = IgnoringMessageHandler {};
182 /// # let offers_message_handler = IgnoringMessageHandler {};
183 /// // Create the onion messenger. This must use the same `keys_manager` as is passed to your
184 /// // ChannelManager.
185 /// let onion_messenger = OnionMessenger::new(
186 /// &keys_manager, &keys_manager, logger, &node_id_lookup, message_router,
187 /// &offers_message_handler, &custom_message_handler
190 /// # #[derive(Debug)]
191 /// # struct YourCustomMessage {}
192 /// impl Writeable for YourCustomMessage {
193 /// fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
195 /// // Write your custom onion message to `w`
198 /// impl OnionMessageContents for YourCustomMessage {
199 /// fn tlv_type(&self) -> u64 {
200 /// # let your_custom_message_type = 42;
201 /// your_custom_message_type
203 /// fn msg_type(&self) -> &'static str { "YourCustomMessageType" }
205 /// // Send a custom onion message to a node id.
206 /// let destination = Destination::Node(destination_node_id);
207 /// let reply_path = None;
208 /// # let message = YourCustomMessage {};
209 /// onion_messenger.send_onion_message(message, destination, reply_path);
211 /// // Create a blinded path to yourself, for someone to send an onion message to.
212 /// # let your_node_id = hop_node_id1;
214 /// ForwardNode { node_id: hop_node_id3, short_channel_id: None },
215 /// ForwardNode { node_id: hop_node_id4, short_channel_id: None },
217 /// let blinded_path = BlindedPath::new_for_message(&hops, your_node_id, &keys_manager, &secp_ctx).unwrap();
219 /// // Send a custom onion message to a blinded path.
220 /// let destination = Destination::BlindedPath(blinded_path);
221 /// let reply_path = None;
222 /// # let message = YourCustomMessage {};
223 /// onion_messenger.send_onion_message(message, destination, reply_path);
226 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
227 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
228 pub struct OnionMessenger<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref>
230 ES::Target: EntropySource,
231 NS::Target: NodeSigner,
233 NL::Target: NodeIdLookUp,
234 MR::Target: MessageRouter,
235 OMH::Target: OffersMessageHandler,
236 CMH::Target: CustomOnionMessageHandler,
241 message_recipients: Mutex<HashMap<PublicKey, OnionMessageRecipient>>,
242 secp_ctx: Secp256k1<secp256k1::All>,
247 intercept_messages_for_offline_peers: bool,
248 pending_events: Mutex<PendingEvents>,
251 struct PendingEvents {
252 intercepted_msgs: Vec<Event>,
253 peer_connecteds: Vec<Event>,
256 /// [`OnionMessage`]s buffered to be sent.
257 enum OnionMessageRecipient {
258 /// Messages for a node connected as a peer.
259 ConnectedPeer(VecDeque<OnionMessage>),
261 /// Messages for a node that is not yet connected, which are dropped after [`MAX_TIMER_TICKS`]
262 /// and tracked here.
263 PendingConnection(VecDeque<OnionMessage>, Option<Vec<SocketAddress>>, usize),
266 impl OnionMessageRecipient {
267 fn pending_connection(addresses: Vec<SocketAddress>) -> Self {
268 Self::PendingConnection(VecDeque::new(), Some(addresses), 0)
271 fn pending_messages(&self) -> &VecDeque<OnionMessage> {
273 OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
274 OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
278 fn enqueue_message(&mut self, message: OnionMessage) {
279 let pending_messages = match self {
280 OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
281 OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
284 pending_messages.push_back(message);
287 fn dequeue_message(&mut self) -> Option<OnionMessage> {
288 let pending_messages = match self {
289 OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
290 OnionMessageRecipient::PendingConnection(pending_messages, _, _) => {
291 debug_assert!(false);
296 pending_messages.pop_front()
300 fn release_pending_messages(&mut self) -> VecDeque<OnionMessage> {
301 let pending_messages = match self {
302 OnionMessageRecipient::ConnectedPeer(pending_messages) => pending_messages,
303 OnionMessageRecipient::PendingConnection(pending_messages, _, _) => pending_messages,
306 core::mem::take(pending_messages)
309 fn mark_connected(&mut self) {
310 if let OnionMessageRecipient::PendingConnection(pending_messages, _, _) = self {
311 let mut new_pending_messages = VecDeque::new();
312 core::mem::swap(pending_messages, &mut new_pending_messages);
313 *self = OnionMessageRecipient::ConnectedPeer(new_pending_messages);
317 fn is_connected(&self) -> bool {
319 OnionMessageRecipient::ConnectedPeer(..) => true,
320 OnionMessageRecipient::PendingConnection(..) => false,
326 /// The `Responder` struct creates an appropriate [`ResponseInstruction`]
327 /// for responding to a message.
328 #[derive(Clone, Debug, Eq, PartialEq)]
329 pub struct Responder {
330 /// The path along which a response can be sent.
331 reply_path: BlindedPath,
332 path_id: Option<[u8; 32]>
335 impl_writeable_tlv_based!(Responder, {
336 (0, reply_path, required),
337 (2, path_id, option),
341 /// Creates a new [`Responder`] instance with the provided reply path.
342 pub(super) fn new(reply_path: BlindedPath, path_id: Option<[u8; 32]>) -> Self {
349 /// Creates a [`ResponseInstruction::WithoutReplyPath`] for a given response.
351 /// Use when the recipient doesn't need to send back a reply to us.
352 pub fn respond<T: OnionMessageContents>(self, response: T) -> ResponseInstruction<T> {
353 ResponseInstruction::WithoutReplyPath(OnionMessageResponse {
355 reply_path: self.reply_path,
356 path_id: self.path_id,
360 /// Creates a [`ResponseInstruction::WithReplyPath`] for a given response.
362 /// Use when the recipient needs to send back a reply to us.
363 pub fn respond_with_reply_path<T: OnionMessageContents>(self, response: T) -> ResponseInstruction<T> {
364 ResponseInstruction::WithReplyPath(OnionMessageResponse {
366 reply_path: self.reply_path,
367 path_id: self.path_id,
372 /// This struct contains the information needed to reply to a received message.
373 pub struct OnionMessageResponse<T: OnionMessageContents> {
375 reply_path: BlindedPath,
376 path_id: Option<[u8; 32]>,
379 /// `ResponseInstruction` represents instructions for responding to received messages.
380 pub enum ResponseInstruction<T: OnionMessageContents> {
381 /// Indicates that a response should be sent including a reply path for
382 /// the recipient to respond back.
383 WithReplyPath(OnionMessageResponse<T>),
384 /// Indicates that a response should be sent without including a reply path
385 /// for the recipient to respond back.
386 WithoutReplyPath(OnionMessageResponse<T>),
387 /// Indicates that there's no response to send back.
391 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
393 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
394 /// enqueued for sending.
395 #[cfg(not(c_bindings))]
396 pub struct PendingOnionMessage<T: OnionMessageContents> {
397 /// The message contents to send in an [`OnionMessage`].
400 /// The destination of the message.
401 pub destination: Destination,
403 /// A reply path to include in the [`OnionMessage`] for a response.
404 pub reply_path: Option<BlindedPath>,
408 /// An [`OnionMessage`] for [`OnionMessenger`] to send.
410 /// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
411 /// enqueued for sending.
412 pub type PendingOnionMessage<T> = (T, Destination, Option<BlindedPath>);
414 pub(crate) fn new_pending_onion_message<T: OnionMessageContents>(
415 contents: T, destination: Destination, reply_path: Option<BlindedPath>
416 ) -> PendingOnionMessage<T> {
417 #[cfg(not(c_bindings))]
418 return PendingOnionMessage { contents, destination, reply_path };
420 return (contents, destination, reply_path);
423 /// A trait defining behavior for routing an [`OnionMessage`].
424 pub trait MessageRouter {
425 /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
427 &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
428 ) -> Result<OnionMessagePath, ()>;
430 /// Creates [`BlindedPath`]s to the `recipient` node. The nodes in `peers` are assumed to be
431 /// direct peers with the `recipient`.
432 fn create_blinded_paths<
433 T: secp256k1::Signing + secp256k1::Verification
435 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
436 ) -> Result<Vec<BlindedPath>, ()>;
438 /// Creates compact [`BlindedPath`]s to the `recipient` node. The nodes in `peers` are assumed
439 /// to be direct peers with the `recipient`.
441 /// Compact blinded paths use short channel ids instead of pubkeys for a smaller serialization,
442 /// which is beneficial when a QR code is used to transport the data. The SCID is passed using a
443 /// [`ForwardNode`] but may be `None` for graceful degradation.
445 /// Implementations using additional intermediate nodes are responsible for using a
446 /// [`ForwardNode`] with `Some` short channel id, if possible. Similarly, implementations should
447 /// call [`BlindedPath::use_compact_introduction_node`].
449 /// The provided implementation simply delegates to [`MessageRouter::create_blinded_paths`],
450 /// ignoring the short channel ids.
451 fn create_compact_blinded_paths<
452 T: secp256k1::Signing + secp256k1::Verification
454 &self, recipient: PublicKey, peers: Vec<ForwardNode>, secp_ctx: &Secp256k1<T>,
455 ) -> Result<Vec<BlindedPath>, ()> {
458 .map(|ForwardNode { node_id, short_channel_id: _ }| node_id)
460 self.create_blinded_paths(recipient, peers, secp_ctx)
464 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
468 /// Creating [`BlindedPath`]s may affect privacy since, if a suitable path cannot be found, it will
469 /// create a one-hop path using the recipient as the introduction node if it is a announced node.
470 /// Otherwise, there is no way to find a path to the introduction node in order to send a message,
471 /// and thus an `Err` is returned.
472 pub struct DefaultMessageRouter<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref>
475 ES::Target: EntropySource,
481 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> DefaultMessageRouter<G, L, ES>
484 ES::Target: EntropySource,
486 /// Creates a [`DefaultMessageRouter`] using the given [`NetworkGraph`].
487 pub fn new(network_graph: G, entropy_source: ES) -> Self {
488 Self { network_graph, entropy_source }
491 fn create_blinded_paths_from_iter<
492 I: ExactSizeIterator<Item = ForwardNode>,
493 T: secp256k1::Signing + secp256k1::Verification
495 &self, recipient: PublicKey, peers: I, secp_ctx: &Secp256k1<T>, compact_paths: bool
496 ) -> Result<Vec<BlindedPath>, ()> {
497 // Limit the number of blinded paths that are computed.
498 const MAX_PATHS: usize = 3;
500 // Ensure peers have at least three channels so that it is more difficult to infer the
501 // recipient's node_id.
502 const MIN_PEER_CHANNELS: usize = 3;
504 let network_graph = self.network_graph.deref().read_only();
505 let is_recipient_announced =
506 network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient));
508 let has_one_peer = peers.len() == 1;
509 let mut peer_info = peers
510 // Limit to peers with announced channels unless the recipient is unannounced.
513 .node(&NodeId::from_pubkey(&peer.node_id))
514 .filter(|info| info.channels.len() >= MIN_PEER_CHANNELS)
515 .map(|info| (peer, info.is_tor_only(), info.channels.len()))
516 // Allow messages directly with the only peer when unannounced.
517 .or_else(|| (!is_recipient_announced && has_one_peer)
518 .then(|| (peer, false, 0))
521 // Exclude Tor-only nodes when the recipient is announced.
522 .filter(|(_, is_tor_only, _)| !(*is_tor_only && is_recipient_announced))
523 .collect::<Vec<_>>();
525 // Prefer using non-Tor nodes with the most channels as the introduction node.
526 peer_info.sort_unstable_by(|(_, a_tor_only, a_channels), (_, b_tor_only, b_channels)| {
527 a_tor_only.cmp(b_tor_only).then(a_channels.cmp(b_channels).reverse())
530 let paths = peer_info.into_iter()
531 .map(|(peer, _, _)| {
532 BlindedPath::new_for_message(&[peer], recipient, &*self.entropy_source, secp_ctx)
535 .collect::<Result<Vec<_>, _>>();
537 let mut paths = match paths {
538 Ok(paths) if !paths.is_empty() => Ok(paths),
540 if is_recipient_announced {
541 BlindedPath::one_hop_for_message(recipient, &*self.entropy_source, secp_ctx)
542 .map(|path| vec![path])
550 for path in &mut paths {
551 path.use_compact_introduction_node(&network_graph);
559 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> MessageRouter for DefaultMessageRouter<G, L, ES>
562 ES::Target: EntropySource,
565 &self, sender: PublicKey, peers: Vec<PublicKey>, mut destination: Destination
566 ) -> Result<OnionMessagePath, ()> {
567 let network_graph = self.network_graph.deref().read_only();
568 destination.resolve(&network_graph);
570 let first_node = match destination.first_node() {
571 Some(first_node) => first_node,
572 None => return Err(()),
575 if peers.contains(&first_node) || sender == first_node {
576 Ok(OnionMessagePath {
577 intermediate_nodes: vec![], destination, first_node_addresses: None
580 let node_details = network_graph
581 .node(&NodeId::from_pubkey(&first_node))
582 .and_then(|node_info| node_info.announcement_info.as_ref())
583 .map(|announcement_info| (announcement_info.features(), announcement_info.addresses()));
586 Some((features, addresses)) if features.supports_onion_messages() && addresses.len() > 0 => {
587 let first_node_addresses = Some(addresses.clone());
588 Ok(OnionMessagePath {
589 intermediate_nodes: vec![], destination, first_node_addresses
597 fn create_blinded_paths<
598 T: secp256k1::Signing + secp256k1::Verification
600 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
601 ) -> Result<Vec<BlindedPath>, ()> {
604 .map(|node_id| ForwardNode { node_id, short_channel_id: None });
605 self.create_blinded_paths_from_iter(recipient, peers, secp_ctx, false)
608 fn create_compact_blinded_paths<
609 T: secp256k1::Signing + secp256k1::Verification
611 &self, recipient: PublicKey, peers: Vec<ForwardNode>, secp_ctx: &Secp256k1<T>,
612 ) -> Result<Vec<BlindedPath>, ()> {
613 self.create_blinded_paths_from_iter(recipient, peers.into_iter(), secp_ctx, true)
617 /// A path for sending an [`OnionMessage`].
619 pub struct OnionMessagePath {
620 /// Nodes on the path between the sender and the destination.
621 pub intermediate_nodes: Vec<PublicKey>,
623 /// The recipient of the message.
624 pub destination: Destination,
626 /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
628 /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
629 /// this to initiate such a connection.
630 pub first_node_addresses: Option<Vec<SocketAddress>>,
633 impl OnionMessagePath {
634 /// Returns the first node in the path.
635 pub fn first_node(&self) -> Option<PublicKey> {
636 self.intermediate_nodes
639 .or_else(|| self.destination.first_node())
643 /// The destination of an onion message.
644 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
645 pub enum Destination {
646 /// We're sending this onion message to a node.
648 /// We're sending this onion message to a blinded path.
649 BlindedPath(BlindedPath),
653 /// Attempts to resolve the [`IntroductionNode::DirectedShortChannelId`] of a
654 /// [`Destination::BlindedPath`] to a [`IntroductionNode::NodeId`], if applicable, using the
655 /// provided [`ReadOnlyNetworkGraph`].
656 pub fn resolve(&mut self, network_graph: &ReadOnlyNetworkGraph) {
657 if let Destination::BlindedPath(path) = self {
658 if let IntroductionNode::DirectedShortChannelId(..) = path.introduction_node {
659 if let Some(pubkey) = path
660 .public_introduction_node_id(network_graph)
661 .and_then(|node_id| node_id.as_pubkey().ok())
663 path.introduction_node = IntroductionNode::NodeId(pubkey);
669 pub(super) fn num_hops(&self) -> usize {
671 Destination::Node(_) => 1,
672 Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
676 fn first_node(&self) -> Option<PublicKey> {
678 Destination::Node(node_id) => Some(*node_id),
679 Destination::BlindedPath(BlindedPath { introduction_node, .. }) => {
680 match introduction_node {
681 IntroductionNode::NodeId(pubkey) => Some(*pubkey),
682 IntroductionNode::DirectedShortChannelId(..) => None,
689 /// Result of successfully [sending an onion message].
691 /// [sending an onion message]: OnionMessenger::send_onion_message
692 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
693 pub enum SendSuccess {
694 /// The message was buffered and will be sent once it is processed by
695 /// [`OnionMessageHandler::next_onion_message_for_peer`].
697 /// The message was buffered and will be sent once the node is connected as a peer and it is
698 /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
699 BufferedAwaitingConnection(PublicKey),
702 /// Errors that may occur when [sending an onion message].
704 /// [sending an onion message]: OnionMessenger::send_onion_message
705 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
707 /// Errored computing onion message packet keys.
708 Secp256k1(secp256k1::Error),
709 /// Because implementations such as Eclair will drop onion messages where the message packet
710 /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
712 /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
715 /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
716 InvalidFirstHop(PublicKey),
717 /// Indicates that a path could not be found by the [`MessageRouter`].
719 /// This occurs when either:
720 /// - No path from the sender to the destination was found to send the onion message
721 /// - No reply path to the sender could be created when responding to an onion message
723 /// Onion message contents must have a TLV type >= 64.
725 /// Our next-hop peer's buffer was full or our total outbound buffer was full.
727 /// Failed to retrieve our node id from the provided [`NodeSigner`].
729 /// [`NodeSigner`]: crate::sign::NodeSigner
731 /// The provided [`Destination`] has a blinded path with an unresolved introduction node. An
732 /// attempt to resolve it in the [`MessageRouter`] when finding an [`OnionMessagePath`] likely
734 UnresolvedIntroductionNode,
735 /// We attempted to send to a blinded path where we are the introduction node, and failed to
736 /// advance the blinded path to make the second hop the new introduction node. Either
737 /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
738 /// new blinding point, or we were attempting to send to ourselves.
739 BlindedPathAdvanceFailed,
742 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
743 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
744 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
745 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
748 /// See [`OnionMessenger`] for example usage.
750 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
751 /// [`CustomMessage`]: Self::CustomMessage
752 pub trait CustomOnionMessageHandler {
753 /// The message known to the handler. To support multiple message types, you may want to make this
754 /// an enum with a variant for each supported message.
755 type CustomMessage: OnionMessageContents;
757 /// Called with the custom message that was received, returning a response to send, if any.
759 /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
760 fn handle_custom_message(&self, message: Self::CustomMessage, responder: Option<Responder>) -> ResponseInstruction<Self::CustomMessage>;
762 /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
763 /// message type is unknown.
764 fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
766 /// Releases any [`Self::CustomMessage`]s that need to be sent.
768 /// Typically, this is used for messages initiating a message flow rather than in response to
769 /// another message. The latter should use the return value of [`Self::handle_custom_message`].
770 #[cfg(not(c_bindings))]
771 fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
773 /// Releases any [`Self::CustomMessage`]s that need to be sent.
775 /// Typically, this is used for messages initiating a message flow rather than in response to
776 /// another message. The latter should use the return value of [`Self::handle_custom_message`].
778 fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
781 /// A processed incoming onion message, containing either a Forward (another onion message)
782 /// or a Receive payload with decrypted contents.
783 #[derive(Clone, Debug)]
784 pub enum PeeledOnion<T: OnionMessageContents> {
785 /// Forwarded onion, with the next node id and a new onion
786 Forward(NextMessageHop, OnionMessage),
787 /// Received onion message, with decrypted contents, path_id, and reply path
788 Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
792 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
793 /// `path`, first calling [`Destination::resolve`] on `path.destination` with the given
794 /// [`ReadOnlyNetworkGraph`].
796 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
797 /// needed to connect to the first node.
798 pub fn create_onion_message_resolving_destination<
799 ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents
801 entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
802 network_graph: &ReadOnlyNetworkGraph, secp_ctx: &Secp256k1<secp256k1::All>,
803 mut path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
804 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
806 ES::Target: EntropySource,
807 NS::Target: NodeSigner,
808 NL::Target: NodeIdLookUp,
810 path.destination.resolve(network_graph);
811 create_onion_message(
812 entropy_source, node_signer, node_id_lookup, secp_ctx, path, contents, reply_path,
816 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
819 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
820 /// needed to connect to the first node.
822 /// Returns [`SendError::UnresolvedIntroductionNode`] if:
823 /// - `destination` contains a blinded path with an [`IntroductionNode::DirectedShortChannelId`],
824 /// - unless it can be resolved by [`NodeIdLookUp::next_node_id`].
825 /// Use [`create_onion_message_resolving_destination`] instead to resolve the introduction node
826 /// first with a [`ReadOnlyNetworkGraph`].
827 pub fn create_onion_message<ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents>(
828 entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
829 secp_ctx: &Secp256k1<secp256k1::All>, path: OnionMessagePath, contents: T,
830 reply_path: Option<BlindedPath>,
831 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
833 ES::Target: EntropySource,
834 NS::Target: NodeSigner,
835 NL::Target: NodeIdLookUp,
837 let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
838 if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
839 if blinded_hops.is_empty() {
840 return Err(SendError::TooFewBlindedHops);
844 if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
846 // If we are sending straight to a blinded path and we are the introduction node, we need to
847 // advance the blinded path by 1 hop so the second hop is the new introduction node.
848 if intermediate_nodes.len() == 0 {
849 if let Destination::BlindedPath(ref mut blinded_path) = destination {
850 let our_node_id = node_signer.get_node_id(Recipient::Node)
851 .map_err(|()| SendError::GetNodeIdFailed)?;
852 let introduction_node_id = match blinded_path.introduction_node {
853 IntroductionNode::NodeId(pubkey) => pubkey,
854 IntroductionNode::DirectedShortChannelId(direction, scid) => {
855 match node_id_lookup.next_node_id(scid) {
856 Some(next_node_id) => *direction.select_pubkey(&our_node_id, &next_node_id),
857 None => return Err(SendError::UnresolvedIntroductionNode),
861 if introduction_node_id == our_node_id {
862 advance_path_by_one(blinded_path, node_signer, node_id_lookup, &secp_ctx)
863 .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
868 let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
869 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
870 let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
871 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
874 Destination::Node(pk) => (*pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
875 Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, .. }) => {
876 match introduction_node {
877 IntroductionNode::NodeId(pubkey) => (*pubkey, *blinding_point),
878 IntroductionNode::DirectedShortChannelId(..) => {
879 return Err(SendError::UnresolvedIntroductionNode);
885 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
886 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret
889 let prng_seed = entropy_source.get_secure_random_bytes();
890 let onion_routing_packet = construct_onion_message_packet(
891 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
893 let message = OnionMessage { blinding_point, onion_routing_packet };
894 Ok((first_node_id, message, first_node_addresses))
897 /// Decode one layer of an incoming [`OnionMessage`].
899 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
901 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
902 msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
904 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
906 NS::Target: NodeSigner,
908 CMH::Target: CustomOnionMessageHandler,
910 let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
913 log_error!(logger, "Failed to retrieve node secret: {:?}", e);
917 let onion_decode_ss = {
918 let blinding_factor = {
919 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
920 hmac.input(control_tlvs_ss.as_ref());
921 Hmac::from_engine(hmac).to_byte_array()
923 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
924 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
926 Ok(ss) => ss.secret_bytes(),
928 log_trace!(logger, "Failed to compute onion packet shared secret");
933 match onion_utils::decode_next_untagged_hop(
934 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
935 (control_tlvs_ss, custom_handler.deref(), logger.deref())
937 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
938 message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
940 Ok(PeeledOnion::Receive(message, path_id, reply_path))
942 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
943 next_hop, next_blinding_override
944 })), Some((next_hop_hmac, new_packet_bytes)))) => {
945 // TODO: we need to check whether `next_hop` is our node, in which case this is a dummy
946 // blinded hop and this onion message is destined for us. In this situation, we should keep
947 // unwrapping the onion layers to get to the final payload. Since we don't have the option
948 // of creating blinded paths with dummy hops currently, we should be ok to not handle this
950 let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
953 log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
957 let outgoing_packet = Packet {
959 public_key: new_pubkey,
960 hop_data: new_packet_bytes,
963 let onion_message = OnionMessage {
964 blinding_point: match next_blinding_override {
965 Some(blinding_point) => blinding_point,
967 match onion_utils::next_hop_pubkey(
968 &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
972 log_trace!(logger, "Failed to compute next blinding point: {}", e);
978 onion_routing_packet: outgoing_packet,
981 Ok(PeeledOnion::Forward(next_hop, onion_message))
984 log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
988 log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
994 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref>
995 OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
997 ES::Target: EntropySource,
998 NS::Target: NodeSigner,
1000 NL::Target: NodeIdLookUp,
1001 MR::Target: MessageRouter,
1002 OMH::Target: OffersMessageHandler,
1003 CMH::Target: CustomOnionMessageHandler,
1005 /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
1006 /// their respective handlers.
1008 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL, message_router: MR,
1009 offers_handler: OMH, custom_handler: CMH
1012 entropy_source, node_signer, logger, node_id_lookup, message_router,
1013 offers_handler, custom_handler, false
1017 /// Similar to [`Self::new`], but rather than dropping onion messages that are
1018 /// intended to be forwarded to offline peers, we will intercept them for
1019 /// later forwarding.
1021 /// Interception flow:
1022 /// 1. If an onion message for an offline peer is received, `OnionMessenger` will
1023 /// generate an [`Event::OnionMessageIntercepted`]. Event handlers can
1024 /// then choose to persist this onion message for later forwarding, or drop
1026 /// 2. When the offline peer later comes back online, `OnionMessenger` will
1027 /// generate an [`Event::OnionMessagePeerConnected`]. Event handlers will
1028 /// then fetch all previously intercepted onion messages for this peer.
1029 /// 3. Once the stored onion messages are fetched, they can finally be
1030 /// forwarded to the now-online peer via [`Self::forward_onion_message`].
1034 /// LDK will not rate limit how many [`Event::OnionMessageIntercepted`]s
1035 /// are generated, so it is the caller's responsibility to limit how many
1036 /// onion messages are persisted and only persist onion messages for relevant
1038 pub fn new_with_offline_peer_interception(
1039 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL,
1040 message_router: MR, offers_handler: OMH, custom_handler: CMH
1043 entropy_source, node_signer, logger, node_id_lookup, message_router,
1044 offers_handler, custom_handler, true
1049 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL,
1050 message_router: MR, offers_handler: OMH, custom_handler: CMH,
1051 intercept_messages_for_offline_peers: bool
1053 let mut secp_ctx = Secp256k1::new();
1054 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
1058 message_recipients: Mutex::new(new_hash_map()),
1065 intercept_messages_for_offline_peers,
1066 pending_events: Mutex::new(PendingEvents {
1067 intercepted_msgs: Vec::new(),
1068 peer_connecteds: Vec::new(),
1074 pub(crate) fn set_offers_handler(&mut self, offers_handler: OMH) {
1075 self.offers_handler = offers_handler;
1078 /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
1080 /// See [`OnionMessenger`] for example usage.
1081 pub fn send_onion_message<T: OnionMessageContents>(
1082 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
1083 ) -> Result<SendSuccess, SendError> {
1084 self.find_path_and_enqueue_onion_message(
1085 contents, destination, reply_path, format_args!("")
1089 fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
1090 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
1091 log_suffix: fmt::Arguments
1092 ) -> Result<SendSuccess, SendError> {
1093 let mut logger = WithContext::from(&self.logger, None, None, None);
1094 let result = self.find_path(destination).and_then(|path| {
1095 let first_hop = path.intermediate_nodes.get(0).map(|p| *p);
1096 logger = WithContext::from(&self.logger, first_hop, None, None);
1097 self.enqueue_onion_message(path, contents, reply_path, log_suffix)
1100 match result.as_ref() {
1101 Err(SendError::GetNodeIdFailed) => {
1102 log_warn!(logger, "Unable to retrieve node id {}", log_suffix);
1104 Err(SendError::PathNotFound) => {
1105 log_trace!(logger, "Failed to find path {}", log_suffix);
1108 log_trace!(logger, "Failed sending onion message {}: {:?}", log_suffix, e);
1110 Ok(SendSuccess::Buffered) => {
1111 log_trace!(logger, "Buffered onion message {}", log_suffix);
1113 Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
1116 "Buffered onion message waiting on peer connection {}: {}",
1125 fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
1126 let sender = self.node_signer
1127 .get_node_id(Recipient::Node)
1128 .map_err(|_| SendError::GetNodeIdFailed)?;
1130 let peers = self.message_recipients.lock().unwrap()
1132 .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
1133 .map(|(node_id, _)| *node_id)
1137 .find_path(sender, peers, destination)
1138 .map_err(|_| SendError::PathNotFound)
1141 fn create_blinded_path(&self) -> Result<BlindedPath, SendError> {
1142 let recipient = self.node_signer
1143 .get_node_id(Recipient::Node)
1144 .map_err(|_| SendError::GetNodeIdFailed)?;
1145 let secp_ctx = &self.secp_ctx;
1147 let peers = self.message_recipients.lock().unwrap()
1149 .filter(|(_, peer)| matches!(peer, OnionMessageRecipient::ConnectedPeer(_)))
1150 .map(|(node_id, _ )| *node_id)
1151 .collect::<Vec<_>>();
1154 .create_blinded_paths(recipient, peers, secp_ctx)
1155 .and_then(|paths| paths.into_iter().next().ok_or(()))
1156 .map_err(|_| SendError::PathNotFound)
1159 fn enqueue_onion_message<T: OnionMessageContents>(
1160 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
1161 log_suffix: fmt::Arguments
1162 ) -> Result<SendSuccess, SendError> {
1163 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
1165 let (first_node_id, onion_message, addresses) = create_onion_message(
1166 &self.entropy_source, &self.node_signer, &self.node_id_lookup, &self.secp_ctx, path,
1167 contents, reply_path,
1170 let mut message_recipients = self.message_recipients.lock().unwrap();
1171 if outbound_buffer_full(&first_node_id, &message_recipients) {
1172 return Err(SendError::BufferFull);
1175 match message_recipients.entry(first_node_id) {
1176 hash_map::Entry::Vacant(e) => match addresses {
1177 None => Err(SendError::InvalidFirstHop(first_node_id)),
1178 Some(addresses) => {
1179 e.insert(OnionMessageRecipient::pending_connection(addresses))
1180 .enqueue_message(onion_message);
1181 Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
1184 hash_map::Entry::Occupied(mut e) => {
1185 e.get_mut().enqueue_message(onion_message);
1186 if e.get().is_connected() {
1187 Ok(SendSuccess::Buffered)
1189 Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
1195 /// Forwards an [`OnionMessage`] to `peer_node_id`. Useful if we initialized
1196 /// the [`OnionMessenger`] with [`Self::new_with_offline_peer_interception`]
1197 /// and want to forward a previously intercepted onion message to a peer that
1198 /// has just come online.
1199 pub fn forward_onion_message(
1200 &self, message: OnionMessage, peer_node_id: &PublicKey
1201 ) -> Result<(), SendError> {
1202 let mut message_recipients = self.message_recipients.lock().unwrap();
1203 if outbound_buffer_full(&peer_node_id, &message_recipients) {
1204 return Err(SendError::BufferFull);
1207 match message_recipients.entry(*peer_node_id) {
1208 hash_map::Entry::Occupied(mut e) if e.get().is_connected() => {
1209 e.get_mut().enqueue_message(message);
1212 _ => Err(SendError::InvalidFirstHop(*peer_node_id))
1216 #[cfg(any(test, feature = "_test_utils"))]
1217 pub fn send_onion_message_using_path<T: OnionMessageContents>(
1218 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
1219 ) -> Result<SendSuccess, SendError> {
1220 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
1223 pub(crate) fn peel_onion_message(
1224 &self, msg: &OnionMessage
1225 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()> {
1227 msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
1231 /// Handles the response to an [`OnionMessage`] based on its [`ResponseInstruction`],
1232 /// enqueueing any response for sending.
1234 /// This function is useful for asynchronous handling of [`OnionMessage`]s.
1235 /// Handlers have the option to return [`ResponseInstruction::NoResponse`], indicating that
1236 /// no immediate response should be sent. Then, they can transfer the associated [`Responder`]
1237 /// to another task responsible for generating the response asynchronously. Subsequently, when
1238 /// the response is prepared and ready for sending, that task can invoke this method to enqueue
1239 /// the response for delivery.
1240 pub fn handle_onion_message_response<T: OnionMessageContents>(
1241 &self, response: ResponseInstruction<T>
1242 ) -> Result<Option<SendSuccess>, SendError> {
1243 let (response, create_reply_path) = match response {
1244 ResponseInstruction::WithReplyPath(response) => (response, true),
1245 ResponseInstruction::WithoutReplyPath(response) => (response, false),
1246 ResponseInstruction::NoResponse => return Ok(None),
1249 let message_type = response.message.msg_type();
1250 let reply_path = if create_reply_path {
1251 match self.create_blinded_path() {
1252 Ok(reply_path) => Some(reply_path),
1256 "Failed to create reply path when responding with {} to an onion message \
1257 with path_id {:02x?}: {:?}",
1258 message_type, response.path_id, err
1265 self.find_path_and_enqueue_onion_message(
1266 response.message, Destination::BlindedPath(response.reply_path), reply_path,
1268 "when responding with {} to an onion message with path_id {:02x?}",
1272 ).map(|result| Some(result))
1276 pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
1277 let mut message_recipients = self.message_recipients.lock().unwrap();
1278 let mut msgs = new_hash_map();
1279 // We don't want to disconnect the peers by removing them entirely from the original map, so we
1280 // release the pending message buffers individually.
1281 for (node_id, recipient) in &mut *message_recipients {
1282 msgs.insert(*node_id, recipient.release_pending_messages());
1287 fn enqueue_intercepted_event(&self, event: Event) {
1288 const MAX_EVENTS_BUFFER_SIZE: usize = (1 << 10) * 256;
1289 let mut pending_events = self.pending_events.lock().unwrap();
1290 let total_buffered_bytes: usize =
1291 pending_events.intercepted_msgs.iter().map(|ev| ev.serialized_length()).sum();
1292 if total_buffered_bytes >= MAX_EVENTS_BUFFER_SIZE {
1293 log_trace!(self.logger, "Dropping event {:?}: buffer full", event);
1296 pending_events.intercepted_msgs.push(event);
1299 /// Processes any events asynchronously using the given handler.
1301 /// Note that the event handler is called in the order each event was generated, however
1302 /// futures are polled in parallel for some events to allow for parallelism where events do not
1303 /// have an ordering requirement.
1305 /// See the trait-level documentation of [`EventsProvider`] for requirements.
1306 pub async fn process_pending_events_async<Future: core::future::Future<Output = ()> + core::marker::Unpin, H: Fn(Event) -> Future>(
1309 let mut intercepted_msgs = Vec::new();
1310 let mut peer_connecteds = Vec::new();
1312 let mut pending_events = self.pending_events.lock().unwrap();
1313 core::mem::swap(&mut pending_events.intercepted_msgs, &mut intercepted_msgs);
1314 core::mem::swap(&mut pending_events.peer_connecteds, &mut peer_connecteds);
1317 let mut futures = Vec::with_capacity(intercepted_msgs.len());
1318 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
1319 if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
1320 if let Some(addresses) = addresses.take() {
1321 futures.push(Some(handler(Event::ConnectionNeeded { node_id: *node_id, addresses })));
1326 for ev in intercepted_msgs {
1327 if let Event::OnionMessageIntercepted { .. } = ev {} else { debug_assert!(false); }
1328 futures.push(Some(handler(ev)));
1330 // Let the `OnionMessageIntercepted` events finish before moving on to peer_connecteds
1331 crate::util::async_poll::MultiFuturePoller(futures).await;
1333 if peer_connecteds.len() <= 1 {
1334 for event in peer_connecteds { handler(event).await; }
1336 let mut futures = Vec::new();
1337 for event in peer_connecteds {
1338 futures.push(Some(handler(event)));
1340 crate::util::async_poll::MultiFuturePoller(futures).await;
1345 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
1346 const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
1347 const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
1348 let mut total_buffered_bytes = 0;
1349 let mut peer_buffered_bytes = 0;
1350 for (pk, peer_buf) in buffer {
1351 for om in peer_buf.pending_messages() {
1352 let om_len = om.serialized_length();
1353 if pk == peer_node_id {
1354 peer_buffered_bytes += om_len;
1356 total_buffered_bytes += om_len;
1358 if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
1359 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
1368 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
1369 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
1371 ES::Target: EntropySource,
1372 NS::Target: NodeSigner,
1374 NL::Target: NodeIdLookUp,
1375 MR::Target: MessageRouter,
1376 OMH::Target: OffersMessageHandler,
1377 CMH::Target: CustomOnionMessageHandler,
1379 fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
1380 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
1381 if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
1382 if let Some(addresses) = addresses.take() {
1383 handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
1387 let mut events = Vec::new();
1389 let mut pending_events = self.pending_events.lock().unwrap();
1390 #[cfg(debug_assertions)] {
1391 for ev in pending_events.intercepted_msgs.iter() {
1392 if let Event::OnionMessageIntercepted { .. } = ev {} else { panic!(); }
1394 for ev in pending_events.peer_connecteds.iter() {
1395 if let Event::OnionMessagePeerConnected { .. } = ev {} else { panic!(); }
1398 core::mem::swap(&mut pending_events.intercepted_msgs, &mut events);
1399 events.append(&mut pending_events.peer_connecteds);
1400 pending_events.peer_connecteds.shrink_to(10); // Limit total heap usage
1403 handler.handle_event(ev);
1408 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
1409 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
1411 ES::Target: EntropySource,
1412 NS::Target: NodeSigner,
1414 NL::Target: NodeIdLookUp,
1415 MR::Target: MessageRouter,
1416 OMH::Target: OffersMessageHandler,
1417 CMH::Target: CustomOnionMessageHandler,
1419 fn handle_onion_message(&self, peer_node_id: &PublicKey, msg: &OnionMessage) {
1420 let logger = WithContext::from(&self.logger, Some(*peer_node_id), None, None);
1421 match self.peel_onion_message(msg) {
1422 Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
1425 "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
1426 path_id, if reply_path.is_some() { "a" } else { "no" }, message);
1429 ParsedOnionMessageContents::Offers(msg) => {
1430 let responder = reply_path.map(
1431 |reply_path| Responder::new(reply_path, path_id)
1433 let response_instructions = self.offers_handler.handle_message(msg, responder);
1434 let _ = self.handle_onion_message_response(response_instructions);
1436 ParsedOnionMessageContents::Custom(msg) => {
1437 let responder = reply_path.map(
1438 |reply_path| Responder::new(reply_path, path_id)
1440 let response_instructions = self.custom_handler.handle_custom_message(msg, responder);
1441 let _ = self.handle_onion_message_response(response_instructions);
1445 Ok(PeeledOnion::Forward(next_hop, onion_message)) => {
1446 let next_node_id = match next_hop {
1447 NextMessageHop::NodeId(pubkey) => pubkey,
1448 NextMessageHop::ShortChannelId(scid) => match self.node_id_lookup.next_node_id(scid) {
1449 Some(pubkey) => pubkey,
1451 log_trace!(self.logger, "Dropping forwarded onion messager: unable to resolve next hop using SCID {}", scid);
1457 let mut message_recipients = self.message_recipients.lock().unwrap();
1458 if outbound_buffer_full(&next_node_id, &message_recipients) {
1461 "Dropping forwarded onion message to peer {}: outbound buffer full",
1468 .entry(next_node_id)
1469 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
1471 match message_recipients.entry(next_node_id) {
1472 hash_map::Entry::Occupied(mut e) if matches!(
1473 e.get(), OnionMessageRecipient::ConnectedPeer(..)
1475 e.get_mut().enqueue_message(onion_message);
1476 log_trace!(logger, "Forwarding an onion message to peer {}", next_node_id);
1478 _ if self.intercept_messages_for_offline_peers => {
1479 self.enqueue_intercepted_event(
1480 Event::OnionMessageIntercepted {
1481 peer_node_id: next_node_id, message: onion_message
1488 "Dropping forwarded onion message to disconnected peer {}",
1495 log_error!(logger, "Failed to process onion message {:?}", e);
1500 fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
1501 if init.features.supports_onion_messages() {
1502 self.message_recipients.lock().unwrap()
1503 .entry(*their_node_id)
1504 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
1506 if self.intercept_messages_for_offline_peers {
1507 self.pending_events.lock().unwrap().peer_connecteds.push(
1508 Event::OnionMessagePeerConnected { peer_node_id: *their_node_id }
1512 self.message_recipients.lock().unwrap().remove(their_node_id);
1518 fn peer_disconnected(&self, their_node_id: &PublicKey) {
1519 match self.message_recipients.lock().unwrap().remove(their_node_id) {
1520 Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
1521 Some(_) => debug_assert!(false),
1526 fn timer_tick_occurred(&self) {
1527 let mut message_recipients = self.message_recipients.lock().unwrap();
1529 // Drop any pending recipients since the last call to avoid retaining buffered messages for
1531 message_recipients.retain(|_, recipient| match recipient {
1532 OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
1533 OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
1537 // Increment a timer tick for pending recipients so that their buffered messages are dropped
1538 // at MAX_TIMER_TICKS.
1539 for recipient in message_recipients.values_mut() {
1540 if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
1546 fn provided_node_features(&self) -> NodeFeatures {
1547 let mut features = NodeFeatures::empty();
1548 features.set_onion_messages_optional();
1552 fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1553 let mut features = InitFeatures::empty();
1554 features.set_onion_messages_optional();
1558 // Before returning any messages to send for the peer, this method will see if any messages were
1559 // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1560 // node, and then enqueue the message for sending to the first peer in the full path.
1561 fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1562 // Enqueue any initiating `OffersMessage`s to send.
1563 for message in self.offers_handler.release_pending_messages() {
1564 #[cfg(not(c_bindings))]
1565 let PendingOnionMessage { contents, destination, reply_path } = message;
1567 let (contents, destination, reply_path) = message;
1568 let _ = self.find_path_and_enqueue_onion_message(
1569 contents, destination, reply_path, format_args!("when sending OffersMessage")
1573 // Enqueue any initiating `CustomMessage`s to send.
1574 for message in self.custom_handler.release_pending_custom_messages() {
1575 #[cfg(not(c_bindings))]
1576 let PendingOnionMessage { contents, destination, reply_path } = message;
1578 let (contents, destination, reply_path) = message;
1579 let _ = self.find_path_and_enqueue_onion_message(
1580 contents, destination, reply_path, format_args!("when sending CustomMessage")
1584 self.message_recipients.lock().unwrap()
1585 .get_mut(&peer_node_id)
1586 .and_then(|buffer| buffer.dequeue_message())
1590 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1592 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1593 /// [`SimpleArcPeerManager`]. See their docs for more details.
1595 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1597 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1598 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1599 #[cfg(not(c_bindings))]
1600 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1604 Arc<SimpleArcChannelManager<M, T, F, L>>,
1605 Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>, Arc<KeysManager>>>,
1606 Arc<SimpleArcChannelManager<M, T, F, L>>,
1607 IgnoringMessageHandler
1610 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1611 /// [`SimpleRefPeerManager`]. See their docs for more details.
1613 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1615 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1616 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1617 #[cfg(not(c_bindings))]
1618 pub type SimpleRefOnionMessenger<
1619 'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1624 &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1625 &'j DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L, &'a KeysManager>,
1626 &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1627 IgnoringMessageHandler
1630 /// Construct onion packet payloads and keys for sending an onion message along the given
1631 /// `unblinded_path` to the given `destination`.
1632 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1633 secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1634 mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1635 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), SendError> {
1636 let num_hops = unblinded_path.len() + destination.num_hops();
1637 let mut payloads = Vec::with_capacity(num_hops);
1638 let mut onion_packet_keys = Vec::with_capacity(num_hops);
1640 let (mut intro_node_id_blinding_pt, num_blinded_hops) = match &destination {
1641 Destination::Node(_) => (None, 0),
1642 Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, blinded_hops }) => {
1643 let introduction_node_id = match introduction_node {
1644 IntroductionNode::NodeId(pubkey) => pubkey,
1645 IntroductionNode::DirectedShortChannelId(..) => {
1646 return Err(SendError::UnresolvedIntroductionNode);
1649 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len())
1652 let num_unblinded_hops = num_hops - num_blinded_hops;
1654 let mut unblinded_path_idx = 0;
1655 let mut blinded_path_idx = 0;
1656 let mut prev_control_tlvs_ss = None;
1657 let mut final_control_tlvs = None;
1658 utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1659 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1660 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1661 if let Some(ss) = prev_control_tlvs_ss.take() {
1662 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1664 next_hop: NextMessageHop::NodeId(unblinded_pk_opt.unwrap()),
1665 next_blinding_override: None,
1669 prev_control_tlvs_ss = Some(control_tlvs_ss);
1670 unblinded_path_idx += 1;
1671 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1672 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1673 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1674 next_hop: NextMessageHop::NodeId(intro_node_id),
1675 next_blinding_override: Some(blinding_pt),
1676 })), control_tlvs_ss));
1679 if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1680 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1682 blinded_path_idx += 1;
1683 } else if let Some(encrypted_payload) = enc_payload_opt {
1684 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1685 prev_control_tlvs_ss = Some(control_tlvs_ss);
1688 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1689 onion_packet_keys.push(onion_utils::OnionKeys {
1691 shared_secret: onion_packet_ss,
1693 blinding_factor: [0; 32],
1699 ).map_err(|e| SendError::Secp256k1(e))?;
1701 if let Some(control_tlvs) = final_control_tlvs {
1702 payloads.push((Payload::Receive {
1704 reply_path: reply_path.take(),
1706 }, prev_control_tlvs_ss.unwrap()));
1708 payloads.push((Payload::Receive {
1709 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1710 reply_path: reply_path.take(),
1712 }, prev_control_tlvs_ss.unwrap()));
1715 Ok((payloads, onion_packet_keys))
1718 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1719 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, ()> {
1721 // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1722 // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1723 // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1724 let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1725 let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1726 SMALL_PACKET_HOP_DATA_LEN
1727 } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1728 BIG_PACKET_HOP_DATA_LEN
1729 } else { return Err(()) };
1731 onion_utils::construct_onion_message_packet::<_, _>(
1732 payloads, onion_keys, prng_seed, hop_data_len)