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: Iterator<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 mut peer_info = peers
509 // Limit to peers with announced channels
512 .node(&NodeId::from_pubkey(&peer.node_id))
513 .filter(|info| info.channels.len() >= MIN_PEER_CHANNELS)
514 .map(|info| (peer, info.is_tor_only(), info.channels.len()))
516 // Exclude Tor-only nodes when the recipient is announced.
517 .filter(|(_, is_tor_only, _)| !(*is_tor_only && is_recipient_announced))
518 .collect::<Vec<_>>();
520 // Prefer using non-Tor nodes with the most channels as the introduction node.
521 peer_info.sort_unstable_by(|(_, a_tor_only, a_channels), (_, b_tor_only, b_channels)| {
522 a_tor_only.cmp(b_tor_only).then(a_channels.cmp(b_channels).reverse())
525 let paths = peer_info.into_iter()
526 .map(|(peer, _, _)| {
527 BlindedPath::new_for_message(&[peer], recipient, &*self.entropy_source, secp_ctx)
530 .collect::<Result<Vec<_>, _>>();
532 let mut paths = match paths {
533 Ok(paths) if !paths.is_empty() => Ok(paths),
535 if is_recipient_announced {
536 BlindedPath::one_hop_for_message(recipient, &*self.entropy_source, secp_ctx)
537 .map(|path| vec![path])
545 for path in &mut paths {
546 path.use_compact_introduction_node(&network_graph);
554 impl<G: Deref<Target=NetworkGraph<L>>, L: Deref, ES: Deref> MessageRouter for DefaultMessageRouter<G, L, ES>
557 ES::Target: EntropySource,
560 &self, sender: PublicKey, peers: Vec<PublicKey>, mut destination: Destination
561 ) -> Result<OnionMessagePath, ()> {
562 let network_graph = self.network_graph.deref().read_only();
563 destination.resolve(&network_graph);
565 let first_node = match destination.first_node() {
566 Some(first_node) => first_node,
567 None => return Err(()),
570 if peers.contains(&first_node) || sender == first_node {
571 Ok(OnionMessagePath {
572 intermediate_nodes: vec![], destination, first_node_addresses: None
575 let node_details = network_graph
576 .node(&NodeId::from_pubkey(&first_node))
577 .and_then(|node_info| node_info.announcement_info.as_ref())
578 .map(|announcement_info| (announcement_info.features(), announcement_info.addresses()));
581 Some((features, addresses)) if features.supports_onion_messages() && addresses.len() > 0 => {
582 let first_node_addresses = Some(addresses.clone());
583 Ok(OnionMessagePath {
584 intermediate_nodes: vec![], destination, first_node_addresses
592 fn create_blinded_paths<
593 T: secp256k1::Signing + secp256k1::Verification
595 &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
596 ) -> Result<Vec<BlindedPath>, ()> {
599 .map(|node_id| ForwardNode { node_id, short_channel_id: None });
600 self.create_blinded_paths_from_iter(recipient, peers, secp_ctx, false)
603 fn create_compact_blinded_paths<
604 T: secp256k1::Signing + secp256k1::Verification
606 &self, recipient: PublicKey, peers: Vec<ForwardNode>, secp_ctx: &Secp256k1<T>,
607 ) -> Result<Vec<BlindedPath>, ()> {
608 self.create_blinded_paths_from_iter(recipient, peers.into_iter(), secp_ctx, true)
612 /// A path for sending an [`OnionMessage`].
614 pub struct OnionMessagePath {
615 /// Nodes on the path between the sender and the destination.
616 pub intermediate_nodes: Vec<PublicKey>,
618 /// The recipient of the message.
619 pub destination: Destination,
621 /// Addresses that may be used to connect to [`OnionMessagePath::first_node`].
623 /// Only needs to be set if a connection to the node is required. [`OnionMessenger`] may use
624 /// this to initiate such a connection.
625 pub first_node_addresses: Option<Vec<SocketAddress>>,
628 impl OnionMessagePath {
629 /// Returns the first node in the path.
630 pub fn first_node(&self) -> Option<PublicKey> {
631 self.intermediate_nodes
634 .or_else(|| self.destination.first_node())
638 /// The destination of an onion message.
639 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
640 pub enum Destination {
641 /// We're sending this onion message to a node.
643 /// We're sending this onion message to a blinded path.
644 BlindedPath(BlindedPath),
648 /// Attempts to resolve the [`IntroductionNode::DirectedShortChannelId`] of a
649 /// [`Destination::BlindedPath`] to a [`IntroductionNode::NodeId`], if applicable, using the
650 /// provided [`ReadOnlyNetworkGraph`].
651 pub fn resolve(&mut self, network_graph: &ReadOnlyNetworkGraph) {
652 if let Destination::BlindedPath(path) = self {
653 if let IntroductionNode::DirectedShortChannelId(..) = path.introduction_node {
654 if let Some(pubkey) = path
655 .public_introduction_node_id(network_graph)
656 .and_then(|node_id| node_id.as_pubkey().ok())
658 path.introduction_node = IntroductionNode::NodeId(pubkey);
664 pub(super) fn num_hops(&self) -> usize {
666 Destination::Node(_) => 1,
667 Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
671 fn first_node(&self) -> Option<PublicKey> {
673 Destination::Node(node_id) => Some(*node_id),
674 Destination::BlindedPath(BlindedPath { introduction_node, .. }) => {
675 match introduction_node {
676 IntroductionNode::NodeId(pubkey) => Some(*pubkey),
677 IntroductionNode::DirectedShortChannelId(..) => None,
684 /// Result of successfully [sending an onion message].
686 /// [sending an onion message]: OnionMessenger::send_onion_message
687 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
688 pub enum SendSuccess {
689 /// The message was buffered and will be sent once it is processed by
690 /// [`OnionMessageHandler::next_onion_message_for_peer`].
692 /// The message was buffered and will be sent once the node is connected as a peer and it is
693 /// processed by [`OnionMessageHandler::next_onion_message_for_peer`].
694 BufferedAwaitingConnection(PublicKey),
697 /// Errors that may occur when [sending an onion message].
699 /// [sending an onion message]: OnionMessenger::send_onion_message
700 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
702 /// Errored computing onion message packet keys.
703 Secp256k1(secp256k1::Error),
704 /// Because implementations such as Eclair will drop onion messages where the message packet
705 /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
707 /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
710 /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
711 InvalidFirstHop(PublicKey),
712 /// Indicates that a path could not be found by the [`MessageRouter`].
714 /// This occurs when either:
715 /// - No path from the sender to the destination was found to send the onion message
716 /// - No reply path to the sender could be created when responding to an onion message
718 /// Onion message contents must have a TLV type >= 64.
720 /// Our next-hop peer's buffer was full or our total outbound buffer was full.
722 /// Failed to retrieve our node id from the provided [`NodeSigner`].
724 /// [`NodeSigner`]: crate::sign::NodeSigner
726 /// The provided [`Destination`] has a blinded path with an unresolved introduction node. An
727 /// attempt to resolve it in the [`MessageRouter`] when finding an [`OnionMessagePath`] likely
729 UnresolvedIntroductionNode,
730 /// We attempted to send to a blinded path where we are the introduction node, and failed to
731 /// advance the blinded path to make the second hop the new introduction node. Either
732 /// [`NodeSigner::ecdh`] failed, we failed to tweak the current blinding point to get the
733 /// new blinding point, or we were attempting to send to ourselves.
734 BlindedPathAdvanceFailed,
737 /// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`],
738 /// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages,
739 /// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom
740 /// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported
743 /// See [`OnionMessenger`] for example usage.
745 /// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler
746 /// [`CustomMessage`]: Self::CustomMessage
747 pub trait CustomOnionMessageHandler {
748 /// The message known to the handler. To support multiple message types, you may want to make this
749 /// an enum with a variant for each supported message.
750 type CustomMessage: OnionMessageContents;
752 /// Called with the custom message that was received, returning a response to send, if any.
754 /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
755 fn handle_custom_message(&self, message: Self::CustomMessage, responder: Option<Responder>) -> ResponseInstruction<Self::CustomMessage>;
757 /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
758 /// message type is unknown.
759 fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
761 /// Releases any [`Self::CustomMessage`]s that need to be sent.
763 /// Typically, this is used for messages initiating a message flow rather than in response to
764 /// another message. The latter should use the return value of [`Self::handle_custom_message`].
765 #[cfg(not(c_bindings))]
766 fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
768 /// Releases any [`Self::CustomMessage`]s that need to be sent.
770 /// Typically, this is used for messages initiating a message flow rather than in response to
771 /// another message. The latter should use the return value of [`Self::handle_custom_message`].
773 fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
776 /// A processed incoming onion message, containing either a Forward (another onion message)
777 /// or a Receive payload with decrypted contents.
778 #[derive(Clone, Debug)]
779 pub enum PeeledOnion<T: OnionMessageContents> {
780 /// Forwarded onion, with the next node id and a new onion
781 Forward(NextMessageHop, OnionMessage),
782 /// Received onion message, with decrypted contents, path_id, and reply path
783 Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
787 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
788 /// `path`, first calling [`Destination::resolve`] on `path.destination` with the given
789 /// [`ReadOnlyNetworkGraph`].
791 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
792 /// needed to connect to the first node.
793 pub fn create_onion_message_resolving_destination<
794 ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents
796 entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
797 network_graph: &ReadOnlyNetworkGraph, secp_ctx: &Secp256k1<secp256k1::All>,
798 mut path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
799 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
801 ES::Target: EntropySource,
802 NS::Target: NodeSigner,
803 NL::Target: NodeIdLookUp,
805 path.destination.resolve(network_graph);
806 create_onion_message(
807 entropy_source, node_signer, node_id_lookup, secp_ctx, path, contents, reply_path,
811 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
814 /// Returns the node id of the peer to send the message to, the message itself, and any addresses
815 /// needed to connect to the first node.
817 /// Returns [`SendError::UnresolvedIntroductionNode`] if:
818 /// - `destination` contains a blinded path with an [`IntroductionNode::DirectedShortChannelId`],
819 /// - unless it can be resolved by [`NodeIdLookUp::next_node_id`].
820 /// Use [`create_onion_message_resolving_destination`] instead to resolve the introduction node
821 /// first with a [`ReadOnlyNetworkGraph`].
822 pub fn create_onion_message<ES: Deref, NS: Deref, NL: Deref, T: OnionMessageContents>(
823 entropy_source: &ES, node_signer: &NS, node_id_lookup: &NL,
824 secp_ctx: &Secp256k1<secp256k1::All>, path: OnionMessagePath, contents: T,
825 reply_path: Option<BlindedPath>,
826 ) -> Result<(PublicKey, OnionMessage, Option<Vec<SocketAddress>>), SendError>
828 ES::Target: EntropySource,
829 NS::Target: NodeSigner,
830 NL::Target: NodeIdLookUp,
832 let OnionMessagePath { intermediate_nodes, mut destination, first_node_addresses } = path;
833 if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
834 if blinded_hops.is_empty() {
835 return Err(SendError::TooFewBlindedHops);
839 if contents.tlv_type() < 64 { return Err(SendError::InvalidMessage) }
841 // If we are sending straight to a blinded path and we are the introduction node, we need to
842 // advance the blinded path by 1 hop so the second hop is the new introduction node.
843 if intermediate_nodes.len() == 0 {
844 if let Destination::BlindedPath(ref mut blinded_path) = destination {
845 let our_node_id = node_signer.get_node_id(Recipient::Node)
846 .map_err(|()| SendError::GetNodeIdFailed)?;
847 let introduction_node_id = match blinded_path.introduction_node {
848 IntroductionNode::NodeId(pubkey) => pubkey,
849 IntroductionNode::DirectedShortChannelId(direction, scid) => {
850 match node_id_lookup.next_node_id(scid) {
851 Some(next_node_id) => *direction.select_pubkey(&our_node_id, &next_node_id),
852 None => return Err(SendError::UnresolvedIntroductionNode),
856 if introduction_node_id == our_node_id {
857 advance_path_by_one(blinded_path, node_signer, node_id_lookup, &secp_ctx)
858 .map_err(|()| SendError::BlindedPathAdvanceFailed)?;
863 let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
864 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
865 let (first_node_id, blinding_point) = if let Some(first_node_id) = intermediate_nodes.first() {
866 (*first_node_id, PublicKey::from_secret_key(&secp_ctx, &blinding_secret))
869 Destination::Node(pk) => (*pk, PublicKey::from_secret_key(&secp_ctx, &blinding_secret)),
870 Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, .. }) => {
871 match introduction_node {
872 IntroductionNode::NodeId(pubkey) => (*pubkey, *blinding_point),
873 IntroductionNode::DirectedShortChannelId(..) => {
874 return Err(SendError::UnresolvedIntroductionNode);
880 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
881 &secp_ctx, &intermediate_nodes, destination, contents, reply_path, &blinding_secret
884 let prng_seed = entropy_source.get_secure_random_bytes();
885 let onion_routing_packet = construct_onion_message_packet(
886 packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?;
888 let message = OnionMessage { blinding_point, onion_routing_packet };
889 Ok((first_node_id, message, first_node_addresses))
892 /// Decode one layer of an incoming [`OnionMessage`].
894 /// Returns either the next layer of the onion for forwarding or the decrypted content for the
896 pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
897 msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
899 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
901 NS::Target: NodeSigner,
903 CMH::Target: CustomOnionMessageHandler,
905 let control_tlvs_ss = match node_signer.ecdh(Recipient::Node, &msg.blinding_point, None) {
908 log_error!(logger, "Failed to retrieve node secret: {:?}", e);
912 let onion_decode_ss = {
913 let blinding_factor = {
914 let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
915 hmac.input(control_tlvs_ss.as_ref());
916 Hmac::from_engine(hmac).to_byte_array()
918 match node_signer.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key,
919 Some(&Scalar::from_be_bytes(blinding_factor).unwrap()))
921 Ok(ss) => ss.secret_bytes(),
923 log_trace!(logger, "Failed to compute onion packet shared secret");
928 match onion_utils::decode_next_untagged_hop(
929 onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
930 (control_tlvs_ss, custom_handler.deref(), logger.deref())
932 Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
933 message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
935 Ok(PeeledOnion::Receive(message, path_id, reply_path))
937 Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
938 next_hop, next_blinding_override
939 })), Some((next_hop_hmac, new_packet_bytes)))) => {
940 // TODO: we need to check whether `next_hop` is our node, in which case this is a dummy
941 // blinded hop and this onion message is destined for us. In this situation, we should keep
942 // unwrapping the onion layers to get to the final payload. Since we don't have the option
943 // of creating blinded paths with dummy hops currently, we should be ok to not handle this
945 let new_pubkey = match onion_utils::next_hop_pubkey(&secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) {
948 log_trace!(logger, "Failed to compute next hop packet pubkey: {}", e);
952 let outgoing_packet = Packet {
954 public_key: new_pubkey,
955 hop_data: new_packet_bytes,
958 let onion_message = OnionMessage {
959 blinding_point: match next_blinding_override {
960 Some(blinding_point) => blinding_point,
962 match onion_utils::next_hop_pubkey(
963 &secp_ctx, msg.blinding_point, control_tlvs_ss.as_ref()
967 log_trace!(logger, "Failed to compute next blinding point: {}", e);
973 onion_routing_packet: outgoing_packet,
976 Ok(PeeledOnion::Forward(next_hop, onion_message))
979 log_trace!(logger, "Errored decoding onion message packet: {:?}", e);
983 log_trace!(logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa");
989 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref>
990 OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
992 ES::Target: EntropySource,
993 NS::Target: NodeSigner,
995 NL::Target: NodeIdLookUp,
996 MR::Target: MessageRouter,
997 OMH::Target: OffersMessageHandler,
998 CMH::Target: CustomOnionMessageHandler,
1000 /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
1001 /// their respective handlers.
1003 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL, message_router: MR,
1004 offers_handler: OMH, custom_handler: CMH
1007 entropy_source, node_signer, logger, node_id_lookup, message_router,
1008 offers_handler, custom_handler, false
1012 /// Similar to [`Self::new`], but rather than dropping onion messages that are
1013 /// intended to be forwarded to offline peers, we will intercept them for
1014 /// later forwarding.
1016 /// Interception flow:
1017 /// 1. If an onion message for an offline peer is received, `OnionMessenger` will
1018 /// generate an [`Event::OnionMessageIntercepted`]. Event handlers can
1019 /// then choose to persist this onion message for later forwarding, or drop
1021 /// 2. When the offline peer later comes back online, `OnionMessenger` will
1022 /// generate an [`Event::OnionMessagePeerConnected`]. Event handlers will
1023 /// then fetch all previously intercepted onion messages for this peer.
1024 /// 3. Once the stored onion messages are fetched, they can finally be
1025 /// forwarded to the now-online peer via [`Self::forward_onion_message`].
1029 /// LDK will not rate limit how many [`Event::OnionMessageIntercepted`]s
1030 /// are generated, so it is the caller's responsibility to limit how many
1031 /// onion messages are persisted and only persist onion messages for relevant
1033 pub fn new_with_offline_peer_interception(
1034 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL,
1035 message_router: MR, offers_handler: OMH, custom_handler: CMH
1038 entropy_source, node_signer, logger, node_id_lookup, message_router,
1039 offers_handler, custom_handler, true
1044 entropy_source: ES, node_signer: NS, logger: L, node_id_lookup: NL,
1045 message_router: MR, offers_handler: OMH, custom_handler: CMH,
1046 intercept_messages_for_offline_peers: bool
1048 let mut secp_ctx = Secp256k1::new();
1049 secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
1053 message_recipients: Mutex::new(new_hash_map()),
1060 intercept_messages_for_offline_peers,
1061 pending_events: Mutex::new(PendingEvents {
1062 intercepted_msgs: Vec::new(),
1063 peer_connecteds: Vec::new(),
1069 pub(crate) fn set_offers_handler(&mut self, offers_handler: OMH) {
1070 self.offers_handler = offers_handler;
1073 /// Sends an [`OnionMessage`] with the given `contents` to `destination`.
1075 /// See [`OnionMessenger`] for example usage.
1076 pub fn send_onion_message<T: OnionMessageContents>(
1077 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>
1078 ) -> Result<SendSuccess, SendError> {
1079 self.find_path_and_enqueue_onion_message(
1080 contents, destination, reply_path, format_args!("")
1084 fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
1085 &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
1086 log_suffix: fmt::Arguments
1087 ) -> Result<SendSuccess, SendError> {
1088 let mut logger = WithContext::from(&self.logger, None, None, None);
1089 let result = self.find_path(destination).and_then(|path| {
1090 let first_hop = path.intermediate_nodes.get(0).map(|p| *p);
1091 logger = WithContext::from(&self.logger, first_hop, None, None);
1092 self.enqueue_onion_message(path, contents, reply_path, log_suffix)
1095 match result.as_ref() {
1096 Err(SendError::GetNodeIdFailed) => {
1097 log_warn!(logger, "Unable to retrieve node id {}", log_suffix);
1099 Err(SendError::PathNotFound) => {
1100 log_trace!(logger, "Failed to find path {}", log_suffix);
1103 log_trace!(logger, "Failed sending onion message {}: {:?}", log_suffix, e);
1105 Ok(SendSuccess::Buffered) => {
1106 log_trace!(logger, "Buffered onion message {}", log_suffix);
1108 Ok(SendSuccess::BufferedAwaitingConnection(node_id)) => {
1111 "Buffered onion message waiting on peer connection {}: {}",
1120 fn find_path(&self, destination: Destination) -> Result<OnionMessagePath, SendError> {
1121 let sender = self.node_signer
1122 .get_node_id(Recipient::Node)
1123 .map_err(|_| SendError::GetNodeIdFailed)?;
1125 let peers = self.message_recipients.lock().unwrap()
1127 .filter(|(_, recipient)| matches!(recipient, OnionMessageRecipient::ConnectedPeer(_)))
1128 .map(|(node_id, _)| *node_id)
1132 .find_path(sender, peers, destination)
1133 .map_err(|_| SendError::PathNotFound)
1136 fn create_blinded_path(&self) -> Result<BlindedPath, SendError> {
1137 let recipient = self.node_signer
1138 .get_node_id(Recipient::Node)
1139 .map_err(|_| SendError::GetNodeIdFailed)?;
1140 let secp_ctx = &self.secp_ctx;
1142 let peers = self.message_recipients.lock().unwrap()
1144 .filter(|(_, peer)| matches!(peer, OnionMessageRecipient::ConnectedPeer(_)))
1145 .map(|(node_id, _ )| *node_id)
1146 .collect::<Vec<_>>();
1149 .create_blinded_paths(recipient, peers, secp_ctx)
1150 .and_then(|paths| paths.into_iter().next().ok_or(()))
1151 .map_err(|_| SendError::PathNotFound)
1154 fn enqueue_onion_message<T: OnionMessageContents>(
1155 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
1156 log_suffix: fmt::Arguments
1157 ) -> Result<SendSuccess, SendError> {
1158 log_trace!(self.logger, "Constructing onion message {}: {:?}", log_suffix, contents);
1160 let (first_node_id, onion_message, addresses) = create_onion_message(
1161 &self.entropy_source, &self.node_signer, &self.node_id_lookup, &self.secp_ctx, path,
1162 contents, reply_path,
1165 let mut message_recipients = self.message_recipients.lock().unwrap();
1166 if outbound_buffer_full(&first_node_id, &message_recipients) {
1167 return Err(SendError::BufferFull);
1170 match message_recipients.entry(first_node_id) {
1171 hash_map::Entry::Vacant(e) => match addresses {
1172 None => Err(SendError::InvalidFirstHop(first_node_id)),
1173 Some(addresses) => {
1174 e.insert(OnionMessageRecipient::pending_connection(addresses))
1175 .enqueue_message(onion_message);
1176 Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
1179 hash_map::Entry::Occupied(mut e) => {
1180 e.get_mut().enqueue_message(onion_message);
1181 if e.get().is_connected() {
1182 Ok(SendSuccess::Buffered)
1184 Ok(SendSuccess::BufferedAwaitingConnection(first_node_id))
1190 /// Forwards an [`OnionMessage`] to `peer_node_id`. Useful if we initialized
1191 /// the [`OnionMessenger`] with [`Self::new_with_offline_peer_interception`]
1192 /// and want to forward a previously intercepted onion message to a peer that
1193 /// has just come online.
1194 pub fn forward_onion_message(
1195 &self, message: OnionMessage, peer_node_id: &PublicKey
1196 ) -> Result<(), SendError> {
1197 let mut message_recipients = self.message_recipients.lock().unwrap();
1198 if outbound_buffer_full(&peer_node_id, &message_recipients) {
1199 return Err(SendError::BufferFull);
1202 match message_recipients.entry(*peer_node_id) {
1203 hash_map::Entry::Occupied(mut e) if e.get().is_connected() => {
1204 e.get_mut().enqueue_message(message);
1207 _ => Err(SendError::InvalidFirstHop(*peer_node_id))
1211 #[cfg(any(test, feature = "_test_utils"))]
1212 pub fn send_onion_message_using_path<T: OnionMessageContents>(
1213 &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
1214 ) -> Result<SendSuccess, SendError> {
1215 self.enqueue_onion_message(path, contents, reply_path, format_args!(""))
1218 pub(crate) fn peel_onion_message(
1219 &self, msg: &OnionMessage
1220 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()> {
1222 msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
1226 /// Handles the response to an [`OnionMessage`] based on its [`ResponseInstruction`],
1227 /// enqueueing any response for sending.
1229 /// This function is useful for asynchronous handling of [`OnionMessage`]s.
1230 /// Handlers have the option to return [`ResponseInstruction::NoResponse`], indicating that
1231 /// no immediate response should be sent. Then, they can transfer the associated [`Responder`]
1232 /// to another task responsible for generating the response asynchronously. Subsequently, when
1233 /// the response is prepared and ready for sending, that task can invoke this method to enqueue
1234 /// the response for delivery.
1235 pub fn handle_onion_message_response<T: OnionMessageContents>(
1236 &self, response: ResponseInstruction<T>
1237 ) -> Result<Option<SendSuccess>, SendError> {
1238 let (response, create_reply_path) = match response {
1239 ResponseInstruction::WithReplyPath(response) => (response, true),
1240 ResponseInstruction::WithoutReplyPath(response) => (response, false),
1241 ResponseInstruction::NoResponse => return Ok(None),
1244 let message_type = response.message.msg_type();
1245 let reply_path = if create_reply_path {
1246 match self.create_blinded_path() {
1247 Ok(reply_path) => Some(reply_path),
1251 "Failed to create reply path when responding with {} to an onion message \
1252 with path_id {:02x?}: {:?}",
1253 message_type, response.path_id, err
1260 self.find_path_and_enqueue_onion_message(
1261 response.message, Destination::BlindedPath(response.reply_path), reply_path,
1263 "when responding with {} to an onion message with path_id {:02x?}",
1267 ).map(|result| Some(result))
1271 pub(super) fn release_pending_msgs(&self) -> HashMap<PublicKey, VecDeque<OnionMessage>> {
1272 let mut message_recipients = self.message_recipients.lock().unwrap();
1273 let mut msgs = new_hash_map();
1274 // We don't want to disconnect the peers by removing them entirely from the original map, so we
1275 // release the pending message buffers individually.
1276 for (node_id, recipient) in &mut *message_recipients {
1277 msgs.insert(*node_id, recipient.release_pending_messages());
1282 fn enqueue_intercepted_event(&self, event: Event) {
1283 const MAX_EVENTS_BUFFER_SIZE: usize = (1 << 10) * 256;
1284 let mut pending_events = self.pending_events.lock().unwrap();
1285 let total_buffered_bytes: usize =
1286 pending_events.intercepted_msgs.iter().map(|ev| ev.serialized_length()).sum();
1287 if total_buffered_bytes >= MAX_EVENTS_BUFFER_SIZE {
1288 log_trace!(self.logger, "Dropping event {:?}: buffer full", event);
1291 pending_events.intercepted_msgs.push(event);
1294 /// Processes any events asynchronously using the given handler.
1296 /// Note that the event handler is called in the order each event was generated, however
1297 /// futures are polled in parallel for some events to allow for parallelism where events do not
1298 /// have an ordering requirement.
1300 /// See the trait-level documentation of [`EventsProvider`] for requirements.
1301 pub async fn process_pending_events_async<Future: core::future::Future<Output = ()> + core::marker::Unpin, H: Fn(Event) -> Future>(
1304 let mut intercepted_msgs = Vec::new();
1305 let mut peer_connecteds = Vec::new();
1307 let mut pending_events = self.pending_events.lock().unwrap();
1308 core::mem::swap(&mut pending_events.intercepted_msgs, &mut intercepted_msgs);
1309 core::mem::swap(&mut pending_events.peer_connecteds, &mut peer_connecteds);
1312 let mut futures = Vec::with_capacity(intercepted_msgs.len());
1313 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
1314 if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
1315 if let Some(addresses) = addresses.take() {
1316 futures.push(Some(handler(Event::ConnectionNeeded { node_id: *node_id, addresses })));
1321 for ev in intercepted_msgs {
1322 if let Event::OnionMessageIntercepted { .. } = ev {} else { debug_assert!(false); }
1323 futures.push(Some(handler(ev)));
1325 // Let the `OnionMessageIntercepted` events finish before moving on to peer_connecteds
1326 crate::util::async_poll::MultiFuturePoller(futures).await;
1328 if peer_connecteds.len() <= 1 {
1329 for event in peer_connecteds { handler(event).await; }
1331 let mut futures = Vec::new();
1332 for event in peer_connecteds {
1333 futures.push(Some(handler(event)));
1335 crate::util::async_poll::MultiFuturePoller(futures).await;
1340 fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap<PublicKey, OnionMessageRecipient>) -> bool {
1341 const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128;
1342 const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256;
1343 let mut total_buffered_bytes = 0;
1344 let mut peer_buffered_bytes = 0;
1345 for (pk, peer_buf) in buffer {
1346 for om in peer_buf.pending_messages() {
1347 let om_len = om.serialized_length();
1348 if pk == peer_node_id {
1349 peer_buffered_bytes += om_len;
1351 total_buffered_bytes += om_len;
1353 if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE ||
1354 peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE
1363 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> EventsProvider
1364 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
1366 ES::Target: EntropySource,
1367 NS::Target: NodeSigner,
1369 NL::Target: NodeIdLookUp,
1370 MR::Target: MessageRouter,
1371 OMH::Target: OffersMessageHandler,
1372 CMH::Target: CustomOnionMessageHandler,
1374 fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
1375 for (node_id, recipient) in self.message_recipients.lock().unwrap().iter_mut() {
1376 if let OnionMessageRecipient::PendingConnection(_, addresses, _) = recipient {
1377 if let Some(addresses) = addresses.take() {
1378 handler.handle_event(Event::ConnectionNeeded { node_id: *node_id, addresses });
1382 let mut events = Vec::new();
1384 let mut pending_events = self.pending_events.lock().unwrap();
1385 #[cfg(debug_assertions)] {
1386 for ev in pending_events.intercepted_msgs.iter() {
1387 if let Event::OnionMessageIntercepted { .. } = ev {} else { panic!(); }
1389 for ev in pending_events.peer_connecteds.iter() {
1390 if let Event::OnionMessagePeerConnected { .. } = ev {} else { panic!(); }
1393 core::mem::swap(&mut pending_events.intercepted_msgs, &mut events);
1394 events.append(&mut pending_events.peer_connecteds);
1395 pending_events.peer_connecteds.shrink_to(10); // Limit total heap usage
1398 handler.handle_event(ev);
1403 impl<ES: Deref, NS: Deref, L: Deref, NL: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageHandler
1404 for OnionMessenger<ES, NS, L, NL, MR, OMH, CMH>
1406 ES::Target: EntropySource,
1407 NS::Target: NodeSigner,
1409 NL::Target: NodeIdLookUp,
1410 MR::Target: MessageRouter,
1411 OMH::Target: OffersMessageHandler,
1412 CMH::Target: CustomOnionMessageHandler,
1414 fn handle_onion_message(&self, peer_node_id: &PublicKey, msg: &OnionMessage) {
1415 let logger = WithContext::from(&self.logger, Some(*peer_node_id), None, None);
1416 match self.peel_onion_message(msg) {
1417 Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
1420 "Received an onion message with path_id {:02x?} and {} reply_path: {:?}",
1421 path_id, if reply_path.is_some() { "a" } else { "no" }, message);
1424 ParsedOnionMessageContents::Offers(msg) => {
1425 let responder = reply_path.map(
1426 |reply_path| Responder::new(reply_path, path_id)
1428 let response_instructions = self.offers_handler.handle_message(msg, responder);
1429 let _ = self.handle_onion_message_response(response_instructions);
1431 ParsedOnionMessageContents::Custom(msg) => {
1432 let responder = reply_path.map(
1433 |reply_path| Responder::new(reply_path, path_id)
1435 let response_instructions = self.custom_handler.handle_custom_message(msg, responder);
1436 let _ = self.handle_onion_message_response(response_instructions);
1440 Ok(PeeledOnion::Forward(next_hop, onion_message)) => {
1441 let next_node_id = match next_hop {
1442 NextMessageHop::NodeId(pubkey) => pubkey,
1443 NextMessageHop::ShortChannelId(scid) => match self.node_id_lookup.next_node_id(scid) {
1444 Some(pubkey) => pubkey,
1446 log_trace!(self.logger, "Dropping forwarded onion messager: unable to resolve next hop using SCID {}", scid);
1452 let mut message_recipients = self.message_recipients.lock().unwrap();
1453 if outbound_buffer_full(&next_node_id, &message_recipients) {
1456 "Dropping forwarded onion message to peer {}: outbound buffer full",
1463 .entry(next_node_id)
1464 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()));
1466 match message_recipients.entry(next_node_id) {
1467 hash_map::Entry::Occupied(mut e) if matches!(
1468 e.get(), OnionMessageRecipient::ConnectedPeer(..)
1470 e.get_mut().enqueue_message(onion_message);
1471 log_trace!(logger, "Forwarding an onion message to peer {}", next_node_id);
1473 _ if self.intercept_messages_for_offline_peers => {
1474 self.enqueue_intercepted_event(
1475 Event::OnionMessageIntercepted {
1476 peer_node_id: next_node_id, message: onion_message
1483 "Dropping forwarded onion message to disconnected peer {}",
1490 log_error!(logger, "Failed to process onion message {:?}", e);
1495 fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init, _inbound: bool) -> Result<(), ()> {
1496 if init.features.supports_onion_messages() {
1497 self.message_recipients.lock().unwrap()
1498 .entry(*their_node_id)
1499 .or_insert_with(|| OnionMessageRecipient::ConnectedPeer(VecDeque::new()))
1501 if self.intercept_messages_for_offline_peers {
1502 self.pending_events.lock().unwrap().peer_connecteds.push(
1503 Event::OnionMessagePeerConnected { peer_node_id: *their_node_id }
1507 self.message_recipients.lock().unwrap().remove(their_node_id);
1513 fn peer_disconnected(&self, their_node_id: &PublicKey) {
1514 match self.message_recipients.lock().unwrap().remove(their_node_id) {
1515 Some(OnionMessageRecipient::ConnectedPeer(..)) => {},
1516 Some(_) => debug_assert!(false),
1521 fn timer_tick_occurred(&self) {
1522 let mut message_recipients = self.message_recipients.lock().unwrap();
1524 // Drop any pending recipients since the last call to avoid retaining buffered messages for
1526 message_recipients.retain(|_, recipient| match recipient {
1527 OnionMessageRecipient::PendingConnection(_, None, ticks) => *ticks < MAX_TIMER_TICKS,
1528 OnionMessageRecipient::PendingConnection(_, Some(_), _) => true,
1532 // Increment a timer tick for pending recipients so that their buffered messages are dropped
1533 // at MAX_TIMER_TICKS.
1534 for recipient in message_recipients.values_mut() {
1535 if let OnionMessageRecipient::PendingConnection(_, None, ticks) = recipient {
1541 fn provided_node_features(&self) -> NodeFeatures {
1542 let mut features = NodeFeatures::empty();
1543 features.set_onion_messages_optional();
1547 fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures {
1548 let mut features = InitFeatures::empty();
1549 features.set_onion_messages_optional();
1553 // Before returning any messages to send for the peer, this method will see if any messages were
1554 // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
1555 // node, and then enqueue the message for sending to the first peer in the full path.
1556 fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
1557 // Enqueue any initiating `OffersMessage`s to send.
1558 for message in self.offers_handler.release_pending_messages() {
1559 #[cfg(not(c_bindings))]
1560 let PendingOnionMessage { contents, destination, reply_path } = message;
1562 let (contents, destination, reply_path) = message;
1563 let _ = self.find_path_and_enqueue_onion_message(
1564 contents, destination, reply_path, format_args!("when sending OffersMessage")
1568 // Enqueue any initiating `CustomMessage`s to send.
1569 for message in self.custom_handler.release_pending_custom_messages() {
1570 #[cfg(not(c_bindings))]
1571 let PendingOnionMessage { contents, destination, reply_path } = message;
1573 let (contents, destination, reply_path) = message;
1574 let _ = self.find_path_and_enqueue_onion_message(
1575 contents, destination, reply_path, format_args!("when sending CustomMessage")
1579 self.message_recipients.lock().unwrap()
1580 .get_mut(&peer_node_id)
1581 .and_then(|buffer| buffer.dequeue_message())
1585 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
1587 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
1588 /// [`SimpleArcPeerManager`]. See their docs for more details.
1590 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1592 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
1593 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
1594 #[cfg(not(c_bindings))]
1595 pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
1599 Arc<SimpleArcChannelManager<M, T, F, L>>,
1600 Arc<DefaultMessageRouter<Arc<NetworkGraph<Arc<L>>>, Arc<L>, Arc<KeysManager>>>,
1601 Arc<SimpleArcChannelManager<M, T, F, L>>,
1602 IgnoringMessageHandler
1605 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
1606 /// [`SimpleRefPeerManager`]. See their docs for more details.
1608 /// This is not exported to bindings users as type aliases aren't supported in most languages.
1610 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
1611 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
1612 #[cfg(not(c_bindings))]
1613 pub type SimpleRefOnionMessenger<
1614 'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
1619 &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1620 &'j DefaultMessageRouter<&'g NetworkGraph<&'b L>, &'b L, &'a KeysManager>,
1621 &'i SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
1622 IgnoringMessageHandler
1625 /// Construct onion packet payloads and keys for sending an onion message along the given
1626 /// `unblinded_path` to the given `destination`.
1627 fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
1628 secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
1629 mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
1630 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), SendError> {
1631 let num_hops = unblinded_path.len() + destination.num_hops();
1632 let mut payloads = Vec::with_capacity(num_hops);
1633 let mut onion_packet_keys = Vec::with_capacity(num_hops);
1635 let (mut intro_node_id_blinding_pt, num_blinded_hops) = match &destination {
1636 Destination::Node(_) => (None, 0),
1637 Destination::BlindedPath(BlindedPath { introduction_node, blinding_point, blinded_hops }) => {
1638 let introduction_node_id = match introduction_node {
1639 IntroductionNode::NodeId(pubkey) => pubkey,
1640 IntroductionNode::DirectedShortChannelId(..) => {
1641 return Err(SendError::UnresolvedIntroductionNode);
1644 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len())
1647 let num_unblinded_hops = num_hops - num_blinded_hops;
1649 let mut unblinded_path_idx = 0;
1650 let mut blinded_path_idx = 0;
1651 let mut prev_control_tlvs_ss = None;
1652 let mut final_control_tlvs = None;
1653 utils::construct_keys_callback(secp_ctx, unblinded_path.iter(), Some(destination), session_priv,
1654 |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| {
1655 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
1656 if let Some(ss) = prev_control_tlvs_ss.take() {
1657 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
1659 next_hop: NextMessageHop::NodeId(unblinded_pk_opt.unwrap()),
1660 next_blinding_override: None,
1664 prev_control_tlvs_ss = Some(control_tlvs_ss);
1665 unblinded_path_idx += 1;
1666 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
1667 if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
1668 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
1669 next_hop: NextMessageHop::NodeId(intro_node_id),
1670 next_blinding_override: Some(blinding_pt),
1671 })), control_tlvs_ss));
1674 if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() {
1675 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
1677 blinded_path_idx += 1;
1678 } else if let Some(encrypted_payload) = enc_payload_opt {
1679 final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload));
1680 prev_control_tlvs_ss = Some(control_tlvs_ss);
1683 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
1684 onion_packet_keys.push(onion_utils::OnionKeys {
1686 shared_secret: onion_packet_ss,
1688 blinding_factor: [0; 32],
1694 ).map_err(|e| SendError::Secp256k1(e))?;
1696 if let Some(control_tlvs) = final_control_tlvs {
1697 payloads.push((Payload::Receive {
1699 reply_path: reply_path.take(),
1701 }, prev_control_tlvs_ss.unwrap()));
1703 payloads.push((Payload::Receive {
1704 control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }),
1705 reply_path: reply_path.take(),
1707 }, prev_control_tlvs_ss.unwrap()));
1710 Ok((payloads, onion_packet_keys))
1713 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
1714 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, ()> {
1716 // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
1717 // onion, but this should be used sparingly as it is reduces anonymity set, hence the
1718 // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
1719 let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
1720 let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
1721 SMALL_PACKET_HOP_DATA_LEN
1722 } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
1723 BIG_PACKET_HOP_DATA_LEN
1724 } else { return Err(()) };
1726 onion_utils::construct_onion_message_packet::<_, _>(
1727 payloads, onion_keys, prng_seed, hop_data_len)