pub(super) enum PendingHTLCRouting {
Forward {
onion_packet: msgs::OnionPacket,
- /// The SCID from the onion that we should forward to. This could be a "real" SCID, an
- /// outbound SCID alias, or a phantom node SCID.
+ /// The SCID from the onion that we should forward to. This could be a real SCID or a fake one
+ /// generated using `get_fake_scid` from the scid_utils::fake_scid module.
short_channel_id: u64, // This should be NonZero<u64> eventually when we bump MSRV
},
Receive {
Ok(PaymentId(buf))
}
}
+
+/// An identifier used to uniquely identify an intercepted HTLC to LDK.
+/// (C-not exported) as we just use [u8; 32] directly
+#[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
+pub struct InterceptId(pub [u8; 32]);
+
+impl Writeable for InterceptId {
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ self.0.write(w)
+ }
+}
+
+impl Readable for InterceptId {
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let buf: [u8; 32] = Readable::read(r)?;
+ Ok(InterceptId(buf))
+ }
+}
/// Tracks the inbound corresponding to an outbound HTLC
#[allow(clippy::derive_hash_xor_eq)] // Our Hash is faithful to the data, we just don't have SecretKey::hash
#[derive(Clone, PartialEq, Eq)]
// `total_consistency_lock`
// |
// |__`forward_htlcs`
+// | |
+// | |__`pending_intercepted_htlcs`
// |
// |__`pending_inbound_payments`
// | |
pub(super) forward_htlcs: Mutex<HashMap<u64, Vec<HTLCForwardInfo>>>,
#[cfg(not(test))]
forward_htlcs: Mutex<HashMap<u64, Vec<HTLCForwardInfo>>>,
+ /// Storage for HTLCs that have been intercepted and bubbled up to the user. We hold them here
+ /// until the user tells us what we should do with them.
+ ///
+ /// See `ChannelManager` struct-level documentation for lock order requirements.
+ pending_intercepted_htlcs: Mutex<HashMap<InterceptId, PendingAddHTLCInfo>>,
/// Map from payment hash to the payment data and any HTLCs which are to us and can be
/// failed/claimed by the user.
pending_outbound_payments: Mutex::new(HashMap::new()),
forward_htlcs: Mutex::new(HashMap::new()),
claimable_htlcs: Mutex::new(HashMap::new()),
+ pending_intercepted_htlcs: Mutex::new(HashMap::new()),
id_to_peer: Mutex::new(HashMap::new()),
short_to_chan_info: FairRwLock::new(HashMap::new()),
let forwarding_id_opt = match id_option {
None => { // unknown_next_peer
// Note that this is likely a timing oracle for detecting whether an scid is a
- // phantom.
- if fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, *short_channel_id, &self.genesis_hash) {
+ // phantom or an intercept.
+ if (self.default_configuration.accept_intercept_htlcs &&
+ fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, *short_channel_id, &self.genesis_hash)) ||
+ fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, *short_channel_id, &self.genesis_hash)
+ {
None
} else {
break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
Ok(())
}
+ /// Attempts to forward an intercepted HTLC over the provided channel id and with the provided
+ /// amount to forward. Should only be called in response to an [`HTLCIntercepted`] event.
+ ///
+ /// Intercepted HTLCs can be useful for Lightning Service Providers (LSPs) to open a just-in-time
+ /// channel to a receiving node if the node lacks sufficient inbound liquidity.
+ ///
+ /// To make use of intercepted HTLCs, set [`UserConfig::accept_intercept_htlcs`] and use
+ /// [`ChannelManager::get_intercept_scid`] to generate short channel id(s) to put in the
+ /// receiver's invoice route hints. These route hints will signal to LDK to generate an
+ /// [`HTLCIntercepted`] event when it receives the forwarded HTLC, and this method or
+ /// [`ChannelManager::fail_intercepted_htlc`] MUST be called in response to the event.
+ ///
+ /// Note that LDK does not enforce fee requirements in `amt_to_forward_msat`, and will not stop
+ /// you from forwarding more than you received.
+ ///
+ /// Errors if the event was not handled in time, in which case the HTLC was automatically failed
+ /// backwards.
+ ///
+ /// [`UserConfig::accept_intercept_htlcs`]: crate::util::config::UserConfig::accept_intercept_htlcs
+ /// [`HTLCIntercepted`]: events::Event::HTLCIntercepted
+ // TODO: when we move to deciding the best outbound channel at forward time, only take
+ // `next_node_id` and not `next_hop_channel_id`
+ pub fn forward_intercepted_htlc(&self, intercept_id: InterceptId, next_hop_channel_id: &[u8; 32], _next_node_id: PublicKey, amt_to_forward_msat: u64) -> Result<(), APIError> {
+ let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
+
+ let next_hop_scid = match self.channel_state.lock().unwrap().by_id.get(next_hop_channel_id) {
+ Some(chan) => {
+ if !chan.is_usable() {
+ return Err(APIError::APIMisuseError {
+ err: format!("Channel with id {:?} not fully established", next_hop_channel_id)
+ })
+ }
+ chan.get_short_channel_id().unwrap_or(chan.outbound_scid_alias())
+ },
+ None => return Err(APIError::APIMisuseError {
+ err: format!("Channel with id {:?} not found", next_hop_channel_id)
+ })
+ };
+
+ let payment = self.pending_intercepted_htlcs.lock().unwrap().remove(&intercept_id)
+ .ok_or_else(|| APIError::APIMisuseError {
+ err: format!("Payment with intercept id {:?} not found", intercept_id.0)
+ })?;
+
+ let routing = match payment.forward_info.routing {
+ PendingHTLCRouting::Forward { onion_packet, .. } => {
+ PendingHTLCRouting::Forward { onion_packet, short_channel_id: next_hop_scid }
+ },
+ _ => unreachable!() // Only `PendingHTLCRouting::Forward`s are intercepted
+ };
+ let pending_htlc_info = PendingHTLCInfo {
+ outgoing_amt_msat: amt_to_forward_msat, routing, ..payment.forward_info
+ };
+
+ let mut per_source_pending_forward = [(
+ payment.prev_short_channel_id,
+ payment.prev_funding_outpoint,
+ payment.prev_user_channel_id,
+ vec![(pending_htlc_info, payment.prev_htlc_id)]
+ )];
+ self.forward_htlcs(&mut per_source_pending_forward);
+ Ok(())
+ }
+
+ /// Fails the intercepted HTLC indicated by intercept_id. Should only be called in response to
+ /// an [`HTLCIntercepted`] event. See [`ChannelManager::forward_intercepted_htlc`].
+ ///
+ /// Errors if the event was not handled in time, in which case the HTLC was automatically failed
+ /// backwards.
+ ///
+ /// [`HTLCIntercepted`]: events::Event::HTLCIntercepted
+ pub fn fail_intercepted_htlc(&self, intercept_id: InterceptId) -> Result<(), APIError> {
+ let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
+
+ let payment = self.pending_intercepted_htlcs.lock().unwrap().remove(&intercept_id)
+ .ok_or_else(|| APIError::APIMisuseError {
+ err: format!("Payment with InterceptId {:?} not found", intercept_id)
+ })?;
+
+ if let PendingHTLCRouting::Forward { short_channel_id, .. } = payment.forward_info.routing {
+ let htlc_source = HTLCSource::PreviousHopData(HTLCPreviousHopData {
+ short_channel_id: payment.prev_short_channel_id,
+ outpoint: payment.prev_funding_outpoint,
+ htlc_id: payment.prev_htlc_id,
+ incoming_packet_shared_secret: payment.forward_info.incoming_shared_secret,
+ phantom_shared_secret: None,
+ });
+
+ let failure_reason = HTLCFailReason::Reason { failure_code: 0x4000 | 10, data: Vec::new() };
+ let destination = HTLCDestination::UnknownNextHop { requested_forward_scid: short_channel_id };
+ self.fail_htlc_backwards_internal(htlc_source, &payment.forward_info.payment_hash, failure_reason, destination);
+ } else { unreachable!() } // Only `PendingHTLCRouting::Forward`s are intercepted
+
+ Ok(())
+ }
+
/// Processes HTLCs which are pending waiting on random forward delay.
///
/// Should only really ever be called in response to a PendingHTLCsForwardable event.
fn forward_htlcs(&self, per_source_pending_forwards: &mut [(u64, OutPoint, u128, Vec<(PendingHTLCInfo, u64)>)]) {
for &mut (prev_short_channel_id, prev_funding_outpoint, prev_user_channel_id, ref mut pending_forwards) in per_source_pending_forwards {
let mut forward_event = None;
+ let mut new_intercept_events = Vec::new();
+ let mut failed_intercept_forwards = Vec::new();
if !pending_forwards.is_empty() {
- let mut forward_htlcs = self.forward_htlcs.lock().unwrap();
- if forward_htlcs.is_empty() {
- forward_event = Some(Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS))
- }
for (forward_info, prev_htlc_id) in pending_forwards.drain(..) {
- match forward_htlcs.entry(match forward_info.routing {
- PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
- PendingHTLCRouting::Receive { .. } => 0,
- PendingHTLCRouting::ReceiveKeysend { .. } => 0,
- }) {
+ let scid = match forward_info.routing {
+ PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
+ PendingHTLCRouting::Receive { .. } => 0,
+ PendingHTLCRouting::ReceiveKeysend { .. } => 0,
+ };
+ // Pull this now to avoid introducing a lock order with `forward_htlcs`.
+ let is_our_scid = self.short_to_chan_info.read().unwrap().contains_key(&scid);
+
+ let mut forward_htlcs = self.forward_htlcs.lock().unwrap();
+ let forward_htlcs_empty = forward_htlcs.is_empty();
+ match forward_htlcs.entry(scid) {
hash_map::Entry::Occupied(mut entry) => {
entry.get_mut().push(HTLCForwardInfo::AddHTLC(PendingAddHTLCInfo {
prev_short_channel_id, prev_funding_outpoint, prev_htlc_id, prev_user_channel_id, forward_info }));
},
hash_map::Entry::Vacant(entry) => {
- entry.insert(vec!(HTLCForwardInfo::AddHTLC(PendingAddHTLCInfo {
- prev_short_channel_id, prev_funding_outpoint, prev_htlc_id, prev_user_channel_id, forward_info })));
+ if !is_our_scid && forward_info.incoming_amt_msat.is_some() &&
+ fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, scid, &self.genesis_hash)
+ {
+ let intercept_id = InterceptId(Sha256::hash(&forward_info.incoming_shared_secret).into_inner());
+ let mut pending_intercepts = self.pending_intercepted_htlcs.lock().unwrap();
+ match pending_intercepts.entry(intercept_id) {
+ hash_map::Entry::Vacant(entry) => {
+ new_intercept_events.push(events::Event::HTLCIntercepted {
+ requested_next_hop_scid: scid,
+ payment_hash: forward_info.payment_hash,
+ inbound_amount_msat: forward_info.incoming_amt_msat.unwrap(),
+ expected_outbound_amount_msat: forward_info.outgoing_amt_msat,
+ intercept_id
+ });
+ entry.insert(PendingAddHTLCInfo {
+ prev_short_channel_id, prev_funding_outpoint, prev_htlc_id, prev_user_channel_id, forward_info });
+ },
+ hash_map::Entry::Occupied(_) => {
+ log_info!(self.logger, "Failed to forward incoming HTLC: detected duplicate intercepted payment over short channel id {}", scid);
+ let htlc_source = HTLCSource::PreviousHopData(HTLCPreviousHopData {
+ short_channel_id: prev_short_channel_id,
+ outpoint: prev_funding_outpoint,
+ htlc_id: prev_htlc_id,
+ incoming_packet_shared_secret: forward_info.incoming_shared_secret,
+ phantom_shared_secret: None,
+ });
+
+ failed_intercept_forwards.push((htlc_source, forward_info.payment_hash,
+ HTLCFailReason::Reason { failure_code: 0x4000 | 10, data: Vec::new() },
+ HTLCDestination::InvalidForward { requested_forward_scid: scid },
+ ));
+ }
+ }
+ } else {
+ // We don't want to generate a PendingHTLCsForwardable event if only intercepted
+ // payments are being processed.
+ if forward_htlcs_empty {
+ forward_event = Some(Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS));
+ }
+ entry.insert(vec!(HTLCForwardInfo::AddHTLC(PendingAddHTLCInfo {
+ prev_short_channel_id, prev_funding_outpoint, prev_htlc_id, prev_user_channel_id, forward_info })));
+ }
}
}
}
}
+
+ for (htlc_source, payment_hash, failure_reason, destination) in failed_intercept_forwards.drain(..) {
+ self.fail_htlc_backwards_internal(htlc_source, &payment_hash, failure_reason, destination);
+ }
+
+ if !new_intercept_events.is_empty() {
+ let mut events = self.pending_events.lock().unwrap();
+ events.append(&mut new_intercept_events);
+ }
+
match forward_event {
Some(time) => {
let mut pending_events = self.pending_events.lock().unwrap();
}
}
+ /// Gets a fake short channel id for use in receiving intercepted payments. These fake scids are
+ /// used when constructing the route hints for HTLCs intended to be intercepted. See
+ /// [`ChannelManager::forward_intercepted_htlc`].
+ ///
+ /// Note that this method is not guaranteed to return unique values, you may need to call it a few
+ /// times to get a unique scid.
+ pub fn get_intercept_scid(&self) -> u64 {
+ let best_block_height = self.best_block.read().unwrap().height();
+ let short_to_chan_info = self.short_to_chan_info.read().unwrap();
+ loop {
+ let scid_candidate = fake_scid::Namespace::Intercept.get_fake_scid(best_block_height, &self.genesis_hash, &self.fake_scid_rand_bytes, &self.keys_manager);
+ // Ensure the generated scid doesn't conflict with a real channel.
+ if short_to_chan_info.contains_key(&scid_candidate) { continue }
+ return scid_candidate
+ }
+ }
+
/// Gets inflight HTLC information by processing pending outbound payments that are in
/// our channels. May be used during pathfinding to account for in-use channel liquidity.
pub fn compute_inflight_htlcs(&self) -> InFlightHtlcs {
if height >= htlc.cltv_expiry - HTLC_FAIL_BACK_BUFFER {
let mut htlc_msat_height_data = byte_utils::be64_to_array(htlc.value).to_vec();
htlc_msat_height_data.extend_from_slice(&byte_utils::be32_to_array(height));
-
timed_out_htlcs.push((HTLCSource::PreviousHopData(htlc.prev_hop.clone()), payment_hash.clone(), HTLCFailReason::Reason {
failure_code: 0x4000 | 15,
data: htlc_msat_height_data
});
!htlcs.is_empty() // Only retain this entry if htlcs has at least one entry.
});
+
+ let mut intercepted_htlcs = self.pending_intercepted_htlcs.lock().unwrap();
+ intercepted_htlcs.retain(|_, htlc| {
+ if height >= htlc.forward_info.outgoing_cltv_value - HTLC_FAIL_BACK_BUFFER {
+ let prev_hop_data = HTLCSource::PreviousHopData(HTLCPreviousHopData {
+ short_channel_id: htlc.prev_short_channel_id,
+ htlc_id: htlc.prev_htlc_id,
+ incoming_packet_shared_secret: htlc.forward_info.incoming_shared_secret,
+ phantom_shared_secret: None,
+ outpoint: htlc.prev_funding_outpoint,
+ });
+
+ let requested_forward_scid /* intercept scid */ = match htlc.forward_info.routing {
+ PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
+ _ => unreachable!(),
+ };
+ timed_out_htlcs.push((prev_hop_data, htlc.forward_info.payment_hash,
+ HTLCFailReason::Reason { failure_code: 0x2000 | 2, data: Vec::new() },
+ HTLCDestination::InvalidForward { requested_forward_scid }));
+ log_trace!(self.logger, "Timing out intercepted HTLC with requested forward scid {}", requested_forward_scid);
+ false
+ } else { true }
+ });
}
self.handle_init_event_channel_failures(failed_channels);
_ => {},
}
}
+
+ let mut pending_intercepted_htlcs = None;
+ let our_pending_intercepts = self.pending_intercepted_htlcs.lock().unwrap();
+ if our_pending_intercepts.len() != 0 {
+ pending_intercepted_htlcs = Some(our_pending_intercepts);
+ }
write_tlv_fields!(writer, {
(1, pending_outbound_payments_no_retry, required),
+ (2, pending_intercepted_htlcs, option),
(3, pending_outbound_payments, required),
(5, self.our_network_pubkey, required),
(7, self.fake_scid_rand_bytes, required),
// pending_outbound_payments_no_retry is for compatibility with 0.0.101 clients.
let mut pending_outbound_payments_no_retry: Option<HashMap<PaymentId, HashSet<[u8; 32]>>> = None;
let mut pending_outbound_payments = None;
+ let mut pending_intercepted_htlcs: Option<HashMap<InterceptId, PendingAddHTLCInfo>> = Some(HashMap::new());
let mut received_network_pubkey: Option<PublicKey> = None;
let mut fake_scid_rand_bytes: Option<[u8; 32]> = None;
let mut probing_cookie_secret: Option<[u8; 32]> = None;
let mut claimable_htlc_purposes = None;
read_tlv_fields!(reader, {
(1, pending_outbound_payments_no_retry, option),
+ (2, pending_intercepted_htlcs, option),
(3, pending_outbound_payments, option),
(5, received_network_pubkey, option),
(7, fake_scid_rand_bytes, option),
inbound_payment_key: expanded_inbound_key,
pending_inbound_payments: Mutex::new(pending_inbound_payments),
pending_outbound_payments: Mutex::new(pending_outbound_payments.unwrap()),
+ pending_intercepted_htlcs: Mutex::new(pending_intercepted_htlcs.unwrap()),
forward_htlcs: Mutex::new(forward_htlcs),
claimable_htlcs: Mutex::new(claimable_htlcs),
projects / rust-lightning / blobdiff