Merge pull request #2534 from tnull/2023-08-upstream-preflight-probing
[rust-lightning] / lightning / src / ln / channelmanager.rs
index 90451d59d66d635821ffbe3ce32790d471290c6c..0cadbd41a29d21ccb99de1e0d7bf84319e33971c 100644 (file)
@@ -77,7 +77,7 @@ use core::time::Duration;
 use core::ops::Deref;
 
 // Re-export this for use in the public API.
-pub use crate::ln::outbound_payment::{PaymentSendFailure, Retry, RetryableSendFailure, RecipientOnionFields};
+pub use crate::ln::outbound_payment::{PaymentSendFailure, ProbeSendFailure, Retry, RetryableSendFailure, RecipientOnionFields};
 use crate::ln::script::ShutdownScript;
 
 // We hold various information about HTLC relay in the HTLC objects in Channel itself:
@@ -839,33 +839,46 @@ pub type SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L> =
                &'g L
        >;
 
-macro_rules! define_test_pub_trait { ($vis: vis) => {
-/// A trivial trait which describes any [`ChannelManager`] used in testing.
-$vis trait AChannelManager {
+/// A trivial trait which describes any [`ChannelManager`].
+pub trait AChannelManager {
+       /// A type implementing [`chain::Watch`].
        type Watch: chain::Watch<Self::Signer> + ?Sized;
+       /// A type that may be dereferenced to [`Self::Watch`].
        type M: Deref<Target = Self::Watch>;
+       /// A type implementing [`BroadcasterInterface`].
        type Broadcaster: BroadcasterInterface + ?Sized;
+       /// A type that may be dereferenced to [`Self::Broadcaster`].
        type T: Deref<Target = Self::Broadcaster>;
+       /// A type implementing [`EntropySource`].
        type EntropySource: EntropySource + ?Sized;
+       /// A type that may be dereferenced to [`Self::EntropySource`].
        type ES: Deref<Target = Self::EntropySource>;
+       /// A type implementing [`NodeSigner`].
        type NodeSigner: NodeSigner + ?Sized;
+       /// A type that may be dereferenced to [`Self::NodeSigner`].
        type NS: Deref<Target = Self::NodeSigner>;
+       /// A type implementing [`WriteableEcdsaChannelSigner`].
        type Signer: WriteableEcdsaChannelSigner + Sized;
+       /// A type implementing [`SignerProvider`] for [`Self::Signer`].
        type SignerProvider: SignerProvider<Signer = Self::Signer> + ?Sized;
+       /// A type that may be dereferenced to [`Self::SignerProvider`].
        type SP: Deref<Target = Self::SignerProvider>;
+       /// A type implementing [`FeeEstimator`].
        type FeeEstimator: FeeEstimator + ?Sized;
+       /// A type that may be dereferenced to [`Self::FeeEstimator`].
        type F: Deref<Target = Self::FeeEstimator>;
+       /// A type implementing [`Router`].
        type Router: Router + ?Sized;
+       /// A type that may be dereferenced to [`Self::Router`].
        type R: Deref<Target = Self::Router>;
+       /// A type implementing [`Logger`].
        type Logger: Logger + ?Sized;
+       /// A type that may be dereferenced to [`Self::Logger`].
        type L: Deref<Target = Self::Logger>;
+       /// Returns a reference to the actual [`ChannelManager`] object.
        fn get_cm(&self) -> &ChannelManager<Self::M, Self::T, Self::ES, Self::NS, Self::SP, Self::F, Self::R, Self::L>;
 }
-} }
-#[cfg(any(test, feature = "_test_utils"))]
-define_test_pub_trait!(pub);
-#[cfg(not(any(test, feature = "_test_utils")))]
-define_test_pub_trait!(pub(crate));
+
 impl<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref> AChannelManager
 for ChannelManager<M, T, ES, NS, SP, F, R, L>
 where
@@ -3546,6 +3559,116 @@ where
                outbound_payment::payment_is_probe(payment_hash, payment_id, self.probing_cookie_secret)
        }
 
+       /// Sends payment probes over all paths of a route that would be used to pay the given
+       /// amount to the given `node_id`.
+       ///
+       /// See [`ChannelManager::send_preflight_probes`] for more information.
+       pub fn send_spontaneous_preflight_probes(
+               &self, node_id: PublicKey, amount_msat: u64, final_cltv_expiry_delta: u32, 
+               liquidity_limit_multiplier: Option<u64>,
+       ) -> Result<Vec<(PaymentHash, PaymentId)>, ProbeSendFailure> {
+               let payment_params =
+                       PaymentParameters::from_node_id(node_id, final_cltv_expiry_delta);
+
+               let route_params = RouteParameters { payment_params, final_value_msat: amount_msat };
+
+               self.send_preflight_probes(route_params, liquidity_limit_multiplier)
+       }
+
+       /// Sends payment probes over all paths of a route that would be used to pay a route found
+       /// according to the given [`RouteParameters`].
+       ///
+       /// This may be used to send "pre-flight" probes, i.e., to train our scorer before conducting
+       /// the actual payment. Note this is only useful if there likely is sufficient time for the
+       /// probe to settle before sending out the actual payment, e.g., when waiting for user
+       /// confirmation in a wallet UI.
+       ///
+       /// Otherwise, there is a chance the probe could take up some liquidity needed to complete the
+       /// actual payment. Users should therefore be cautious and might avoid sending probes if
+       /// liquidity is scarce and/or they don't expect the probe to return before they send the
+       /// payment. To mitigate this issue, channels with available liquidity less than the required
+       /// amount times the given `liquidity_limit_multiplier` won't be used to send pre-flight
+       /// probes. If `None` is given as `liquidity_limit_multiplier`, it defaults to `3`.
+       pub fn send_preflight_probes(
+               &self, route_params: RouteParameters, liquidity_limit_multiplier: Option<u64>,
+       ) -> Result<Vec<(PaymentHash, PaymentId)>, ProbeSendFailure> {
+               let liquidity_limit_multiplier = liquidity_limit_multiplier.unwrap_or(3);
+
+               let payer = self.get_our_node_id();
+               let usable_channels = self.list_usable_channels();
+               let first_hops = usable_channels.iter().collect::<Vec<_>>();
+               let inflight_htlcs = self.compute_inflight_htlcs();
+
+               let route = self
+                       .router
+                       .find_route(&payer, &route_params, Some(&first_hops), inflight_htlcs)
+                       .map_err(|e| {
+                               log_error!(self.logger, "Failed to find path for payment probe: {:?}", e);
+                               ProbeSendFailure::RouteNotFound
+                       })?;
+
+               let mut used_liquidity_map = HashMap::with_capacity(first_hops.len());
+
+               let mut res = Vec::new();
+
+               for mut path in route.paths {
+                       // If the last hop is probably an unannounced channel we refrain from probing all the
+                       // way through to the end and instead probe up to the second-to-last channel.
+                       while let Some(last_path_hop) = path.hops.last() {
+                               if last_path_hop.maybe_announced_channel {
+                                       // We found a potentially announced last hop.
+                                       break;
+                               } else {
+                                       // Drop the last hop, as it's likely unannounced.
+                                       log_debug!(
+                                               self.logger,
+                                               "Avoided sending payment probe all the way to last hop {} as it is likely unannounced.",
+                                               last_path_hop.short_channel_id
+                                       );
+                                       let final_value_msat = path.final_value_msat();
+                                       path.hops.pop();
+                                       if let Some(new_last) = path.hops.last_mut() {
+                                               new_last.fee_msat += final_value_msat;
+                                       }
+                               }
+                       }
+
+                       if path.hops.len() < 2 {
+                               log_debug!(
+                                       self.logger,
+                                       "Skipped sending payment probe over path with less than two hops."
+                               );
+                               continue;
+                       }
+
+                       if let Some(first_path_hop) = path.hops.first() {
+                               if let Some(first_hop) = first_hops.iter().find(|h| {
+                                       h.get_outbound_payment_scid() == Some(first_path_hop.short_channel_id)
+                               }) {
+                                       let path_value = path.final_value_msat() + path.fee_msat();
+                                       let used_liquidity =
+                                               used_liquidity_map.entry(first_path_hop.short_channel_id).or_insert(0);
+
+                                       if first_hop.next_outbound_htlc_limit_msat
+                                               < (*used_liquidity + path_value) * liquidity_limit_multiplier
+                                       {
+                                               log_debug!(self.logger, "Skipped sending payment probe to avoid putting channel {} under the liquidity limit.", first_path_hop.short_channel_id);
+                                               continue;
+                                       } else {
+                                               *used_liquidity += path_value;
+                                       }
+                               }
+                       }
+
+                       res.push(self.send_probe(path).map_err(|e| {
+                               log_error!(self.logger, "Failed to send pre-flight probe: {:?}", e);
+                               ProbeSendFailure::SendingFailed(e)
+                       })?);
+               }
+
+               Ok(res)
+       }
+
        /// Handles the generation of a funding transaction, optionally (for tests) with a function
        /// which checks the correctness of the funding transaction given the associated channel.
        fn funding_transaction_generated_intern<FundingOutput: Fn(&OutboundV1Channel<SP>, &Transaction) -> Result<OutPoint, APIError>>(