LSPS2: Prune expired buy requests on disconnection

.. we clean up any pending buy requests that hit their `valid_until`
time when the counterparty disconnects.

lightning-liquidity/src/lsps2/service.rs

@@ -15,7 +15,9 @@ use crate::lsps0::ser::{
 };
 use crate::lsps2::event::LSPS2ServiceEvent;
 use crate::lsps2::payment_queue::{InterceptedHTLC, PaymentQueue};
-use crate::lsps2::utils::{compute_opening_fee, is_valid_opening_fee_params};
+use crate::lsps2::utils::{
+	compute_opening_fee, is_expired_opening_fee_params, is_valid_opening_fee_params,
+};
 use crate::message_queue::MessageQueue;
 use crate::prelude::{new_hash_map, HashMap, String, ToString, Vec};
 use crate::sync::{Arc, Mutex, RwLock};
@@ -477,8 +479,15 @@ impl PeerState {
 	}
 
 	fn peer_disconnected(&mut self) {
-		// Clean any pending `get_info` requests.
-		self.pending_requests.retain(|_, entry| !matches!(entry, LSPS2Request::GetInfo(_)));
+		self.pending_requests.retain(|_, entry| {
+			match entry {
+				LSPS2Request::GetInfo(_) => false,
+				LSPS2Request::Buy(request) => {
+					// Prune any expired buy requests.
+					!is_expired_opening_fee_params(&request.opening_fee_params)
+				},
+			}
+		});
 	}
 }
 

lightning-liquidity/src/lsps2/utils.rs

@@ -14,23 +14,9 @@ use std::time::{SystemTime, UNIX_EPOCH};
 pub fn is_valid_opening_fee_params(
 	fee_params: &OpeningFeeParams, promise_secret: &[u8; 32],
 ) -> bool {
-	#[cfg(feature = "std")]
-	{
-		// TODO: We need to find a way to check expiry times in no-std builds.
-		let seconds_since_epoch = SystemTime::now()
-			.duration_since(UNIX_EPOCH)
-			.expect("system clock to be ahead of the unix epoch")
-			.as_secs();
-		let valid_until_seconds_since_epoch = fee_params
-			.valid_until
-			.timestamp()
-			.try_into()
-			.expect("expiration to be ahead of unix epoch");
-		if seconds_since_epoch > valid_until_seconds_since_epoch {
-			return false;
-		}
+	if is_expired_opening_fee_params(fee_params) {
+		return false;
 	}
-
 	let mut hmac = HmacEngine::<Sha256>::new(promise_secret);
 	hmac.input(&fee_params.min_fee_msat.to_be_bytes());
 	hmac.input(&fee_params.proportional.to_be_bytes());
@@ -44,6 +30,28 @@ pub fn is_valid_opening_fee_params(
 	promise == fee_params.promise
 }
 
+/// Determines if the given parameters are expired, or still valid.
+pub fn is_expired_opening_fee_params(fee_params: &OpeningFeeParams) -> bool {
+	#[cfg(feature = "std")]
+	{
+		let seconds_since_epoch = SystemTime::now()
+			.duration_since(UNIX_EPOCH)
+			.expect("system clock to be ahead of the unix epoch")
+			.as_secs();
+		let valid_until_seconds_since_epoch = fee_params
+			.valid_until
+			.timestamp()
+			.try_into()
+			.expect("expiration to be ahead of unix epoch");
+		seconds_since_epoch > valid_until_seconds_since_epoch
+	}
+	#[cfg(not(feature = "std"))]
+	{
+		// TODO: We need to find a way to check expiry times in no-std builds.
+		false
+	}
+}
+
 /// Computes the opening fee given a payment size and the fee parameters.
 ///
 /// Returns [`Option::None`] when the computation overflows.