Make fuzz targets deterministic

Gate all SystemTime::now() and Instant::now() calls in production code
with #[cfg(all(feature = "std", not(fuzzing)))] so that fuzz targets
produce consistent results regardless of wall-clock time. For each
location, the existing no-std fallback (highest_seen_timestamp, None,
or a constant) is reused under fuzzing.

Also force deterministic hashing when the fuzzing cfg is active,
rather than requiring the LDK_TEST_DETERMINISTIC_HASHES env var.

AI tools were used in preparing this commit.

Author: joostjager

lightning/src/ln/channel.rs

@@ -16717,10 +16717,10 @@ impl<'a, 'b, 'c, ES: EntropySource, SP: SignerProvider>
 }
 
 fn duration_since_epoch() -> Option<Duration> {
-	#[cfg(not(feature = "std"))]
+	#[cfg(any(not(feature = "std"), fuzzing))]
 	let now = None;
 
-	#[cfg(feature = "std")]
+	#[cfg(all(feature = "std", not(fuzzing)))]
 	let now = Some(
 		std::time::SystemTime::now()
 			.duration_since(std::time::SystemTime::UNIX_EPOCH)

lightning/src/ln/channelmanager.rs

@@ -8936,11 +8936,11 @@ impl<
 				let _ = self.handle_error(err, counterparty_node_id);
 			}
 
-			#[cfg(feature = "std")]
+			#[cfg(all(feature = "std", not(fuzzing)))]
 			let duration_since_epoch = std::time::SystemTime::now()
 				.duration_since(std::time::SystemTime::UNIX_EPOCH)
 				.expect("SystemTime::now() should come after SystemTime::UNIX_EPOCH");
-			#[cfg(not(feature = "std"))]
+			#[cfg(any(not(feature = "std"), fuzzing))]
 			let duration_since_epoch = Duration::from_secs(
 				self.highest_seen_timestamp.load(Ordering::Acquire).saturating_sub(7200) as u64,
 			);
@@ -14129,7 +14129,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 		let currency =
 			Network::from_chain_hash(self.chain_hash).map(Into::into).unwrap_or(Currency::Bitcoin);
 
-		#[cfg(feature = "std")]
+		#[cfg(all(feature = "std", not(fuzzing)))]
 		let duration_since_epoch = {
 			use std::time::SystemTime;
 			SystemTime::now().duration_since(SystemTime::UNIX_EPOCH)
@@ -14139,7 +14139,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 		// This may be up to 2 hours in the future because of bitcoin's block time rule or about
 		// 10-30 minutes in the past if a block hasn't been found recently. This should be fine as
 		// the default invoice expiration is 2 hours, though shorter expirations may be problematic.
-		#[cfg(not(feature = "std"))]
+		#[cfg(any(not(feature = "std"), fuzzing))]
 		let duration_since_epoch =
 			Duration::from_secs(self.highest_seen_timestamp.load(Ordering::Acquire) as u64);
 
@@ -14996,9 +14996,9 @@ impl<
 	}
 
 	pub(super) fn duration_since_epoch(&self) -> Duration {
-		#[cfg(not(feature = "std"))]
+		#[cfg(any(not(feature = "std"), fuzzing))]
 		let now = Duration::from_secs(self.highest_seen_timestamp.load(Ordering::Acquire) as u64);
-		#[cfg(feature = "std")]
+		#[cfg(all(feature = "std", not(fuzzing)))]
 		let now = std::time::SystemTime::now()
 			.duration_since(std::time::SystemTime::UNIX_EPOCH)
 			.expect("SystemTime::now() should come after SystemTime::UNIX_EPOCH");

lightning/src/ln/outbound_payment.rs

@@ -446,14 +446,16 @@ impl Retry {
 			(Retry::Attempts(max_retry_count), PaymentAttempts { count, .. }) => {
 				max_retry_count > count
 			},
-			#[cfg(feature = "std")]
+			#[cfg(all(feature = "std", not(fuzzing)))]
 			(Retry::Timeout(max_duration), PaymentAttempts { first_attempted_at, .. }) =>
 				*max_duration >= Instant::now().duration_since(*first_attempted_at),
+			#[cfg(all(feature = "std", fuzzing))]
+			(Retry::Timeout(_), _) => true,
 		}
 	}
 }
 
-#[cfg(feature = "std")]
+#[cfg(all(feature = "std", not(fuzzing)))]
 #[rustfmt::skip]
 pub(super) fn has_expired(route_params: &RouteParameters) -> bool {
 	if let Some(expiry_time) = route_params.payment_params.expiry_time {
@@ -464,32 +466,38 @@ pub(super) fn has_expired(route_params: &RouteParameters) -> bool {
 	false
 }
 
+#[cfg(all(feature = "std", fuzzing))]
+#[rustfmt::skip]
+pub(super) fn has_expired(_route_params: &RouteParameters) -> bool {
+	false
+}
+
 /// Storing minimal payment attempts information required for determining if a outbound payment can
 /// be retried.
 pub(crate) struct PaymentAttempts {
 	/// This count will be incremented only after the result of the attempt is known. When it's 0,
 	/// it means the result of the first attempt is not known yet.
 	pub(crate) count: u32,
 	/// This field is only used when retry is `Retry::Timeout` which is only build with feature std
-	#[cfg(feature = "std")]
+	#[cfg(all(feature = "std", not(fuzzing)))]
 	first_attempted_at: Instant,
 }
 
 impl PaymentAttempts {
 	pub(crate) fn new() -> Self {
 		PaymentAttempts {
 			count: 0,
-			#[cfg(feature = "std")]
+			#[cfg(all(feature = "std", not(fuzzing)))]
 			first_attempted_at: Instant::now(),
 		}
 	}
 }
 
 impl Display for PaymentAttempts {
 	fn fmt(&self, f: &mut Formatter) -> Result<(), fmt::Error> {
-		#[cfg(not(feature = "std"))]
+		#[cfg(any(not(feature = "std"), fuzzing))]
 		return write!(f, "attempts: {}", self.count);
-		#[cfg(feature = "std")]
+		#[cfg(all(feature = "std", not(fuzzing)))]
 		return write!(
 			f,
 			"attempts: {}, duration: {}s",

lightning/src/ln/peer_handler.rs

@@ -2327,7 +2327,7 @@ impl<
 
 				#[allow(unused_mut)]
 				let mut should_do_full_sync = true;
-				#[cfg(feature = "std")]
+				#[cfg(all(feature = "std", not(fuzzing)))]
 				{
 					// Forward ad-hoc gossip if the timestamp range is less than six hours ago.
 					// Otherwise, do a full sync.

lightning/src/offers/flow.rs

@@ -183,9 +183,9 @@ impl<MR: MessageRouter, L: Logger> OffersMessageFlow<MR, L> {
 	}
 
 	fn duration_since_epoch(&self) -> Duration {
-		#[cfg(not(feature = "std"))]
+		#[cfg(any(not(feature = "std"), fuzzing))]
 		let now = Duration::from_secs(self.highest_seen_timestamp.load(Ordering::Acquire) as u64);
-		#[cfg(feature = "std")]
+		#[cfg(all(feature = "std", not(fuzzing)))]
 		let now = std::time::SystemTime::now()
 			.duration_since(std::time::SystemTime::UNIX_EPOCH)
 			.expect("SystemTime::now() should come after SystemTime::UNIX_EPOCH");
@@ -942,17 +942,17 @@ impl<MR: MessageRouter, L: Logger> OffersMessageFlow<MR, L> {
 			)
 			.map_err(|_| Bolt12SemanticError::MissingPaths)?;
 
-		#[cfg(feature = "std")]
+		#[cfg(all(feature = "std", not(fuzzing)))]
 		let builder = refund.respond_using_derived_keys(
 			payment_paths,
 			payment_hash,
 			expanded_key,
 			entropy,
 		)?;
 
-		#[cfg(not(feature = "std"))]
+		#[cfg(any(not(feature = "std"), fuzzing))]
 		let created_at = Duration::from_secs(self.highest_seen_timestamp.load(Ordering::Acquire) as u64);
-		#[cfg(not(feature = "std"))]
+		#[cfg(any(not(feature = "std"), fuzzing))]
 		let builder = refund.respond_using_derived_keys_no_std(
 			payment_paths,
 			payment_hash,
@@ -1008,9 +1008,9 @@ impl<MR: MessageRouter, L: Logger> OffersMessageFlow<MR, L> {
 			)
 			.map_err(|_| Bolt12SemanticError::MissingPaths)?;
 
-		#[cfg(feature = "std")]
+		#[cfg(all(feature = "std", not(fuzzing)))]
 		let builder = invoice_request.respond_using_derived_keys(payment_paths, payment_hash);
-		#[cfg(not(feature = "std"))]
+		#[cfg(any(not(feature = "std"), fuzzing))]
 		let builder = invoice_request.respond_using_derived_keys_no_std(
 			payment_paths,
 			payment_hash,
@@ -1067,9 +1067,9 @@ impl<MR: MessageRouter, L: Logger> OffersMessageFlow<MR, L> {
 			)
 			.map_err(|_| Bolt12SemanticError::MissingPaths)?;
 
-		#[cfg(feature = "std")]
+		#[cfg(all(feature = "std", not(fuzzing)))]
 		let builder = invoice_request.respond_with(payment_paths, payment_hash);
-		#[cfg(not(feature = "std"))]
+		#[cfg(any(not(feature = "std"), fuzzing))]
 		let builder = invoice_request.respond_with_no_std(
 			payment_paths,
 			payment_hash,

lightning/src/onion_message/dns_resolution.rs

@@ -501,7 +501,7 @@ impl OMNameResolver {
 			if let Ok(validated_rrs) = validated_rrs {
 				#[allow(unused_assignments, unused_mut)]
 				let mut time = self.latest_block_time.load(Ordering::Acquire) as u64;
-				#[cfg(feature = "std")]
+				#[cfg(all(feature = "std", not(fuzzing)))]
 				{
 					use std::time::{SystemTime, UNIX_EPOCH};
 					let now = SystemTime::now().duration_since(UNIX_EPOCH);
@@ -512,7 +512,8 @@ impl OMNameResolver {
 					// (we assume no more than two hours, though the actual limits are rather
 					// complicated).
 					// Thus, we have to let the proof times be rather fuzzy.
-					let max_time_offset = if cfg!(feature = "std") { 0 } else { 60 * 2 };
+					let max_time_offset =
+						if cfg!(all(feature = "std", not(fuzzing))) { 0 } else { 60 * 2 };
 					if validated_rrs.valid_from > time + max_time_offset {
 						return None;
 					}

lightning/src/routing/gossip.rs

@@ -843,7 +843,7 @@ impl<G: Deref<Target = NetworkGraph<L>>, U: UtxoLookup, L: Logger> BaseMessageHa
 		let mut gossip_start_time = 0;
 		#[allow(unused)]
 		let should_sync = self.should_request_full_sync();
-		#[cfg(feature = "std")]
+		#[cfg(all(feature = "std", not(fuzzing)))]
 		{
 			gossip_start_time = SystemTime::now()
 				.duration_since(UNIX_EPOCH)
@@ -2195,7 +2195,7 @@ impl<L: Logger> NetworkGraph<L> {
 
 		#[allow(unused_mut, unused_assignments)]
 		let mut announcement_received_time = 0;
-		#[cfg(feature = "std")]
+		#[cfg(all(feature = "std", not(fuzzing)))]
 		{
 			announcement_received_time = SystemTime::now()
 				.duration_since(UNIX_EPOCH)
@@ -2235,11 +2235,11 @@ impl<L: Logger> NetworkGraph<L> {
 	///
 	/// The channel and any node for which this was their last channel are removed from the graph.
 	pub fn channel_failed_permanent(&self, short_channel_id: u64) {
-		#[cfg(feature = "std")]
+		#[cfg(all(feature = "std", not(fuzzing)))]
 		let current_time_unix = Some(
 			SystemTime::now().duration_since(UNIX_EPOCH).expect("Time must be > 1970").as_secs(),
 		);
-		#[cfg(not(feature = "std"))]
+		#[cfg(any(not(feature = "std"), fuzzing))]
 		let current_time_unix = None;
 
 		self.channel_failed_permanent_with_time(short_channel_id, current_time_unix)
@@ -2262,11 +2262,11 @@ impl<L: Logger> NetworkGraph<L> {
 	/// Marks a node in the graph as permanently failed, effectively removing it and its channels
 	/// from local storage.
 	pub fn node_failed_permanent(&self, node_id: &PublicKey) {
-		#[cfg(feature = "std")]
+		#[cfg(all(feature = "std", not(fuzzing)))]
 		let current_time_unix = Some(
 			SystemTime::now().duration_since(UNIX_EPOCH).expect("Time must be > 1970").as_secs(),
 		);
-		#[cfg(not(feature = "std"))]
+		#[cfg(any(not(feature = "std"), fuzzing))]
 		let current_time_unix = None;
 
 		let node_id = NodeId::from_pubkey(node_id);
@@ -2303,7 +2303,6 @@ impl<L: Logger> NetworkGraph<L> {
 		}
 	}
 
-	#[cfg(feature = "std")]
 	/// Removes information about channels that we haven't heard any updates about in some time.
 	/// This can be used regularly to prune the network graph of channels that likely no longer
 	/// exist.
@@ -2318,8 +2317,9 @@ impl<L: Logger> NetworkGraph<L> {
 	/// This method will also cause us to stop tracking removed nodes and channels if they have been
 	/// in the map for a while so that these can be resynced from gossip in the future.
 	///
-	/// This method is only available with the `std` feature. See
+	/// This method is only available with the `std` feature (and not during fuzzing). See
 	/// [`NetworkGraph::remove_stale_channels_and_tracking_with_time`] for non-`std` use.
+	#[cfg(all(feature = "std", not(fuzzing)))]
 	pub fn remove_stale_channels_and_tracking(&self) {
 		let time =
 			SystemTime::now().duration_since(UNIX_EPOCH).expect("Time must be > 1970").as_secs();
@@ -2476,7 +2476,7 @@ impl<L: Logger> NetworkGraph<L> {
 			});
 		}
 
-		#[cfg(all(feature = "std", not(test), not(feature = "_test_utils")))]
+		#[cfg(all(feature = "std", not(test), not(feature = "_test_utils"), not(fuzzing)))]
 		{
 			// Note that many tests rely on being able to set arbitrarily old timestamps, thus we
 			// disable this check during tests!

lightning/src/util/hash_tables.rs

@@ -6,11 +6,11 @@
 pub use hashbrown::hash_map;
 
 mod hashbrown_tables {
-	#[cfg(all(feature = "std", not(test)))]
+	#[cfg(all(feature = "std", not(test), not(fuzzing)))]
 	mod hasher {
 		pub use std::collections::hash_map::RandomState;
 	}
-	#[cfg(all(feature = "std", test))]
+	#[cfg(all(feature = "std", any(test, fuzzing)))]
 	mod hasher {
 		#![allow(deprecated)] // hash::SipHasher was deprecated in favor of something only in std.
 		use core::hash::{BuildHasher, Hasher};
@@ -27,7 +27,10 @@ mod hashbrown_tables {
 
 		impl RandomState {
 			pub fn new() -> RandomState {
-				if std::env::var("LDK_TEST_DETERMINISTIC_HASHES").map(|v| v == "1").unwrap_or(false)
+				if cfg!(fuzzing)
+					|| std::env::var("LDK_TEST_DETERMINISTIC_HASHES")
+						.map(|v| v == "1")
+						.unwrap_or(false)
 				{
 					RandomState::Deterministic
 				} else {