Trick event handlers into returning that they exist during fuzzing

src/EventRegistry.cc

@@ -136,4 +136,14 @@ void EventRegistry::SetErrorHandler(std::string_view name)
 	                          std::string(name).c_str());
 	}
 
+void EventRegistry::ActivateAllHandlers()
+	{
+	auto event_names = AllHandlers();
+	for ( const auto& name : event_names )
+		{
+		if ( auto event = Lookup(name) )
+			event->SetGenerateAlways();
+		}
+	}
+
 	} // namespace zeek

src/EventRegistry.h

@@ -60,6 +60,17 @@ public:
 
 	void PrintDebug();
 
+	/**
+	 * Marks all event handlers as active.
+	 *
+	 * By default, zeek does not generate (raise) events that have not handled by
+	 * any scripts. This means that these events will be invisible to a lot of other
+	 * event handlers - and will not raise :zeek:id:`new_event`. Calling this
+	 * function will cause all event handlers to be raised. This is likely only
+	 * useful for debugging and fuzzing, and likely causes reduced performance.
+	 */
+	void ActivateAllHandlers();
+
 private:
 	std::map<std::string, std::unique_ptr<EventHandler>, std::less<>> handlers;
 	// Tracks whether a given event handler was registered in a

src/fuzzers/fuzzer-setup.h

@@ -4,6 +4,7 @@
 #include <cstdlib>
 
 #include "zeek/Event.h"
+#include "zeek/EventRegistry.h"
 #include "zeek/broker/Manager.h"
 #include "zeek/file_analysis/Manager.h"
 #include "zeek/session/Manager.h"
@@ -41,6 +42,11 @@ extern "C" int LLVMFuzzerInitialize(int* argc, char*** argv)
 	if ( zeek::detail::setup(*argc, *argv, &options).code )
 		abort();
 
+	// We have to trick the event handlers into returning true that they exist here
+	// even if they don't, because otherwise we lose a bit of coverage where if
+	// statements return false that would otherwise not.
+	zeek::event_registry->ActivateAllHandlers();
+
 	return 0;
 	}
 

src/zeek.bif

@@ -5366,16 +5366,7 @@ function match_signatures%(c: connection, pattern_type: int, s: string,
 ## only useful for debugging and causes reduced performance.
 function generate_all_events%(%) : bool
 	%{
-	auto event_names = event_registry->AllHandlers();
-	for ( const auto& name: event_names )
-		{
-		auto event = event_registry->Lookup(name);
-		if ( event == nullptr )
-			continue;
-
-		event->SetGenerateAlways();
-		}
-
+	event_registry->ActivateAllHandlers();
 	return zeek::val_mgr->True();
 	%}