Restructuring the plugin API to accomodate hooks.

I got rid of the earlier separate InterpreterPlugin class. Instead
Plugin now has a set of virtual methods HookSomething()... that
plugins can override. For efficiency purposes, they however need to
register first that they are interested in a hook, otherwise the
virtual method will never be called. The idea is to extend the set of
hooks over time as we figure out what's useful.

This is a checkpoint commit that's essentially untested and probably
broken. It compiles, though.

src/Event.cc

@@ -78,8 +78,7 @@ EventMgr::~EventMgr()
 
 void EventMgr::QueueEvent(Event* event)
 	{
-	if ( plugin_mgr->QueueEvent(event) )
+	PLUGIN_HOOK_VOID(HOOK_QUEUE_EVENT, HookQueueEvent(event));
-    	return;
 
 	if ( ! head )
 		head = tail = event;
@@ -119,7 +118,7 @@ void EventMgr::Drain()
 
 	SegmentProfiler(segment_logger, "draining-events");
 
-	plugin_mgr->DrainEvents();
+	PLUGIN_HOOK_VOID(HOOK_DRAIN_EVENTS, HookDrainEvents());
 
 	draining = true;
 	while ( head )

src/Func.cc

@@ -283,7 +283,7 @@ Val* BroFunc::Call(val_list* args, Frame* parent) const
 	DEBUG_MSG("Function: %s\n", id->Name());
 #endif
 
-	Val* plugin_result = plugin_mgr->CallFunction(this, args);
+	Val* plugin_result = PLUGIN_HOOK_WITH_RESULT(HOOK_CALL_FUNCTION, HookCallFunction(this, args), 0);
 
 	if ( plugin_result )
 		{

src/Net.cc

@@ -148,7 +148,7 @@ RETSIGTYPE watchdog(int /* signo */)
 void net_update_time(double new_network_time)
 	{
 	network_time = new_network_time;
-	plugin_mgr->UpdateNetworkTime(network_time);
+	PLUGIN_HOOK_VOID(HOOK_UPDATE_NETWORK_TIME, HookUpdateNetworkTime(new_network_time));
 	}
 
 void net_init(name_list& interfaces, name_list& readfiles,

src/main.cc

@@ -224,7 +224,6 @@ void usage()
 	fprintf(stderr, "    $BROPATH                       | file search path (%s)\n", bro_path().c_str());
 	fprintf(stderr, "    $BROMAGIC                      | libmagic mime magic database search path (%s)\n", bro_magic_path());
 	fprintf(stderr, "    $BRO_PLUGINS                   | plugin search path (%s)\n", bro_plugin_path());
-	fprintf(stderr, "    $BRO_PREFIXES                  | prefix list (%s)\n", bro_prefixes());
 	fprintf(stderr, "    $BRO_PREFIXES                  | prefix list (%s)\n", bro_prefixes().c_str());
 	fprintf(stderr, "    $BRO_DNS_FAKE                  | disable DNS lookups (%s)\n", bro_dns_fake());
 	fprintf(stderr, "    $BRO_SEED_FILE                 | file to load seeds from (not set)\n");

src/plugin/Macros.h

@@ -64,6 +64,14 @@
  */
 #define BRO_PLUGIN_VERSION(v) SetVersion(v)
 
+/**
+ * Enables a hook for the plugin. Once enabled, Bro will call the
+ * corresponding virtual function.
+ *
+ * @param h The \a HookType to able.
+ */
+#define BRO_PLUGIN_ENABLE_HOOK(h) EnableHook(h)
+
 /**
  * Adds script-level items defined in a \c *.bif file to what the plugin
  * provides.

src/plugin/Manager.cc

@@ -21,11 +21,20 @@ string Manager::current_sopath;
 Manager::Manager()
 	{
 	init = false;
+	hooks = new hook_list*[NUM_HOOKS];
+
+	for ( int i = 0; i < NUM_HOOKS; i++ )
+		hooks[i] = 0;
 	}
 
 Manager::~Manager()
 	{
 	assert(! init);
+
+	for ( int i = 0; i < NUM_HOOKS; i++ )
+		delete hooks[i];
+
+	delete [] hooks;
 	}
 
 void Manager::LoadPluginsFrom(const string& dir)
@@ -204,15 +213,6 @@ bool Manager::RegisterPlugin(Plugin *plugin)
 	return true;
 	}
 
-static bool interpreter_plugin_cmp(const InterpreterPlugin* a, const InterpreterPlugin* b)
-	{
-	if ( a->Priority() == b->Priority() )
-		return a->Name() < b->Name();
-
-	// Reverse sort.
-	return a->Priority() > b->Priority();
-	}
-
 void Manager::InitPreScript()
 	{
 	assert(! init);
@@ -221,26 +221,9 @@ void Manager::InitPreScript()
 		{
 		Plugin* plugin = *i;
 
-		if ( plugin->PluginType() == Plugin::INTERPRETER )
-			interpreter_plugins.push_back(dynamic_cast<InterpreterPlugin *>(plugin));
-
 		plugin->InitPreScript();
-
-		// Track the file extensions the plugin can handle.
-		std::stringstream ext(plugin->FileExtensions());
-
-		// Split at ":".
-		std::string e;
-
-		while ( std::getline(ext, e, ':') )
-			{
-			DBG_LOG(DBG_PLUGINS, "Plugin %s handles *.%s", plugin->Name(), e.c_str());
-			extensions.insert(std::make_pair(e, plugin));
-			}
 		}
 
-	interpreter_plugins.sort(interpreter_plugin_cmp);
-
 	init = true;
 	}
 
@@ -273,28 +256,6 @@ void Manager::FinishPlugins()
 	init = false;
 	}
 
-int Manager::TryLoadFile(const char* file)
-	{
-	assert(file);
-	const char* ext = strrchr(file, '.');
-
-	if ( ! ext )
-		return -1;
-
-	extension_map::iterator i = extensions.find(++ext);
-	if ( i == extensions.end() )
-		return -1;
-
-	Plugin* plugin = i->second;
-
-	DBG_LOG(DBG_PLUGINS, "Loading %s with %s", file, plugin->Name());
-
-	if ( i->second->LoadFile(file) )
-		return 1;
-
-	return 0;
-	}
-
 Manager::plugin_list Manager::Plugins() const
 	{
 	return *Manager::PluginsInternal();
@@ -310,66 +271,135 @@ Manager::plugin_list* Manager::PluginsInternal()
 	return plugins;
 	}
 
-Val* Manager::CallFunction(const Func* func, val_list* args) const
+static bool hook_cmp(std::pair<int, Plugin*> a, std::pair<int, Plugin*> b)
 	{
-	Val* result = 0;
+	if ( a.first == b.first )
+		return a.second->Name() < a.second->Name();
 
-	for ( interpreter_plugin_list::const_iterator i = interpreter_plugins.begin();
+	// Reverse sort.
-	      i != interpreter_plugins.end() && ! result; i++ )
+	return a.first > b.first;
+	}
+
+std::list<std::pair<HookType, int> > Manager::HooksEnabledForPlugin(const Plugin* plugin) const
+	{
+	std::list<std::pair<HookType, int> > enabled;
+
+	for ( int i = 0; i < NUM_HOOKS; i++ )
 		{
-		result = (*i)->CallFunction(func, args);
+		hook_list* l = hooks[i];
 
-		if ( result )
+		if ( ! l )
+			continue;
+
+		for ( hook_list::iterator j = l->begin(); j != l->end(); j++ )
 			{
-			DBG_LOG(DBG_PLUGINS, "Plugin %s replaced call to %s", (*i)->Name(), func->Name());
+			if ( (*j).second == plugin )
-			return result;
+				enabled.push_back(std::make_pair((HookType)i, (*j).first));
 			}
 		}
 
+	return enabled;
+	}
+
+void Manager::EnableHook(HookType hook, Plugin* plugin, int prio)
+	{
+	if ( ! hooks[hook] )
+		hooks[hook] = new hook_list;
+
+	hooks[hook]->push_back(std::make_pair(prio, plugin));
+	hooks[hook]->sort(hook_cmp);
+	}
+
+void Manager::DisableHook(HookType hook, Plugin* plugin)
+	{
+	hook_list* l = hooks[hook];
+
+	if ( ! l )
+		return;
+
+	for ( hook_list::iterator i = l->begin(); i != l->end(); i++ )
+		{
+		if ( (*i).second == plugin )
+			{
+			l->erase(i);
+			break;
+			}
+		}
+
+	if ( l->empty() )
+		{
+		delete l;
+		hooks[hook] = 0;
+		}
+	}
+
+int Manager::HookLoadFile(const char* file)
+	{
+	hook_list* l = hooks[HOOK_LOAD_FILE];
+
+	for ( hook_list::iterator i = l->begin(); l && i != l->end(); i++ )
+		{
+		Plugin* p = (*i).second;
+
+		int rc = p->HookLoadFile(file);
+
+		if ( rc >= 0 )
+			return rc;
+		}
+
+	return -1;
+	}
+
+Val* Manager::HookCallFunction(const Func* func, val_list* args) const
+	{
+	hook_list* l = hooks[HOOK_CALL_FUNCTION];
+
+	for ( hook_list::iterator i = l->begin(); l && i != l->end(); i++ )
+		{
+		Plugin* p = (*i).second;
+
+		Val* v = p->HookCallFunction(func, args);
+
+		if ( v )
+			return v;
+		}
+
 	return 0;
 	}
 
-bool Manager::QueueEvent(Event* event) const
+bool Manager::HookQueueEvent(Event* event) const
 	{
-	for ( interpreter_plugin_list::const_iterator i = interpreter_plugins.begin();
+	hook_list* l = hooks[HOOK_QUEUE_EVENT];
-	      i != interpreter_plugins.end(); i++ )
+
+	for ( hook_list::iterator i = l->begin(); l && i != l->end(); i++ )
 		{
-		if ( (*i)->QueueEvent(event) )
+		Plugin* p = (*i).second;
-			{
+
-			DBG_LOG(DBG_PLUGINS, "Plugin %s handled queueing of event %s", (*i)->Name(), event->Handler()->Name());
+		if ( p->HookQueueEvent(event) )
 			return true;
-			}
 		}
 
 	return false;
 	}
 
-
+void Manager::HookDrainEvents() const
-void Manager::UpdateNetworkTime(double network_time) const
 	{
-	for ( interpreter_plugin_list::const_iterator i = interpreter_plugins.begin();
+	hook_list* l = hooks[HOOK_DRAIN_EVENTS];
-	      i != interpreter_plugins.end(); i++ )
-		(*i)->UpdateNetworkTime(network_time);
-	}
 
-void Manager::DrainEvents() const
+	for ( hook_list::iterator i = l->begin(); l && i != l->end(); i++ )
-	{
-	for ( interpreter_plugin_list::const_iterator i = interpreter_plugins.begin();
-	      i != interpreter_plugins.end(); i++ )
-		(*i)->DrainEvents();
-	}
-
-void Manager::DisableInterpreterPlugin(const InterpreterPlugin* plugin)
-	{
-	for ( interpreter_plugin_list::iterator i = interpreter_plugins.begin();
-	      i != interpreter_plugins.end(); i++ )
 		{
-		if ( *i == plugin )
+		Plugin* p = (*i).second;
-			{
+		p->HookDrainEvents();
-			interpreter_plugins.erase(i);
-			return;
-			}
 		}
 	}
 
+void Manager::HookUpdateNetworkTime(double network_time) const
+	{
+	hook_list* l = hooks[HOOK_UPDATE_NETWORK_TIME];
 
+	for ( hook_list::iterator i = l->begin(); l && i != l->end(); i++ )
+		{
+		Plugin* p = (*i).second;
+		p->HookUpdateNetworkTime(network_time);
+		}
+	}

src/plugin/Manager.h

@@ -12,6 +12,14 @@
 
 namespace plugin {
 
+// Macros that trigger a plugin hook. We put this into macros to short-cut
+// the code for the most common case that no plugin defines the hook.
+#define PLUGIN_HOOK_WITH_RESULT(hook, method_call, default_result) \
+	(plugin_mgr->HavePluginForHook(plugin::hook) ? plugin_mgr->method_call : (default_result))
+
+#define PLUGIN_HOOK_VOID(hook, method_call) \
+	if ( plugin_mgr->HavePluginForHook(plugin::hook) ) plugin_mgr->method_call;
+
 /**
  * A singleton object managing all plugins.
  */
@@ -19,7 +27,6 @@ class Manager
 {
 public:
 	typedef std::list<Plugin*> plugin_list;
-	typedef std::list<InterpreterPlugin*> interpreter_plugin_list;
 	typedef Plugin::component_list component_list;
 
 	/**
@@ -30,7 +37,7 @@ public:
 	/**
 	 * Destructor.
 	 */
-	~Manager();
+	virtual ~Manager();
 
 	/**
 	 * Loads all plugins dynamically from a set of directories. Multiple
@@ -71,22 +78,6 @@ public:
 	 */
 	void FinishPlugins();
 
-	/**
-	 * This tries to load the given file by searching for a plugin that
-	 * support that extension. If a correspondign plugin is found, it's
-	 * asked to loead the file. If that fails, the method reports an 
-	 * error message.
-	 *
-	 * This method must be called only between InitPreScript() and
-	 * InitPostScript().
-	 *
-	 * @return 1 if the file was sucessfully loaded by a plugin; 0 if a
-	 * plugin was found that supports the file's extension, yet it
-	 * encountered a problem loading the file; and -1 if we don't have a
-	 * plugin that supports this extension.
-	 */
-	int TryLoadFile(const char* file);
-
 	/**
 	 * Returns a list of all available plugins. This includes all that
 	 * are compiled in statically, as well as those loaded dynamically so
@@ -102,7 +93,65 @@ public:
 	template<class T> std::list<T *> Components() const;
 
 	/**
-	 * Filters a function/event/hook call through all interpreter plugins.
+	 * Returns true if there's at least one plugin interested in a given
+	 * hook.
+	 *
+	 * @param The hook to check.
+	 *
+	 * @return True if there's a plugin for that hook.
+	 */
+	bool HavePluginForHook(HookType hook) const
+		{
+		// Inline to make avoid the function call.
+		return hooks[hook] != 0;
+		}
+
+	/**
+	 * Returns all the hooks, with their priorities, that are currently
+	 * enabled for a given plugin.
+	 *
+	 * @param plugin The plugin to return the hooks for.
+	 */
+	std::list<std::pair<HookType, int> > HooksEnabledForPlugin(const Plugin* plugin) const;
+
+	/**
+	 * Enables a hook for a given plugin.
+	 *
+	 * hook: The hook to enable.
+	 *
+	 * plugin: The plugin defining the hook.
+	 *
+	 * prio: The priority to associate with the plugin for this hook.
+	 */
+	void EnableHook(HookType hook, Plugin* plugin, int prio);
+
+	/**
+	 * Disables a hook for a given plugin.
+	 *
+	 * hook: The hook to enable.
+	 *
+	 * plugin: The plugin that used to define the hook.
+	 */
+	void DisableHook(HookType hook, Plugin* plugin);
+
+	// Hook entry functions.
+
+	/**
+	 * Hook that gives plugins a chance to take over loading an input
+	 * input file. This method must be called between InitPreScript() and
+	 * InitPostScript() for each input file Bro is about to load, either
+	 * given on the command line or via @load script directives. The hook
+	 * can take over the file, in which case Bro must not further process
+	 * it otherwise.
+	 *
+	 * @return 1 if a plugin took over the file and loaded it
+	 * successfully; 0 if a plugin took over the file but had trouble
+	 * loading it; and -1 if no plugin was interested in the file at all.
+	 */
+	virtual int HookLoadFile(const char* file);
+
+	/**
+	 * Hook that filters calls to a script function/event/hook.
 	 *
 	 * @param func The function to be called.
 	 *
@@ -113,39 +162,29 @@ public:
 	 * events, it may be any Val and must be ignored). If no plugin
 	 * handled the call, the method returns null.
 	 */
-	Val* CallFunction(const Func* func, val_list* args) const;
+	Val* HookCallFunction(const Func* func, val_list* args) const;
-
-    /**
-     * Filter the queuing of an event through all interpreter plugins.
-     *
-     * @param event The event to be queued; it may be modified.
-     *
-     * @return Returns true if a plugin handled the queuing; in that case the
-     * plugin will have taken ownership.
-	 *
-     */
-	bool QueueEvent(Event* event) const;
 
 	/**
-	 * Informs all interpreter plugins about an update in network time.
+	 * Hook that filters the queuing of an event.
 	 *
-	 * @param networkt_time The new network time.
+	 * @param event The event to be queued; it may be modified.
+	 *
+	 * @return Returns true if a plugin handled the queuing; in that case
+	 * the plugin will have taken ownership.
 	 */
-	void UpdateNetworkTime(double network_time) const;
+	bool HookQueueEvent(Event* event) const;
 
 	/**
-	 * Informs all interpreter plugins that the event queue has been drained.
+	 * Hook that informs plugins about an update in network time.
+	 *
+	 * @param network_time The new network time.
 	 */
-	void DrainEvents() const;
+	void HookUpdateNetworkTime(double network_time) const;
 
-    /**
+	/**
-     * Disables an interpreter plugin's hooking of the script interpreter.
+	 * Hooks that informs plugins that the event queue is being drained.
-     * The remaining functionality of the Plugin base class remains
+	 */
-     * available.
+	void HookDrainEvents() const;
-     *
-     * @param plugin The plugin to disable.
-     */
-    void DisableInterpreterPlugin(const InterpreterPlugin* plugin);
 
 	/**
 	 * Internal method that registers a freshly instantiated plugin with
@@ -177,13 +216,17 @@ protected:
 	int LoadPlugin(const std::string& dir);
 
 private:
+	// A hook list keeps pairs of plugin and priority interested in a
+	// given hook.
+	typedef std::list<std::pair<int, Plugin*> > hook_list;
+
 	static plugin_list* PluginsInternal();
 
 	bool init;
-	typedef std::map<std::string, Plugin*> extension_map;
-	extension_map extensions;
 
-	interpreter_plugin_list interpreter_plugins;
+	// An array indexed by HookType. An entry is null if there's no hook
+	// of that type enabled.
+	hook_list** hooks;
 
 	static string current_dir;
 	static string current_sopath;

src/plugin/Plugin.cc

@@ -10,6 +10,22 @@
 
 using namespace plugin;
 
+const char* hook_name(HookType h)
+	{
+	static const char* hook_names[int(NUM_HOOKS) + 1] = {
+		// Order must match that of HookType.
+		"LoadFile",
+		"CallFunction",
+		"QueueEvent",
+		"DrainEvents",
+		"UpdateNetworkTime",
+		// End marker.
+		"<end>",
+	};
+
+	return hook_names[int(h)];
+	}
+
 BifItem::BifItem(const char* arg_id, Type arg_type)
 	{
 	id = copy_string(arg_id);
@@ -49,7 +65,6 @@ Plugin::Plugin()
 	dynamic = false;
 	base_dir = 0;
 	sopath = 0;
-	extensions = 0;
 
 	Manager::RegisterPlugin(this);
 	}
@@ -62,12 +77,6 @@ Plugin::~Plugin()
 	delete [] description;
 	delete [] base_dir;
 	delete [] sopath;
-	delete [] extensions;
-	}
-
-Plugin::Type Plugin::PluginType() const
-	{
-	return STANDARD;
 	}
 
 const char* Plugin::Name() const
@@ -170,22 +179,6 @@ Plugin::bif_item_list Plugin::CustomBifItems() const
 	return bif_item_list();
 	}
 
-const char* Plugin::FileExtensions() const
-	{
-	return extensions ? extensions : "";
-	}
-
-void Plugin::SetFileExtensions(const char* ext)
-	{
-	extensions = copy_string(ext);
-	}
-
-bool Plugin::LoadFile(const char* file)
-	{
-	reporter->InternalError("Plugin::LoadFile not overriden for %s", file);
-	return false;
-	}
-
 void Plugin::Done()
 	{
 	for ( component_list::const_iterator i = components.begin(); i != components.end(); i++ )
@@ -204,18 +197,9 @@ static bool component_cmp(const Component* a, const Component* b)
 	return a->Name() < b->Name();
 	}
 
-void Plugin::AddComponent(Component* c)
-	{
-	components.push_back(c);
-
-	// Sort components by name to make sure we have a deterministic
-	// order.
-	components.sort(component_cmp);
-	}
-
 bool Plugin::LoadBroFile(const char* file)
 	{
-	add_input_file(file);
+	::add_input_file(file);
 	return true;
 	}
 
@@ -230,6 +214,53 @@ void Plugin::AddBifItem(const char* name, BifItem::Type type)
 	bif_items.push_back(bi);
 	}
 
+void Plugin::AddComponent(Component* c)
+	{
+	components.push_back(c);
+
+	// Sort components by name to make sure we have a deterministic
+	// order.
+	components.sort(component_cmp);
+	}
+
+Plugin::hook_list Plugin::EnabledHooks() const
+	{
+	return plugin_mgr->HooksEnabledForPlugin(this);
+	}
+
+void Plugin::EnableHook(HookType hook, int priority)
+	{
+	plugin_mgr->EnableHook(hook, this, priority);
+	}
+
+void Plugin::DisableHook(HookType hook)
+	{
+	plugin_mgr->DisableHook(hook, this);
+	}
+
+int Plugin::HookLoadFile(const char* file)
+	{
+	return -1;
+	}
+
+Val* Plugin::HookCallFunction(const Func* func, val_list* args)
+	{
+	return 0;
+	}
+
+bool Plugin::HookQueueEvent(Event* event)
+	{
+	return false;
+	}
+
+void Plugin::HookDrainEvents()
+	{
+	}
+
+void Plugin::HookUpdateNetworkTime(double network_time)
+	{
+	}
+
 void Plugin::Describe(ODesc* d) const
 	{
 	d->Add("Plugin: ");
@@ -256,18 +287,6 @@ void Plugin::Describe(ODesc* d) const
 	else
 		d->Add(" (built-in)");
 
-	switch ( PluginType() ) {
-	case STANDARD:
-		break;
-
-	case INTERPRETER:
-		d->Add( " (interpreter plugin)");
-		break;
-
-	default:
-		reporter->InternalError("unknown plugin type in Plugin::Describe");
-	}
-
 	d->Add("\n");
 
 	if ( d->IsShort() )
@@ -317,48 +336,19 @@ void Plugin::Describe(ODesc* d) const
 		d->Add((*i).GetID());
 		d->Add("\n");
 		}
+
+	hook_list hooks = EnabledHooks();
+
+	for ( hook_list::iterator i = hooks.begin(); i != hooks.end(); i++ )
+		{
+		HookType hook = (*i).first;
+		int prio = (*i).second;
+
+		d->Add("    Implements ");
+		d->Add(hook_name(hook));
+		d->Add(" (priority ");
+		d->Add(prio);
+		d->Add("]\n");
+		}
 	}
 
-InterpreterPlugin::InterpreterPlugin(int arg_priority)
-	{
-	priority = arg_priority;
-	}
-
-InterpreterPlugin::~InterpreterPlugin()
-	{
-	}
-
-int InterpreterPlugin::Priority() const
-	{
-	return priority;
-	}
-
-Plugin::Type InterpreterPlugin::PluginType() const
-	{
-	return INTERPRETER;
-	}
-
-Val* InterpreterPlugin::CallFunction(const Func* func, val_list* args)
-	{
-	return 0;
-	}
-
-bool InterpreterPlugin::QueueEvent(Event* event)
-	{
-	return false;
-	}
-
-void InterpreterPlugin::UpdateNetworkTime(double network_time)
-	{
-	}
-
-void InterpreterPlugin::DrainEvents()
-	{
-	}
-
-void InterpreterPlugin::DisableInterpreterPlugin() const
-	{
-	plugin_mgr->DisableInterpreterPlugin(this);
-	}
-
-

src/plugin/Plugin.h

@@ -17,6 +17,21 @@ namespace plugin  {
 class Manager;
 class Component;
 
+/**
+ * Hook types that a plugin may define. Each label maps to the corresponding
+ * virtual method in \a Plugin.
+ */
+enum HookType {
+	// Note: when changing this table, update hook_name() in Plugin.cc.
+	HOOK_LOAD_FILE,
+	HOOK_CALL_FUNCTION,
+	HOOK_QUEUE_EVENT,
+	HOOK_DRAIN_EVENTS,
+	HOOK_UPDATE_NETWORK_TIME,
+	// End marker.
+	NUM_HOOKS,
+};
+
 /**
  * A class describing an item defined in \c *.bif file.
  */
@@ -70,45 +85,37 @@ private:
 /**
  * Base class for all plugins.
  *
- * Plugins encapsulate functionality that extends one of Bro's major
+ * Plugins encapsulate functionality that extends one or more of Bro's major
  * subsystems, such as analysis of a specific protocol, or logging output in
- * a particular format. A plugin is a logical container that can provide one
+ * a particular format. A plugin acts a logical container that can provide a
- * or more \a components implementing functionality. For example, a RPC
+ * set of different functionality. Specifically, it may:
- * plugin could provide analyzer for set of related protocols (RPC, NFS,
+ *
- * etc.), each of which would be a separate component. Likewise, a SQLite
+ * - Provide one or more \a components implementing functionality. For
- * plugin could provide both a writer and reader component. In addition to
+ *   example, a RPC plugin could provide analyzer for set of related
- * components, a plugin can also provide of script-level elements defined in
+ *   protocols (RPC, NFS, etc.), each of which would be a separate component.
- * *.bif files.
+ *   Likewise, a SQLite plugin could provide both a writer and reader
+ *   component. In addition to components, a plugin can also provide of
+ *   script-level elements defined in *.bif files.
+ *
+ * - Provide BiF elements (functions, events, types, globals).
+ *
+ * - Provide hooks (aka callbacks) into Bro's core processing to inject
+ *   and/or alter functionality.
+ *
+ * Note that a plugin needs to explicitly register all the functionality it
+ * provides. For components, it needs to call AddComponent(); for BiFs
+ * AddBifItem(); and for hooks EnableHook() and then also implemennt the
+ * corresponding virtual method).
  *
- * Currently, all plugins are compiled statically into the final Bro binary.
- * Later, we will extend the infrastructure to also support plugins loaded
- * dynamically as shared libraries.
  */
 class Plugin {
 public:
 	typedef std::list<Component *> component_list;
 	typedef std::list<BifItem> bif_item_list;
+	typedef std::list<std::pair<HookType, int> > hook_list;
 	typedef std::list<std::pair<const char*, int> > bif_init_func_result;
 	typedef void (*bif_init_func)(Plugin *);
 
-	/**
-	 * Type of a plugin. Plugin types are set implicitly by deriving from
-	 * the corresponding base class. */
-	enum Type {
-		/**
-		 * A standard plugin. This is the type for all plugins
-		 * derived directly from \a Plugin. */
-		STANDARD,
-
-		/**
-		 * An interpreter plugin. These plugins get hooked into the
-		 * script interpreter and can modify, or even replace, its
-		 * execution of Bro script code. To create an interpreter
-		 * plugin, derive from \aInterpreterPlugin.
-		 */
-		INTERPRETER
-	};
-
 	/**
 	 * Constructor.
 	 */
@@ -119,11 +126,6 @@ public:
 	 */
 	virtual ~Plugin();
 
-	/**
-	 * Returns the type of the plugin.
-	 */
-	virtual Type PluginType() const;
-
 	/**
 	 * Returns the name of the plugin.
 	 */
@@ -146,11 +148,6 @@ public:
 	 */
 	bool DynamicPlugin() const;
 
-	/**
-	 * Returns a colon-separated list of file extensions the plugin handles.
-	 */
-	const char* FileExtensions() const;
-
 	/**
 	 * For dynamic plugins, returns the base directory from which it was
 	 * loaded. For static plugins, returns null.
@@ -201,8 +198,8 @@ public:
 
 	/**
 	 * Finalizer method that derived classes can override for performing
-	 * custom tasks at shutdown. Implementation must call the parent's
+	 * custom tasks at shutdown.  This can be overridden by derived
-	 * version.
+	 * classes; they must however call the parent's implementation.
 	 */
 	virtual void Done();
 
@@ -216,12 +213,14 @@ public:
 	void Describe(ODesc* d) const;
 
 	/**
-	 * Registering an individual BiF that the plugin defines.  The
+	 * Registers an individual BiF that the plugin defines.  The
 	 * information is for informational purpuses only and will show up in
 	 * the result of BifItems() as well as in the Describe() output.
 	 * Another way to add this information is via overriding
 	 * CustomBifItems().
 	 *
+	 * \todo Do we need both this an CustomBifItems()?
+	 *
 	 * @param name The name of the BiF item.
 	 *
 	 * @param type The item's type.
@@ -229,10 +228,10 @@ public:
 	void AddBifItem(const char* name, BifItem::Type type);
 
 	/**
-	 * Adds a file to the list of files Bro loads at startup. This will
+	 * Adds a file to the list of files that Bro loads at startup. This
-	 * normally be a Bro script, but it passes through the plugin system
+	 * will normally be a Bro script, but it passes through the plugin
-	 * as well to load files with other extensions as supported by any of
+	 * system as well to load files with other extensions as supported by
-	 * the current plugins. In other words, calling this method is
+	 * any of the current plugins. In other words, calling this method is
 	 * similar to given a file on the command line. Note that the file
 	 * may be only queued for now, and actually loaded later.
 	 *
@@ -245,161 +244,99 @@ public:
 	 */
 	bool LoadBroFile(const char* file);
 
-protected:
-	friend class Manager;
-
-	/**
-	 * Sets the plugins name.
-	 *
-	 * @param name The name. Makes a copy internally.
-	 */
-	void SetName(const char* name);
-
-	/**
-	 * Sets the plugin's textual description.
-	 *
-	 * @param name The description. Makes a copy internally.
-	 */
-	void SetDescription(const char* descr);
-
-	/**
-	 * Sets the plugin's version.
-	 *
-	 * @param version The version.
-	 */
-	void SetVersion(int version);
-
-	/**
-	 * Sets the API version the plugin requires.
-	 * BRO_PLUGIN_VERSION_BUILTIN indicates that it's a plugin linked in
-	 * statically.
-	 */
-	void SetAPIVersion(int version);
-
-	/**
-	 * Marks the plugin as statically or dynamically linked.
-	 *
-	 * @param dynamic True if this is a dynamically linked plugin.
-	 */
-	void SetDynamicPlugin(bool dynamic);
-
-	/**
-	 * Reports the extensions of input files the plugin handles. If Bro
-	 * wants to load a file with one of these extensions it will pass
-	 * them to LoadFile() and then then ignore otherwise.
-	 *
-	 * ext: A list of colon-separated file extensions the plugin handles.
-	 */
-	void SetFileExtensions(const char* ext);
-
-	/**
-	 * Sets the base directory and shared library path from which the
-	 * plugin was loaded. This should be called only from the manager for
-	 * dynamic plugins.
-	 *
-	 * @param dir The plugin directory. The functions makes an internal
-	 * copy of string.
-	 *
-	 * @param sopath The full path the shared library loaded. The
-	 * functions makes an internal copy of string.
-	 */
-	void SetPluginLocation(const char* dir, const char* sopath);
-
-	/**
-	 * Takes ownership.
-	 */
-	void AddComponent(Component* c);
-
-	/**
-	 * Virtual method that can be overriden by derived class to provide
-	 * information about further script-level elements that the plugins
-	 * provides on its own, i.e., outside of the standard mechanism
-	 * processing *.bif files automatically. The returned information is
-	 * for informational purpuses only and will show up in the result of
-	 * BifItems() as well as in the Describe() output.
-	 */
-	virtual bif_item_list CustomBifItems() const;
-
-	/**
-	 * Virtual method that can be overriden by derived class to load
-	 * files with extensions reported via SetFileExtension().
-	 *
-	 * This method will be called between InitPreScript() and
-	 * InitPostScript(), but with no further order or timing guaranteed.
-	 * It will be called once for each file encountered with of the
-	 * specificed extensions (i.e., duplicates are filtered out
-	 * automatically).
-	 *
-	 * @return True if the file was loaded successfuly, false if not. Bro
-	 * will abort in the latter case.
-	 */
-	virtual bool LoadFile(const char* file);
-
-	/**
-	 * Initializes the BiF items added with AddBifItem(). Internal method
-	 * that will be called by the manager at the right time.
-	 */
-	void InitBifs();
-
 	/**
 	 * Internal function adding an entry point for registering
 	 * auto-generated BiFs.
 	 */
 	void __AddBifInitFunction(bif_init_func c);
 
-private:
+protected:
-	typedef std::list<bif_init_func> bif_init_func_list;
+	friend class Manager;
 
-	const char* name;
-	const char* description;
-	const char* base_dir;
-	const char* sopath;
-	const char* extensions;
-	int version;
-	int api_version;
-	bool dynamic;
-
-	component_list components;
-	bif_item_list bif_items;
-	bif_init_func_list bif_inits;
-};
-
-/**
- * Class for hooking into script execution. An interpreter plugin can do
- * everything a normal plugin can, yet will also be interfaced to the script
- * interpreter for learning about, modidying, or potentially replacing
- * standard functionality.
- */
-class InterpreterPlugin : public Plugin {
-public:
 	/**
-	 * Constructor.
+	 * Registers and activates a component.
 	 *
-	 * @param priority Imposes an order on InterpreterPlugins in which
+	 * @param c The component. The method takes ownership.
-	 * they'll be chained. The higher the prioritu, the earlier a plugin
-	 * is called when the interpreter goes through the chain. */
-	InterpreterPlugin(int priority);
-
-	/**
-	 * Destructor.
 	 */
-	virtual ~InterpreterPlugin();
+	void AddComponent(Component* c);
 
 	/**
-	 * Returns the plugins priority.
+	 * Enables a hook. The corresponding virtual method will now be
+	 * called as Bro's processing proceeds. Note that enabling hooks can
+	 * have performance impaxct as many trigger frequently inside Bro's
+	 * main processing path.
+	 *
+	 * Note that hooks may be enabled/disabled dynamically at any time,
+	 * the output of Bro's \c -NN option will only reflect that state at
+	 * startup time; hence usually one should call this for a plugin's
+	 * hooks in either the plugin's ctor or in InitPreScript(). For
+	 * consistency with other parts of the API, there's a macro
+	 * PLUGIN_ENABLE_HOOK for use inside the ctor.
+	 *
+	 * @param hook The hook to enable.
+	 *
+	 * @param priority If multiple plugins enable the same hook, their
+	 * priorities determine the order in which they'll be executed, from
+	 * highest to lowest. If two plugins specify the same priority, order
+	 * is undefined.
 	 */
-	int Priority() const;
+	void EnableHook(HookType hook, int priority = 0);
 
 	/**
-	 * Callback for executing a function/event/hook. Whenever the script
+	 * Disables a hook. Bro will no longer call the corresponding virtual
-	 * interpreter is about to execution a function, it first gives all
+	 * method.
-	 * InterpreterPlugins a chance to handle the call (in the order of their
+	 *
-	 * priorities). A plugin can either just inspect the call, or replace it
+	 * @param hook The hook to disable.
-	 * (i.e., prevent the interpreter from executing it). In the latter case
+	 */
-	 * it must provide a matching return value.
+	void DisableHook(HookType hook);
+
+	/**
+	 * Returns a list of hooks that are currently enabled for the plugin,
+	 * along with their priorities.
+	 */
+	hook_list EnabledHooks() const;
+
+	/**
+	 * Virtual method that can be overriden by derived class to provide
+	 * information about further script-level elements that the plugin
+	 * provides on its own, i.e., outside of the standard mechanism
+	 * processing *.bif files automatically. The returned information is
+	 * for informational purposes only and will show up in the result of
+	 * BifItems() as well as in the Describe() output.
+	 *
+	 * \todo Do we need both this an AddBifItem()?
+	 */
+	virtual bif_item_list CustomBifItems() const;
+
+	// Hook functions.
+
+	/**
+	 * Hook into loading input files. This method will be called between
+	 * InitPreScript() and InitPostScript(), but with no further order or
+	 * timing guaranteed. It will be called once for each input file Bro
+	 * is about to load, either given on the command line or via @load
+	 * script directives. The hook can take over the file, in which case
+	 * Bro not further process it otherwise.
+	 *
+	 * @return 1 if the plugin took over the file and loaded it
+	 * successfully; 0 if the plugin took over the file but had trouble
+	 * loading it (Bro will abort in this case, the plugin should have
+	 * printed an error message); and -1 if the plugin wasn't interested
+	 * in the file at all.
+	 */
+	virtual int HookLoadFile(const char* file);
+
+	/**
+	 * Hook into executing a script-level function/event/hook. Whenever
+	 * the script interpreter is about to execution a function, it first
+	 * gives all plugins with this hook enabled a chance to handle the
+	 * call (in the order of their priorities). A plugin can either just
+	 * inspect the call, or replace it (i.e., prevent the interpreter
+	 * from executing it). In the latter case it must provide a matching
+	 * return value.
 	 *
 	 * The default implementation does never handle the call in any way.
- 	 *
+	 *
 	 * @param func The function being called.
 	 *
 	 * @param args The function arguments. The method can modify the list
@@ -412,55 +349,133 @@ public:
 	 * TYPE_ANY). If the plugin did not handle the call, it must return
 	 * null.
 	 */
-	virtual Val* CallFunction(const Func* func, val_list* args);
+	virtual Val* HookCallFunction(const Func* func, val_list* args);
-
-    /**
-     * Callback for raising an event. Whenever the script interpreter is
-     * about to queue an event for later execution, it first gives all
-     * InterpreterPlugins a chance to handle the queuing otherwise (in the
-     * order of their priorities). A plugin can either just inspect the
-     * event, or take it over (i.e., prevent the interpreter from queuing it
-     * it).
-     *
-	 * The default implementation does never handle the queuing in any way.
-     *
-     * @param event The even to be queued. The method can modify it in in
-     * place long as it ensures matching types and correct reference
-     * counting.
-     *
-     * @return True if the plugin took charge of the event; in that case it
-     * must have assumed ownership of the event and the intpreter will not do
-     * anything further with it. False otherwise.
-	 *
-     */
-	virtual bool QueueEvent(Event* event);
 
 	/**
-	 * Callback for updates in network time. This method will be called
+	 * Hook into raising events. Whenever the script interpreter is about
+	 * to queue an event for later execution, it first gives all plugins
+	 * with this hook enabled a chance to handle the queuing otherwise
+	 * (in the order of their priorities). A plugin can either just
+	 * inspect the event, or take it over (i.e., prevent the interpreter
+	 * from queuing it it).
+	 *
+	 * The default implementation does never handle the queuing in any
+	 * way.
+	 *
+	 * @param event The even to be queued. The method can modify it in in
+	 * place long as it ensures matching types and correct reference
+	 * counting.
+	 *
+	 * @return True if the plugin took charge of the event; in that case
+	 * it must have assumed ownership of the event and the intpreter will
+	 * not do anything further with it. False otherwise.
+	 */
+	virtual bool HookQueueEvent(Event* event);
+
+	/**
+	 * Hook intp event queue draining. This method will be called
+	 * whenever the event manager is draining its queue.
+	 */
+	virtual void HookDrainEvents();
+
+	/**
+	 * Hook for updates to network time. This method will be called
 	 * whenever network time is advanced.
 	 *
 	 * @param networkt_time The new network time.
 	 */
-	virtual void UpdateNetworkTime(double network_time);
+	virtual void HookUpdateNetworkTime(double network_time);
+
+	// Methods that are used internally primarily.
 
 	/**
-	 * Callback for event queue draining. This method will be called
+	 * Sets the plugins name.
-	 * whenever the event manager has drained it queue.
+	 *
+	 * This is used primarily internally; plugin code should pass the
+	 * name via the BRO_PLUGIN_BEGIN macro instead.
+	 *
+	 * @param name The name. Makes a copy internally.
 	 */
-	virtual void DrainEvents();
+	void SetName(const char* name);
 
 	/**
-	 * Disables interpreter hooking. The functionality of the Plugin base
+	 * Sets the plugin's textual description.
-	 * class remains available.
+	 *
+	 * This is used primarily internally; plugin code should pass the
+	 * name via the BRO_PLUGIN_DESCRIPTION macro instead.
+	 *
+	 * @param name The description. Makes a copy internally.
 	 */
-	void DisableInterpreterPlugin() const;
+	void SetDescription(const char* descr);
 
-	// Overridden from base class.
+	/**
-	virtual Type PluginType() const;
+	 * Sets the plugin's version.
+	 *
+	 * This is used primarily internally; plugin code should pass the
+	 * name via the BRO_PLUGIN_VERSION macro instead.
+	 *
+	 * @param version The version.
+	 */
+	void SetVersion(int version);
+
+	/**
+	 * Sets the API version the plugin requires.
+	 * BRO_PLUGIN_VERSION_BUILTIN indicates that it's a plugin linked in
+	 * statically.
+	 *
+	 * This is used primarily internally; plugins automatically set
+	 * either API version of the Bro they are compiled dynamically for,
+	 * or BRO_PLUGIN_VERSION_BUILTIN if they are linked in statically.
+	 *
+	 * @param version The version.
+	 */
+	void SetAPIVersion(int version);
+
+	/**
+	 * Marks the plugin as statically or dynamically linked.
+	 *
+	 * This is used primarily internally; plugins automatically set this
+	 * based on which way they are compiled.
+	 *
+	 * @param dynamic True if this is a dynamically linked plugin.
+	 */
+	void SetDynamicPlugin(bool dynamic);
+
+	/**
+	 * Sets the base directory and shared library path from which the
+	 * plugin was loaded.
+	 *
+	 * This is used primarily internally; plugins will have there
+	 * location set automatically.
+	 *
+	 * @param dir The plugin directory. The functions makes an internal
+	 * copy of string.
+	 *
+	 * @param sopath The full path the shared library loaded. The
+	 * functions makes an internal copy of string.
+	 */
+	void SetPluginLocation(const char* dir, const char* sopath);
 
 private:
-	int priority;
+	/**
+	 * Initializes the BiF items added with AddBifItem(). Internal method
+	 * that will be called by the manager at the right time.
+	 */
+	void InitBifs();
 
+	typedef std::list<bif_init_func> bif_init_func_list;
+
+	const char* name;
+	const char* description;
+	const char* base_dir;
+	const char* sopath;
+	int version;
+	int api_version;
+	bool dynamic;
+
+	component_list components;
+	bif_item_list bif_items;
+	bif_init_func_list bif_inits;
 };
 
 }

src/scan.l

@@ -581,7 +581,7 @@ YYLTYPE GetCurrentLocation()
 
 static int load_files(const char* orig_file)
 	{
-	int rc = plugin_mgr->TryLoadFile(orig_file);
+	int rc = PLUGIN_HOOK_WITH_RESULT(HOOK_LOAD_FILE, HookLoadFile(orig_file), -1);
 
 	if ( rc == 1 )
 		return 0; // A plugin took care of it, just skip.

src/util.h

@@ -213,7 +213,7 @@ extern void add_to_bro_path(const std::string& dir);
 
 extern const char* bro_magic_path();
 extern const char* bro_plugin_path();
-extern const char* bro_prefixes();
+extern std::string bro_prefixes();
 std::string dot_canon(std::string path, std::string file, std::string prefix = "");
 const char* normalize_path(const char* path);
 void get_script_subpath(const std::string& full_filename, const char** subpath);