filter hooks by connection and context in core

docs/plugin-api-additions/filters.md

@@ -0,0 +1,24 @@
+# Core-filtered hooks
+
+Python: `hook_server_filtered(name, callback, userdata=None, priority=PRI_NORM,
+connection_id=None, channel=None)` and `hook_print_filtered(...)`.
+Callbacks match the existing attrs variants: `(word, word_eol, userdata, attrs)`.
+The connection ID distinguishes duplicate names; None/-1 means any connection
+(including connection ID zero). A channel restriction uses that connection's
+IRC comparator. None means any context; an empty string is an exact restriction.
+
+C: the corresponding zoitechat_hook_*_filtered functions accept
+`(ph, name, pri, flags, connection_id, channel, callback, userdata)`;
+flags=0, ID=-1 for any and NULL channel for any. Check
+`get_info("api_context_filters")` for "1" before accessing the new Windows slots.
+
+Filtering takes place before Python/interpreter entry. Existing unrestricted
+hooks, priority, EAT semantics and unload/unhook handling are unchanged.
+Filters refer to the core-selected context, not an IRC target parsed from the
+line: unknown queries/channels can still have a server-tab context, and QUIT
+has its usual single server-hook context. Connection IDs last only this process.
+
+```python
+zoitechat.hook_print_filtered('Channel Message', callback,
+                             connection_id=zoitechat.get_prefs('id'), channel='#zoitechat')
+```

plugins/python/_zoitechat_filters.py

@@ -0,0 +1,36 @@
+"""Context restrictions evaluated by core before entering Python."""
+import operator
+import _zoitechat as api
+from _zoitechat_embedded import ffi, lib
+
+__all__ = ['hook_server_filtered', 'hook_print_filtered']
+
+
+def _register(name, callback, userdata, priority, connection_id, channel, server):
+    if not callable(callback):
+        raise TypeError('callback must be callable')
+    connection_id = -1 if connection_id is None else operator.index(connection_id)
+    if connection_id < -1 or connection_id > 2147483647:
+        raise ValueError('connection_id must fit the C API; -1 means any')
+    plugin = api.__get_current_plugin()
+    hook = plugin.add_hook(callback, userdata)
+    register = lib.zoitechat_hook_server_filtered if server else lib.zoitechat_hook_print_filtered
+    dispatch = lib._on_server_attrs_hook if server else lib._on_print_attrs_hook
+    handle = register(lib.ph, name.encode(), priority, 0, connection_id,
+                      ffi.NULL if channel is None else channel.encode(), dispatch, hook.handle)
+    if handle == ffi.NULL:
+        hook.is_unload = True
+        plugin.remove_hook(id(hook))
+        raise RuntimeError('unable to install filtered hook')
+    hook.zoitechat_hook = handle
+    return id(hook)
+
+
+def hook_server_filtered(name, callback, userdata=None, priority=api.PRI_NORM,
+                         connection_id=None, channel=None):
+    return _register(name, callback, userdata, priority, connection_id, channel, True)
+
+
+def hook_print_filtered(name, callback, userdata=None, priority=api.PRI_NORM,
+                        connection_id=None, channel=None):
+    return _register(name, callback, userdata, priority, connection_id, channel, False)

src/common/plugin.c

@@ -99,6 +99,9 @@ struct _zoitechat_hook
 	int tag;				/* for timers & FDs only */
 	int type;			/* HOOK_* */
 	int pri;	/* fd */	/* priority / fd for HOOK_FD only */
+	int connection_filter;
+	char *channel_filter;
+	gboolean context_filtered;
 };
 
 struct _zoitechat_list
@@ -352,6 +355,8 @@ plugin_add (session *sess, char *filename, void *handle, void *init_func,
 		pl->zoitechat_emit_print_attrs = zoitechat_emit_print_attrs;
 		pl->zoitechat_event_attrs_create = zoitechat_event_attrs_create;
 		pl->zoitechat_event_attrs_free = zoitechat_event_attrs_free;
+		pl->zoitechat_hook_server_filtered = zoitechat_hook_server_filtered;
+		pl->zoitechat_hook_print_filtered = zoitechat_hook_print_filtered;
 		pl->zoitechat_hook_print_after = zoitechat_hook_print_after;
 
 		/* run zoitechat_plugin_init, if it returns 0, close the plugin */
@@ -623,6 +628,15 @@ plugin_hook_run (session *sess, char *name, char *word[], char *word_eol[],
 
 		hook = list->data;
 		next = list->next;
+		if (hook->context_filtered &&
+			(!is_session (sess) ||
+			 (hook->connection_filter != -1 && hook->connection_filter != sess->server->id) ||
+			 (hook->channel_filter && sess->server->p_cmp (hook->channel_filter, sess->channel))))
+		{
+			list = next;
+			continue; /* filter in C before entering an interpreter */
+		}
+
 		if (type == HOOK_PRINT_AFTER && hook->tag)
 		{
 			list = next;
@@ -1052,6 +1066,8 @@ zoitechat_unhook (zoitechat_plugin *ph, zoitechat_hook *hook)
 
 	g_free (hook->name);	/* NULL for timers & fds */
 	g_free (hook->help_text);	/* NULL for non-commands */
+	g_free (hook->channel_filter);
+	hook->channel_filter = NULL;
 
 	return hook->userdata;
 }
@@ -1065,6 +1081,39 @@ zoitechat_hook_print_after (zoitechat_plugin *ph, const char *name, int pri,
 	return plugin_add_hook (ph, HOOK_PRINT_AFTER, pri, name, NULL, callback, 0, userdata);
 }
 
+static zoitechat_hook *
+plugin_add_filtered_hook (zoitechat_plugin *ph, const char *name, int pri,
+                         int flags, int connection_id, const char *channel,
+                         int type, void *callback, void *userdata)
+{
+	zoitechat_hook *hook;
+	if (flags != 0 || connection_id < -1 || !name || !callback)
+		return NULL;
+	hook = plugin_add_hook (ph, type, pri, name, NULL, callback, 0, userdata);
+	hook->context_filtered = TRUE;
+	hook->connection_filter = connection_id;
+	hook->channel_filter = g_strdup (channel);
+	return hook;
+}
+
+zoitechat_hook *
+zoitechat_hook_server_filtered (zoitechat_plugin *ph, const char *name, int pri,
+                               int flags, int connection_id, const char *channel,
+                               zoitechat_serv_attrs_cb *callback, void *userdata)
+{
+	return plugin_add_filtered_hook (ph, name, pri, flags, connection_id, channel,
+		HOOK_SERVER_ATTRS, callback, userdata);
+}
+
+zoitechat_hook *
+zoitechat_hook_print_filtered (zoitechat_plugin *ph, const char *name, int pri,
+                              int flags, int connection_id, const char *channel,
+                              zoitechat_print_attrs_cb *callback, void *userdata)
+{
+	return plugin_add_filtered_hook (ph, name, pri, flags, connection_id, channel,
+		HOOK_PRINT_ATTRS, callback, userdata);
+}
+
 zoitechat_hook *
 zoitechat_hook_command (zoitechat_plugin *ph, const char *name, int pri,
 						  zoitechat_cmd_cb *callb, const char *help_text, void *userdata)
@@ -1237,6 +1286,9 @@ zoitechat_get_info (zoitechat_plugin *ph, const char *id)
 	if (strcmp (id, "api_hook_print_after") == 0)
 		return "1";
 
+	if (strcmp (id, "api_context_filters") == 0)
+		return "1";
+
 	hash = str_hash (id);
 	/* do the session independant ones first */
 	switch (hash)

src/common/zoitechat-plugin.h

@@ -212,6 +212,16 @@ zoitechat_hook *zoitechat_hook_print_after (zoitechat_plugin *ph,
     int (*callback) (char *word[], zoitechat_event_attrs *attrs, void *userdata),
     void *userdata);
 
+/* api_context_filters=1: connection_id -1 is any; NULL channel is any. */
+zoitechat_hook *zoitechat_hook_server_filtered (zoitechat_plugin *ph,
+    const char *name, int pri, int flags, int connection_id, const char *channel,
+    int (*callback) (char *word[], char *word_eol[], zoitechat_event_attrs *attrs, void *userdata),
+    void *userdata);
+zoitechat_hook *zoitechat_hook_print_filtered (zoitechat_plugin *ph,
+    const char *name, int pri, int flags, int connection_id, const char *channel,
+    int (*callback) (char *word[], zoitechat_event_attrs *attrs, void *userdata),
+    void *userdata);
+
 zoitechat_hook *
 zoitechat_hook_command (zoitechat_plugin *ph,
 		    const char *name,
@@ -431,6 +441,8 @@ zoitechat_pluginpref_list (zoitechat_plugin *ph,
 #define zoitechat_hook_server ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_server)
 #define zoitechat_hook_server_attrs ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_server_attrs)
 #define zoitechat_hook_print ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_print)
+#define zoitechat_hook_server_filtered ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_server_filtered)
+#define zoitechat_hook_print_filtered ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_print_filtered)
 #define zoitechat_hook_print_after ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_print_after)
 #define zoitechat_hook_print_attrs ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_print_attrs)
 #define zoitechat_hook_timer ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_hook_timer)