negotiate explicitly registered IRC capabilities

docs/plugin-api-additions/caps.md

@@ -0,0 +1,35 @@
+# Script-supported capabilities
+
+`register_capability(name, userdata=None, connection_id=None)` returns a normal
+hook handle. Register before connecting/reconnecting. Core requests the name only
+if advertised in CAP LS or CAP NEW. Existing built-in requests remain enabled;
+SASL and STS registration is rejected so scripts cannot change authentication or
+transport policy through this API. None/-1 means any connection (zero is a valid
+connection ID). Names are lowercase ASCII alphanumerics plus - . / _, 1-200 bytes.
+Duplicate registrations do not duplicate requests for an advertised token.
+
+`unhook(handle)` or script/plugin unload removes future request ownership. It
+intentionally does not disable a capability already acknowledged on a live
+connection, because another plugin/core may depend on it. Registering after CAP
+LS does not retrospectively negotiate an already-advertised capability: reconnect
+or wait for CAP NEW. Core retains ownership of CAP END; this API does not extend
+SASL waiting or delay registration awaiting plugin-only CAP ACKs.
+
+`hook_capability(name, callback, userdata=None, priority=PRI_NORM)` independently
+observes negotiation through existing raw CAP hooks. Callback receives
+`(CapabilityEvent, userdata)` with name, subcommand, value, enabled, context and
+connection_id. LS/NEW mean advertised (`enabled=None`), ACK/LIST mean enabled
+(unless a negative ACK), NAK means rejected and DEL means removed. Callback
+returns are ignored so this observer cannot eat core negotiation. Existing raw
+hooks may still eat CAP before this hook according to their normal priorities.
+
+C: `zoitechat_register_capability(ph, name, flags, connection_id, userdata)`;
+flags=0, ID=-1 for any. Check get_info("api_plugin_caps") for "1" before using
+the appended Windows slot. Use existing server CAP hooks for notifications.
+Requests are split at complete token boundaries within the existing wire limit.
+
+```python
+registration = zoitechat.register_capability('draft/example')
+zoitechat.hook_capability('draft/example', lambda event, data:
+                         event.context.prnt('{}: {}'.format(event.subcommand, event.enabled)))
+```

plugins/python/_zoitechat_caps.py

@@ -0,0 +1,64 @@
+"""Script-owned capability requests and structured negotiation observations."""
+from collections import namedtuple
+import operator
+import _zoitechat as api
+from _zoitechat_embedded import ffi, lib
+
+__all__ = ['CapabilityEvent', 'register_capability', 'hook_capability']
+CapabilityEvent = namedtuple('CapabilityEvent',
+                            'name subcommand value enabled context connection_id')
+
+
+def register_capability(name, userdata=None, connection_id=None):
+    """Request an advertised capability on next negotiation; unhook releases ownership."""
+    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(None, userdata)
+    handle = lib.zoitechat_register_capability(lib.ph, name.encode(), 0,
+                                              connection_id, hook.handle)
+    if handle == ffi.NULL:
+        hook.is_unload = True
+        plugin.remove_hook(id(hook))
+        raise ValueError('invalid capability name, reserved capability or connection ID')
+    hook.zoitechat_hook = handle
+    return id(hook)
+
+
+def hook_capability(name, callback, userdata=None, priority=api.PRI_NORM):
+    """Observe LS/NEW/ACK/NAK/DEL/LIST; this hook does not itself request the capability."""
+    if not callable(callback):
+        raise TypeError('callback must be callable')
+
+    def dispatch(word, word_eol, data):
+        if not word_eol:
+            return api.EAT_NONE
+        line = word_eol[0]
+        if line.startswith(':'):
+            unused, separator, line = line.partition(' ')
+        parts = line.split(' ', 3)
+        if len(parts) != 4 or parts[0].upper() != 'CAP':
+            return api.EAT_NONE
+        subcommand, tokens = parts[2].upper(), parts[3]
+        if subcommand not in ('LS', 'NEW', 'ACK', 'NAK', 'DEL', 'LIST'):
+            return api.EAT_NONE
+        if tokens.startswith('* '):
+            tokens = tokens[2:]
+        tokens = tokens.lstrip(':')
+        for token in tokens.split():
+            negative = token.startswith('-')
+            cap, equals, value = token.lstrip('-').partition('=')
+            if cap != name:
+                continue
+            enabled = None
+            if subcommand in ('ACK', 'LIST'):
+                enabled = not negative
+            elif subcommand in ('DEL', 'NAK'):
+                enabled = False
+            event = CapabilityEvent(cap, subcommand, value if equals else None,
+                                    enabled, api.get_context(), api.get_prefs('id'))
+            callback(event, data)
+        return api.EAT_NONE  # observing CAP must not suppress core negotiation
+
+    return api.hook_server('CAP', dispatch, userdata, priority)

src/common/inbound.c

@@ -41,6 +41,8 @@
 #include "network.h"
 #include "notify.h"
 #include "outbound.h"
+#include <gmodule.h>
+#include "plugin.h"
 #include "inbound.h"
 #include "server.h"
 #include "servlist.h"
@@ -1962,10 +1964,58 @@ inbound_cap_ack (server *serv, char *nick, char *extensions,
 	inbound_toggle_caps (serv, extensions, TRUE);
 }
 
+/* Split requests only at token boundaries, including plugin-added names. */
+static void
+inbound_cap_request_append (server *serv, char *buffer, gsize size,
+                            const char *name, time_t timestamp)
+{
+	if (strlen (buffer) + strlen (name) + 1 >= size)
+	{
+		EMIT_SIGNAL_TIMESTAMP (XP_TE_CAPREQ, serv->server_session,
+			buffer + 9, NULL, NULL, NULL, 0, timestamp);
+		tcp_sendf (serv, "%s\r\n", g_strchomp (buffer));
+		g_strlcpy (buffer, "CAP REQ :", size);
+	}
+	g_strlcat (buffer, name, size);
+	g_strlcat (buffer, " ", size);
+}
+
+static void
+inbound_plugin_cap_new (server *serv, const char *extensions, time_t timestamp)
+{
+	char buffer[500] = "CAP REQ :";
+	char **tokens = g_strsplit (extensions, " ", 0);
+	GHashTable *seen = g_hash_table_new (g_str_hash, g_str_equal);
+	int i;
+	gboolean requested = FALSE;
+	for (i = 0; tokens[i]; i++)
+	{
+		char *value = strchr (tokens[i], '=');
+		if (value)
+			*value = '\0';
+		if (plugin_requests_capability (serv, tokens[i]) &&
+			!g_hash_table_contains (seen, tokens[i]))
+		{
+			g_hash_table_add (seen, tokens[i]);
+			inbound_cap_request_append (serv, buffer, sizeof (buffer), tokens[i], timestamp);
+			requested = TRUE;
+		}
+	}
+	if (requested)
+	{
+		EMIT_SIGNAL_TIMESTAMP (XP_TE_CAPREQ, serv->server_session,
+			buffer + 9, NULL, NULL, NULL, 0, timestamp);
+		tcp_sendf (serv, "%s\r\n", g_strchomp (buffer));
+	}
+	g_hash_table_destroy (seen);
+	g_strfreev (tokens);
+}
+
 void
 inbound_cap_new (server *serv, char *nick, char *extensions,
 					 const message_tags_data *tags_data)
 {
+	gboolean sts_upgrade_triggered = FALSE;
 	if (extensions)
 	{
 		char **tokens = g_strsplit (extensions, " ", 0);
@@ -1977,7 +2027,7 @@ inbound_cap_new (server *serv, char *nick, char *extensions,
 
 			if (!g_strcmp0 (parts[0], "sts") && parts[1] && parts[1][0])
 			{
-				sts_handle_capability (serv, parts[1]);
+				sts_upgrade_triggered |= sts_handle_capability (serv, parts[1]);
 			}
 
 			g_strfreev (parts);
@@ -1986,6 +2036,9 @@ inbound_cap_new (server *serv, char *nick, char *extensions,
 		g_strfreev (tokens);
 	}
 
+	if (extensions && !sts_upgrade_triggered)
+		inbound_plugin_cap_new (serv, extensions, tags_data->timestamp);
+
 	EMIT_SIGNAL_TIMESTAMP (XP_TE_CAPACK, serv->server_session, nick, extensions,
 								  NULL, NULL, 0, tags_data->timestamp);
 
@@ -2116,6 +2169,7 @@ inbound_cap_ls (server *serv, char *nick, char *extensions_str,
 	gboolean want_cap = FALSE; /* format the CAP REQ string based on previous capabilities being requested or not */
 	gboolean sts_upgrade_triggered = FALSE;
 	char **extensions;
+	GString *requests = g_string_new ("");
 	int i;
 
 	if (g_str_has_prefix (extensions_str, "* "))
@@ -2181,7 +2235,7 @@ inbound_cap_ls (server *serv, char *nick, char *extensions_str,
 			}
 			want_cap = TRUE;
 			serv->waiting_on_sasl = TRUE;
-			g_strlcat (buffer, "sasl ", sizeof(buffer));
+			g_string_append (requests, "sasl ");
 			continue;
 		}
 
@@ -2189,28 +2243,44 @@ inbound_cap_ls (server *serv, char *nick, char *extensions_str,
 		{
 			if (!g_strcmp0 (extension, supported_caps[x]))
 			{
-				g_strlcat (buffer, extension, sizeof(buffer));
-				g_strlcat (buffer, " ", sizeof(buffer));
+				g_string_append (requests, extension);
+				g_string_append_c (requests, ' ');
 				want_cap = TRUE;
+				break;
 			}
 		}
+		if (x == G_N_ELEMENTS (supported_caps) && plugin_requests_capability (serv, extension))
+		{
+			g_string_append (requests, extension);
+			g_string_append_c (requests, ' ');
+			want_cap = TRUE;
+		}
+
 	}
 
 	g_strfreev (extensions);
 
 	if (sts_upgrade_triggered)
 	{
+		g_string_free (requests, TRUE);
 		return;
 	}
 
 	if (want_cap)
 	{
+		char **tokens = g_strsplit (requests->str, " ", 0);
+		/* Defer every batch until STS has decided whether to reconnect. */
+		for (i = 0; tokens[i]; i++)
+			if (tokens[i][0])
+				inbound_cap_request_append (serv, buffer, sizeof (buffer), tokens[i], tags_data->timestamp);
+		g_strfreev (tokens);
 		/* buffer + 9 = emit buffer without "CAP REQ :" */
 		EMIT_SIGNAL_TIMESTAMP (XP_TE_CAPREQ, serv->server_session,
 									  buffer + 9, NULL, NULL, NULL, 0,
 									  tags_data->timestamp);
 		tcp_sendf (serv, "%s\r\n", g_strchomp (buffer));
 	}
+	g_string_free (requests, TRUE);
 	if (!serv->waiting_on_sasl && !serv->waiting_on_cap)
 	{
 		/* if we use SASL, CAP END is dealt via raw numerics */

src/common/plugin.c

@@ -99,6 +99,7 @@ struct _zoitechat_hook
 	int tag;				/* for timers & FDs only */
 	int type;			/* HOOK_* */
 	int pri;	/* fd */	/* priority / fd for HOOK_FD only */
+	int cap_connection_id;
 	int connection_filter;
 	char *channel_filter;
 	gboolean context_filtered;
@@ -147,6 +148,7 @@ enum
 	HOOK_TIMER        = 1 << 5, /* timeouts */
 	HOOK_FD           = 1 << 6, /* sockets & fds */
 	HOOK_PRINT_AFTER  = 1 << 8, /* opt-in post-display observers */
+	HOOK_CAPABILITY   = 1 << 9, /* script-owned CAP requests */
 	HOOK_DELETED      = 1 << 7  /* marked for deletion */
 };
 
@@ -355,6 +357,7 @@ 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_register_capability = zoitechat_register_capability;
 		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;
@@ -1114,6 +1117,39 @@ zoitechat_hook_print_filtered (zoitechat_plugin *ph, const char *name, int pri,
 		HOOK_PRINT_ATTRS, callback, userdata);
 }
 
+zoitechat_hook *
+zoitechat_register_capability (zoitechat_plugin *ph, const char *name, int flags,
+                              int connection_id, void *userdata)
+{
+	const unsigned char *p;
+	zoitechat_hook *hook;
+	if (flags != 0 || connection_id < -1 || !name || !name[0] || strlen (name) > 200 ||
+		strcmp (name, "sasl") == 0 || strcmp (name, "sts") == 0)
+		return NULL; /* authentication and transport policy belong to core */
+	for (p = (const unsigned char *)name; *p; p++)
+		if (!g_ascii_islower (*p) && !g_ascii_isdigit (*p) &&
+			*p != '-' && *p != '.' && *p != '/' && *p != '_')
+			return NULL;
+	hook = plugin_add_hook (ph, HOOK_CAPABILITY, 0, name, NULL, NULL, 0, userdata);
+	hook->cap_connection_id = connection_id;
+	return hook;
+}
+
+gboolean
+plugin_requests_capability (server *serv, const char *name)
+{
+	GSList *entry;
+	for (entry = hook_list; entry; entry = entry->next)
+	{
+		zoitechat_hook *hook = entry->data;
+		if (hook && hook->type == HOOK_CAPABILITY &&
+			(hook->cap_connection_id == -1 || hook->cap_connection_id == serv->id) &&
+			strcmp (hook->name, name) == 0)
+			return TRUE;
+	}
+	return FALSE;
+}
+
 zoitechat_hook *
 zoitechat_hook_command (zoitechat_plugin *ph, const char *name, int pri,
 						  zoitechat_cmd_cb *callb, const char *help_text, void *userdata)
@@ -1289,6 +1325,9 @@ zoitechat_get_info (zoitechat_plugin *ph, const char *id)
 	if (strcmp (id, "api_context_filters") == 0)
 		return "1";
 
+	if (strcmp (id, "api_plugin_caps") == 0)
+		return "1";
+
 	hash = str_hash (id);
 	/* do the session independant ones first */
 	switch (hash)

src/common/plugin.h

@@ -183,6 +183,7 @@ int plugin_emit_command (session *sess, char *name, char *word[], char *word_eol
 int plugin_emit_server (session *sess, char *name, char *word[], char *word_eol[],
 						time_t server_time);
 int plugin_emit_print (session *sess, char *word[], time_t server_time);
+gboolean plugin_requests_capability (server *serv, const char *name);
 void plugin_emit_print_after (session *sess, char *word[], time_t server_time);
 int plugin_emit_dummy_print (session *sess, char *name);
 int plugin_emit_keypress (session *sess, unsigned int state, unsigned int keyval, gunichar key);

src/common/zoitechat-plugin.h

@@ -222,6 +222,10 @@ zoitechat_hook *zoitechat_hook_print_filtered (zoitechat_plugin *ph,
     int (*callback) (char *word[], zoitechat_event_attrs *attrs, void *userdata),
     void *userdata);
 
+/* api_plugin_caps=1: register before CAP LS; flags=0, connection_id=-1 for any. */
+zoitechat_hook *zoitechat_register_capability (zoitechat_plugin *ph,
+    const char *name, int flags, int connection_id, void *userdata);
+
 zoitechat_hook *
 zoitechat_hook_command (zoitechat_plugin *ph,
 		    const char *name,
@@ -441,6 +445,7 @@ 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_register_capability ((ZOITECHAT_PLUGIN_HANDLE)->zoitechat_register_capability)
 #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)