2 * Asterisk -- An open source telephony toolkit.
4 * Copyright (c) 2004-2006 Tilghman Lesher <app_stack_v003@the-tilghman.com>.
6 * This code is released by the author with no restrictions on usage.
8 * See http://www.asterisk.org for more information about
9 * the Asterisk project. Please do not directly contact
10 * any of the maintainers of this project for assistance;
11 * the project provides a web site, mailing lists and IRC
12 * channels for your use.
14 * This program is free software, distributed under the terms of
15 * the GNU General Public License Version 2. See the LICENSE file
16 * at the top of the source tree.
21 * \brief Stack applications Gosub, Return, etc.
23 * \author Tilghman Lesher <app_stack_v003@the-tilghman.com>
25 * \ingroup applications
34 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
36 #include "asterisk/pbx.h"
37 #include "asterisk/module.h"
38 #include "asterisk/app.h"
39 #include "asterisk/manager.h"
40 #include "asterisk/channel.h"
41 #include "asterisk/agi.h"
44 <application name="Gosub" language="en_US">
46 Jump to label, saving return address.
49 <parameter name="context" />
50 <parameter name="exten" />
51 <parameter name="priority" required="true" hasparams="optional">
52 <argument name="arg1" multiple="true" required="true" />
53 <argument name="argN" />
57 <para>Jumps to the label specified, saving the return address.</para>
60 <ref type="application">GosubIf</ref>
61 <ref type="application">Macro</ref>
62 <ref type="application">Goto</ref>
63 <ref type="application">Return</ref>
64 <ref type="application">StackPop</ref>
67 <application name="GosubIf" language="en_US">
69 Conditionally jump to label, saving return address.
72 <parameter name="condition" required="true" />
73 <parameter name="destination" required="true" argsep=":">
74 <argument name="labeliftrue" hasparams="optional">
75 <argument name="arg1" required="true" multiple="true" />
76 <argument name="argN" />
78 <argument name="labeliffalse" hasparams="optional">
79 <argument name="arg1" required="true" multiple="true" />
80 <argument name="argN" />
85 <para>If the condition is true, then jump to labeliftrue. If false, jumps to
86 labeliffalse, if specified. In either case, a jump saves the return point
87 in the dialplan, to be returned to with a Return.</para>
90 <ref type="application">Gosub</ref>
91 <ref type="application">Return</ref>
92 <ref type="application">MacroIf</ref>
93 <ref type="function">IF</ref>
94 <ref type="application">GotoIf</ref>
97 <application name="Return" language="en_US">
99 Return from gosub routine.
102 <parameter name="value">
103 <para>Return value.</para>
107 <para>Jumps to the last label on the stack, removing it. The return <replaceable>value</replaceable>, if
108 any, is saved in the channel variable <variable>GOSUB_RETVAL</variable>.</para>
111 <ref type="application">Gosub</ref>
112 <ref type="application">StackPop</ref>
115 <application name="StackPop" language="en_US">
117 Remove one address from gosub stack.
121 <para>Removes last label on the stack, discarding it.</para>
124 <ref type="application">Return</ref>
125 <ref type="application">Gosub</ref>
128 <function name="LOCAL" language="en_US">
130 Manage variables local to the gosub stack frame.
133 <parameter name="varname" required="true" />
136 <para>Read and write a variable local to the gosub stack frame, once we Return() it will be lost
137 (or it will go back to whatever value it had before the Gosub()).</para>
140 <ref type="application">Gosub</ref>
141 <ref type="application">GosubIf</ref>
142 <ref type="application">Return</ref>
145 <function name="LOCAL_PEEK" language="en_US">
147 Retrieve variables hidden by the local gosub stack frame.
150 <parameter name="n" required="true" />
151 <parameter name="varname" required="true" />
154 <para>Read a variable <replaceable>varname</replaceable> hidden by
155 <replaceable>n</replaceable> levels of gosub stack frames. Note that ${LOCAL_PEEK(0,foo)}
156 is the same as ${foo}, since the value of <replaceable>n</replaceable> peeks under 0 levels of
157 stack frames; in other words, 0 is the current level. If <replaceable>n</replaceable> exceeds
158 the available number of stack frames, then an empty string is returned.</para>
161 <ref type="application">Gosub</ref>
162 <ref type="application">GosubIf</ref>
163 <ref type="application">Return</ref>
168 static const char *app_gosub = "Gosub";
169 static const char *app_gosubif = "GosubIf";
170 static const char *app_return = "Return";
171 static const char *app_pop = "StackPop";
173 static void gosub_free(void *data);
175 static struct ast_datastore_info stack_info = {
177 .destroy = gosub_free,
180 struct gosub_stack_frame {
181 AST_LIST_ENTRY(gosub_stack_frame) entries;
182 /* 100 arguments is all that we support anyway, but this will handle up to 255 */
183 unsigned char arguments;
184 struct varshead varshead;
190 static int frame_set_var(struct ast_channel *chan, struct gosub_stack_frame *frame, const char *var, const char *value)
192 struct ast_var_t *variables;
195 /* Does this variable already exist? */
196 AST_LIST_TRAVERSE(&frame->varshead, variables, entries) {
197 if (!strcmp(var, ast_var_name(variables))) {
203 if (!ast_strlen_zero(value)) {
205 variables = ast_var_assign(var, "");
206 AST_LIST_INSERT_HEAD(&frame->varshead, variables, entries);
207 pbx_builtin_pushvar_helper(chan, var, value);
209 pbx_builtin_setvar_helper(chan, var, value);
211 manager_event(EVENT_FLAG_DIALPLAN, "VarSet",
213 "Variable: LOCAL(%s)\r\n"
216 chan->name, var, value, chan->uniqueid);
221 static void gosub_release_frame(struct ast_channel *chan, struct gosub_stack_frame *frame)
223 struct ast_var_t *vardata;
225 /* If chan is not defined, then we're calling it as part of gosub_free,
226 * and the channel variables will be deallocated anyway. Otherwise, we're
227 * just releasing a single frame, so we need to clean up the arguments for
228 * that frame, so that we re-expose the variables from the previous frame
229 * that were hidden by this one.
231 while ((vardata = AST_LIST_REMOVE_HEAD(&frame->varshead, entries))) {
233 pbx_builtin_setvar_helper(chan, ast_var_name(vardata), NULL);
234 ast_var_delete(vardata);
240 static struct gosub_stack_frame *gosub_allocate_frame(const char *context, const char *extension, int priority, unsigned char arguments)
242 struct gosub_stack_frame *new = NULL;
243 int len_extension = strlen(extension), len_context = strlen(context);
245 if ((new = ast_calloc(1, sizeof(*new) + 2 + len_extension + len_context))) {
246 AST_LIST_HEAD_INIT_NOLOCK(&new->varshead);
247 strcpy(new->extension, extension);
248 new->context = new->extension + len_extension + 1;
249 strcpy(new->context, context);
250 new->priority = priority;
251 new->arguments = arguments;
256 static void gosub_free(void *data)
258 AST_LIST_HEAD(, gosub_stack_frame) *oldlist = data;
259 struct gosub_stack_frame *oldframe;
260 AST_LIST_LOCK(oldlist);
261 while ((oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries))) {
262 gosub_release_frame(NULL, oldframe);
264 AST_LIST_UNLOCK(oldlist);
265 AST_LIST_HEAD_DESTROY(oldlist);
269 static int pop_exec(struct ast_channel *chan, void *data)
271 struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
272 struct gosub_stack_frame *oldframe;
273 AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
276 ast_log(LOG_WARNING, "%s called with no gosub stack allocated.\n", app_pop);
280 oldlist = stack_store->data;
281 AST_LIST_LOCK(oldlist);
282 oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries);
283 AST_LIST_UNLOCK(oldlist);
286 gosub_release_frame(chan, oldframe);
288 ast_debug(1, "%s called with an empty gosub stack\n", app_pop);
293 static int return_exec(struct ast_channel *chan, void *data)
295 struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
296 struct gosub_stack_frame *oldframe;
297 AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
301 ast_log(LOG_ERROR, "Return without Gosub: stack is unallocated\n");
305 oldlist = stack_store->data;
306 AST_LIST_LOCK(oldlist);
307 oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries);
308 AST_LIST_UNLOCK(oldlist);
311 ast_log(LOG_ERROR, "Return without Gosub: stack is empty\n");
315 ast_explicit_goto(chan, oldframe->context, oldframe->extension, oldframe->priority);
316 gosub_release_frame(chan, oldframe);
318 /* Set a return value, if any */
319 pbx_builtin_setvar_helper(chan, "GOSUB_RETVAL", S_OR(retval, ""));
323 static int gosub_exec(struct ast_channel *chan, void *data)
325 struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
326 AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
327 struct gosub_stack_frame *newframe;
328 char argname[15], *tmp = ast_strdupa(data), *label, *endparen;
330 AST_DECLARE_APP_ARGS(args2,
331 AST_APP_ARG(argval)[100];
334 if (ast_strlen_zero(data)) {
335 ast_log(LOG_ERROR, "%s requires an argument: %s([[context,]exten,]priority[(arg1[,...][,argN])])\n", app_gosub, app_gosub);
340 ast_debug(1, "Channel %s has no datastore, so we're allocating one.\n", chan->name);
341 stack_store = ast_datastore_alloc(&stack_info, NULL);
343 ast_log(LOG_ERROR, "Unable to allocate new datastore. Gosub will fail.\n");
347 oldlist = ast_calloc(1, sizeof(*oldlist));
349 ast_log(LOG_ERROR, "Unable to allocate datastore list head. Gosub will fail.\n");
350 ast_datastore_free(stack_store);
354 stack_store->data = oldlist;
355 AST_LIST_HEAD_INIT(oldlist);
356 ast_channel_datastore_add(chan, stack_store);
359 /* Separate the arguments from the label */
360 /* NOTE: you cannot use ast_app_separate_args for this, because '(' cannot be used as a delimiter. */
361 label = strsep(&tmp, "(");
363 endparen = strrchr(tmp, ')');
367 ast_log(LOG_WARNING, "Ouch. No closing paren: '%s'?\n", (char *)data);
368 AST_STANDARD_APP_ARGS(args2, tmp);
372 /* Create the return address, but don't save it until we know that the Gosub destination exists */
373 newframe = gosub_allocate_frame(chan->context, chan->exten, chan->priority + 1, args2.argc);
378 if (ast_parseable_goto(chan, label)) {
379 ast_log(LOG_ERROR, "Gosub address is invalid: '%s'\n", (char *)data);
384 /* Now that we know for certain that we're going to a new location, set our arguments */
385 for (i = 0; i < args2.argc; i++) {
386 snprintf(argname, sizeof(argname), "ARG%d", i + 1);
387 frame_set_var(chan, newframe, argname, args2.argval[i]);
388 ast_debug(1, "Setting '%s' to '%s'\n", argname, args2.argval[i]);
390 snprintf(argname, sizeof(argname), "%d", args2.argc);
391 frame_set_var(chan, newframe, "ARGC", argname);
393 /* And finally, save our return address */
394 oldlist = stack_store->data;
395 AST_LIST_LOCK(oldlist);
396 AST_LIST_INSERT_HEAD(oldlist, newframe, entries);
397 AST_LIST_UNLOCK(oldlist);
402 static int gosubif_exec(struct ast_channel *chan, void *data)
406 AST_DECLARE_APP_ARGS(cond,
410 AST_DECLARE_APP_ARGS(label,
412 AST_APP_ARG(iffalse);
415 if (ast_strlen_zero(data)) {
416 ast_log(LOG_WARNING, "GosubIf requires an argument: GosubIf(cond?label1(args):label2(args)\n");
420 args = ast_strdupa(data);
421 AST_NONSTANDARD_APP_ARGS(cond, args, '?');
422 if (cond.argc != 2) {
423 ast_log(LOG_WARNING, "GosubIf requires an argument: GosubIf(cond?label1(args):label2(args)\n");
427 AST_NONSTANDARD_APP_ARGS(label, cond.labels, ':');
429 if (pbx_checkcondition(cond.ition)) {
430 if (!ast_strlen_zero(label.iftrue))
431 res = gosub_exec(chan, label.iftrue);
432 } else if (!ast_strlen_zero(label.iffalse)) {
433 res = gosub_exec(chan, label.iffalse);
439 static int local_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
441 struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
442 AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
443 struct gosub_stack_frame *frame;
444 struct ast_var_t *variables;
449 oldlist = stack_store->data;
450 AST_LIST_LOCK(oldlist);
451 frame = AST_LIST_FIRST(oldlist);
452 AST_LIST_TRAVERSE(&frame->varshead, variables, entries) {
453 if (!strcmp(data, ast_var_name(variables))) {
455 ast_channel_lock(chan);
456 tmp = pbx_builtin_getvar_helper(chan, data);
457 ast_copy_string(buf, S_OR(tmp, ""), len);
458 ast_channel_unlock(chan);
462 AST_LIST_UNLOCK(oldlist);
466 static int local_write(struct ast_channel *chan, const char *cmd, char *var, const char *value)
468 struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
469 AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
470 struct gosub_stack_frame *frame;
473 ast_log(LOG_ERROR, "Tried to set LOCAL(%s), but we aren't within a Gosub routine\n", var);
477 oldlist = stack_store->data;
478 AST_LIST_LOCK(oldlist);
479 frame = AST_LIST_FIRST(oldlist);
482 frame_set_var(chan, frame, var, value);
484 AST_LIST_UNLOCK(oldlist);
489 static struct ast_custom_function local_function = {
491 .write = local_write,
495 static int peek_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
498 struct ast_var_t *variables;
499 AST_DECLARE_APP_ARGS(args,
505 ast_log(LOG_ERROR, "LOCAL_PEEK must be called on an active channel\n");
509 AST_STANDARD_APP_ARGS(args, data);
513 ast_channel_lock(chan);
514 AST_LIST_TRAVERSE(&chan->varshead, variables, entries) {
515 if (!strcmp(args.name, ast_var_name(variables)) && ++found > n) {
516 ast_copy_string(buf, ast_var_value(variables), len);
520 ast_channel_unlock(chan);
524 static struct ast_custom_function peek_function = {
525 .name = "LOCAL_PEEK",
526 .synopsis = "Peeks at variables within the variable stack",
527 .syntax = "LOCAL_PEEK(<n>|<varname>)",
531 static int handle_gosub(struct ast_channel *chan, AGI *agi, int argc, char **argv)
533 int old_priority, priority;
534 char old_context[AST_MAX_CONTEXT], old_extension[AST_MAX_EXTENSION];
535 struct ast_app *theapp;
538 if (argc < 4 || argc > 5) {
539 return RESULT_SHOWUSAGE;
542 ast_debug(1, "Gosub called with %d arguments: 0:%s 1:%s 2:%s 3:%s 4:%s\n", argc, argv[0], argv[1], argv[2], argv[3], argc == 5 ? argv[4] : "");
544 if (sscanf(argv[3], "%d", &priority) != 1 || priority < 1) {
545 /* Lookup the priority label */
546 if ((priority = ast_findlabel_extension(chan, argv[1], argv[2], argv[3], chan->cid.cid_num)) < 0) {
547 ast_log(LOG_ERROR, "Priority '%s' not found in '%s@%s'\n", argv[3], argv[2], argv[1]);
548 ast_agi_send(agi->fd, chan, "200 result=-1 Gosub label not found\n");
549 return RESULT_FAILURE;
551 } else if (!ast_exists_extension(chan, argv[1], argv[2], priority, chan->cid.cid_num)) {
552 ast_agi_send(agi->fd, chan, "200 result=-1 Gosub label not found\n");
553 return RESULT_FAILURE;
556 /* Save previous location, since we're going to change it */
557 ast_copy_string(old_context, chan->context, sizeof(old_context));
558 ast_copy_string(old_extension, chan->exten, sizeof(old_extension));
559 old_priority = chan->priority;
561 if (!(theapp = pbx_findapp("Gosub"))) {
562 ast_log(LOG_ERROR, "Gosub() cannot be found in the list of loaded applications\n");
563 ast_agi_send(agi->fd, chan, "503 result=-2 Gosub is not loaded\n");
564 return RESULT_FAILURE;
567 /* Apparently, if you run ast_pbx_run on a channel that already has a pbx
568 * structure, you need to add 1 to the priority to get it to go to the
569 * right place. But if it doesn't have a pbx structure, then leaving off
570 * the 1 is the right thing to do. See how this code differs when we
571 * call a Gosub for the CALLEE channel in Dial or Queue.
574 if (asprintf(&gosub_args, "%s,%s,%d(%s)", argv[1], argv[2], priority + 1, argv[4]) < 0) {
575 ast_log(LOG_WARNING, "asprintf() failed: %s\n", strerror(errno));
579 if (asprintf(&gosub_args, "%s,%s,%d", argv[1], argv[2], priority + 1) < 0) {
580 ast_log(LOG_WARNING, "asprintf() failed: %s\n", strerror(errno));
588 ast_debug(1, "Trying gosub with arguments '%s'\n", gosub_args);
589 ast_copy_string(chan->context, "app_stack_gosub_virtual_context", sizeof(chan->context));
590 ast_copy_string(chan->exten, "s", sizeof(chan->exten));
593 if ((res = pbx_exec(chan, theapp, gosub_args)) == 0) {
594 struct ast_pbx *pbx = chan->pbx;
595 /* Suppress warning about PBX already existing */
597 ast_agi_send(agi->fd, chan, "100 result=0 Trying...\n");
599 ast_agi_send(agi->fd, chan, "200 result=0 Gosub complete\n");
605 ast_agi_send(agi->fd, chan, "200 result=%d Gosub failed\n", res);
607 ast_free(gosub_args);
609 ast_agi_send(agi->fd, chan, "503 result=-2 Memory allocation failure\n");
610 return RESULT_FAILURE;
613 /* Restore previous location */
614 ast_copy_string(chan->context, old_context, sizeof(chan->context));
615 ast_copy_string(chan->exten, old_extension, sizeof(chan->exten));
616 chan->priority = old_priority;
618 return RESULT_SUCCESS;
621 static char usage_gosub[] =
622 " Usage: GOSUB <context> <extension> <priority> [<optional-argument>]\n"
623 " Cause the channel to execute the specified dialplan subroutine, returning\n"
624 " to the dialplan with execution of a Return()\n";
626 struct agi_command gosub_agi_command =
627 { { "gosub", NULL }, handle_gosub, "Execute a dialplan subroutine", usage_gosub , 0 };
629 static int unload_module(void)
631 struct ast_context *con;
633 if (ast_agi_unregister(ast_module_info->self, &gosub_agi_command) == 1) {
634 if ((con = ast_context_find("app_stack_gosub_virtual_context"))) {
635 ast_context_remove_extension2(con, "s", 1, NULL, 0);
636 ast_context_destroy(con, "app_stack"); /* leave nothing behind */
640 ast_unregister_application(app_return);
641 ast_unregister_application(app_pop);
642 ast_unregister_application(app_gosubif);
643 ast_unregister_application(app_gosub);
644 ast_custom_function_unregister(&local_function);
645 ast_custom_function_unregister(&peek_function);
650 static int load_module(void)
652 struct ast_context *con;
654 if (ast_agi_register(ast_module_info->self, &gosub_agi_command) == 1) {
655 if (!(con = ast_context_find_or_create(NULL, NULL, "app_stack_gosub_virtual_context", "app_stack"))) {
656 ast_log(LOG_ERROR, "Virtual context 'app_stack_gosub_virtual_context' does not exist and unable to create\n");
657 return AST_MODULE_LOAD_DECLINE;
659 ast_add_extension2(con, 1, "s", 1, NULL, NULL, "KeepAlive", ast_strdup(""), ast_free_ptr, "app_stack");
663 ast_register_application_xml(app_pop, pop_exec);
664 ast_register_application_xml(app_return, return_exec);
665 ast_register_application_xml(app_gosubif, gosubif_exec);
666 ast_register_application_xml(app_gosub, gosub_exec);
667 ast_custom_function_register(&local_function);
668 ast_custom_function_register(&peek_function);
673 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Dialplan subroutines (Gosub, Return, etc)");