apps/app_stack.c

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (c) 2004-2006 Tilghman Lesher <app_stack_v003@the-tilghman.com>.
   5  *
   6  * This code is released by the author with no restrictions on usage.
   7  *
   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.
  13  *
  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.
  17  */
  18
  19 /*! \file
  20  *
  21  * \brief Stack applications Gosub, Return, etc.
  22  *
  23  * \author Tilghman Lesher <app_stack_v003@the-tilghman.com>
  24  *
  25  * \ingroup applications
  26  */
  27
  28 /*** MODULEINFO
  29         <use>res_agi</use>
  30  ***/
  31
  32 #include "asterisk.h"
  33
  34 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  35
  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"
  42
  43 /*** DOCUMENTATION
  44         <application name="Gosub" language="en_US">
  45                 <synopsis>
  46                         Jump to label, saving return address.
  47                 </synopsis>
  48                 <syntax>
  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" />
  54                         </parameter>
  55                 </syntax>
  56                 <description>
  57                         <para>Jumps to the label specified, saving the return address.</para>
  58                 </description>
  59                 <see-also>
  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>
  65                 </see-also>
  66         </application>
  67         <application name="GosubIf" language="en_US">
  68                 <synopsis>
  69                         Conditionally jump to label, saving return address.
  70                 </synopsis>
  71                 <syntax argsep="?">
  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" />
  77                                 </argument>
  78                                 <argument name="labeliffalse" hasparams="optional">
  79                                         <argument name="arg1" required="true" multiple="true" />
  80                                         <argument name="argN" />
  81                                 </argument>
  82                         </parameter>
  83                 </syntax>
  84                 <description>
  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>
  88                 </description>
  89                 <see-also>
  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>
  95                 </see-also>
  96         </application>
  97         <application name="Return" language="en_US">
  98                 <synopsis>
  99                         Return from gosub routine.
 100                 </synopsis>
 101                 <syntax>
 102                         <parameter name="value">
 103                                 <para>Return value.</para>
 104                         </parameter>
 105                 </syntax>
 106                 <description>
 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>
 109                 </description>
 110                 <see-also>
 111                         <ref type="application">Gosub</ref>
 112                         <ref type="application">StackPop</ref>
 113                 </see-also>
 114         </application>
 115         <application name="StackPop" language="en_US">
 116                 <synopsis>
 117                         Remove one address from gosub stack.
 118                 </synopsis>
 119                 <syntax />
 120                 <description>
 121                         <para>Removes last label on the stack, discarding it.</para>
 122                 </description>
 123                 <see-also>
 124                         <ref type="application">Return</ref>
 125                         <ref type="application">Gosub</ref>
 126                 </see-also>
 127         </application>
 128         <function name="LOCAL" language="en_US">
 129                 <synopsis>
 130                         Manage variables local to the gosub stack frame.
 131                 </synopsis>
 132                 <syntax>
 133                         <parameter name="varname" required="true" />
 134                 </syntax>
 135                 <description>
 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>
 138                 </description>
 139                 <see-also>
 140                         <ref type="application">Gosub</ref>
 141                         <ref type="application">GosubIf</ref>
 142                         <ref type="application">Return</ref>
 143                 </see-also>
 144         </function>
 145         <function name="LOCAL_PEEK" language="en_US">
 146                 <synopsis>
 147                         Retrieve variables hidden by the local gosub stack frame.
 148                 </synopsis>
 149                 <syntax>
 150                         <parameter name="n" required="true" />
 151                         <parameter name="varname" required="true" />
 152                 </syntax>
 153                 <description>
 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 <variable>foo</variable>, since the value of <replaceable>n</replaceable>
 157                         peeks under 0 levels of stack frames; in other words, 0 is the current level.  If
 158                         <replaceable>n</replaceable> exceeds the available number of stack frames, then an empty
 159                         string is returned.</para>
 160                 </description>
 161                 <see-also>
 162                         <ref type="application">Gosub</ref>
 163                         <ref type="application">GosubIf</ref>
 164                         <ref type="application">Return</ref>
 165                 </see-also>
 166         </function>
 167         <agi name="gosub" language="en_US">
 168                 <synopsis>
 169                         Cause the channel to execute the specified dialplan subroutine.
 170                 </synopsis>
 171                 <syntax>
 172                         <parameter name="context" required="true" />
 173                         <parameter name="extension" required="true" />
 174                         <parameter name="priority" required="true" />
 175                         <parameter name="optional-argument" />
 176                 </syntax>
 177                 <description>
 178                         <para>Cause the channel to execute the specified dialplan subroutine,
 179                         returning to the dialplan with execution of a Return().</para>
 180                 </description>
 181         </agi>
 182  ***/
 183
 184 static const char * const app_gosub = "Gosub";
 185 static const char * const app_gosubif = "GosubIf";
 186 static const char * const app_return = "Return";
 187 static const char * const app_pop = "StackPop";
 188
 189 static void gosub_free(void *data);
 190
 191 static struct ast_datastore_info stack_info = {
 192         .type = "GOSUB",
 193         .destroy = gosub_free,
 194 };
 195
 196 struct gosub_stack_frame {
 197         AST_LIST_ENTRY(gosub_stack_frame) entries;
 198         /* 100 arguments is all that we support anyway, but this will handle up to 255 */
 199         unsigned char arguments;
 200         struct varshead varshead;
 201         int priority;
 202         unsigned int is_agi:1;
 203         char *context;
 204         char extension[0];
 205 };
 206
 207 static int frame_set_var(struct ast_channel *chan, struct gosub_stack_frame *frame, const char *var, const char *value)
 208 {
 209         struct ast_var_t *variables;
 210         int found = 0;
 211
 212         /* Does this variable already exist? */
 213         AST_LIST_TRAVERSE(&frame->varshead, variables, entries) {
 214                 if (!strcmp(var, ast_var_name(variables))) {
 215                         found = 1;
 216                         break;
 217                 }
 218         }
 219
 220         if (!found) {
 221                 variables = ast_var_assign(var, "");
 222                 AST_LIST_INSERT_HEAD(&frame->varshead, variables, entries);
 223                 pbx_builtin_pushvar_helper(chan, var, value);
 224         } else {
 225                 pbx_builtin_setvar_helper(chan, var, value);
 226         }
 227
 228         manager_event(EVENT_FLAG_DIALPLAN, "VarSet",
 229                 "Channel: %s\r\n"
 230                 "Variable: LOCAL(%s)\r\n"
 231                 "Value: %s\r\n"
 232                 "Uniqueid: %s\r\n",
 233                 chan->name, var, value, chan->uniqueid);
 234         return 0;
 235 }
 236
 237 static void gosub_release_frame(struct ast_channel *chan, struct gosub_stack_frame *frame)
 238 {
 239         struct ast_var_t *vardata;
 240
 241         /* If chan is not defined, then we're calling it as part of gosub_free,
 242          * and the channel variables will be deallocated anyway.  Otherwise, we're
 243          * just releasing a single frame, so we need to clean up the arguments for
 244          * that frame, so that we re-expose the variables from the previous frame
 245          * that were hidden by this one.
 246          */
 247         while ((vardata = AST_LIST_REMOVE_HEAD(&frame->varshead, entries))) {
 248                 if (chan)
 249                         pbx_builtin_setvar_helper(chan, ast_var_name(vardata), NULL);
 250                 ast_var_delete(vardata);
 251         }
 252
 253         ast_free(frame);
 254 }
 255
 256 static struct gosub_stack_frame *gosub_allocate_frame(const char *context, const char *extension, int priority, unsigned char arguments)
 257 {
 258         struct gosub_stack_frame *new = NULL;
 259         int len_extension = strlen(extension), len_context = strlen(context);
 260
 261         if ((new = ast_calloc(1, sizeof(*new) + 2 + len_extension + len_context))) {
 262                 AST_LIST_HEAD_INIT_NOLOCK(&new->varshead);
 263                 strcpy(new->extension, extension);
 264                 new->context = new->extension + len_extension + 1;
 265                 strcpy(new->context, context);
 266                 new->priority = priority;
 267                 new->arguments = arguments;
 268         }
 269         return new;
 270 }
 271
 272 static void gosub_free(void *data)
 273 {
 274         AST_LIST_HEAD(, gosub_stack_frame) *oldlist = data;
 275         struct gosub_stack_frame *oldframe;
 276         AST_LIST_LOCK(oldlist);
 277         while ((oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries))) {
 278                 gosub_release_frame(NULL, oldframe);
 279         }
 280         AST_LIST_UNLOCK(oldlist);
 281         AST_LIST_HEAD_DESTROY(oldlist);
 282         ast_free(oldlist);
 283 }
 284
 285 static int pop_exec(struct ast_channel *chan, const char *data)
 286 {
 287         struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
 288         struct gosub_stack_frame *oldframe;
 289         AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 290
 291         if (!stack_store) {
 292                 ast_log(LOG_WARNING, "%s called with no gosub stack allocated.\n", app_pop);
 293                 return 0;
 294         }
 295
 296         oldlist = stack_store->data;
 297         AST_LIST_LOCK(oldlist);
 298         oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries);
 299         AST_LIST_UNLOCK(oldlist);
 300
 301         if (oldframe) {
 302                 gosub_release_frame(chan, oldframe);
 303         } else {
 304                 ast_debug(1, "%s called with an empty gosub stack\n", app_pop);
 305         }
 306         return 0;
 307 }
 308
 309 static int return_exec(struct ast_channel *chan, const char *data)
 310 {
 311         struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
 312         struct gosub_stack_frame *oldframe;
 313         AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 314         const char *retval = data;
 315         int res = 0;
 316
 317         if (!stack_store) {
 318                 ast_log(LOG_ERROR, "Return without Gosub: stack is unallocated\n");
 319                 return -1;
 320         }
 321
 322         oldlist = stack_store->data;
 323         AST_LIST_LOCK(oldlist);
 324         oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries);
 325         AST_LIST_UNLOCK(oldlist);
 326
 327         if (!oldframe) {
 328                 ast_log(LOG_ERROR, "Return without Gosub: stack is empty\n");
 329                 return -1;
 330         } else if (oldframe->is_agi) {
 331                 /* Exit from AGI */
 332                 res = -1;
 333         }
 334
 335         ast_explicit_goto(chan, oldframe->context, oldframe->extension, oldframe->priority);
 336         gosub_release_frame(chan, oldframe);
 337
 338         /* Set a return value, if any */
 339         pbx_builtin_setvar_helper(chan, "GOSUB_RETVAL", S_OR(retval, ""));
 340         return res;
 341 }
 342
 343 static int gosub_exec(struct ast_channel *chan, const char *data)
 344 {
 345         struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
 346         AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 347         struct gosub_stack_frame *newframe;
 348         char argname[15], *tmp = ast_strdupa(data), *label, *endparen;
 349         int i;
 350         AST_DECLARE_APP_ARGS(args2,
 351                 AST_APP_ARG(argval)[100];
 352         );
 353
 354         if (ast_strlen_zero(data)) {
 355                 ast_log(LOG_ERROR, "%s requires an argument: %s([[context,]exten,]priority[(arg1[,...][,argN])])\n", app_gosub, app_gosub);
 356                 return -1;
 357         }
 358
 359         if (!stack_store) {
 360                 ast_debug(1, "Channel %s has no datastore, so we're allocating one.\n", chan->name);
 361                 stack_store = ast_datastore_alloc(&stack_info, NULL);
 362                 if (!stack_store) {
 363                         ast_log(LOG_ERROR, "Unable to allocate new datastore.  Gosub will fail.\n");
 364                         return -1;
 365                 }
 366
 367                 oldlist = ast_calloc(1, sizeof(*oldlist));
 368                 if (!oldlist) {
 369                         ast_log(LOG_ERROR, "Unable to allocate datastore list head.  Gosub will fail.\n");
 370                         ast_datastore_free(stack_store);
 371                         return -1;
 372                 }
 373
 374                 stack_store->data = oldlist;
 375                 AST_LIST_HEAD_INIT(oldlist);
 376                 ast_channel_datastore_add(chan, stack_store);
 377         }
 378
 379         /* Separate the arguments from the label */
 380         /* NOTE:  you cannot use ast_app_separate_args for this, because '(' cannot be used as a delimiter. */
 381         label = strsep(&tmp, "(");
 382         if (tmp) {
 383                 endparen = strrchr(tmp, ')');
 384                 if (endparen)
 385                         *endparen = '\0';
 386                 else
 387                         ast_log(LOG_WARNING, "Ouch.  No closing paren: '%s'?\n", (char *)data);
 388                 AST_STANDARD_RAW_ARGS(args2, tmp);
 389         } else
 390                 args2.argc = 0;
 391
 392         /* Create the return address, but don't save it until we know that the Gosub destination exists */
 393         newframe = gosub_allocate_frame(chan->context, chan->exten, chan->priority + 1, args2.argc);
 394
 395         if (!newframe) {
 396                 return -1;
 397         }
 398
 399         if (ast_parseable_goto(chan, label)) {
 400                 ast_log(LOG_ERROR, "Gosub address is invalid: '%s'\n", (char *)data);
 401                 ast_free(newframe);
 402                 return -1;
 403         }
 404
 405         if (!ast_exists_extension(chan, chan->context, chan->exten, ast_test_flag(chan, AST_FLAG_IN_AUTOLOOP) ? chan->priority + 1 : chan->priority, chan->cid.cid_num)) {
 406                 ast_log(LOG_ERROR, "Attempt to reach a non-existent destination for gosub: (Context:%s, Extension:%s, Priority:%d)\n",
 407                                 chan->context, chan->exten, chan->priority);
 408                 ast_copy_string(chan->context, newframe->context, sizeof(chan->context));
 409                 ast_copy_string(chan->exten, newframe->extension, sizeof(chan->exten));
 410                 chan->priority = newframe->priority;
 411                 ast_free(newframe);
 412                 return -1;
 413         }
 414
 415         /* Now that we know for certain that we're going to a new location, set our arguments */
 416         for (i = 0; i < args2.argc; i++) {
 417                 snprintf(argname, sizeof(argname), "ARG%d", i + 1);
 418                 frame_set_var(chan, newframe, argname, args2.argval[i]);
 419                 ast_debug(1, "Setting '%s' to '%s'\n", argname, args2.argval[i]);
 420         }
 421         snprintf(argname, sizeof(argname), "%d", args2.argc);
 422         frame_set_var(chan, newframe, "ARGC", argname);
 423
 424         /* And finally, save our return address */
 425         oldlist = stack_store->data;
 426         AST_LIST_LOCK(oldlist);
 427         AST_LIST_INSERT_HEAD(oldlist, newframe, entries);
 428         AST_LIST_UNLOCK(oldlist);
 429
 430         return 0;
 431 }
 432
 433 static int gosubif_exec(struct ast_channel *chan, const char *data)
 434 {
 435         char *args;
 436         int res=0;
 437         AST_DECLARE_APP_ARGS(cond,
 438                 AST_APP_ARG(ition);
 439                 AST_APP_ARG(labels);
 440         );
 441         AST_DECLARE_APP_ARGS(label,
 442                 AST_APP_ARG(iftrue);
 443                 AST_APP_ARG(iffalse);
 444         );
 445
 446         if (ast_strlen_zero(data)) {
 447                 ast_log(LOG_WARNING, "GosubIf requires an argument: GosubIf(cond?label1(args):label2(args)\n");
 448                 return 0;
 449         }
 450
 451         args = ast_strdupa(data);
 452         AST_NONSTANDARD_RAW_ARGS(cond, args, '?');
 453         if (cond.argc != 2) {
 454                 ast_log(LOG_WARNING, "GosubIf requires an argument: GosubIf(cond?label1(args):label2(args)\n");
 455                 return 0;
 456         }
 457
 458         AST_NONSTANDARD_RAW_ARGS(label, cond.labels, ':');
 459
 460         if (pbx_checkcondition(cond.ition)) {
 461                 if (!ast_strlen_zero(label.iftrue))
 462                         res = gosub_exec(chan, label.iftrue);
 463         } else if (!ast_strlen_zero(label.iffalse)) {
 464                 res = gosub_exec(chan, label.iffalse);
 465         }
 466
 467         return res;
 468 }
 469
 470 static int local_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
 471 {
 472         struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
 473         AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 474         struct gosub_stack_frame *frame;
 475         struct ast_var_t *variables;
 476
 477         if (!stack_store)
 478                 return -1;
 479
 480         oldlist = stack_store->data;
 481         AST_LIST_LOCK(oldlist);
 482         if (!(frame = AST_LIST_FIRST(oldlist))) {
 483                 /* Not within a Gosub routine */
 484                 AST_LIST_UNLOCK(oldlist);
 485                 return -1;
 486         }
 487
 488         AST_LIST_TRAVERSE(&frame->varshead, variables, entries) {
 489                 if (!strcmp(data, ast_var_name(variables))) {
 490                         const char *tmp;
 491                         ast_channel_lock(chan);
 492                         tmp = pbx_builtin_getvar_helper(chan, data);
 493                         ast_copy_string(buf, S_OR(tmp, ""), len);
 494                         ast_channel_unlock(chan);
 495                         break;
 496                 }
 497         }
 498         AST_LIST_UNLOCK(oldlist);
 499         return 0;
 500 }
 501
 502 static int local_write(struct ast_channel *chan, const char *cmd, char *var, const char *value)
 503 {
 504         struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
 505         AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 506         struct gosub_stack_frame *frame;
 507
 508         if (!stack_store) {
 509                 ast_log(LOG_ERROR, "Tried to set LOCAL(%s), but we aren't within a Gosub routine\n", var);
 510                 return -1;
 511         }
 512
 513         oldlist = stack_store->data;
 514         AST_LIST_LOCK(oldlist);
 515         frame = AST_LIST_FIRST(oldlist);
 516
 517         if (frame)
 518                 frame_set_var(chan, frame, var, value);
 519
 520         AST_LIST_UNLOCK(oldlist);
 521
 522         return 0;
 523 }
 524
 525 static struct ast_custom_function local_function = {
 526         .name = "LOCAL",
 527         .write = local_write,
 528         .read = local_read,
 529 };
 530
 531 static int peek_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
 532 {
 533         int found = 0, n;
 534         struct ast_var_t *variables;
 535         AST_DECLARE_APP_ARGS(args,
 536                 AST_APP_ARG(n);
 537                 AST_APP_ARG(name);
 538         );
 539
 540         if (!chan) {
 541                 ast_log(LOG_ERROR, "LOCAL_PEEK must be called on an active channel\n");
 542                 return -1;
 543         }
 544
 545         AST_STANDARD_RAW_ARGS(args, data);
 546         n = atoi(args.n);
 547         *buf = '\0';
 548
 549         ast_channel_lock(chan);
 550         AST_LIST_TRAVERSE(&chan->varshead, variables, entries) {
 551                 if (!strcmp(args.name, ast_var_name(variables)) && ++found > n) {
 552                         ast_copy_string(buf, ast_var_value(variables), len);
 553                         break;
 554                 }
 555         }
 556         ast_channel_unlock(chan);
 557         return 0;
 558 }
 559
 560 static struct ast_custom_function peek_function = {
 561         .name = "LOCAL_PEEK",
 562         .read = peek_read,
 563 };
 564
 565 static int handle_gosub(struct ast_channel *chan, AGI *agi, int argc, const char * const *argv)
 566 {
 567         int old_priority, priority;
 568         char old_context[AST_MAX_CONTEXT], old_extension[AST_MAX_EXTENSION];
 569         struct ast_app *theapp;
 570         char *gosub_args;
 571
 572         if (argc < 4 || argc > 5) {
 573                 return RESULT_SHOWUSAGE;
 574         }
 575
 576         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] : "");
 577
 578         if (sscanf(argv[3], "%30d", &priority) != 1 || priority < 1) {
 579                 /* Lookup the priority label */
 580                 if ((priority = ast_findlabel_extension(chan, argv[1], argv[2], argv[3], chan->cid.cid_num)) < 0) {
 581                         ast_log(LOG_ERROR, "Priority '%s' not found in '%s@%s'\n", argv[3], argv[2], argv[1]);
 582                         ast_agi_send(agi->fd, chan, "200 result=-1 Gosub label not found\n");
 583                         return RESULT_FAILURE;
 584                 }
 585         } else if (!ast_exists_extension(chan, argv[1], argv[2], priority, chan->cid.cid_num)) {
 586                 ast_agi_send(agi->fd, chan, "200 result=-1 Gosub label not found\n");
 587                 return RESULT_FAILURE;
 588         }
 589
 590         /* Save previous location, since we're going to change it */
 591         ast_copy_string(old_context, chan->context, sizeof(old_context));
 592         ast_copy_string(old_extension, chan->exten, sizeof(old_extension));
 593         old_priority = chan->priority;
 594
 595         if (!(theapp = pbx_findapp("Gosub"))) {
 596                 ast_log(LOG_ERROR, "Gosub() cannot be found in the list of loaded applications\n");
 597                 ast_agi_send(agi->fd, chan, "503 result=-2 Gosub is not loaded\n");
 598                 return RESULT_FAILURE;
 599         }
 600
 601         /* Apparently, if you run ast_pbx_run on a channel that already has a pbx
 602          * structure, you need to add 1 to the priority to get it to go to the
 603          * right place.  But if it doesn't have a pbx structure, then leaving off
 604          * the 1 is the right thing to do.  See how this code differs when we
 605          * call a Gosub for the CALLEE channel in Dial or Queue.
 606          */
 607         if (argc == 5) {
 608                 if (asprintf(&gosub_args, "%s,%s,%d(%s)", argv[1], argv[2], priority + 1, argv[4]) < 0) {
 609                         ast_log(LOG_WARNING, "asprintf() failed: %s\n", strerror(errno));
 610                         gosub_args = NULL;
 611                 }
 612         } else {
 613                 if (asprintf(&gosub_args, "%s,%s,%d", argv[1], argv[2], priority + 1) < 0) {
 614                         ast_log(LOG_WARNING, "asprintf() failed: %s\n", strerror(errno));
 615                         gosub_args = NULL;
 616                 }
 617         }
 618
 619         if (gosub_args) {
 620                 int res;
 621
 622                 ast_debug(1, "Trying gosub with arguments '%s'\n", gosub_args);
 623
 624                 if ((res = pbx_exec(chan, theapp, gosub_args)) == 0) {
 625                         struct ast_pbx *pbx = chan->pbx;
 626                         struct ast_pbx_args args;
 627                         struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
 628                         AST_LIST_HEAD(, gosub_stack_frame) *oldlist = stack_store->data;
 629                         struct gosub_stack_frame *cur = AST_LIST_FIRST(oldlist);
 630                         cur->is_agi = 1;
 631
 632                         memset(&args, 0, sizeof(args));
 633                         args.no_hangup_chan = 1;
 634                         /* Suppress warning about PBX already existing */
 635                         chan->pbx = NULL;
 636                         ast_agi_send(agi->fd, chan, "100 result=0 Trying...\n");
 637                         ast_pbx_run_args(chan, &args);
 638                         ast_agi_send(agi->fd, chan, "200 result=0 Gosub complete\n");
 639                         if (chan->pbx) {
 640                                 ast_free(chan->pbx);
 641                         }
 642                         chan->pbx = pbx;
 643                 } else {
 644                         ast_agi_send(agi->fd, chan, "200 result=%d Gosub failed\n", res);
 645                 }
 646                 ast_free(gosub_args);
 647         } else {
 648                 ast_agi_send(agi->fd, chan, "503 result=-2 Memory allocation failure\n");
 649                 return RESULT_FAILURE;
 650         }
 651
 652         /* Restore previous location */
 653         ast_copy_string(chan->context, old_context, sizeof(chan->context));
 654         ast_copy_string(chan->exten, old_extension, sizeof(chan->exten));
 655         chan->priority = old_priority;
 656
 657         return RESULT_SUCCESS;
 658 }
 659
 660 static struct agi_command gosub_agi_command =
 661         { { "gosub", NULL }, handle_gosub, NULL, NULL, 0 };
 662
 663 static int unload_module(void)
 664 {
 665         ast_agi_unregister(ast_module_info->self, &gosub_agi_command);
 666
 667         ast_unregister_application(app_return);
 668         ast_unregister_application(app_pop);
 669         ast_unregister_application(app_gosubif);
 670         ast_unregister_application(app_gosub);
 671         ast_custom_function_unregister(&local_function);
 672         ast_custom_function_unregister(&peek_function);
 673
 674         return 0;
 675 }
 676
 677 static int load_module(void)
 678 {
 679         ast_agi_register(ast_module_info->self, &gosub_agi_command);
 680
 681         ast_register_application_xml(app_pop, pop_exec);
 682         ast_register_application_xml(app_return, return_exec);
 683         ast_register_application_xml(app_gosubif, gosubif_exec);
 684         ast_register_application_xml(app_gosub, gosub_exec);
 685         ast_custom_function_register(&local_function);
 686         ast_custom_function_register(&peek_function);
 687
 688         return 0;
 689 }
 690
 691 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Dialplan subroutines (Gosub, Return, etc)");