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 #include "asterisk.h"
  29
  30 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  31
  32 #include "asterisk/pbx.h"
  33 #include "asterisk/module.h"
  34 #include "asterisk/app.h"
  35 #include "asterisk/manager.h"
  36 #include "asterisk/channel.h"
  37 #include "asterisk/agi.h"
  38
  39 static int agi_loaded = 0;
  40
  41 static const char *app_gosub = "Gosub";
  42 static const char *app_gosubif = "GosubIf";
  43 static const char *app_return = "Return";
  44 static const char *app_pop = "StackPop";
  45
  46 static const char *gosub_synopsis = "Jump to label, saving return address";
  47 static const char *gosubif_synopsis = "Conditionally jump to label, saving return address";
  48 static const char *return_synopsis = "Return from gosub routine";
  49 static const char *pop_synopsis = "Remove one address from gosub stack";
  50
  51 static const char *gosub_descrip =
  52 "  Gosub([[context,]exten,]priority[(arg1[,...][,argN])]):\n"
  53 "Jumps to the label specified, saving the return address.\n";
  54 static const char *gosubif_descrip =
  55 "  GosubIf(condition?labeliftrue[(arg1[,...])][:labeliffalse[(arg1[,...])]]):\n"
  56 "If the condition is true, then jump to labeliftrue.  If false, jumps to\n"
  57 "labeliffalse, if specified.  In either case, a jump saves the return point\n"
  58 "in the dialplan, to be returned to with a Return.\n";
  59 static const char *return_descrip =
  60 "  Return([return-value]):\n"
  61 "Jumps to the last label on the stack, removing it.  The return value, if\n"
  62 "any, is saved in the channel variable GOSUB_RETVAL.\n";
  63 static const char *pop_descrip =
  64 "  StackPop():\n"
  65 "Removes last label on the stack, discarding it.\n";
  66
  67 static void gosub_free(void *data);
  68
  69 static struct ast_datastore_info stack_info = {
  70         .type = "GOSUB",
  71         .destroy = gosub_free,
  72 };
  73
  74 struct gosub_stack_frame {
  75         AST_LIST_ENTRY(gosub_stack_frame) entries;
  76         /* 100 arguments is all that we support anyway, but this will handle up to 255 */
  77         unsigned char arguments;
  78         struct varshead varshead;
  79         int priority;
  80         char *context;
  81         char extension[0];
  82 };
  83
  84 static int frame_set_var(struct ast_channel *chan, struct gosub_stack_frame *frame, const char *var, const char *value)
  85 {
  86         struct ast_var_t *variables;
  87         int found = 0;
  88
  89         /* Does this variable already exist? */
  90         AST_LIST_TRAVERSE(&frame->varshead, variables, entries) {
  91                 if (!strcmp(var, ast_var_name(variables))) {
  92                         found = 1;
  93                         break;
  94                 }
  95         }
  96
  97         if (!ast_strlen_zero(value)) {
  98                 if (!found) {
  99                         variables = ast_var_assign(var, "");
 100                         AST_LIST_INSERT_HEAD(&frame->varshead, variables, entries);
 101                         pbx_builtin_pushvar_helper(chan, var, value);
 102                 } else
 103                         pbx_builtin_setvar_helper(chan, var, value);
 104
 105                 manager_event(EVENT_FLAG_DIALPLAN, "VarSet",
 106                         "Channel: %s\r\n"
 107                         "Variable: LOCAL(%s)\r\n"
 108                         "Value: %s\r\n"
 109                         "Uniqueid: %s\r\n",
 110                         chan->name, var, value, chan->uniqueid);
 111         }
 112         return 0;
 113 }
 114
 115 static void gosub_release_frame(struct ast_channel *chan, struct gosub_stack_frame *frame)
 116 {
 117         unsigned char i;
 118         char argname[15];
 119         struct ast_var_t *vardata;
 120
 121         /* If chan is not defined, then we're calling it as part of gosub_free,
 122          * and the channel variables will be deallocated anyway.  Otherwise, we're
 123          * just releasing a single frame, so we need to clean up the arguments for
 124          * that frame, so that we re-expose the variables from the previous frame
 125          * that were hidden by this one.
 126          */
 127         if (chan) {
 128                 for (i = 1; i <= frame->arguments && i != 0; i++) {
 129                         snprintf(argname, sizeof(argname), "ARG%hhd", i);
 130                         pbx_builtin_setvar_helper(chan, argname, NULL);
 131                 }
 132         }
 133
 134         /* Delete local variables */
 135         while ((vardata = AST_LIST_REMOVE_HEAD(&frame->varshead, entries))) {
 136                 if (chan)
 137                         pbx_builtin_setvar_helper(chan, ast_var_name(vardata), NULL);
 138                 ast_var_delete(vardata);
 139         }
 140
 141         ast_free(frame);
 142 }
 143
 144 static struct gosub_stack_frame *gosub_allocate_frame(const char *context, const char *extension, int priority, unsigned char arguments)
 145 {
 146         struct gosub_stack_frame *new = NULL;
 147         int len_extension = strlen(extension), len_context = strlen(context);
 148
 149         if ((new = ast_calloc(1, sizeof(*new) + 2 + len_extension + len_context))) {
 150                 AST_LIST_HEAD_INIT_NOLOCK(&new->varshead);
 151                 strcpy(new->extension, extension);
 152                 new->context = new->extension + len_extension + 1;
 153                 strcpy(new->context, context);
 154                 new->priority = priority;
 155                 new->arguments = arguments;
 156         }
 157         return new;
 158 }
 159
 160 static void gosub_free(void *data)
 161 {
 162         AST_LIST_HEAD(, gosub_stack_frame) *oldlist = data;
 163         struct gosub_stack_frame *oldframe;
 164         AST_LIST_LOCK(oldlist);
 165         while ((oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries))) {
 166                 gosub_release_frame(NULL, oldframe);
 167         }
 168         AST_LIST_UNLOCK(oldlist);
 169         AST_LIST_HEAD_DESTROY(oldlist);
 170         ast_free(oldlist);
 171 }
 172
 173 static int pop_exec(struct ast_channel *chan, void *data)
 174 {
 175         struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
 176         struct gosub_stack_frame *oldframe;
 177         AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 178
 179         if (!stack_store) {
 180                 ast_log(LOG_WARNING, "%s called with no gosub stack allocated.\n", app_pop);
 181                 return 0;
 182         }
 183
 184         oldlist = stack_store->data;
 185         AST_LIST_LOCK(oldlist);
 186         oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries);
 187         AST_LIST_UNLOCK(oldlist);
 188
 189         if (oldframe) {
 190                 gosub_release_frame(chan, oldframe);
 191         } else {
 192                 ast_debug(1, "%s called with an empty gosub stack\n", app_pop);
 193         }
 194         return 0;
 195 }
 196
 197 static int return_exec(struct ast_channel *chan, void *data)
 198 {
 199         struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
 200         struct gosub_stack_frame *oldframe;
 201         AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 202         char *retval = data;
 203
 204         if (!stack_store) {
 205                 ast_log(LOG_ERROR, "Return without Gosub: stack is unallocated\n");
 206                 return -1;
 207         }
 208
 209         oldlist = stack_store->data;
 210         AST_LIST_LOCK(oldlist);
 211         oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries);
 212         AST_LIST_UNLOCK(oldlist);
 213
 214         if (!oldframe) {
 215                 ast_log(LOG_ERROR, "Return without Gosub: stack is empty\n");
 216                 return -1;
 217         }
 218
 219         ast_explicit_goto(chan, oldframe->context, oldframe->extension, oldframe->priority);
 220         gosub_release_frame(chan, oldframe);
 221
 222         /* Set a return value, if any */
 223         pbx_builtin_setvar_helper(chan, "GOSUB_RETVAL", S_OR(retval, ""));
 224         return 0;
 225 }
 226
 227 static int gosub_exec(struct ast_channel *chan, void *data)
 228 {
 229         struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
 230         AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 231         struct gosub_stack_frame *newframe;
 232         char argname[15], *tmp = ast_strdupa(data), *label, *endparen;
 233         int i;
 234         AST_DECLARE_APP_ARGS(args2,
 235                 AST_APP_ARG(argval)[100];
 236         );
 237
 238         if (ast_strlen_zero(data)) {
 239                 ast_log(LOG_ERROR, "%s requires an argument: %s([[context,]exten,]priority[(arg1[,...][,argN])])\n", app_gosub, app_gosub);
 240                 return -1;
 241         }
 242
 243         if (!stack_store) {
 244                 ast_debug(1, "Channel %s has no datastore, so we're allocating one.\n", chan->name);
 245                 stack_store = ast_channel_datastore_alloc(&stack_info, NULL);
 246                 if (!stack_store) {
 247                         ast_log(LOG_ERROR, "Unable to allocate new datastore.  Gosub will fail.\n");
 248                         return -1;
 249                 }
 250
 251                 oldlist = ast_calloc(1, sizeof(*oldlist));
 252                 if (!oldlist) {
 253                         ast_log(LOG_ERROR, "Unable to allocate datastore list head.  Gosub will fail.\n");
 254                         ast_channel_datastore_free(stack_store);
 255                         return -1;
 256                 }
 257
 258                 stack_store->data = oldlist;
 259                 AST_LIST_HEAD_INIT(oldlist);
 260                 ast_channel_datastore_add(chan, stack_store);
 261         }
 262
 263         /* Separate the arguments from the label */
 264         /* NOTE:  you cannot use ast_app_separate_args for this, because '(' cannot be used as a delimiter. */
 265         label = strsep(&tmp, "(");
 266         if (tmp) {
 267                 endparen = strrchr(tmp, ')');
 268                 if (endparen)
 269                         *endparen = '\0';
 270                 else
 271                         ast_log(LOG_WARNING, "Ouch.  No closing paren: '%s'?\n", (char *)data);
 272                 AST_STANDARD_APP_ARGS(args2, tmp);
 273         } else
 274                 args2.argc = 0;
 275
 276         /* Create the return address, but don't save it until we know that the Gosub destination exists */
 277         newframe = gosub_allocate_frame(chan->context, chan->exten, chan->priority + 1, args2.argc);
 278
 279         if (!newframe)
 280                 return -1;
 281
 282         if (ast_parseable_goto(chan, label)) {
 283                 ast_log(LOG_ERROR, "Gosub address is invalid: '%s'\n", (char *)data);
 284                 ast_free(newframe);
 285                 return -1;
 286         }
 287
 288         /* Now that we know for certain that we're going to a new location, set our arguments */
 289         for (i = 0; i < args2.argc; i++) {
 290                 snprintf(argname, sizeof(argname), "ARG%d", i + 1);
 291                 frame_set_var(chan, newframe, argname, args2.argval[i]);
 292                 ast_debug(1, "Setting '%s' to '%s'\n", argname, args2.argval[i]);
 293         }
 294
 295         /* And finally, save our return address */
 296         oldlist = stack_store->data;
 297         AST_LIST_LOCK(oldlist);
 298         AST_LIST_INSERT_HEAD(oldlist, newframe, entries);
 299         AST_LIST_UNLOCK(oldlist);
 300
 301         return 0;
 302 }
 303
 304 static int gosubif_exec(struct ast_channel *chan, void *data)
 305 {
 306         char *args;
 307         int res=0;
 308         AST_DECLARE_APP_ARGS(cond,
 309                 AST_APP_ARG(ition);
 310                 AST_APP_ARG(labels);
 311         );
 312         AST_DECLARE_APP_ARGS(label,
 313                 AST_APP_ARG(iftrue);
 314                 AST_APP_ARG(iffalse);
 315         );
 316
 317         if (ast_strlen_zero(data)) {
 318                 ast_log(LOG_WARNING, "GosubIf requires an argument: GosubIf(cond?label1(args):label2(args)\n");
 319                 return 0;
 320         }
 321
 322         args = ast_strdupa(data);
 323         AST_NONSTANDARD_APP_ARGS(cond, args, '?');
 324         if (cond.argc != 2) {
 325                 ast_log(LOG_WARNING, "GosubIf requires an argument: GosubIf(cond?label1(args):label2(args)\n");
 326                 return 0;
 327         }
 328
 329         AST_NONSTANDARD_APP_ARGS(label, cond.labels, ':');
 330
 331         if (pbx_checkcondition(cond.ition)) {
 332                 if (!ast_strlen_zero(label.iftrue))
 333                         res = gosub_exec(chan, label.iftrue);
 334         } else if (!ast_strlen_zero(label.iffalse)) {
 335                 res = gosub_exec(chan, label.iffalse);
 336         }
 337
 338         return res;
 339 }
 340
 341 static int local_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
 342 {
 343         struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
 344         AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 345         struct gosub_stack_frame *frame;
 346         struct ast_var_t *variables;
 347
 348         if (!stack_store)
 349                 return -1;
 350
 351         oldlist = stack_store->data;
 352         AST_LIST_LOCK(oldlist);
 353         frame = AST_LIST_FIRST(oldlist);
 354         AST_LIST_TRAVERSE(&frame->varshead, variables, entries) {
 355                 if (!strcmp(data, ast_var_name(variables))) {
 356                         const char *tmp;
 357                         ast_channel_lock(chan);
 358                         tmp = pbx_builtin_getvar_helper(chan, data);
 359                         ast_copy_string(buf, S_OR(tmp, ""), len);
 360                         ast_channel_unlock(chan);
 361                         break;
 362                 }
 363         }
 364         AST_LIST_UNLOCK(oldlist);
 365         return 0;
 366 }
 367
 368 static int local_write(struct ast_channel *chan, const char *cmd, char *var, const char *value)
 369 {
 370         struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
 371         AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 372         struct gosub_stack_frame *frame;
 373
 374         if (!stack_store) {
 375                 ast_log(LOG_ERROR, "Tried to set LOCAL(%s), but we aren't within a Gosub routine\n", var);
 376                 return -1;
 377         }
 378
 379         oldlist = stack_store->data;
 380         AST_LIST_LOCK(oldlist);
 381         frame = AST_LIST_FIRST(oldlist);
 382
 383         if (frame)
 384                 frame_set_var(chan, frame, var, value);
 385
 386         AST_LIST_UNLOCK(oldlist);
 387
 388         return 0;
 389 }
 390
 391 static struct ast_custom_function local_function = {
 392         .name = "LOCAL",
 393         .synopsis = "Variables local to the gosub stack frame",
 394         .syntax = "LOCAL(<varname>)",
 395         .write = local_write,
 396         .read = local_read,
 397 };
 398
 399 static int handle_gosub(struct ast_channel *chan, AGI *agi, int argc, char **argv)
 400 {
 401         int old_priority, priority;
 402         char old_context[AST_MAX_CONTEXT], old_extension[AST_MAX_EXTENSION];
 403         struct ast_app *theapp;
 404         char *gosub_args;
 405
 406         if (argc < 4 || argc > 5) {
 407                 return RESULT_SHOWUSAGE;
 408         }
 409
 410         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] : "");
 411
 412         if (sscanf(argv[3], "%d", &priority) != 1 || priority < 1) {
 413                 /* Lookup the priority label */
 414                 if ((priority = ast_findlabel_extension(chan, argv[1], argv[2], argv[3], chan->cid.cid_num)) < 0) {
 415                         ast_log(LOG_ERROR, "Priority '%s' not found in '%s@%s'\n", argv[3], argv[2], argv[1]);
 416                         ast_agi_fdprintf(chan, agi->fd, "200 result=-1 Gosub label not found\n");
 417                         return RESULT_FAILURE;
 418                 }
 419         } else if (!ast_exists_extension(chan, argv[1], argv[2], priority, chan->cid.cid_num)) {
 420                 ast_agi_fdprintf(chan, agi->fd, "200 result=-1 Gosub label not found\n");
 421                 return RESULT_FAILURE;
 422         }
 423
 424         /* Save previous location, since we're going to change it */
 425         ast_copy_string(old_context, chan->context, sizeof(old_context));
 426         ast_copy_string(old_extension, chan->exten, sizeof(old_extension));
 427         old_priority = chan->priority;
 428
 429         if (!(theapp = pbx_findapp("Gosub"))) {
 430                 ast_log(LOG_ERROR, "Gosub() cannot be found in the list of loaded applications\n");
 431                 ast_agi_fdprintf(chan, agi->fd, "503 result=-2 Gosub is not loaded\n");
 432                 return RESULT_FAILURE;
 433         }
 434
 435         /* Apparently, if you run ast_pbx_run on a channel that already has a pbx
 436          * structure, you need to add 1 to the priority to get it to go to the
 437          * right place.  But if it doesn't have a pbx structure, then leaving off
 438          * the 1 is the right thing to do.  See how this code differs when we
 439          * call a Gosub for the CALLEE channel in Dial or Queue.
 440          */
 441         if (argc == 5) {
 442                 asprintf(&gosub_args, "%s,%s,%d(%s)", argv[1], argv[2], priority + 1, argv[4]);
 443         } else {
 444                 asprintf(&gosub_args, "%s,%s,%d", argv[1], argv[2], priority + 1);
 445         }
 446
 447         if (gosub_args) {
 448                 int res;
 449
 450                 ast_debug(1, "Trying gosub with arguments '%s'\n", gosub_args);
 451                 ast_copy_string(chan->context, "app_stack_gosub_virtual_context", sizeof(chan->context));
 452                 ast_copy_string(chan->exten, "s", sizeof(chan->exten));
 453                 chan->priority = 0;
 454
 455                 if ((res = pbx_exec(chan, theapp, gosub_args)) == 0) {
 456                         struct ast_pbx *pbx = chan->pbx;
 457                         /* Suppress warning about PBX already existing */
 458                         chan->pbx = NULL;
 459                         ast_agi_fdprintf(chan, agi->fd, "100 result=0 Trying...\n");
 460                         ast_pbx_run(chan);
 461                         ast_agi_fdprintf(chan, agi->fd, "200 result=0 Gosub complete\n");
 462                         if (chan->pbx) {
 463                                 ast_free(chan->pbx);
 464                         }
 465                         chan->pbx = pbx;
 466                 } else {
 467                         ast_agi_fdprintf(chan, agi->fd, "200 result=%d Gosub failed\n", res);
 468                 }
 469                 ast_free(gosub_args);
 470         } else {
 471                 ast_agi_fdprintf(chan, agi->fd, "503 result=-2 Memory allocation failure\n");
 472                 return RESULT_FAILURE;
 473         }
 474
 475         /* Restore previous location */
 476         ast_copy_string(chan->context, old_context, sizeof(chan->context));
 477         ast_copy_string(chan->exten, old_extension, sizeof(chan->exten));
 478         chan->priority = old_priority;
 479
 480         return RESULT_SUCCESS;
 481 }
 482
 483 static char usage_gosub[] =
 484 " Usage: GOSUB <context> <extension> <priority> [<optional-argument>]\n"
 485 "   Cause the channel to execute the specified dialplan subroutine, returning\n"
 486 " to the dialplan with execution of a Return()\n";
 487
 488 struct agi_command gosub_agi_command =
 489         { { "gosub", NULL }, handle_gosub, "Execute a dialplan subroutine", usage_gosub , 0 };
 490
 491 static int unload_module(void)
 492 {
 493         struct ast_context *con;
 494
 495         if (agi_loaded) {
 496                 ast_agi_unregister(ast_module_info->self, &gosub_agi_command);
 497
 498                 if ((con = ast_context_find("app_stack_gosub_virtual_context"))) {
 499                         ast_context_remove_extension2(con, "s", 1, NULL, 0);
 500                         ast_context_destroy(con, "app_stack"); /* leave nothing behind */
 501                 }
 502         }
 503
 504         ast_unregister_application(app_return);
 505         ast_unregister_application(app_pop);
 506         ast_unregister_application(app_gosubif);
 507         ast_unregister_application(app_gosub);
 508         ast_custom_function_unregister(&local_function);
 509
 510         return 0;
 511 }
 512
 513 static int load_module(void)
 514 {
 515         struct ast_context *con;
 516
 517         if (!ast_module_check("res_agi.so")) {
 518                 if (ast_load_resource("res_agi.so") == AST_MODULE_LOAD_SUCCESS) {
 519                         agi_loaded = 1;
 520                 }
 521         } else {
 522                 agi_loaded = 1;
 523         }
 524
 525         if (agi_loaded) {
 526                 con = ast_context_find_or_create(NULL, NULL, "app_stack_gosub_virtual_context", "app_stack");
 527                 if (!con) {
 528                         ast_log(LOG_ERROR, "Virtual context 'app_stack_gosub_virtual_context' does not exist and unable to create\n");
 529                         return AST_MODULE_LOAD_DECLINE;
 530                 } else {
 531                         ast_add_extension2(con, 1, "s", 1, NULL, NULL, "KeepAlive", ast_strdup(""), ast_free_ptr, "app_stack");
 532                 }
 533
 534                 ast_agi_register(ast_module_info->self, &gosub_agi_command);
 535         }
 536
 537         ast_register_application(app_pop, pop_exec, pop_synopsis, pop_descrip);
 538         ast_register_application(app_return, return_exec, return_synopsis, return_descrip);
 539         ast_register_application(app_gosubif, gosubif_exec, gosubif_synopsis, gosubif_descrip);
 540         ast_register_application(app_gosub, gosub_exec, gosub_synopsis, gosub_descrip);
 541         ast_custom_function_register(&local_function);
 542
 543         return 0;
 544 }
 545
 546 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Dialplan subroutines (Gosub, Return, etc)");