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