Fri Jun 19 12:09:29 2009

Asterisk developer's documentation


app_stack.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (c) 2004-2006 Tilghman Lesher <app_stack_v003@the-tilghman.com>.
00005  *
00006  * This code is released by the author with no restrictions on usage.
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*! \file
00020  *
00021  * \brief Stack applications Gosub, Return, etc.
00022  *
00023  * \author Tilghman Lesher <app_stack_v003@the-tilghman.com>
00024  * 
00025  * \ingroup applications
00026  */
00027 
00028 /*** MODULEINFO
00029    <use>res_agi</use>
00030  ***/
00031 
00032 #include "asterisk.h"
00033  
00034 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 174504 $")
00035 
00036 #include "asterisk/pbx.h"
00037 #include "asterisk/module.h"
00038 #include "asterisk/app.h"
00039 #include "asterisk/manager.h"
00040 #include "asterisk/channel.h"
00041 
00042 /* usage of AGI is optional, so indicate that to the header file */
00043 #define ASTERISK_AGI_OPTIONAL
00044 #include "asterisk/agi.h"
00045 
00046 
00047 static const char *app_gosub = "Gosub";
00048 static const char *app_gosubif = "GosubIf";
00049 static const char *app_return = "Return";
00050 static const char *app_pop = "StackPop";
00051 
00052 static const char *gosub_synopsis = "Jump to label, saving return address";
00053 static const char *gosubif_synopsis = "Conditionally jump to label, saving return address";
00054 static const char *return_synopsis = "Return from gosub routine";
00055 static const char *pop_synopsis = "Remove one address from gosub stack";
00056 
00057 static const char *gosub_descrip =
00058 "  Gosub([[context,]exten,]priority[(arg1[,...][,argN])]):\n"
00059 "Jumps to the label specified, saving the return address.\n";
00060 static const char *gosubif_descrip =
00061 "  GosubIf(condition?labeliftrue[(arg1[,...])][:labeliffalse[(arg1[,...])]]):\n"
00062 "If the condition is true, then jump to labeliftrue.  If false, jumps to\n"
00063 "labeliffalse, if specified.  In either case, a jump saves the return point\n"
00064 "in the dialplan, to be returned to with a Return.\n";
00065 static const char *return_descrip =
00066 "  Return([return-value]):\n"
00067 "Jumps to the last label on the stack, removing it.  The return value, if\n"
00068 "any, is saved in the channel variable GOSUB_RETVAL.\n";
00069 static const char *pop_descrip =
00070 "  StackPop():\n"
00071 "Removes last label on the stack, discarding it.\n";
00072 
00073 static void gosub_free(void *data);
00074 
00075 static struct ast_datastore_info stack_info = {
00076    .type = "GOSUB",
00077    .destroy = gosub_free,
00078 };
00079 
00080 struct gosub_stack_frame {
00081    AST_LIST_ENTRY(gosub_stack_frame) entries;
00082    /* 100 arguments is all that we support anyway, but this will handle up to 255 */
00083    unsigned char arguments;
00084    struct varshead varshead;
00085    int priority;
00086    char *context;
00087    char extension[0];
00088 };
00089 
00090 static int frame_set_var(struct ast_channel *chan, struct gosub_stack_frame *frame, const char *var, const char *value)
00091 {
00092    struct ast_var_t *variables;
00093    int found = 0;
00094 
00095    /* Does this variable already exist? */
00096    AST_LIST_TRAVERSE(&frame->varshead, variables, entries) {
00097       if (!strcmp(var, ast_var_name(variables))) {
00098          found = 1;
00099          break;
00100       }
00101    }
00102 
00103    if (!ast_strlen_zero(value)) {
00104       if (!found) {
00105          variables = ast_var_assign(var, "");
00106          AST_LIST_INSERT_HEAD(&frame->varshead, variables, entries);
00107          pbx_builtin_pushvar_helper(chan, var, value);
00108       } else
00109          pbx_builtin_setvar_helper(chan, var, value);
00110 
00111       manager_event(EVENT_FLAG_DIALPLAN, "VarSet", 
00112          "Channel: %s\r\n"
00113          "Variable: LOCAL(%s)\r\n"
00114          "Value: %s\r\n"
00115          "Uniqueid: %s\r\n", 
00116          chan->name, var, value, chan->uniqueid);
00117    }
00118    return 0;
00119 }
00120 
00121 static void gosub_release_frame(struct ast_channel *chan, struct gosub_stack_frame *frame)
00122 {
00123    struct ast_var_t *vardata;
00124 
00125    /* If chan is not defined, then we're calling it as part of gosub_free,
00126     * and the channel variables will be deallocated anyway.  Otherwise, we're
00127     * just releasing a single frame, so we need to clean up the arguments for
00128     * that frame, so that we re-expose the variables from the previous frame
00129     * that were hidden by this one.
00130     */
00131    while ((vardata = AST_LIST_REMOVE_HEAD(&frame->varshead, entries))) {
00132       if (chan)
00133          pbx_builtin_setvar_helper(chan, ast_var_name(vardata), NULL);  
00134       ast_var_delete(vardata);
00135    }
00136 
00137    ast_free(frame);
00138 }
00139 
00140 static struct gosub_stack_frame *gosub_allocate_frame(const char *context, const char *extension, int priority, unsigned char arguments)
00141 {
00142    struct gosub_stack_frame *new = NULL;
00143    int len_extension = strlen(extension), len_context = strlen(context);
00144 
00145    if ((new = ast_calloc(1, sizeof(*new) + 2 + len_extension + len_context))) {
00146       AST_LIST_HEAD_INIT_NOLOCK(&new->varshead);
00147       strcpy(new->extension, extension);
00148       new->context = new->extension + len_extension + 1;
00149       strcpy(new->context, context);
00150       new->priority = priority;
00151       new->arguments = arguments;
00152    }
00153    return new;
00154 }
00155 
00156 static void gosub_free(void *data)
00157 {
00158    AST_LIST_HEAD(, gosub_stack_frame) *oldlist = data;
00159    struct gosub_stack_frame *oldframe;
00160    AST_LIST_LOCK(oldlist);
00161    while ((oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries))) {
00162       gosub_release_frame(NULL, oldframe);
00163    }
00164    AST_LIST_UNLOCK(oldlist);
00165    AST_LIST_HEAD_DESTROY(oldlist);
00166    ast_free(oldlist);
00167 }
00168 
00169 static int pop_exec(struct ast_channel *chan, void *data)
00170 {
00171    struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
00172    struct gosub_stack_frame *oldframe;
00173    AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
00174 
00175    if (!stack_store) {
00176       ast_log(LOG_WARNING, "%s called with no gosub stack allocated.\n", app_pop);
00177       return 0;
00178    }
00179 
00180    oldlist = stack_store->data;
00181    AST_LIST_LOCK(oldlist);
00182    oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries);
00183    AST_LIST_UNLOCK(oldlist);
00184 
00185    if (oldframe) {
00186       gosub_release_frame(chan, oldframe);
00187    } else {
00188       ast_debug(1, "%s called with an empty gosub stack\n", app_pop);
00189    }
00190    return 0;
00191 }
00192 
00193 static int return_exec(struct ast_channel *chan, void *data)
00194 {
00195    struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
00196    struct gosub_stack_frame *oldframe;
00197    AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
00198    char *retval = data;
00199 
00200    if (!stack_store) {
00201       ast_log(LOG_ERROR, "Return without Gosub: stack is unallocated\n");
00202       return -1;
00203    }
00204 
00205    oldlist = stack_store->data;
00206    AST_LIST_LOCK(oldlist);
00207    oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries);
00208    AST_LIST_UNLOCK(oldlist);
00209 
00210    if (!oldframe) {
00211       ast_log(LOG_ERROR, "Return without Gosub: stack is empty\n");
00212       return -1;
00213    }
00214 
00215    ast_explicit_goto(chan, oldframe->context, oldframe->extension, oldframe->priority);
00216    gosub_release_frame(chan, oldframe);
00217 
00218    /* Set a return value, if any */
00219    pbx_builtin_setvar_helper(chan, "GOSUB_RETVAL", S_OR(retval, ""));
00220    return 0;
00221 }
00222 
00223 static int gosub_exec(struct ast_channel *chan, void *data)
00224 {
00225    struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
00226    AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
00227    struct gosub_stack_frame *newframe;
00228    char argname[15], *tmp = ast_strdupa(data), *label, *endparen;
00229    int i;
00230    AST_DECLARE_APP_ARGS(args2,
00231       AST_APP_ARG(argval)[100];
00232    );
00233 
00234    if (ast_strlen_zero(data)) {
00235       ast_log(LOG_ERROR, "%s requires an argument: %s([[context,]exten,]priority[(arg1[,...][,argN])])\n", app_gosub, app_gosub);
00236       return -1;
00237    }
00238 
00239    if (!stack_store) {
00240       ast_debug(1, "Channel %s has no datastore, so we're allocating one.\n", chan->name);
00241       stack_store = ast_datastore_alloc(&stack_info, NULL);
00242       if (!stack_store) {
00243          ast_log(LOG_ERROR, "Unable to allocate new datastore.  Gosub will fail.\n");
00244          return -1;
00245       }
00246 
00247       oldlist = ast_calloc(1, sizeof(*oldlist));
00248       if (!oldlist) {
00249          ast_log(LOG_ERROR, "Unable to allocate datastore list head.  Gosub will fail.\n");
00250          ast_datastore_free(stack_store);
00251          return -1;
00252       }
00253 
00254       stack_store->data = oldlist;
00255       AST_LIST_HEAD_INIT(oldlist);
00256       ast_channel_datastore_add(chan, stack_store);
00257    }
00258 
00259    /* Separate the arguments from the label */
00260    /* NOTE:  you cannot use ast_app_separate_args for this, because '(' cannot be used as a delimiter. */
00261    label = strsep(&tmp, "(");
00262    if (tmp) {
00263       endparen = strrchr(tmp, ')');
00264       if (endparen)
00265          *endparen = '\0';
00266       else
00267          ast_log(LOG_WARNING, "Ouch.  No closing paren: '%s'?\n", (char *)data);
00268       AST_STANDARD_APP_ARGS(args2, tmp);
00269    } else
00270       args2.argc = 0;
00271 
00272    /* Create the return address, but don't save it until we know that the Gosub destination exists */
00273    newframe = gosub_allocate_frame(chan->context, chan->exten, chan->priority + 1, args2.argc);
00274 
00275    if (!newframe) {
00276       return -1;
00277    }
00278 
00279    if (ast_parseable_goto(chan, label)) {
00280       ast_log(LOG_ERROR, "Gosub address is invalid: '%s'\n", (char *)data);
00281       ast_free(newframe);
00282       return -1;
00283    }
00284 
00285    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)) {
00286       ast_log(LOG_ERROR, "Attempt to reach a non-existent destination for gosub: (Context:%s, Extension:%s, Priority:%d)\n",
00287             chan->context, chan->exten, chan->priority);
00288       ast_copy_string(chan->context, newframe->context, sizeof(chan->context));
00289       ast_copy_string(chan->exten, newframe->extension, sizeof(chan->exten));
00290       chan->priority = newframe->priority;
00291       ast_free(newframe);
00292       return -1;
00293    }
00294 
00295    /* Now that we know for certain that we're going to a new location, set our arguments */
00296    for (i = 0; i < args2.argc; i++) {
00297       snprintf(argname, sizeof(argname), "ARG%d", i + 1);
00298       frame_set_var(chan, newframe, argname, args2.argval[i]);
00299       ast_debug(1, "Setting '%s' to '%s'\n", argname, args2.argval[i]);
00300    }
00301 
00302    /* And finally, save our return address */
00303    oldlist = stack_store->data;
00304    AST_LIST_LOCK(oldlist);
00305    AST_LIST_INSERT_HEAD(oldlist, newframe, entries);
00306    AST_LIST_UNLOCK(oldlist);
00307 
00308    return 0;
00309 }
00310 
00311 static int gosubif_exec(struct ast_channel *chan, void *data)
00312 {
00313    char *args;
00314    int res=0;
00315    AST_DECLARE_APP_ARGS(cond,
00316       AST_APP_ARG(ition);
00317       AST_APP_ARG(labels);
00318    );
00319    AST_DECLARE_APP_ARGS(label,
00320       AST_APP_ARG(iftrue);
00321       AST_APP_ARG(iffalse);
00322    );
00323 
00324    if (ast_strlen_zero(data)) {
00325       ast_log(LOG_WARNING, "GosubIf requires an argument: GosubIf(cond?label1(args):label2(args)\n");
00326       return 0;
00327    }
00328 
00329    args = ast_strdupa(data);
00330    AST_NONSTANDARD_APP_ARGS(cond, args, '?');
00331    if (cond.argc != 2) {
00332       ast_log(LOG_WARNING, "GosubIf requires an argument: GosubIf(cond?label1(args):label2(args)\n");
00333       return 0;
00334    }
00335 
00336    AST_NONSTANDARD_APP_ARGS(label, cond.labels, ':');
00337 
00338    if (pbx_checkcondition(cond.ition)) {
00339       if (!ast_strlen_zero(label.iftrue))
00340          res = gosub_exec(chan, label.iftrue);
00341    } else if (!ast_strlen_zero(label.iffalse)) {
00342       res = gosub_exec(chan, label.iffalse);
00343    }
00344 
00345    return res;
00346 }
00347 
00348 static int local_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
00349 {
00350    struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
00351    AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
00352    struct gosub_stack_frame *frame;
00353    struct ast_var_t *variables;
00354 
00355    if (!stack_store)
00356       return -1;
00357 
00358    oldlist = stack_store->data;
00359    AST_LIST_LOCK(oldlist);
00360    frame = AST_LIST_FIRST(oldlist);
00361    AST_LIST_TRAVERSE(&frame->varshead, variables, entries) {
00362       if (!strcmp(data, ast_var_name(variables))) {
00363          const char *tmp;
00364          ast_channel_lock(chan);
00365          tmp = pbx_builtin_getvar_helper(chan, data);
00366          ast_copy_string(buf, S_OR(tmp, ""), len);
00367          ast_channel_unlock(chan);
00368          break;
00369       }
00370    }
00371    AST_LIST_UNLOCK(oldlist);
00372    return 0;
00373 }
00374 
00375 static int local_write(struct ast_channel *chan, const char *cmd, char *var, const char *value)
00376 {
00377    struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
00378    AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
00379    struct gosub_stack_frame *frame;
00380 
00381    if (!stack_store) {
00382       ast_log(LOG_ERROR, "Tried to set LOCAL(%s), but we aren't within a Gosub routine\n", var);
00383       return -1;
00384    }
00385 
00386    oldlist = stack_store->data;
00387    AST_LIST_LOCK(oldlist);
00388    frame = AST_LIST_FIRST(oldlist);
00389 
00390    if (frame)
00391       frame_set_var(chan, frame, var, value);
00392 
00393    AST_LIST_UNLOCK(oldlist);
00394 
00395    return 0;
00396 }
00397 
00398 static struct ast_custom_function local_function = {
00399    .name = "LOCAL",
00400    .synopsis = "Variables local to the gosub stack frame",
00401    .syntax = "LOCAL(<varname>)",
00402    .write = local_write,
00403    .read = local_read,
00404 };
00405 
00406 static int handle_gosub(struct ast_channel *chan, AGI *agi, int argc, char **argv)
00407 {
00408    int old_priority, priority;
00409    char old_context[AST_MAX_CONTEXT], old_extension[AST_MAX_EXTENSION];
00410    struct ast_app *theapp;
00411    char *gosub_args;
00412 
00413    if (argc < 4 || argc > 5) {
00414       return RESULT_SHOWUSAGE;
00415    }
00416 
00417    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] : "");
00418 
00419    if (sscanf(argv[3], "%d", &priority) != 1 || priority < 1) {
00420       /* Lookup the priority label */
00421       if ((priority = ast_findlabel_extension(chan, argv[1], argv[2], argv[3], chan->cid.cid_num)) < 0) {
00422          ast_log(LOG_ERROR, "Priority '%s' not found in '%s@%s'\n", argv[3], argv[2], argv[1]);
00423          ast_agi_send(agi->fd, chan, "200 result=-1 Gosub label not found\n");
00424          return RESULT_FAILURE;
00425       }
00426    } else if (!ast_exists_extension(chan, argv[1], argv[2], priority, chan->cid.cid_num)) {
00427       ast_agi_send(agi->fd, chan, "200 result=-1 Gosub label not found\n");
00428       return RESULT_FAILURE;
00429    }
00430 
00431    /* Save previous location, since we're going to change it */
00432    ast_copy_string(old_context, chan->context, sizeof(old_context));
00433    ast_copy_string(old_extension, chan->exten, sizeof(old_extension));
00434    old_priority = chan->priority;
00435 
00436    if (!(theapp = pbx_findapp("Gosub"))) {
00437       ast_log(LOG_ERROR, "Gosub() cannot be found in the list of loaded applications\n");
00438       ast_agi_send(agi->fd, chan, "503 result=-2 Gosub is not loaded\n");
00439       return RESULT_FAILURE;
00440    }
00441 
00442    /* Apparently, if you run ast_pbx_run on a channel that already has a pbx
00443     * structure, you need to add 1 to the priority to get it to go to the
00444     * right place.  But if it doesn't have a pbx structure, then leaving off
00445     * the 1 is the right thing to do.  See how this code differs when we
00446     * call a Gosub for the CALLEE channel in Dial or Queue.
00447     */
00448    if (argc == 5) {
00449       if (asprintf(&gosub_args, "%s,%s,%d(%s)", argv[1], argv[2], priority + 1, argv[4]) < 0) {
00450          ast_log(LOG_WARNING, "asprintf() failed: %s\n", strerror(errno));
00451          gosub_args = NULL;
00452       }
00453    } else {
00454       if (asprintf(&gosub_args, "%s,%s,%d", argv[1], argv[2], priority + 1) < 0) {
00455          ast_log(LOG_WARNING, "asprintf() failed: %s\n", strerror(errno));
00456          gosub_args = NULL;
00457       }
00458    }
00459 
00460    if (gosub_args) {
00461       int res;
00462 
00463       ast_debug(1, "Trying gosub with arguments '%s'\n", gosub_args);
00464 
00465       if ((res = pbx_exec(chan, theapp, gosub_args)) == 0) {
00466          struct ast_pbx *pbx = chan->pbx;
00467          struct ast_pbx_args args;
00468          memset(&args, 0, sizeof(args));
00469          args.no_hangup_chan = 1;
00470          /* Suppress warning about PBX already existing */
00471          chan->pbx = NULL;
00472          ast_agi_send(agi->fd, chan, "100 result=0 Trying...\n");
00473          ast_pbx_run_args(chan, &args);
00474          ast_agi_send(agi->fd, chan, "200 result=0 Gosub complete\n");
00475          if (chan->pbx) {
00476             ast_free(chan->pbx);
00477          }
00478          chan->pbx = pbx;
00479       } else {
00480          ast_agi_send(agi->fd, chan, "200 result=%d Gosub failed\n", res);
00481       }
00482       ast_free(gosub_args);
00483    } else {
00484       ast_agi_send(agi->fd, chan, "503 result=-2 Memory allocation failure\n");
00485       return RESULT_FAILURE;
00486    }
00487 
00488    /* Restore previous location */
00489    ast_copy_string(chan->context, old_context, sizeof(chan->context));
00490    ast_copy_string(chan->exten, old_extension, sizeof(chan->exten));
00491    chan->priority = old_priority;
00492 
00493    return RESULT_SUCCESS;
00494 }
00495 
00496 static char usage_gosub[] =
00497 " Usage: GOSUB <context> <extension> <priority> [<optional-argument>]\n"
00498 "   Cause the channel to execute the specified dialplan subroutine, returning\n"
00499 " to the dialplan with execution of a Return()\n";
00500 
00501 struct agi_command gosub_agi_command =
00502    { { "gosub", NULL }, handle_gosub, "Execute a dialplan subroutine", usage_gosub , 0 };
00503 
00504 static int unload_module(void)
00505 {
00506    if (ast_agi_unregister) {
00507        ast_agi_unregister(ast_module_info->self, &gosub_agi_command);
00508    }
00509 
00510    ast_unregister_application(app_return);
00511    ast_unregister_application(app_pop);
00512    ast_unregister_application(app_gosubif);
00513    ast_unregister_application(app_gosub);
00514    ast_custom_function_unregister(&local_function);
00515 
00516    return 0;
00517 }
00518 
00519 static int load_module(void)
00520 {
00521    /* usage of AGI is optional, so check to see if the ast_agi_register()
00522       function is available; if so, use it.
00523    */
00524    if (ast_agi_register) {
00525       ast_agi_register(ast_module_info->self, &gosub_agi_command);
00526    }
00527 
00528    ast_register_application(app_pop, pop_exec, pop_synopsis, pop_descrip);
00529    ast_register_application(app_return, return_exec, return_synopsis, return_descrip);
00530    ast_register_application(app_gosubif, gosubif_exec, gosubif_synopsis, gosubif_descrip);
00531    ast_register_application(app_gosub, gosub_exec, gosub_synopsis, gosub_descrip);
00532    ast_custom_function_register(&local_function);
00533 
00534    return 0;
00535 }
00536 
00537 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Dialplan subroutines (Gosub, Return, etc)");

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