Wed Oct 28 11:45:27 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: 211551 $")
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 (!found) {
00104       variables = ast_var_assign(var, "");
00105       AST_LIST_INSERT_HEAD(&frame->varshead, variables, entries);
00106       pbx_builtin_pushvar_helper(chan, var, value);
00107    } else {
00108       pbx_builtin_setvar_helper(chan, var, value);
00109    }
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    return 0;
00118 }
00119 
00120 static void gosub_release_frame(struct ast_channel *chan, struct gosub_stack_frame *frame)
00121 {
00122    struct ast_var_t *vardata;
00123 
00124    /* If chan is not defined, then we're calling it as part of gosub_free,
00125     * and the channel variables will be deallocated anyway.  Otherwise, we're
00126     * just releasing a single frame, so we need to clean up the arguments for
00127     * that frame, so that we re-expose the variables from the previous frame
00128     * that were hidden by this one.
00129     */
00130    while ((vardata = AST_LIST_REMOVE_HEAD(&frame->varshead, entries))) {
00131       if (chan)
00132          pbx_builtin_setvar_helper(chan, ast_var_name(vardata), NULL);  
00133       ast_var_delete(vardata);
00134    }
00135 
00136    ast_free(frame);
00137 }
00138 
00139 static struct gosub_stack_frame *gosub_allocate_frame(const char *context, const char *extension, int priority, unsigned char arguments)
00140 {
00141    struct gosub_stack_frame *new = NULL;
00142    int len_extension = strlen(extension), len_context = strlen(context);
00143 
00144    if ((new = ast_calloc(1, sizeof(*new) + 2 + len_extension + len_context))) {
00145       AST_LIST_HEAD_INIT_NOLOCK(&new->varshead);
00146       strcpy(new->extension, extension);
00147       new->context = new->extension + len_extension + 1;
00148       strcpy(new->context, context);
00149       new->priority = priority;
00150       new->arguments = arguments;
00151    }
00152    return new;
00153 }
00154 
00155 static void gosub_free(void *data)
00156 {
00157    AST_LIST_HEAD(, gosub_stack_frame) *oldlist = data;
00158    struct gosub_stack_frame *oldframe;
00159    AST_LIST_LOCK(oldlist);
00160    while ((oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries))) {
00161       gosub_release_frame(NULL, oldframe);
00162    }
00163    AST_LIST_UNLOCK(oldlist);
00164    AST_LIST_HEAD_DESTROY(oldlist);
00165    ast_free(oldlist);
00166 }
00167 
00168 static int pop_exec(struct ast_channel *chan, void *data)
00169 {
00170    struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
00171    struct gosub_stack_frame *oldframe;
00172    AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
00173 
00174    if (!stack_store) {
00175       ast_log(LOG_WARNING, "%s called with no gosub stack allocated.\n", app_pop);
00176       return 0;
00177    }
00178 
00179    oldlist = stack_store->data;
00180    AST_LIST_LOCK(oldlist);
00181    oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries);
00182    AST_LIST_UNLOCK(oldlist);
00183 
00184    if (oldframe) {
00185       gosub_release_frame(chan, oldframe);
00186    } else {
00187       ast_debug(1, "%s called with an empty gosub stack\n", app_pop);
00188    }
00189    return 0;
00190 }
00191 
00192 static int return_exec(struct ast_channel *chan, void *data)
00193 {
00194    struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
00195    struct gosub_stack_frame *oldframe;
00196    AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
00197    char *retval = data;
00198 
00199    if (!stack_store) {
00200       ast_log(LOG_ERROR, "Return without Gosub: stack is unallocated\n");
00201       return -1;
00202    }
00203 
00204    oldlist = stack_store->data;
00205    AST_LIST_LOCK(oldlist);
00206    oldframe = AST_LIST_REMOVE_HEAD(oldlist, entries);
00207    AST_LIST_UNLOCK(oldlist);
00208 
00209    if (!oldframe) {
00210       ast_log(LOG_ERROR, "Return without Gosub: stack is empty\n");
00211       return -1;
00212    }
00213 
00214    ast_explicit_goto(chan, oldframe->context, oldframe->extension, oldframe->priority);
00215    gosub_release_frame(chan, oldframe);
00216 
00217    /* Set a return value, if any */
00218    pbx_builtin_setvar_helper(chan, "GOSUB_RETVAL", S_OR(retval, ""));
00219    return 0;
00220 }
00221 
00222 static int gosub_exec(struct ast_channel *chan, void *data)
00223 {
00224    struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
00225    AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
00226    struct gosub_stack_frame *newframe;
00227    char argname[15], *tmp = ast_strdupa(data), *label, *endparen;
00228    int i;
00229    AST_DECLARE_APP_ARGS(args2,
00230       AST_APP_ARG(argval)[100];
00231    );
00232 
00233    if (ast_strlen_zero(data)) {
00234       ast_log(LOG_ERROR, "%s requires an argument: %s([[context,]exten,]priority[(arg1[,...][,argN])])\n", app_gosub, app_gosub);
00235       return -1;
00236    }
00237 
00238    if (!stack_store) {
00239       ast_debug(1, "Channel %s has no datastore, so we're allocating one.\n", chan->name);
00240       stack_store = ast_channel_datastore_alloc(&stack_info, NULL);
00241       if (!stack_store) {
00242          ast_log(LOG_ERROR, "Unable to allocate new datastore.  Gosub will fail.\n");
00243          return -1;
00244       }
00245 
00246       oldlist = ast_calloc(1, sizeof(*oldlist));
00247       if (!oldlist) {
00248          ast_log(LOG_ERROR, "Unable to allocate datastore list head.  Gosub will fail.\n");
00249          ast_channel_datastore_free(stack_store);
00250          return -1;
00251       }
00252 
00253       stack_store->data = oldlist;
00254       AST_LIST_HEAD_INIT(oldlist);
00255       ast_channel_datastore_add(chan, stack_store);
00256    }
00257 
00258    /* Separate the arguments from the label */
00259    /* NOTE:  you cannot use ast_app_separate_args for this, because '(' cannot be used as a delimiter. */
00260    label = strsep(&tmp, "(");
00261    if (tmp) {
00262       endparen = strrchr(tmp, ')');
00263       if (endparen)
00264          *endparen = '\0';
00265       else
00266          ast_log(LOG_WARNING, "Ouch.  No closing paren: '%s'?\n", (char *)data);
00267       AST_STANDARD_RAW_ARGS(args2, tmp);
00268    } else
00269       args2.argc = 0;
00270 
00271    /* Create the return address, but don't save it until we know that the Gosub destination exists */
00272    newframe = gosub_allocate_frame(chan->context, chan->exten, chan->priority + 1, args2.argc);
00273 
00274    if (!newframe) {
00275       return -1;
00276    }
00277 
00278    if (ast_parseable_goto(chan, label)) {
00279       ast_log(LOG_ERROR, "Gosub address is invalid: '%s'\n", (char *)data);
00280       ast_free(newframe);
00281       return -1;
00282    }
00283 
00284    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)) {
00285       ast_log(LOG_ERROR, "Attempt to reach a non-existent destination for gosub: (Context:%s, Extension:%s, Priority:%d)\n",
00286             chan->context, chan->exten, chan->priority);
00287       ast_copy_string(chan->context, newframe->context, sizeof(chan->context));
00288       ast_copy_string(chan->exten, newframe->extension, sizeof(chan->exten));
00289       chan->priority = newframe->priority;
00290       ast_free(newframe);
00291       return -1;
00292    }
00293 
00294    /* Now that we know for certain that we're going to a new location, set our arguments */
00295    for (i = 0; i < args2.argc; i++) {
00296       snprintf(argname, sizeof(argname), "ARG%d", i + 1);
00297       frame_set_var(chan, newframe, argname, args2.argval[i]);
00298       ast_debug(1, "Setting '%s' to '%s'\n", argname, args2.argval[i]);
00299    }
00300 
00301    /* And finally, save our return address */
00302    oldlist = stack_store->data;
00303    AST_LIST_LOCK(oldlist);
00304    AST_LIST_INSERT_HEAD(oldlist, newframe, entries);
00305    AST_LIST_UNLOCK(oldlist);
00306 
00307    return 0;
00308 }
00309 
00310 static int gosubif_exec(struct ast_channel *chan, void *data)
00311 {
00312    char *args;
00313    int res=0;
00314    AST_DECLARE_APP_ARGS(cond,
00315       AST_APP_ARG(ition);
00316       AST_APP_ARG(labels);
00317    );
00318    AST_DECLARE_APP_ARGS(label,
00319       AST_APP_ARG(iftrue);
00320       AST_APP_ARG(iffalse);
00321    );
00322 
00323    if (ast_strlen_zero(data)) {
00324       ast_log(LOG_WARNING, "GosubIf requires an argument: GosubIf(cond?label1(args):label2(args)\n");
00325       return 0;
00326    }
00327 
00328    args = ast_strdupa(data);
00329    AST_NONSTANDARD_RAW_ARGS(cond, args, '?');
00330    if (cond.argc != 2) {
00331       ast_log(LOG_WARNING, "GosubIf requires an argument: GosubIf(cond?label1(args):label2(args)\n");
00332       return 0;
00333    }
00334 
00335    AST_NONSTANDARD_RAW_ARGS(label, cond.labels, ':');
00336 
00337    if (pbx_checkcondition(cond.ition)) {
00338       if (!ast_strlen_zero(label.iftrue))
00339          res = gosub_exec(chan, label.iftrue);
00340    } else if (!ast_strlen_zero(label.iffalse)) {
00341       res = gosub_exec(chan, label.iffalse);
00342    }
00343 
00344    return res;
00345 }
00346 
00347 static int local_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
00348 {
00349    struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
00350    AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
00351    struct gosub_stack_frame *frame;
00352    struct ast_var_t *variables;
00353 
00354    if (!stack_store)
00355       return -1;
00356 
00357    oldlist = stack_store->data;
00358    AST_LIST_LOCK(oldlist);
00359    if (!(frame = AST_LIST_FIRST(oldlist))) {
00360       /* Not within a Gosub routine */
00361       AST_LIST_UNLOCK(oldlist);
00362       return -1;
00363    }
00364 
00365    AST_LIST_TRAVERSE(&frame->varshead, variables, entries) {
00366       if (!strcmp(data, ast_var_name(variables))) {
00367          const char *tmp = pbx_builtin_getvar_helper(chan, data);
00368          ast_copy_string(buf, S_OR(tmp, ""), len);
00369          break;
00370       }
00371    }
00372    AST_LIST_UNLOCK(oldlist);
00373    return 0;
00374 }
00375 
00376 static int local_write(struct ast_channel *chan, const char *cmd, char *var, const char *value)
00377 {
00378    struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
00379    AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
00380    struct gosub_stack_frame *frame;
00381 
00382    if (!stack_store) {
00383       ast_log(LOG_ERROR, "Tried to set LOCAL(%s), but we aren't within a Gosub routine\n", var);
00384       return -1;
00385    }
00386 
00387    oldlist = stack_store->data;
00388    AST_LIST_LOCK(oldlist);
00389    frame = AST_LIST_FIRST(oldlist);
00390 
00391    if (frame)
00392       frame_set_var(chan, frame, var, value);
00393 
00394    AST_LIST_UNLOCK(oldlist);
00395 
00396    return 0;
00397 }
00398 
00399 static struct ast_custom_function local_function = {
00400    .name = "LOCAL",
00401    .synopsis = "Variables local to the gosub stack frame",
00402    .syntax = "LOCAL(<varname>)",
00403    .write = local_write,
00404    .read = local_read,
00405 };
00406 
00407 static int handle_gosub(struct ast_channel *chan, AGI *agi, int argc, char **argv)
00408 {
00409    int old_priority, priority;
00410    char old_context[AST_MAX_CONTEXT], old_extension[AST_MAX_EXTENSION];
00411    struct ast_app *theapp;
00412    char *gosub_args;
00413 
00414    if (argc < 4 || argc > 5) {
00415       return RESULT_SHOWUSAGE;
00416    }
00417 
00418    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] : "");
00419 
00420    if (sscanf(argv[3], "%30d", &priority) != 1 || priority < 1) {
00421       /* Lookup the priority label */
00422       if ((priority = ast_findlabel_extension(chan, argv[1], argv[2], argv[3], chan->cid.cid_num)) < 0) {
00423          ast_log(LOG_ERROR, "Priority '%s' not found in '%s@%s'\n", argv[3], argv[2], argv[1]);
00424          ast_agi_send(agi->fd, chan, "200 result=-1 Gosub label not found\n");
00425          return RESULT_FAILURE;
00426       }
00427    } else if (!ast_exists_extension(chan, argv[1], argv[2], priority, chan->cid.cid_num)) {
00428       ast_agi_send(agi->fd, chan, "200 result=-1 Gosub label not found\n");
00429       return RESULT_FAILURE;
00430    }
00431 
00432    /* Save previous location, since we're going to change it */
00433    ast_copy_string(old_context, chan->context, sizeof(old_context));
00434    ast_copy_string(old_extension, chan->exten, sizeof(old_extension));
00435    old_priority = chan->priority;
00436 
00437    if (!(theapp = pbx_findapp("Gosub"))) {
00438       ast_log(LOG_ERROR, "Gosub() cannot be found in the list of loaded applications\n");
00439       ast_agi_send(agi->fd, chan, "503 result=-2 Gosub is not loaded\n");
00440       return RESULT_FAILURE;
00441    }
00442 
00443    /* Apparently, if you run ast_pbx_run on a channel that already has a pbx
00444     * structure, you need to add 1 to the priority to get it to go to the
00445     * right place.  But if it doesn't have a pbx structure, then leaving off
00446     * the 1 is the right thing to do.  See how this code differs when we
00447     * call a Gosub for the CALLEE channel in Dial or Queue.
00448     */
00449    if (argc == 5) {
00450       if (asprintf(&gosub_args, "%s,%s,%d(%s)", argv[1], argv[2], priority + 1, argv[4]) < 0) {
00451          ast_log(LOG_WARNING, "asprintf() failed: %s\n", strerror(errno));
00452          gosub_args = NULL;
00453       }
00454    } else {
00455       if (asprintf(&gosub_args, "%s,%s,%d", argv[1], argv[2], priority + 1) < 0) {
00456          ast_log(LOG_WARNING, "asprintf() failed: %s\n", strerror(errno));
00457          gosub_args = NULL;
00458       }
00459    }
00460 
00461    if (gosub_args) {
00462       int res;
00463 
00464       ast_debug(1, "Trying gosub with arguments '%s'\n", gosub_args);
00465       ast_copy_string(chan->context, "app_stack_gosub_virtual_context", sizeof(chan->context));
00466       ast_copy_string(chan->exten, "s", sizeof(chan->exten));
00467       chan->priority = 0;
00468 
00469       if ((res = pbx_exec(chan, theapp, gosub_args)) == 0) {
00470          struct ast_pbx *pbx = chan->pbx;
00471          struct ast_pbx_args args;
00472          memset(&args, 0, sizeof(args));
00473          args.no_hangup_chan = 1;
00474          /* Suppress warning about PBX already existing */
00475          chan->pbx = NULL;
00476          ast_agi_send(agi->fd, chan, "100 result=0 Trying...\n");
00477          ast_pbx_run_args(chan, &args);
00478          ast_agi_send(agi->fd, chan, "200 result=0 Gosub complete\n");
00479          if (chan->pbx) {
00480             ast_free(chan->pbx);
00481          }
00482          chan->pbx = pbx;
00483       } else {
00484          ast_agi_send(agi->fd, chan, "200 result=%d Gosub failed\n", res);
00485       }
00486       ast_free(gosub_args);
00487    } else {
00488       ast_agi_send(agi->fd, chan, "503 result=-2 Memory allocation failure\n");
00489       return RESULT_FAILURE;
00490    }
00491 
00492    /* Restore previous location */
00493    ast_copy_string(chan->context, old_context, sizeof(chan->context));
00494    ast_copy_string(chan->exten, old_extension, sizeof(chan->exten));
00495    chan->priority = old_priority;
00496 
00497    return RESULT_SUCCESS;
00498 }
00499 
00500 static char usage_gosub[] =
00501 " Usage: GOSUB <context> <extension> <priority> [<optional-argument>]\n"
00502 "   Cause the channel to execute the specified dialplan subroutine, returning\n"
00503 " to the dialplan with execution of a Return()\n";
00504 
00505 struct agi_command gosub_agi_command =
00506    { { "gosub", NULL }, handle_gosub, "Execute a dialplan subroutine", usage_gosub , 0 };
00507 
00508 static int unload_module(void)
00509 {
00510    if (ast_agi_unregister) {
00511       ast_agi_unregister(ast_module_info->self, &gosub_agi_command);
00512    }
00513 
00514    ast_unregister_application(app_return);
00515    ast_unregister_application(app_pop);
00516    ast_unregister_application(app_gosubif);
00517    ast_unregister_application(app_gosub);
00518    ast_custom_function_unregister(&local_function);
00519 
00520    return 0;
00521 }
00522 
00523 static int load_module(void)
00524 {
00525    /* usage of AGI is optional, so check to see if the ast_agi_register()
00526       function is available; if so, use it.
00527    */
00528    if (ast_agi_register) {
00529       ast_agi_register(ast_module_info->self, &gosub_agi_command);
00530    }
00531 
00532    ast_register_application(app_pop, pop_exec, pop_synopsis, pop_descrip);
00533    ast_register_application(app_return, return_exec, return_synopsis, return_descrip);
00534    ast_register_application(app_gosubif, gosubif_exec, gosubif_synopsis, gosubif_descrip);
00535    ast_register_application(app_gosub, gosub_exec, gosub_synopsis, gosub_descrip);
00536    ast_custom_function_register(&local_function);
00537 
00538    return 0;
00539 }
00540 
00541 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Dialplan subroutines (Gosub, Return, etc)");

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