app_if.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright 2021, Naveen Albert <[email protected]>
 *
 * Naveen Albert <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief If Branch Implementation
 *
 * \author Naveen Albert <[email protected]>
 *
 * \ingroup applications
 */

/*** MODULEINFO
 <support_level>extended</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/pbx.h"
#include "asterisk/module.h"
#include "asterisk/channel.h"

/*** DOCUMENTATION
 <application name="If" language="en_US">
 <synopsis>
 Start an if branch.
 </synopsis>
 <syntax>
 <parameter name="expr" required="true" />
 </syntax>
 <description>
 <para>Start an If branch. Execution will continue inside the branch
 if expr is true.</para>
 </description>
 <see-also>
 <ref type="application">EndIf</ref>
 <ref type="application">ExitIf</ref>
 </see-also>
 </application>
 <application name="EndIf" language="en_US">
 <synopsis>
 End an if branch.
 </synopsis>
 <syntax />
 <description>
 <para>Ends the branch begun by the preceding <literal>If()</literal> application.</para>
 </description>
 <see-also>
 <ref type="application">If</ref>
 <ref type="application">ExitIf</ref>
 </see-also>
 </application>
 <application name="ExitIf" language="en_US">
 <synopsis>
 End an If branch.
 </synopsis>
 <syntax />
 <description>
 <para>Exits an <literal>If()</literal> branch, whether or not it has completed.</para>
 </description>
 <see-also>
 <ref type="application">If</ref>
 <ref type="application">EndIf</ref>
 </see-also>
 </application>
 ***/

static char *start_app = "If";
static char *stop_app = "EndIf";
static char *exit_app = "ExitIf";

#define VAR_SIZE 64


static const char *get_index(struct ast_channel *chan, const char *prefix, int idx) {
 char varname[VAR_SIZE];

 snprintf(varname, VAR_SIZE, "%s_%d", prefix, idx);
 return pbx_builtin_getvar_helper(chan, varname);
}

static struct ast_exten *find_matching_priority(struct ast_context *c, const char *exten, int priority, const char *callerid)
{
 struct ast_exten *e;
 struct ast_context *c2;
 int idx;

 for (e=ast_walk_context_extensions(c, NULL); e; e=ast_walk_context_extensions(c, e)) {
 if (ast_extension_match(ast_get_extension_name(e), exten)) {
 int needmatch = ast_get_extension_matchcid(e);
 if ((needmatch && ast_extension_match(ast_get_extension_cidmatch(e), callerid)) ||
 (!needmatch)) {
 /* This is the matching extension we want */
 struct ast_exten *p;
 for (p=ast_walk_extension_priorities(e, NULL); p; p=ast_walk_extension_priorities(e, p)) {
 if (priority != ast_get_extension_priority(p))
 continue;
 return p;
 }
 }
 }
 }

 /* No match; run through includes */
 for (idx = 0; idx < ast_context_includes_count(c); idx++) {
 const struct ast_include *i = ast_context_includes_get(c, idx);

 for (c2=ast_walk_contexts(NULL); c2; c2=ast_walk_contexts(c2)) {
 if (!strcmp(ast_get_context_name(c2), ast_get_include_name(i))) {
 e = find_matching_priority(c2, exten, priority, callerid);
 if (e)
 return e;
 }
 }
 }
 return NULL;
}

static int find_matching_endif(struct ast_channel *chan)
{
 struct ast_context *c;
 int res = -1;

 if (ast_rdlock_contexts()) {
 ast_log(LOG_ERROR, "Failed to lock contexts list\n");
 return -1;
 }

 for (c=ast_walk_contexts(NULL); c; c=ast_walk_contexts(c)) {
 struct ast_exten *e;

 if (!ast_rdlock_context(c)) {
 if (!strcmp(ast_get_context_name(c), ast_channel_context(chan))) {
 /* This is the matching context we want */
 int cur_priority = ast_channel_priority(chan) + 1, level=1;

 for (e = find_matching_priority(c, ast_channel_exten(chan), cur_priority,
 S_COR(ast_channel_caller(chan)->id.number.valid, ast_channel_caller(chan)->id.number.str, NULL));
 e;
 e = find_matching_priority(c, ast_channel_exten(chan), ++cur_priority,
 S_COR(ast_channel_caller(chan)->id.number.valid, ast_channel_caller(chan)->id.number.str, NULL))) {
 if (!strcasecmp(ast_get_extension_app(e), "IF")) {
 level++;
 } else if (!strcasecmp(ast_get_extension_app(e), "ENDIF")) {
 level--;
 }

 if (level == 0) {
 res = cur_priority;
 break;
 }
 }
 }
 ast_unlock_context(c);
 if (res > 0) {
 break;
 }
 }
 }
 ast_unlock_contexts();
 return res;
}

static int _if_exec(struct ast_channel *chan, const char *data, int end)
{
 int res=0;
 const char *if_pri = NULL;
 char *my_name = NULL;
 const char *condition = NULL, *label = NULL;
 char varname[VAR_SIZE], end_varname[VAR_SIZE];
 const char *prefix = "IF";
 size_t size=0;
 int used_index_i = -1, x=0;
 char used_index[VAR_SIZE] = "0", new_index[VAR_SIZE] = "0";

 if (!chan) {
 return -1;
 }

 for (x=0;;x++) {
 if (get_index(chan, prefix, x)) {
 used_index_i = x;
 } else
 break;
 }

 snprintf(used_index, VAR_SIZE, "%d", used_index_i);
 snprintf(new_index, VAR_SIZE, "%d", used_index_i + 1);

 if (!end)
 condition = ast_strdupa(data);

 size = strlen(ast_channel_context(chan)) + strlen(ast_channel_exten(chan)) + 32;
 my_name = ast_alloca(size);
 memset(my_name, 0, size);
 snprintf(my_name, size, "%s_%s_%d", ast_channel_context(chan), ast_channel_exten(chan), ast_channel_priority(chan));

 ast_channel_lock(chan);
 if (end) {
 label = used_index;
 } else if (!(label = pbx_builtin_getvar_helper(chan, my_name))) {
 label = new_index;
 pbx_builtin_setvar_helper(chan, my_name, label);
 }
 snprintf(varname, VAR_SIZE, "%s_%s", prefix, label);
 if ((if_pri = pbx_builtin_getvar_helper(chan, varname)) && !end) {
 if_pri = ast_strdupa(if_pri);
 snprintf(end_varname,VAR_SIZE,"END_%s",varname);
 }
 ast_channel_unlock(chan);

 if ((!end && !pbx_checkcondition(condition)) || (end > 0)) {
 /* Condition Met (clean up helper vars) */
 const char *goto_str;
 pbx_builtin_setvar_helper(chan, varname, NULL);
 pbx_builtin_setvar_helper(chan, my_name, NULL);
 snprintf(end_varname,VAR_SIZE,"END_%s",varname);
 ast_channel_lock(chan);
 if ((goto_str = pbx_builtin_getvar_helper(chan, end_varname))) {
 ast_parseable_goto(chan, goto_str);
 pbx_builtin_setvar_helper(chan, end_varname, NULL);
 } else {
 int pri = find_matching_endif(chan);
 if (pri > 0) {
 ast_verb(3, "Jumping to priority %d\n", pri);
 ast_channel_priority_set(chan, pri);
 } else if (end == 2) { /* Condition added because of end > 0 instead of end == 2 */
 ast_log(LOG_WARNING, "Couldn't find matching EndIf? (If at %s@%s priority %d)\n", ast_channel_context(chan), ast_channel_exten(chan), ast_channel_priority(chan));
 }
 }
 ast_channel_unlock(chan);
 return res;
 }

 if (!end && !if_pri) {
 char *goto_str;
 size = strlen(ast_channel_context(chan)) + strlen(ast_channel_exten(chan)) + 32;
 goto_str = ast_alloca(size);
 memset(goto_str, 0, size);
 snprintf(goto_str, size, "%s,%s,%d", ast_channel_context(chan), ast_channel_exten(chan), ast_channel_priority(chan));
 pbx_builtin_setvar_helper(chan, varname, goto_str);
 } else if (end && if_pri) {
 /* END of branch */
 snprintf(end_varname, VAR_SIZE, "END_%s", varname);
 if (! pbx_builtin_getvar_helper(chan, end_varname)) {
 char *goto_str;
 size = strlen(ast_channel_context(chan)) + strlen(ast_channel_exten(chan)) + 32;
 goto_str = ast_alloca(size);
 memset(goto_str, 0, size);
 snprintf(goto_str, size, "%s,%s,%d", ast_channel_context(chan), ast_channel_exten(chan), ast_channel_priority(chan)+1);
 pbx_builtin_setvar_helper(chan, end_varname, goto_str);
 }
 ast_parseable_goto(chan, if_pri);
 }

 return res;
}

static int if_start_exec(struct ast_channel *chan, const char *data) {
 return _if_exec(chan, data, 0);
}

static int if_end_exec(struct ast_channel *chan, const char *data) {
 return _if_exec(chan, data, 1);
}

static int if_exit_exec(struct ast_channel *chan, const char *data) {
 return _if_exec(chan, data, 2);
}

static int unload_module(void)
{
 int res;

 res = ast_unregister_application(start_app);
 res |= ast_unregister_application(stop_app);
 res |= ast_unregister_application(exit_app);

 return res;
}

static int load_module(void)
{
 int res;

 res = ast_register_application_xml(start_app, if_start_exec);
 res |= ast_register_application_xml(stop_app, if_end_exec);
 res |= ast_register_application_xml(exit_app, if_exit_exec);

 return res;
}

AST_MODULE_INFO_STANDARD_EXTENDED(ASTERISK_GPL_KEY, "If Branch and Conditional Execution");