func_logic.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 * Portions Copyright (C) 2005, Anthony Minessale II
 *
 * 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 Conditional logic dialplan functions
 *
 * \author Anthony Minessale II
 *
 * \ingroup functions
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

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

/*** DOCUMENTATION
   <function name="ISNULL" language="en_US">
      <synopsis>
         Check if a value is NULL.
      </synopsis>
      <syntax>
         <parameter name="data" required="true" />
      </syntax>
      <description>
         <para>Returns <literal>1</literal> if NULL or <literal>0</literal> otherwise.</para>
      </description>
   </function>
   <function name="SET" language="en_US">
      <synopsis>
         SET assigns a value to a channel variable.
      </synopsis>
      <syntax argsep="=">
         <parameter name="varname" required="true" />
         <parameter name="value" />
      </syntax>
      <description>
      </description>
   </function>
   <function name="EXISTS" language="en_US">
      <synopsis>
         Test the existence of a value.
      </synopsis>
      <syntax>
         <parameter name="data" required="true" />
      </syntax>
      <description>
         <para>Returns <literal>1</literal> if exists, <literal>0</literal> otherwise.</para>
      </description>
   </function>
   <function name="IF" language="en_US">
      <synopsis>
         Check for an expresion.
      </synopsis>
      <syntax argsep="?">
         <parameter name="expresion" required="true" />
         <parameter name="retvalue" argsep=":" required="true">
            <argument name="true" />
            <argument name="false" />
         </parameter>
      </syntax>
      <description>
         <para>Returns the data following <literal>?</literal> if true, else the data following <literal>:</literal></para>
      </description>
   </function>
   <function name="IFTIME" language="en_US">
      <synopsis>
         Temporal Conditional.
      </synopsis>
      <syntax argsep="?">
         <parameter name="timespec" required="true" />
         <parameter name="retvalue" required="true" argsep=":">
            <argument name="true" />
            <argument name="false" />
         </parameter>
      </syntax>
      <description>
         <para>Returns the data following <literal>?</literal> if true, else the data following <literal>:</literal></para>
      </description>
   </function>
   <function name="IMPORT" language="en_US">
      <synopsis>
         Retrieve the value of a variable from another channel.
      </synopsis>
      <syntax>
         <parameter name="channel" required="true" />
         <parameter name="variable" required="true" />
      </syntax>
      <description>
      </description>
   </function>
 ***/

static int isnull(struct ast_channel *chan, const char *cmd, char *data,
        char *buf, size_t len)
{
   strcpy(buf, data && *data ? "0" : "1");

   return 0;
}

static int exists(struct ast_channel *chan, const char *cmd, char *data, char *buf,
        size_t len)
{
   strcpy(buf, data && *data ? "1" : "0");

   return 0;
}

static int iftime(struct ast_channel *chan, const char *cmd, char *data, char *buf,
        size_t len)
{
   struct ast_timing timing;
   char *expr;
   char *iftrue;
   char *iffalse;

   data = ast_strip_quoted(data, "\"", "\"");
   expr = strsep(&data, "?");
   iftrue = strsep(&data, ":");
   iffalse = data;

   if (ast_strlen_zero(expr) || !(iftrue || iffalse)) {
      ast_log(LOG_WARNING,
            "Syntax IFTIME(<timespec>?[<true>][:<false>])\n");
      return -1;
   }

   if (!ast_build_timing(&timing, expr)) {
      ast_log(LOG_WARNING, "Invalid Time Spec.\n");
      ast_destroy_timing(&timing);
      return -1;
   }

   if (iftrue)
      iftrue = ast_strip_quoted(iftrue, "\"", "\"");
   if (iffalse)
      iffalse = ast_strip_quoted(iffalse, "\"", "\"");

   ast_copy_string(buf, ast_check_timing(&timing) ? S_OR(iftrue, "") : S_OR(iffalse, ""), len);
   ast_destroy_timing(&timing);

   return 0;
}

static int acf_if(struct ast_channel *chan, const char *cmd, char *data, char *buf,
        size_t len)
{
   AST_DECLARE_APP_ARGS(args1,
      AST_APP_ARG(expr);
      AST_APP_ARG(remainder);
   );
   AST_DECLARE_APP_ARGS(args2,
      AST_APP_ARG(iftrue);
      AST_APP_ARG(iffalse);
   );
   args2.iftrue = args2.iffalse = NULL; /* you have to set these, because if there is nothing after the '?',
                                 then args1.remainder will be NULL, not a pointer to a null string, and
                                 then any garbage in args2.iffalse will not be cleared, and you'll crash.
                                  -- and if you mod the ast_app_separate_args func instead, you'll really
                                 mess things up badly, because the rest of everything depends on null args
                                 for non-specified stuff. */

   AST_NONSTANDARD_APP_ARGS(args1, data, '?');
   AST_NONSTANDARD_APP_ARGS(args2, args1.remainder, ':');

   if (ast_strlen_zero(args1.expr) || !(args2.iftrue || args2.iffalse)) {
      ast_log(LOG_WARNING, "Syntax IF(<expr>?[<true>][:<false>])  (expr must be non-null, and either <true> or <false> must be non-null)\n");
      ast_log(LOG_WARNING, "      In this case, <expr>='%s', <true>='%s', and <false>='%s'\n", args1.expr, args2.iftrue, args2.iffalse);
      return -1;
   }

   args1.expr = ast_strip(args1.expr);
   if (args2.iftrue)
      args2.iftrue = ast_strip(args2.iftrue);
   if (args2.iffalse)
      args2.iffalse = ast_strip(args2.iffalse);

   ast_copy_string(buf, pbx_checkcondition(args1.expr) ? (S_OR(args2.iftrue, "")) : (S_OR(args2.iffalse, "")), len);

   return 0;
}

static int set(struct ast_channel *chan, const char *cmd, char *data, char *buf,
          size_t len)
{
   char *varname;
   char *val;

   varname = strsep(&data, "=");
   val = data;

   if (ast_strlen_zero(varname) || !val) {
      ast_log(LOG_WARNING, "Syntax SET(<varname>=[<value>])\n");
      return -1;
   }

   varname = ast_strip(varname);
   val = ast_strip(val);
   pbx_builtin_setvar_helper(chan, varname, val);
   ast_copy_string(buf, val, len);

   return 0;
}

static int set2(struct ast_channel *chan, const char *cmd, char *data, struct ast_str **str, ssize_t len)
{
   if (len > -1) {
      ast_str_make_space(str, len == 0 ? strlen(data) : len);
   }
   return set(chan, cmd, data, ast_str_buffer(*str), ast_str_size(*str));
}

static int import_helper(struct ast_channel *chan, const char *cmd, char *data, char *buf, struct ast_str **str, ssize_t len)
{
   AST_DECLARE_APP_ARGS(args,
      AST_APP_ARG(channel);
      AST_APP_ARG(varname);
   );
   AST_STANDARD_APP_ARGS(args, data);
   if (buf) {
      *buf = '\0';
   }

   if (!ast_strlen_zero(args.varname)) {
      struct ast_channel *chan2;

      if ((chan2 = ast_channel_get_by_name(args.channel))) {
         char *s = ast_alloca(strlen(args.varname) + 4);
         sprintf(s, "${%s}", args.varname);
         ast_channel_lock(chan2);
         if (buf) {
            pbx_substitute_variables_helper(chan2, s, buf, len);
         } else {
            ast_str_substitute_variables(str, len, chan2, s);
         }
         ast_channel_unlock(chan2);
         chan2 = ast_channel_unref(chan2);
      }
   }

   return 0;
}

static int import_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
{
   return import_helper(chan, cmd, data, buf, NULL, len);
}

static int import_read2(struct ast_channel *chan, const char *cmd, char *data, struct ast_str **str, ssize_t len)
{
   return import_helper(chan, cmd, data, NULL, str, len);
}

static struct ast_custom_function isnull_function = {
   .name = "ISNULL",
   .read = isnull,
   .read_max = 2,
};

static struct ast_custom_function set_function = {
   .name = "SET",
   .read = set,
   .read2 = set2,
};

static struct ast_custom_function exists_function = {
   .name = "EXISTS",
   .read = exists,
   .read_max = 2,
};

static struct ast_custom_function if_function = {
   .name = "IF",
   .read = acf_if,
};

static struct ast_custom_function if_time_function = {
   .name = "IFTIME",
   .read = iftime,
};

static struct ast_custom_function import_function = {
   .name = "IMPORT",
   .read = import_read,
   .read2 = import_read2,
};

static int unload_module(void)
{
   int res = 0;

   res |= ast_custom_function_unregister(&isnull_function);
   res |= ast_custom_function_unregister(&set_function);
   res |= ast_custom_function_unregister(&exists_function);
   res |= ast_custom_function_unregister(&if_function);
   res |= ast_custom_function_unregister(&if_time_function);
   res |= ast_custom_function_unregister(&import_function);

   return res;
}

static int load_module(void)
{
   int res = 0;

   res |= ast_custom_function_register(&isnull_function);
   res |= ast_custom_function_register(&set_function);
   res |= ast_custom_function_register(&exists_function);
   res |= ast_custom_function_register(&if_function);
   res |= ast_custom_function_register(&if_time_function);
   res |= ast_custom_function_register(&import_function);

   return res;
}

AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Logical dialplan functions");