Thu Apr 28 2011 17:13:33

Asterisk developer's documentation


func_logic.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2006, Digium, Inc.
00005  * Portions Copyright (C) 2005, Anthony Minessale II
00006  *
00007  * See http://www.asterisk.org for more information about
00008  * the Asterisk project. Please do not directly contact
00009  * any of the maintainers of this project for assistance;
00010  * the project provides a web site, mailing lists and IRC
00011  * channels for your use.
00012  *
00013  * This program is free software, distributed under the terms of
00014  * the GNU General Public License Version 2. See the LICENSE file
00015  * at the top of the source tree.
00016  */
00017 
00018 /*! \file
00019  * 
00020  * \brief Conditional logic dialplan functions
00021  * 
00022  * \author Anthony Minessale II
00023  *
00024  * \ingroup functions
00025  */
00026 
00027 #include "asterisk.h"
00028 
00029 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 168547 $")
00030 
00031 #include "asterisk/module.h"
00032 #include "asterisk/channel.h"
00033 #include "asterisk/pbx.h"
00034 #include "asterisk/utils.h"
00035 #include "asterisk/app.h"
00036 
00037 /*** DOCUMENTATION
00038    <function name="ISNULL" language="en_US">
00039       <synopsis>
00040          Check if a value is NULL.
00041       </synopsis>
00042       <syntax>
00043          <parameter name="data" required="true" />
00044       </syntax>
00045       <description>
00046          <para>Returns <literal>1</literal> if NULL or <literal>0</literal> otherwise.</para>
00047       </description>
00048    </function>
00049    <function name="SET" language="en_US">
00050       <synopsis>
00051          SET assigns a value to a channel variable.
00052       </synopsis>
00053       <syntax argsep="=">
00054          <parameter name="varname" required="true" />
00055          <parameter name="value" />
00056       </syntax>
00057       <description>
00058       </description>
00059    </function>
00060    <function name="EXISTS" language="en_US">
00061       <synopsis>
00062          Test the existence of a value.
00063       </synopsis>
00064       <syntax>
00065          <parameter name="data" required="true" />
00066       </syntax>
00067       <description>
00068          <para>Returns <literal>1</literal> if exists, <literal>0</literal> otherwise.</para>
00069       </description>
00070    </function>
00071    <function name="IF" language="en_US">
00072       <synopsis>
00073          Check for an expresion.
00074       </synopsis>
00075       <syntax argsep="?">
00076          <parameter name="expresion" required="true" />
00077          <parameter name="retvalue" argsep=":" required="true">
00078             <argument name="true" />
00079             <argument name="false" />
00080          </parameter>
00081       </syntax>
00082       <description>
00083          <para>Returns the data following <literal>?</literal> if true, else the data following <literal>:</literal></para>
00084       </description> 
00085    </function>
00086    <function name="IFTIME" language="en_US">
00087       <synopsis>
00088          Temporal Conditional.
00089       </synopsis>
00090       <syntax argsep="?">
00091          <parameter name="timespec" required="true" />
00092          <parameter name="retvalue" required="true" argsep=":">
00093             <argument name="true" />
00094             <argument name="false" />
00095          </parameter>
00096       </syntax>
00097       <description>
00098          <para>Returns the data following <literal>?</literal> if true, else the data following <literal>:</literal></para>
00099       </description>
00100    </function>
00101    <function name="IMPORT" language="en_US">
00102       <synopsis>
00103          Retrieve the value of a variable from another channel.
00104       </synopsis>
00105       <syntax>
00106          <parameter name="channel" required="true" />
00107          <parameter name="variable" required="true" />
00108       </syntax>
00109       <description>
00110       </description>
00111    </function>
00112  ***/
00113 
00114 static int isnull(struct ast_channel *chan, const char *cmd, char *data,
00115         char *buf, size_t len)
00116 {
00117    strcpy(buf, data && *data ? "0" : "1");
00118 
00119    return 0;
00120 }
00121 
00122 static int exists(struct ast_channel *chan, const char *cmd, char *data, char *buf,
00123         size_t len)
00124 {
00125    strcpy(buf, data && *data ? "1" : "0");
00126 
00127    return 0;
00128 }
00129 
00130 static int iftime(struct ast_channel *chan, const char *cmd, char *data, char *buf,
00131         size_t len)
00132 {
00133    struct ast_timing timing;
00134    char *expr;
00135    char *iftrue;
00136    char *iffalse;
00137 
00138    data = ast_strip_quoted(data, "\"", "\"");
00139    expr = strsep(&data, "?");
00140    iftrue = strsep(&data, ":");
00141    iffalse = data;
00142 
00143    if (ast_strlen_zero(expr) || !(iftrue || iffalse)) {
00144       ast_log(LOG_WARNING,
00145             "Syntax IFTIME(<timespec>?[<true>][:<false>])\n");
00146       return -1;
00147    }
00148 
00149    if (!ast_build_timing(&timing, expr)) {
00150       ast_log(LOG_WARNING, "Invalid Time Spec.\n");
00151       ast_destroy_timing(&timing);
00152       return -1;
00153    }
00154 
00155    if (iftrue)
00156       iftrue = ast_strip_quoted(iftrue, "\"", "\"");
00157    if (iffalse)
00158       iffalse = ast_strip_quoted(iffalse, "\"", "\"");
00159 
00160    ast_copy_string(buf, ast_check_timing(&timing) ? S_OR(iftrue, "") : S_OR(iffalse, ""), len);
00161    ast_destroy_timing(&timing);
00162 
00163    return 0;
00164 }
00165 
00166 static int acf_if(struct ast_channel *chan, const char *cmd, char *data, char *buf,
00167         size_t len)
00168 {
00169    AST_DECLARE_APP_ARGS(args1,
00170       AST_APP_ARG(expr);
00171       AST_APP_ARG(remainder);
00172    );
00173    AST_DECLARE_APP_ARGS(args2,
00174       AST_APP_ARG(iftrue);
00175       AST_APP_ARG(iffalse);
00176    );
00177    args2.iftrue = args2.iffalse = NULL; /* you have to set these, because if there is nothing after the '?',
00178                                  then args1.remainder will be NULL, not a pointer to a null string, and
00179                                  then any garbage in args2.iffalse will not be cleared, and you'll crash.
00180                                   -- and if you mod the ast_app_separate_args func instead, you'll really
00181                                  mess things up badly, because the rest of everything depends on null args
00182                                  for non-specified stuff. */
00183    
00184    AST_NONSTANDARD_APP_ARGS(args1, data, '?');
00185    AST_NONSTANDARD_APP_ARGS(args2, args1.remainder, ':');
00186 
00187    if (ast_strlen_zero(args1.expr) || !(args2.iftrue || args2.iffalse)) {
00188       ast_log(LOG_WARNING, "Syntax IF(<expr>?[<true>][:<false>])  (expr must be non-null, and either <true> or <false> must be non-null)\n");
00189       ast_log(LOG_WARNING, "      In this case, <expr>='%s', <true>='%s', and <false>='%s'\n", args1.expr, args2.iftrue, args2.iffalse);
00190       return -1;
00191    }
00192 
00193    args1.expr = ast_strip(args1.expr);
00194    if (args2.iftrue)
00195       args2.iftrue = ast_strip(args2.iftrue);
00196    if (args2.iffalse)
00197       args2.iffalse = ast_strip(args2.iffalse);
00198 
00199    ast_copy_string(buf, pbx_checkcondition(args1.expr) ? (S_OR(args2.iftrue, "")) : (S_OR(args2.iffalse, "")), len);
00200 
00201    return 0;
00202 }
00203 
00204 static int set(struct ast_channel *chan, const char *cmd, char *data, char *buf,
00205           size_t len)
00206 {
00207    char *varname;
00208    char *val;
00209 
00210    varname = strsep(&data, "=");
00211    val = data;
00212 
00213    if (ast_strlen_zero(varname) || !val) {
00214       ast_log(LOG_WARNING, "Syntax SET(<varname>=[<value>])\n");
00215       return -1;
00216    }
00217 
00218    varname = ast_strip(varname);
00219    val = ast_strip(val);
00220    pbx_builtin_setvar_helper(chan, varname, val);
00221    ast_copy_string(buf, val, len);
00222 
00223    return 0;
00224 }
00225 
00226 static int acf_import(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
00227 {
00228    AST_DECLARE_APP_ARGS(args,
00229       AST_APP_ARG(channel);
00230       AST_APP_ARG(varname);
00231    );
00232    AST_STANDARD_APP_ARGS(args, data);
00233    buf[0] = 0;
00234    if (!ast_strlen_zero(args.varname)) {
00235       struct ast_channel *chan2 = ast_get_channel_by_name_locked(args.channel);
00236       if (chan2) {
00237          char *s = alloca(strlen(args.varname) + 4);
00238          if (s) {
00239             sprintf(s, "${%s}", args.varname);
00240             pbx_substitute_variables_helper(chan2, s, buf, len);
00241          }
00242          ast_channel_unlock(chan2);
00243       }
00244    }
00245    return 0;
00246 }
00247 
00248 static struct ast_custom_function isnull_function = {
00249    .name = "ISNULL",
00250    .read = isnull,
00251 };
00252 
00253 static struct ast_custom_function set_function = {
00254    .name = "SET",
00255    .read = set,
00256 };
00257 
00258 static struct ast_custom_function exists_function = {
00259    .name = "EXISTS",
00260    .read = exists,
00261 };
00262 
00263 static struct ast_custom_function if_function = {
00264    .name = "IF",
00265    .read = acf_if,
00266 };
00267 
00268 static struct ast_custom_function if_time_function = {
00269    .name = "IFTIME",
00270    .read = iftime,
00271 };
00272 
00273 static struct ast_custom_function import_function = {
00274    .name = "IMPORT",
00275    .read = acf_import,
00276 };
00277 
00278 static int unload_module(void)
00279 {
00280    int res = 0;
00281 
00282    res |= ast_custom_function_unregister(&isnull_function);
00283    res |= ast_custom_function_unregister(&set_function);
00284    res |= ast_custom_function_unregister(&exists_function);
00285    res |= ast_custom_function_unregister(&if_function);
00286    res |= ast_custom_function_unregister(&if_time_function);
00287    res |= ast_custom_function_unregister(&import_function);
00288 
00289    return res;
00290 }
00291 
00292 static int load_module(void)
00293 {
00294    int res = 0;
00295 
00296    res |= ast_custom_function_register(&isnull_function);
00297    res |= ast_custom_function_register(&set_function);
00298    res |= ast_custom_function_register(&exists_function);
00299    res |= ast_custom_function_register(&if_function);
00300    res |= ast_custom_function_register(&if_time_function);
00301    res |= ast_custom_function_register(&import_function);
00302 
00303    return res;
00304 }
00305 
00306 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Logical dialplan functions");