asterisk/funcs/func_evalexten.c

148 lines
4.5 KiB
C

/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2021, Naveen Albert
*
* 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 Dialplan extension evaluation function
*
* \author Naveen Albert <asterisk@phreaknet.org>
*
* \ingroup functions
*/
/*** MODULEINFO
<support_level>extended</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="EVAL_EXTEN" language="en_US">
<synopsis>
Evaluates the contents of a dialplan extension and returns it as a string.
</synopsis>
<syntax>
<parameter name="context" />
<parameter name="extensions" />
<parameter name="priority" required="true" />
</syntax>
<description>
<para>The EVAL_EXTEN function looks up a dialplan entry by context,extension,priority,
evaluates the contents of a Return statement to resolve any variable or function
references, and returns the result as a string.</para>
<para>You can use this function to create simple user-defined lookup tables or
user-defined functions.</para>
<example title="Custom dialplan functions">
[call-types]
exten => _1NNN,1,Return(internal)
exten => _NXXNXXXXXX,1,Return(external)
[udf]
exten => calleridlen,1,Return(${LEN(${CALLERID(num)})})
[default]
exten => _X!,1,Verbose(Call type ${EVAL_EXTEN(call-types,${EXTEN},1)} - ${EVAL_EXTEN(udf,calleridlen,1)})
</example>
<para>Any variables in the evaluated data will be resolved in the context of
that extension. For example, <literal>${EXTEN}</literal> would refer to the
EVAL_EXTEN extension, not the extension in the context invoking the function.
This behavior is similar to other applications, e.g. <literal>Gosub</literal>.</para>
<example title="Choosing which prompt to use">
same => n,Read(input,${EVAL_EXTEN(prompts,${CALLERID(num)},1)})
[prompts]
exten => _X!,1,Return(default)
exten => _20X,1,Return(welcome)
exten => _2XX,1,Return(${DB(promptsettings/${EXTEN})})
exten => _3XX,1,Return(${ODBC_MYFUNC(${EXTEN})})
</example>
<para>Extensions on which EVAL_EXTEN is invoked are not different from other
extensions. However, the application at that extension is not executed.
Only the application data is parsed and evaluated.</para>
<para>A limitation of this function is that the application at the specified
extension isn't actually executed, and thus unlike a Gosub, you can't pass
arguments in the EVAL_EXTEN function.</para>
</description>
<see-also>
<ref type="function">EVAL</ref>
</see-also>
</function>
***/
static int eval_exten_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
{
char *exten, *pri, *context, *parse;
int ipri;
char tmpbuf[len];
if (ast_strlen_zero(data)) {
ast_log(LOG_WARNING, "The EVAL_EXTEN function requires an extension\n");
return -1;
}
parse = ast_strdupa(data);
/* Split context,exten,pri */
context = strsep(&parse, ",");
exten = strsep(&parse, ",");
pri = strsep(&parse, ",");
if (pbx_parse_location(chan, &context, &exten, &pri, &ipri, NULL, NULL)) {
return -1;
}
if (ast_strlen_zero(exten) || ast_strlen_zero(context)) { /* only lock if we really need to */
ast_channel_lock(chan);
if (ast_strlen_zero(exten)) {
exten = ast_strdupa(ast_channel_exten(chan));
}
if (ast_strlen_zero(context)) {
context = ast_strdupa(ast_channel_context(chan));
}
ast_channel_unlock(chan);
}
if (ast_get_extension_data(tmpbuf, len, chan, context, exten, ipri)) {
return -1; /* EVAL_EXTEN failed */
}
pbx_substitute_variables_helper_full_location(chan, (chan) ? ast_channel_varshead(chan) : NULL, tmpbuf, buf, len, NULL, context, exten, ipri);
return 0;
}
static struct ast_custom_function eval_exten_function = {
.name = "EVAL_EXTEN",
.read = eval_exten_read,
};
static int unload_module(void)
{
return ast_custom_function_unregister(&eval_exten_function);
}
static int load_module(void)
{
return ast_custom_function_register(&eval_exten_function);
}
AST_MODULE_INFO_STANDARD_EXTENDED(ASTERISK_GPL_KEY, "Extension evaluation function");