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func_evalexten: Extension evaluation function.
This adds the EVAL_EXTEN function, which may be used to retrieve the variable-substituted data at any extension. ASTERISK-29486 Change-Id: Iad81019689674c9f4ac77d235f5d7234adbb1432
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Naveen Albert
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Friendly Automation
Friendly Automation
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147
funcs/func_evalexten.c
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147
funcs/func_evalexten.c
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/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2021, Naveen Albert
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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*
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* \brief Dialplan extension evaluation function
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*
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* \author Naveen Albert <asterisk@phreaknet.org>
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*
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* \ingroup functions
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*/
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/*** MODULEINFO
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<support_level>extended</support_level>
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***/
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#include "asterisk.h"
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#include "asterisk/module.h"
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#include "asterisk/channel.h"
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#include "asterisk/pbx.h"
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#include "asterisk/utils.h"
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#include "asterisk/app.h"
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/*** DOCUMENTATION
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<function name="EVAL_EXTEN" language="en_US">
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<synopsis>
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Evaluates the contents of a dialplan extension and returns it as a string.
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</synopsis>
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<syntax>
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<parameter name="context" />
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<parameter name="extensions" />
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<parameter name="priority" required="true" />
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</syntax>
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<description>
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<para>The EVAL_EXTEN function looks up a dialplan entry by context,extension,priority,
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evaluates the contents of a Return statement to resolve any variable or function
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references, and returns the result as a string.</para>
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<para>You can use this function to create simple user-defined lookup tables or
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user-defined functions.</para>
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<example title="Custom dialplan functions">
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[call-types]
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exten => _1NNN,1,Return(internal)
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exten => _NXXNXXXXXX,1,Return(external)
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[udf]
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exten => calleridlen,1,Return(${LEN(${CALLERID(num)})})
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[default]
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exten => _X!,1,Verbose(Call type ${EVAL_EXTEN(call-types,${EXTEN},1)} - ${EVAL_EXTEN(udf,calleridlen,1)})
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</example>
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<para>Any variables in the evaluated data will be resolved in the context of
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that extension. For example, <literal>${EXTEN}</literal> would refer to the
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EVAL_EXTEN extension, not the extension in the context invoking the function.
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This behavior is similar to other applications, e.g. <literal>Gosub</literal>.</para>
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<example title="Choosing which prompt to use">
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same => n,Read(input,${EVAL_EXTEN(prompts,${CALLERID(num)},1)})
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[prompts]
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exten => _X!,1,Return(default)
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exten => _20X,1,Return(welcome)
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exten => _2XX,1,Return(${DB(promptsettings/${EXTEN})})
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exten => _3XX,1,Return(${ODBC_MYFUNC(${EXTEN})})
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</example>
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<para>Extensions on which EVAL_EXTEN is invoked are not different from other
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extensions. However, the application at that extension is not executed.
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Only the application data is parsed and evaluated.</para>
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<para>A limitation of this function is that the application at the specified
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extension isn't actually executed, and thus unlike a Gosub, you can't pass
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arguments in the EVAL_EXTEN function.</para>
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</description>
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<see-also>
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<ref type="function">EVAL</ref>
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</see-also>
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</function>
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***/
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static int eval_exten_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
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{
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char *exten, *pri, *context, *parse;
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int ipri;
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char tmpbuf[len];
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if (ast_strlen_zero(data)) {
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ast_log(LOG_WARNING, "The EVAL_EXTEN function requires an extension\n");
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return -1;
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}
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parse = ast_strdupa(data);
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/* Split context,exten,pri */
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context = strsep(&parse, ",");
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exten = strsep(&parse, ",");
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pri = strsep(&parse, ",");
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if (pbx_parse_location(chan, &context, &exten, &pri, &ipri, NULL, NULL)) {
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return -1;
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}
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if (ast_strlen_zero(exten) || ast_strlen_zero(context)) { /* only lock if we really need to */
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ast_channel_lock(chan);
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if (ast_strlen_zero(exten)) {
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exten = ast_strdupa(ast_channel_exten(chan));
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}
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if (ast_strlen_zero(context)) {
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context = ast_strdupa(ast_channel_context(chan));
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}
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ast_channel_unlock(chan);
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}
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if (ast_get_extension_data(tmpbuf, len, chan, context, exten, ipri)) {
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return -1; /* EVAL_EXTEN failed */
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}
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pbx_substitute_variables_helper_full_location(chan, (chan) ? ast_channel_varshead(chan) : NULL, tmpbuf, buf, len, NULL, context, exten, ipri);
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return 0;
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}
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static struct ast_custom_function eval_exten_function = {
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.name = "EVAL_EXTEN",
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.read = eval_exten_read,
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};
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static int unload_module(void)
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{
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return ast_custom_function_unregister(&eval_exten_function);
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}
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static int load_module(void)
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{
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return ast_custom_function_register(&eval_exten_function);
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}
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AST_MODULE_INFO_STANDARD_EXTENDED(ASTERISK_GPL_KEY, "Extension evaluation function");
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