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- /*
- * 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");
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