Wed Aug 7 17:15:33 2019

Asterisk developer's documentation


app_echo.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2005, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*! \file
00020  *
00021  * \brief Echo application -- play back what you hear to evaluate latency
00022  *
00023  * \author Mark Spencer <markster@digium.com>
00024  *
00025  * \ingroup applications
00026  */
00027 
00028 /*** MODULEINFO
00029    <support_level>core</support_level>
00030  ***/
00031 
00032 #include "asterisk.h"
00033 
00034 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 360033 $")
00035 
00036 #include "asterisk/file.h"
00037 #include "asterisk/module.h"
00038 #include "asterisk/channel.h"
00039 
00040 /*** DOCUMENTATION
00041    <application name="Echo" language="en_US">
00042       <synopsis>
00043          Echo media, DTMF back to the calling party
00044       </synopsis>
00045       <syntax />
00046       <description>
00047          <para>Echos back any media or DTMF frames read from the calling 
00048          channel back to itself. This will not echo CONTROL, MODEM, or NULL
00049          frames. Note: If '#' detected application exits.</para>
00050          <para>This application does not automatically answer and should be
00051          preceeded by an application such as Answer() or Progress().</para>
00052       </description>
00053    </application>
00054  ***/
00055 
00056 static const char app[] = "Echo";
00057 
00058 static int echo_exec(struct ast_channel *chan, const char *data)
00059 {
00060    int res = -1;
00061    format_t format;
00062 
00063    format = ast_best_codec(chan->nativeformats);
00064    ast_set_write_format(chan, format);
00065    ast_set_read_format(chan, format);
00066 
00067    while (ast_waitfor(chan, -1) > -1) {
00068       struct ast_frame *f = ast_read(chan);
00069       if (!f) {
00070          break;
00071       }
00072       f->delivery.tv_sec = 0;
00073       f->delivery.tv_usec = 0;
00074       if (f->frametype != AST_FRAME_CONTROL
00075          && f->frametype != AST_FRAME_MODEM
00076          && f->frametype != AST_FRAME_NULL
00077          && ast_write(chan, f)) {
00078          ast_frfree(f);
00079          goto end;
00080       }
00081       if ((f->frametype == AST_FRAME_DTMF) && (f->subclass.integer == '#')) {
00082          res = 0;
00083          ast_frfree(f);
00084          goto end;
00085       }
00086       ast_frfree(f);
00087    }
00088 end:
00089    return res;
00090 }
00091 
00092 static int unload_module(void)
00093 {
00094    return ast_unregister_application(app);
00095 }
00096 
00097 static int load_module(void)
00098 {
00099    return ast_register_application_xml(app, echo_exec);
00100 }
00101 
00102 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Simple Echo Application");

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