asterisk/funcs/func_frame_drop.c

303 lines
8.5 KiB
C

/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2021, Naveen Albert
*
* Naveen Albert <asterisk@phreaknet.org>
*
* 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 Function that drops specified frames from channels
*
* \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/framehook.h"
/*** DOCUMENTATION
<function name="FRAME_DROP" language="en_US">
<since>
<version>16.21.0</version>
<version>18.7.0</version>
<version>19.0.0</version>
</since>
<synopsis>
Drops specific frame types in the TX or RX direction on a channel.
</synopsis>
<syntax>
<parameter name="direction" required="true">
<para>List of frame types to be dropped for the specified direction. Direction can be <literal>TX</literal> or <literal>RX</literal>. The <literal>TX</literal> direction will prevent Asterisk from sending frames to a channel, and the <literal>RX</literal> direction will prevent Asterisk from receiving frames from a channel.</para>
<para>Subsequent calls to this function will replace previous settings, allowing certain frames to be dropped only temporarily, for instance.</para>
<para>Below are the different types of frames that can be dropped. Other actions may need to be taken in conjunction with use of this function:
for instance, if you drop ANSWER control frames, you should explicitly use <literal>Progress()</literal> for your call or undesired behavior
may occur.</para>
<enumlist>
<enum name = "DTMF_BEGIN" />
<enum name = "DTMF_END" />
<enum name = "VOICE" />
<enum name = "VIDEO" />
<enum name = "CONTROL" />
<enum name = "NULL" />
<enum name = "IAX" />
<enum name = "TEXT" />
<enum name = "TEXT_DATA" />
<enum name = "IMAGE" />
<enum name = "HTML" />
<enum name = "CNG" />
<enum name = "MODEM" />
</enumlist>
<para>The following CONTROL frames can also be dropped:</para>
<enumlist>
<enum name = "RING" />
<enum name = "RINGING" />
<enum name = "ANSWER" />
<enum name = "BUSY" />
<enum name = "TAKEOFFHOOK" />
<enum name = "OFFHOOK" />
<enum name = "CONGESTION" />
<enum name = "FLASH" />
<enum name = "WINK" />
<enum name = "PROGRESS" />
<enum name = "PROCEEDING" />
<enum name = "HOLD" />
<enum name = "UNHOLD" />
<enum name = "VIDUPDATE" />
<enum name = "CONNECTED_LINE" />
<enum name = "REDIRECTING" />
</enumlist>
</parameter>
</syntax>
<description>
<para>Examples:</para>
<example title="Drop only DTMF frames towards this channel">
exten => 1,1,Set(FRAME_DROP(TX)=DTMF_BEGIN,DTMF_END)
</example>
<example title="Drop only Answer control frames towards this channel">
exten => 1,1,Set(FRAME_DROP(TX)=ANSWER)
</example>
<example title="Drop only DTMF frames received on this channel">
exten => 1,1,Set(FRAME_DROP(RX)=DTMF_BEGIN,DTMF_END)
</example>
</description>
</function>
***/
static struct {
enum ast_frame_type type;
const char *str;
} frametype2str[] = {
{ AST_FRAME_DTMF_BEGIN, ",DTMF_BEGIN," },
{ AST_FRAME_DTMF_END, ",DTMF_END," },
{ AST_FRAME_VOICE, ",VOICE," },
{ AST_FRAME_VIDEO, ",VIDEO," },
{ AST_FRAME_CONTROL, ",CONTROL," },
{ AST_FRAME_NULL, ",NULL," },
{ AST_FRAME_IAX, ",IAX," },
{ AST_FRAME_TEXT, ",TEXT," },
{ AST_FRAME_TEXT_DATA, ",TEXT_DATA," },
{ AST_FRAME_IMAGE, ",IMAGE," },
{ AST_FRAME_HTML, ",HTML," },
{ AST_FRAME_CNG, ",CNG," },
{ AST_FRAME_MODEM, ",MODEM," },
};
static struct {
int type;
const char *str;
} controlframetype2str[] = {
{ AST_CONTROL_RING, ",RING," },
{ AST_CONTROL_RINGING, ",RINGING," },
{ AST_CONTROL_ANSWER, ",ANSWER," },
{ AST_CONTROL_BUSY, ",BUSY," },
{ AST_CONTROL_TAKEOFFHOOK, ",TAKEOFFHOOK," },
{ AST_CONTROL_OFFHOOK, ",OFFHOOK," },
{ AST_CONTROL_CONGESTION, ",CONGESTION," },
{ AST_CONTROL_FLASH, ",FLASH," },
{ AST_CONTROL_WINK, ",WINK," },
{ AST_CONTROL_PROGRESS, ",PROGRESS," },
{ AST_CONTROL_PROCEEDING, ",PROCEEDING," },
{ AST_CONTROL_HOLD, ",HOLD," },
{ AST_CONTROL_UNHOLD, ",UNHOLD," },
{ AST_CONTROL_VIDUPDATE, ",VIDUPDATE," },
{ AST_CONTROL_CONNECTED_LINE, ",CONNECTED_LINE," },
{ AST_CONTROL_REDIRECTING, ",REDIRECTING," },
};
enum direction {
TX = 0,
RX,
};
struct frame_drop_data {
enum direction list_type;
int values[ARRAY_LEN(frametype2str)];
int controlvalues[ARRAY_LEN(controlframetype2str)];
};
static void datastore_destroy_cb(void *data) {
ast_free(data);
}
static const struct ast_datastore_info frame_drop_datastore = {
.type = "framedrop",
.destroy = datastore_destroy_cb
};
static void hook_destroy_cb(void *framedata)
{
ast_free(framedata);
}
static struct ast_frame *hook_event_cb(struct ast_channel *chan, struct ast_frame *frame, enum ast_framehook_event event, void *data)
{
int i;
int drop_frame = 0;
struct frame_drop_data *framedata = data;
if (!frame) {
return frame;
}
if (!((event == AST_FRAMEHOOK_EVENT_WRITE && framedata->list_type == TX) ||
(event == AST_FRAMEHOOK_EVENT_READ && framedata->list_type == RX))) {
return frame;
}
if (frame->frametype == AST_FRAME_CONTROL) {
for (i = 0; i < ARRAY_LEN(controlframetype2str); i++) {
if (frame->subclass.integer == controlframetype2str[i].type) {
if (framedata->controlvalues[i]) {
drop_frame = 1;
}
break;
}
}
} else {
for (i = 0; i < ARRAY_LEN(frametype2str); i++) {
if (frame->frametype == frametype2str[i].type) {
if (framedata->values[i]) {
drop_frame = 1;
}
break;
}
}
}
if (drop_frame) {
ast_frfree(frame);
frame = &ast_null_frame;
}
return frame;
}
static int frame_drop_helper(struct ast_channel *chan, const char *cmd, char *data, const char *value)
{
char *buffer;
struct frame_drop_data *framedata;
struct ast_datastore *datastore = NULL;
struct ast_framehook_interface interface = {
.version = AST_FRAMEHOOK_INTERFACE_VERSION,
.event_cb = hook_event_cb,
.destroy_cb = hook_destroy_cb,
};
int i = 0;
if (!(framedata = ast_calloc(1, sizeof(*framedata)))) {
return 0;
}
interface.data = framedata;
if (!strcasecmp(data, "RX")) {
framedata->list_type = RX;
} else {
framedata->list_type = TX;
}
buffer = ast_malloc(sizeof(value) + 3); /* leading and trailing comma and null terminator */
snprintf(buffer, sizeof(value) + 2, ",%s,", value);
for (i = 0; i < ARRAY_LEN(frametype2str); i++) {
if (strcasestr(buffer, frametype2str[i].str)) {
framedata->values[i] = 1;
}
}
for (i = 0; i < ARRAY_LEN(controlframetype2str); i++) {
if (strcasestr(buffer, controlframetype2str[i].str)) {
framedata->controlvalues[i] = 1;
}
}
ast_free(buffer);
ast_channel_lock(chan);
i = ast_framehook_attach(chan, &interface);
if (i >= 0) {
int *id;
if ((datastore = ast_channel_datastore_find(chan, &frame_drop_datastore, NULL))) {
id = datastore->data;
ast_framehook_detach(chan, *id);
ast_channel_datastore_remove(chan, datastore);
ast_datastore_free(datastore);
}
if (!(datastore = ast_datastore_alloc(&frame_drop_datastore, NULL))) {
ast_framehook_detach(chan, i);
ast_channel_unlock(chan);
return 0;
}
if (!(id = ast_calloc(1, sizeof(int)))) {
ast_datastore_free(datastore);
ast_framehook_detach(chan, i);
ast_channel_unlock(chan);
return 0;
}
*id = i; /* Store off the id. The channel is still locked so it is safe to access this ptr. */
datastore->data = id;
ast_channel_datastore_add(chan, datastore);
}
ast_channel_unlock(chan);
return 0;
}
static struct ast_custom_function frame_drop_function = {
.name = "FRAME_DROP",
.write = frame_drop_helper,
};
static int unload_module(void)
{
return ast_custom_function_unregister(&frame_drop_function);
}
static int load_module(void)
{
int res = ast_custom_function_register(&frame_drop_function);
return res ? AST_MODULE_LOAD_DECLINE : AST_MODULE_LOAD_SUCCESS;
}
AST_MODULE_INFO_STANDARD_EXTENDED(ASTERISK_GPL_KEY, "Function to drop frames on a channel.");