func_frame_drop: New function
Adds function to selectively drop specified frames in the TX or RX direction on a channel, including control frames. ASTERISK-29478 Change-Id: I8147c9d55d74e2e48861edba6b22f930920541ec
This commit is contained in:
Naveen Albert
Friendly Automation
parent
835ab50724
commit
7383f74dfc
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Subject: func_framedrop
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New function to selectively drop specified frames
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in either direction on a channel.
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@ -0,0 +1,291 @@
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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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* Naveen Albert <asterisk@phreaknet.org>
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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 Function that drops specified frames from channels
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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/framehook.h"
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/*** DOCUMENTATION
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<function name="FRAME_DROP" language="en_US">
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<synopsis>
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Drops specific frame types in the TX or RX direction on a channel.
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</synopsis>
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<syntax>
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<parameter name="direction" required="true">
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<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>
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<para>Subsequent calls to this function will replace previous settings, allowing certain frames to be dropped only temporarily, for instance.</para>
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<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:
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for instance, if you drop ANSWER control frames, you should explicitly use <literal>Progress()</literal> for your call or undesired behavior
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may occur.</para>
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<enumlist>
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<enum name = "DTMF_BEGIN" />
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<enum name = "DTMF_END" />
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<enum name = "VOICE" />
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<enum name = "VIDEO" />
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<enum name = "CONTROL" />
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<enum name = "NULL" />
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<enum name = "IAX" />
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<enum name = "TEXT" />
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<enum name = "TEXT_DATA" />
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<enum name = "IMAGE" />
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<enum name = "HTML" />
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<enum name = "CNG" />
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<enum name = "MODEM" />
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</enumlist>
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<para>The following CONTROL frames can also be dropped:</para>
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<enumlist>
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<enum name = "RING" />
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<enum name = "RINGING" />
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<enum name = "ANSWER" />
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<enum name = "BUSY" />
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<enum name = "TAKEOFFHOOK" />
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<enum name = "OFFHOOK" />
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<enum name = "CONGESTION" />
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<enum name = "FLASH" />
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<enum name = "WINK" />
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<enum name = "PROGRESS" />
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<enum name = "PROCEEDING" />
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<enum name = "HOLD" />
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<enum name = "UNHOLD" />
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<enum name = "VIDUPDATE" />
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<enum name = "CONNECTED_LINE" />
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<enum name = "REDIRECTING" />
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</enumlist>
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</parameter>
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</syntax>
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<description>
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<para>Examples:</para>
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<para>exten => 1,1,Set(FRAME_DROP(TX)=DTMF_BEGIN,DTMF_END); drop only DTMF frames towards this channel.</para>
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<para>exten => 1,1,Set(FRAME_DROP(TX)=ANSWER); drop only ANSWER CONTROL frames towards this channel.</para>
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<para>exten => 1,1,Set(FRAME_DROP(RX)=DTMF_BEGIN,DTMF_END); drop only DTMF frames received on this channel.</para>
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</description>
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</function>
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***/
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static struct {
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enum ast_frame_type type;
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const char *str;
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} frametype2str[] = {
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{ AST_FRAME_DTMF_BEGIN, ",DTMF_BEGIN," },
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{ AST_FRAME_DTMF_END, ",DTMF_END," },
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{ AST_FRAME_VOICE, ",VOICE," },
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{ AST_FRAME_VIDEO, ",VIDEO," },
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{ AST_FRAME_CONTROL, ",CONTROL," },
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{ AST_FRAME_NULL, ",NULL," },
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{ AST_FRAME_IAX, ",IAX," },
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{ AST_FRAME_TEXT, ",TEXT," },
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{ AST_FRAME_TEXT_DATA, ",TEXT_DATA," },
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{ AST_FRAME_IMAGE, ",IMAGE," },
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{ AST_FRAME_HTML, ",HTML," },
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{ AST_FRAME_CNG, ",CNG," },
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{ AST_FRAME_MODEM, ",MODEM," },
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};
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static struct {
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int type;
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const char *str;
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} controlframetype2str[] = {
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{ AST_CONTROL_RING, ",RING," },
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{ AST_CONTROL_RINGING, ",RINGING," },
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{ AST_CONTROL_ANSWER, ",ANSWER," },
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{ AST_CONTROL_BUSY, ",BUSY," },
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{ AST_CONTROL_TAKEOFFHOOK, ",TAKEOFFHOOK," },
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{ AST_CONTROL_OFFHOOK, ",OFFHOOK," },
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{ AST_CONTROL_CONGESTION, ",CONGESTION," },
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{ AST_CONTROL_FLASH, ",FLASH," },
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{ AST_CONTROL_WINK, ",WINK," },
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{ AST_CONTROL_PROGRESS, ",PROGRESS," },
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{ AST_CONTROL_PROCEEDING, ",PROCEEDING," },
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{ AST_CONTROL_HOLD, ",HOLD," },
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{ AST_CONTROL_UNHOLD, ",UNHOLD," },
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{ AST_CONTROL_VIDUPDATE, ",VIDUPDATE," },
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{ AST_CONTROL_CONNECTED_LINE, ",CONNECTED_LINE," },
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{ AST_CONTROL_REDIRECTING, ",REDIRECTING," },
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};
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enum direction {
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TX = 0,
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RX,
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};
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struct frame_drop_data {
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enum direction list_type;
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int values[ARRAY_LEN(frametype2str)];
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int controlvalues[ARRAY_LEN(controlframetype2str)];
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};
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static void datastore_destroy_cb(void *data) {
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ast_free(data);
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}
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static const struct ast_datastore_info frame_drop_datastore = {
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.type = "framedrop",
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.destroy = datastore_destroy_cb
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};
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static void hook_destroy_cb(void *framedata)
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{
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ast_free(framedata);
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}
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static struct ast_frame *hook_event_cb(struct ast_channel *chan, struct ast_frame *frame, enum ast_framehook_event event, void *data)
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{
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int i;
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int drop_frame = 0;
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struct frame_drop_data *framedata = data;
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if (!frame) {
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return frame;
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}
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if (!((event == AST_FRAMEHOOK_EVENT_WRITE && framedata->list_type == TX) ||
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(event == AST_FRAMEHOOK_EVENT_READ && framedata->list_type == RX))) {
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return frame;
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}
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if (frame->frametype == AST_FRAME_CONTROL) {
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for (i = 0; i < ARRAY_LEN(controlframetype2str); i++) {
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if (frame->subclass.integer == controlframetype2str[i].type) {
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if (framedata->controlvalues[i]) {
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drop_frame = 1;
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}
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break;
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}
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}
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} else {
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for (i = 0; i < ARRAY_LEN(frametype2str); i++) {
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if (frame->frametype == frametype2str[i].type) {
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if (framedata->values[i]) {
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drop_frame = 1;
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}
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break;
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}
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}
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}
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if (drop_frame) {
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ast_frfree(frame);
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frame = &ast_null_frame;
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}
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return frame;
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}
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static int frame_drop_helper(struct ast_channel *chan, const char *cmd, char *data, const char *value)
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{
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char *buffer;
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struct frame_drop_data *framedata;
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struct ast_datastore *datastore = NULL;
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struct ast_framehook_interface interface = {
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.version = AST_FRAMEHOOK_INTERFACE_VERSION,
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.event_cb = hook_event_cb,
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.destroy_cb = hook_destroy_cb,
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};
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int i = 0;
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if (!(framedata = ast_calloc(1, sizeof(*framedata)))) {
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return 0;
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}
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interface.data = framedata;
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if (!strcasecmp(data, "RX")) {
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framedata->list_type = RX;
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} else {
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framedata->list_type = TX;
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}
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buffer = ast_malloc(sizeof(value) + 3); /* leading and trailing comma and null terminator */
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snprintf(buffer, sizeof(value) + 2, ",%s,", value);
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for (i = 0; i < ARRAY_LEN(frametype2str); i++) {
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if (strcasestr(value, frametype2str[i].str)) {
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framedata->values[i] = 1;
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}
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}
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for (i = 0; i < ARRAY_LEN(controlframetype2str); i++) {
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if (strcasestr(value, controlframetype2str[i].str)) {
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framedata->controlvalues[i] = 1;
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}
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}
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ast_free(buffer);
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ast_channel_lock(chan);
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i = ast_framehook_attach(chan, &interface);
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if (i >= 0) {
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int *id;
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if ((datastore = ast_channel_datastore_find(chan, &frame_drop_datastore, NULL))) {
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id = datastore->data;
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ast_framehook_detach(chan, *id);
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ast_channel_datastore_remove(chan, datastore);
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ast_datastore_free(datastore);
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}
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if (!(datastore = ast_datastore_alloc(&frame_drop_datastore, NULL))) {
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ast_framehook_detach(chan, i);
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ast_channel_unlock(chan);
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return 0;
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}
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if (!(id = ast_calloc(1, sizeof(int)))) {
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ast_datastore_free(datastore);
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ast_framehook_detach(chan, i);
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ast_channel_unlock(chan);
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return 0;
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}
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*id = i; /* Store off the id. The channel is still locked so it is safe to access this ptr. */
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datastore->data = id;
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ast_channel_datastore_add(chan, datastore);
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}
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ast_channel_unlock(chan);
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return 0;
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}
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static struct ast_custom_function frame_drop_function = {
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.name = "FRAME_DROP",
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.write = frame_drop_helper,
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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(&frame_drop_function);
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}
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static int load_module(void)
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{
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int res = ast_custom_function_register(&frame_drop_function);
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return res ? AST_MODULE_LOAD_DECLINE : AST_MODULE_LOAD_SUCCESS;
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}
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AST_MODULE_INFO_STANDARD_EXTENDED(ASTERISK_GPL_KEY, "Function to drop frames on a channel.");
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