func_holdintercept.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2015, Digium, Inc.
 *
 * Matt Jordan <mjordan@digium.com>
 *
 * 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 intercepts HOLD frames from channels and raises events
 *
 * \author Matt Jordan <mjordan@digium.com>
 *
 * \ingroup functions
 */
 
/*** MODULEINFO
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#include "asterisk/module.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/app.h"
#include "asterisk/frame.h"
#include "asterisk/stasis.h"
#include "asterisk/stasis_channels.h"
 
/*** DOCUMENTATION
    <function name="HOLD_INTERCEPT" language="en_US">
        <synopsis>
            Intercepts hold frames on a channel and raises an event instead of passing the frame on
        </synopsis>
        <syntax>
            <parameter name="action" required="true">
                <optionlist>
                    <option name="remove">
                        <para>W/O. Removes the hold interception function.</para>
                    </option>
                    <option name="set">
                        <para>W/O. Enable hold interception on the channel. When
                        enabled, the channel will intercept any hold action that
                        is signalled from the device, and instead simply raise an
                        event (AMI/ARI) indicating that the channel wanted to put other
                        parties on hold.</para>
                    </option>
                </optionlist>
            </parameter>
        </syntax>
    </function>
***/
 
/*! \brief Private data structure used with the function's datastore */
struct hold_intercept_data {
    int framehook_id;
};
 
/*! \brief The channel datastore the function uses to store state */
static const struct ast_datastore_info hold_intercept_datastore = {
    .type = "hold_intercept",
};
 
/*! \internal \brief Disable hold interception on the channel */
static int remove_hold_intercept(struct ast_channel *chan)
{
    struct ast_datastore *datastore = NULL;
    struct hold_intercept_data *data;
    SCOPED_CHANNELLOCK(chan_lock, chan);
 
    datastore = ast_channel_datastore_find(chan, &hold_intercept_datastore, NULL);
    if (!datastore) {
        ast_log(AST_LOG_WARNING, "Cannot remove HOLD_INTERCEPT from %s: HOLD_INTERCEPT not currently enabled\n",
                ast_channel_name(chan));
        return -1;
    }
    data = datastore->data;
 
    if (ast_framehook_detach(chan, data->framehook_id)) {
        ast_log(AST_LOG_WARNING, "Failed to remove HOLD_INTERCEPT framehook from channel %s\n",
                ast_channel_name(chan));
        return -1;
    }
 
    if (ast_channel_datastore_remove(chan, datastore)) {
        ast_log(AST_LOG_WARNING, "Failed to remove HOLD_INTERCEPT datastore from channel %s\n",
                ast_channel_name(chan));
        return -1;
    }
    ast_datastore_free(datastore);
 
    return 0;
}
 
/*! \brief Frame hook that is called to intercept hold/unhold */
static struct ast_frame *hold_intercept_framehook(struct ast_channel *chan,
    struct ast_frame *f, enum ast_framehook_event event, void *data)
{
    int frame_type;
 
    if (!f || (event != AST_FRAMEHOOK_EVENT_WRITE)) {
        return f;
    }
 
    if (f->frametype != AST_FRAME_CONTROL) {
        return f;
    }
 
    frame_type = f->subclass.integer;
    if (frame_type != AST_CONTROL_HOLD && frame_type != AST_CONTROL_UNHOLD) {
        return f;
    }
 
    /* Munch munch */
    ast_frfree(f);
    f = &ast_null_frame;
 
    ast_channel_publish_cached_blob(chan,
        frame_type == AST_CONTROL_HOLD ? ast_channel_hold_type() : ast_channel_unhold_type(),
        NULL);
 
    return f;
}
 
/*! \brief Callback function which informs upstream if we are consuming a frame of a specific type */
static int hold_intercept_framehook_consume(void *data, enum ast_frame_type type)
{
    return (type == AST_FRAME_CONTROL ? 1 : 0);
}
 
/*! \internal \brief Enable hold interception on the channel */
static int set_hold_intercept(struct ast_channel *chan)
{
    struct ast_datastore *datastore;
    struct hold_intercept_data *data;
    static struct ast_framehook_interface hold_framehook_interface = {
        .version = AST_FRAMEHOOK_INTERFACE_VERSION,
        .event_cb = hold_intercept_framehook,
        .consume_cb = hold_intercept_framehook_consume,
        .disable_inheritance = 1,
    };
    SCOPED_CHANNELLOCK(chan_lock, chan);
 
    datastore = ast_channel_datastore_find(chan, &hold_intercept_datastore, NULL);
    if (datastore) {
        ast_log(AST_LOG_WARNING, "HOLD_INTERCEPT already set on '%s'\n",
                ast_channel_name(chan));
        return 0;
    }
 
    datastore = ast_datastore_alloc(&hold_intercept_datastore, NULL);
    if (!datastore) {
        return -1;
    }
 
    data = ast_calloc(1, sizeof(*data));
    if (!data) {
        ast_datastore_free(datastore);
        return -1;
    }
 
    data->framehook_id = ast_framehook_attach(chan, &hold_framehook_interface);
    if (data->framehook_id < 0) {
        ast_log(AST_LOG_WARNING, "Failed to attach HOLD_INTERCEPT framehook to '%s'\n",
                ast_channel_name(chan));
        ast_datastore_free(datastore);
        ast_free(data);
        return -1;
    }
    datastore->data = data;
 
    ast_channel_datastore_add(chan, datastore);
 
    return 0;
}
 
/*! \internal \brief HOLD_INTERCEPT write function callback */
static int hold_intercept_fn_write(struct ast_channel *chan, const char *function,
    char *data, const char *value)
{
    int res;
 
    if (!chan) {
        return -1;
    }
 
    if (ast_strlen_zero(data)) {
        ast_log(AST_LOG_WARNING, "HOLD_INTERCEPT requires an argument\n");
        return -1;
    }
 
    if (!strcasecmp(data, "set")) {
        res = set_hold_intercept(chan);
    } else if (!strcasecmp(data, "remove")) {
        res = remove_hold_intercept(chan);
    } else {
        ast_log(AST_LOG_WARNING, "HOLD_INTERCEPT: unknown option %s\n", data);
        res = -1;
    }
 
    return res;
}
 
/*! \brief Definition of the HOLD_INTERCEPT function */
static struct ast_custom_function hold_intercept_function = {
    .name = "HOLD_INTERCEPT",
    .write = hold_intercept_fn_write,
};
 
/*! \internal \brief Unload the module */
static int unload_module(void)
{
    return ast_custom_function_unregister(&hold_intercept_function);
}
 
/*! \internal \brief Load the module */
static int load_module(void)
{
    return ast_custom_function_register(&hold_intercept_function) ? AST_MODULE_LOAD_DECLINE : AST_MODULE_LOAD_SUCCESS;
}
 
AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Hold interception dialplan function");