transport.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2021, Sangoma Technologies Corporation
 *
 * Kevin Harwell <kharwell@sangoma.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.
 */
 
#include "asterisk.h"
 
#include "asterisk/utils.h"
 
#include "logger.h"
#include "transport.h"
#include "transport_websocket.h"
 
struct aeap_transport *aeap_transport_create(const char *type)
{
    struct aeap_transport *transport = NULL;
 
    if (!strncasecmp(type, "ws", 2)) {
        transport = (struct aeap_transport *)aeap_transport_websocket_create();
    }
 
    if (!transport) {
        ast_log(LOG_ERROR, "AEAP transport: failed to create for type '%s'\n", type);
        return NULL;
    }
 
    ast_mutex_init(&transport->read_lock);
    ast_mutex_init(&transport->write_lock);
 
    transport->connected = 0;
 
    return transport;
}
 
int aeap_transport_connect(struct aeap_transport *transport, const char *url,
    const char *protocol, int timeout)
{
    int res;
 
    SCOPED_MUTEX(rlock, &transport->read_lock);
    SCOPED_MUTEX(wlock, &transport->write_lock);
 
    if (aeap_transport_is_connected(transport)) {
        return 0;
    }
 
    res = transport->vtable->connect(transport, url, protocol, timeout);
    if (!res) {
        transport->connected = 1;
    }
 
    return res;
}
 
struct aeap_transport *aeap_transport_create_and_connect(const char *type,
    const char *url, const char *protocol, int timeout)
{
    struct aeap_transport *transport = aeap_transport_create(type);
 
    if (!transport) {
        return NULL;
    }
 
    if (aeap_transport_connect(transport, url, protocol, timeout)) {
        aeap_transport_destroy(transport);
        return NULL;
    }
 
    return transport;
}
 
int aeap_transport_is_connected(struct aeap_transport *transport)
{
    /*
     * Avoid using a lock to 'read' the 'connected' variable in order to
     * keep things slightly more efficient.
     */
    return ast_atomic_fetch_add(&transport->connected, 0, __ATOMIC_RELAXED);
}
 
int aeap_transport_disconnect(struct aeap_transport *transport)
{
    int res;
 
    SCOPED_MUTEX(rlock, &transport->read_lock);
    SCOPED_MUTEX(wlock, &transport->write_lock);
 
    if (!aeap_transport_is_connected(transport)) {
        return 0;
    }
 
    res = transport->vtable->disconnect(transport);
 
    /*
     * Even though the transport is locked here use atomics to set the value of
     * 'connected' since it's possible the variable is being 'read' by another
     * thread via the 'is_connected' call.
     */
    ast_atomic_fetch_sub(&transport->connected, 1, __ATOMIC_RELAXED);
 
    return res;
}
 
void aeap_transport_destroy(struct aeap_transport *transport)
{
    if (!transport) {
        return;
    }
 
    /* Ensure an orderly disconnect occurs before final destruction */
    aeap_transport_disconnect(transport);
 
    transport->vtable->destroy(transport);
 
    ast_mutex_destroy(&transport->read_lock);
    ast_mutex_destroy(&transport->write_lock);
 
    ast_free(transport);
}
 
intmax_t aeap_transport_read(struct aeap_transport *transport, void *buf, intmax_t size,
    enum AST_AEAP_DATA_TYPE *rtype)
{
    SCOPED_MUTEX(lock, &transport->read_lock);
 
    if (!aeap_transport_is_connected(transport)) {
        return 0;
    }
 
    return transport->vtable->read(transport, buf, size, rtype);
}
 
intmax_t aeap_transport_write(struct aeap_transport *transport, const void *buf, intmax_t size,
    enum AST_AEAP_DATA_TYPE wtype)
{
    SCOPED_MUTEX(lock, &transport->write_lock);
 
    if (!aeap_transport_is_connected(transport)) {
        return 0;
    }
 
    return transport->vtable->write(transport, buf, size, wtype);
}