tunutil.hpp

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//    OpenVPN -- An application to securely tunnel IP networks
//               over a single port, with support for SSL/TLS-based
//               session authentication and key exchange,
//               packet encryption, packet authentication, and
//               packet compression.
//
//    Copyright (C) 2012- OpenVPN Inc.
//
//    SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
 
// Tun interface utilities for Mac OS X.
 
#ifndef OPENVPN_TUN_MAC_TUNUTIL_H
#define OPENVPN_TUN_MAC_TUNUTIL_H
 
#include <fcntl.h>
#include <errno.h>
 
#include <string>
 
#include <openvpn/common/size.hpp>
#include <openvpn/common/exception.hpp>
#include <openvpn/asio/asioerr.hpp>
#include <openvpn/common/to_string.hpp>
#include <openvpn/common/scoped_fd.hpp>
#include <openvpn/tun/layer.hpp>
 
namespace openvpn::TunMac::Util {
OPENVPN_EXCEPTION(tun_mac_util);
 
inline int tuntap_open(const Layer &layer, std::string &name)
{
    for (int i = 0; i < 256; ++i)
    {
        const char *tuntap;
        if (layer() == Layer::OSI_LAYER_3)
            tuntap = "tun";
        else if (layer() == Layer::OSI_LAYER_2)
            tuntap = "tap";
        else
            throw tun_mac_util("unknown OSI layer");
        const std::string node_str = tuntap + to_string(i);
        const std::string node_fn = "/dev/" + node_str;
 
        ScopedFD fd(open(node_fn.c_str(), O_RDWR));
        if (fd.defined())
        {
            // got it
            if (fcntl(fd(), F_SETFL, O_NONBLOCK) < 0)
                throw tun_mac_util("fcntl error on " + node_fn + " : " + errinfo(errno));
 
            name = node_str;
            return fd.release();
        }
    }
    throw tun_mac_util(std::string("error opening Mac ") + layer.dev_type() + " device");
}
 
} // namespace openvpn::TunMac::Util
 
#endif