#include <linux/if.h>
#include <linux/if_tun.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <cstdlib>
#include <cstring>

#include "TunDevice.hpp"

TunDevice::TunDevice(const std::string& dev)
{
    struct ifreq ifr;
    int fd, err;

    if( (fd = open("/dev/net/tun", O_RDWR)) < 0 )
        throw TunDevice::InitializationError("Cannot open /dev/net/tun", fd);

    memset(&ifr, 0, sizeof(ifr));

    /* Flags: IFF_TUN   - TUN device (no Ethernet headers)
     *        IFF_TAP   - TAP device
     *
     *        IFF_NO_PI - Do not provide packet information
     */
    ifr.ifr_flags = IFF_TUN;
    if(!dev.empty()) {
        if(dev.size() >= IFNAMSIZ - 2)
            throw TunDevice::InitializationError("Device name is too long.");
        strncpy(ifr.ifr_name, dev.c_str(), IFNAMSIZ-1);
    }

    if( (err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0 ){
        close(fd);
        throw TunDevice::InitializationError(
                "Tunnel interface failed [TUNSETIFF]", err
                );
    }
    _dev_name = ifr.ifr_name;
    _fd = fd;
}

TunDevice::~TunDevice() {
    close(_fd);
}