#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <string.h>

int tap_alloc(char *dev)
{
	struct ifreq ifr;
	int fd, err;

	if ((fd = open("/dev/net/tun", O_RDWR)) < 0)
		return -1;

	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_TAP | IFF_NO_PI;
	if (*dev)
		strncpy(ifr.ifr_name, dev, IFNAMSIZ);

	if ((err = ioctl(fd, TUNSETIFF, (void *)&ifr)) < 0) {
		close(fd);
		return err;
	}

	strcpy(dev, ifr.ifr_name);
	return fd;
}