#include <fcntl.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <unistd.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));

  ifr.ifr_flags = IFF_TAP | IFF_MULTI_QUEUE;
  if(*dev) {
    strncpy(ifr.ifr_name, dev, IFNAMSIZ);
  }

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

   return fd;
}

int main(int argc, char* argv[]) {
  int tap_fd;
  char tap_name[IFNAMSIZ];
  char buffer[4096];
  strcpy(tap_name, "taptest");
  tap_fd = tap_alloc(tap_name);

  if(tap_fd < 0) {
    perror("Error while allocating the tap interface");
    exit(1);
  }

  while(1) {
    int nread = read(tap_fd,buffer,sizeof(buffer));
    if (nread < 0) {
      perror("Error while reading from tap");
      close(tap_fd);
      exit(1);
    }
    printf("Read %d bytes from device %s\n", nread, tap_name);
  }
}