tun.cc

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#include "tun.hh"
 
#include "util.hh"
 
#include <cstring>
#include <fcntl.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <sys/ioctl.h>
 
static constexpr const char *CLONEDEV = "/dev/net/tun";
 
using namespace std;
 
 
TunTapFD::TunTapFD(const string &devname, const bool is_tun)
    : FileDescriptor(SystemCall("open", open(CLONEDEV, O_RDWR))) {
    struct ifreq tun_req {};
 
    tun_req.ifr_flags = (is_tun ? IFF_TUN : IFF_TAP) | IFF_NO_PI;  // tun device with no packetinfo
 
    // copy devname to ifr_name, making sure to null terminate
 
    strncpy(static_cast<char *>(tun_req.ifr_name), devname.data(), IFNAMSIZ - 1);
    tun_req.ifr_name[IFNAMSIZ - 1] = '\0';
 
    SystemCall("ioctl", ioctl(fd_num(), TUNSETIFF, static_cast<void *>(&tun_req)));
}