Add iface.[ch]

src/tun.c

@@ -239,29 +239,6 @@ tun_write(int fd, const void *data, size_t size)
 #endif
 }
 
-int
-tun_set_mtu(char *dev_name, int mtu)
-{
-    struct ifreq ifr = {
-        .ifr_mtu = mtu,
-    };
-
-    str_cpy(ifr.ifr_name, dev_name, IFNAMSIZ - 1);
-
-    int fd = socket(AF_INET, SOCK_DGRAM, 0);
-
-    if (fd == -1)
-        return -1;
-
-    int ret = ioctl(fd, SIOCSIFMTU, &ifr);
-
-    int err = errno;
-    close(fd);
-    errno = err;
-
-    return ret;
-}
-
 int
 tun_set_persist(int fd, int on)
 {