[fpc-pascal] TUN/TAP

[Henry Vermaak]

2009/10/3 Jorge Aldo G. de F. Junior <jagfj80 at gmail.com>:
> Can anyone help me decypher the following code :
>
> int tun_alloc(char *dev)
>   {
>       struct ifreq ifr;

First, you need to get a pascal definition of struct ifreq, so look in
/usr/include/linux/if.h and translate it to pascal (or try and use
h2pas).

>       int fd, err;
>
>       if( (fd = open("/dev/net/tun", O_RDWR)) < 0 )
>          return tun_alloc_old(dev);

You will have to use fpopen here.

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

Use fillchar.

>
>       /* Flags: IFF_TUN   - TUN device (no Ethernet headers)
>        *        IFF_TAP   - TAP device
>        *
>        *        IFF_NO_PI - Do not provide packet information
>
>        */

These flags are defined int /sys/include/linux/if_tun.h.

>       ifr.ifr_flags = IFF_TUN;
>       if( *dev )
>          strncpy(ifr.ifr_name, dev, IFNAMSIZ);

ifr_name is defined to be ifr_ifrn.ifrn_name in if.h.

>
>       if( (err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0 ){

lol.  TUNSETIFF (_IOW('T', 202, int)) is generated by the various
macros in /usr/include/asm-generic/ioctl.h.  Work it out, or write a c
program to give you the number.  Then use fpioctl.

The rest should be straight forward.

Henry