_IOR/W with if_tun

From: bsder (snort_sam_at_yahoo.com)
Date: 10/29/05 

Date: Sat, 29 Oct 2005 19:22:09 +1000

Hi,

Can anyone tell me what does the following codes do:

/* ioctl's for get/set debug */
#define TUNSDEBUG _IOW('t', 90, int)
#define TUNGDEBUG _IOR('t', 89, int)
#define TUNSIFINFO _IOW('t', 91, struct tuninfo)
#define TUNGIFINFO _IOR('t', 92, struct tuninfo)
#define TUNSLMODE _IOW('t', 93, int)

I tried to find out the implementation of the _IOR/W functions, but I
found nothing in the src directory.

Can anyone please tell me where can I allocate the implemetation of
these _IOR/W functions?

Thanks
Sam