get the IP-addr out from an int32_t value

Ephracis · 02-08-2005, 09:58 AM

I am playing around with utmp and I saw these two lines in the man:

Code:

int32_t ut_addr_v6[4];      /* IP address of remote host.  */
#define ut_addr ut_addr_v6[0]

Now, I have never heard of the type int32_t. Since the first index in the array is used to define ut_addr for backward compatibility I thought that index would explain something or at least give a clue.

I got the value 1387536345 which still not make a lot of sense to me.

I would like to get something so I can use inet_ntoa() or simular to get a v4 IP-addr.

Matir · 02-08-2005, 10:16 AM

ut_addr_v6[0] is a 32-bit value (int32_t) containing the 4 bytes of the ip address in, I believe, host order. The following *SHOULD* work, I think:

Code:

inet_ntoa((struct in_addr)ut_addr_v6[0]);

Some minor modification may be neccessary.

Ephracis · 02-08-2005, 10:37 AM

Hm, I tried to play with that but I always get the error

Code:

error: no matching function for call to `in_addr::in_addr(
   int32_t&)'
/usr/include/netinet/in.h:135: error: candidates are: in_addr::in_addr()
/usr/include/netinet/in.h:135: error:                 in_addr::in_addr(const 
   in_addr&)

This must mean that I can't convert int32_t to in_addr that easy, right?

EDIT:
It was easy. Just assign the value of ut_addr_v6[0] to the s_addr in the inet_addr structure and then use that with inet_ntoa() to get the ip. :)

Code:

in_addr ipnetw;
ipnetw.s_addr = entry->ut_addr_v6[0];
string ipaddr = inet_ntoa(ipnetw);

gr33ndata · 02-09-2005, 09:03 AM

BTW, Is there and equivalent function to inet_ntoa() in the kernel space?