Re: Q: how to get out the PF_xxx of a socket

[JINMEI Tatuya / $B?@L@C#:H(B]

>>>>> On Fri, 08 Sep 2000 19:55:57 +0200, 
>>>>> Francis Dupont <[EMAIL PROTECTED]> said:

>    I want to write the macro IPPROTO_IPvX(s), returning IPPROTO_IP if the
>    socket's domain is PF_INET and IPPROTO_IPV6 if it's PF_INET6. 
   
>    I have been going trhough rfc2553 but couldn't find it. Does anybody
>    have a clue ?
   
> => RFC 2133 had it:

>    An application may use IPV6_ADDRFORM with getsockopt() to learn
>    whether an open socket is a PF_INET of PF_INET6 socket.  For example:

>        int  addrform;
>        size_t  len = sizeof(addrform);

>        if (getsockopt(s, IPPROTO_IPV6, IPV6_ADDRFORM,
>                       (char *) &addrform, &len) == -1)
>            perror("getsockopt IPV6_ADDRFORM");
>        else if (addrform == PF_INET)
>            printf("This is an IPv4 socket.\n");
>        else if (addrform == PF_INET6)
>            printf("This is an IPv6 socket.\n");
>        else
>            printf("This system is broken.\n");

But IPV6_ADDRFORM could be used only for a PF_INET6 socket. I guess
the original question asked a method to distinguish a "pure" PF_INET
socket from a PF_INET6 one.
(I know you don't recommend programmers to use such two-socket usage
model, though.)

                                        JINMEI, Tatuya
                                        Communication Platform Lab.
                                        Corporate R&D Center, Toshiba Corp.
                                        [EMAIL PROTECTED]

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