>>>>> On Thu, 20 Jan 2000 09:20:58 +0000,
>>>>> Philip Blundell <[EMAIL PROTECTED]> said:
>>>> Sockaddr_in6 does not fit in ifreq{} in BSDs, either. But it doesn't
>>>> matter for us if we carefully parse the result of the ioctl.
>>
>>> I remember that application increments its pointer manually by
>>> sizeof(struct sockaddr_in6) - sizeof(struct sockaddr) bytes,
>>> but it is not good for Linux because we don't know the actual size of
>>> sockaddr_in6 structure returned from kernel
>>
>> I don't get it. Why can't you just use sizeof(sockaddr_in6) for
>> AF_INET6? Are you concerned with padding issues?
> The returned structure includes (essentially) an array of `struct sockaddr'.
> You can't just vary the size of this structure since the user program would
> then have no way to find elements beyond the first. (For 4.4BSD this is not
> a
> problem because you can use sa->sa_len to get this information.)
I may still misunderstand the point, but I think you can calculate the
offset (i.e. sizeof(struct sockaddr_in6)) if you first check the
sa_family likt the following code:
struct ifconf ifconf;
struct ifreq *ifrp;
ioctl(sockt, SIOCGIFCONF, (char *)&ifconf);
for (i = 0; i < ifconf.ifc_len; i += sizeof(struct ifreq)) {
ifrp = (struct ifreq *)(ifconfg.ifc_buf + i);
.../* use ifrp as you want */
if (ifrp->ifr_addr.sa_family == AF_INET6) /* you may need more cases */
i += (sizeof(struct sockaddr_in6) - sizeof(struct sockaddr));
}
JINMEI, Tatuya
Communication Platform Lab.
Corporate R&D Center, Toshiba Corp.
[EMAIL PROTECTED]
