Bug#966459: linux: traffic class socket options (both IPv4/IPv6) inconsistent with docs/standards

[Thorsten Glaser <t.glaser@tarent.de>]

On Mon, 3 Aug 2020, Thorsten Glaser wrote:

> keep the code I currently have that compares byte 0 and 3, using

Actually not. I’ve added some debugging code with…

static size_t
cmsg_actual_data_len(const struct cmsghdr *cmsg)
{
        union {
                const struct cmsghdr *cmsg;
                const unsigned char *uc;
        } ptr[(
                /* compile-time assertions */
                sizeof(socklen_t) <= sizeof(size_t)
            ) ? 1 : -1];
        ptrdiff_t pd;

        ptr[0].cmsg = cmsg;
        pd = CMSG_DATA(cmsg) - ptr[0].uc;
        return ((size_t)cmsg->cmsg_len - (size_t)pd);
}

… and dumping the received data on Linux and MidnightBSD
(the two systems I currently have access) and found varying
results but if this returns 4 I think I better consume an int.

bye,
//mirabilos
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