Function ip6_setpktopt

freebsd/netinet6/ip6_output.c:2883–3281

* Set a particular packet option, as a sticky option or an ancillary data * item. "len" can be 0 only when it's a sticky option. * We have 4 cases of combination of "sticky" and "cmsg": * "sticky=0, cmsg=0": impossible * "sticky=0, cmsg=1": RFC2292 or RFC3542 ancillary data * "sticky=1, cmsg=0": RFC3542 socket option * "sticky=1, cmsg=1": RFC2292 socket option */

 * "sticky=1, cmsg=1": RFC2292 socket option
 */
static int
ip6_setpktopt(int optname, u_char *buf, int len, struct ip6_pktopts *opt,
    struct ucred *cred, int sticky, int cmsg, int uproto)
{
	int minmtupolicy, preftemp;
	int error;

	if (!sticky && !cmsg) {
#ifdef DIAGNOSTIC
		printf("ip6_setpktopt: impossible case\n");
#endif
		return (EINVAL);
	}

	/*
	 * IPV6_2292xxx is for backward compatibility to RFC2292, and should
	 * not be specified in the context of RFC3542.  Conversely,
	 * RFC3542 types should not be specified in the context of RFC2292.
	 */
	if (!cmsg) {
		switch (optname) {
		case IPV6_2292PKTINFO:
		case IPV6_2292HOPLIMIT:
		case IPV6_2292NEXTHOP:
		case IPV6_2292HOPOPTS:
		case IPV6_2292DSTOPTS:
		case IPV6_2292RTHDR:
		case IPV6_2292PKTOPTIONS:
			return (ENOPROTOOPT);
		}
	}
	if (sticky && cmsg) {
		switch (optname) {
		case IPV6_PKTINFO:
		case IPV6_HOPLIMIT:
		case IPV6_NEXTHOP:
		case IPV6_HOPOPTS:
		case IPV6_DSTOPTS:
		case IPV6_RTHDRDSTOPTS:
		case IPV6_RTHDR:
		case IPV6_USE_MIN_MTU:
		case IPV6_DONTFRAG:
		case IPV6_TCLASS:
		case IPV6_PREFER_TEMPADDR: /* XXX: not an RFC3542 option */
			return (ENOPROTOOPT);
		}
	}

	switch (optname) {
	case IPV6_2292PKTINFO:
	case IPV6_PKTINFO:
	{
		struct ifnet *ifp = NULL;
		struct in6_pktinfo *pktinfo;

		if (len != sizeof(struct in6_pktinfo))
			return (EINVAL);