IPV6_FLOWINFO_MASK
ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
(inp->in6p_flowinfo & IPV6_FLOWINFO_MASK);
if ((sin6->sin6_flowinfo & IPV6_FLOWINFO_MASK) != 0)
flowinfo = (u_int32_t)ntohl(ip6->ip6_flow & IPV6_FLOWINFO_MASK);
ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
(in6p->in6p_flowinfo & IPV6_FLOWINFO_MASK);
ip6->ip6_flow = in6p->in6p_flowinfo & IPV6_FLOWINFO_MASK;