ip6 = (struct ip6_hdr *)ip;
MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
ip6 = (struct ip6_hdr *)ip;
MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));