+ return htons((uint16_t) sum);
+}
+
+void send_ipv6_ra(sessionidt s, tunnelidt t, struct in6_addr *ip)
+{
+ struct nd_opt_prefix_info *pinfo;
+ struct ip6_hdr *p_ip6_hdr;
+ struct nd_router_advert *p_nra;
+ uint8_t b[MAXETHER + 20];
+ struct ipv6_pseudo_hdr pseudo_hdr;
+ int l;
+
+ LOG(3, s, t, "Sending IPv6 RA\n");
+
+ memset(b, 0, sizeof(b));
+ p_ip6_hdr = (struct ip6_hdr *) makeppp(b, sizeof(b), 0, 0, s, t, PPPIPV6, 0, 0, 0);
+
+ if (!p_ip6_hdr)
+ {
+ LOG(3, s, t, "failed to send IPv6 RA\n");
+ return;
+ }
+
+ p_ip6_hdr->ip6_vfc = 0x60; // IPv6
+ p_ip6_hdr->ip6_plen = 0; // Length of payload (not header) (calculation below)
+ p_ip6_hdr->ip6_nxt = IPPROTO_ICMPV6; // icmp6 is next
+ p_ip6_hdr->ip6_hlim = 255; // Hop limit
+ // IPv6 0xFE80::1
+ inet_pton(AF_INET6, "FE80::1", &p_ip6_hdr->ip6_src.s6_addr);
+
+ if (ip != NULL)
+ {
+ memcpy(p_ip6_hdr->ip6_dst.s6_addr, ip, 16); // dest = ip
+ }
+ else
+ {
+ // FF02::1 - all hosts
+ inet_pton(AF_INET6, "FF02::1", &p_ip6_hdr->ip6_dst.s6_addr);
+ }
+
+ // RA message after Ipv6 header
+ p_nra = (struct nd_router_advert *) &p_ip6_hdr[1];
+ p_nra->nd_ra_type = ND_ROUTER_ADVERT; // RA message (134)
+ p_nra->nd_ra_code = 0; // Code
+ p_nra->nd_ra_cksum = 0; // Checksum
+ p_nra->nd_ra_curhoplimit = 64; // Hop count
+ p_nra->nd_ra_flags_reserved = (ND_RA_FLAG_MANAGED|ND_RA_FLAG_OTHER); // Flags
+ p_nra->nd_ra_router_lifetime = 0xFFFF; // Lifetime
+ p_nra->nd_ra_reachable = 0; // Reachable time
+ p_nra->nd_ra_retransmit = 0; // Retrans timer
+ // Option PI after RA message (rfc4861)
+ pinfo = (struct nd_opt_prefix_info *) &p_nra[1];
+ pinfo->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
+ pinfo->nd_opt_pi_len = 4;
+ pinfo->nd_opt_pi_flags_reserved = ND_OPT_PI_FLAG_ONLINK | ND_OPT_PI_FLAG_AUTO;
+ pinfo->nd_opt_pi_valid_time = htonl(2592000);
+ pinfo->nd_opt_pi_preferred_time = htonl(604800);
+ pinfo->nd_opt_pi_reserved2 = 0;
+ pinfo->nd_opt_pi_prefix_len = 64; // prefix length
+ pinfo->nd_opt_pi_prefix = config->ipv6_prefix;
+
+ // // Length of payload (not header)
+ p_ip6_hdr->ip6_plen = htons(sizeof(*pinfo) + sizeof(*p_nra));
+
+ l = sizeof(*pinfo) + sizeof(*p_nra) + sizeof(*p_ip6_hdr);
+
+ /* Use pseudo hearder for checksum calculation */
+ memset(&pseudo_hdr, 0, sizeof(pseudo_hdr));
+ memcpy(&pseudo_hdr.src, &p_ip6_hdr->ip6_src, 16);
+ memcpy(&pseudo_hdr.dest, &p_ip6_hdr->ip6_dst, 16);
+ pseudo_hdr.ulp_length = htonl(sizeof(*pinfo) + sizeof(*p_nra)); // Lenght whitout Ipv6 header
+ pseudo_hdr.nexthdr = IPPROTO_ICMPV6;
+ // Checksum is over the icmp6 payload plus the pseudo header
+ p_nra->nd_ra_cksum = ipv6_checksum(&pseudo_hdr, (uint8_t *) p_nra, (sizeof(*pinfo) + sizeof(*p_nra)));
+
+ tunnelsend(b, l + (((uint8_t *) p_ip6_hdr)-b), t); // send it...
+ return;