+static int router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size_t len)
+{
+ struct icmp6_hdr *hdr = (struct icmp6_hdr *)data;
+ struct icmpv6_opt *opt;
+ size_t optlen = len - sizeof(*hdr);
+
+ /* Hoplimit is already checked in odhcpd_receive_packets */
+ if (len < sizeof(*hdr))
+ return 0;
+
+ if (hdr->icmp6_code)
+ return 0;
+
+ switch (hdr->icmp6_type) {
+ case ND_ROUTER_ADVERT:
+ if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
+ return 0;
+
+ opt = (struct icmpv6_opt *)((struct nd_router_advert *)data + 1);
+ break;
+
+ case ND_ROUTER_SOLICIT:
+ opt = (struct icmpv6_opt *)((struct nd_router_solicit *)data + 1);
+ break;
+
+ default:
+ return 0;
+ }
+
+ while (optlen > 0) {
+ size_t l = opt->len << 3;
+
+ if (optlen < sizeof(*opt))
+ return 0;
+
+ if (l > optlen || l == 0)
+ return 0;
+
+ if (opt->type == ND_OPT_SOURCE_LINKADDR && IN6_IS_ADDR_UNSPECIFIED(&source->sin6_addr) &&
+ hdr->icmp6_type == ND_ROUTER_SOLICIT) {
+ return 0;
+ }
+
+ opt = (struct icmpv6_opt *)(((uint8_t *)opt) + l);
+
+ optlen -= l;
+ }
+
+ return 1;
+}