+static bool 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, *end = (struct icmpv6_opt*)&data[len];
+
+ /* Hoplimit is already checked in odhcpd_receive_packets */
+ if (len < sizeof(*hdr) || hdr->icmp6_code)
+ return false;
+
+ switch (hdr->icmp6_type) {
+ case ND_ROUTER_ADVERT:
+ if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
+ return false;
+
+ 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 false;
+ }
+
+ icmpv6_for_each_option(opt, opt, end)
+ if (opt->type == ND_OPT_SOURCE_LINKADDR &&
+ IN6_IS_ADDR_UNSPECIFIED(&source->sin6_addr) &&
+ hdr->icmp6_type == ND_ROUTER_SOLICIT)
+ return false;
+
+ // Check all options parsed successfully
+ return opt == end;
+}