config: limit ra_mtu to 65535

[project/odhcpd.git] / src / odhcpd.c

diff --git a/src/odhcpd.c b/src/odhcpd.c
index 8a18fbf..8a1c66e 100644 (file)
--- a/src/odhcpd.c
+++ b/src/odhcpd.c
@@ -336,7 +336,7 @@ out:
        return ctxt.ret;
 }
 
-int odhcpd_get_linklocal_interface_address(int ifindex, struct in6_addr *lladdr)
+static int odhcpd_get_linklocal_interface_address(int ifindex, struct in6_addr *lladdr)
 {
        int status = -1;
        struct sockaddr_in6 addr = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, ifindex};
@@ -354,6 +354,51 @@ int odhcpd_get_linklocal_interface_address(int ifindex, struct in6_addr *lladdr)
        return status;
 }
 
+/*
+ * DNS address selection criteria order :
+ * - use IPv6 address with valid lifetime if none is yet selected
+ * - use IPv6 address with a preferred lifetime if the already selected IPv6 address is deprecated
+ * - use an IPv6 ULA address if the already selected IPv6 address is not an ULA address
+ * - use the IPv6 address with the longest preferred lifetime
+ */
+int odhcpd_get_interface_dns_addr(const struct interface *iface, struct in6_addr *addr)
+{
+       time_t now = odhcpd_time();
+       ssize_t m = -1;
+
+       for (size_t i = 0; i < iface->ia_addr_len; ++i) {
+               if (iface->ia_addr[i].valid <= (uint32_t)now)
+                       continue;
+
+               if (m < 0) {
+                       m = i;
+                       continue;
+               }
+
+               if (iface->ia_addr[m].preferred >= (uint32_t)now &&
+                               iface->ia_addr[i].preferred < (uint32_t)now)
+                       continue;
+
+               if (IN6_IS_ADDR_ULA(&iface->ia_addr[i].addr)) {
+                       if (!IN6_IS_ADDR_ULA(&iface->ia_addr[m].addr)) {
+                               m = i;
+                               continue;
+                       }
+               } else if (IN6_IS_ADDR_ULA(&iface->ia_addr[m].addr))
+                       continue;
+
+               if (iface->ia_addr[i].preferred > iface->ia_addr[m].preferred)
+                       m = i;
+       }
+
+       if (m >= 0) {
+               *addr = iface->ia_addr[m].addr;
+               return 0;
+       }
+
+       return odhcpd_get_linklocal_interface_address(iface->ifindex, addr);
+}
+
 int odhcpd_setup_route(const struct in6_addr *addr, const int prefixlen,
                const struct interface *iface, const struct in6_addr *gw,
                const uint32_t metric, const bool add)