zebra: maintain RTADV per VRF

This moves the global variable "rtadv" into the "struct zebra_vrf",
so that RTADV feature can work per VRF.

* rtadv.c/rtadv.h:

  Add a proper parameter to the functions so that the entity of the
  "struct zebra_vrf" and interfaces can be obtained from the specified
  VRF.

  The old rtadv_init() is splitted into:
  - rtadv_cmd_init(): it installs the RTADV commands; is called from
                      main();
  - new rtadv_init(): it creates the socket; is called from
                      zebra_vrf_enable().

  rtadv_terminate() is added to stop the threads, close the socket and
  clear the counters. It is called from zebra_vrf_disable().

  rtadv_make_socket() now calls vrf_socket() to create a socket in
  the VRF.

* interface.h and rib.h: define the macro RTADV.
* main.c: according changes, refer to rtadv.c.

Signed-off-by: Feng Lu <lu.feng@6wind.com>
Reviewed-by: Alain Ritoux <alain.ritoux@6wind.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Vincent JARDIN <vincent.jardin@6wind.com>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/zebra/rib.h b/zebra/rib.h
index 5663f30..9972941 100644
--- a/zebra/rib.h
+++ b/zebra/rib.h
@@ -332,6 +332,29 @@
   vrf_id_t vrf_id;
 };
 
+/* Router advertisement feature. */
+#ifndef RTADV
+#if (defined(LINUX_IPV6) && (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1)) || defined(KAME)
+  #ifdef HAVE_RTADV
+    #define RTADV
+  #endif
+#endif
+#endif
+
+#if defined (HAVE_IPV6) && defined (RTADV)
+/* Structure which hold status of router advertisement. */
+struct rtadv
+{
+  int sock;
+
+  int adv_if_count;
+  int adv_msec_if_count;
+
+  struct thread *ra_read;
+  struct thread *ra_timer;
+};
+#endif /* RTADV && HAVE_IPV6 */
+
 /* Routing table instance.  */
 struct zebra_vrf
 {
@@ -361,6 +384,10 @@
   struct list *rid_all_sorted_list;
   struct list *rid_lo_sorted_list;
   struct prefix rid_user_assigned;
+
+#if defined (HAVE_IPV6) && defined (RTADV)
+  struct rtadv rtadv;
+#endif /* RTADV && HAVE_IPV6 */
 };
 
 /*