zebra, lib/memtypes.c: the netlink sockets work per VRF

This patch lets the netlink sockets work per VRF.

* The definition of "struct nlsock" is moved into zebra/rib.h.

* The previous global variables "netlink" and "netlink_cmd" now
  become the members of "struct zebra_vrf", and are initialized
  in zebra_vrf_alloc().

* All relative functions now work for a specific VRF, by adding
  a new parameter which specifies the working VRF, except those
  functions in which the VRF ID can be obtained from the interface.

* kernel_init(), interface_list() and route_read() are now also
  working per VRF, and moved from main() to zebra_vrf_enable().

* A new function kernel_terminate() is added to release the
  netlink sockets. It is called from zebra_vrf_disable().

* Correct VRF ID, instead of the previous VRF_DEFAULT, are now
  passed to the functions of processing interfaces or route
  entries.

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: Donald Sharp <sharpd@cumulusnetworks.com>
diff --git a/zebra/zebra_rib.c b/zebra/zebra_rib.c
index 9d966a0..084af38 100644
--- a/zebra/zebra_rib.c
+++ b/zebra/zebra_rib.c
@@ -3447,6 +3447,9 @@
 zebra_vrf_alloc (vrf_id_t vrf_id)
 {
   struct zebra_vrf *zvrf;
+#ifdef HAVE_NETLINK
+  char nl_name[64];
+#endif
 
   zvrf = XCALLOC (MTYPE_ZEBRA_VRF, sizeof (struct zebra_vrf));
 
@@ -3463,6 +3466,17 @@
   /* Set VRF ID */
   zvrf->vrf_id = vrf_id;
 
+#ifdef HAVE_NETLINK
+  /* Initialize netlink sockets */
+  snprintf (nl_name, 64, "netlink-listen (vrf %u)", vrf_id);
+  zvrf->netlink.sock = -1;
+  zvrf->netlink.name = XSTRDUP (MTYPE_NETLINK_NAME, nl_name);
+
+  snprintf (nl_name, 64, "netlink-cmd (vrf %u)", vrf_id);
+  zvrf->netlink_cmd.sock = -1;
+  zvrf->netlink_cmd.name = XSTRDUP (MTYPE_NETLINK_NAME, nl_name);
+#endif
+
   return zvrf;
 }