lib, vtysh: support multiple VRFs by using linux netns

We realize VRFs with linux netns by default. The main job is
to associate a VRF with a netns. Currently this is done by
the configuration:

  [no] vrf N netns <netns-name>

This command is also available in vtysh and goes to only
zebra, because presently only zebra supports multiple VRF.

A file descriptor is added to "struct vrf". This is for the
associated netns file. Once the command "vrf N netns NAME"
is executed, the specified file is opened and the file
descriptor is stored in the VRF N. In this way the
association is formed.

In vrf_socket(), we first switch to the specified VRF by
using the stored file descriptor, and then can allocate
a socket which is working in the associated netns.

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>

1 files changed, 8 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index f68d86fc..6da65f34 100755
--- a/configure.ac
+++ b/configure.ac
@@ -801,6 +801,14 @@ AC_CHECK_FUNCS(setproctitle, ,
   ]
 )
 
+AC_CHECK_HEADER([asm-generic/unistd.h],
+                [AC_CHECK_DECL(__NR_setns,
+                               AC_DEFINE(HAVE_NETNS,, Have netns),,
+                               QUAGGA_INCLUDES [#include <asm-generic/unistd.h>
+                               ])
+                 AC_CHECK_FUNCS(setns, AC_DEFINE(HAVE_SETNS,, Have setns))]
+               )
+
 dnl ------------------------------------
 dnl Determine routing get and set method
 dnl ------------------------------------