Add `vlan' string field to libxl_device_nic, to allow a VLAN
configuration to be specified for the VIF when adding it to the
bridge device.

Update libxl_nic.c to read and write the vlan field from the
xenstore.

This provides the capability for supported operating systems (e.g.
Linux) to perform VLAN filtering on bridge ports.  The Xen
hotplug scripts need to be updated to read this information from
the xenstore and perform the required configuration.

Signed-off-by: Leigh Brown <leigh@solinno.co.uk>
Reviewed-by: Jason Andryuk <jandryuk@gmail.com>

---
 tools/libs/light/libxl_nic.c     | 10 ++++++++++
 tools/libs/light/libxl_types.idl |  1 +
 2 files changed, 11 insertions(+)

diff --git a/tools/libs/light/libxl_nic.c b/tools/libs/light/libxl_nic.c
index d6bf06fc34..d861e3726d 100644
--- a/tools/libs/light/libxl_nic.c
+++ b/tools/libs/light/libxl_nic.c
@@ -233,6 +233,11 @@ static int libxl__set_xenstore_nic(libxl__gc *gc, uint32_t domid,
         flexarray_append(back, GCSPRINTF("%u", nic->mtu));
     }
     
+    if (nic->vlan) {
+        flexarray_append(back, "vlan");
+        flexarray_append(back, libxl__strdup(gc, nic->vlan));
+    }
+
     flexarray_append(back, "bridge");
     flexarray_append(back, libxl__strdup(gc, nic->bridge));
     flexarray_append(back, "handle");
@@ -313,6 +318,11 @@ static int libxl__nic_from_xenstore(libxl__gc *gc, const char *libxl_path,
         nic->mtu = LIBXL_DEVICE_NIC_MTU_DEFAULT;
     }
 
+    rc = libxl__xs_read_checked(gc, XBT_NULL,
+                                GCSPRINTF("%s/vlan", libxl_path),
+				(const char **)(&nic->vlan));
+    if (rc) goto out;
+
     rc = libxl__xs_read_checked(gc, XBT_NULL,
                                 GCSPRINTF("%s/mac", libxl_path), &tmp);
     if (rc) goto out;
diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl
index 7d8bd5d216..5c510dc272 100644
--- a/tools/libs/light/libxl_types.idl
+++ b/tools/libs/light/libxl_types.idl
@@ -809,6 +809,7 @@ libxl_device_nic = Struct("device_nic", [
     ("backend_domname", string),
     ("devid", libxl_devid),
     ("mtu", integer),
+    ("vlan", string),
     ("model", string),
     ("mac", libxl_mac),
     ("ip", string),
-- 
2.39.2