xl/libxl: add gatewaydev/netdev to vif specification

This option is used by the vif-route hotplug script. A new more
descriptive name is used, "gatewaydev", but "netdev" is also supported
as a deprecated backwards compatible option.

This option was supported in the past, according to
http://wiki.xen.org/wiki/Vif-route, so we should also support it in
libxl.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Tested-by: Ulf Kreutzberg <ulf.kreutzberg@hosteurope.de>
Cc: Ulf Kreutzberg <ulf.kreutzberg@hosteurope.de>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: George Dunlap <george.dunlap@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

docs/misc/xl-network-configuration.markdown

@@ -67,6 +67,15 @@ added to. The default is `xenbr0`. The bridge must be configured using
 your distribution's network configuration tools. See the [wiki][net]
 for guidance and examples.
 
+### gatewaydev
+
+Specifies the name of the network interface which has an IP and which
+is in the network the VIF should communicate with. This is used in the host
+by the vif-route hotplug script. See [wiki][vifroute] for guidance and
+examples.
+
+NOTE: netdev is a deprecated alias of this option.
+
 ### type
 
 This keyword is valid for HVM guests only.
@@ -158,3 +167,4 @@ on the underlying netback implementation.
 
 [oui]: http://en.wikipedia.org/wiki/Organizationally_Unique_Identifier
 [net]: http://wiki.xen.org/wiki/HostConfiguration/Networking
+[vifroute]: http://wiki.xen.org/wiki/Vif-route

tools/libxl/libxl.c

@@ -2829,7 +2829,7 @@ void libxl__device_nic_add(libxl__egc *egc, uint32_t domid,
     if (rc) goto out;
 
     front = flexarray_make(gc, 16, 1);
-    back = flexarray_make(gc, 16, 1);
+    back = flexarray_make(gc, 18, 1);
 
     if (nic->devid == -1) {
         if ((nic->devid = libxl__device_nextid(gc, domid, "vif") < 0)) {
@@ -2865,6 +2865,10 @@ void libxl__device_nic_add(libxl__egc *egc, uint32_t domid,
         flexarray_append(back, "ip");
         flexarray_append(back, libxl__strdup(gc, nic->ip));
     }
+    if (nic->gatewaydev) {
+        flexarray_append(back, "gatewaydev");
+        flexarray_append(back, libxl__strdup(gc, nic->gatewaydev));
+    }
 
     if (nic->rate_interval_usecs > 0) {
         flexarray_append(back, "rate");

tools/libxl/libxl_linux.c

@@ -84,11 +84,16 @@ static char **get_hotplug_env(libxl__gc *gc,
                               char *script, libxl__device *dev)
 {
     const char *type = libxl__device_kind_to_string(dev->backend_kind);
+    char *be_path = libxl__device_backend_path(gc, dev);
     char **env;
+    char *gatewaydev;
     int nr = 0;
     libxl_nic_type nictype;
 
-    const int arraysize = 13;
+    gatewaydev = libxl__xs_read(gc, XBT_NULL, GCSPRINTF("%s/%s", be_path,
+                                                        "gatewaydev"));
+
+    const int arraysize = 15;
     GCNEW_ARRAY(env, arraysize);
     env[nr++] = "script";
     env[nr++] = script;
@@ -98,6 +103,8 @@ static char **get_hotplug_env(libxl__gc *gc,
     env[nr++] = GCSPRINTF("backend/%s/%u/%d", type, dev->domid, dev->devid);
     env[nr++] = "XENBUS_BASE_PATH";
     env[nr++] = "backend";
+    env[nr++] = "netdev";
+    env[nr++] = gatewaydev ? : "";
     if (dev->backend_kind == LIBXL__DEVICE_KIND_VIF) {
         if (libxl__nic_type(gc, dev, &nictype)) {
             LOG(ERROR, "unable to get nictype");

tools/libxl/libxl_types.idl

@@ -385,6 +385,7 @@ libxl_device_nic = Struct("device_nic", [
     ("nictype", libxl_nic_type),
     ("rate_bytes_per_interval", uint64),
     ("rate_interval_usecs", uint32),
+    ("gatewaydev", string),
     ])
 
 libxl_device_pci = Struct("device_pci", [

tools/libxl/xl_cmdimpl.c

@@ -1210,6 +1210,14 @@ static void parse_config_data(const char *config_source,
                     parse_vif_rate(&config, (p2 + 1), nic);
                 } else if (!strcmp(p, "accel")) {
                     fprintf(stderr, "the accel parameter for vifs is currently not supported\n");
+                } else if (!strcmp(p, "netdev")) {
+                    fprintf(stderr, "the netdev parameter is deprecated, "
+                                    "please use gatewaydev instead\n");
+                    free(nic->gatewaydev);
+                    nic->gatewaydev = strdup(p2 + 1);
+                } else if (!strcmp(p, "gatewaydev")) {
+                    free(nic->gatewaydev);
+                    nic->gatewaydev = strdup(p2 + 1);
                 }
             } while ((p = strtok(NULL, ",")) != NULL);
 skip_nic:
@@ -5494,6 +5502,12 @@ int main_networkattach(int argc, char **argv)
             }
         } else if (MATCH_OPTION("bridge", *argv, oparg)) {
             replace_string(&nic.bridge, oparg);
+        } else if (MATCH_OPTION("netdev", *argv, oparg)) {
+            fprintf(stderr, "the netdev parameter is deprecated, "
+                            "please use gatewaydev instead\n");
+            replace_string(&nic.gatewaydev, oparg);
+        } else if (MATCH_OPTION("gatewaydev", *argv, oparg)) {
+            replace_string(&nic.gatewaydev, oparg);
         } else if (MATCH_OPTION("ip", *argv, oparg)) {
             replace_string(&nic.ip, oparg);
         } else if (MATCH_OPTION("script", *argv, oparg)) {