net/filter.c: Add Options to insert filters anywhere in the filter list

To switch the Secondary to Primary, we need to insert new filters
before the filter-rewriter.

Add the options insert= and position= to be able to insert filters
anywhere in the filter list.

position should be "head" or "tail" to insert at the head or
tail of the filter list or it should be "id=<id>" to specify
the id of another filter.
insert should be either "before" or "behind" to specify where to
insert the new filter relative to the one specified with position.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Zhang Chen <chen.zhang@intel.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

1 files changed, 91 insertions, 1 deletions

diff --git a/net/filter.c b/net/filter.c
index 4b932e79f9..8221666263 100644
--- a/net/filter.c
+++ b/net/filter.c
@@ -171,11 +171,47 @@ static void netfilter_set_status(Object *obj, const char *str, Error **errp)
     }
 }
 
+static char *netfilter_get_position(Object *obj, Error **errp)
+{
+    NetFilterState *nf = NETFILTER(obj);
+
+    return g_strdup(nf->position);
+}
+
+static void netfilter_set_position(Object *obj, const char *str, Error **errp)
+{
+    NetFilterState *nf = NETFILTER(obj);
+
+    nf->position = g_strdup(str);
+}
+
+static char *netfilter_get_insert(Object *obj, Error **errp)
+{
+    NetFilterState *nf = NETFILTER(obj);
+
+    return nf->insert_before_flag ? g_strdup("before") : g_strdup("behind");
+}
+
+static void netfilter_set_insert(Object *obj, const char *str, Error **errp)
+{
+    NetFilterState *nf = NETFILTER(obj);
+
+    if (strcmp(str, "before") && strcmp(str, "behind")) {
+        error_setg(errp, "Invalid value for netfilter insert, "
+                         "should be 'before' or 'behind'");
+        return;
+    }
+
+    nf->insert_before_flag = !strcmp(str, "before");
+}
+
 static void netfilter_init(Object *obj)
 {
     NetFilterState *nf = NETFILTER(obj);
 
     nf->on = true;
+    nf->insert_before_flag = false;
+    nf->position = g_strdup("tail");
 
     object_property_add_str(obj, "netdev",
                             netfilter_get_netdev_id, netfilter_set_netdev_id,
@@ -187,11 +223,18 @@ static void netfilter_init(Object *obj)
     object_property_add_str(obj, "status",
                             netfilter_get_status, netfilter_set_status,
                             NULL);
+    object_property_add_str(obj, "position",
+                            netfilter_get_position, netfilter_set_position,
+                            NULL);
+    object_property_add_str(obj, "insert",
+                            netfilter_get_insert, netfilter_set_insert,
+                            NULL);
 }
 
 static void netfilter_complete(UserCreatable *uc, Error **errp)
 {
     NetFilterState *nf = NETFILTER(uc);
+    NetFilterState *position = NULL;
     NetClientState *ncs[MAX_QUEUE_NUM];
     NetFilterClass *nfc = NETFILTER_GET_CLASS(uc);
     int queues;
@@ -219,6 +262,41 @@ static void netfilter_complete(UserCreatable *uc, Error **errp)
         return;
     }
 
+    if (strcmp(nf->position, "head") && strcmp(nf->position, "tail")) {
+        Object *container;
+        Object *obj;
+        char *position_id;
+
+        if (!g_str_has_prefix(nf->position, "id=")) {
+            error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "position",
+                       "'head', 'tail' or 'id=<id>'");
+            return;
+        }
+
+        /* get the id from the string */
+        position_id = g_strndup(nf->position + 3, strlen(nf->position) - 3);
+
+        /* Search for the position to insert before/behind */
+        container = object_get_objects_root();
+        obj = object_resolve_path_component(container, position_id);
+        if (!obj) {
+            error_setg(errp, "filter '%s' not found", position_id);
+            g_free(position_id);
+            return;
+        }
+
+        position = NETFILTER(obj);
+
+        if (position->netdev != ncs[0]) {
+            error_setg(errp, "filter '%s' belongs to a different netdev",
+                        position_id);
+            g_free(position_id);
+            return;
+        }
+
+        g_free(position_id);
+    }
+
     nf->netdev = ncs[0];
 
     if (nfc->setup) {
@@ -228,7 +306,18 @@ static void netfilter_complete(UserCreatable *uc, Error **errp)
             return;
         }
     }
-    QTAILQ_INSERT_TAIL(&nf->netdev->filters, nf, next);
+
+    if (position) {
+        if (nf->insert_before_flag) {
+            QTAILQ_INSERT_BEFORE(position, nf, next);
+        } else {
+            QTAILQ_INSERT_AFTER(&nf->netdev->filters, position, nf, next);
+        }
+    } else if (!strcmp(nf->position, "head")) {
+        QTAILQ_INSERT_HEAD(&nf->netdev->filters, nf, next);
+    } else if (!strcmp(nf->position, "tail")) {
+        QTAILQ_INSERT_TAIL(&nf->netdev->filters, nf, next);
+    }
 }
 
 static void netfilter_finalize(Object *obj)
@@ -245,6 +334,7 @@ static void netfilter_finalize(Object *obj)
         QTAILQ_REMOVE(&nf->netdev->filters, nf, next);
     }
     g_free(nf->netdev_id);
+    g_free(nf->position);
 }
 
 static void default_handle_event(NetFilterState *nf, int event, Error **errp)