init/cleanup of netfilter object

Add a netfilter object based on QOM.

A netfilter is attached to a netdev, captures all network packets
that pass through the netdev. When we delete the netdev, we also
delete the netfilter object attached to it, because if the netdev is
removed, the filter which attached to it is useless.

Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

include/net/filter.h

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2015 FUJITSU LIMITED
+ * Author: Yang Hongyang <yanghy@cn.fujitsu.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#ifndef QEMU_NET_FILTER_H
+#define QEMU_NET_FILTER_H
+
+#include "qom/object.h"
+#include "qemu-common.h"
+#include "qemu/typedefs.h"
+#include "net/queue.h"
+
+#define TYPE_NETFILTER "netfilter"
+#define NETFILTER(obj) \
+    OBJECT_CHECK(NetFilterState, (obj), TYPE_NETFILTER)
+#define NETFILTER_GET_CLASS(obj) \
+    OBJECT_GET_CLASS(NetFilterClass, (obj), TYPE_NETFILTER)
+#define NETFILTER_CLASS(klass) \
+    OBJECT_CLASS_CHECK(NetFilterClass, (klass), TYPE_NETFILTER)
+
+typedef void (FilterSetup) (NetFilterState *nf, Error **errp);
+typedef void (FilterCleanup) (NetFilterState *nf);
+/*
+ * Return:
+ *   0: finished handling the packet, we should continue
+ *   size: filter stolen this packet, we stop pass this packet further
+ */
+typedef ssize_t (FilterReceiveIOV)(NetFilterState *nc,
+                                   NetClientState *sender,
+                                   unsigned flags,
+                                   const struct iovec *iov,
+                                   int iovcnt,
+                                   NetPacketSent *sent_cb);
+
+typedef struct NetFilterClass {
+    ObjectClass parent_class;
+
+    /* optional */
+    FilterSetup *setup;
+    FilterCleanup *cleanup;
+    /* mandatory */
+    FilterReceiveIOV *receive_iov;
+} NetFilterClass;
+
+
+struct NetFilterState {
+    /* private */
+    Object parent;
+
+    /* protected */
+    char *netdev_id;
+    NetClientState *netdev;
+    NetFilterDirection direction;
+    QTAILQ_ENTRY(NetFilterState) next;
+};
+
+#endif /* QEMU_NET_FILTER_H */

include/net/net.h

@@ -92,6 +92,7 @@ struct NetClientState {
     NetClientDestructor *destructor;
     unsigned int queue_index;
     unsigned rxfilter_notify_enabled:1;
+    QTAILQ_HEAD(, NetFilterState) filters;
 };
 
 typedef struct NICState {