[V10,17/20] filter-rewriter: handle checkpoint and failover event

diff --git a/net/colo-compare.c b/net/colo-compare.c
index b8c0240725..462e822be6 100644
--- a/net/colo-compare.c
+++ b/net/colo-compare.c
@@ -116,6 +116,12 @@  enum {
     SECONDARY_IN,
 };
 
+static void colo_compare_inconsistency_notify(void)
+{
+    notifier_list_notify(&colo_compare_notifiers,
+                migrate_get_current());
+}
+
 static int compare_chr_send(CompareState *s,
                             const uint8_t *buf,
                             uint32_t size,
@@ -562,12 +568,6 @@  static int colo_old_packet_check_one(Packet *pkt, int64_t *check_time)
     }
 }
 
-static void colo_compare_inconsistency_notify(void)
-{
-    notifier_list_notify(&colo_compare_notifiers,
-                migrate_get_current());
-}
-
 void colo_compare_register_notifier(Notifier *notify)
 {
     notifier_list_add(&colo_compare_notifiers, notify);
diff --git a/net/colo.c b/net/colo.c
index 97c8fc928f..49176bf07b 100644
--- a/net/colo.c
+++ b/net/colo.c
@@ -221,3 +221,11 @@  Connection *connection_get(GHashTable *connection_track_table,
 
     return conn;
 }
+
+bool connection_has_tracked(GHashTable *connection_track_table,
+                            ConnectionKey *key)
+{
+    Connection *conn = g_hash_table_lookup(connection_track_table, key);
+
+    return conn ? true : false;
+}
diff --git a/net/colo.h b/net/colo.h
index 0277e0e9ba..11c5226488 100644
--- a/net/colo.h
+++ b/net/colo.h
@@ -98,6 +98,8 @@  void connection_destroy(void *opaque);
 Connection *connection_get(GHashTable *connection_track_table,
                            ConnectionKey *key,
                            GQueue *conn_list);
+bool connection_has_tracked(GHashTable *connection_track_table,
+                            ConnectionKey *key);
 void connection_hashtable_reset(GHashTable *connection_track_table);
 Packet *packet_new(const void *data, int size, int vnet_hdr_len);
 void packet_destroy(void *opaque, void *user_data);
diff --git a/net/filter-rewriter.c b/net/filter-rewriter.c
index f18a71bf2e..c463a0c1d0 100644
--- a/net/filter-rewriter.c
+++ b/net/filter-rewriter.c
@@ -20,11 +20,15 @@ 
 #include "qemu/main-loop.h"
 #include "qemu/iov.h"
 #include "net/checksum.h"
+#include "net/colo.h"
+#include "migration/colo.h"
 
 #define FILTER_COLO_REWRITER(obj) \
     OBJECT_CHECK(RewriterState, (obj), TYPE_FILTER_REWRITER)
 
 #define TYPE_FILTER_REWRITER "filter-rewriter"
+#define FAILOVER_MODE_ON  true
+#define FAILOVER_MODE_OFF false
 
 typedef struct RewriterState {
     NetFilterState parent_obj;
@@ -32,8 +36,14 @@  typedef struct RewriterState {
     /* hashtable to save connection */
     GHashTable *connection_track_table;
     bool vnet_hdr;
+    bool failover_mode;
 } RewriterState;
 
+static void filter_rewriter_failover_mode(RewriterState *s)
+{
+    s->failover_mode = FAILOVER_MODE_ON;
+}
+
 static void filter_rewriter_flush(NetFilterState *nf)
 {
     RewriterState *s = FILTER_COLO_REWRITER(nf);
@@ -269,6 +279,13 @@  static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
              */
             reverse_connection_key(&key);
         }
+
+        /* After failover we needn't change new TCP packet */
+        if (s->failover_mode &&
+            connection_has_tracked(s->connection_track_table, &key)) {
+            goto out;
+        }
+
         conn = connection_get(s->connection_track_table,
                               &key,
                               NULL);
@@ -302,11 +319,49 @@  static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
         }
     }
 
+out:
     packet_destroy(pkt, NULL);
     pkt = NULL;
     return 0;
 }
 
+static void reset_seq_offset(gpointer key, gpointer value, gpointer user_data)
+{
+    Connection *conn = (Connection *)value;
+
+    conn->offset = 0;
+}
+
+static gboolean offset_is_nonzero(gpointer key,
+                                  gpointer value,
+                                  gpointer user_data)
+{
+    Connection *conn = (Connection *)value;
+
+    return conn->offset ? true : false;
+}
+
+static void colo_rewriter_handle_event(NetFilterState *nf, int event,
+                                       Error **errp)
+{
+    RewriterState *rs = FILTER_COLO_REWRITER(nf);
+
+    switch (event) {
+    case COLO_EVENT_CHECKPOINT:
+        g_hash_table_foreach(rs->connection_track_table,
+                            reset_seq_offset, NULL);
+        break;
+    case COLO_EVENT_FAILOVER:
+        if (!g_hash_table_find(rs->connection_track_table,
+                              offset_is_nonzero, NULL)) {
+            filter_rewriter_failover_mode(rs);
+        }
+        break;
+    default:
+        break;
+    }
+}
+
 static void colo_rewriter_cleanup(NetFilterState *nf)
 {
     RewriterState *s = FILTER_COLO_REWRITER(nf);
@@ -350,6 +405,7 @@  static void filter_rewriter_init(Object *obj)
     RewriterState *s = FILTER_COLO_REWRITER(obj);
 
     s->vnet_hdr = false;
+    s->failover_mode = FAILOVER_MODE_OFF;
     object_property_add_bool(obj, "vnet_hdr_support",
                              filter_rewriter_get_vnet_hdr,
                              filter_rewriter_set_vnet_hdr, NULL);
@@ -362,6 +418,7 @@  static void colo_rewriter_class_init(ObjectClass *oc, void *data)
     nfc->setup = colo_rewriter_setup;
     nfc->cleanup = colo_rewriter_cleanup;
     nfc->receive_iov = colo_rewriter_receive_iov;
+    nfc->handle_event = colo_rewriter_handle_event;
 }
 
 static const TypeInfo colo_rewriter_info = {