filter-rewriter: track connection and parse packet

We use net/colo.h to track connection and parse packet

Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

net/colo.c

@@ -114,6 +114,20 @@ void fill_connection_key(Packet *pkt, ConnectionKey *key)
     }
 }
 
+void reverse_connection_key(ConnectionKey *key)
+{
+    struct in_addr tmp_ip;
+    uint16_t tmp_port;
+
+    tmp_ip = key->src;
+    key->src = key->dst;
+    key->dst = tmp_ip;
+
+    tmp_port = key->src_port;
+    key->src_port = key->dst_port;
+    key->dst_port = tmp_port;
+}
+
 Connection *connection_new(ConnectionKey *key)
 {
     Connection *conn = g_slice_new(Connection);

net/colo.h

@@ -68,6 +68,7 @@ uint32_t connection_key_hash(const void *opaque);
 int connection_key_equal(const void *opaque1, const void *opaque2);
 int parse_packet_early(Packet *pkt);
 void fill_connection_key(Packet *pkt, ConnectionKey *key);
+void reverse_connection_key(ConnectionKey *key);
 Connection *connection_new(ConnectionKey *key);
 void connection_destroy(void *opaque);
 Connection *connection_get(GHashTable *connection_track_table,

net/filter-rewriter.c

@@ -44,6 +44,20 @@ static void filter_rewriter_flush(NetFilterState *nf)
     }
 }
 
+/*
+ * Return 1 on success, if return 0 means the pkt
+ * is not TCP packet
+ */
+static int is_tcp_packet(Packet *pkt)
+{
+    if (!parse_packet_early(pkt) &&
+        pkt->ip->ip_p == IPPROTO_TCP) {
+        return 1;
+    } else {
+        return 0;
+    }
+}
+
 static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
                                          NetClientState *sender,
                                          unsigned flags,
@@ -51,11 +65,47 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
                                          int iovcnt,
                                          NetPacketSent *sent_cb)
 {
+    RewriterState *s = FILTER_COLO_REWRITER(nf);
+    Connection *conn;
+    ConnectionKey key;
+    Packet *pkt;
+    ssize_t size = iov_size(iov, iovcnt);
+    char *buf = g_malloc0(size);
+
+    iov_to_buf(iov, iovcnt, 0, buf, size);
+    pkt = packet_new(buf, size);
+
     /*
      * if we get tcp packet
      * we will rewrite it to make secondary guest's
      * connection established successfully
      */
+    if (pkt && is_tcp_packet(pkt)) {
+
+        fill_connection_key(pkt, &key);
+
+        if (sender == nf->netdev) {
+            /*
+             * We need make tcp TX and RX packet
+             * into one connection.
+             */
+            reverse_connection_key(&key);
+        }
+        conn = connection_get(s->connection_track_table,
+                              &key,
+                              NULL);
+
+        if (sender == nf->netdev) {
+            /* NET_FILTER_DIRECTION_TX */
+            /* handle_primary_tcp_pkt */
+        } else {
+            /* NET_FILTER_DIRECTION_RX */
+            /* handle_secondary_tcp_pkt */
+        }
+    }
+
+    packet_destroy(pkt, NULL);
+    pkt = NULL;
     return 0;
 }