net/net: properly handle multiple packets in net_fill_rstate()

When network is busy, we will receive multiple packets at one time. In
that situation, we should keep trying to do the receiving instead of
finalizing only the first packet.
Signed-off-by: NZhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: NLi Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>

net/net.c

@@ -1602,9 +1602,8 @@ void net_socket_rs_init(SocketReadState *rs,
 
 /*
  * Returns
- * 0: SocketReadState is not ready
- * 1: SocketReadState is ready
- * otherwise error occurs
+ * 0: success
+ * -1: error occurs
  */
 int net_fill_rstate(SocketReadState *rs, const uint8_t *buf, int size)
 {
@@ -1652,10 +1651,11 @@ int net_fill_rstate(SocketReadState *rs, const uint8_t *buf, int size)
                 if (rs->finalize) {
                     rs->finalize(rs);
                 }
-                return 1;
             }
             break;
         }
     }
+
+    assert(size == 0);
     return 0;
 }