文件传输

Question

请问以下文件发送和接收代码运行后，文件打不开，出现头文件被破坏，请高人指点！
发送文件：
   FileStream fs1 = new FileStream(openFileDialog1.FileName, FileMode.Open, FileAccess.Read);
            BinaryReader br1 = new BinaryReader(fs1);//将文件流数据读做二进制值
            long filelength = fs1.Length;
            int times = (Int32)(filelength / 5120);
            if ((long)(times * 5120) < filelength)//如果文件总长度不是5K的整数倍那么就把循环次数加以
            {
                times = times + 1;
            }
            //设置进度条
            this.progressBar1.Maximum = times;
            this.progressBar1.Minimum = 0;
            //开始发送文件
            byte[] tcp_byte = null;
            int finishtimes = 0;
            while (finishtimes < times)
            {
                try
                {
                    if (finishtimes < times - 1)//进行前times-1次循环
                    {
                        tcp_byte = new byte[5120];
                        br1.Read(tcp_byte, 0, 5120);//将二进制流顺序读入字节数组以便发送
                    }
                    else //finishtimes=times-1以下执行最后一次循环
                    {
                        //最后一次所剩的数据字节数
                        Int32 intby = (Int32)(filelength - (long)finishtimes * 5120);
                        tcp_byte = new byte[intby];
                        br1.Read(tcp_byte, 0, tcp_byte.Length);
                    }
                    //向接收端发送5k字节的数据
                    Link.SendToServer(filens, tcp_byte);
                    for (int i = 0; i < 30000; i++)
                    {
                        //接收对方的确认信息 
                        string content = Link.ReceiveFromServer(filens);
                        if ((content != "") && (i < 20000))
                        {
                            string[] strflag = content.Split(new char[] { '|' });
                            //如果上一段5k数据发送成功，则对方回复next|,否则等待
                            if (strflag[0] == "next")
                            {
                                finishtimes = finishtimes + 1;
                            }
                            this.progressBar1.Value = finishtimes;
                            break;
                        }
                        if (i == 20000)
                        {
                            if (finishtimes < times - 1)//进行前times-1次循环
                            {
                                tcp_byte = new byte[5120];
                                br1.Read(tcp_byte, 0, 5120);//将二进制流顺序读入字节数组以便发送
                            }
                            else //finishtimes=times-1以下执行最后一次循环
                            {
                                //最后一次所剩的数据字节数
                                Int32 intby = (Int32)(filelength - (long)finishtimes * 5120);
                                tcp_byte = new byte[intby];
                                br1.Read(tcp_byte, 0, tcp_byte.Length);
                            }
                            //向接收端发送5k字节的数据
                            Link.SendToServer(filens, tcp_byte);
                            break;
                        }                    }                }
                catch
                {
                    break;
                }            }
            this.labfile.Text = "文件发送成功！";
            //关闭连接释放资源
            filelisten.Stop();
            filesocket.Close();
            filens.Close();
}
接收文件：
 string filetype = Path.GetExtension(file.filename);
            this.saveFileDialog1.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyComputer) + "//" + file.filename;
            this.saveFileDialog1.Filter = "文件类型*" + filetype + "*|" + filetype;
            this.saveFileDialog1.Title = "选择保存的路径";
            if (saveFileDialog1.ShowDialog() == DialogResult.OK)
            {
                FileStream fs1 = new FileStream(saveFileDialog1.FileName, FileMode.Create, FileAccess.Write);
                BinaryWriter bw1 = new BinaryWriter(fs1);
                long filelength = file.filesize;
                int times = (Int32)(filelength / 5120);//要循环的次数
                if ((long)times * 5120 < filelength)
                {
                    times = times + 1;
                }
                int finishtimes = 0;//已经循环的次数
                this.progressBar1.Maximum = times;
                this.progressBar1.Minimum = 0;
                while (finishtimes < times)
                {
                    byte[] tcpbyte = Link.ReceiveFromClient(NSwithClient);
                    bw1.Write(tcpbyte, 0, tcpbyte.Length);
                    bw1.Flush();
                    Link.SendToServer(NSwithClient, "next|");
                    finishtimes = finishtimes + 1;
                    this.progressBar1.Value = finishtimes;
                }
                //关闭流
                bw1.Close();
                bw1 = null;
                fs1.Close(); fs1 = null;
                MessageBox.Show("文件接收完毕!");
                //关闭与发送端的流通道
                NSwithClient.Close();
                //this.Close();}