c#端口转发 断点传输文件

在 C# 中实现端口转发可以使用 TcpListener 和 TcpClient 类，而断点传输文件可以使用 FileStream 和 BinaryReader/BinaryWriter 类。

以下是一个简单的示例代码，演示了如何在本地端口监听并转发传入的连接：

using System;
using System.IO;
using System.Net;
using System.Net.Sockets;

class PortForwarder
{
    static void Main(string[] args)
    {
        int localPort = 1234; // 本地监听端口
        string remoteHost = "example.com"; // 转发目标主机
        int remotePort = 5678; // 转发目标端口

        TcpListener listener = new TcpListener(IPAddress.Any, localPort);
        listener.Start();
        Console.WriteLine("Listening on port " + localPort);

        while (true)
        {
            TcpClient client = listener.AcceptTcpClient();
            Console.WriteLine("Accepted connection from " + client.Client.RemoteEndPoint);

            TcpClient remoteClient = new TcpClient(remoteHost, remotePort);
            Console.WriteLine("Connected to remote host " + remoteHost + ":" + remotePort);

            // 开启一个后台线程，将两个连接之间的数据进行转发
            System.Threading.Thread thread = new System.Threading.Thread(() =>
            {
                try
                {
                    using (var localStream = client.GetStream())
                    using (var remoteStream = remoteClient.GetStream())
                    {
                        byte[] buffer = new byte[4096];
                        int bytesRead;
                        while ((bytesRead = localStream.Read(buffer, 0, buffer.Length)) > 0)
                        {
                            remoteStream.Write(buffer, 0, bytesRead);
                        }
                    }
                }
                catch (Exception ex)
                {
                    Console.WriteLine("Error: " + ex.ToString());
                }
                finally
                {
                    client.Dispose();
                    remoteClient.Dispose();
                }
            });
            thread.IsBackground = true;
            thread.Start();
        }
    }
}

要实现断点传输文件，可以根据需要进行读取和写入文件的偏移量，并在 TcpClient 之间进行数据传输。以下是一个简单的示例代码：

using System;
using System.IO;
using System.Net;
using System.Net.Sockets;

class FileTransfer
{
    static void Main(string[] args)
    {
        string localFilePath = "localfile.dat"; // 本地文件路径
        string remoteHost = "example.com"; // 文件接收主机
        int remotePort = 5678; // 文件接收端口

        long offset = 0; // 起始偏移量

        TcpClient client = new TcpClient(remoteHost, remotePort);
        Console.WriteLine("Connected to remote host " + remoteHost + ":" + remotePort);

        using (var fileStream = new FileStream(localFilePath, FileMode.Open, FileAccess.Read))
        using (var reader = new BinaryReader(fileStream))
        using (var writer = new BinaryWriter(client.GetStream()))
        {
            // 将文件读取指定偏移量
            fileStream.Seek(offset, SeekOrigin.Begin);

            byte[] buffer = new byte[4096];
            int bytesRead;
            while ((bytesRead = reader.Read(buffer, 0, buffer.Length)) > 0)
            {
                writer.Write(buffer, 0, bytesRead);
                offset += bytesRead;
                Console.WriteLine("Sent " + bytesRead + " bytes at offset " + offset);
            }
        }

        client.Dispose();
    }
}

注意，以上代码仅为示例，实际应用中需要考虑错误处理、超时、流关闭等情况。