116 lines
4.0 KiB
C#
116 lines
4.0 KiB
C#
using DNS.Protocol;
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using FastGithub.Configuration;
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using Microsoft.Extensions.Logging;
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using System;
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using System.Net;
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using System.Net.Sockets;
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using System.Threading;
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using System.Threading.Tasks;
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namespace FastGithub.Dns
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{
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/// <summary>
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/// dns服务器
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/// </summary>
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sealed class DnsOverUdpServer : IDisposable
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{
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private readonly RequestResolver requestResolver;
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private readonly ILogger<DnsOverUdpServer> logger;
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private readonly Socket socket = new(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
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private readonly byte[] buffer = new byte[ushort.MaxValue];
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/// <summary>
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/// dns服务器
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/// </summary>
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/// <param name="requestResolver"></param>
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/// <param name="logger"></param>
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public DnsOverUdpServer(
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RequestResolver requestResolver,
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ILogger<DnsOverUdpServer> logger)
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{
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this.requestResolver = requestResolver;
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this.logger = logger;
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}
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/// <summary>
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/// 绑定地址和端口
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/// </summary>
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/// <param name="address"></param>
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/// <param name="port"></param>
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/// <returns></returns>
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public void Bind(IPAddress address, int port)
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{
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if (OperatingSystem.IsWindows())
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{
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UdpTable.KillPortOwner(port);
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}
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if (LocalMachine.CanListenUdp(port) == false)
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{
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throw new FastGithubException($"udp端口{port}已经被其它进程占用");
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}
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if (OperatingSystem.IsWindows())
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{
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const int SIO_UDP_CONNRESET = unchecked((int)0x9800000C);
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this.socket.IOControl(SIO_UDP_CONNRESET, new byte[4], new byte[4]);
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}
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this.socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
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this.socket.Bind(new IPEndPoint(address, port));
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}
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/// <summary>
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/// 监听和处理dns请求
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/// </summary>
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/// <param name="cancellationToken"></param>
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/// <returns></returns>
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public async Task HandleAsync(CancellationToken cancellationToken)
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{
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var remoteEndPoint = new IPEndPoint(IPAddress.Any, 0);
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while (cancellationToken.IsCancellationRequested == false)
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{
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try
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{
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var result = await this.socket.ReceiveFromAsync(this.buffer, SocketFlags.None, remoteEndPoint);
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var datas = new byte[result.ReceivedBytes];
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this.buffer.AsSpan(0, datas.Length).CopyTo(datas);
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this.HandleRequestAsync(datas, result.RemoteEndPoint, cancellationToken);
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}
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catch (SocketException ex) when (ex.SocketErrorCode == SocketError.OperationAborted)
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{
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break;
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}
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}
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}
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/// <summary>
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/// 处理dns请求
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/// </summary>
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/// <param name="datas"></param>
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/// <param name="remoteEndPoint"></param>
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/// <param name="cancellationToken"></param>
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private async void HandleRequestAsync(byte[] datas, EndPoint remoteEndPoint, CancellationToken cancellationToken)
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{
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try
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{
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var request = Request.FromArray(datas);
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var remoteEndPointRequest = new RemoteEndPointRequest(request, remoteEndPoint);
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var response = await this.requestResolver.Resolve(remoteEndPointRequest, cancellationToken);
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await this.socket.SendToAsync(response.ToArray(), SocketFlags.None, remoteEndPoint);
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}
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catch (Exception ex)
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{
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this.logger.LogWarning($"处理DNS异常：{ex.Message}");
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}
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}
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/// <summary>
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/// 释放资源
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/// </summary>
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public void Dispose()
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{
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this.socket.Dispose();
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}
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}
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}
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