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