132 lines
4.6 KiB
C#
132 lines
4.6 KiB
C#
using DNS.Protocol;
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using DNS.Protocol.ResourceRecords;
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using FastGithub.Configuration;
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using Microsoft.Extensions.Logging;
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using PacketDotNet;
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using System;
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using System.Linq;
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using System.Net;
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using System.Runtime.InteropServices;
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using System.Runtime.Versioning;
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using System.Threading;
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using WinDivertSharp;
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namespace FastGithub.Dns
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{
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/// <summary>
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/// dns投毒服务
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/// </summary>
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[SupportedOSPlatform("windows")]
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sealed class DnsPoisoningServer
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{
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const string DNS_FILTER = "udp.DstPort == 53";
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private readonly FastGithubConfig fastGithubConfig;
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private readonly ILogger<DnsPoisoningServer> logger;
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private readonly TimeSpan ttl = TimeSpan.FromSeconds(10d);
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/// <summary>
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/// 刷新DNS缓存
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/// </summary>
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[DllImport("dnsapi.dll", EntryPoint = "DnsFlushResolverCache", SetLastError = true)]
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private static extern void DnsFlushResolverCache();
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/// <summary>
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/// dns投毒后台服务
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/// </summary>
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/// <param name="fastGithubConfig"></param>
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/// <param name="logger"></param>
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public DnsPoisoningServer(
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FastGithubConfig fastGithubConfig,
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ILogger<DnsPoisoningServer> logger)
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{
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this.fastGithubConfig = fastGithubConfig;
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this.logger = logger;
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}
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/// <summary>
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/// DNS投毒
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/// </summary>
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/// <param name="cancellationToken"></param>
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public void DnsPoisoning(CancellationToken cancellationToken)
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{
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var handle = WinDivert.WinDivertOpen(DNS_FILTER, WinDivertLayer.Network, 0, WinDivertOpenFlags.None);
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if (handle == IntPtr.Zero)
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{
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return;
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}
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var packetLength = 0U;
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var packetBuffer = new byte[ushort.MaxValue];
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using var winDivertBuffer = new WinDivertBuffer(packetBuffer);
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var winDivertAddress = new WinDivertAddress();
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DnsFlushResolverCache();
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while (cancellationToken.IsCancellationRequested == false)
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{
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if (WinDivert.WinDivertRecv(handle, winDivertBuffer, ref winDivertAddress, ref packetLength))
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{
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try
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{
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this.ProcessDnsPacket(packetBuffer, ref packetLength);
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}
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catch (Exception ex)
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{
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this.logger.LogWarning(ex.Message);
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}
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WinDivert.WinDivertHelperCalcChecksums(winDivertBuffer, packetLength, ref winDivertAddress, WinDivertChecksumHelperParam.All);
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WinDivert.WinDivertSend(handle, winDivertBuffer, packetLength, ref winDivertAddress);
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}
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}
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WinDivert.WinDivertClose(handle);
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DnsFlushResolverCache();
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}
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/// <summary>
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/// 处理DNS数据包
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/// </summary>
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/// <param name="packetBuffer"></param>
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private void ProcessDnsPacket(byte[] packetBuffer, ref uint packetLength)
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{
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var packetData = packetBuffer.AsSpan(0, (int)packetLength).ToArray();
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var packet = Packet.ParsePacket(LinkLayers.Raw, packetData);
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var ipPacket = (IPPacket)packet.PayloadPacket;
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var udpPacket = (UdpPacket)ipPacket.PayloadPacket;
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var request = Request.FromArray(udpPacket.PayloadData);
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var question = request.Questions.FirstOrDefault();
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if (question == null || question.Type != RecordType.A)
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{
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return;
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}
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var domain = question.Name;
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if (this.fastGithubConfig.IsMatch(domain.ToString()) == false)
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{
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return;
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}
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// 反转ip
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var sourAddress = ipPacket.SourceAddress;
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ipPacket.SourceAddress = ipPacket.DestinationAddress;
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ipPacket.DestinationAddress = sourAddress;
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// 反转端口
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var sourPort = udpPacket.SourcePort;
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udpPacket.SourcePort = udpPacket.DestinationPort;
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udpPacket.DestinationPort = sourPort;
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// 设置dns响应
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var response = Response.FromRequest(request);
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var record = new IPAddressResourceRecord(domain, IPAddress.Loopback, this.ttl);
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response.AnswerRecords.Add(record);
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udpPacket.PayloadData = response.ToArray();
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// 修改数据内容和数据长度
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packet.Bytes.CopyTo(packetBuffer, 0);
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packetLength = (uint)packet.Bytes.Length;
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}
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}
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}
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