|
|
@@ -0,0 +1,117 @@
|
|
|
+using System;
|
|
|
+using System.Collections.Generic;
|
|
|
+using System.IO;
|
|
|
+using System.Linq;
|
|
|
+using System.Net;
|
|
|
+using System.Net.Sockets;
|
|
|
+using System.Runtime.InteropServices;
|
|
|
+using System.Text;
|
|
|
+
|
|
|
+namespace DnsForwarder
|
|
|
+{
|
|
|
+ internal class Program
|
|
|
+ {
|
|
|
+ private static string DefaultServer;
|
|
|
+ private static string ChinaServer;
|
|
|
+ private static Dictionary<string, string> ChinaList;
|
|
|
+
|
|
|
+ private static void Main(string[] args)
|
|
|
+ {
|
|
|
+ if (args.Length != 3)
|
|
|
+ {
|
|
|
+ Console.WriteLine("<default dns server ip> <china dns server ip> <path to dnsmasq-china-list file>");
|
|
|
+ Environment.Exit(-1);
|
|
|
+ return;
|
|
|
+ }
|
|
|
+
|
|
|
+ Console.WriteLine("Starting...");
|
|
|
+ Console.WriteLine($"Default Server:{DefaultServer = args[0]}");
|
|
|
+ Console.WriteLine($"China DNS Server:{ChinaServer = args[1]}");
|
|
|
+ Console.WriteLine($"dnsmasq-china-list file:{args[2]}");
|
|
|
+
|
|
|
+ Console.WriteLine("Loading list file...");
|
|
|
+ ChinaList = LoadListFile(args[2]).ToDictionary(p => p[0], p => p[1]);
|
|
|
+
|
|
|
+ Console.WriteLine("OK. Listing...");
|
|
|
+
|
|
|
+ var listen = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
|
|
|
+ listen.Bind(new IPEndPoint(IPAddress.Any, 53));
|
|
|
+
|
|
|
+ while (true)
|
|
|
+ {
|
|
|
+ EndPoint inEp = new IPEndPoint(IPAddress.Any, 0);
|
|
|
+ var buf = new byte[1500];
|
|
|
+ var count = listen.ReceiveFrom(buf, 0, buf.Length, SocketFlags.None, ref inEp);
|
|
|
+ var domain = ExtractDomainName(buf, count);
|
|
|
+
|
|
|
+ var target = MatchServer(domain);
|
|
|
+
|
|
|
+ Console.WriteLine($"{DateTime.Now:yyyyMMdd HH:mm:ss} {inEp} [{target}]\t{domain}");
|
|
|
+
|
|
|
+ listen.SendTo(GetDnsResponse(buf, count, target), inEp);
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ private static string ExtractDomainName(byte[] buf, int count)
|
|
|
+ {
|
|
|
+ var lst = new List<byte[]>();
|
|
|
+
|
|
|
+ var ptr = 12;
|
|
|
+ while (buf[ptr] != 0)
|
|
|
+ {
|
|
|
+ ptr += buf[ptr] + 1;
|
|
|
+ }
|
|
|
+
|
|
|
+ var bufDomain = new byte[ptr - 12];
|
|
|
+ Array.Copy(buf, 12, bufDomain, 0, bufDomain.Length);
|
|
|
+
|
|
|
+ //dot fill
|
|
|
+ ptr = 0;
|
|
|
+ while (ptr < bufDomain.Length)
|
|
|
+ {
|
|
|
+ var b = bufDomain[ptr];
|
|
|
+ bufDomain[ptr] = (byte)'.';
|
|
|
+ ptr += b + 1;
|
|
|
+ }
|
|
|
+
|
|
|
+ return Encoding.ASCII.GetString(bufDomain, 1, bufDomain.Length - 1);
|
|
|
+ }
|
|
|
+
|
|
|
+ private static byte[] GetDnsResponse(byte[] buf, int count, string host, int port = 53)
|
|
|
+ {
|
|
|
+ using var to = new UdpClient();
|
|
|
+ to.Connect(host, 53);
|
|
|
+ to.Send(buf, count);
|
|
|
+ IPEndPoint outEp = null;
|
|
|
+ return to.Receive(ref outEp);
|
|
|
+ }
|
|
|
+
|
|
|
+ private static string MatchServer(string domain)
|
|
|
+ {
|
|
|
+ var lower = domain.ToLower();
|
|
|
+ if (lower.EndsWith(".cn")) return ChinaServer;
|
|
|
+
|
|
|
+ var parts = lower.Split('.').Reverse().ToArray();
|
|
|
+
|
|
|
+ for (int i = parts.Length - 1; i >= 0; i--)
|
|
|
+ {
|
|
|
+ var d = string.Join(".", parts.Take(i + 1).Reverse());
|
|
|
+ if (ChinaList.TryGetValue(d, out var tar)) return tar;
|
|
|
+ }
|
|
|
+
|
|
|
+ return DefaultServer;
|
|
|
+ }
|
|
|
+
|
|
|
+ private static string[][] LoadListFile(string path)
|
|
|
+ {
|
|
|
+ var lines = File.ReadAllLines(path);
|
|
|
+ var items = lines.Select(p =>
|
|
|
+ {
|
|
|
+ if (p.StartsWith("#")) return null;
|
|
|
+ var parts = p.Split('/');
|
|
|
+ return new[] { parts[1], parts[2] };
|
|
|
+ }).Where(p => p != null).ToArray();
|
|
|
+ return items;
|
|
|
+ }
|
|
|
+ }
|
|
|
+}
|
HOME