mirror of
https://github.com/fergalmoran/DnsServer.git
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119 lines
4.1 KiB
C#
119 lines
4.1 KiB
C#
/*
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Technitium DNS Server
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Copyright (C) 2021 Shreyas Zare (shreyas@technitium.com)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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using DnsServerCore.ApplicationCommon;
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using Newtonsoft.Json;
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using System;
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using System.Collections.Generic;
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using System.Net;
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using System.Threading.Tasks;
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using TechnitiumLibrary.Net;
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using TechnitiumLibrary.Net.Dns;
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using TechnitiumLibrary.Net.Dns.ResourceRecords;
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namespace SplitHorizon
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{
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public class SimpleCNAME : IDnsAppRecordRequestHandler
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{
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#region IDisposable
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public void Dispose()
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{
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//do nothing
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}
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#endregion
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#region public
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public Task InitializeAsync(IDnsServer dnsServer, string config)
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{
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//no config needed
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return Task.CompletedTask;
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}
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public Task<DnsDatagram> ProcessRequestAsync(DnsDatagram request, IPEndPoint remoteEP, DnsTransportProtocol protocol, bool isRecursionAllowed, string zoneName, uint appRecordTtl, string appRecordData)
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{
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dynamic jsonAppRecordData = JsonConvert.DeserializeObject(appRecordData);
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dynamic jsonCname = null;
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foreach (dynamic jsonProperty in jsonAppRecordData)
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{
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string name = jsonProperty.Name;
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if ((name == "public") || (name == "private"))
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continue;
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NetworkAddress networkAddress = NetworkAddress.Parse(name);
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if (networkAddress.Contains(remoteEP.Address))
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{
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jsonCname = jsonProperty.Value;
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break;
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}
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}
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if (jsonCname is null)
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{
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if (NetUtilities.IsPrivateIP(remoteEP.Address))
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jsonCname = jsonAppRecordData.@private;
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else
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jsonCname = jsonAppRecordData.@public;
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if (jsonCname is null)
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return Task.FromResult<DnsDatagram>(null);
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}
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string cname = jsonCname.Value;
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if (string.IsNullOrEmpty(cname))
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return Task.FromResult<DnsDatagram>(null);
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DnsQuestionRecord question = request.Question[0];
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IReadOnlyList<DnsResourceRecord> answers;
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if (question.Name.Equals(zoneName, StringComparison.OrdinalIgnoreCase)) //check for zone apex
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answers = new DnsResourceRecord[] { new DnsResourceRecord(question.Name, DnsResourceRecordType.ANAME, DnsClass.IN, appRecordTtl, new DnsANAMERecord(cname)) }; //use ANAME
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else
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answers = new DnsResourceRecord[] { new DnsResourceRecord(question.Name, DnsResourceRecordType.CNAME, DnsClass.IN, appRecordTtl, new DnsCNAMERecord(cname)) };
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return Task.FromResult(new DnsDatagram(request.Identifier, true, request.OPCODE, true, false, request.RecursionDesired, isRecursionAllowed, false, false, DnsResponseCode.NoError, request.Question, answers));
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}
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#endregion
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#region properties
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public string Description
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{ get { return "Returns different CNAME record for clients querying over public, private, or other specified networks. Note that the app will return ANAME record for an APP record at zone apex."; } }
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public string ApplicationRecordDataTemplate
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{
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get
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{
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return @"{
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""public"": ""api.example.com"",
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""private"": ""api.example.corp"",
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""10.0.0.0/8"": ""api.intranet.example.corp""
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}";
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}
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}
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#endregion
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}
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}
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