mirror of
https://github.com/fergalmoran/DnsServer.git
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737 lines
31 KiB
C#
737 lines
31 KiB
C#
/*
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Technitium DNS Server
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Copyright (C) 2022 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.Dns.ResourceRecords;
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using DnsServerCore.Dns.Trees;
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using DnsServerCore.Dns.Zones;
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using System;
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using System.Collections.Generic;
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using System.Threading;
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using TechnitiumLibrary.Net.Dns;
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using TechnitiumLibrary.Net.Dns.EDnsOptions;
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using TechnitiumLibrary.Net.Dns.ResourceRecords;
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namespace DnsServerCore.Dns.ZoneManagers
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{
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public sealed class CacheZoneManager : DnsCache
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{
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#region variables
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public const uint FAILURE_RECORD_TTL = 60u;
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public const uint NEGATIVE_RECORD_TTL = 300u;
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public const uint MINIMUM_RECORD_TTL = 10u;
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public const uint MAXIMUM_RECORD_TTL = 7 * 24 * 60 * 60;
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public const uint SERVE_STALE_TTL = 3 * 24 * 60 * 60; //3 days serve stale ttl as per https://www.rfc-editor.org/rfc/rfc8767.html suggestion
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readonly DnsServer _dnsServer;
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readonly CacheZoneTree _root = new CacheZoneTree();
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long _maximumEntries;
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long _totalEntries;
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#endregion
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#region constructor
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public CacheZoneManager(DnsServer dnsServer)
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: base(FAILURE_RECORD_TTL, NEGATIVE_RECORD_TTL, MINIMUM_RECORD_TTL, MAXIMUM_RECORD_TTL, SERVE_STALE_TTL)
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{
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_dnsServer = dnsServer;
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}
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#endregion
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#region protected
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protected override void CacheRecords(IReadOnlyList<DnsResourceRecord> resourceRecords)
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{
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List<DnsResourceRecord> dnameRecords = null;
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//read and set glue records from base class; also collect any DNAME records found
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foreach (DnsResourceRecord resourceRecord in resourceRecords)
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{
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IReadOnlyList<DnsResourceRecord> glueRecords = GetGlueRecordsFrom(resourceRecord);
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IReadOnlyList<DnsResourceRecord> rrsigRecords = GetRRSIGRecordsFrom(resourceRecord);
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IReadOnlyList<DnsResourceRecord> nsecRecords = GetNSECRecordsFrom(resourceRecord);
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if ((glueRecords is not null) || (rrsigRecords is not null) || (nsecRecords is not null))
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{
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DnsResourceRecordInfo rrInfo = resourceRecord.GetRecordInfo();
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rrInfo.GlueRecords = glueRecords;
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rrInfo.RRSIGRecords = rrsigRecords;
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rrInfo.NSECRecords = nsecRecords;
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if (glueRecords is not null)
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{
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foreach (DnsResourceRecord glueRecord in glueRecords)
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{
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IReadOnlyList<DnsResourceRecord> glueRRSIGRecords = GetRRSIGRecordsFrom(glueRecord);
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if (glueRRSIGRecords is not null)
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glueRecord.GetRecordInfo().RRSIGRecords = glueRRSIGRecords;
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}
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}
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if (nsecRecords is not null)
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{
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foreach (DnsResourceRecord nsecRecord in nsecRecords)
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{
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IReadOnlyList<DnsResourceRecord> nsecRRSIGRecords = GetRRSIGRecordsFrom(nsecRecord);
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if (nsecRRSIGRecords is not null)
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nsecRecord.GetRecordInfo().RRSIGRecords = nsecRRSIGRecords;
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}
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}
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}
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if (resourceRecord.Type == DnsResourceRecordType.DNAME)
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{
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if (dnameRecords is null)
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dnameRecords = new List<DnsResourceRecord>(1);
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dnameRecords.Add(resourceRecord);
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}
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}
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if (resourceRecords.Count == 1)
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{
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DnsResourceRecord resourceRecord = resourceRecords[0];
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CacheZone zone = _root.GetOrAdd(resourceRecord.Name, delegate (string key)
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{
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return new CacheZone(resourceRecord.Name, 1);
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});
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if (zone.SetRecords(resourceRecord.Type, resourceRecords, _dnsServer.ServeStale))
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Interlocked.Increment(ref _totalEntries);
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}
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else
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{
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Dictionary<string, Dictionary<DnsResourceRecordType, List<DnsResourceRecord>>> groupedByDomainRecords = DnsResourceRecord.GroupRecords(resourceRecords);
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bool serveStale = _dnsServer.ServeStale;
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int addedEntries = 0;
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//add grouped records
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foreach (KeyValuePair<string, Dictionary<DnsResourceRecordType, List<DnsResourceRecord>>> groupedByTypeRecords in groupedByDomainRecords)
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{
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if (dnameRecords is not null)
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{
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bool foundSynthesizedCNAME = false;
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foreach (DnsResourceRecord dnameRecord in dnameRecords)
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{
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if (groupedByTypeRecords.Key.EndsWith("." + dnameRecord.Name, StringComparison.OrdinalIgnoreCase))
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{
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foundSynthesizedCNAME = true;
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break;
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}
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}
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if (foundSynthesizedCNAME)
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continue; //do not cache synthesized CNAME
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}
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CacheZone zone = _root.GetOrAdd(groupedByTypeRecords.Key, delegate (string key)
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{
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return new CacheZone(groupedByTypeRecords.Key, groupedByTypeRecords.Value.Count);
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});
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foreach (KeyValuePair<DnsResourceRecordType, List<DnsResourceRecord>> groupedRecords in groupedByTypeRecords.Value)
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{
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if (zone.SetRecords(groupedRecords.Key, groupedRecords.Value, serveStale))
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addedEntries++;
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}
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}
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if (addedEntries > 0)
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Interlocked.Add(ref _totalEntries, addedEntries);
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}
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}
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#endregion
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#region private
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private static IReadOnlyList<DnsResourceRecord> AddDSRecordsTo(CacheZone delegation, bool serveStale, IReadOnlyList<DnsResourceRecord> nsRecords)
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{
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IReadOnlyList<DnsResourceRecord> records = delegation.QueryRecords(DnsResourceRecordType.DS, serveStale, true);
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if ((records.Count > 0) && (records[0].Type == DnsResourceRecordType.DS))
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{
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List<DnsResourceRecord> newNSRecords = new List<DnsResourceRecord>(nsRecords.Count + records.Count);
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newNSRecords.AddRange(nsRecords);
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newNSRecords.AddRange(records);
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return newNSRecords;
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}
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//no DS records found check for NSEC records
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IReadOnlyList<DnsResourceRecord> nsecRecords = nsRecords[0].GetRecordInfo().NSECRecords;
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if (nsecRecords is not null)
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{
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List<DnsResourceRecord> newNSRecords = new List<DnsResourceRecord>(nsRecords.Count + nsecRecords.Count);
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newNSRecords.AddRange(nsRecords);
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newNSRecords.AddRange(nsecRecords);
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return newNSRecords;
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}
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//found nothing; return original NS records
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return nsRecords;
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}
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private void ResolveCNAME(DnsQuestionRecord question, DnsResourceRecord lastCNAME, bool serveStale, List<DnsResourceRecord> answerRecords)
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{
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int queryCount = 0;
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do
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{
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if (!_root.TryGet((lastCNAME.RDATA as DnsCNAMERecordData).Domain, out CacheZone cacheZone))
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break;
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IReadOnlyList<DnsResourceRecord> records = cacheZone.QueryRecords(question.Type, serveStale, true);
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if (records.Count < 1)
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break;
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answerRecords.AddRange(records);
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DnsResourceRecord lastRR = records[records.Count - 1];
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if (lastRR.Type != DnsResourceRecordType.CNAME)
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break;
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lastCNAME = lastRR;
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}
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while (++queryCount < DnsServer.MAX_CNAME_HOPS);
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}
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private bool DoDNAMESubstitution(DnsQuestionRecord question, IReadOnlyList<DnsResourceRecord> answer, bool serveStale, out IReadOnlyList<DnsResourceRecord> newAnswer)
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{
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DnsResourceRecord dnameRR = answer[0];
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string result = (dnameRR.RDATA as DnsDNAMERecordData).Substitute(question.Name, dnameRR.Name);
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if (DnsClient.IsDomainNameValid(result))
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{
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DnsResourceRecord cnameRR = new DnsResourceRecord(question.Name, DnsResourceRecordType.CNAME, question.Class, dnameRR.TtlValue, new DnsCNAMERecordData(result));
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List<DnsResourceRecord> list = new List<DnsResourceRecord>(5)
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{
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dnameRR,
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cnameRR
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};
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ResolveCNAME(question, cnameRR, serveStale, list);
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newAnswer = list;
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return true;
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}
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else
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{
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newAnswer = answer;
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return false;
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}
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}
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private IReadOnlyList<DnsResourceRecord> GetAdditionalRecords(IReadOnlyList<DnsResourceRecord> refRecords, bool serveStale, bool dnssecOk)
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{
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List<DnsResourceRecord> additionalRecords = new List<DnsResourceRecord>();
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foreach (DnsResourceRecord refRecord in refRecords)
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{
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switch (refRecord.Type)
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{
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case DnsResourceRecordType.NS:
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DnsNSRecordData nsRecord = refRecord.RDATA as DnsNSRecordData;
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if (nsRecord is not null)
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ResolveAdditionalRecords(refRecord, nsRecord.NameServer, serveStale, dnssecOk, additionalRecords);
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break;
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case DnsResourceRecordType.MX:
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DnsMXRecordData mxRecord = refRecord.RDATA as DnsMXRecordData;
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if (mxRecord is not null)
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ResolveAdditionalRecords(refRecord, mxRecord.Exchange, serveStale, dnssecOk, additionalRecords);
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break;
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case DnsResourceRecordType.SRV:
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DnsSRVRecordData srvRecord = refRecord.RDATA as DnsSRVRecordData;
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if (srvRecord is not null)
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ResolveAdditionalRecords(refRecord, srvRecord.Target, serveStale, dnssecOk, additionalRecords);
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break;
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}
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}
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return additionalRecords;
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}
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private void ResolveAdditionalRecords(DnsResourceRecord refRecord, string domain, bool serveStale, bool dnssecOk, List<DnsResourceRecord> additionalRecords)
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{
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IReadOnlyList<DnsResourceRecord> glueRecords = refRecord.GetGlueRecords();
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if (glueRecords.Count > 0)
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{
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bool added = false;
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foreach (DnsResourceRecord glueRecord in glueRecords)
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{
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if (!glueRecord.IsStale)
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{
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added = true;
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additionalRecords.Add(glueRecord);
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if (dnssecOk)
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{
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IReadOnlyList<DnsResourceRecord> rrsigRecords = glueRecord.GetRecordInfo().RRSIGRecords;
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if (rrsigRecords is not null)
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additionalRecords.AddRange(rrsigRecords);
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}
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}
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}
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if (added)
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return;
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}
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if (_root.TryGet(domain, out CacheZone cacheZone))
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{
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{
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IReadOnlyList<DnsResourceRecord> records = cacheZone.QueryRecords(DnsResourceRecordType.A, serveStale, true);
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if ((records.Count > 0) && (records[0].Type == DnsResourceRecordType.A))
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additionalRecords.AddRange(records);
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}
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{
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IReadOnlyList<DnsResourceRecord> records = cacheZone.QueryRecords(DnsResourceRecordType.AAAA, serveStale, true);
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if ((records.Count > 0) && (records[0].Type == DnsResourceRecordType.AAAA))
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additionalRecords.AddRange(records);
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}
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}
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}
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private int RemoveExpiredRecordsInternal(bool serveStale, long minimumEntriesToRemove)
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{
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int removedEntries = 0;
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foreach (CacheZone zone in _root)
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{
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removedEntries += zone.RemoveExpiredRecords(serveStale);
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if (zone.IsEmpty)
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_root.TryRemove(zone.Name, out _); //remove empty zone
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if ((minimumEntriesToRemove > 0) && (removedEntries >= minimumEntriesToRemove))
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break;
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}
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if (removedEntries > 0)
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{
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long totalEntries = Interlocked.Add(ref _totalEntries, -removedEntries);
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if (totalEntries < 0)
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Interlocked.Add(ref _totalEntries, -totalEntries);
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}
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return removedEntries;
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}
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private int RemoveLeastUsedRecordsInternal(DateTime cutoff, long minimumEntriesToRemove)
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{
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int removedEntries = 0;
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foreach (CacheZone zone in _root)
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{
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removedEntries += zone.RemoveLeastUsedRecords(cutoff);
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if (zone.IsEmpty)
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_root.TryRemove(zone.Name, out _); //remove empty zone
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if ((minimumEntriesToRemove > 0) && (removedEntries >= minimumEntriesToRemove))
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break;
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}
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if (removedEntries > 0)
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{
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long totalEntries = Interlocked.Add(ref _totalEntries, -removedEntries);
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if (totalEntries < 0)
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Interlocked.Add(ref _totalEntries, -totalEntries);
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}
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return removedEntries;
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}
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#endregion
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#region public
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public override void RemoveExpiredRecords()
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{
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bool serveStale = _dnsServer.ServeStale;
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//remove expired records/expired stale records
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RemoveExpiredRecordsInternal(serveStale, 0);
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if (_maximumEntries < 1)
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return; //cache limit feature disabled
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//find minimum entries to remove
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long minimumEntriesToRemove = _totalEntries - _maximumEntries;
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if (minimumEntriesToRemove < 1)
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return; //no need to remove
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//remove stale records if they exists
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if (serveStale)
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minimumEntriesToRemove -= RemoveExpiredRecordsInternal(false, minimumEntriesToRemove);
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if (minimumEntriesToRemove < 1)
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return; //task completed
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//remove least recently used records
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for (int seconds = 86400; seconds > 0; seconds /= 2)
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{
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DateTime cutoff = DateTime.UtcNow.AddSeconds(-seconds);
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minimumEntriesToRemove -= RemoveLeastUsedRecordsInternal(cutoff, minimumEntriesToRemove);
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if (minimumEntriesToRemove < 1)
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break; //task completed
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}
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}
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public override void Flush()
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{
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_root.Clear();
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long totalEntries = _totalEntries;
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totalEntries = Interlocked.Add(ref _totalEntries, -totalEntries);
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if (totalEntries < 0)
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Interlocked.Add(ref _totalEntries, -totalEntries);
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}
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public bool DeleteZone(string domain)
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{
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if (_root.TryRemoveTree(domain, out _, out int removedEntries))
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{
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if (removedEntries > 0)
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{
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long totalEntries = Interlocked.Add(ref _totalEntries, -removedEntries);
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if (totalEntries < 0)
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Interlocked.Add(ref _totalEntries, -totalEntries);
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}
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return true;
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}
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return false;
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}
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public void ListSubDomains(string domain, List<string> subDomains)
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{
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_root.ListSubDomains(domain, subDomains);
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}
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public void ListAllRecords(string domain, List<DnsResourceRecord> records)
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{
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if (_root.TryGet(domain, out CacheZone zone))
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zone.ListAllRecords(records);
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}
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public override DnsDatagram QueryClosestDelegation(DnsDatagram request)
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{
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_ = _root.FindZone(request.Question[0].Name, out _, out CacheZone delegation);
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if (delegation is not null)
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{
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//return closest name servers in delegation
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IReadOnlyList<DnsResourceRecord> closestAuthority = delegation.QueryRecords(DnsResourceRecordType.NS, false, true);
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if ((closestAuthority.Count > 0) && (closestAuthority[0].Type == DnsResourceRecordType.NS) && (closestAuthority[0].Name.Length > 0)) //dont trust root name servers from cache!
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{
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if (request.DnssecOk)
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closestAuthority = AddDSRecordsTo(delegation, false, closestAuthority);
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IReadOnlyList<DnsResourceRecord> additional = GetAdditionalRecords(closestAuthority, false, request.DnssecOk);
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return new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, DnsResponseCode.NoError, request.Question, null, closestAuthority, additional);
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}
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}
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//no cached delegation found
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return null;
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}
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public override DnsDatagram Query(DnsDatagram request, bool serveStaleAndResetExpiry = false, bool findClosestNameServers = false)
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{
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DnsQuestionRecord question = request.Question[0];
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CacheZone zone;
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CacheZone closest = null;
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CacheZone delegation = null;
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if (findClosestNameServers)
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{
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zone = _root.FindZone(question.Name, out closest, out delegation);
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}
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else
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{
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if (!_root.TryGet(question.Name, out zone))
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_ = _root.FindZone(question.Name, out closest, out _); //zone not found; attempt to find closest
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}
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if (zone is not null)
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{
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//zone found
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IReadOnlyList<DnsResourceRecord> answers = zone.QueryRecords(question.Type, serveStaleAndResetExpiry, false);
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if (answers.Count > 0)
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{
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//answer found in cache
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DnsResourceRecord firstRR = answers[0];
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if (firstRR.RDATA is DnsSpecialCacheRecord dnsSpecialCacheRecord)
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{
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IReadOnlyList<EDnsOption> specialOptions = null;
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if (serveStaleAndResetExpiry)
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{
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if (firstRR.IsStale)
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firstRR.ResetExpiry(30); //reset expiry by 30 seconds so that resolver tries again only after 30 seconds as per draft-ietf-dnsop-serve-stale-04
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if (dnsSpecialCacheRecord.Authority is not null)
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{
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foreach (DnsResourceRecord record in dnsSpecialCacheRecord.Authority)
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{
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if (record.IsStale)
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record.ResetExpiry(30); //reset expiry by 30 seconds so that resolver tries again only after 30 seconds as per draft-ietf-dnsop-serve-stale-04
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}
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}
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if (dnsSpecialCacheRecord.RCODE == DnsResponseCode.NxDomain)
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{
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List<EDnsOption> newOptions = new List<EDnsOption>(dnsSpecialCacheRecord.EDnsOptions.Count + 1);
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|
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newOptions.AddRange(dnsSpecialCacheRecord.EDnsOptions);
|
|
newOptions.Add(new EDnsOption(EDnsOptionCode.EXTENDED_DNS_ERROR, new EDnsExtendedDnsErrorOption(EDnsExtendedDnsErrorCode.StaleNxDomainAnswer, null)));
|
|
|
|
specialOptions = newOptions;
|
|
}
|
|
}
|
|
|
|
if (specialOptions is null)
|
|
specialOptions = dnsSpecialCacheRecord.EDnsOptions;
|
|
|
|
if (request.DnssecOk)
|
|
{
|
|
bool authenticData;
|
|
|
|
switch (dnsSpecialCacheRecord.Type)
|
|
{
|
|
case DnsSpecialCacheRecordType.NegativeCache:
|
|
authenticData = true;
|
|
break;
|
|
|
|
default:
|
|
authenticData = false;
|
|
break;
|
|
}
|
|
|
|
if (request.CheckingDisabled)
|
|
return new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, authenticData, request.CheckingDisabled, dnsSpecialCacheRecord.OriginalRCODE, request.Question, dnsSpecialCacheRecord.OriginalAnswer, dnsSpecialCacheRecord.OriginalAuthority, dnsSpecialCacheRecord.Additional, _dnsServer.UdpPayloadSize, EDnsHeaderFlags.DNSSEC_OK, specialOptions);
|
|
else
|
|
return new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, authenticData, request.CheckingDisabled, dnsSpecialCacheRecord.RCODE, request.Question, null, dnsSpecialCacheRecord.Authority, null, _dnsServer.UdpPayloadSize, EDnsHeaderFlags.DNSSEC_OK, specialOptions);
|
|
}
|
|
else
|
|
{
|
|
return new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, dnsSpecialCacheRecord.RCODE, request.Question, null, dnsSpecialCacheRecord.NoDnssecAuthority, null, request.EDNS is null ? ushort.MinValue : _dnsServer.UdpPayloadSize, EDnsHeaderFlags.None, specialOptions);
|
|
}
|
|
}
|
|
|
|
DnsResourceRecord lastRR = answers[answers.Count - 1];
|
|
if ((lastRR.Type != question.Type) && (lastRR.Type == DnsResourceRecordType.CNAME) && (question.Type != DnsResourceRecordType.ANY))
|
|
{
|
|
List<DnsResourceRecord> newAnswers = new List<DnsResourceRecord>(answers.Count + 3);
|
|
newAnswers.AddRange(answers);
|
|
|
|
ResolveCNAME(question, lastRR, serveStaleAndResetExpiry, newAnswers);
|
|
|
|
answers = newAnswers;
|
|
}
|
|
|
|
IReadOnlyList<DnsResourceRecord> authority = null;
|
|
EDnsHeaderFlags ednsFlags = EDnsHeaderFlags.None;
|
|
|
|
if (request.DnssecOk)
|
|
{
|
|
//DNSSEC enabled; insert RRSIG records
|
|
List<DnsResourceRecord> newAnswers = new List<DnsResourceRecord>(answers.Count * 2);
|
|
List<DnsResourceRecord> newAuthority = null;
|
|
|
|
foreach (DnsResourceRecord answer in answers)
|
|
{
|
|
newAnswers.Add(answer);
|
|
|
|
DnsResourceRecordInfo rrInfo = answer.GetRecordInfo();
|
|
|
|
IReadOnlyList<DnsResourceRecord> rrsigRecords = rrInfo.RRSIGRecords;
|
|
if (rrsigRecords is not null)
|
|
{
|
|
newAnswers.AddRange(rrsigRecords);
|
|
|
|
foreach (DnsResourceRecord rrsigRecord in rrsigRecords)
|
|
{
|
|
if (!DnsRRSIGRecordData.IsWildcard(rrsigRecord))
|
|
continue;
|
|
|
|
//add NSEC/NSEC3 for the wildcard proof
|
|
if (newAuthority is null)
|
|
newAuthority = new List<DnsResourceRecord>(2);
|
|
|
|
IReadOnlyList<DnsResourceRecord> nsecRecords = rrInfo.NSECRecords;
|
|
if (nsecRecords is not null)
|
|
{
|
|
foreach (DnsResourceRecord nsecRecord in nsecRecords)
|
|
{
|
|
newAuthority.Add(nsecRecord);
|
|
|
|
IReadOnlyList<DnsResourceRecord> nsecRRSIGRecords = nsecRecord.GetRecordInfo().RRSIGRecords;
|
|
if (nsecRRSIGRecords is not null)
|
|
newAuthority.AddRange(nsecRRSIGRecords);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
answers = newAnswers;
|
|
authority = newAuthority;
|
|
ednsFlags = EDnsHeaderFlags.DNSSEC_OK;
|
|
}
|
|
|
|
IReadOnlyList<DnsResourceRecord> additional = null;
|
|
|
|
switch (question.Type)
|
|
{
|
|
case DnsResourceRecordType.NS:
|
|
case DnsResourceRecordType.MX:
|
|
case DnsResourceRecordType.SRV:
|
|
additional = GetAdditionalRecords(answers, serveStaleAndResetExpiry, request.DnssecOk);
|
|
break;
|
|
}
|
|
|
|
EDnsOption[] options = null;
|
|
|
|
if (serveStaleAndResetExpiry)
|
|
{
|
|
foreach (DnsResourceRecord record in answers)
|
|
{
|
|
if (record.IsStale)
|
|
record.ResetExpiry(30); //reset expiry by 30 seconds so that resolver tries again only after 30 seconds as per draft-ietf-dnsop-serve-stale-04
|
|
}
|
|
|
|
if (additional is not null)
|
|
{
|
|
foreach (DnsResourceRecord record in additional)
|
|
{
|
|
if (record.IsStale)
|
|
record.ResetExpiry(30); //reset expiry by 30 seconds so that resolver tries again only after 30 seconds as per draft-ietf-dnsop-serve-stale-04
|
|
}
|
|
}
|
|
|
|
options = new EDnsOption[] { new EDnsOption(EDnsOptionCode.EXTENDED_DNS_ERROR, new EDnsExtendedDnsErrorOption(EDnsExtendedDnsErrorCode.StaleAnswer, null)) };
|
|
}
|
|
|
|
return new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, answers[0].DnssecStatus == DnssecStatus.Secure, request.CheckingDisabled, DnsResponseCode.NoError, request.Question, answers, authority, additional, request.EDNS is null ? ushort.MinValue : _dnsServer.UdpPayloadSize, ednsFlags, options);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
//zone not found
|
|
//check for DNAME in closest zone
|
|
if (closest is not null)
|
|
{
|
|
IReadOnlyList<DnsResourceRecord> answer = closest.QueryRecords(DnsResourceRecordType.DNAME, serveStaleAndResetExpiry, true);
|
|
if ((answer.Count > 0) && (answer[0].Type == DnsResourceRecordType.DNAME))
|
|
{
|
|
DnsResponseCode rCode;
|
|
|
|
if (DoDNAMESubstitution(question, answer, serveStaleAndResetExpiry, out answer))
|
|
rCode = DnsResponseCode.NoError;
|
|
else
|
|
rCode = DnsResponseCode.YXDomain;
|
|
|
|
return new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, answer[0].DnssecStatus == DnssecStatus.Secure, request.CheckingDisabled, rCode, request.Question, answer);
|
|
}
|
|
}
|
|
}
|
|
|
|
//no answer in cache
|
|
//check for closest delegation if any
|
|
if (findClosestNameServers && (delegation is not null))
|
|
{
|
|
//return closest name servers in delegation
|
|
if (question.Type == DnsResourceRecordType.DS)
|
|
{
|
|
//find parent delegation
|
|
string domain = AuthZoneManager.GetParentZone(question.Name);
|
|
if (domain is null)
|
|
return null; //dont find NS for root
|
|
|
|
_ = _root.FindZone(domain, out _, out delegation);
|
|
if (delegation is null)
|
|
return null; //no cached delegation found
|
|
}
|
|
|
|
IReadOnlyList<DnsResourceRecord> closestAuthority = delegation.QueryRecords(DnsResourceRecordType.NS, serveStaleAndResetExpiry, true);
|
|
if ((closestAuthority.Count > 0) && (closestAuthority[0].Type == DnsResourceRecordType.NS) && (closestAuthority[0].Name.Length > 0)) //dont trust root name servers from cache!
|
|
{
|
|
if (request.DnssecOk)
|
|
closestAuthority = AddDSRecordsTo(delegation, serveStaleAndResetExpiry, closestAuthority);
|
|
|
|
IReadOnlyList<DnsResourceRecord> additional = GetAdditionalRecords(closestAuthority, serveStaleAndResetExpiry, request.DnssecOk);
|
|
|
|
return new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, closestAuthority[0].DnssecStatus == DnssecStatus.Secure, request.CheckingDisabled, DnsResponseCode.NoError, request.Question, null, closestAuthority, additional);
|
|
}
|
|
}
|
|
|
|
//no cached delegation found
|
|
return null;
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region properties
|
|
|
|
public long MaximumEntries
|
|
{
|
|
get { return _maximumEntries; }
|
|
set
|
|
{
|
|
if (value < 0)
|
|
throw new ArgumentOutOfRangeException(nameof(MaximumEntries), "Invalid cache maximum entries value. Valid range is 0 and above.");
|
|
|
|
_maximumEntries = value;
|
|
}
|
|
}
|
|
|
|
public long TotalEntries
|
|
{ get { return _totalEntries; } }
|
|
|
|
#endregion
|
|
}
|
|
}
|