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Zone: serve stale querying support implemented. Query response record shuffeling implemented to allow load balancing across all IP addresses. Added check in non authoritative zone type to remove CNAME entry if different type of entry is added in the zone to prevent issue with serve stale.

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This commit is contained in:
Shreyas Zare
2019-03-30 17:01:44 +05:30
parent 873f5953be
commit 4049b8a486
1 changed files with 71 additions and 32 deletions
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103
DnsServerCore/Zone.cs
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@@ -43,6 +43,7 @@ namespace DnsServerCore
readonly ConcurrentDictionary<DnsResourceRecordType, DnsResourceRecord[]> _entries = new ConcurrentDictionary<DnsResourceRecordType, DnsResourceRecord[]>();
string _serverDomain;
uint _serveStaleTtl;
#endregion
@@ -96,7 +97,7 @@ namespace DnsServerCore
private static string[] ConvertDomainToPath(string domainName)
{
DnsDatagram.IsDomainNameValid(domainName, true);
DnsClient.IsDomainNameValid(domainName, true);
if (string.IsNullOrEmpty(domainName))
return new string[] { };
@@ -257,7 +258,7 @@ namespace DnsServerCore
}
}
private DnsResourceRecord[] QueryRecords(DnsResourceRecordType type, bool bypassCNAME)
private DnsResourceRecord[] QueryRecords(DnsResourceRecordType type, bool bypassCNAME, bool serveStale)
{
if (_authoritativeZone && (type == DnsResourceRecordType.ANY))
{
@@ -266,18 +267,25 @@ namespace DnsServerCore
foreach (KeyValuePair<DnsResourceRecordType, DnsResourceRecord[]> entry in _entries)
allRecords.AddRange(entry.Value);
return FilterExpiredDisabledRecords(allRecords.ToArray());
return FilterExpiredDisabledRecords(allRecords.ToArray(), serveStale);
}
if (!bypassCNAME && _entries.TryGetValue(DnsResourceRecordType.CNAME, out DnsResourceRecord[] existingCNAMERecords))
{
DnsResourceRecord[] records = FilterExpiredDisabledRecords(existingCNAMERecords);
DnsResourceRecord[] records = FilterExpiredDisabledRecords(existingCNAMERecords, serveStale);
if (records != null)
return records;
}
if (_entries.TryGetValue(type, out DnsResourceRecord[] existingRecords))
return FilterExpiredDisabledRecords(existingRecords);
{
DnsResourceRecord[] records = FilterExpiredDisabledRecords(existingRecords, serveStale);
if (records != null)
DnsClient.ShuffleArray(records); //shuffle records to allow load balancing
return records;
}
return null;
}
@@ -309,7 +317,7 @@ namespace DnsServerCore
private void ListAuthoritativeZones(List<Zone> zones)
{
DnsResourceRecord[] soa = QueryRecords(DnsResourceRecordType.SOA, true);
DnsResourceRecord[] soa = QueryRecords(DnsResourceRecordType.SOA, true, false);
if (soa != null)
zones.Add(this);
@@ -323,6 +331,25 @@ namespace DnsServerCore
{
return records;
});
if (!_authoritativeZone)
{
//this is only applicable for cache zone
switch (type)
{
case DnsResourceRecordType.CNAME:
case DnsResourceRecordType.SOA:
case DnsResourceRecordType.NS:
//do nothing
break;
default:
//remove old CNAME entry since current new entry type overlaps any existing CNAME entry in cache
//keeping both entries will create issue with serve stale implementation since stale CNAME entry will be always returned
_entries.TryRemove(DnsResourceRecordType.CNAME, out DnsResourceRecord[] existingValues);
break;
}
}
}
private void AddRecord(DnsResourceRecord record)
@@ -400,13 +427,16 @@ namespace DnsServerCore
DeleteEmptyParentZones(this);
}
private DnsResourceRecord[] FilterExpiredDisabledRecords(DnsResourceRecord[] records)
private DnsResourceRecord[] FilterExpiredDisabledRecords(DnsResourceRecord[] records, bool serveStale)
{
if (records.Length == 1)
{
if (records[0].TTLValue < 1)
if (!serveStale && records[0].IsStale)
return null;
if (records[0].TTLValue < 1u)
return null; //ttl expired
DnsResourceRecordInfo rrInfo = records[0].Tag as DnsResourceRecordInfo;
if ((rrInfo != null) && rrInfo.Disabled)
return null;
@@ -418,9 +448,12 @@ namespace DnsServerCore
foreach (DnsResourceRecord record in records)
{
if (record.TTLValue < 1)
if (!serveStale && record.IsStale)
continue;
if (record.TTLValue < 1u)
continue; //ttl expired
DnsResourceRecordInfo rrInfo = record.Tag as DnsResourceRecordInfo;
if ((rrInfo != null) && rrInfo.Disabled)
continue;
@@ -461,14 +494,14 @@ namespace DnsServerCore
return currentZone;
}
private DnsResourceRecord[] QueryClosestCachedNameServers()
private DnsResourceRecord[] QueryClosestCachedNameServers(bool serveStale)
{
Zone currentZone = this;
DnsResourceRecord[] nsRecords = null;
while (currentZone != null)
{
nsRecords = currentZone.QueryRecords(DnsResourceRecordType.NS, true);
nsRecords = currentZone.QueryRecords(DnsResourceRecordType.NS, true, serveStale);
if ((nsRecords != null) && (nsRecords.Length > 0) && (nsRecords[0].RDATA is DnsNSRecord))
return nsRecords;
@@ -485,11 +518,11 @@ namespace DnsServerCore
while (currentZone != null)
{
nsRecords = currentZone.QueryRecords(DnsResourceRecordType.SOA, true);
nsRecords = currentZone.QueryRecords(DnsResourceRecordType.SOA, true, false);
if ((nsRecords != null) && (nsRecords.Length > 0) && (nsRecords[0].RDATA as DnsSOARecord).MasterNameServer.Equals(rootZoneServerDomain, StringComparison.CurrentCultureIgnoreCase))
return nsRecords;
nsRecords = currentZone.QueryRecords(DnsResourceRecordType.NS, true);
nsRecords = currentZone.QueryRecords(DnsResourceRecordType.NS, true, false);
if ((nsRecords != null) && (nsRecords.Length > 0))
return nsRecords;
@@ -508,7 +541,7 @@ namespace DnsServerCore
{
if (currentZone._entries.ContainsKey(DnsResourceRecordType.SOA))
{
nsRecords = currentZone.QueryRecords(DnsResourceRecordType.NS, true);
nsRecords = currentZone.QueryRecords(DnsResourceRecordType.NS, true, false);
if ((nsRecords != null) && (nsRecords.Length > 0))
return nsRecords;
@@ -521,7 +554,7 @@ namespace DnsServerCore
return null;
}
private static DnsResourceRecord[] QueryGlueRecords(Zone rootZone, DnsResourceRecord[] nsRecords)
private static DnsResourceRecord[] QueryGlueRecords(Zone rootZone, DnsResourceRecord[] nsRecords, bool serveStale)
{
List<DnsResourceRecord> glueRecords = new List<DnsResourceRecord>();
@@ -535,13 +568,13 @@ namespace DnsServerCore
if ((zone != null) && !zone._disabled)
{
{
DnsResourceRecord[] records = zone.QueryRecords(DnsResourceRecordType.A, true);
DnsResourceRecord[] records = zone.QueryRecords(DnsResourceRecordType.A, true, serveStale);
if ((records != null) && (records.Length > 0))
glueRecords.AddRange(records);
}
{
DnsResourceRecord[] records = zone.QueryRecords(DnsResourceRecordType.AAAA, true);
DnsResourceRecord[] records = zone.QueryRecords(DnsResourceRecordType.AAAA, true, serveStale);
if ((records != null) && (records.Length > 0))
glueRecords.AddRange(records);
}
@@ -573,7 +606,7 @@ namespace DnsServerCore
if (DomainEquals(closestZone._zoneName, domain))
{
//zone found
DnsResourceRecord[] records = closestZone.QueryRecords(question.Type, false);
DnsResourceRecord[] records = closestZone.QueryRecords(question.Type, false, false);
if (records == null)
{
//record type not found
@@ -608,7 +641,7 @@ namespace DnsServerCore
}
else
{
additional = QueryGlueRecords(rootZone, closestAuthoritativeNameServers);
additional = QueryGlueRecords(rootZone, closestAuthoritativeNameServers, false);
}
return new DnsDatagram(new DnsHeader(request.Header.Identifier, true, DnsOpcode.StandardQuery, true, false, request.Header.RecursionDesired, false, false, false, DnsResponseCode.NoError, 1, (ushort)records.Length, (ushort)closestAuthoritativeNameServers.Length, (ushort)additional.Length), request.Question, records, closestAuthoritativeNameServers, additional);
@@ -623,13 +656,13 @@ namespace DnsServerCore
else
{
//zone is delegated
DnsResourceRecord[] additional = QueryGlueRecords(rootZone, closestAuthority);
DnsResourceRecord[] additional = QueryGlueRecords(rootZone, closestAuthority, false);
return new DnsDatagram(new DnsHeader(request.Header.Identifier, true, DnsOpcode.StandardQuery, false, false, request.Header.RecursionDesired, false, false, false, DnsResponseCode.NoError, 1, 0, (ushort)closestAuthority.Length, (ushort)additional.Length), request.Question, new DnsResourceRecord[] { }, closestAuthority, additional);
}
}
private static DnsDatagram QueryCache(Zone rootZone, DnsDatagram request)
private static DnsDatagram QueryCache(Zone rootZone, DnsDatagram request, bool serveStale)
{
DnsQuestionRecord question = request.Question[0];
string domain = question.Name.ToLower();
@@ -638,7 +671,7 @@ namespace DnsServerCore
if (closestZone._zoneName.Equals(domain))
{
DnsResourceRecord[] records = closestZone.QueryRecords(question.Type, false);
DnsResourceRecord[] records = closestZone.QueryRecords(question.Type, false, serveStale);
if (records != null)
{
if (records[0].RDATA is DnsEmptyRecord)
@@ -667,10 +700,10 @@ namespace DnsServerCore
}
}
DnsResourceRecord[] nameServers = closestZone.QueryClosestCachedNameServers();
DnsResourceRecord[] nameServers = closestZone.QueryClosestCachedNameServers(serveStale);
if (nameServers != null)
{
DnsResourceRecord[] additional = QueryGlueRecords(rootZone, nameServers);
DnsResourceRecord[] additional = QueryGlueRecords(rootZone, nameServers, serveStale);
return new DnsDatagram(new DnsHeader(request.Header.Identifier, true, DnsOpcode.StandardQuery, false, false, request.Header.RecursionDesired, true, false, false, DnsResponseCode.NoError, 1, 0, (ushort)nameServers.Length, (ushort)additional.Length), request.Question, new DnsResourceRecord[] { }, nameServers, additional);
}
@@ -718,12 +751,12 @@ namespace DnsServerCore
return groupedByDomainRecords;
}
internal DnsDatagram Query(DnsDatagram request)
internal DnsDatagram Query(DnsDatagram request, bool serveStale = false)
{
if (_authoritativeZone)
return QueryAuthoritative(this, request);
return QueryCache(this, request);
return QueryCache(this, request, serveStale);
}
internal void CacheResponse(DnsDatagram response)
@@ -750,7 +783,7 @@ namespace DnsServerCore
ttl = authority.TTLValue;
DnsResourceRecord record = new DnsResourceRecord(question.Name, question.Type, DnsClass.IN, ttl, new DnsNXRecord(authority));
record.SetExpiry();
record.SetExpiry(_serveStaleTtl);
CreateZone(this, question.Name).SetRecords(question.Type, new DnsResourceRecord[] { record });
}
@@ -777,7 +810,7 @@ namespace DnsServerCore
ttl = authority.TTLValue;
DnsResourceRecord record = new DnsResourceRecord(question.Name, question.Type, DnsClass.IN, ttl, new DnsEmptyRecord(authority));
record.SetExpiry();
record.SetExpiry(_serveStaleTtl);
CreateZone(this, question.Name).SetRecords(question.Type, new DnsResourceRecord[] { record });
}
@@ -792,7 +825,7 @@ namespace DnsServerCore
{
//empty response from authority name server
DnsResourceRecord record = new DnsResourceRecord(question.Name, question.Type, DnsClass.IN, DEFAULT_RECORD_TTL, new DnsEmptyRecord(null));
record.SetExpiry();
record.SetExpiry(_serveStaleTtl);
CreateZone(this, question.Name).SetRecords(question.Type, new DnsResourceRecord[] { record });
break;
@@ -807,7 +840,7 @@ namespace DnsServerCore
foreach (DnsQuestionRecord question in response.Question)
{
DnsResourceRecord record = new DnsResourceRecord(question.Name, question.Type, DnsClass.IN, DEFAULT_RECORD_TTL, new DnsEmptyRecord(null));
record.SetExpiry();
record.SetExpiry(_serveStaleTtl);
CreateZone(this, question.Name).SetRecords(question.Type, new DnsResourceRecord[] { record });
}
@@ -826,7 +859,7 @@ namespace DnsServerCore
//set expiry for cached records
foreach (DnsResourceRecord record in allRecords)
record.SetExpiry();
record.SetExpiry(_serveStaleTtl);
SetRecords(allRecords);
@@ -842,7 +875,7 @@ namespace DnsServerCore
}
DnsResourceRecord anyRR = new DnsResourceRecord(response.Question[0].Name, DnsResourceRecordType.ANY, DnsClass.IN, ttl, new DnsANYRecord(response.Answer));
anyRR.SetExpiry();
anyRR.SetExpiry(_serveStaleTtl);
CreateZone(this, response.Question[0].Name).SetRecords(DnsResourceRecordType.ANY, new DnsResourceRecord[] { anyRR });
}
@@ -1034,6 +1067,12 @@ namespace DnsServerCore
set { _serverDomain = value; }
}
public uint ServeStaleTtl
{
get { return _serveStaleTtl; }
set { _serveStaleTtl = value; }
}
#endregion
public class ZoneInfo : IComparable<ZoneInfo>