fergalmoran/DnsServer
1
0
Fork 0
mirror of https://github.com/fergalmoran/DnsServer.git synced 2026-04-05 04:09:28 +00:00
Code Issues Packages Projects Releases Wiki Activity

CacheZoneManager: added support for configuring serve stale answer and reset ttl. Updated Query() to split serve stale and reset expiry features.

Browse Source
This commit is contained in:
Shreyas Zare
2024-05-19 15:05:41 +05:30
parent f0c24092fc
commit 5b14987a2e
1 changed files with 52 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

94
DnsServerCore/Dns/ZoneManagers/CacheZoneManager.cs
View File

@@ -41,11 +41,17 @@ namespace DnsServerCore.Dns.ZoneManagers
public const uint MINIMUM_RECORD_TTL = 10u;
public const uint MAXIMUM_RECORD_TTL = 7 * 24 * 60 * 60;
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
public const uint SERVE_STALE_ANSWER_TTL = 30; //as per https://www.rfc-editor.org/rfc/rfc8767.html suggestion
public const uint SERVE_STALE_RESET_TTL = 30; //as per https://www.rfc-editor.org/rfc/rfc8767.html suggestion
const uint SERVE_STALE_MIN_RESET_TTL = 10;
const uint SERVE_STALE_MAX_RESET_TTL = 900;
readonly DnsServer _dnsServer;
readonly CacheZoneTree _root = new CacheZoneTree();
uint _serveStaleResetTtl = SERVE_STALE_RESET_TTL;
long _maximumEntries;
long _totalEntries;
@@ -54,7 +60,7 @@ namespace DnsServerCore.Dns.ZoneManagers
#region constructor
public CacheZoneManager(DnsServer dnsServer)
: base(FAILURE_RECORD_TTL, NEGATIVE_RECORD_TTL, MINIMUM_RECORD_TTL, MAXIMUM_RECORD_TTL, SERVE_STALE_TTL)
: base(FAILURE_RECORD_TTL, NEGATIVE_RECORD_TTL, MINIMUM_RECORD_TTL, MAXIMUM_RECORD_TTL, SERVE_STALE_TTL, SERVE_STALE_ANSWER_TTL)
{
_dnsServer = dnsServer;
}
@@ -687,7 +693,7 @@ namespace DnsServerCore.Dns.ZoneManagers
return null;
}
public override DnsDatagram Query(DnsDatagram request, bool serveStaleAndResetExpiry = false, bool findClosestNameServers = false)
public override DnsDatagram Query(DnsDatagram request, bool serveStale = false, bool findClosestNameServers = false, bool resetExpiry = false)
{
DnsQuestionRecord question = request.Question[0];
@@ -721,7 +727,7 @@ namespace DnsServerCore.Dns.ZoneManagers
if (zone is not null)
{
//zone found
IReadOnlyList<DnsResourceRecord> answer = zone.QueryRecords(question.Type, serveStaleAndResetExpiry, false, eDnsClientSubnet, advancedForwardingClientSubnet);
IReadOnlyList<DnsResourceRecord> answer = zone.QueryRecords(question.Type, serveStale, false, eDnsClientSubnet, advancedForwardingClientSubnet);
if (answer.Count > 0)
{
//answer found in cache
@@ -738,24 +744,24 @@ namespace DnsServerCore.Dns.ZoneManagers
}
}
if (serveStaleAndResetExpiry)
if (resetExpiry)
{
if (firstRR.IsStale)
firstRR.ResetExpiry(30); //reset expiry by 30 seconds so that resolver tries again only after 30 seconds as per RFC 8767
firstRR.ResetExpiry(_serveStaleResetTtl); //reset expiry by 30 seconds so that resolver tries again only after 30 seconds as per RFC 8767
if (dnsSpecialCacheRecord.Authority is not null)
{
foreach (DnsResourceRecord record in dnsSpecialCacheRecord.Authority)
{
if (record.IsStale)
record.ResetExpiry(30); //reset expiry by 30 seconds so that resolver tries again only after 30 seconds as per RFC 8767
record.ResetExpiry(_serveStaleResetTtl); //reset expiry by 30 seconds so that resolver tries again only after 30 seconds as per RFC 8767
}
}
}
IReadOnlyList<EDnsOption> specialOptions;
if (firstRR.WasExpiryReset)
if (firstRR.WasExpiryReset || firstRR.IsStale)
{
List<EDnsOption> newOptions = new List<EDnsOption>(dnsSpecialCacheRecord.EDnsOptions.Count + 1);
@@ -832,7 +838,7 @@ namespace DnsServerCore.Dns.ZoneManagers
List<DnsResourceRecord> newAnswers = new List<DnsResourceRecord>(answer.Count + 3);
newAnswers.AddRange(answer);
ResolveCNAME(question, lastRR, serveStaleAndResetExpiry, eDnsClientSubnet, advancedForwardingClientSubnet, newAnswers);
ResolveCNAME(question, lastRR, serveStale, eDnsClientSubnet, advancedForwardingClientSubnet, newAnswers);
answer = newAnswers;
}
@@ -864,18 +870,16 @@ namespace DnsServerCore.Dns.ZoneManagers
case DnsResourceRecordType.SRV:
case DnsResourceRecordType.SVCB:
case DnsResourceRecordType.HTTPS:
additional = GetAdditionalRecords(answer, serveStaleAndResetExpiry, dnssecOk, eDnsClientSubnet, advancedForwardingClientSubnet);
additional = GetAdditionalRecords(answer, serveStale, dnssecOk, eDnsClientSubnet, advancedForwardingClientSubnet);
break;
}
IReadOnlyList<EDnsOption> options = null;
if (serveStaleAndResetExpiry)
if (resetExpiry)
{
foreach (DnsResourceRecord record in answer)
{
if (record.IsStale)
record.ResetExpiry(30); //reset expiry by 30 seconds so that resolver tries again only after 30 seconds as per RFC 8767
record.ResetExpiry(_serveStaleResetTtl); //reset expiry by 30 seconds so that resolver tries again only after 30 seconds as per RFC 8767
}
if (additional is not null)
@@ -883,21 +887,19 @@ namespace DnsServerCore.Dns.ZoneManagers
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 RFC 8767
record.ResetExpiry(_serveStaleResetTtl); //reset expiry by 30 seconds so that resolver tries again only after 30 seconds as per RFC 8767
}
}
options = new EDnsOption[] { new EDnsOption(EDnsOptionCode.EXTENDED_DNS_ERROR, new EDnsExtendedDnsErrorOptionData(EDnsExtendedDnsErrorCode.StaleAnswer, null)) };
}
else
IReadOnlyList<EDnsOption> options = null;
foreach (DnsResourceRecord record in answer)
{
foreach (DnsResourceRecord record in answer)
if (record.WasExpiryReset || record.IsStale)
{
if (record.WasExpiryReset)
{
options = new EDnsOption[] { new EDnsOption(EDnsOptionCode.EXTENDED_DNS_ERROR, new EDnsExtendedDnsErrorOptionData(EDnsExtendedDnsErrorCode.StaleAnswer, null)) };
break;
}
options = [new EDnsOption(EDnsOptionCode.EXTENDED_DNS_ERROR, new EDnsExtendedDnsErrorOptionData(EDnsExtendedDnsErrorCode.StaleAnswer, null))];
break;
}
}
@@ -948,12 +950,12 @@ namespace DnsServerCore.Dns.ZoneManagers
//check for DNAME in closest zone
if (closest is not null)
{
IReadOnlyList<DnsResourceRecord> answer = closest.QueryRecords(DnsResourceRecordType.DNAME, serveStaleAndResetExpiry, true, eDnsClientSubnet, advancedForwardingClientSubnet);
IReadOnlyList<DnsResourceRecord> answer = closest.QueryRecords(DnsResourceRecordType.DNAME, serveStale, true, eDnsClientSubnet, advancedForwardingClientSubnet);
if ((answer.Count > 0) && (answer[0].Type == DnsResourceRecordType.DNAME))
{
DnsResponseCode rCode;
if (DoDNAMESubstitution(question, answer, serveStaleAndResetExpiry, eDnsClientSubnet, advancedForwardingClientSubnet, out answer))
if (DoDNAMESubstitution(question, answer, serveStale, eDnsClientSubnet, advancedForwardingClientSubnet, out answer))
rCode = DnsResponseCode.NoError;
else
rCode = DnsResponseCode.YXDomain;
@@ -976,27 +978,23 @@ namespace DnsServerCore.Dns.ZoneManagers
ednsFlags = EDnsHeaderFlags.DNSSEC_OK;
}
EDnsOption[] options = null;
if (serveStaleAndResetExpiry)
if (resetExpiry)
{
foreach (DnsResourceRecord record in answer)
{
if (record.IsStale)
record.ResetExpiry(30); //reset expiry by 30 seconds so that resolver tries again only after 30 seconds as per RFC 8767
record.ResetExpiry(_serveStaleResetTtl); //reset expiry by 30 seconds so that resolver tries again only after 30 seconds as per RFC 8767
}
options = new EDnsOption[] { new EDnsOption(EDnsOptionCode.EXTENDED_DNS_ERROR, new EDnsExtendedDnsErrorOptionData(EDnsExtendedDnsErrorCode.StaleAnswer, null)) };
}
else
EDnsOption[] options = null;
foreach (DnsResourceRecord record in answer)
{
foreach (DnsResourceRecord record in answer)
if (record.WasExpiryReset || record.IsStale)
{
if (record.WasExpiryReset)
{
options = new EDnsOption[] { new EDnsOption(EDnsOptionCode.EXTENDED_DNS_ERROR, new EDnsExtendedDnsErrorOptionData(EDnsExtendedDnsErrorCode.StaleAnswer, null)) };
break;
}
options = [new EDnsOption(EDnsOptionCode.EXTENDED_DNS_ERROR, new EDnsExtendedDnsErrorOptionData(EDnsExtendedDnsErrorCode.StaleAnswer, null))];
break;
}
}
@@ -1026,23 +1024,23 @@ namespace DnsServerCore.Dns.ZoneManagers
while (true)
{
IReadOnlyList<DnsResourceRecord> closestAuthority = delegation.QueryRecords(DnsResourceRecordType.NS, serveStaleAndResetExpiry, true, eDnsClientSubnet, advancedForwardingClientSubnet);
IReadOnlyList<DnsResourceRecord> closestAuthority = delegation.QueryRecords(DnsResourceRecordType.NS, serveStale, true, eDnsClientSubnet, advancedForwardingClientSubnet);
if ((closestAuthority.Count > 0) && (closestAuthority[0].Type == DnsResourceRecordType.NS) && (closestAuthority[0].Name.Length > 0)) //dont trust root name servers from cache!
{
if (dnssecOk)
{
if (closestAuthority[0].DnssecStatus != DnssecStatus.Disabled) //dont return records with disabled status
{
closestAuthority = AddDSRecordsTo(delegation, serveStaleAndResetExpiry, closestAuthority, eDnsClientSubnet, advancedForwardingClientSubnet);
closestAuthority = AddDSRecordsTo(delegation, serveStale, closestAuthority, eDnsClientSubnet, advancedForwardingClientSubnet);
IReadOnlyList<DnsResourceRecord> additional = GetAdditionalRecords(closestAuthority, serveStaleAndResetExpiry, true, eDnsClientSubnet, advancedForwardingClientSubnet);
IReadOnlyList<DnsResourceRecord> additional = GetAdditionalRecords(closestAuthority, serveStale, true, eDnsClientSubnet, advancedForwardingClientSubnet);
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);
}
}
else
{
IReadOnlyList<DnsResourceRecord> additional = GetAdditionalRecords(closestAuthority, serveStaleAndResetExpiry, false, eDnsClientSubnet, advancedForwardingClientSubnet);
IReadOnlyList<DnsResourceRecord> additional = GetAdditionalRecords(closestAuthority, serveStale, false, eDnsClientSubnet, advancedForwardingClientSubnet);
return new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, request.CheckingDisabled, DnsResponseCode.NoError, request.Question, null, closestAuthority, additional);
}
@@ -1145,6 +1143,18 @@ namespace DnsServerCore.Dns.ZoneManagers
#region properties
public uint ServeStaleResetTtl
{
get { return _serveStaleResetTtl; }
set
{
if ((value < SERVE_STALE_MIN_RESET_TTL) || (value > SERVE_STALE_MAX_RESET_TTL))
throw new ArgumentOutOfRangeException(nameof(ServeStaleResetTtl), "Serve stale reset TTL must be between " + SERVE_STALE_MIN_RESET_TTL + " and " + SERVE_STALE_MAX_RESET_TTL + " seconds. Recommended value is 30 seconds.");
_serveStaleResetTtl = value;
}
}
public long MaximumEntries
{
get { return _maximumEntries; }