private async Task <DnsMessage> ResolveMessageAsync(DomainName name, RecordType recordType, RecordClass recordClass, State state, CancellationToken token)
{
for (; state.QueryCount <= MaximumReferalCount; state.QueryCount++)
{
DnsMessage msg = await new DnsClient(GetBestNameservers(recordType == RecordType.Ds ? name.GetParentName() : name), QueryTimeout)
{
IsResponseValidationEnabled = IsResponseValidationEnabled,
Is0x20ValidationEnabled = Is0x20ValidationEnabled
}.ResolveAsync(name, recordType, recordClass, new DnsQueryOptions()
{
IsRecursionDesired = false,
IsEDnsEnabled = true
}, token);
if ((msg != null) && ((msg.ReturnCode == ReturnCode.NoError) || (msg.ReturnCode == ReturnCode.NxDomain)))
{
if (msg.IsAuthoritiveAnswer)
{
return(msg);
}
List <NsRecord> referalRecords = msg.AuthorityRecords
.Where(x =>
(x.RecordType == RecordType.Ns) &&
(name.Equals(x.Name) || name.IsSubDomainOf(x.Name)))
.OfType <NsRecord>()
.ToList();
if (referalRecords.Count > 0)
{
if (referalRecords.GroupBy(x => x.Name).Count() == 1)
{
var newServers = referalRecords.Join(msg.AdditionalRecords.OfType <AddressRecordBase>(), x => x.NameServer, x => x.Name, (x, y) => new { y.Address, TimeToLive = Math.Min(x.TimeToLive, y.TimeToLive) }).ToList();
if (newServers.Count > 0)
{
DomainName zone = referalRecords.First().Name;
foreach (var newServer in newServers)
{
_nameserverCache.Add(zone, newServer.Address, newServer.TimeToLive);
}
continue;
}
else
{
NsRecord firstReferal = referalRecords.First();
var newLookedUpServers = await ResolveHostWithTtlAsync(firstReferal.NameServer, state, token);
foreach (var newServer in newLookedUpServers)
{
_nameserverCache.Add(firstReferal.Name, newServer.Item1, Math.Min(firstReferal.TimeToLive, newServer.Item2));
}
if (newLookedUpServers.Count > 0)
{
continue;
}
}
}
}
// Response of best known server is not authoritive and has no referrals --> No chance to get a result
throw new Exception("Could not resolve " + name);
}
}
// query limit reached without authoritive answer
throw new Exception("Could not resolve " + name);
}
} // End Class DbDnsRecord
static async Task <bool> ResolveMessage(DnsMessage query, QueryReceivedEventArgs e, DnsMessage response)
{
DbDnsRecord rec = null;
using (System.Data.Common.DbCommand cmd = s_sql.CreateCommand(@"
-- DECLARE @in_recordType int
-- DECLARE @in_recordName varchar(4000)
-- SET @in_recordType = 1 -- A
-- SET @in_recordName = 'vortex.data.microsoft.com'
SELECT
REC_Id
--,T_Records.REC_DOM_Id
,T_Records.REC_RT_Id
,T_Records.REC_Name
,T_Records.REC_Content
,T_Records.REC_ResponsibleName
,COALESCE(T_Records.REC_TTL, 100) AS REC_TTL
,T_Records.REC_Prio
,T_Records.REC_Weight
,T_Records.REC_Port
,T_Records.REC_SerialNumber
,T_Records.REC_RefreshInterval
,T_Records.REC_RetryInterval
,T_Records.REC_ExpireInterval
,T_Records.REC_NegativeCachingTTL
,T_Records.REC_AfsSubType
,T_Records.REC_ChangeDate
FROM T_Records
WHERE REC_RT_Id = @in_recordType
AND T_Records.REC_Name = @in_recordName
;
"))
{
try
{
string name = query.Questions[0].Name.ToString();
s_sql.AddParameter(cmd, "in_recordType", (int)query.Questions[0].RecordType);
s_sql.AddParameter(cmd, "in_recordName", name);
// TODO: Can return multiple records...
rec = s_sql.GetClass <DbDnsRecord>(cmd);
}
catch (System.Exception ex)
{
System.Console.WriteLine(ex.Message);
System.Console.WriteLine(ex.StackTrace);
}
} // End Using cmd
if (rec != null)
{
int ttl = 3600;
DnsRecordBase record = null;
// https://blog.dnsimple.com/2015/04/common-dns-records/
// https://en.wikipedia.org/wiki/List_of_DNS_record_types
switch ((RecordType)rec.REC_RT_Id)
{
case RecordType.Soa:
// SoaRecord(DomainName name, int timeToLive, DomainName masterName
// , DomainName responsibleName, uint serialNumber, int refreshInterval
// , int retryInterval, int expireInterval, int negativeCachingTTL)
record = new ARSoft.Tools.Net.Dns.SoaRecord(
DomainName.Parse(rec.REC_Name)
, rec.REC_TTL.Value
, DomainName.Parse(rec.REC_Content)
, DomainName.Parse(rec.REC_ResponsibleName)
, rec.REC_SerialNumber.Value
, rec.REC_RefreshInterval.Value
, rec.REC_RetryInterval.Value
, rec.REC_ExpireInterval.Value
, rec.REC_NegativeCachingTTL.Value
);
break;
case RecordType.Ns:
record = new ARSoft.Tools.Net.Dns.NsRecord(DomainName.Parse(rec.REC_Name), ttl, DomainName.Parse(rec.REC_Content));
break;
case RecordType.Srv:
// SrvRecord(DomainName name, int timeToLive, ushort priority, ushort weight, ushort port, DomainName target)
record = new ARSoft.Tools.Net.Dns.SrvRecord(DomainName.Parse(rec.REC_Name), rec.REC_TTL.Value, (ushort)rec.REC_Prio.Value, (ushort)rec.REC_Weight.Value, (ushort)rec.REC_Port.Value, DomainName.Parse(rec.REC_Content));
break;
// https://www.openafs.org/
// https://en.wikipedia.org/wiki/OpenAFS
// http://www.rjsystems.nl/en/2100-dns-discovery-openafs.php
// OpenAFS is an open source implementation of the Andrew distributed file system(AFS).
case RecordType.Afsdb:
// http://www.rjsystems.nl/en/2100-dns-discovery-openafs.php
record = new ARSoft.Tools.Net.Dns.AfsdbRecord(DomainName.Parse(rec.REC_Name), rec.REC_TTL.Value, (AfsdbRecord.AfsSubType)(uint) rec.REC_AfsSubType.Value, DomainName.Parse(rec.REC_Content));
break;
// A DNS-based Authentication of Named Entities (DANE) method
// for publishing and locating OpenPGP public keys in DNS
// for a specific email address using an OPENPGPKEY DNS resource record.
case RecordType.OpenPGPKey:
byte[] publicKey = null;
// hexdump(sha256(truncate(utf8(ocalpart), 28)
// https://www.huque.com/bin/openpgpkey
// The OPENPGPKEY DNS record is specied in RFC 7929.
// The localpart of the uid is encoded as a DNS label
// containing the hexdump of the SHA-256 hash
// of the utf-8 encoded localpart, truncated to 28 octets.
// Normally the "Standard" output format should be used.
// The "Generic Encoding" output format is provided to help work
// with older DNS software that does not yet understand the OPENPGPKEY record type.
record = new ARSoft.Tools.Net.Dns.OpenPGPKeyRecord(DomainName.Parse(rec.REC_Name), ttl, publicKey);
break;
// Canonical name records, or CNAME records, are often called alias records because they map an alias to the canonical name. When a name server finds a CNAME record, it replaces the name with the canonical name and looks up the new name.
case RecordType.CName:
record = new ARSoft.Tools.Net.Dns.CNameRecord(DomainName.Parse(rec.REC_Name), rec.REC_TTL.Value, DomainName.Parse(rec.REC_Content));
break;
case RecordType.Ptr:
record = new ARSoft.Tools.Net.Dns.PtrRecord(DomainName.Parse(rec.REC_Name), rec.REC_TTL.Value, DomainName.Parse(rec.REC_Content));
break;
case RecordType.A:
record = new ARSoft.Tools.Net.Dns.ARecord(DomainName.Parse(rec.REC_Name), rec.REC_TTL.Value, System.Net.IPAddress.Parse(rec.REC_Content));
break;
case RecordType.Aaaa:
record = new ARSoft.Tools.Net.Dns.AaaaRecord(DomainName.Parse(rec.REC_Name), rec.REC_TTL.Value, System.Net.IPAddress.Parse(rec.REC_Content));
break;
case RecordType.Mx:
record = new ARSoft.Tools.Net.Dns.MxRecord(DomainName.Parse(rec.REC_Name), rec.REC_TTL.Value, 0, DomainName.Parse(rec.REC_Content));
break;
case RecordType.Txt:
record = new ARSoft.Tools.Net.Dns.TxtRecord(DomainName.Parse(rec.REC_Name), rec.REC_TTL.Value, rec.REC_Content);
break;
case RecordType.SshFp:
// https://unix.stackexchange.com/questions/121880/how-do-i-generate-sshfp-records
// SshFpRecord(DomainName name, int timeToLive, SshFpAlgorithm algorithm
// , SshFpFingerPrintType fingerPrintType, byte[] fingerPrint)
ARSoft.Tools.Net.Dns.SshFpRecord.SshFpAlgorithm sfa = ARSoft.Tools.Net.Dns.SshFpRecord
.SshFpAlgorithm.Rsa;
ARSoft.Tools.Net.Dns.SshFpRecord.SshFpFingerPrintType sfp = ARSoft.Tools.Net.Dns.SshFpRecord
.SshFpFingerPrintType.Sha256;
byte[] fp = null;
record = new ARSoft.Tools.Net.Dns.SshFpRecord(DomainName.Parse(rec.REC_Name), rec.REC_TTL.Value, sfa, sfp, fp);
break;
default:
break;
} // End Switch
if (record != null)
{
response.AnswerRecords.Add(record);
}
response.ReturnCode = ReturnCode.NoError;
e.Response = response;
return(await Task <bool> .FromResult(true));
} // End if (rec != null)
return(await Task <bool> .FromResult(false));
} // End Function ResolveMessage
