public static List <NameServerAddress> GetNameServersFromResponse(DnsDatagram response, bool preferIPv6)
{
IReadOnlyList <DnsResourceRecord> authorityRecords;
if ((response.Question.Count > 0) && (response.Question[0].Type == DnsResourceRecordType.NS) && (response.Answer.Count > 0) && (response.Answer[0].Type == DnsResourceRecordType.NS))
{
authorityRecords = response.Answer;
}
else
{
authorityRecords = response.Authority;
}
List <NameServerAddress> nameServers = new List <NameServerAddress>(authorityRecords.Count);
foreach (DnsResourceRecord authorityRecord in authorityRecords)
{
if (authorityRecord.Type == DnsResourceRecordType.NS)
{
DnsNSRecord nsRecord = (DnsNSRecord)authorityRecord.RDATA;
IPEndPoint endPoint = null;
//find ip address of authoritative name server from additional records
foreach (DnsResourceRecord rr in response.Additional)
{
if (nsRecord.NameServer.Equals(rr.Name, StringComparison.OrdinalIgnoreCase))
{
switch (rr.Type)
{
case DnsResourceRecordType.A:
endPoint = new IPEndPoint(((DnsARecord)rr.RDATA).Address, 53);
nameServers.Add(new NameServerAddress(nsRecord.NameServer, endPoint));
break;
case DnsResourceRecordType.AAAA:
endPoint = new IPEndPoint(((DnsAAAARecord)rr.RDATA).Address, 53);
if (preferIPv6)
{
nameServers.Add(new NameServerAddress(nsRecord.NameServer, endPoint));
}
break;
}
}
}
if (endPoint == null)
{
nameServers.Add(new NameServerAddress(new DomainEndPoint(nsRecord.NameServer, 53)));
}
}
}
return(nameServers);
}
public static NameServerAddress[] GetNameServersFromResponse(DnsDatagram response, bool preferIPv6)
{
List <NameServerAddress> nameServers = new List <NameServerAddress>(response.Authority.Length);
foreach (DnsResourceRecord authorityRecord in response.Authority)
{
if (authorityRecord.Type == DnsResourceRecordType.NS)
{
DnsNSRecord nsRecord = (DnsNSRecord)authorityRecord.RDATA;
IPEndPoint endPoint = null;
//find ip address of authoritative name server from additional records
foreach (DnsResourceRecord rr in response.Additional)
{
if (nsRecord.NSDomainName.Equals(rr.Name, StringComparison.CurrentCultureIgnoreCase))
{
switch (rr.Type)
{
case DnsResourceRecordType.A:
endPoint = new IPEndPoint(((DnsARecord)rr.RDATA).Address, 53);
nameServers.Add(new NameServerAddress(nsRecord.NSDomainName, endPoint));
break;
case DnsResourceRecordType.AAAA:
endPoint = new IPEndPoint(((DnsAAAARecord)rr.RDATA).Address, 53);
if (preferIPv6)
{
nameServers.Add(new NameServerAddress(nsRecord.NSDomainName, endPoint));
}
break;
}
}
}
if (endPoint == null)
{
nameServers.Add(new NameServerAddress(new DomainEndPoint(nsRecord.NSDomainName, 53)));
}
}
}
NameServerAddress[] nsArray = nameServers.ToArray();
DnsClient.ShuffleArray(nsArray);
if (preferIPv6)
{
Array.Sort(nsArray);
}
return(nsArray);
}
public override bool Equals(object obj)
{
if (ReferenceEquals(null, obj))
{
return(false);
}
if (ReferenceEquals(this, obj))
{
return(true);
}
DnsNSRecord other = obj as DnsNSRecord;
if (other == null)
{
return(false);
}
return(this._nsDomainName.Equals(other._nsDomainName, StringComparison.OrdinalIgnoreCase));
}
private IReadOnlyList <DnsResourceRecord> GetAdditionalRecords(IReadOnlyList <DnsResourceRecord> refRecords)
{
List <DnsResourceRecord> additionalRecords = new List <DnsResourceRecord>();
foreach (DnsResourceRecord refRecord in refRecords)
{
switch (refRecord.Type)
{
case DnsResourceRecordType.NS:
DnsNSRecord nsRecord = refRecord.RDATA as DnsNSRecord;
if (nsRecord is not null)
{
ResolveAdditionalRecords(refRecord, nsRecord.NameServer, additionalRecords);
}
break;
case DnsResourceRecordType.MX:
DnsMXRecord mxRecord = refRecord.RDATA as DnsMXRecord;
if (mxRecord is not null)
{
ResolveAdditionalRecords(refRecord, mxRecord.Exchange, additionalRecords);
}
break;
case DnsResourceRecordType.SRV:
DnsSRVRecord srvRecord = refRecord.RDATA as DnsSRVRecord;
if (srvRecord is not null)
{
ResolveAdditionalRecords(refRecord, srvRecord.Target, additionalRecords);
}
break;
}
}
return(additionalRecords);
}
