public DnsQueryQuestion(IDnsNameParser parser, byte[] packetContent, int startingOffset, int questionLength)
: this()
{
Name = parser.GetNameAtOffset(startingOffset);
Bytes = null;
RecordType = (DnsRecordType)BitConverter.ToInt16(new byte[] { packetContent[startingOffset + questionLength - 3], packetContent[startingOffset + questionLength - 4] }, 0);
RecordClass = (DnsRecordClass)BitConverter.ToInt16(new byte[] { packetContent[startingOffset + questionLength - 1], packetContent[startingOffset + questionLength - 2] }, 0);
}
private IDnsQueryAnswer GetDnsQueryAnswer(IDnsNameParser parser, DnsName name, DnsRecordType recordType, DnsRecordClass recordClass, UInt32 ttl, short recordDataLength, int recordDataOffset, byte[] packetContent)
{
var answer = GetDnsQueryAnswer(parser, recordType, recordDataLength, null, packetContent, recordDataOffset);
answer.Name = name;
answer.RecordType = recordType;
answer.RecordClass = recordClass;
answer.Ttl = ttl;
answer.RecordDataLength = recordDataLength;
//answer.RecordData = recordData;
return answer;
}
/// <summary>
///
/// </summary>
/// <param name="packetContent"></param>
/// <param name="startingOffset">The starting offset of the name, the value of the length of the first name part</param>
public DnsName(IDnsNameParser parser, byte[] packetContent, int startingOffset)
: this()
{
var host = new StringBuilder();
var numberOfCharactersInCurrentNameSection = Convert.ToInt32(packetContent[startingOffset]);
var i = startingOffset + 1;
while (packetContent[i] != 0 && i < packetContent.Length - 1)
{
var twoBytes = packetContent.Skip(i).Take(2);
var twoBytesAsBits = new BitArray(twoBytes.Reverse().ToArray());
if (twoBytesAsBits[14] && twoBytesAsBits[15])
{
// We have a "pointer"
var name = parser.GetNameAtOffset(twoBytes.Last());
if (host.Length != 0)
{
host.Append(".");
}
host.Append(name);
break;
}
if (numberOfCharactersInCurrentNameSection > 0)
{
host.Append(Convert.ToChar(packetContent[i]));
numberOfCharactersInCurrentNameSection--;
}
else
{
if (packetContent[i] == 0)
{
break;
}
else
{
host.Append(".");
numberOfCharactersInCurrentNameSection = Convert.ToInt32(packetContent[i]);
}
}
i++;
}
Host = host.ToString();
Bytes = packetContent;
}
private IDnsQueryAnswer GetDnsQueryAnswer(IDnsNameParser parser, DnsRecordType recordType, short recordDataLength, byte[] recordData, byte[] packetContent, int recordDataOffset)
{
switch (recordType)
{
case DnsRecordType.A:
return new DnsQueryAnswerA(parser, recordDataLength, recordDataOffset, packetContent);
case DnsRecordType.CNAME:
return new DnsQueryAnswerCName(parser, recordDataLength, recordDataOffset, packetContent);
case DnsRecordType.MX:
return new DnsQueryAnswerMx(parser, recordDataLength, recordDataOffset, packetContent);
case DnsRecordType.NS:
return new DnsQueryAnswerNS(parser, recordDataLength, recordDataOffset, packetContent);
case DnsRecordType.AAAA:
case DnsRecordType.SRV:
default:
return new DnsQueryAnswerGeneric();
}
}
public IDnsQueryAnswer GetDnsQueryAnswer(IDnsNameParser parser, byte[] packetContent, ref int startOfAnswer)
{
IDnsQueryAnswer answer = null;
var twoBytes = packetContent.Skip(startOfAnswer).Take(2);
var twoBytesAsBits = new BitArray(twoBytes.Reverse().ToArray());
if (twoBytesAsBits[14] && twoBytesAsBits[15])
{
// We have a "pointer"
var name = parser.GetNameAtOffset(twoBytes.Last());
var recordType = (DnsRecordType)BitConverter.ToInt16(packetContent.Skip(startOfAnswer + 2).Take(2).Reverse().ToArray(), 0);
var recordClass = (DnsRecordClass)BitConverter.ToInt16(packetContent.Skip(startOfAnswer + 4).Take(2).Reverse().ToArray(), 0);
var ttl = BitConverter.ToUInt32(packetContent.Skip(startOfAnswer + 6).Take(4).Reverse().ToArray(), 0);
var rDataLength = BitConverter.ToInt16(packetContent.Skip(startOfAnswer + 10).Take(2).Reverse().ToArray(), 0);
var recordDataOffset = startOfAnswer + 12;
answer = GetDnsQueryAnswer(parser, name, recordType, recordClass, ttl, rDataLength, recordDataOffset, packetContent);
startOfAnswer = startOfAnswer + 12 + rDataLength;
}
return answer;
}
public DnsQueryAnswerMx(IDnsNameParser parser, short recordDataLength, int recordDataOffset, byte[] packetContent)
{
Preference = BitConverter.ToInt16(packetContent.Skip(recordDataOffset).Take(2).ToArray(), 0);
MxName = parser.GetNameAtOffset(recordDataOffset + 2);
}
private DnsQueryQuestion ExtractQuestion(IDnsNameParser parser, byte[] packetContent, ref int startOfQuestion)
{
DnsQueryQuestion? question = null;
for (int i = startOfQuestion; i < packetContent.Length; i++)
{
// We've found the null that terminates
if (packetContent[i] == 0)
{
var endOfQuestion = i + 5;
question = new DnsQueryQuestion(parser, packetContent, startOfQuestion, (i + 5) - startOfQuestion);
startOfQuestion = endOfQuestion + 1;
break;
}
}
return question.Value;
}
public DnsQueryAnswerCName(IDnsNameParser parser, short recordDataLength, int recordDataOffset, byte[] packetContent)
{
CName = parser.GetNameAtOffset(recordDataOffset);
}
public DnsQueryAnswerA(IDnsNameParser parser, short recordDataLength, int recordDataOffset, byte[] packetContent)
{
IPAddress = new IPAddress(packetContent.Skip(recordDataOffset).Take(recordDataLength).ToArray());
}
