/// <summary> Constructs the response object based upon the data received from the DNS server. </summary>
/// <param name="responseData">The data (byte[]) from the DNS server.</param>
/// <returns>Response message object.</returns>
public DnsResponseMessage ProcessResponse(ArraySegment <byte> responseData)
{
IDnsRecordFactory factory = new DnsRecordFactory(reader);
/*
* From index 0 till 11 bytes in the responseData array, we have the header items.
*/
ushort id = reader.ReadUInt16NetworkOrder(responseData);
ushort flags = reader.ReadUInt16NetworkOrder(responseData);
ushort questionCount = reader.ReadUInt16NetworkOrder(responseData);
ushort answerCount = reader.ReadUInt16NetworkOrder(responseData);
ushort nameServerCount = reader.ReadUInt16NetworkOrder(responseData);
ushort additionalCount = reader.ReadUInt16NetworkOrder(responseData);
/*
* We have got above data, now build the response header.
*/
DnsResponseHeader header = new DnsResponseHeader(id, flags, questionCount, answerCount, additionalCount, nameServerCount);
DnsResponseMessage response = new DnsResponseMessage(header, responseData.Count);
/*
* Next item in the response data is question that we sent to the DNS server which the server has copied onto the response message.
*/
for (int questionIndex = 0; questionIndex < questionCount; questionIndex++)
{
IDnsString questionString = reader.ReadQuestionQueryString(responseData);
DnsQuestion question = new DnsQuestion(questionString, (QueryType)reader.ReadUInt16NetworkOrder(responseData), (QueryClass)reader.ReadUInt16NetworkOrder(responseData));
response.AddQuestion(question);
}
for (int answerIndex = 0; answerIndex < answerCount; answerIndex++)
{
BaseResourceRecordInfo info = factory.ReadRecordInfo(responseData);
DnsResourceRecord record = factory.GetRecord(info, responseData);
response.AddAnswer(record);
}
for (int serverIndex = 0; serverIndex < nameServerCount; serverIndex++)
{
BaseResourceRecordInfo info = factory.ReadRecordInfo(responseData);
DnsResourceRecord record = factory.GetRecord(info, responseData);
response.AddAuthority(record);
}
for (int additionalIndex = 0; additionalIndex < additionalCount; additionalIndex++)
{
BaseResourceRecordInfo info = factory.ReadRecordInfo(responseData);
DnsResourceRecord record = factory.GetRecord(info, responseData);
response.AddAdditional(record);
}
return(response);
}
/*
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| |
| / /
| / NAME /
| |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| TYPE |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| CLASS |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| TTL |
| |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| RDLENGTH |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--|
| / RDATA /
| / /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
*/
public BaseResourceRecordInfo ReadRecordInfo(ArraySegment <byte> data)
{
IDnsString domainName = _reader.ReadQuestionQueryString(data); // domain name
ResourceRecordType recordType = (ResourceRecordType)_reader.ReadUInt16NetworkOrder(data); // record type
QueryClass queryClass = (QueryClass)_reader.ReadUInt16NetworkOrder(data); // query class
int timeToLive = (int)_reader.ReadUInt32NetworkOrder(data); // ttl - 32bit!!
int rawDataLength = _reader.ReadUInt16NetworkOrder(data); // RDLength
return(new BaseResourceRecordInfo(
recordType, // record type
queryClass, // query class
timeToLive, // ttl - 32bit!!
rawDataLength, // RDLength
domainName // domain name
));
}
