public static int Parse(out DnsQuestion question, byte[] array, int offset)
{
question = new DnsQuestion ();
question.DataPointer = offset;
int startingOffset = offset;
// Parse the domain name
byte partLength = 0;
var hostnameBuilder = new StringBuilder ();
while ((partLength = array[offset++]) > 0)
{
var domainPart = Encoding.UTF8.GetString (array, offset, partLength);
// Add separating dots
if (hostnameBuilder.Length > 0) {
hostnameBuilder.Append ('.');
}
hostnameBuilder.Append (domainPart);
offset += partLength;
// TODO: handle bytes larger than 255 chracters (LIMIT!)
}
// Parse the zone request type
// 2 bytes
var zoneType = (DnsZoneType)DnsEncoder.ParseUint16(array, offset);
offset += 2;
// Skip 2 bytes of QCLASS, we don't need them
var questionClass = (DnsRecordClass)DnsEncoder.ParseUint16(array, offset);
offset += 2;
// Wire up the data
question.Hostname = hostnameBuilder.ToString ();
question.ZoneType = zoneType;
question.Class = questionClass;
return offset - startingOffset;
}
/// <summary>
/// Parse the DnsQuery from the given UdpReceiveResult
/// </summary>
/// <param name="data"></param>
/// <returns></returns>
public static DnsQuery Parse(byte[] buffer, IPAddress remoteEndpoint)
{
// Create the query
var query = new DnsQuery();
query.Status = DnsQueryStatus.OK;
query.ClientIPAddress = remoteEndpoint;
// Parse the dns request header
query.Header = DnsMessageHeader.Parse(buffer, 0);
// DNS QUESTIONS:
int offset = 12;
for (int i = 0; i < query.Header.QuestionCount; i++)
{
try
{
// Save the question
DnsQuestion question;
offset += DnsQuestion.Parse(out question, buffer, offset);
if (question != null)
{
query.Questions.Add(question);
}
}
catch (Exception e) {
Console.WriteLine(e.Message);
Console.WriteLine(e.StackTrace);
query.Status = DnsQueryStatus.ParsingError;
break;
}
}
// Save the original question data to include it in the answer
query.OriginalQuestionData = new byte[offset];
Buffer.BlockCopy(buffer, 0, query.OriginalQuestionData, 0, offset);
// Parse the additional EDNS question
// For now, we only support a single additional question
if (query.Header.AdditionalQuestionCount > 0)
{
//Console.WriteLine("Reading OPT");
try
{
int bytesProcessed = 0;
query.EdnsQuestion = EdnsQuestion.Parse(buffer, offset, ref bytesProcessed);
offset += bytesProcessed;
// If the question was validely parsed, try using the subnet to assign the IP based on the user's location instead of the
// dns proxy server
if (query.EdnsQuestion != null)
{
var clientSubnetOption = (EdnsClientSubnetOption)query.EdnsQuestion.GetOption(EdnsOptionCode.ClientSubnet);
if (clientSubnetOption != null)
{
query.ClientIPAddress = clientSubnetOption.IPAddress;
}
}
}
catch (Exception e) {
Console.WriteLine(e.Message);
Console.WriteLine(e.StackTrace);
// If this fails, we still try to proceed normally
// TODO: log
}
}
return(query);
}
/// <summary>
/// Create a DnsAnswer linked to the given question
/// </summary>
/// <param name="dnsQuestion">DnsQuestion.</param>
public DnsAnswer (DnsQuestion dnsQuestion)
{
this.Question = dnsQuestion;
this.Hostname = null;
}
/// <summary>
/// Create a DnsAnswer linked to the given question
/// </summary>
/// <param name="dnsQuestion">DnsQuestion.</param>
public DnsAnswer(DnsQuestion dnsQuestion)
{
this.Question = dnsQuestion;
this.Hostname = null;
}
