DnsQueryBody ParseDnsQueryBody(byte[] buffer, int beginIndex, ref int parseCount)
{
DnsQueryBody queryBody = new DnsQueryBody();
// get the length of the query name
int nameLength = 0;
int sectionLen, index = beginIndex;
while ((sectionLen = buffer[index]) != 0)
{
nameLength += sectionLen + 1;
index += sectionLen + 1;
}
nameLength += 1; // add the count of the last '0'
index++;
byte[] nameBuffer = new byte[nameLength];
Array.Copy(buffer, beginIndex, nameBuffer, 0, nameLength);
queryBody.queryName = nameBuffer;
queryBody.queryType = IPAddress.NetworkToHostOrder(BitConverter.ToInt16(buffer, index));
index += sizeof(Int16);
queryBody.queryClass = IPAddress.NetworkToHostOrder(BitConverter.ToInt16(buffer, index));
index += sizeof(Int16);
parseCount = index - beginIndex;
return(queryBody);
}
public void ExecuteTest()
{
Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
byte[] buffer = PrepareDnsQuery();
socket.SendTo(buffer, dnsServerEndPoint);
// Receive the response from the server
byte[] dnsData = new byte[1000];
EndPoint endPoint = (EndPoint)dnsServerEndPoint;
socket.ReceiveFrom(dnsData, ref endPoint);
int index = 0, count = 0;
DnsDiagramHead diagramHead = ParseResponseDiagramHead(dnsData, index, ref count);
index += count;
#region ErrorHandling
if (diagramHead.resRecNum == 0)
{
Console.WriteLine("Could not resolve the host name.");
return;
}
// rcode nonzero means error is found
if ((diagramHead.flag & 0x08) != 0)
{
Console.WriteLine("Dns Error! rcode =%d", (diagramHead.flag & 0x08));
return;
}
#endregion
// Make sure queryNum=1
Debug.Assert(diagramHead.queryNum == 1);
DnsQueryBody queryBody = ParseDnsQueryBody(dnsData, index, ref count);
index += count;
Console.WriteLine("Dns Query Name: " + queryBody.GetQueryNameString());
int resRecordCount = diagramHead.resRecNum;
DnsResourceRecord[] resourceRecords = new DnsResourceRecord[resRecordCount];
for (int i = 0; i < resRecordCount; i++)
{
resourceRecords[i] = ParseDnsResourceRecord(dnsData, index, ref count);
index += count;
}
foreach (DnsResourceRecord record in resourceRecords)
{
Console.WriteLine("Result is " + record.GetResourceContentString());
}
Console.WriteLine("\nPress any key to exit.");
Console.ReadKey();
}
