public DnsQuery(string name, DnsQType qtype, DnsQClass qclass)
{
if (String.IsNullOrEmpty(name))
{
throw new ArgumentNullException("name");
}
int length = DnsUtil.GetEncodedLength(name);
if (length == -1)
{
throw new ArgumentException("Invalid DNS name", "name");
}
length += 12 + 2 + 2; // Header + qtype + qclass
packet = new byte [length];
header = new DnsHeader(packet, 0);
position = 12;
WriteDnsName(name);
WriteUInt16((ushort)qtype);
WriteUInt16((ushort)qclass);
Header.QuestionCount = 1;
Header.IsQuery = true;
Header.RecursionDesired = true;
}
protected void WriteDnsName(string name)
{
if (!DnsUtil.IsValidDnsName(name))
{
throw new ArgumentException("Invalid DNS name");
}
if (!String.IsNullOrEmpty(name))
{
int len = name.Length;
int label_start = 0;
int label_len = 0;
for (int i = 0; i < len; i++)
{
char c = name [i];
if (c != '.')
{
label_len++;
}
else
{
if (i == 0)
{
break; // "."
}
WriteLabel(name, label_start, label_len);
label_start += label_len + 1; // Skip the dot
label_len = 0;
}
}
if (label_len > 0)
{
WriteLabel(name, label_start, label_len);
}
}
packet [position++] = 0;
}
protected internal static string ReadName(byte [] buffer, ref int offset)
{
return(DnsUtil.ReadName(buffer, ref offset));
}
protected internal string ReadName(ref int offset)
{
return(DnsUtil.ReadName(packet, ref offset));
}