public static DnsQuery ReadDnsQuery(BinaryReader reader)
{
String domainName = ReadDomainName(reader);
QueryType qtype = (QueryType)ReadUInt16BE(reader);
QueryClass qclass = (QueryClass)ReadUInt16BE(reader);
DnsQuery query = new DnsQuery(domainName, qtype, qclass);
return(query);
}
/* 4.1.2. Question section format
* 1 1 1 1 1 1
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| |
| / QNAME /
| / /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| QTYPE |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| QCLASS |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|
| QNAME
| a domain name represented as a sequence of labels, where
| each label consists of a length octet followed by that
| number of octets. The domain name terminates with the
| zero length octet for the null label of the root. Note
| that this field may be an odd number of octets; no
| padding is used.
*/
public static byte[] EncodeDnsQuery(DnsQuery query)
{
MemoryStream stream = new MemoryStream(256);
BinaryWriter writer = new BinaryWriter(stream);
//QNAME
string[] labels = query.DomainName.Split('.');
foreach (string label in labels)
{
writer.Write((byte)label.Length);
writer.Write(Encoding.ASCII.GetBytes(label));
}
writer.Write((byte)0);
//QTYPE
WriteUInt16BE(writer, (UInt16)query.QueryType);
//QCLASS
WriteUInt16BE(writer, (UInt16)query.QueryClass);
return(stream.ToArray());
}
public static DnsQuery ReadDnsQuery(BinaryReader reader)
{
String domainName = ReadDomainName(reader);
QueryType qtype = (QueryType)ReadUInt16BE(reader);
QueryClass qclass = (QueryClass)ReadUInt16BE(reader);
DnsQuery query = new DnsQuery(domainName, qtype, qclass);
return query;
}
/* 4.1.2. Question section format
1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| |
/ QNAME /
/ /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| QTYPE |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| QCLASS |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
QNAME
a domain name represented as a sequence of labels, where
each label consists of a length octet followed by that
number of octets. The domain name terminates with the
zero length octet for the null label of the root. Note
that this field may be an odd number of octets; no
padding is used.
*/
public static byte[] EncodeDnsQuery(DnsQuery query)
{
MemoryStream stream = new MemoryStream(256);
BinaryWriter writer = new BinaryWriter(stream);
//QNAME
string[] labels = query.DomainName.Split('.');
foreach (string label in labels)
{
writer.Write((byte)label.Length);
writer.Write(Encoding.ASCII.GetBytes(label));
}
writer.Write((byte)0);
//QTYPE
WriteUInt16BE(writer, (UInt16)query.QueryType);
//QCLASS
WriteUInt16BE(writer, (UInt16)query.QueryClass);
return stream.ToArray();
}
/// <summary>
/// Get IPHostEntry for given domainName.
/// </summary>
/// <param name="domainName">domainName</param>
/// <param name="queryType">QueryType.Address or QueryType.MailExchange</param>
/// <param name="dnsServer">dnsServer</param>
/// <returns></returns>
public static IPHostEntry GetIPHostEntry(string domainName, QueryType queryType, IPAddress dnsServer)
{
DnsMessage message = DnsMessage.StandardQuery();
DnsQuery query = new DnsQuery(domainName, queryType);
message.Querys.Add(query);
byte[] msgData = DnsMessageCoder.EncodeDnsMessage(message);
try
{
byte[] reply = QueryServer(msgData, dnsServer);
if (reply != null)
{
DnsMessage answer = DnsMessageCoder.DecodeDnsMessage(reply);
if (answer.ID == message.ID)
{
if (answer.Answers.Count > 0)
{
IPHostEntry host = new IPHostEntry();
host.HostName = domainName;
if (queryType == QueryType.Address)
{
host.AddressList = GetAddressList(domainName, answer);
}
else if (queryType == QueryType.MailExchange)
{
host.Aliases = GetMailExchangeAliases(domainName, answer);
host.AddressList = GetAddressList(answer, new List<string>(host.Aliases));
}
return host;
}
else if (answer.AuthorityRecords.Count > 0)
{
IPAddress[] serverAddresses = GetAuthorityServers(answer);
// depth first search
foreach (IPAddress serverIP in serverAddresses)
{
IPHostEntry host = GetIPHostEntry(domainName, queryType, serverIP);
if (host != null)
{
return host;
}
}
}
}
}
}
catch { }
return null;
}
