/// <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);
}
