public static IPAddress[] Resolve(string host)
{
if(host == null){
throw new ArgumentNullException("host");
}
// If hostName_IP is IP
try{
return new IPAddress[]{IPAddress.Parse(host)};
}
catch{
}
// This is probably NetBios name
if(host.IndexOf(".") == -1){
return System.Net.Dns.GetHostEntry(host).AddressList;
}
else{
// hostName_IP must be host name, try to resolve it's IP
using(Dns_Client dns = new Dns_Client()){
DnsServerResponse resp = dns.Query(host,DNS_QType.A);
if(resp.ResponseCode == DNS_RCode.NO_ERROR){
DNS_rr_A[] records = resp.GetARecords();
IPAddress[] retVal = new IPAddress[records.Length];
for(int i=0;i<records.Length;i++){
retVal[i] = records[i].IP;
}
return retVal;
}
else{
throw new Exception(resp.ResponseCode.ToString());
}
}
}
}
public static string[] GetDomainHosts(string domain)
{
if(domain == null){
throw new ArgumentNullException("domain");
}
if(string.IsNullOrEmpty(domain)){
throw new ArgumentException("Invalid argument 'domain' value, you need to specify domain value.");
}
// We have email address, parse domain.
if(domain.IndexOf("@") > -1){
domain = domain.Substring(domain.IndexOf('@') + 1);
}
List<string> retVal = new List<string>();
// Get MX records.
using(Dns_Client dns = new Dns_Client()){
DnsServerResponse response = dns.Query(domain,DNS_QType.MX);
if(response.ResponseCode == DNS_RCode.NO_ERROR){
foreach(DNS_rr_MX mx in response.GetMXRecords()){
// Block invalid MX records.
if(!string.IsNullOrEmpty(mx.Host)){
retVal.Add(mx.Host);
}
}
}
else{
throw new DNS_ClientException(response.ResponseCode);
}
}
/* RFC 2821 5.
If no MX records are found, but an A RR is found, the A RR is treated as if it
was associated with an implicit MX RR, with a preference of 0, pointing to that host.
*/
if(retVal.Count == 0){
retVal.Add(domain);
}
return retVal.ToArray();
}
/// <summary>
/// Gets host name. If fails returns ip address.
/// </summary>
/// <param name="ip">IP address which to reverse lookup.</param>
/// <returns>Returns host name of specified IP address.</returns>
/// <exception cref="ArgumentNullException">Is raised when <b>ip</b> is null.</exception>
public static string GetHostName(IPAddress ip)
{
if(ip == null){
throw new ArgumentNullException("ip");
}
string retVal = ip.ToString();
try{
Dns_Client dns = new Dns_Client();
DnsServerResponse response = dns.Query(ip.ToString(),DNS_QType.PTR);
if(response.ResponseCode == DNS_RCode.NO_ERROR){
DNS_rr_PTR[] ptrs = response.GetPTRRecords();
if(ptrs.Length > 0){
retVal = ptrs[0].DomainName;
}
}
}
catch{
}
return retVal;
}
