private async Task <IDictionary <string, string> > ResolvePtrTopClientsAsync(List <KeyValuePair <string, int> > topClients)
{
IDictionary <string, string> dhcpClientIpMap = _dnsWebService.DhcpServer.GetAddressHostNameMap();
async Task <KeyValuePair <string, string> > ResolvePtrAsync(string ip)
{
if (dhcpClientIpMap.TryGetValue(ip, out string dhcpDomain))
{
return(new KeyValuePair <string, string>(ip, dhcpDomain));
}
IPAddress address = IPAddress.Parse(ip);
if (IPAddress.IsLoopback(address))
{
return(new KeyValuePair <string, string>(ip, "localhost"));
}
DnsDatagram ptrResponse = await _dnsWebService.DnsServer.DirectQueryAsync(new DnsQuestionRecord(address, DnsClass.IN), 500);
if (ptrResponse.Answer.Count > 0)
{
IReadOnlyList <string> ptrDomains = DnsClient.ParseResponsePTR(ptrResponse);
if (ptrDomains.Count > 0)
{
return(new KeyValuePair <string, string>(ip, ptrDomains[0]));
}
}
return(new KeyValuePair <string, string>(ip, null));
}
List <Task <KeyValuePair <string, string> > > resolverTasks = new List <Task <KeyValuePair <string, string> > >();
foreach (KeyValuePair <string, int> item in topClients)
{
resolverTasks.Add(ResolvePtrAsync(item.Key));
}
Dictionary <string, string> result = new Dictionary <string, string>();
foreach (Task <KeyValuePair <string, string> > resolverTask in resolverTasks)
{
try
{
KeyValuePair <string, string> ptrResult = await resolverTask;
result[ptrResult.Key] = ptrResult.Value;
}
catch
{ }
}
return(result);
}