public static DNSResponse Lookup(string hostname, QType queryType, int timeout, List <IPEndPoint> dnsServers, bool useCache, bool async)
{
if (hostname == null || hostname.Trim().Length == 0)
{
return(null);
}
DNSResponse ipAddressResult = MatchIPAddress(hostname);
if (ipAddressResult != null)
{
return(ipAddressResult);
}
else if (useCache)
{
DNSResponse cacheResult = m_resolver.QueryCache(hostname.Trim().ToLower(), queryType);
if (cacheResult != null)
{
return(cacheResult);
}
}
if (async)
{
//logger.LogDebug("DNS lookup cache miss for async lookup to " + queryType.ToString() + " " + hostname + ".");
QueueLookup(new LookupRequest(hostname.Trim().ToLower(), queryType, timeout, dnsServers, null));
return(null);
}
else
{
ManualResetEvent completeEvent = new ManualResetEvent(false);
QueueLookup(new LookupRequest(hostname.Trim().ToLower(), queryType, timeout, dnsServers, completeEvent));
if (completeEvent.WaitOne(timeout * 1000 * 2, false))
{
//logger.LogDebug("Complete event fired for DNS lookup on " + queryType.ToString() + " " + hostname + ".");
// Completed event was fired, the DNS entry will now be in cache.
DNSResponse result = m_resolver.QueryCache(hostname, queryType);
if (result != null)
{
return(result);
}
else
{
//logger.LogDebug("DNS lookup cache miss for " + queryType.ToString() + " " + hostname + ".");
// Timeout.
DNSResponse timeoutResponse = new DNSResponse();
timeoutResponse.Timedout = true;
return(timeoutResponse);
}
}
else
{
// If this block gets called it's because the DNS resolver class did not return within twice the timeout period it
// was asked to do so in. If this happens a lot further investigation into the DNS resolver class is warranted.
logger.LogError("DNSManager timed out waiting for the DNS resolver to complete the lookup for " + queryType.ToString() + " " + hostname + ".");
// Timeout.
DNSResponse timeoutResponse = new DNSResponse();
timeoutResponse.Timedout = true;
return(timeoutResponse);
}
}
}
public override string ToString()
{
return(QType.ToString());
}