/// <summary>
/// Look up a DNS SRV record, returning the best host and port number to connect to.
/// </summary>
/// <param name="prefix">The SRV prefix, ending with a dot. Example: "_xmpp-client._tcp."</param>
/// <param name="domain">The domain to check</param>
/// <param name="host">The host name to connect to</param>
/// <param name="port">The port number to connect to</param>
public static void LookupSRV(string prefix, string domain, ref string host, ref int port)
{
if (prefix == null)
{
throw new ArgumentNullException("prefix");
}
if (domain == null)
{
throw new ArgumentNullException("domain");
}
if (!prefix.EndsWith("."))
{
throw new ArgumentOutOfRangeException("Prefix must end in '.'", "prefix");
}
try
{
IList <SRVRecord> srvRecords = DnsServiceFactory.Create().GetSrvRecords(prefix + domain);
SRVRecord record = PickSRV(srvRecords.ToArray());
host = record.NameNext;
port = record.Port;
Debug.WriteLine(string.Format("SRV found: {0}:{1}", host, port));
}
catch
{
host = domain;
}
}
/// <summary>
/// Look up a DNS TXT record.
/// </summary>
/// <param name="prefix">The prefix, ending in '.'. Example: "_xmppconnect."</param>
/// <param name="domain">The domain to search</param>
/// <param name="attribute">The attribute name to look for. Example: "_xmpp-client-xbosh"</param>
/// <returns></returns>
public static string LookupTXT(string prefix, string domain, string attribute)
{
if (prefix == null)
{
throw new ArgumentNullException("prefix");
}
if (domain == null)
{
throw new ArgumentNullException("domain");
}
if (attribute == null)
{
throw new ArgumentNullException("attribute");
}
if (!prefix.EndsWith("."))
{
throw new ArgumentOutOfRangeException("Prefix must end in '.'", "prefix");
}
try
{
IList <TXTRecord> txtRecords = DnsServiceFactory.Create().GetTxtRecords(prefix + domain);
string attr = attribute + "=";
foreach (TXTRecord txt in txtRecords)
{
if (txt.StringArray.StartsWith(attr))
{
Debug.WriteLine(string.Format("TXT found: {0}", txt.StringArray));
return(txt.StringArray.Substring(attr.Length));
}
}
}
catch
{
}
return(null);
}
