/// <summary>
/// Get server IP for each MX entry. The last processed MX entry will add to _dataStorage fully processed
/// DomainMx instance
/// </summary>
/// <param name="entry"></param>
/// <returns></returns>
private async Task ProcessExchangeAsync(DomainMx.MxEntry entry)
{
if (_lookup == null)
{
return;
}
// find IP of each exchange server
try
{
var result = await _lookup.QueryAsync(entry.Exchange, QueryType.A, QueryClass.IN, _cancellation.Token);
entry.Error = result.HasError ? result.ErrorMessage : null;
if (entry.Error != null)
{
return;
}
var resp = result.Answers.ARecords().First();
entry.ExchangeIp = resp.Address.ToString();
}
finally
{
if (Interlocked.Increment(ref entry.Owner.mxProcessed) == entry.Owner.mxCount)
{
_dataStorage?.Add(entry.Owner);
}
}
}
/// <summary>
/// Process domain MX query, start new tasks for each of received MX entry
/// </summary>
/// <param name="domainMx"></param>
/// <returns></returns>
private async Task ProcessDomainAsync(DomainMx domainMx)
{
if (_lookup == null)
{
return;
}
int mxCount = 0;
var wasException = false;
try
{
var result = await _lookup.QueryAsync(domainMx.Domain, QueryType.MX, QueryClass.IN, _cancellation.Token);
domainMx.Error = result.HasError ? result.ErrorMessage : null;
// result.Answers.Count may be different than real MX records count in the case of redirection
var mxs = result.Answers.MxRecords();
mxCount = mxs.Count();
if (mxCount != result.Answers.Count)
{
domainMx.Error =
$@"Bad number ({mxCount}\{result.Answers.Count}) of received MX records. Probably redirects occurred.";
}
domainMx.mxCount = mxCount;
domainMx.MxArray = new DomainMx.MxEntry[mxCount];
if (Settings.Sort)
{
mxs = mxs.OrderBy(mx => mx.Preference);
}
var i = 0;
foreach (var mx in mxs)
{
var entry = new DomainMx.MxEntry(domainMx, mx.Exchange, mx.Preference);
ProcessExchange(entry);
domainMx.MxArray[i++] = entry;
}
}
catch (Exception e)
{
domainMx.Error = e.Message;
wasException = true;
}
finally
{
// log info about Domain even without MX (for reporting purposes)
if (mxCount == 0 || wasException)
{
_dataStorage?.Add(domainMx);
}
}
}
private void ProcessExchange(DomainMx.MxEntry entry) => _exchangeTasks.Add(ProcessExchangeAsync(entry));
