private async Task <bool> EnsureDnsRecordValue(string dnsRecord, string value, int attempt)
{
try
{
var dnsClients = await _lookupClientProvider.GetClients(dnsRecord, attempt);
foreach (var client in dnsClients)
{
_logger.LogDebug($"Preliminary validation will now check name server {client.IpAddress}");
var answers = await client.GetTextRecordValues(dnsRecord, attempt);
if (!answers.Any())
{
_logger.LogWarning($"Preliminary validation at {client.IpAddress} failed: no TXT records found");
return(false);
}
if (!answers.Contains(value))
{
_logger.LogWarning($"Preliminary validation at {client.IpAddress} failed: {value} not found in {string.Join(", ", answers)}");
return(false);
}
_logger.LogDebug($"Preliminary validation at {client.IpAddress} looks good!");
}
}
catch (Exception ex)
{
_logger.LogError(ex, "Preliminary validation failed");
return(false);
}
_logger.LogInformation("Preliminary validation succeeded");
return(true);
}
private async Task <IDnsQueryResponse> RecursivelyFollowCnames(IDnsQueryResponse result, int attempt)
{
if (result.Answers.CnameRecords().Any())
{
var cname = result.Answers.CnameRecords().First();
var recursiveClients = await _provider.GetClients(cname.CanonicalName, attempt);
var index = attempt % recursiveClients.Count;
var recursiveClient = recursiveClients.ElementAt(index);
var txtResponse = await recursiveClient.LookupClient.QueryAsync(cname.CanonicalName, QueryType.TXT);
return(await recursiveClient.RecursivelyFollowCnames(txtResponse, attempt));
}
return(result);
}