private async Task QueryDns(string domain, string servicePrefix, List <DnsRecord> records)
{
var lookup = Invariant($"{servicePrefix}.{domain}");
bool skipLookup = false;
if (DomainServiceNegativeCache.TryGetValue(lookup, out DateTimeOffset expires))
{
if (DateTimeOffset.UtcNow > expires)
{
DomainServiceNegativeCache.TryRemove(lookup, out _);
}
else
{
skipLookup = true;
}
}
if (!skipLookup)
{
this.logger.LogDebug("Querying DNS {Lookup}", lookup);
var dnsResults = await DnsQuery.QuerySrv(lookup);
if (!dnsResults.Any())
{
DomainServiceNegativeCache[lookup] = DateTimeOffset.UtcNow.AddMinutes(5);
this.logger.LogDebug("DNS failed {Lookup} so negative caching", lookup);
}
records.AddRange(dnsResults);
}
}
public void TestFailedLookup()
{
DnsQuery.Debug = true;
var records = DnsQuery.QuerySrv(UnknownSrvRecord);
Assert.AreEqual(0, records.Count());
}
public async Task FailedLookup()
{
DnsQuery.Debug = true;
var records = await DnsQuery.QuerySrv(UnknownSrvRecord);
Assert.AreEqual(0, records.Count());
}
public void TestQuerySrvRecordHittingInternet()
{
DnsQuery.Debug = true;
var records = DnsQuery.QuerySrv(ExternalSrvRecord);
Assert.IsTrue(records.Count() > 0);
var srv = records.Single(r => r.Type == DnsRecordType.SRV);
Assert.AreEqual("sipdir.online.lync.com", srv.Target);
Assert.AreEqual(443, srv.Port);
}
public async Task QuerySrvRecordHittingInternet()
{
DnsQuery.Debug = true;
var records = await DnsQuery.QuerySrv(ExternalSrvRecord);
Assert.IsTrue(records.Any());
var srv = records.Single(r => r.Type == DnsRecordType.SRV);
Assert.AreEqual("sipdir.online.lync.com", srv.Target);
Assert.AreEqual(443, srv.Port);
}
public async Task QueryUsesCustomType()
{
var fake = new FakeDnsImplementation();
DnsQuery.RegisterImplementation(fake);
var result = await DnsQuery.QuerySrv("blah.blah.blah");
Assert.AreEqual(1, result.Count());
Assert.AreEqual("blah", result.First().Target);
Assert.IsTrue(fake.WasCalled);
DnsQuery.RegisterImplementation(new WindowsDnsQuery());
}
protected virtual IEnumerable <DnsRecord> Query(string lookup)
{
return(DnsQuery.QuerySrv(lookup));
}
public void TestBadDataLookup()
{
DnsQuery.QuerySrv(BadSrvRecord);
}
public async Task BadDataLookup()
{
await DnsQuery.QuerySrv(BadSrvRecord);
}
