public async Task Lookup_RetryOnDnsErrorAndThrowAsync()
{
var lookup = new LookupClient(
new NameServer(IPAddress.Parse("127.0.0.1")),
new NameServer(IPAddress.Parse("127.0.0.2")),
new NameServer(IPAddress.Parse("127.0.0.3")))
{
EnableAuditTrail = true,
ContinueOnDnsError = true,
ThrowDnsErrors = true
};
var calledIps = new List <IPAddress>();
var messageHandler = new TestMessageHandler((ip, req) =>
{
calledIps.Add(ip.Address);
if (ip.Address.Equals(IPAddress.Parse("127.0.0.3")))
{
// last one returns different result
return(new DnsResponseMessage(
new DnsResponseHeader(1, (int)DnsResponseCode.FormatError, 0, 0, 0, 0),
0));
}
return(new DnsResponseMessage(
new DnsResponseHeader(1, (int)DnsResponseCode.NotExistentDomain, 0, 0, 0, 0),
0));
});
var request = new DnsRequestMessage(
new DnsRequestHeader(0, DnsOpCode.Query),
new DnsQuestion("test.com", QueryType.A, QueryClass.IN));
// all three servers have been called and we get the last exception thrown
var result = await Assert.ThrowsAnyAsync <DnsResponseException>(() => lookup.ResolveQueryAsync(lookup.GetNextServers(), messageHandler, request, false));
// ensure the error is the one from the last call
Assert.Equal(DnsResponseCode.FormatError, result.Code);
// ensuer all 3 configured servers were called before throwing the exception
Assert.Equal(3, calledIps.Count);
}
public async Task Lookup_ShuffleNameServerOrderAsync()
{
var lookup = new LookupClient(
new NameServer(IPAddress.Parse("127.0.0.1")),
new NameServer(IPAddress.Parse("127.0.0.2")),
new NameServer(IPAddress.Parse("127.0.0.3")))
{
// default is true
UseRandomNameServer = true
};
var calledIps = new List <IPAddress>();
var messageHandler = new TestMessageHandler((ip, req) =>
{
calledIps.Add(ip.Address);
return(new DnsResponseMessage(
new DnsResponseHeader(1, (int)DnsResponseCode.NoError, 0, 0, 0, 0),
0));
});
// consecutive calls should cycle through the servers (not always using the first one)
// because this is only one thread, the order is always the same. But this can be very
// different with multiple tasks)
for (var i = 0; i < 6; i++)
{
var request = new DnsRequestMessage(
new DnsRequestHeader(i, DnsOpCode.Query),
new DnsQuestion("test.com", QueryType.A, QueryClass.IN));
var result = await lookup.ResolveQueryAsync(lookup.GetNextServers(), messageHandler, request, false);
Assert.False(result.HasError);
}
Assert.Equal(6, calledIps.Count);
Assert.Equal(IPAddress.Parse("127.0.0.1"), calledIps[0]);
Assert.Equal(IPAddress.Parse("127.0.0.2"), calledIps[1]);
Assert.Equal(IPAddress.Parse("127.0.0.3"), calledIps[2]);
Assert.Equal(IPAddress.Parse("127.0.0.1"), calledIps[3]);
Assert.Equal(IPAddress.Parse("127.0.0.2"), calledIps[4]);
Assert.Equal(IPAddress.Parse("127.0.0.3"), calledIps[5]);
}
public async Task Lookup_PreserveNameServerOrderAsync()
{
var lookup = new LookupClient(
new NameServer(IPAddress.Parse("127.0.0.1")),
new NameServer(IPAddress.Parse("127.0.0.2")),
new NameServer(IPAddress.Parse("127.0.0.3")))
{
// default is true
UseRandomNameServer = false
};
var calledIps = new List <IPAddress>();
var messageHandler = new TestMessageHandler((ip, req) =>
{
calledIps.Add(ip.Address);
return(new DnsResponseMessage(
new DnsResponseHeader(1, (int)DnsResponseCode.NoError, 0, 0, 0, 0),
0));
});
// calling multiple times will always use the first server when it returns NoError.
// No other servers should be called
for (var i = 0; i < 3; i++)
{
var request = new DnsRequestMessage(
new DnsRequestHeader(i, DnsOpCode.Query),
new DnsQuestion("test.com", QueryType.A, QueryClass.IN));
var result = await lookup.ResolveQueryAsync(lookup.GetNextServers(), messageHandler, request, false);
Assert.False(result.HasError);
}
Assert.Equal(3, calledIps.Count);
Assert.Equal(IPAddress.Parse("127.0.0.1"), calledIps[0]);
Assert.Equal(IPAddress.Parse("127.0.0.1"), calledIps[1]);
Assert.Equal(IPAddress.Parse("127.0.0.1"), calledIps[2]);
}
public async Task Lookup_RetryOnDnsErrorAsync()
{
var lookup = new LookupClient(
new NameServer(IPAddress.Parse("127.0.0.1")),
new NameServer(IPAddress.Parse("127.0.0.2")),
new NameServer(IPAddress.Parse("127.0.0.3")),
new NameServer(IPAddress.Parse("127.0.0.4")),
new NameServer(IPAddress.Parse("127.0.0.5")),
new NameServer(IPAddress.Parse("127.0.0.6")),
new NameServer(IPAddress.Parse("127.0.0.7")))
{
EnableAuditTrail = true,
ContinueOnDnsError = true
};
var calledIps = new List <IPAddress>();
var messageHandler = new TestMessageHandler((ip, req) =>
{
calledIps.Add(ip.Address);
return(new DnsResponseMessage(
new DnsResponseHeader(1, (int)DnsResponseCode.NotExistentDomain, 0, 0, 0, 0),
0));
});
var request = new DnsRequestMessage(
new DnsRequestHeader(0, DnsOpCode.Query),
new DnsQuestion("test.com", QueryType.A, QueryClass.IN));
var result = await lookup.ResolveQueryAsync(lookup.GetNextServers(), messageHandler, request, false);
// no exception but error in the response after calling all 3 endpoints!
Assert.True(result.HasError);
Assert.Equal(DnsResponseCode.NotExistentDomain, result.Header.ResponseCode);
// ensure the client tried all the configured endpoints
Assert.Equal(7, calledIps.Count);
}
