public async Task TestQuery()
{
using var tokenSource = new CancellationTokenSource(TimeSpan.FromMilliseconds(500));
var endpoint = GenerateEndPoint();
// Create a real upstream DNS client to serve the request (todo: mock this)
using var upstream = new DnsUdpClient(IPAddress.Parse("1.1.1.1"));
// Create a loopback server
using var server = new DnsUdpServer(endpoint, upstream);
// Start recieving
using var receiveTask = server.Listen(tokenSource.Token);
// Create a loopback DNS client to talk to the server
using var client = new DnsUdpClient(endpoint);
try
{
var query = DnsQueryFactory.CreateQuery("google.com");
// Send a DNS request to the server, verify the results
var response = await client.Query(query, tokenSource.Token);
Assert.Equal(query.Id, response.Header.Id);
Assert.Equal(query.Host, response.Header.Host);
Assert.True(response.Answers.Count > 0);
}
finally
{
tokenSource.Cancel();
await receiveTask;
}
}
private void buttonClientSend_Click(object sender, EventArgs e)
{
string errorMessage;
IPAddress serverAddr;
Cursor = Cursors.WaitCursor;
buttonClientSend.Enabled = false;
if (!ValidateServerText(textBoxClientServer.Text, out errorMessage))
{
errorProvider1.SetError(textBoxClientServer, errorMessage);
return;
}
try
{
// resolve server name by System.Net.Dns
serverAddr = System.Net.Dns.GetHostAddresses(textBoxClientServer.Text.Trim()).First();
}
catch (SocketException)
{
errorProvider1.SetError(textBoxClientServer, "Server name cannot be resolved.");
return;
}
try
{
IDnsClient client;
if (radioButtonClientTCP.Checked)
{
client = new DnsTcpClient();
}
else
{
client = new DnsUdpClient();
}
Request request = new Request(
(ushort)DateTime.Now.Ticks,
checkBoxClientRD.Checked,
(OPCODE)Enum.Parse(typeof(OPCODE), comboBoxClientOPCODE.SelectedValue.ToString()),
new Question(
textBoxClientQNAME.Text.Trim(),
(QTYPE)Enum.Parse(typeof(QTYPE), comboBoxClientQTYPE.SelectedValue.ToString()),
(QCLASS)Enum.Parse(typeof(QCLASS), comboBoxClientQCLASS.SelectedValue.ToString())));
labelClientResponse.Text = String.Empty;
textBoxClientResponse.Text = String.Empty;
client.Connect(serverAddr);
client.BeginProcess(request, new AsyncCallback(OnClientResponseReceived),
new ClientAsyncState {
Client = client, Request = request, Server = serverAddr
});
//try
//{
// client.Connect(serverAddr);
// DnsClient.Response response = client.LookUp(request);
// labelClientResponse.Text = String.Format("{0}: {1} from [{2}] in {3}ms",
// (response.Header.AA ? "Authoritative Response" : "Non-Authoritative Response"),
// response.Header.RCODE.ToString(),
// serverAddr.ToString(),
// response.Timestamp.Subtract(request.Timestamp).TotalMilliseconds);
// StringBuilder result = new StringBuilder();
// RenderResponse(response, result);
// textBoxClientResponse.Text = result.ToString();
//}
//finally
//{
// Cursor = Cursors.Default;
// buttonClientSend.Enabled = true;
//}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString(), "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
public void TestCleanup()
{
this.client?.Dispose();
this.client = null;
}
public void TestInitialize()
{
this.client = new DnsUdpClient();
}
static void Main(string[] args)
{
try
{
File.Delete(filename);
bool interactive = false;
NameServer selected = null;
while (true)
{
if (File.Exists(filename))
{
using (DnsUdpClient client = new DnsUdpClient())
{
client.Client.SetSocketOption(System.Net.Sockets.SocketOptionLevel.Socket, System.Net.Sockets.SocketOptionName.ReceiveTimeout, 1000);
client.LogMessageCreated += new LogMessageEventHandler(OnLogMessage);
ResolutionIterator iterator = DeSerializeObject <ResolutionIterator>(filename);
iterator.Resolver.Connect(client);
if (iterator.MoveNext(selected))
{
Console.WriteLine();
ResolutionResult result = iterator.Current;
//Console.WriteLine("Response from {0} - chosen from {1} authorities", result.Authorities.Selected.Name, result.Authorities.ZoneName);
//foreach (NameServer ns in result.Authorities)
//{
// Console.WriteLine(" {0}", ns);
//}
Console.WriteLine("Took {0}ms:", result.Duration.TotalMilliseconds);
RenderResponse(result.Response);
if (interactive)
{
selected = null;
if (result.NextAuthorities != null)
{
Console.WriteLine();
Console.WriteLine("Next authorities:");
int i = 1;
foreach (NameServer ns in result.NextAuthorities)
{
Console.WriteLine(" ({0}) {1}", i, ns.ToString());
i++;
}
while (true)
{
Console.Write("Select next authority or ENTER for random: ");
int s;
string choice = Console.ReadLine();
if (!String.IsNullOrEmpty(choice))
{
if (int.TryParse(choice, out s))
{
if (s >= 1 && s <= result.NextAuthorities.Count)
{
selected = result.NextAuthorities[s - 1];
break;
}
}
}
else
{
break;
}
}
}
}
SerializeObject <ResolutionIterator>(filename, iterator);
Console.WriteLine("====================================");
}
else
{
Console.WriteLine("finished.");
File.Delete(filename);
}
}
}
else
{
DnsDomain domain = null;
QTYPE question;
try
{
Console.Write("enter name: ");
domain = DnsDomain.Parse(Console.ReadLine().Trim());
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
goto next;
}
try
{
Console.Write("enter question: ");
question = (QTYPE)Enum.Parse(typeof(QTYPE), Console.ReadLine().Trim(), true);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
goto next;
}
Console.WriteLine("OK: {0} IN {1}", domain, question.ToString());
DomainResolver resolver = new DomainResolver(Options.Default, domain);
ResolutionIterator iterator = resolver.GetIterator(question);
iterator.LogMessageCreated += new LogMessageEventHandler(OnLogMessage);
SerializeObject <ResolutionIterator>(filename, iterator);
}
next:
Console.WriteLine();
Console.WriteLine("type 'q' to quit, ENTER to continue.");
ConsoleKeyInfo ck = Console.ReadKey();
if (ck.KeyChar == 'q')
{
break;
}
}
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
}
public async Task TestLookupTimeout()
{
// Reserved - see https://en.wikipedia.org/wiki/Reserved_IP_addresses
using var client = new DnsUdpClient(new NullLogger <DnsUdpClient>(), IPAddress.Parse("192.88.99.0"));
await Assert.ThrowsAsync <DnsClientTimeoutException>(() => client.Query(DnsQueryFactory.CreateQuery("alanedwardes.com"), CancellationToken.None));
}
public async Task TestLookupWithGoogle(string domain, DnsQueryType type)
{
using var client = new DnsUdpClient(new NullLogger <DnsUdpClient>(), IPAddress.Parse("8.8.8.8"));
await client.RunQuery(domain, type);
}
public async Task TestLookupWithCloudFlare(string domain, DnsQueryType type)
{
using var client = new DnsUdpClient(new NullLogger <DnsUdpClient>(), IPAddress.Parse("1.1.1.1"));
await client.RunQuery(domain, type, type == DnsQueryType.ANY?DnsResponseCode.NotImp : DnsResponseCode.NoError);
}
/// <summary>
/// Resolves a DNS name.
/// </summary>
/// <param name="Name">Domain Name to resolve</param>
/// <param name="TYPE">Resource Record Type of interest.</param>
/// <param name="ExceptionType">If no answer of type <paramref name="TYPE"/> is found, records of this type can also be accepted.</param>
/// <param name="CLASS">Resource Record Class of interest.</param>
/// <returns>Answer to the query</returns>
/// <exception cref="IOException">If the domain name could not be resolved for the TYPE and CLASS provided.</exception>
public static async Task <ResourceRecord[]> Resolve(string Name, QTYPE TYPE,
TYPE?ExceptionType, QCLASS CLASS)
{
LinkedList <KeyValuePair <string, IPEndPoint> > Backup = null;
TYPE? ExpectedType;
IPEndPoint Destination = null;
string LastName = null;
int Timeout = 2000; // Local timeout
if (Enum.TryParse <TYPE>(TYPE.ToString(), out TYPE T))
{
ExpectedType = T;
}
else
{
ExpectedType = null;
}
lock (synchObject)
{
if (nestingDepth == 0 && networkChanged)
{
networkChanged = false;
client?.Dispose();
client = null;
}
if (client is null)
{
client = new DnsUdpClient();
}
nestingDepth++;
}
try
{
while (true)
{
DnsResponse Response = null;
DnsMessage Message;
if (LastName is null || LastName != Name)
{
LastName = Name;
try
{
Response = await Database.FindFirstDeleteRest <DnsResponse>(new FilterAnd(
new FilterFieldEqualTo("Name", Name),
new FilterFieldEqualTo("Type", TYPE),
new FilterFieldEqualTo("Class", CLASS)));
if (!(Response is null) && Response.Expires <= DateTime.Now)
{
await Database.Delete(Response);
Response = null;
}
}
catch (Exception)
{
// Some inconsistency in database. Clear collection to get fresh set of DNS entries.
await Database.Clear("DnsCache");
Response = null;
}
}
if (Response is null)
{
try
{
Message = await client.SendRequestAsync(OpCode.Query, true, new Question[]
{
new Question(Name, TYPE, CLASS)
}, Destination, Timeout);
switch (Message.RCode)
{
case RCode.NXDomain:
throw new ArgumentException("Domain name does not exist.", nameof(Name));
}
}
catch (TimeoutException)
{
Message = null;
}
if (Message is null || Message.RCode != RCode.NoError)
{
Destination = await NextDestination(Backup);
if (Destination is null)
{
throw new IOException("Unable to resolve DNS query.");
}
continue; // Check an alternative
}
uint Ttl = 60 * 60 * 24 * 30; // Maximum TTL = 30 days
Response = new DnsResponse()
{
Name = Name,
Type = TYPE,
Class = CLASS,
Answer = CheckTtl(ref Ttl, Message.Answer),
Authority = CheckTtl(ref Ttl, Message.Authority),
Additional = CheckTtl(ref Ttl, Message.Additional)
};
Response.Expires = DateTime.Now.AddSeconds(Ttl);
await Database.Insert(Response);
}
string CName = null;
if (!(Response.Answer is null))
{
if (!ExpectedType.HasValue)
{
return(Response.Answer);
}
foreach (ResourceRecord RR in Response.Answer)
{
if (RR.Type == ExpectedType.Value)
{
return(Response.Answer);
}
if (CName is null && RR.Type == Enumerations.TYPE.CNAME && RR is CNAME CNAME)
{
CName = CNAME.Name2;
}
}
if (ExceptionType.HasValue)
{
foreach (ResourceRecord RR in Response.Answer)
{
if (RR.Type == ExceptionType.Value)
{
return(Response.Answer);
}
}
}
if (!(CName is null))
{
Name = CName;
Backup = null;
continue;
}
}
if (!(Response.Authority is null))
{
foreach (ResourceRecord RR in Response.Authority)
{
if (RR is NS NS)
{
string Authority = NS.Name2;
IPAddress AuthorityAddress = null;
if (!(Response.Additional is null))
{
foreach (ResourceRecord RR2 in Response.Additional)
{
if (RR2 is A A)
{
AuthorityAddress = A.Address;
break;
}
else if (RR2 is AAAA AAAA)
{
AuthorityAddress = AAAA.Address;
break;
}
}
}
if (Backup is null)
{
Backup = new LinkedList <KeyValuePair <string, IPEndPoint> >();
}
if (AuthorityAddress is null)
{
Backup.AddLast(new KeyValuePair <string, IPEndPoint>(Authority, null));
}
else
{
Backup.AddLast(new KeyValuePair <string, IPEndPoint>(null, new IPEndPoint(AuthorityAddress, DefaultDnsPort)));
}
}
}
}
Destination = await NextDestination(Backup);
if (Destination is null)
{
throw new IOException("Unable to resolve DNS query.");
}
Timeout = 5000;
}
}
finally
{
lock (synchObject)
{
nestingDepth--;
}
}
}
