public override async Task <DnsDatagram> QueryAsync(DnsDatagram request, int timeout, int retries, CancellationToken cancellationToken)
{
_lastQueried = DateTime.UtcNow;
async Task <HttpRequestMessage> GetHttpRequest()
{
//serialize request
byte[] requestBuffer;
using (MemoryStream mS = new MemoryStream(32))
{
request.WriteTo(mS);
requestBuffer = mS.ToArray();
}
Uri queryUri;
if (_proxy == null)
{
if (_server.IsIPEndPointStale)
{
await _server.RecursiveResolveIPAddressAsync();
}
queryUri = new Uri(_server.DnsOverHttpEndPoint.Scheme + "://" + _server.IPEndPoint.ToString() + _server.DnsOverHttpEndPoint.PathAndQuery);
}
else
{
if (_server.IPEndPoint == null)
{
queryUri = _server.DnsOverHttpEndPoint;
}
else
{
queryUri = new Uri(_server.DnsOverHttpEndPoint.Scheme + "://" + _server.IPEndPoint.ToString() + _server.DnsOverHttpEndPoint.PathAndQuery);
}
}
HttpRequestMessage httpRequest = new HttpRequestMessage(HttpMethod.Post, queryUri);
httpRequest.Content = new ByteArrayContent(requestBuffer);
httpRequest.Content.Headers.ContentType = new MediaTypeHeaderValue("application/dns-message");
return(httpRequest);
}
//DoH wire format request
Stopwatch stopwatch = new Stopwatch();
int retry = 0;
while (retry < retries) //retry loop
{
retry++;
if (cancellationToken.IsCancellationRequested)
{
return(await Task.FromCanceled <DnsDatagram>(cancellationToken)); //task cancelled
}
stopwatch.Start();
Task <HttpResponseMessage> task = _httpClient.SendAsync(await GetHttpRequest(), cancellationToken);
using (CancellationTokenSource timeoutCancellationTokenSource = new CancellationTokenSource())
{
using (CancellationTokenRegistration ctr = cancellationToken.Register(delegate() { timeoutCancellationTokenSource.Cancel(); }))
{
if (await Task.WhenAny(task, Task.Delay(timeout, timeoutCancellationTokenSource.Token)) != task)
{
continue; //request timed out; retry
}
}
timeoutCancellationTokenSource.Cancel(); //to stop delay task
}
HttpResponseMessage httpResponse = await task;
stopwatch.Stop();
httpResponse.EnsureSuccessStatusCode();
byte[] responseBuffer = await httpResponse.Content.ReadAsByteArrayAsync(cancellationToken);
//parse response
using (MemoryStream mS = new MemoryStream(responseBuffer, false))
{
DnsDatagram response = DnsDatagram.ReadFrom(mS);
response.SetMetadata(_server, _protocol, stopwatch.Elapsed.TotalMilliseconds);
if (response.Identifier != request.Identifier)
{
throw new DnsClientResponseValidationException("Invalid response was received: query ID mismatch.");
}
if (response.Question.Count != request.Question.Count)
{
throw new DnsClientResponseValidationException("Invalid response was received: question count mismatch.");
}
for (int i = 0; i < response.Question.Count; i++)
{
if (request.Question[i].ZoneCut == null)
{
if (!response.Question[i].Name.Equals(request.Question[i].Name, StringComparison.Ordinal))
{
throw new DnsClientResponseValidationException("Invalid response was received: QNAME mismatch.");
}
if (response.Question[i].Type != request.Question[i].Type)
{
throw new DnsClientResponseValidationException("Invalid response was received: QTYPE mismatch.");
}
}
else
{
if (!response.Question[i].Name.Equals(request.Question[i].MinimizedName, StringComparison.Ordinal))
{
throw new DnsClientResponseValidationException("Invalid response was received: QNAME mismatch.");
}
if (response.Question[i].Type != request.Question[i].MinimizedType)
{
throw new DnsClientResponseValidationException("Invalid response was received: QTYPE mismatch.");
}
}
if (response.Question[i].Class != request.Question[i].Class)
{
throw new DnsClientResponseValidationException("Invalid response was received: QCLASS mismatch.");
}
}
return(response);
}
}
throw new DnsClientException("DnsClient failed to resolve the request: request timed out.");
}
public override async Task <DnsDatagram> QueryAsync(DnsDatagram request, int timeout, int retries, CancellationToken cancellationToken)
{
//serialize request
byte[] buffer = new byte[512];
MemoryStream bufferStream = new MemoryStream(buffer);
try
{
request.WriteTo(bufferStream);
}
catch (NotSupportedException)
{
throw new DnsClientException("DnsClient cannot send request of more than 512 bytes with UDP protocol.");
}
int bufferSize = (int)bufferStream.Position;
Stopwatch stopwatch = new Stopwatch();
if (_proxy == null)
{
if (_server.IsIPEndPointStale)
{
await _server.RecursiveResolveIPAddressAsync();
}
using (Socket socket = new Socket(_server.IPEndPoint.AddressFamily, SocketType.Dgram, ProtocolType.Udp))
{
stopwatch.Start();
bufferSize = await socket.UdpQueryAsync(new ArraySegment <byte>(buffer, 0, bufferSize), buffer, _server.IPEndPoint, timeout, retries, false, cancellationToken);
stopwatch.Stop();
}
}
else
{
stopwatch.Start();
bufferSize = await _proxy.UdpQueryAsync(new ArraySegment <byte>(buffer, 0, bufferSize), buffer, _server.EndPoint, timeout, retries, false, cancellationToken);
stopwatch.Stop();
}
//parse response
bufferStream.Position = 0;
bufferStream.SetLength(bufferSize);
DnsDatagram response = DnsDatagram.ReadFrom(bufferStream);
response.SetMetadata(_server, _protocol, stopwatch.Elapsed.TotalMilliseconds);
if (response.Identifier != request.Identifier)
{
throw new DnsClientResponseValidationException("Invalid response was received: query ID mismatch.");
}
if (response.Question.Count != request.Question.Count)
{
throw new DnsClientResponseValidationException("Invalid response was received: question count mismatch.");
}
for (int i = 0; i < response.Question.Count; i++)
{
if (request.Question[i].ZoneCut == null)
{
if (!response.Question[i].Name.Equals(request.Question[i].Name, StringComparison.Ordinal))
{
throw new DnsClientResponseValidationException("Invalid response was received: QNAME mismatch.");
}
if (response.Question[i].Type != request.Question[i].Type)
{
throw new DnsClientResponseValidationException("Invalid response was received: QTYPE mismatch.");
}
}
else
{
if (!response.Question[i].Name.Equals(request.Question[i].MinimizedName, StringComparison.Ordinal))
{
throw new DnsClientResponseValidationException("Invalid response was received: QNAME mismatch.");
}
if (response.Question[i].Type != request.Question[i].MinimizedType)
{
throw new DnsClientResponseValidationException("Invalid response was received: QTYPE mismatch.");
}
}
if (response.Question[i].Class != request.Question[i].Class)
{
throw new DnsClientResponseValidationException("Invalid response was received: QCLASS mismatch.");
}
}
return(response);
}
