public abstract Task <DnsResponseMessage> QueryAsync(IPEndPoint server, DnsRequestMessage request, CancellationToken cancellationToken,
Action <Action> cancelationCallback);
public override async Task <DnsResponseMessage> QueryAsync(
IPEndPoint server,
DnsRequestMessage request,
CancellationToken cancellationToken,
Action <Action> cancelationCallback)
{
cancellationToken.ThrowIfCancellationRequested();
UdpClient udpClient = GetNextUdpClient(server.AddressFamily);
bool mustDispose = false;
try
{
// setup timeout cancelation, dispose socket (the only way to acutally cancel the request in async...
cancelationCallback(() =>
{
#if PORTABLE
udpClient.Dispose();
#else
udpClient.Close();
#endif
});
using (var writer = new DnsDatagramWriter())
{
GetRequestData(request, writer);
await udpClient.SendAsync(writer.Data.Array, writer.Data.Count, server).ConfigureAwait(false);
}
var readSize = udpClient.Available > MaxSize ? udpClient.Available : MaxSize;
using (var memory = new PooledBytes(readSize))
{
#if PORTABLE
int received = await udpClient.Client.ReceiveAsync(new ArraySegment <byte>(memory.Buffer), SocketFlags.None).ConfigureAwait(false);
var response = GetResponseMessage(new ArraySegment <byte>(memory.Buffer, 0, received));
#else
var result = await udpClient.ReceiveAsync().ConfigureAwait(false);
var response = GetResponseMessage(new ArraySegment <byte>(result.Buffer, 0, result.Buffer.Length));
#endif
if (request.Header.Id != response.Header.Id)
{
throw new DnsResponseException("Header id missmatch.");
}
Enqueue(server.AddressFamily, udpClient);
return(response);
}
}
catch (ObjectDisposedException)
{
// we disposed it in case of a timeout request, lets indicate it actually timed out...
throw new TimeoutException();
}
catch
{
mustDispose = true;
throw;
}
finally
{
if (!_enableClientQueue || mustDispose)
{
try
{
#if PORTABLE
udpClient.Dispose();
#else
udpClient.Close();
#endif
}
catch { }
}
}
}
public abstract DnsResponseMessage Query(IPEndPoint endpoint, DnsRequestMessage request, TimeSpan timeout);
private async Task <IDnsQueryResponse> ResolveQueryAsync(DnsMessageHandler handler, DnsRequestMessage request, CancellationToken cancellationToken, Audit continueAudit = null)
{
if (request == null)
{
throw new ArgumentNullException(nameof(request));
}
var audit = continueAudit ?? new Audit();
var servers = GetNextServers();
foreach (var serverInfo in servers)
{
var tries = 0;
do
{
tries++;
try
{
cancellationToken.ThrowIfCancellationRequested();
if (EnableAuditTrail)
{
audit.StartTimer();
}
DnsResponseMessage response;
Action onCancel = () => { };
Task <DnsResponseMessage> resultTask = handler.QueryAsync(serverInfo.Endpoint, request, cancellationToken, (cancel) =>
{
onCancel = cancel;
});
if (Timeout != s_infiniteTimeout || (cancellationToken != CancellationToken.None && cancellationToken.CanBeCanceled))
{
var cts = new CancellationTokenSource(Timeout);
CancellationTokenSource linkedCts = null;
if (cancellationToken != CancellationToken.None)
{
linkedCts = CancellationTokenSource.CreateLinkedTokenSource(cts.Token, cancellationToken);
}
using (cts)
using (linkedCts)
{
response = await resultTask.WithCancellation((linkedCts ?? cts).Token, onCancel).ConfigureAwait(false);
}
}
else
{
response = await resultTask.ConfigureAwait(false);
}
if (response.Header.ResultTruncated && UseTcpFallback && !handler.GetType().Equals(typeof(DnsTcpMessageHandler)))
{
if (EnableAuditTrail)
{
audit.AuditTruncatedRetryTcp();
}
return(await ResolveQueryAsync(_tcpFallbackHandler, request, cancellationToken, audit).ConfigureAwait(false));
}
if (EnableAuditTrail)
{
audit.AuditResolveServers(_endpoints.Count);
audit.AuditResponseHeader(response.Header);
}
if (response.Header.ResponseCode != DnsResponseCode.NoError)
{
if (EnableAuditTrail)
{
audit.AuditResponseError(response.Header.ResponseCode);
}
if (ThrowDnsErrors)
{
throw new DnsResponseException(response.Header.ResponseCode);
}
}
HandleOptRecords(audit, serverInfo, response);
DnsQueryResponse queryResponse = response.AsQueryResponse(serverInfo.Clone());
if (EnableAuditTrail)
{
audit.AuditResponse(queryResponse);
audit.AuditEnd(queryResponse);
queryResponse.AuditTrail = audit.Build();
}
Interlocked.Increment(ref StaticLog.ResolveQueryCount);
Interlocked.Add(ref StaticLog.ResolveQueryTries, tries);
return(queryResponse);
}
catch (DnsResponseException ex)
{
audit.AuditException(ex);
ex.AuditTrail = audit.Build();
throw;
}
catch (SocketException ex) when(ex.SocketErrorCode == SocketError.AddressFamilyNotSupported)
{
// this socket error might indicate the server endpoint is actually bad and should be ignored in future queries.
DisableServer(serverInfo);
break;
}
catch (Exception ex) when(ex is TimeoutException || handler.IsTransientException(ex))
{
// our timeout got eventually triggered by the a task cancelation token, throw OCE instead...
if (cancellationToken.IsCancellationRequested)
{
throw new OperationCanceledException(cancellationToken);
}
DisableServer(serverInfo);
}
catch (Exception ex)
{
DisableServer(serverInfo);
var handleEx = ex;
var agg = ex as AggregateException;
if (agg != null)
{
if (agg.InnerExceptions.Any(e => e is TimeoutException || handler.IsTransientException(e)))
{
continue;
}
handleEx = agg.InnerException;
}
if (handleEx is OperationCanceledException || handleEx is TaskCanceledException)
{
if (cancellationToken.IsCancellationRequested)
{
throw new OperationCanceledException(cancellationToken);
}
continue;
}
audit.AuditException(ex);
throw new DnsResponseException("Unhandled exception", ex)
{
AuditTrail = audit.Build()
};
}
} while (tries <= Retries && !cancellationToken.IsCancellationRequested && serverInfo.Enabled);
}
throw new DnsResponseException(
DnsResponseCode.ConnectionTimeout,
$"No connection could be established to any of the following name servers: {string.Join(", ", NameServers)}.")
{
AuditTrail = audit.Build()
};
}
public override DnsResponseMessage Query(
IPEndPoint server,
DnsRequestMessage request,
TimeSpan timeout)
{
UdpClient udpClient = GetNextUdpClient(server.AddressFamily);
// -1 indicates infinite
int timeoutInMillis = timeout.TotalMilliseconds >= int.MaxValue ? -1 : (int)timeout.TotalMilliseconds;
udpClient.Client.ReceiveTimeout = timeoutInMillis;
udpClient.Client.SendTimeout = timeoutInMillis;
bool mustDispose = false;
try
{
using (var writer = new DnsDatagramWriter())
{
GetRequestData(request, writer);
udpClient.Client.SendTo(writer.Data.Array, writer.Data.Offset, writer.Data.Count, SocketFlags.None, server);
}
var readSize = udpClient.Available > MaxSize ? udpClient.Available : MaxSize;
using (var memory = new PooledBytes(readSize))
{
var received = udpClient.Client.Receive(memory.Buffer, 0, readSize, SocketFlags.None);
var response = GetResponseMessage(new ArraySegment <byte>(memory.Buffer, 0, received));
if (request.Header.Id != response.Header.Id)
{
throw new DnsResponseException("Header id missmatch.");
}
Enqueue(server.AddressFamily, udpClient);
return(response);
}
}
catch
{
mustDispose = true;
throw;
}
finally
{
if (!_enableClientQueue || mustDispose)
{
try
{
#if PORTABLE
udpClient.Dispose();
#else
udpClient.Close();
#endif
}
catch { }
}
}
}
private IDnsQueryResponse ResolveQuery(DnsMessageHandler handler, DnsRequestMessage request, Audit continueAudit = null)
{
if (request == null)
{
throw new ArgumentNullException(nameof(request));
}
var audit = continueAudit ?? new Audit();
var servers = GetNextServers();
foreach (var serverInfo in servers)
{
var tries = 0;
do
{
tries++;
try
{
if (EnableAuditTrail)
{
audit.StartTimer();
}
DnsResponseMessage response = handler.Query(serverInfo.Endpoint, request, Timeout);
if (response.Header.ResultTruncated && UseTcpFallback && !handler.GetType().Equals(typeof(DnsTcpMessageHandler)))
{
if (EnableAuditTrail)
{
audit.AuditTruncatedRetryTcp();
}
return(ResolveQuery(_tcpFallbackHandler, request, audit));
}
if (EnableAuditTrail)
{
audit.AuditResolveServers(_endpoints.Count);
audit.AuditResponseHeader(response.Header);
}
if (response.Header.ResponseCode != DnsResponseCode.NoError)
{
if (EnableAuditTrail)
{
audit.AuditResponseError(response.Header.ResponseCode);
}
if (ThrowDnsErrors)
{
throw new DnsResponseException(response.Header.ResponseCode);
}
}
HandleOptRecords(audit, serverInfo, response);
DnsQueryResponse queryResponse = response.AsQueryResponse(serverInfo.Clone());
if (EnableAuditTrail)
{
audit.AuditResponse(queryResponse);
audit.AuditEnd(queryResponse);
queryResponse.AuditTrail = audit.Build();
}
Interlocked.Increment(ref StaticLog.ResolveQueryCount);
Interlocked.Add(ref StaticLog.ResolveQueryTries, tries);
return(queryResponse);
}
catch (DnsResponseException ex)
{
audit.AuditException(ex);
ex.AuditTrail = audit.Build();
throw;
}
catch (SocketException ex) when(ex.SocketErrorCode == SocketError.AddressFamilyNotSupported)
{
// this socket error might indicate the server endpoint is actually bad and should be ignored in future queries.
DisableServer(serverInfo);
break;
}
catch (Exception ex) when(ex is TimeoutException || handler.IsTransientException(ex))
{
DisableServer(serverInfo);
}
catch (Exception ex)
{
DisableServer(serverInfo);
if (ex is OperationCanceledException || ex is TaskCanceledException)
{
// timeout
continue;
}
audit.AuditException(ex);
throw new DnsResponseException(DnsResponseCode.Unassigned, "Unhandled exception", ex)
{
AuditTrail = audit.Build()
};
}
} while (tries <= Retries && serverInfo.Enabled);
}
throw new DnsResponseException(DnsResponseCode.ConnectionTimeout, $"No connection could be established to any of the following name servers: {string.Join(", ", NameServers)}.")
{
AuditTrail = audit.Build()
};
}
public override async Task <DnsResponseMessage> QueryAsync(
IPEndPoint server,
DnsRequestMessage request,
CancellationToken cancellationToken,
Action <Action> cancelationCallback)
{
cancellationToken.ThrowIfCancellationRequested();
using (var client = new TcpClient(server.AddressFamily))
{
cancelationCallback(() =>
{
#if PORTABLE
client.Dispose();
#else
client.Close();
#endif
});
cancellationToken.ThrowIfCancellationRequested();
await client.ConnectAsync(server.Address, server.Port).ConfigureAwait(false);
using (var stream = client.GetStream())
{
// use a pooled buffer to writer the data + the length of the data later into the frist two bytes
using (var memory = new PooledBytes(DnsDatagramWriter.BufferSize + 2))
using (var writer = new DnsDatagramWriter(new ArraySegment <byte>(memory.Buffer, 2, memory.Buffer.Length - 2)))
{
GetRequestData(request, writer);
int dataLength = writer.Index;
memory.Buffer[0] = (byte)((dataLength >> 8) & 0xff);
memory.Buffer[1] = (byte)(dataLength & 0xff);
//var sendData = new byte[dataLength + 2];
//sendData[0] = (byte)((dataLength >> 8) & 0xff);
//sendData[1] = (byte)(dataLength & 0xff);
//Array.Copy(data, 0, sendData, 2, dataLength);
await stream.WriteAsync(memory.Buffer, 0, dataLength + 2, cancellationToken).ConfigureAwait(false);
await stream.FlushAsync(cancellationToken).ConfigureAwait(false);
}
int length = stream.ReadByte() << 8 | stream.ReadByte();
if (length <= 0)
{
throw new DnsResponseException("Received no answer.");
}
var resultData = new byte[length];
int bytesReceived = 0;
while (bytesReceived < length)
{
int read = await stream.ReadAsync(resultData, bytesReceived, length - bytesReceived, cancellationToken).ConfigureAwait(false);
bytesReceived += read;
if (read == 0 && bytesReceived < length)
{
// disconnected
throw new SocketException(-1);
}
}
var response = GetResponseMessage(new ArraySegment <byte>(resultData, 0, bytesReceived));
if (request.Header.Id != response.Header.Id)
{
throw new DnsResponseException("Header id missmatch.");
}
return(response);
}
}
}
private async Task <DnsResponseMessage> QueryAsyncInternal(
Stream stream,
DnsRequestMessage request,
CancellationToken cancellationToken)
{
cancellationToken.ThrowIfCancellationRequested();
// use a pooled buffer to writer the data + the length of the data later into the frist two bytes
using (var memory = new PooledBytes(DnsDatagramWriter.BufferSize + 2))
{
var writer = new DnsDatagramWriter(new ArraySegment <byte>(memory.Buffer, 2, memory.Buffer.Length - 2));
GetRequestData(request, writer);
var dataLength = writer.Index;
memory.Buffer[0] = (byte)((dataLength >> 8) & 0xff);
memory.Buffer[1] = (byte)(dataLength & 0xff);
//await client.Client.SendAsync(new ArraySegment<byte>(memory.Buffer, 0, dataLength + 2), SocketFlags.None).ConfigureAwait(false);
await stream.WriteAsync(memory.Buffer, 0, dataLength + 2, cancellationToken).ConfigureAwait(false);
await stream.FlushAsync(cancellationToken).ConfigureAwait(false);
}
if (!stream.CanRead)
{
return(null);
}
cancellationToken.ThrowIfCancellationRequested();
int length;
try
{
length = stream.ReadByte() << 8 | stream.ReadByte();
}
catch (Exception ex) when(ex is IOException || ex is SocketException)
{
return(null);
}
if (length <= 0)
{
// server signals close/disconnecting
return(null);
}
using (var memory = new PooledBytes(length))
{
var bytesReceived = 0;
var readSize = length > 4096 ? 4096 : length;
while ((bytesReceived += await stream.ReadAsync(memory.Buffer, bytesReceived, readSize).ConfigureAwait(false)) < length)
{
if (bytesReceived <= 0)
{
// disconnected
return(null);
}
if (bytesReceived + readSize > length)
{
readSize = length - bytesReceived;
if (readSize <= 0)
{
break;
}
}
}
var response = GetResponseMessage(new ArraySegment <byte>(memory.Buffer, 0, bytesReceived));
if (request.Header.Id != response.Header.Id)
{
throw new DnsResponseException("Header id mismatch.");
}
return(response);
}
}
private async Task <DnsResponseMessage> QueryAsyncInternal(TcpClient client, DnsRequestMessage request, CancellationToken cancellationToken)
{
cancellationToken.ThrowIfCancellationRequested();
var stream = client.GetStream();
// use a pooled buffer to writer the data + the length of the data later into the first two bytes
using (var memory = new PooledBytes(DnsDatagramWriter.BufferSize + 2))
using (var writer = new DnsDatagramWriter(new ArraySegment <byte>(memory.Buffer, 2, memory.Buffer.Length - 2)))
{
GetRequestData(request, writer);
int dataLength = writer.Index;
memory.Buffer[0] = (byte)((dataLength >> 8) & 0xff);
memory.Buffer[1] = (byte)(dataLength & 0xff);
//await client.Client.SendAsync(new ArraySegment<byte>(memory.Buffer, 0, dataLength + 2), SocketFlags.None).ConfigureAwait(false);
await stream.WriteAsync(memory.Buffer, 0, dataLength + 2, cancellationToken).ConfigureAwait(false);
await stream.FlushAsync(cancellationToken).ConfigureAwait(false);
}
if (!stream.CanRead)
{
return(null);
}
cancellationToken.ThrowIfCancellationRequested();
var responses = new List <DnsResponseMessage>();
do
{
int length;
try
{
//length = stream.ReadByte() << 8 | stream.ReadByte();
using (var lengthBuffer = new PooledBytes(2))
{
int bytesReceived = 0, read;
while ((bytesReceived += (read = await stream.ReadAsync(lengthBuffer.Buffer, bytesReceived, 2, cancellationToken).ConfigureAwait(false))) < 2)
{
if (read <= 0)
{
// disconnected, might retry
return(null);
}
}
length = lengthBuffer.Buffer[0] << 8 | lengthBuffer.Buffer[1];
}
}
catch (Exception ex) when(ex is IOException || ex is SocketException)
{
return(null);
}
if (length <= 0)
{
// server signals close/disconnecting
return(null);
}
using (var memory = new PooledBytes(length))
{
int bytesReceived = 0, read;
int readSize = length > 4096 ? 4096 : length;
while (!cancellationToken.IsCancellationRequested &&
(bytesReceived += (read = await stream.ReadAsync(memory.Buffer, bytesReceived, readSize, cancellationToken).ConfigureAwait(false))) < length)
{
if (read <= 0)
{
// disconnected
return(null);
}
if (bytesReceived + readSize > length)
{
readSize = length - bytesReceived;
if (readSize <= 0)
{
break;
}
}
}
DnsResponseMessage response = GetResponseMessage(new ArraySegment <byte>(memory.Buffer, 0, bytesReceived));
if (request.Header.Id != response.Header.Id)
{
throw new DnsResponseException("Header id mismatch.");
}
responses.Add(response);
}
} while (stream.DataAvailable && !cancellationToken.IsCancellationRequested);
return(DnsResponseMessage.Combine(responses));
}
public override async Task <DnsResponseMessage> QueryAsync(
IPEndPoint server,
DnsRequestMessage request,
CancellationToken cancellationToken,
Action <Action> cancelationCallback)
{
cancellationToken.ThrowIfCancellationRequested();
var udpClient = GetNextUdpClient(server.AddressFamily);
var mustDispose = false;
try
{
// setup timeout cancelation, dispose socket (the only way to acutally cancel the request in async...
cancelationCallback(() =>
{
udpClient.Close();
});
using (var pool = new PooledBytes(DnsDatagramWriter.BufferSize))
{
var writer = new DnsDatagramWriter(new ArraySegment <byte>(pool.Buffer));
GetRequestData(request, writer);
await udpClient.SendAsync(writer.Data.Array, writer.Data.Count, server).ConfigureAwait(false);
}
var result = await udpClient.ReceiveAsync().ConfigureAwait(false);
var response = GetResponseMessage(new ArraySegment <byte>(result.Buffer, 0, result.Buffer.Length));
if (request.Header.Id != response.Header.Id)
{
throw new DnsResponseException("Header id mismatch.");
}
Enqueue(server.AddressFamily, udpClient);
return(response);
}
catch (ObjectDisposedException)
{
// we disposed it in case of a timeout request, lets indicate it actually timed out...
throw new TimeoutException();
}
catch
{
mustDispose = true;
throw;
}
finally
{
if (!_enableClientQueue || mustDispose)
{
try
{
udpClient.Close();
}
catch
{
// ignored
}
}
}
}
