protected override byte[] QueryByTcp(IPAddress nameServer, int port, byte[] messageData, int messageLength, ref TcpClient tcpClient, ref System.IO.Stream tlsStream, out IPAddress responderAddress, out int responderPort)
{
responderAddress = nameServer;
responderPort = port == 0 ? _port : port;
if (!IsTcpEnabled)
{
return(null);
}
IPEndPoint endPoint = new IPEndPoint(nameServer, port == 0 ? _port : port);
IPAddress unferResponderAddress = responderAddress;
int unferResponderPort = responderPort;
TlsUpstreamServer tlsServer = _tlsservers.Where(t => t.IPAddress == unferResponderAddress && t.Port == unferResponderPort).FirstOrDefault();
if (tlsServer == null)
{
Trace.TraceError("Error on dns query: invalid TLS upstream server");
return(null);
}
try
{
if (tcpClient == null || (this.IsReuseTcpEnabled && !tcpClient.IsConnected()))
{
tcpClient = new TcpClient(nameServer.AddressFamily)
{
ReceiveTimeout = QueryTimeout,
SendTimeout = QueryTimeout
};
if (!tcpClient.TryConnect(endPoint, QueryTimeout))
{
return(null);
}
SslStream sslStream = new SslStream(tcpClient.GetStream(), true, new RemoteCertificateValidationCallback(tlsServer.ValidateRemoteCertificate));
tlsStream = sslStream;
try
{
sslStream.AuthenticateAsClient(tlsServer.AuthName ?? string.Empty, new X509CertificateCollection(), tlsServer.SslProtocols, false);
}
catch (Exception)
{
}
if (!sslStream.IsAuthenticated)
{
Trace.TraceError("Error on dns query: invalid TLS upstream server certificate");
if (this.IsReuseTcpEnabled)
{
try
{
tlsStream.Dispose();
tcpClient.Close();
}
catch (Exception)
{
}
}
return(null);
}
}
int tmp = 0;
byte[] lengthBuffer = new byte[2];
if (messageLength > 0)
{
DnsMessageBase.EncodeUShort(lengthBuffer, ref tmp, (ushort)messageLength);
tlsStream.Write(lengthBuffer, 0, 2);
tlsStream.Write(messageData, 0, messageLength);
}
if (!TryRead(tcpClient, tlsStream, lengthBuffer, 2))
{
return(null);
}
tmp = 0;
int length = DnsMessageBase.ParseUShort(lengthBuffer, ref tmp);
byte[] resultData = new byte[length];
return(TryRead(tcpClient, tlsStream, resultData, length) ? resultData : null);
}
catch (Exception e)
{
Trace.TraceError("Error on dns query: " + e);
return(null);
}
}
/// <summary>
/// Provides a new instance with custom dns server and query timeout
/// </summary>
/// <param name="dnsServer"> The IPAddress of the dns server to use </param>
/// <param name="queryTimeout"> Query timeout in milliseconds </param>
/// <param name="port"> Server port </param>
public DnsOverTlsClient(TlsUpstreamServer dnsServer, int queryTimeout, int port = 853)
: this(new List <TlsUpstreamServer> {
dnsServer
}, queryTimeout, port)
{
}
protected async override Task <QueryResponse> QueryByTcpAsync(IPAddress nameServer, int port, byte[] messageData, int messageLength, TcpClient tcpClient, System.IO.Stream tlsStream, CancellationToken token)
{
if (!IsTcpEnabled)
{
return(null);
}
int responderPort = port == 0 ? _port : port;
TlsUpstreamServer tlsServer = _tlsservers.Where(t => t.IPAddress == nameServer && t.Port == responderPort).FirstOrDefault();
if (tlsServer == null)
{
Trace.TraceError("Error on dns query: invalid TLS upstream server");
return(null);
}
string reusableMapKey = string.Concat(nameServer, port);
if (tcpClient == null && this.IsReuseTcpEnabled)
{
if (!this.reusableTcp.ContainsKey(reusableMapKey))
{
this.reusableTcp[reusableMapKey] = new ReusableTcpConnection();
}
ReusableTcpConnection reuse = this.reusableTcp[reusableMapKey];
tcpClient = reuse.Client;
tlsStream = reuse.Stream;
this.reusableTcp[reusableMapKey].LastUsed = DateTime.UtcNow;
}
try
{
if (tcpClient == null || (this.IsReuseTcpEnabled && !tcpClient.IsConnected()))
{
tcpClient = new TcpClient(nameServer.AddressFamily)
{
ReceiveTimeout = QueryTimeout,
SendTimeout = QueryTimeout
};
if (!await tcpClient.TryConnectAsync(nameServer, responderPort, QueryTimeout, token))
{
return(null);
}
SslStream sslStream = new SslStream(tcpClient.GetStream(), true, new RemoteCertificateValidationCallback(tlsServer.ValidateRemoteCertificate));
tlsStream = sslStream;
try
{
sslStream.AuthenticateAsClient(tlsServer.AuthName ?? string.Empty, new X509CertificateCollection(), tlsServer.SslProtocols, false);
}
catch (Exception)
{
}
if (!sslStream.IsAuthenticated)
{
Trace.TraceError("Error on dns query: invalid TLS upstream server certificate");
if (this.IsReuseTcpEnabled)
{
try
{
tlsStream.Dispose();
tcpClient.Close();
}
catch (Exception)
{
}
}
return(null);
}
}
int tmp = 0;
byte[] lengthBuffer = new byte[2];
if (messageLength > 0)
{
DnsMessageBase.EncodeUShort(lengthBuffer, ref tmp, (ushort)messageLength);
await tlsStream.WriteAsync(lengthBuffer, 0, 2, token);
await tlsStream.WriteAsync(messageData, 0, messageLength, token);
}
if (!await TryReadAsync(tcpClient, tlsStream, lengthBuffer, 2, token))
{
return(null);
}
tmp = 0;
int length = DnsMessageBase.ParseUShort(lengthBuffer, ref tmp);
byte[] resultData = new byte[length];
return(await TryReadAsync(tcpClient, tlsStream, resultData, length, token) ? new QueryResponse(resultData, nameServer, tcpClient, tlsStream, responderPort) : null);
}
catch (Exception e)
{
Trace.TraceError("Error on dns query: " + e);
return(null);
}
}