Logging communication using LogWriter 

Communication logs are very useful when troubleshooting issues at the HTTP protocol on communication level. Whenever you run into a problem, a log makes it possible to see what is going on.

To start logging, just add the following line into your code (just after creating the TlsClientSocket object):

// create an instance of TlsClientSocket
// ...

// start logging to a file
socket.LogWriter = new Rebex.FileLogWriter(@"C:\MyData\log.txt");

A sample log file:

2020-02-20 12:34:56.011 INFO TlsClientSocket(1)[15] Info: Platform: Windows 6.2.9200 32-bit; CLR: 4.0.30319.42000
2020-02-20 12:34:56.011 DEBUG TlsClientSocket(1)[15] Info: Culture: en; Windows-1250
2020-02-20 12:34:56.011 INFO TlsClientSocket(1)[15] Info: Resolving 'test.rebex.net'.
2020-02-20 12:34:56.014 INFO TlsClientSocket(1)[15] Info: Connecting to 10.0.0.42:443 using TlsClientSocket.
2020-02-20 12:34:56.015 DEBUG TlsClientSocket(1)[15] Info: Connection established (socket #3841916).
2020-02-20 12:34:56.015 DEBUG TlsClientSocket(1)[15] TLS: Using modern transport layer.
2020-02-20 12:34:56.018 INFO TlsClientSocket(1)[15] TLS: Starting TLS negotiation.
2020-02-20 12:34:56.018 DEBUG TlsClientSocket(1)[15] TLS: Using TLS 1.3 core.
2020-02-20 12:34:56.035 DEBUG TlsClientSocket(1)[18] TLS: HandshakeMessage:ClientHello was sent.
2020-02-20 12:34:56.047 DEBUG TlsClientSocket(1)[21] TLS: HandshakeMessage:ServerHello was received.
2020-02-20 12:34:56.154 INFO TlsClientSocket(1)[21] TLS: Negotiating TLS 1.3, ECDH with secp256r1, AES with 256-bit key in GCM mode, SHA384.
2020-02-20 12:34:56.180 DEBUG TlsClientSocket(1)[18] TLS: CipherSpec:ChangeCipherSpec was received.
2020-02-20 12:34:56.189 DEBUG TlsClientSocket(1)[14] TLS: HandshakeMessage:EncryptedExtensions was received.
2020-02-20 12:34:56.213 DEBUG TlsClientSocket(1)[30] TLS: HandshakeMessage:Certificate was received.
2020-02-20 12:34:56.217 DEBUG TlsClientSocket(1)[18] TLS: HandshakeMessage:CertificateVerify was received.
2020-02-20 12:34:56.226 DEBUG TlsClientSocket(1)[30] TLS: Verifying server certificate ('CN=test.rebex.net, O=Rebex').
2020-02-20 12:34:56.226 DEBUG TlsClientSocket(1)[30] TLS: Certificate verification result: Accept.
2020-02-20 12:34:56.227 DEBUG TlsClientSocket(1)[30] TLS: Verifying server key exchange signature.
2020-02-20 12:34:56.241 DEBUG TlsClientSocket(1)[21] TLS: HandshakeMessage:Finished was received.
2020-02-20 12:34:56.286 DEBUG TlsClientSocket(1)[18] TLS: CipherSpec:ChangeCipherSpec was sent.
2020-02-20 12:34:56.287 INFO TlsClientSocket(1)[10] TLS: Connection secured using cipher: TLS 1.3, ephemeral ECDH, AES with 256-bit key in GCM mode, AEAD.
2020-02-20 12:34:56.288 DEBUG TlsClientSocket(1)[26] TLS: HandshakeMessage:Finished was sent.

Log verbosity levels 

There are several levels of log verbosity:

• Error - logs error messages only
• Info - default level; logs important informative messages as well
• Debug - logs all messages useful for debugging purposes
• Verbose - very detailed log for advanced analysis; logs content of communication packets
  Warning: At the Verbose level, user credentials are written to the log as well.

To specify a log level, just pass an argument to FileLogWriter's constructor:

// start logging to a file at debug level
socket.LogWriter = new Rebex.FileLogWriter(
    @"C:\MyData\log.txt", Rebex.LogLevel.Debug);

Built-in log writers 

Text file

To log into a text file, use FileLogWriter:

// start logging to a file at debug level
socket.LogWriter = new Rebex.FileLogWriter(
    @"C:\MyData\log.txt", Rebex.LogLevel.Debug);

.NET trace listener

To log to .NET Trace Listeners, use TraceLogWriter:

// start logging to subscribed trace listeners at debug level
socket.LogWriter = new Rebex.TraceLogWriter(Rebex.LogLevel.Debug);

Standard output stream

To log to the standard output stream, use ConsoleLogWriter:

// start logging to the standard output stream at debug level
socket.LogWriter = new Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug);

Logging to multiple log writers

To log to more log writers at the same time, use TeeLogWriter:

var consoleLogWriter = new Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug);
var fileLogWriter = new Rebex.FileLogWriter(@"C:\MyData\log.txt", Rebex.LogLevel.Info);

// start logging to both console and file log writers
socket.LogWriter = new Rebex.TeeLogWriter(consoleLogWriter, fileLogWriter);

Writing custom log writers 

// Sample log writer that logs to the standard error output stream
public class MyLogWriter : LogWriterBase
{
    protected override void WriteMessage(string message)
    {
        Console.Error.WriteLine("Rebex TLS: {0}", message);
    }
}