Unhelpful exception message when clientProvidedName is too long

[loop-evgeny]

RabbitMQ .NET client 6.1.2 on .NET Core 3.1, Windows 7
RabbitMQ Server 3.7.26, Erlang 22.2.8, Ubuntu 18.04

Try to create a connection with a clientProvidedName that's too long, like this:

new ConnectionFactory {HostName = ..., UserName = ..., Password = ...}.CreateConnection(new string('x', 4000));

Expected results - either an exception message that tells me that the clientProvidedName is too long or the clientProvidedName is automatically truncated to a usable length. (The latter is probably preferable: as I understand, clientProvidedName is mostly used for troubleshooting, so most users would probably prefer for the connection to succeed.)

Actual results - exception message that gives little clue as to what's wrong:

 ---> RabbitMQ.Client.Exceptions.BrokerUnreachableException: None of the specified endpoints were reachable
 ---> RabbitMQ.Client.Exceptions.PossibleAuthenticationFailureException: Possibly caused by authentication failure
 ---> RabbitMQ.Client.Exceptions.OperationInterruptedException: The AMQP operation was interrupted: AMQP close-reason, initiated by Library, code=0, text='End of stream', classId=0, methodId=0, cause=System.IO.EndOfStreamException: Reached the end of the stream. Possible authentication failure.
   at RabbitMQ.Client.Impl.InboundFrame.ReadFrom(Stream reader, Byte[] frameHeaderBuffer)
   at RabbitMQ.Client.Impl.SocketFrameHandler.ReadFrame()
   at RabbitMQ.Client.Framing.Impl.Connection.MainLoopIteration()
   at RabbitMQ.Client.Framing.Impl.Connection.MainLoop()
   at RabbitMQ.Client.Impl.SimpleBlockingRpcContinuation.GetReply(TimeSpan timeout)
   at RabbitMQ.Client.Impl.ModelBase.ConnectionStartOk(IDictionary`2 clientProperties, String mechanism, Byte[] response, String locale)
   at RabbitMQ.Client.Framing.Impl.Connection.StartAndTune()
   --- End of inner exception stack trace ---
   at RabbitMQ.Client.Framing.Impl.Connection.StartAndTune()
   at RabbitMQ.Client.Framing.Impl.Connection.Open(Boolean insist)
   at RabbitMQ.Client.Framing.Impl.Connection..ctor(IConnectionFactory factory, Boolean insist, IFrameHandler frameHandler, String clientProvidedName)
   at RabbitMQ.Client.Framing.Impl.ProtocolBase.CreateConnection(IConnectionFactory factory, Boolean insist, IFrameHandler frameHandler, String clientProvidedName)
   at RabbitMQ.Client.ConnectionFactory.CreateConnection(IEndpointResolver endpointResolver, String clientProvidedName)
   --- End of inner exception stack trace ---
   at RabbitMQ.Client.ConnectionFactory.CreateConnection(IEndpointResolver endpointResolver, String clientProvidedName)
   at RabbitMQ.Client.ConnectionFactory.CreateConnection(String clientProvidedName)

The server logs this:

[error] <0.11030.332> closing AMQP connection <0.11030.332> (CLIENT_IP:CLIENT_PORT -> SERVER_IP:SERVER_PORT):
{handshake_error,starting,0,{amqp_error,frame_error,"type 1, all octets = <<>>: {frame_too_large,4368,4088}",none}}

... which is slightly more helpful - but not everyone has access to server logs.

[michaelklishin]

@loop-evgeny would you mind providing an example of a message that is "too long"?

Since this happens early during connection negotiation, the max frame size is not yet negotiated and so there is a default frame size that must be exceeded. Enforcing validation when the value is set is the only solution.

[loop-evgeny]

If you mean what the client generates when I call CreateConnection - I don't know how to capture that. But it should be easy to repro the problem with the one-liner above.

[michaelklishin]

If you mean what the client generates when I call CreateConnection - I don't know how to capture that. But it should be easy to repro the problem with the one-liner above.

Just FTR, with most clients the best way to capture that value is to take a traffic capture. With some (Bunny, possibly others) a tracing mode of all outgoing protocol frames would be an easier alternative.