unmarshal heartbeat issue

[faxioman]

I have noticed that the unmarshal method is executed successfully on a Heartbeat frame even when the buffer does not yet have the FRAME_END.
This violates the specifications of the amqp 0.9.1 protocol. At the moment, I have solved it in this way:

count, channel, frame = unmarshal(buf)
if frame.name == Heartbeat.name and buf[-1] != FRAME_END:
    raise UnmarshalingException()

In my situation, I developed an AMQP sidecar designed to emulate a RabbitMQ broker for communication with Solace PubSub+. Prior to applying the fix, I experienced several timeout errors related to heartbeat management, particularly with Node.js clients using amqplib.

[faxioman]

I've seen that the problem only occurs with buffers that are too small. By increasing the size of the read buffer, the fix is not necessary.