Question

I will write a SSH communicator class on Python. I have telnet communicator class and I should use functions like at telnet. Telnet communicator have read_until and read_very_eager functions.

read_until : Read until a given string is encountered or until timeout.
read_very_eager : Read everything that's possible without blocking in I/O (eager).

I couldn’t find these functions for SSH communicator. Any idea?

Answer 1

You didn’t state it in the question, but I am assuming you are using Paramiko as per the tag.

• read_until: Read until a given string is encountered or until timeout.

  This seems like a very specialized function for a particular high level task. I think you will need to implement this one. You can set a timeout using paramiko.Channel.settimeout and then read in a loop until you get either the string you want or a timeout exception.

• read_very_eager: Read everything that’s possible without blocking in I/O (eager).

  Paramiko doesn’t directly provide this, but it does provide primitives for non-blocking I/O and you can easily put this in a loop to slurp in everything that’s available on the channel. Have you tried something like this?

  channel.setblocking(True)
  resultlist = []
  while True:
      try:
          chunk = channel.recv(1024)
      except socket.timeout:
          break
      resultlist.append(chunk)
  return ''.join(resultlist)