Mini SSH library for python3 based on subprocess

output.txt

[niwi@vaio.niwi.be][~]% python3 subprocess_ssh.py
(0, b'Linux vaio.niwi.be 3.3.2-1-ARCH #1 SMP PREEMPT Sat Apr 14 09:48:37 CEST 2012 x86_64 Intel(R) Core(TM)2 Duo CPU T6600 @ 2.20GHz GenuineIntel GNU/Linux')
(0, b'processor\t: 0\nvendor_id\t: GenuineIntel\ncpu family\t: 6\nmodel\t\t: 23\nmodel name\t: Intel(R) Core(TM)2 Duo CPU     T6600  @ 2.20GHz\nstepping\t: 10\nmicrocode\t: 0xa07\ncpu MHz\t\t: 2193.716\ncache size\t: 2048 KB\nphysical id\t: 0\nsiblings\t: 2\ncore id\t\t: 0\ncpu cores\t: 2\napicid\t\t: 0\ninitial apicid\t: 0\nfpu\t\t: yes\nfpu_exception\t: yes\ncpuid level\t: 13\nwp\t\t: yes\nflags\t\t: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor ds_cpl est tm2 ssse3 cx16 xtpr pdcm sse4_1 xsave lahf_lm dts\nbogomips\t: 4389.24\nclflush size\t: 64\ncache_alignment\t: 64\naddress sizes\t: 36 bits physical, 48 bits virtual\npower management:\n\nprocessor\t: 1\nvendor_id\t: GenuineIntel\ncpu family\t: 6\nmodel\t\t: 23\nmodel name\t: Intel(R) Core(TM)2 Duo CPU     T6600  @ 2.20GHz\nstepping\t: 10\nmicrocode\t: 0xa07\ncpu MHz\t\t: 2193.716\ncache size\t: 2048 KB\nphysical id\t: 0\nsiblings\t: 2\ncore id\t\t: 1\ncpu cores\t: 2\napicid\t\t: 1\ninitial apicid\t: 1\nfpu\t\t: yes\nfpu_exception\t: yes\ncpuid level\t: 13\nwp\t\t: yes\nflags\t\t: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor ds_cpl est tm2 ssse3 cx16 xtpr pdcm sse4_1 xsave lahf_lm dts\nbogomips\t: 4389.24\nclflush size\t: 64\ncache_alignment\t: 64\naddress sizes\t: 36 bits physical, 48 bits virtual\npower management:\n')

subprocess_ssh.py

#!/usr/bin/env python3

import fcntl
import os
import select
from subprocess import Popen, PIPE


def non_block_read(output):
    fd = output.fileno()
    fl = fcntl.fcntl(fd, fcntl.F_GETFL)
    fcntl.fcntl(fd, fcntl.F_SETFL, fl | os.O_NONBLOCK)
    try:
        return output.read()
    except:
        return ""

class SSHClient(object):
    shell = "/bin/sh"
    ssh_path = "/usr/bin/ssh"

    started = False
    stoped = False
    returncode = None

    def __init__(self, user, host, shell=None, ssh=None): 
        self.user = user
        self.host = host

        if shell is not None:
            self.shell = shell
        
        if ssh is not None:
            self.ssh_path = ssh


    def _start_ssh_process(self):
        user_host = "{user}@{host}".format(user=self.user, host=self.host)
        self.proc = Popen([self.ssh_path, user_host, self.shell],
            stdin=PIPE, stdout=PIPE, stderr=PIPE)

        poll_result = self.proc.poll()
        if poll_result is not None:
            self.returncode = poll_result
            return self.read_stderr()
        
        self.started = True
        return None


    """
    Low level methods.
    """

    def _read(self, _file):
        output = []

        while True:
            _r, _w, _e = select.select([_file],[],[], 0.2)
            if len(_r) == 0:
                break
            
            data = non_block_read(_r[0])
            if data is None:
                break

            output.append(data)
        return b"".join(output)

    def write(self, data, encoding='utf-8'):
        if isinstance(data, str):
            data = bytes(data, encoding)

        num = self.proc.stdin.write(data)
        self.proc.stdin.flush()
        return num

    def read_stdout(self):
        return self._read(self.proc.stdout)

    def read_stderr(self):
        return self._read(self.proc.stderr)


    """
    High level methods.
    """

    def start(self):
        if self.started:
            raise Exception("Already started")

        self._start_ssh_process()

    def stop(self):
        if self.stoped:
            raise Exception("Already stoped")

        self.proc.terminate()

    def execute(self, command, encoding='ascii'):
        if isinstance(command, str):
            command = bytes(command, encoding)
        if command[-1] != b"\n":
            command = command + b"\n"

        command += b"echo $?\n"
        n = self.write(command)
        result, rcode, *o = self.read_stdout().rsplit(b"\n", 2)
        return int(rcode), result


if __name__ == '__main__':
    c = SSHClient(user="niwi", host="localhost")
    c.start()
    print(c.execute("uname -a"))
    print(c.execute("cat /proc/cpuinfo"))