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community.general/lib/ansible/plugins/connection/network_cli.py
Ganesh Nalawade 335a979f1d
Fix prompt mismatch issue for ios (#47004) 
* Fix prompt mismatch issue for ios

Fixes #40884 #44463

*  If the command prompt is matched check if data is
   still pending to be read from buffer.
*  This fix adds a new timer `buffer_read_timeout`
   which will be trigerred after command prompt
   is matched and data is attempted to be read from channel.
   If not data is present of channel the timer will expire
   and response we be returned to calling function.

* Fix unit test failure

* Update to make buffer timeout float

* Update doc and fix review comment

* Fix CI issues

* Update doc

* Fix review comments

* Fix review comments
2018-10-22 21:05:15 +05:30

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# (c) 2016 Red Hat Inc.
# (c) 2017 Ansible Project
# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
DOCUMENTATION = """
---
author: Ansible Networking Team
connection: network_cli
short_description: Use network_cli to run command on network appliances
description:
- This connection plugin provides a connection to remote devices over the
SSH and implements a CLI shell. This connection plugin is typically used by
network devices for sending and receiving CLi commands to network devices.
version_added: "2.3"
options:
host:
description:
- Specifies the remote device FQDN or IP address to establish the SSH
connection to.
default: inventory_hostname
vars:
- name: ansible_host
port:
type: int
description:
- Specifies the port on the remote device that listens for connections
when establishing the SSH connection.
default: 22
ini:
- section: defaults
key: remote_port
env:
- name: ANSIBLE_REMOTE_PORT
vars:
- name: ansible_port
network_os:
description:
- Configures the device platform network operating system. This value is
used to load the correct terminal and cliconf plugins to communicate
with the remote device.
vars:
- name: ansible_network_os
remote_user:
description:
- The username used to authenticate to the remote device when the SSH
connection is first established. If the remote_user is not specified,
the connection will use the username of the logged in user.
- Can be configured from the CLI via the C(--user) or C(-u) options.
ini:
- section: defaults
key: remote_user
env:
- name: ANSIBLE_REMOTE_USER
vars:
- name: ansible_user
password:
description:
- Configures the user password used to authenticate to the remote device
when first establishing the SSH connection.
vars:
- name: ansible_password
- name: ansible_ssh_pass
private_key_file:
description:
- The private SSH key or certificate file used to authenticate to the
remote device when first establishing the SSH connection.
ini:
- section: defaults
key: private_key_file
env:
- name: ANSIBLE_PRIVATE_KEY_FILE
vars:
- name: ansible_private_key_file
timeout:
type: int
description:
- Sets the connection time, in seconds, for communicating with the
remote device. This timeout is used as the default timeout value for
commands when issuing a command to the network CLI. If the command
does not return in timeout seconds, an error is generated.
default: 120
become:
type: boolean
description:
- The become option will instruct the CLI session to attempt privilege
escalation on platforms that support it. Normally this means
transitioning from user mode to C(enable) mode in the CLI session.
If become is set to True and the remote device does not support
privilege escalation or the privilege has already been elevated, then
this option is silently ignored.
- Can be configured from the CLI via the C(--become) or C(-b) options.
default: False
ini:
- section: privilege_escalation
key: become
env:
- name: ANSIBLE_BECOME
vars:
- name: ansible_become
become_method:
description:
- This option allows the become method to be specified in for handling
privilege escalation. Typically the become_method value is set to
C(enable) but could be defined as other values.
default: sudo
ini:
- section: privilege_escalation
key: become_method
env:
- name: ANSIBLE_BECOME_METHOD
vars:
- name: ansible_become_method
host_key_auto_add:
type: boolean
description:
- By default, Ansible will prompt the user before adding SSH keys to the
known hosts file. Since persistent connections such as network_cli run
in background processes, the user will never be prompted. By enabling
this option, unknown host keys will automatically be added to the
known hosts file.
- Be sure to fully understand the security implications of enabling this
option on production systems as it could create a security vulnerability.
default: False
ini:
- section: paramiko_connection
key: host_key_auto_add
env:
- name: ANSIBLE_HOST_KEY_AUTO_ADD
persistent_connect_timeout:
type: int
description:
- Configures, in seconds, the amount of time to wait when trying to
initially establish a persistent connection. If this value expires
before the connection to the remote device is completed, the connection
will fail.
default: 30
ini:
- section: persistent_connection
key: connect_timeout
env:
- name: ANSIBLE_PERSISTENT_CONNECT_TIMEOUT
persistent_command_timeout:
type: int
description:
- Configures, in seconds, the amount of time to wait for a command to
return from the remote device. If this timer is exceeded before the
command returns, the connection plugin will raise an exception and
close.
default: 10
ini:
- section: persistent_connection
key: command_timeout
env:
- name: ANSIBLE_PERSISTENT_COMMAND_TIMEOUT
vars:
- name: ansible_command_timeout
persistent_buffer_read_timeout:
type: float
description:
- Configures, in seconds, the amount of time to wait for the data to be read
from Paramiko channel after the command prompt is matched. This timeout
value ensures that command prompt matched is correct and there is no more data
left to be received from remote host.
default: 0.1
ini:
- section: persistent_connection
key: buffer_read_timeout
env:
- name: ANSIBLE_PERSISTENT_BUFFER_READ_TIMEOUT
vars:
- name: ansible_buffer_read_timeout
"""
import getpass
import json
import logging
import re
import os
import signal
import socket
import traceback
from io import BytesIO
from ansible.errors import AnsibleConnectionFailure
from ansible.module_utils.six import PY3
from ansible.module_utils.six.moves import cPickle
from ansible.module_utils.network.common.utils import to_list
from ansible.module_utils._text import to_bytes, to_text
from ansible.playbook.play_context import PlayContext
from ansible.plugins.connection import NetworkConnectionBase
from ansible.plugins.loader import cliconf_loader, terminal_loader, connection_loader
try:
from __main__ import display
except ImportError:
from ansible.utils.display import Display
display = Display()
class AnsibleCmdRespRecv(Exception):
pass
class Connection(NetworkConnectionBase):
''' CLI (shell) SSH connections on Paramiko '''
transport = 'network_cli'
has_pipelining = True
def __init__(self, play_context, new_stdin, *args, **kwargs):
super(Connection, self).__init__(play_context, new_stdin, *args, **kwargs)
self._ssh_shell = None
self._matched_prompt = None
self._matched_cmd_prompt = None
self._matched_pattern = None
self._last_response = None
self._history = list()
self._command_response = None
self._terminal = None
self.cliconf = None
self.paramiko_conn = None
if self._play_context.verbosity > 3:
logging.getLogger('paramiko').setLevel(logging.DEBUG)
if self._network_os:
self.cliconf = cliconf_loader.get(self._network_os, self)
if self.cliconf:
display.vvvv('loaded cliconf plugin for network_os %s' % self._network_os)
self._sub_plugins.append({'type': 'cliconf', 'name': self._network_os, 'obj': self.cliconf})
else:
display.vvvv('unable to load cliconf for network_os %s' % self._network_os)
else:
raise AnsibleConnectionFailure(
'Unable to automatically determine host network os. Please '
'manually configure ansible_network_os value for this host'
)
display.display('network_os is set to %s' % self._network_os, log_only=True)
def _get_log_channel(self):
name = "p=%s u=%s | " % (os.getpid(), getpass.getuser())
name += "paramiko [%s]" % self._play_context.remote_addr
return name
def get_prompt(self):
"""Returns the current prompt from the device"""
return self._matched_prompt
def exec_command(self, cmd, in_data=None, sudoable=True):
# this try..except block is just to handle the transition to supporting
# network_cli as a toplevel connection. Once connection=local is gone,
# this block can be removed as well and all calls passed directly to
# the local connection
if self._ssh_shell:
try:
cmd = json.loads(to_text(cmd, errors='surrogate_or_strict'))
kwargs = {'command': to_bytes(cmd['command'], errors='surrogate_or_strict')}
for key in ('prompt', 'answer', 'sendonly', 'newline', 'prompt_retry_check'):
if cmd.get(key) is True or cmd.get(key) is False:
kwargs[key] = cmd[key]
elif cmd.get(key) is not None:
kwargs[key] = to_bytes(cmd[key], errors='surrogate_or_strict')
return self.send(**kwargs)
except ValueError:
cmd = to_bytes(cmd, errors='surrogate_or_strict')
return self.send(command=cmd)
else:
return super(Connection, self).exec_command(cmd, in_data, sudoable)
def update_play_context(self, pc_data):
"""Updates the play context information for the connection"""
pc_data = to_bytes(pc_data)
if PY3:
pc_data = cPickle.loads(pc_data, encoding='bytes')
else:
pc_data = cPickle.loads(pc_data)
play_context = PlayContext()
play_context.deserialize(pc_data)
messages = ['updating play_context for connection']
if self._play_context.become ^ play_context.become:
if play_context.become is True:
auth_pass = play_context.become_pass
self._terminal.on_become(passwd=auth_pass)
messages.append('authorizing connection')
else:
self._terminal.on_unbecome()
messages.append('deauthorizing connection')
self._play_context = play_context
self.reset_history()
self.disable_response_logging()
return messages
def _connect(self):
'''
Connects to the remote device and starts the terminal
'''
if not self.connected:
self.paramiko_conn = connection_loader.get('paramiko', self._play_context, '/dev/null')
self.paramiko_conn._set_log_channel(self._get_log_channel())
self.paramiko_conn.set_options(direct={'look_for_keys': not bool(self._play_context.password and not self._play_context.private_key_file)})
self.paramiko_conn.force_persistence = self.force_persistence
ssh = self.paramiko_conn._connect()
host = self.get_option('host')
display.vvvv('ssh connection done, setting terminal', host=host)
self._ssh_shell = ssh.ssh.invoke_shell()
self._ssh_shell.settimeout(self.get_option('persistent_command_timeout'))
self._terminal = terminal_loader.get(self._network_os, self)
if not self._terminal:
raise AnsibleConnectionFailure('network os %s is not supported' % self._network_os)
display.vvvv('loaded terminal plugin for network_os %s' % self._network_os, host=host)
self.receive(prompts=self._terminal.terminal_initial_prompt, answer=self._terminal.terminal_initial_answer,
newline=self._terminal.terminal_inital_prompt_newline)
display.vvvv('firing event: on_open_shell()', host=host)
self._terminal.on_open_shell()
if self._play_context.become and self._play_context.become_method == 'enable':
display.vvvv('firing event: on_become', host=host)
auth_pass = self._play_context.become_pass
self._terminal.on_become(passwd=auth_pass)
display.vvvv('ssh connection has completed successfully', host=host)
self._connected = True
return self
def close(self):
'''
Close the active connection to the device
'''
# only close the connection if its connected.
if self._connected:
display.debug("closing ssh connection to device", host=self._play_context.remote_addr)
if self._ssh_shell:
display.debug("firing event: on_close_shell()")
self._terminal.on_close_shell()
self._ssh_shell.close()
self._ssh_shell = None
display.debug("cli session is now closed")
self.paramiko_conn.close()
self.paramiko_conn = None
display.debug("ssh connection has been closed successfully")
super(Connection, self).close()
def receive(self, command=None, prompts=None, answer=None, newline=True, prompt_retry_check=False, check_all=False):
'''
Handles receiving of output from command
'''
self._matched_prompt = None
self._matched_cmd_prompt = None
recv = BytesIO()
handled = False
command_prompt_matched = False
matched_prompt_window = window_count = 0
command_timeout = self.get_option('persistent_command_timeout')
self._validate_timeout_value(command_timeout, "persistent_command_timeout")
buffer_read_timeout = self.get_option('persistent_buffer_read_timeout')
self._validate_timeout_value(buffer_read_timeout, "persistent_buffer_read_timeout")
while True:
if command_prompt_matched:
try:
signal.signal(signal.SIGALRM, self._handle_buffer_read_timeout)
signal.setitimer(signal.ITIMER_REAL, buffer_read_timeout)
data = self._ssh_shell.recv(256)
signal.alarm(0)
# if data is still received on channel it indicates the prompt string
# is wrongly matched in between response chunks, continue to read
# remaining response.
command_prompt_matched = False
# restart command_timeout timer
signal.signal(signal.SIGALRM, self._handle_command_timeout)
signal.alarm(command_timeout)
except AnsibleCmdRespRecv:
return self._command_response
else:
data = self._ssh_shell.recv(256)
# when a channel stream is closed, received data will be empty
if not data:
break
recv.write(data)
offset = recv.tell() - 256 if recv.tell() > 256 else 0
recv.seek(offset)
window = self._strip(recv.read())
window_count += 1
if prompts and not handled:
handled = self._handle_prompt(window, prompts, answer, newline, False, check_all)
matched_prompt_window = window_count
elif prompts and handled and prompt_retry_check and matched_prompt_window + 1 == window_count:
# check again even when handled, if same prompt repeats in next window
# (like in the case of a wrong enable password, etc) indicates
# value of answer is wrong, report this as error.
if self._handle_prompt(window, prompts, answer, newline, prompt_retry_check, check_all):
raise AnsibleConnectionFailure("For matched prompt '%s', answer is not valid" % self._matched_cmd_prompt)
if self._find_prompt(window):
self._last_response = recv.getvalue()
resp = self._strip(self._last_response)
self._command_response = self._sanitize(resp, command)
if buffer_read_timeout == 0.0:
return self._command_response
else:
command_prompt_matched = True
def send(self, command, prompt=None, answer=None, newline=True, sendonly=False, prompt_retry_check=False, check_all=False):
'''
Sends the command to the device in the opened shell
'''
if check_all:
prompt_len = len(to_list(prompt))
answer_len = len(to_list(answer))
if prompt_len != answer_len:
raise AnsibleConnectionFailure("Number of prompts (%s) is not same as that of answers (%s)" % (prompt_len, answer_len))
try:
self._history.append(command)
self._ssh_shell.sendall(b'%s\r' % command)
if sendonly:
return
response = self.receive(command, prompt, answer, newline, prompt_retry_check, check_all)
return to_text(response, errors='surrogate_or_strict')
except (socket.timeout, AttributeError):
display.vvvv(traceback.format_exc(), host=self._play_context.remote_addr)
raise AnsibleConnectionFailure("timeout trying to send command: %s" % command.strip())
def _handle_buffer_read_timeout(self, signum, frame):
display.vvvv("Response received, triggered 'persistent_buffer_read_timeout' timer of %s seconds"
% self.get_option('persistent_buffer_read_timeout'), host=self._play_context.remote_addr)
raise AnsibleCmdRespRecv()
def _handle_command_timeout(self, signum, frame):
msg = 'command timeout triggered, timeout value is %s secs.\nSee the timeout setting options in the Network Debug and Troubleshooting Guide.'\
% self.get_option('persistent_command_timeout')
display.display(msg, log_only=True)
raise AnsibleConnectionFailure(msg)
def _strip(self, data):
'''
Removes ANSI codes from device response
'''
for regex in self._terminal.ansi_re:
data = regex.sub(b'', data)
return data
def _handle_prompt(self, resp, prompts, answer, newline, prompt_retry_check=False, check_all=False):
'''
Matches the command prompt and responds
:arg resp: Byte string containing the raw response from the remote
:arg prompts: Sequence of byte strings that we consider prompts for input
:arg answer: Sequence of Byte string to send back to the remote if we find a prompt.
A carriage return is automatically appended to this string.
:param prompt_retry_check: Bool value for trying to detect more prompts
:param check_all: Bool value to indicate if all the values in prompt sequence should be matched or any one of
given prompt.
:returns: True if a prompt was found in ``resp``. If check_all is True
will True only after all the prompt in the prompts list are matched. False otherwise.
'''
single_prompt = False
if not isinstance(prompts, list):
prompts = [prompts]
single_prompt = True
if not isinstance(answer, list):
answer = [answer]
prompts_regex = [re.compile(r, re.I) for r in prompts]
for index, regex in enumerate(prompts_regex):
match = regex.search(resp)
if match:
# if prompt_retry_check is enabled to check if same prompt is
# repeated don't send answer again.
if not prompt_retry_check:
prompt_answer = answer[index] if len(answer) > index else answer[0]
self._ssh_shell.sendall(b'%s' % prompt_answer)
if newline:
self._ssh_shell.sendall(b'\r')
self._matched_cmd_prompt = match.group()
if check_all and prompts and not single_prompt:
prompts.pop(0)
answer.pop(0)
return False
return True
return False
def _sanitize(self, resp, command=None):
'''
Removes elements from the response before returning to the caller
'''
cleaned = []
for line in resp.splitlines():
if (command and line.strip() == command.strip()) or self._matched_prompt.strip() in line:
continue
cleaned.append(line)
return b'\n'.join(cleaned).strip()
def _find_prompt(self, response):
'''Searches the buffered response for a matching command prompt
'''
errored_response = None
is_error_message = False
for regex in self._terminal.terminal_stderr_re:
if regex.search(response):
is_error_message = True
# Check if error response ends with command prompt if not
# receive it buffered prompt
for regex in self._terminal.terminal_stdout_re:
match = regex.search(response)
if match:
errored_response = response
self._matched_pattern = regex.pattern
self._matched_prompt = match.group()
break
if not is_error_message:
for regex in self._terminal.terminal_stdout_re:
match = regex.search(response)
if match:
self._matched_pattern = regex.pattern
self._matched_prompt = match.group()
if not errored_response:
return True
if errored_response:
raise AnsibleConnectionFailure(errored_response)
return False
def _validate_timeout_value(self, timeout, timer_name):
if timeout < 0:
raise AnsibleConnectionFailure("'%s' timer value '%s' is invalid, value should be greater than or equal to zero." % (timer_name, timeout))
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