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ansible/bin/ansible-connection
Toshio Kuratomi d834412ead Fix for persistent connection plugin on Python3 (#24431) 
Fix for persistent connection plugin on Python3.  Note that fixes are also needed to each terminal plugin.  This PR only fixes the ios terminal (as proof that this approach is workable.)  Future PRs can address the other terminal types.

* On Python3, pickle needs to work with byte strings, not text strings.
* Set the pickle protocol version to 0 because we're using a pty to feed data to the connection plugin.  A pty can't have control characters.  So we have to send ascii only.  That means
only using protocol=0 for pickling the data.
* ansible-connection isn't being used with py3 in the bug but it needs
several changes to work with python3.
* In python3, closing the pty too early causes no data to be sent.  So
leave stdin open until after we finish with the ansible-connection
process.
* Fix typo using traceback.format_exc()
* Cleanup unnecessary StringIO, BytesIO, and to_bytes calls
* Modify the network_cli and terminal plugins for py3 compat.  Lots of mixing of text and byte strings that needs to be straightened out to be compatible with python3
* Documentation for the bytes<=>text strategy for terminal plugins
* Update unittests for more bytes-oriented internals

Fixes #24355
2017-05-12 09:13:51 -07:00

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#!/usr/bin/env python
# (c) 2016, Ansible, Inc. <support@ansible.com>
#
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible. If not, see <http://www.gnu.org/licenses/>.
########################################################
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
__requires__ = ['ansible']
try:
import pkg_resources
except Exception:
pass
import fcntl
import os
import shlex
import signal
import socket
import struct
import sys
import time
import traceback
import syslog
import datetime
import logging
from io import BytesIO
from ansible import constants as C
from ansible.module_utils._text import to_bytes, to_native
from ansible.module_utils.six import PY3
from ansible.module_utils.six.moves import cPickle
from ansible.playbook.play_context import PlayContext
from ansible.plugins import connection_loader
from ansible.utils.path import unfrackpath, makedirs_safe
from ansible.errors import AnsibleConnectionFailure
from ansible.utils.display import Display
def do_fork():
'''
Does the required double fork for a daemon process. Based on
http://code.activestate.com/recipes/66012-fork-a-daemon-process-on-unix/
'''
try:
pid = os.fork()
if pid > 0:
return pid
#os.chdir("/")
os.setsid()
os.umask(0)
try:
pid = os.fork()
if pid > 0:
sys.exit(0)
if C.DEFAULT_LOG_PATH != '':
out_file = open(C.DEFAULT_LOG_PATH, 'ab+')
err_file = open(C.DEFAULT_LOG_PATH, 'ab+', 0)
else:
out_file = open('/dev/null', 'ab+')
err_file = open('/dev/null', 'ab+', 0)
os.dup2(out_file.fileno(), sys.stdout.fileno())
os.dup2(err_file.fileno(), sys.stderr.fileno())
os.close(sys.stdin.fileno())
return pid
except OSError as e:
sys.exit(1)
except OSError as e:
sys.exit(1)
def send_data(s, data):
packed_len = struct.pack('!Q', len(data))
return s.sendall(packed_len + data)
def recv_data(s):
header_len = 8 # size of a packed unsigned long long
data = b""
while len(data) < header_len:
d = s.recv(header_len - len(data))
if not d:
return None
data += d
data_len = struct.unpack('!Q', data[:header_len])[0]
data = data[header_len:]
while len(data) < data_len:
d = s.recv(data_len - len(data))
if not d:
return None
data += d
return data
class Server():
def __init__(self, path, play_context):
self.path = path
self.play_context = play_context
display.display(
'creating new control socket for host %s:%s as user %s' %
(play_context.remote_addr, play_context.port, play_context.remote_user),
log_only=True
)
display.display('control socket path is %s' % path, log_only=True)
display.display('current working directory is %s' % os.getcwd(), log_only=True)
self._start_time = datetime.datetime.now()
display.display("using connection plugin %s" % self.play_context.connection, log_only=True)
self.conn = connection_loader.get(play_context.connection, play_context, sys.stdin)
self.conn._connect()
if not self.conn.connected:
raise AnsibleConnectionFailure('unable to connect to remote host %s' % self._play_context.remote_addr)
connection_time = datetime.datetime.now() - self._start_time
display.display('connection established to %s in %s' % (play_context.remote_addr, connection_time), log_only=True)
self.socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
self.socket.bind(path)
self.socket.listen(1)
signal.signal(signal.SIGALRM, self.alarm_handler)
def dispatch(self, obj, name, *args, **kwargs):
meth = getattr(obj, name, None)
if meth:
return meth(*args, **kwargs)
def alarm_handler(self, signum, frame):
'''
Alarm handler
'''
# FIXME: this should also set internal flags for other
# areas of code to check, so they can terminate
# earlier than the socket going back to the accept
# call and failing there.
#
# hooks the connection plugin to handle any cleanup
self.dispatch(self.conn, 'alarm_handler', signum, frame)
self.socket.close()
def run(self):
try:
while True:
# set the alarm, if we don't get an accept before it
# goes off we exit (via an exception caused by the socket
# getting closed while waiting on accept())
# FIXME: is this the best way to exit? as noted above in the
# handler we should probably be setting a flag to check
# here and in other parts of the code
signal.alarm(C.PERSISTENT_CONNECT_TIMEOUT)
try:
(s, addr) = self.socket.accept()
display.display('incoming request accepted on persistent socket', log_only=True)
# clear the alarm
# FIXME: potential race condition here between the accept and
# time to this call.
signal.alarm(0)
except:
break
while True:
data = recv_data(s)
if not data:
break
signal.alarm(C.DEFAULT_TIMEOUT)
rc = 255
try:
if data.startswith(b'EXEC: '):
display.display("socket operation is EXEC", log_only=True)
cmd = data.split(b'EXEC: ')[1]
(rc, stdout, stderr) = self.conn.exec_command(cmd)
elif data.startswith(b'PUT: ') or data.startswith(b'FETCH: '):
(op, src, dst) = shlex.split(to_native(data))
stdout = stderr = ''
try:
if op == 'FETCH:':
display.display("socket operation is FETCH", log_only=True)
self.conn.fetch_file(src, dst)
elif op == 'PUT:':
display.display("socket operation is PUT", log_only=True)
self.conn.put_file(src, dst)
rc = 0
except:
pass
elif data.startswith(b'CONTEXT: '):
display.display("socket operation is CONTEXT", log_only=True)
pc_data = data.split(b'CONTEXT: ', 1)[1]
pc_data = cPickle.loads(pc_data)
pc = PlayContext()
pc.deserialize(pc_data)
self.dispatch(self.conn, 'update_play_context', pc)
continue
else:
display.display("socket operation is UNKNOWN", log_only=True)
stdout = ''
stderr = 'Invalid action specified'
except:
stdout = ''
stderr = traceback.format_exc()
signal.alarm(0)
display.display("socket operation completed with rc %s" % rc, log_only=True)
send_data(s, to_bytes(rc))
send_data(s, to_bytes(stdout))
send_data(s, to_bytes(stderr))
s.close()
except Exception as e:
display.display(traceback.format_exc(), log_only=True)
finally:
# when done, close the connection properly and cleanup
# the socket file so it can be recreated
end_time = datetime.datetime.now()
delta = end_time - self._start_time
display.display('shutting down control socket, connection was active for %s secs' % delta, log_only=True)
try:
self.conn.close()
self.socket.close()
except Exception as e:
pass
os.remove(self.path)
def main():
# Need stdin as a byte stream
if PY3:
stdin = sys.stdin.buffer
else:
stdin = sys.stdin
try:
# read the play context data via stdin, which means depickling it
# FIXME: as noted above, we will probably need to deserialize the
# connection loader here as well at some point, otherwise this
# won't find role- or playbook-based connection plugins
cur_line = stdin.readline()
init_data = b''
while cur_line.strip() != b'#END_INIT#':
if cur_line == b'':
raise Exception("EOF found before init data was complete")
init_data += cur_line
cur_line = stdin.readline()
pc_data = cPickle.loads(init_data)
pc = PlayContext()
pc.deserialize(pc_data)
except Exception as e:
# FIXME: better error message/handling/logging
sys.stderr.write(traceback.format_exc())
sys.exit("FAIL: %s" % e)
ssh = connection_loader.get('ssh', class_only=True)
m = ssh._create_control_path(pc.remote_addr, pc.port, pc.remote_user)
# create the persistent connection dir if need be and create the paths
# which we will be using later
tmp_path = unfrackpath("$HOME/.ansible/pc")
makedirs_safe(tmp_path)
lk_path = unfrackpath("%s/.ansible_pc_lock" % tmp_path)
sf_path = unfrackpath(m % dict(directory=tmp_path))
# if the socket file doesn't exist, spin up the daemon process
lock_fd = os.open(lk_path, os.O_RDWR|os.O_CREAT, 0o600)
fcntl.lockf(lock_fd, fcntl.LOCK_EX)
if not os.path.exists(sf_path):
pid = do_fork()
if pid == 0:
rc = 0
try:
server = Server(sf_path, pc)
except AnsibleConnectionFailure as exc:
display.display('connecting to host %s returned an error' % pc.remote_addr, log_only=True)
display.display(str(exc), log_only=True)
rc = 1
except Exception as exc:
display.display('failed to create control socket for host %s' % pc.remote_addr, log_only=True)
display.display(traceback.format_exc(), log_only=True)
rc = 1
fcntl.lockf(lock_fd, fcntl.LOCK_UN)
os.close(lock_fd)
if rc == 0:
server.run()
sys.exit(rc)
else:
display.display('re-using existing socket for %s@%s:%s' % (pc.remote_user, pc.remote_addr, pc.port), log_only=True)
fcntl.lockf(lock_fd, fcntl.LOCK_UN)
os.close(lock_fd)
# now connect to the daemon process
# FIXME: if the socket file existed but the daemonized process was killed,
# the connection will timeout here. Need to make this more resilient.
rc = 0
while rc == 0:
data = stdin.readline()
if data == b'':
break
if data.strip() == b'':
continue
sf = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
attempts = 1
while True:
try:
sf.connect(sf_path)
break
except socket.error:
# FIXME: better error handling/logging/message here
time.sleep(C.PERSISTENT_CONNECT_INTERVAL)
attempts += 1
if attempts > C.PERSISTENT_CONNECT_RETRIES:
display.display('number of connection attempts exceeded, unable to connect to control socket', pc.remote_addr, pc.remote_user, log_only=True)
display.display('persistent_connect_interval=%s, persistent_connect_retries=%s' % (C.PERSISTENT_CONNECT_INTERVAL, C.PERSISTENT_CONNECT_RETRIES), pc.remote_addr, pc.remote_user, log_only=True)
sys.stderr.write('failed to connect to control socket')
sys.exit(255)
# send the play_context back into the connection so the connection
# can handle any privilege escalation activities
pc_data = b'CONTEXT: %s' % init_data
send_data(sf, pc_data)
send_data(sf, data.strip())
rc = int(recv_data(sf), 10)
stdout = recv_data(sf)
stderr = recv_data(sf)
sys.stdout.write(to_native(stdout))
sys.stderr.write(to_native(stderr))
sf.close()
break
sys.exit(rc)
if __name__ == '__main__':
display = Display()
main()
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