315 lines
10 KiB
Python
315 lines
10 KiB
Python
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#
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# Copyright (C) 2012-2013 Red Hat, Inc.
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#
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# This copyrighted material is made available to anyone wishing to use,
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# modify, copy, or redistribute it subject to the terms and conditions of
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# the GNU General Public License v.2, or (at your option) any later version.
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# This program is distributed in the hope that it will be useful, but WITHOUT
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# ANY WARRANTY expressed or implied, including the implied warranties of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
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# Public License for more details. You should have received a copy of the
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# GNU General Public License along with this program; if not, write to the
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# Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA. Any Red Hat trademarks that are incorporated in the
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# source code or documentation are not subject to the GNU General Public
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# License and may only be used or replicated with the express permission of
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# Red Hat, Inc.
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#
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"""
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Module facilitating the work with NTP servers and NTP daemon's configuration
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"""
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import re
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import os
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import tempfile
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import shutil
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from pyanaconda.anaconda_loggers import get_module_logger
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from pyanaconda.core.async_utils import async_action_nowait
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from pyanaconda.core.i18n import N_, _
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from pyanaconda.core.constants import NTP_SERVER_TIMEOUT, NTP_SERVER_QUERY, \
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THREAD_NTP_SERVER_CHECK, NTP_SERVER_OK, NTP_SERVER_NOK
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from pyanaconda.core.signal import Signal
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from pyanaconda.core.util import execWithRedirect
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from pyanaconda.modules.common.structures.timezone import TimeSourceData
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from pyanaconda.core.threads import thread_manager
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NTP_CONFIG_FILE = "/etc/chrony.conf"
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#example line:
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#server 0.fedora.pool.ntp.org iburst
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SRV_LINE_REGEXP = re.compile(r"^\s*(server|pool)\s*([-a-zA-Z.0-9]+)\s?([a-zA-Z0-9\s]*)$")
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SRV_NOARG_OPTIONS = ["burst", "iburst", "nts", "prefer", "require", "trust", "noselect", "xleave"]
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SRV_ARG_OPTIONS = ["key", "minpoll", "maxpoll"]
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# Description of an NTP server status.
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NTP_SERVER_STATUS_DESCRIPTIONS = {
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NTP_SERVER_OK: N_("status: working"),
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NTP_SERVER_NOK: N_("status: not working"),
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NTP_SERVER_QUERY: N_("checking status")
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}
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log = get_module_logger(__name__)
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class NTPconfigError(Exception):
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"""Exception class for NTP related problems"""
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pass
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def get_ntp_server_summary(server, states):
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"""Generate a summary of an NTP server and its status.
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:param server: an NTP server
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:type server: an instance of TimeSourceData
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:param states: a cache of NTP server states
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:type states: an instance of NTPServerStatusCache
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:return: a string with a summary
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"""
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return "{} ({})".format(
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server.hostname,
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states.get_status_description(server)
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)
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def get_ntp_servers_summary(servers, states):
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"""Generate a summary of NTP servers and their states.
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:param servers: a list of NTP servers
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:type servers: a list of TimeSourceData
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:param states: a cache of NTP server states
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:type states: an instance of NTPServerStatusCache
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:return: a string with a summary
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"""
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summary = _("NTP servers:")
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for server in servers:
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summary += "\n" + get_ntp_server_summary(server, states)
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if not servers:
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summary += " " + _("not configured")
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return summary
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def ntp_server_working(server_hostname, nts_enabled):
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"""Tries to do an NTP request to the server (timeout may take some time).
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If NTS is enabled, try making a TCP connection to the NTS-KE port instead.
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:param server_hostname: a host name or an IP address of an NTP server
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:type server_hostname: string
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:return: True if the given server is reachable and working, False otherwise
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:rtype: bool
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"""
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directive = ["server", server_hostname, "iburst", "maxsamples", "1"]
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if nts_enabled:
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directive.append("nts")
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arguments = ["-Q", " ".join(directive), "-t", str(NTP_SERVER_TIMEOUT)]
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return execWithRedirect("chronyd", arguments) == 0
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def get_servers_from_config(conf_file_path=NTP_CONFIG_FILE):
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"""Get NTP servers from a configuration file.
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Goes through the chronyd's configuration file looking for lines starting
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with 'server'.
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:param conf_file_path: a path to the chronyd's configuration file
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:return: servers found in the chronyd's configuration
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:rtype: a list of TimeSourceData instances
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"""
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servers = []
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try:
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with open(conf_file_path, "r") as conf_file:
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for line in conf_file:
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match = SRV_LINE_REGEXP.match(line)
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if not match:
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continue
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server = TimeSourceData()
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server.type = match.group(1).upper()
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server.hostname = match.group(2)
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server.options = []
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words = match.group(3).lower().split()
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skip_argument = False
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for i in range(len(words)):
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if skip_argument:
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skip_argument = False
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continue
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if words[i] in SRV_NOARG_OPTIONS:
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server.options.append(words[i])
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elif words[i] in SRV_ARG_OPTIONS and i + 1 < len(words):
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server.options.append(' '.join(words[i:i+2]))
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skip_argument = True
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else:
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log.debug("Unknown NTP server option %s", words[i])
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servers.append(server)
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except OSError as e:
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msg = "Cannot open config file {} for reading ({})."
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raise NTPconfigError(msg.format(conf_file_path, e.strerror)) from e
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return servers
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def save_servers_to_config(servers, conf_file_path=NTP_CONFIG_FILE, out_file_path=None):
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"""Save NTP servers to a configuration file.
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Replaces the pools and servers defined in the chronyd's configuration file
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with the given ones. If the out_file is not None, then it is used for the
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resulting config.
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:param servers: a list of NTP servers and pools
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:type servers: a list of TimeSourceData instances
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:param conf_file_path: a path to the chronyd's configuration file
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:param out_file_path: a path to the file used for the resulting config
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"""
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temp_path = None
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try:
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old_conf_file = open(conf_file_path, "r")
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except OSError as e:
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msg = "Cannot open config file {} for reading ({})."
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raise NTPconfigError(msg.format(conf_file_path, e.strerror)) from e
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if out_file_path:
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try:
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new_conf_file = open(out_file_path, "w")
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except OSError as e:
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msg = "Cannot open new config file {} for writing ({})."
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raise NTPconfigError(msg.format(out_file_path, e.strerror)) from e
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else:
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try:
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(fields, temp_path) = tempfile.mkstemp()
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new_conf_file = os.fdopen(fields, "w")
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except OSError as e:
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msg = "Cannot open temporary file {} for writing ({})."
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raise NTPconfigError(msg.format(temp_path, e.strerror)) from e
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heading = "# These servers were defined in the installation:\n"
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# write info about the origin of the following lines
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new_conf_file.write(heading)
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# write new servers and pools
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for server in servers:
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args = [server.type.lower(), server.hostname] + server.options
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line = " ".join(args) + "\n"
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new_conf_file.write(line)
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new_conf_file.write("\n")
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# copy non-server lines from the old config and skip our heading
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for line in old_conf_file:
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if not SRV_LINE_REGEXP.match(line) and line != heading:
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new_conf_file.write(line)
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old_conf_file.close()
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new_conf_file.close()
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if not out_file_path:
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try:
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# Use copy rather then move to get the correct selinux context
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shutil.copyfile(temp_path, conf_file_path)
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os.unlink(temp_path)
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except OSError as oserr:
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msg = "Cannot replace the old config with the new one ({})."
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raise NTPconfigError(msg.format(oserr.strerror)) from oserr
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class NTPServerStatusCache(object):
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"""The cache of NTP server states."""
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def __init__(self):
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self._cache = {}
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self._changed = Signal()
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@property
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def changed(self):
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"""The status changed signal."""
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return self._changed
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def get_status(self, server):
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"""Get the status of the given NTP server.
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:param TimeSourceData server: an NTP server
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:return int: a status of the NTP server
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"""
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return self._cache.get(
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server.hostname,
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NTP_SERVER_QUERY
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)
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def get_status_description(self, server):
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"""Get the status description of the given NTP server.
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:param TimeSourceData server: an NTP server
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:return str: a status description of the NTP server
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"""
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status = self.get_status(server)
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return _(NTP_SERVER_STATUS_DESCRIPTIONS[status])
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def check_status(self, server):
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"""Asynchronously check if given NTP servers appear to be working.
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:param TimeSourceData server: an NTP server
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"""
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# Get a hostname and NTS option.
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hostname = server.hostname
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nts_enabled = "nts" in server.options
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# Reset the current status.
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self._set_status(hostname, NTP_SERVER_QUERY)
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# Start the check.
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thread_manager.add_thread(
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prefix=THREAD_NTP_SERVER_CHECK,
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target=self._check_status,
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args=(hostname, nts_enabled)
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)
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def _set_status(self, hostname, status):
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"""Set the status of the given NTP server.
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:param str hostname: a hostname of an NTP server
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:return int: a status of the NTP server
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"""
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self._cache[hostname] = status
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@async_action_nowait
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def _report_status_changed(self):
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"""Emit the status changed signal.
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Run callbacks in the context of the main loop,
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so they will not affect the running thread.
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"""
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self._changed.emit()
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def _check_status(self, hostname, nts_enabled):
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"""Check if an NTP server appears to be working.
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:param str hostname: a hostname of an NTP server
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"""
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log.debug("Checking NTP server %s", hostname)
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result = ntp_server_working(hostname, nts_enabled)
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if result:
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log.debug("NTP server %s appears to be working.", hostname)
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self._set_status(hostname, NTP_SERVER_OK)
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else:
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log.debug("NTP server %s appears not to be working.", hostname)
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self._set_status(hostname, NTP_SERVER_NOK)
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self._report_status_changed()
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