zonemgr.py.in

#!@PYTHON@

# Copyright (C) 2010  Internet Systems Consortium.
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SYSTEMS CONSORTIUM
# DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
# INTERNET SYSTEMS CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
# FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
# NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
# WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

"""
This file implements the Secondary Manager program.

The secondary manager is one of the co-operating processes
of BIND10, which keeps track of timers and other information
necessary for BIND10 to act as a slave.
"""

import sys; sys.path.append ('@@PYTHONPATH@@')
import os
import time
import signal
import isc
import random
import threading
import select
import socket
import errno
from isc.datasrc import sqlite3_ds
from optparse import OptionParser, OptionValueError
from isc.config.ccsession import *

# If B10_FROM_BUILD is set in the environment, we use data files
# from a directory relative to that, otherwise we use the ones
# installed on the system
if "B10_FROM_BUILD" in os.environ:
    SPECFILE_PATH = os.environ["B10_FROM_BUILD"] + "/src/bin/zonemgr"
    AUTH_SPECFILE_PATH = os.environ["B10_FROM_BUILD"] + "/src/bin/auth"
else:
    PREFIX = "@prefix@"
    DATAROOTDIR = "@datarootdir@"
    SPECFILE_PATH = "@datadir@/@PACKAGE@".replace("${datarootdir}", DATAROOTDIR).replace("${prefix}", PREFIX)
    AUTH_SPECFILE_PATH = SPECFILE_PATH

SPECFILE_LOCATION = SPECFILE_PATH + "/zonemgr.spec"
AUTH_SPECFILE_LOCATION = AUTH_SPECFILE_PATH + "/auth.spec"

__version__ = "BIND10"

# define module name
XFRIN_MODULE_NAME = 'Xfrin'
AUTH_MODULE_NAME = 'Auth'

# define command name
ZONE_XFRIN_FAILED_COMMAND = 'zone_xfrin_failed'
ZONE_XFRIN_SUCCESS_COMMAND = 'zone_new_data_ready'
ZONE_REFRESH_COMMAND = 'refresh_from_zonemgr'
ZONE_NOTIFY_COMMAND = 'notify'

# define zone state
ZONE_OK = 0
ZONE_REFRESHING = 1
ZONE_EXPIRED = 2

# smallest refresh timeout
LOWERBOUND_REFRESH = 10
# smallest retry timeout
LOWERBOUND_RETRY = 5
# max zone transfer timeout
MAX_TRANSFER_TIMEOUT = 14400

# offsets of fields in the SOA RDATA
REFRESH_OFFSET = 3
RETRY_OFFSET = 4
EXPIRED_OFFSET = 5

# verbose mode
VERBOSE_MODE = False

def log_msg(msg):
    if VERBOSE_MODE:
        sys.stdout.write("[b10-zonemgr] %s\n" % str(msg))

class ZonemgrException(Exception):
    pass

class ZonemgrRefresh:
    """This class will maintain and manage zone refresh info.
    It also provides methods to keep track of zone timers and 
    do zone refresh. 
    Zone timers can be started by calling run_timer(), and it 
    can be stopped by calling shutdown() in another thread.

    """

    def __init__(self, cc, db_file, slave_socket):
        self._cc = cc
        self._check_sock = slave_socket 
        self._db_file = db_file
        self._zonemgr_refresh_info = {} 
        self._build_zonemgr_refresh_info()
        self._running = False
    
    def _random_jitter(self, max, jitter):
        """Imposes some random jitters for refresh and
        retry timers to avoid many zones need to do refresh
        at the same time. 
        The value should be between (max - jitter) and max.
        """
        if 0 == jitter:
            return max
        return random.uniform(max - jitter, max)

    def _get_current_time(self):
        return time.time()

    def _set_zone_timer(self, zone_name_class, max, jitter):
        """Set zone next refresh time."""
        self._set_zone_next_refresh_time(zone_name_class, self._get_current_time() + \
                                            self._random_jitter(max, jitter))

    def _set_zone_refresh_timer(self, zone_name_class):
        """Set zone next refresh time after zone refresh success.
           now + refresh*3/4 <= next_refresh_time <= now + refresh
           """
        zone_refresh_time = float(self._get_zone_soa_rdata(zone_name_class).split(" ")[REFRESH_OFFSET])
        zone_refresh_time = max(LOWERBOUND_REFRESH, zone_refresh_time)
        self._set_zone_timer(zone_name_class, zone_refresh_time, (1 * zone_refresh_time) / 4)

    def _set_zone_retry_timer(self, zone_name_class):
        """Set zone next refresh time after zone refresh fail.
           now + retry*3/4 <= next_refresh_time <= now + retry
           """
        zone_retry_time = float(self._get_zone_soa_rdata(zone_name_class).split(" ")[RETRY_OFFSET])
        zone_retry_time = max(LOWERBOUND_RETRY, zone_retry_time)
        self._set_zone_timer(zone_name_class, zone_retry_time, (1 * zone_retry_time) / 4)

    def _set_zone_notify_timer(self, zone_name_class):
        """Set zone next refresh time after receiving notify
           next_refresh_time = now 
        """
        self._set_zone_timer(zone_name_class, 0, 0)

    def _zone_not_exist(self, zone_name_class):
        """ Zone doesn't belong to zonemgr"""
        if zone_name_class in self._zonemgr_refresh_info.keys():
            return False
        return True

    def zone_refresh_success(self, zone_name_class):
        """Update zone info after zone refresh success"""
        if (self._zone_not_exist(zone_name_class)):
            raise ZonemgrException("[b10-zonemgr] Zone (%s, %s) doesn't "
                                   "belong to zonemgr" % zone_name_class)
            return
        self.zonemgr_reload_zone(zone_name_class)
        self._set_zone_refresh_timer(zone_name_class)
        self._set_zone_state(zone_name_class, ZONE_OK)
        self._set_zone_last_refresh_time(zone_name_class, self._get_current_time())

    def zone_refresh_fail(self, zone_name_class):
        """Update zone info after zone refresh fail"""
        if (self._zone_not_exist(zone_name_class)):
            raise ZonemgrException("[b10-zonemgr] Zone (%s, %s) doesn't "
                                   "belong to zonemgr" % zone_name_class)
            return
        self._set_zone_state(zone_name_class, ZONE_OK)
        self._set_zone_retry_timer(zone_name_class)

    def zone_handle_notify(self, zone_name_class, master):
        """Handle zone notify"""
        if (self._zone_not_exist(zone_name_class)):
            raise ZonemgrException("[b10-zonemgr] Notified zone (%s, %s) "
                                   "doesn't belong to zonemgr" % zone_name_class)
            return
        self._set_zone_notifier_master(zone_name_class, master)
        self._set_zone_notify_timer(zone_name_class)

    def zonemgr_reload_zone(self, zone_name_class):
        """ Reload a zone."""
        zone_soa = sqlite3_ds.get_zone_soa(str(zone_name_class[0]), self._db_file)
        self._zonemgr_refresh_info[zone_name_class]["zone_soa_rdata"] = zone_soa[7]

    def zonemgr_add_zone(self, zone_name_class):
        """ Add a zone into zone manager."""
        zone_info = {}
        zone_soa = sqlite3_ds.get_zone_soa(str(zone_name_class[0]), self._db_file)
        if not zone_soa:
            raise ZonemgrException("[b10-zonemgr] zone (%s, %s) doesn't have soa." % zone_name_class)
        zone_info["zone_soa_rdata"] = zone_soa[7]
        zone_info["zone_state"] = ZONE_OK
        zone_info["last_refresh_time"] = self._get_current_time() 
        zone_info["next_refresh_time"] = self._get_current_time() + \
                                         float(zone_soa[7].split(" ")[REFRESH_OFFSET])
        self._zonemgr_refresh_info[zone_name_class] = zone_info

    def _build_zonemgr_refresh_info(self):
        """ Build zonemgr refresh info map."""
        log_msg("Start loading zone into zonemgr.")
        for zone_name, zone_class in sqlite3_ds.get_zones_info(self._db_file):
            zone_name_class = (zone_name, zone_class)
            self.zonemgr_add_zone(zone_name_class)
        log_msg("Finish loading zone into zonemgr.")

    def _zone_is_expired(self, zone_name_class):
        """Judge whether a zone is expired or not."""
        zone_expired_time = float(self._get_zone_soa_rdata(zone_name_class).split(" ")[EXPIRED_OFFSET])
        zone_last_refresh_time = self._get_zone_last_refresh_time(zone_name_class)
        if (ZONE_EXPIRED == self._get_zone_state(zone_name_class) or
            zone_last_refresh_time + zone_expired_time <= self._get_current_time()):
            return True

        return False

    def _get_zone_soa_rdata(self, zone_name_class):
        return self._zonemgr_refresh_info[zone_name_class]["zone_soa_rdata"]

    def _get_zone_last_refresh_time(self, zone_name_class):
        return self._zonemgr_refresh_info[zone_name_class]["last_refresh_time"]

    def _set_zone_last_refresh_time(self, zone_name_class, time):
        self._zonemgr_refresh_info[zone_name_class]["last_refresh_time"] = time

    def _get_zone_notifier_master(self, zone_name_class):
        if ("notify_master" in self._zonemgr_refresh_info[zone_name_class].keys()):
            return self._zonemgr_refresh_info[zone_name_class]["notify_master"] 

        return None

    def _set_zone_notifier_master(self, zone_name_class, master_addr):
        self._zonemgr_refresh_info[zone_name_class]["notify_master"] = master_addr

    def _clear_zone_notifier_master(self, zone_name_class):
        if ("notify_master" in self._zonemgr_refresh_info[zone_name_class].keys()):
            del self._zonemgr_refresh_info[zone_name_class]["notify_master"]

    def _get_zone_state(self, zone_name_class):
        return self._zonemgr_refresh_info[zone_name_class]["zone_state"]

    def _set_zone_state(self, zone_name_class, zone_state):
        self._zonemgr_refresh_info[zone_name_class]["zone_state"] = zone_state 

    def _get_zone_refresh_timeout(self, zone_name_class):
        return self._zonemgr_refresh_info[zone_name_class]["refresh_timeout"]

    def _set_zone_refresh_timeout(self, zone_name_class, time):
        self._zonemgr_refresh_info[zone_name_class]["refresh_timeout"] = time

    def _get_zone_next_refresh_time(self, zone_name_class):
        return self._zonemgr_refresh_info[zone_name_class]["next_refresh_time"]

    def _set_zone_next_refresh_time(self, zone_name_class, time):
        self._zonemgr_refresh_info[zone_name_class]["next_refresh_time"] = time

    def _send_command(self, module_name, command_name, params):
        """Send command between modules."""
        msg = create_command(command_name, params)
        try:
            self._cc.group_sendmsg(msg, module_name)
        except socket.error:
            sys.stderr.write("[b10-zonemgr] Failed to send to module %s, the session has been closed." % module_name) 

    def _find_need_do_refresh_zone(self):
        """Find the first zone need do refresh, if no zone need
        do refresh, return the zone with minimum next_refresh_time.
        """
        zone_need_refresh = None
        for zone_name_class in self._zonemgr_refresh_info.keys():
            # Does the zone expired?
            if (ZONE_EXPIRED != self._get_zone_state(zone_name_class) and 
                self._zone_is_expired(zone_name_class)):
                log_msg("Zone (%s, %s) is expired." % zone_name_class)
                self._set_zone_state(zone_name_class, ZONE_EXPIRED)

            zone_state = self._get_zone_state(zone_name_class)
            # If zone is expired and doesn't receive notify, skip the zone
            if (ZONE_EXPIRED == zone_state and 
                (not self._get_zone_notifier_master(zone_name_class))):
                continue

            # If hasn't received refresh response but are within refresh timeout, skip the zone
            if (ZONE_REFRESHING == zone_state and
                (self._get_zone_refresh_timeout(zone_name_class) > self._get_current_time())):
                continue
                    
            # Get the zone with minimum next_refresh_time 
            if ((None == zone_need_refresh) or 
                (self._get_zone_next_refresh_time(zone_name_class) < 
                 self._get_zone_next_refresh_time(zone_need_refresh))):
                zone_need_refresh = zone_name_class

            # Find the zone need do refresh
            if (self._get_zone_next_refresh_time(zone_need_refresh) < self._get_current_time()):
                break

        return zone_need_refresh 

    
    def _do_refresh(self, zone_name_class):
        """Do zone refresh."""
        log_msg("Do refresh for zone (%s, %s)." % zone_name_class)
        self._set_zone_state(zone_name_class, ZONE_REFRESHING)
        self._set_zone_refresh_timeout(zone_name_class, self._get_current_time() + MAX_TRANSFER_TIMEOUT) 
        notify_master = self._get_zone_notifier_master(zone_name_class)
        # If the zone has notify master, send notify command to xfrin module
        if notify_master:
            param = {"zone_name" : zone_name_class[0],
                     "zone_class" : zone_name_class[1],
                     "master" : notify_master
                     }
            self._send_command(XFRIN_MODULE_NAME, ZONE_NOTIFY_COMMAND, param) 
            self._clear_zone_notifier_master(zone_name_class)
        # Send refresh command to xfrin module
        else:
            param = {"zone_name" : zone_name_class[0],
                     "zone_class" : zone_name_class[1]
                    }
            self._send_command(XFRIN_MODULE_NAME, ZONE_REFRESH_COMMAND, param)

    def _zone_mgr_is_empty(self):
        """Does zone manager has no zone?"""
        if not len(self._zonemgr_refresh_info):
            return True

        return False

    def _run_timer(self):
        while self._running:
            # Zonemgr has no zone.
            if self._zone_mgr_is_empty():
                timeout = LOWERBOUND_RETRY
            else:
                zone_need_refresh = self._find_need_do_refresh_zone()
                # If don't get zone with minimum next refresh time, set timer timeout = LOWERBOUND_REFRESH
                if not zone_need_refresh:
                    timeout = LOWERBOUND_RETRY
                else:
                    timeout = self._get_zone_next_refresh_time(zone_need_refresh) - self._get_current_time()
                    if (timeout < 0):
                        self._do_refresh(zone_need_refresh)
                        continue

            """ Wait for the socket notification for a maximum time of timeout 
            in seconds (as float)."""
            try:
                rlist, wlist, xlist = select.select([self._check_sock, self._read_sock], [], [], timeout)
            except select.error as e:
                if e.args[0] == errno.EINTR:
                    (rlist, wlist, xlist) = ([], [], [])
                else:
                    sys.stderr.write("[b10-zonemgr] Error with select(); %s\n" % e)
                    break

            for fd in rlist:
                if fd == self._read_sock: # awaken by shutdown socket 
                    # self._running will be False by now, if it is not a false
                    # alarm
                    continue
                if fd == self._check_sock: # awaken by check socket
                    self._check_sock.recv(32)

    def run_timer(self, daemon=False):
        """
        Keep track of zone timers. Spawns and starts a thread. The thread object is returned.

        You can stop it by calling shutdown().
        """
        # Small sanity check
        if self._running:
            raise RuntimeError("Trying to run the timers twice at the same time")

        # Prepare the launch
        self._running = True
        (self._read_sock, self._write_sock) = socket.socketpair()

        # Start the thread
        self._thread = threading.Thread(target = self._run_timer, args = ())
        if daemon:
            self._thread.setDaemon(True)
        self._thread.start()

        # Return the thread to anyone interested
        return self._thread

    def shutdown(self):
        """
        Stop the run_timer() thread. Block until it finished. This must be
        called from a different thread.
        """
        if not self._running:
            raise RuntimeError("Trying to shutdown, but not running")

        # Ask the thread to stop
        self._running = False
        self._write_sock.send(b'shutdown') # make self._read_sock readble
        # Wait for it to actually finnish
        self._thread.join()
        # Wipe out what we do not need
        self._thread = None
        self._read_sock = None
        self._write_sock = None

class Zonemgr:
    """Zone manager class."""
    def __init__(self):
        self._setup_session()
        self._db_file = self.get_db_file()
        # Create socket pair for communicating between main thread and zonemgr timer thread 
        self._master_socket, self._slave_socket = socket.socketpair(socket.AF_UNIX, socket.SOCK_STREAM)
        self._zone_refresh = ZonemgrRefresh(self._cc, self._db_file, self._slave_socket)
        self._zone_refresh.run_timer()

        self._lock = threading.Lock()
        self._shutdown_event = threading.Event()

    def _setup_session(self):
        """Setup two sessions for zonemgr, one(self._module_cc) is used for receiving 
        commands and config data sent from other modules, another one (self._cc)
        is used to send commands to proper modules."""
        self._cc = isc.cc.Session()
        self._module_cc = isc.config.ModuleCCSession(SPECFILE_LOCATION,
                                                  self.config_handler,
                                                  self.command_handler)
        self._module_cc.add_remote_config(AUTH_SPECFILE_LOCATION)
        self._config_data = self._module_cc.get_full_config()
        self._module_cc.start()

    def get_db_file(self):
        db_file, is_default = self._module_cc.get_remote_config_value(AUTH_MODULE_NAME, "database_file")
        # this too should be unnecessary, but currently the
        # 'from build' override isn't stored in the config
        # (and we don't have indirect python access to datasources yet)
        if is_default and "B10_FROM_BUILD" in os.environ:
            db_file = os.environ["B10_FROM_BUILD"] + "/bind10_zones.sqlite3"
        return db_file

    def shutdown(self):
        """Shutdown the zonemgr process. the thread which is keeping track of zone
        timers should be terminated.
        """ 
        self._zone_refresh.shutdown()

        self._slave_socket.close()
        self._master_socket.close()
        self._shutdown_event.set()

    def config_handler(self, new_config):
        """Update config data."""
        answer = create_answer(0)
        for key in new_config:
            if key not in self._config_data:
                answer = create_answer(1, "Unknown config data: " + str(key))
                continue
            self._config_data[key] = new_config[key]
        return answer

    def _parse_cmd_params(self, args, command):
        zone_name = args.get("zone_name")
        if not zone_name:
            raise ZonemgrException("zone name should be provided")

        zone_class = args.get("zone_class")
        if not zone_class:
            raise ZonemgrException("zone class should be provided")

        if (command != ZONE_NOTIFY_COMMAND):
            return (zone_name, zone_class)

        master_str = args.get("master")
        if not master_str:
            raise ZonemgrException("master address should be provided")

        return ((zone_name, zone_class), master_str)


    def command_handler(self, command, args):
        """Handle command receivd from command channel.
        ZONE_NOTIFY_COMMAND is issued by Auth process; ZONE_XFRIN_SUCCESS_COMMAND 
        and ZONE_XFRIN_FAILED_COMMAND are issued by Xfrin process; shutdown is issued
        by a user or Boss process. """
        answer = create_answer(0)
        if command == ZONE_NOTIFY_COMMAND:
            """ Handle Auth notify command"""
            # master is the source sender of the notify message.
            zone_name_class, master = self._parse_cmd_params(args, command)
            log_msg("Received notify command for zone (%s, %s)." % zone_name_class)
            with self._lock:
                self._zone_refresh.zone_handle_notify(zone_name_class, master)
            # Send notification to zonemgr timer thread
            self._master_socket.send(b" ")# make self._slave_socket readble

        elif command == ZONE_XFRIN_SUCCESS_COMMAND:
            """ Handle xfrin success command"""
            zone_name_class = self._parse_cmd_params(args, command)
            with self._lock:
                self._zone_refresh.zone_refresh_success(zone_name_class)
            self._master_socket.send(b" ")# make self._slave_socket readble

        elif command == ZONE_XFRIN_FAILED_COMMAND:
            """ Handle xfrin fail command"""
            zone_name_class = self._parse_cmd_params(args, command)
            with self._lock:
                self._zone_refresh.zone_refresh_fail(zone_name_class)
            self._master_socket.send(b" ")# make self._slave_socket readble

        elif command == "shutdown":
            self.shutdown()

        else:
            answer = create_answer(1, "Unknown command:" + str(command))

        return answer

    def run(self):
        while not self._shutdown_event.is_set():
            self._module_cc.check_command()

zonemgrd = None

def signal_handler(signal, frame):
    if zonemgrd:
        zonemgrd.shutdown()
        sys.exit(0)

def set_signal_handler():
    signal.signal(signal.SIGTERM, signal_handler)
    signal.signal(signal.SIGINT, signal_handler)

def set_cmd_options(parser):
    parser.add_option("-v", "--verbose", dest="verbose", action="store_true",
            help="display more about what is going on")

if '__main__' == __name__:
    try:
        parser = OptionParser()
        set_cmd_options(parser)
        (options, args) = parser.parse_args()
        VERBOSE_MODE = options.verbose

        set_signal_handler()
        zonemgrd = Zonemgr()
        zonemgrd.run()
    except KeyboardInterrupt:
        sys.stderr.write("[b10-zonemgr] exit zonemgr process\n")
    except isc.cc.session.SessionError as e:
        sys.stderr.write("[b10-zonemgr] Error creating zonemgr, " 
                           "is the command channel daemon running?\n")
    except isc.cc.session.SessionTimeout as e:
        sys.stderr.write("[b10-zonemgr] Error creating zonemgr, " 
                           "is the configuration manager running?\n")
    except isc.config.ModuleCCSessionError as e:
        sys.stderr.write("[b10-zonemgr] exit zonemgr process: %s\n" % str(e))

    if zonemgrd:
        zonemgrd.shutdown()