config/config.py

#! /usr/bin/python

#  Copyright 2014 Linaro Limited
#  Author: Steve McIntyre <steve.mcintyre@linaro.org>
#
#  This program 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 2 of the License, or
#  (at your option) any later version.
#
#  This program 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 this program; if not, write to the Free Software
#  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
#  MA 02110-1301, USA.
#
#  VLANd simple config parser
#

import ConfigParser
import os, sys, re

if __name__ == '__main__':
    vlandpath = os.path.abspath(os.path.normpath(os.path.dirname(sys.argv[0])))
    sys.path.insert(0, vlandpath)
    sys.path.insert(0, "%s/.." % vlandpath)

from errors import ConfigError

def is_positive(text):
    if text in ('1', 'y', 'Y', 't', 'T', 'True', 'true'):
        return True
    elif text in ('0', 'n', 'N', 'f', 'F', 'False', 'false'):
        return False

class DaemonConfigClass:
    """ Simple container for stuff to make for nicer syntax """

    def __repr__(self):
        return "<DaemonConfig: port: %s>" % (self.port)

class DBConfigClass:
    """ Simple container for stuff to make for nicer syntax """

    def __repr__(self):
        return "<DBConfig: server: %s, port: %s, dbname: %s, username: %s, password: %s>" % (self.server, self.port, self.dbname, self.username, self.password)

class LoggingConfigClass:
    """ Simple container for stuff to make for nicer syntax """

    def __repr__(self):
        return "<LoggingConfig: level: %s, filename: %s>" % (self.level, self.filename)

class SwitchConfigClass:
    """ Simple container for stuff to make for nicer syntax """
    def __repr__(self):
        return "<SwitchConfig: name: %s, section: %s, driver: %s, username: %s, password: %s, enable_password: %s>" % (self.name, self.section, self.driver, self.username, self.password, self.enable_password)

class VlanConfig:
    """VLANd config class"""
    def __init__(self, filenames):

        config = ConfigParser.RawConfigParser({
            # Set default values
            'server': None,
            'port': None,
            'dbname': None,
            'username': None,
            'password': None,
            'name': None,
            'driver': None,
            'enable_password': None,
            'debug': False,
            })

        config.read(filenames)

        # Parse out the config file
        # Must have a [database] section
        # May have a [vland] section
        # May have a [logging] section
        # May have multiple [switch 'foo'] sections
        if not config.has_section('database'):
            raise ConfigError('No database configuration section found')

        # No DB-specific defaults to set
        self.database = DBConfigClass()

        # Set defaults logging details
        self.logging = LoggingConfigClass()
        self.logging.level = None
        self.logging.filename = None

        # Set default port number and VLAN tag
        self.vland = DaemonConfigClass()
        self.vland.port = 3080
        self.vland.default_vlan_tag = 1

        # No switch-specific defaults to set
        self.switches = {}

        sw_regex = re.compile('(switch)\ (.*)', flags=re.I)
        for section in config.sections():
            if section == 'database':
                try:
                    self.database.server = config.get(section, 'server')
                except ConfigParser.NoOptionError:
                    pass
                except:
                    raise ConfigError('Invalid database configuration (server)')

                try:
                    port = config.get(section, 'port')
                    if port is not None:
                        self.database.port = config.getint(section, 'port')
                except ConfigParser.NoOptionError:
                    pass
                except:
                    raise ConfigError('Invalid database configuration (port)')

                try:
                    self.database.dbname = config.get(section, 'dbname')
                except ConfigParser.NoOptionError:
                    pass
                except:
                    raise ConfigError('Invalid database configuration (dbname)')

                try:
                    self.database.username = config.get(section, 'username')
                except ConfigParser.NoOptionError:
                    pass
                except:
                    raise ConfigError('Invalid database configuration (username)')

                try:
                    self.database.password = config.get(section, 'password')
                except ConfigParser.NoOptionError:
                    pass
                except:
                    raise ConfigError('Invalid database configuration (password)')

                # Other database config options are optional, but these are not
                if self.database.dbname is None or self.database.username is None:
                    raise ConfigError('Database configuration section incomplete')

            elif section == 'logging':
                try:
                    self.logging.level = config.get(section, 'level')
                except ConfigParser.NoOptionError:
                    pass
                except:
                    raise ConfigError('Invalid logging configuration (level)')

                try:
                    self.logging.filename = config.get(section, 'filename')
                except ConfigParser.NoOptionError:
                    pass
                except:
                    raise ConfigError('Invalid logging configuration (filename)')

            elif section == 'vland':
                try:
                    self.vland.port = config.getint(section, 'port')
                except ConfigParser.NoOptionError:
                    pass
                except:
                    raise ConfigError('Invalid vland configuration (port)')

                try:
                    self.vland.default_vlan_tag = config.getint(section, 'default_vlan_tag')
                except ConfigParser.NoOptionError:
                    pass
                except:
                    raise ConfigError('Invalid vland configuration (default_vlan_tag)')

            else:
                match = sw_regex.match(section)
                if match:
                    # Constraint: switch names must be unique! See if
                    # there's already a switch with this name
                    name = config.get(section, 'name')
                    for key in self.switches.keys():
                        if name == key:
                            raise ConfigError('Found switches with the same name (%s)' % name)
                    self.switches[name] = SwitchConfigClass()
                    self.switches[name].name = name
                    self.switches[name].section = section
                    self.switches[name].driver = config.get(section, 'driver')
                    self.switches[name].username = config.get(section, 'username')
                    self.switches[name].password = config.get(section, 'password')
                    self.switches[name].enable_password = config.get(section, 'enable_password')
                    self.switches[name].debug = config.get(section, 'debug')
                    if not is_positive(self.switches[name].debug):
                        self.switches[name].debug = False
                    elif is_positive(self.switches[name].debug):
                        self.switches[name].debug = True
                    else:
                        raise ConfigError('Invalid vland configuration (switch "%s", debug "%s"' % (name, self.switches[name].debug))
                else:
                    raise ConfigError('Unrecognised config section %s' % section)

    def __del__(self):
        pass

if __name__ == '__main__':
    c = VlanConfig(filenames=('./vland.cfg',))
    print c.database
    print c.vland
    for switch in c.switches:
        print c.switches[switch]