#!/usr/bin/env python3

# coding: utf-8

# Copyright 2012 - 2014, Pascal Volk

# See COPYING for distribution information.

"""

    Use this script in order to set database permissions for your Dovecot

    and Postfix database users.

    Run `python set-permissions.py -h` for details.

"""

import getpass

import sys

from argparse import ArgumentDefaultsHelpFormatter, ArgumentParser

import psycopg2

def check_args(args, err_hdlr):

    if not args.postfix:

        err_hdlr('missing Postfix database user name')

    if not args.dovecot:

        err_hdlr('missing Dovecot database user name')

    if args.askp:

        args.dbpass = getpass.getpass()

def get_dbh(database, user, password, host, port):

    return psycopg2.connect(database=database, user=user,

                            password=password, host=host, port=port)

def get_argparser():

    descr = 'Set permissions for Dovecot and Postfix in the vmm database.'

    parser = ArgumentParser(description=descr, usage='%(prog)s OPTIONS',

                            formatter_class=ArgumentDefaultsHelpFormatter)

    parser.add_argument('-a', '--askpass', dest='askp',

            action='store_true', help='Prompt for the database password.')

    parser.add_argument('-H', '--host', dest='host', metavar='HOST',

            help='Hostname or IP address of the database server. Leave ' +

                 'blank in order to use the default Unix-domain socket.')

    parser.add_argument('-n', '--name', dest='name', metavar='NAME',

            default='mailsys',

            help='Specifies the name of the database to connect to.')

    parser.add_argument('-p', '--pass', dest="dbpass", metavar='PASS',

            help='Password for the database connection.')

    parser.add_argument('-P', '--port', dest='port', metavar='PORT',

            type=int, default=5432,

            help='Specifies the TCP port or the local Unix-domain socket ' +

                 'file extension on which the server is listening for ' +

                 'connections.')

    parser.add_argument('-U', '--user', dest='user', metavar='USER',

            default=getpass.getuser(),

            help='Connect to the database as the user USER instead of the ')

    parser.add_argument('-D', '--dovecot', dest='dovecot', metavar='USER',

            default='dovecot',

            help='Database user name of the Dovecot database user.')

    parser.add_argument('-M', '--postfix', dest='postfix', metavar='USER',

            default='postfix',

            help='Database user name of the Postfix (MTA)  database user.')

    return parser

def set_permissions(dbh, dc_vers, dovecot, postfix):

    dc_rw = ('userquota_11', 'userquota')[dc_vers == 12]

    dbc = dbh.cursor()

    dbc.execute('GRANT SELECT ON domain_data, domain_name, mailboxformat, '

                'maillocation, quotalimit, service_set, users TO %s' % dovecot)

    dbc.execute('GRANT SELECT, INSERT, UPDATE, DELETE ON %s TO %s' %

                (dc_rw, dovecot))

    dbc.execute('GRANT SELECT ON alias, catchall, domain_data, domain_name, '

                'maillocation, postfix_gid, relocated, transport, users TO %s'

                % postfix)

    dbc.close()

def set_permissions84(dbh, dc_vers, dovecot, postfix):

    dc_rw_tbls = ('userquota_11', 'userquota')[dc_vers == 12]

    dc_ro_tbls = 'mailboxformat, maillocation, service_set, quotalimit'

    pf_ro_tbls = 'alias, catchall, postfix_gid, relocated, transport'

    db = dict(dovecot=dovecot, postfix=postfix)

    db['dovecot_tbls'] = {

        'domain_data': 'domaindir, gid, qid, ssid',

        'domain_name': 'domainname, gid',

        'users': 'gid, local_part, mid, passwd, qid, ssid, uid',

    }

    db['postfix_tbls'] = {

        'domain_data': 'domaindir, gid, tid',

        'domain_name': 'domainname, gid',

        'maillocation': 'directory, mid',

        'users': 'gid, local_part, mid, tid, uid',

    }

    dbc = dbh.cursor()

    dbc.execute('GRANT SELECT, INSERT, UPDATE, DELETE ON %s TO %s' %

                (dc_rw_tbls, db['dovecot']))

    dbc.execute('GRANT SELECT ON %s TO %s' % (dc_ro_tbls, db['dovecot']))

    dbc.execute('GRANT SELECT ON %s TO %s' % (pf_ro_tbls, db['postfix']))

    for table, columns in db['dovecot_tbls'].items():

        dbc.execute('GRANT SELECT (%s) ON %s TO %s' % (columns, table,

                                                       db['dovecot']))

    for table, columns in db['postfix_tbls'].items():

        dbc.execute('GRANT SELECT (%s) ON %s TO %s' % (columns, table,

                                                       db['postfix']))

    dbc.close()

def set_versions(dbh, versions):

    dbc = dbh.cursor()

    if hasattr(dbh, 'server_version'):

        versions['pgsql'] = dbh.server_version

    else:

        try:

            dbc.execute("SELECT current_setting('server_version_num')")

            versions['pgsql'] = int(dbc.fetchone()[0])

        except psycopg2.DatabaseError:

            versions['pgsql'] = 80199

    dbc.execute("SELECT relname FROM pg_stat_user_tables WHERE relname LIKE "

                "'userquota%'")

    res = dbc.fetchall()

    dbc.close()

    tbls = [tbl[0] for tbl in res]

    if 'userquota' in tbls:

        versions['dovecot'] = 12

    elif 'userquota_11' in tbls:

        versions['dovecot'] = 11

    else:

        sys.stderr.write('error: no userquota table found\nis "' + dbh.dsn +

                         '" correct? is the database up to date?\n')

        dbh.close()

        raise SystemExit(1)

if __name__ == '__main__':

    argparser = get_argparser()

    args = argparser.parse_args()

    check_args(args, argparser.error)

    dbh = get_dbh(args.name, args.user, args.dbpass, args.host, args.port)

    versions = {}

    set_versions(dbh, versions)

    if versions['pgsql'] < 80400:

        set_permissions(dbh, versions['dovecot'], args.dovecot, args.postfix)

    else:

        set_permissions84(dbh, versions['dovecot'], args.dovecot, args.postfix)

    dbh.commit()

    dbh.close()