# -*- coding: utf-8 -*-
from setuphelpers import *
import re
import datetime
import jinja2

###################
#
# This package is inspireted by "(Open)SSH secure use recommendations" documentation
# from National Cybersecurity Agency of France / ANSSI.
# English link : https://www.ssi.gouv.fr/en/guide/openssh-secure-use-recommendations/
# Franch link : https://www.ssi.gouv.fr/guide/recommandations-pour-un-usage-securise-dopenssh/
#
###################

# If you want to recording all command, set True
trap_command = False

options_list_check = ['Protocol 2','Port 22','#HostKey /etc/ssh/ssh_host_rsa_key','#HostKey /etc/ssh/ssh_host_ecdsa_key','HostKey /etc/ssh/ssh_host_ed25519_key',
'LoginGraceTime 2m','PermitRootLogin no','StrictModes yes','PasswordAuthentication no','PermitEmptyPasswords no','ChallengeResponseAuthentication no',
'UsePAM yes','AllowTcpForwarding no','X11Forwarding no','TCPKeepAlive yes','ClientAliveInterval 600','ClientAliveCountMax 0','PermitUserEnvironment no',
'AllowAgentForwarding no']

# If some servers need other AllowUsers than define in get_allow_users().
add_allow_users = {'server':{'user':'user@server','comment':'servername'}
                }

sshd_config_file = makepath('/etc','ssh','sshd_config')


def get_allow_users():
    add_user = ''
    add_comment = ''
    for server in add_allow_users:
        if get_computername().lower() == server:
            add_user = add_allow_users[server]['user']
            add_comment = add_allow_users[server]['comment']

    default_allow_users = f"""AllowUsers admin {add_user}
#                       {add_comment}
"""
    return default_allow_users


def install():
    print("Installing: %s" % control.package)

    error('This package is protect against accidental launch. To disable the protection, edit the package and remove this line')

    options_add = []
    options_in = []

    for option in options_list_check:
        pattern = re.compile("^(%s)$" % option)

        for line in open(sshd_config_file):
            for match in re.finditer(pattern, line):
                options_in.append(line.replace('\n',''))

    pattern_allow_users = re.compile("^%s$" % get_allow_users().split('\n')[0])
    for line in open(sshd_config_file):
        for match in re.finditer(pattern_allow_users,line):
            options_in.append(line.split('\n')[0])

    options_list_check.append(get_allow_users().split('\n')[0])

    print('Parameters already set : %s' % options_in)

    for option in options_list_check:
        if option in options_in:
            pass
        else:
            options_add.append(option)

    print('This parameters are to set : %s' % options_add)

    if len(options_add)>0:
        print('Backup old file config')
        backup_file = makepath('/etc','ssh','sshd_config.old')
        if isfile(backup_file):
            backup_file =  makepath('/etc','ssh','sshd_config.old%s' % datetime.datetime.now().strftime("%Y%m%d_%H%M%S"))
        filecopyto(sshd_config_file,backup_file)

        jinja_env = jinja2.Environment(loader=jinja2.FileSystemLoader('templates'))
        template = jinja_env.get_template('sshd_config.j2')

        template_variables = {
            'allow_users': get_allow_users(),
        }
        config_string = template.render(template_variables)

        print(f'Create sshd_config configuration file with allow_users {get_allow_users()}')
        with open(makepath('/etc','ssh','sshd_config'), 'wt') as dst_file:
            dst_file.write(config_string)

        print('Set 600 permission on sshd_config file')
        run('chmod 600 /etc/ssh/sshd_config')

        print('Set root ownership on sshd_config file')
        run('chown root:root /etc/ssh/sshd_config')

        print('Restart sshd')
        run('systemctl restart sshd')

        print('Set permissions on /etc/ssh/sshd_config')

        run('chown root:root /etc/ssh/sshd_config')
        run('chmod og-rwx /etc/ssh/sshd_config')


    if trap_command:

        print('Set trap login')

        trap_syslog = """function trap_to_syslog {
    printf "%s %s from %s %s" "$HOSTNAME" "$SSHCLIENTUSER" "$SSH_CLIENT" "$USER[$$]@$PWD> $BASH_COMMAND" |logger -p local3.notice
    }
    trap trap_to_syslog DEBUG

        """

        print('Check')
        enable_trap = False
        if is_debian_based():
            bashrc_path = makepath('/etc','bash.bashrc')
        else:
            bashrc_path = makepath('/etc','bashrc')

        for line in open(bashrc_path):
            for match in re.finditer('^(function trap_to_syslog {)$',line):
                enable_trap = True

        if not enable_trap:
            print('Set trap syslog')
            with open(bashrc_path, 'a') as bashrc:
                bashrc.write(trap_syslog)


def audit():

    options_add = []
    options_in = []
    for option in options_list_check:
        pattern = re.compile("^(%s)$" % option)
        for line in open(sshd_config_file):
            for match in re.finditer(pattern, line):
                options_in.append(line.replace('\n',''))

    pattern_allow_users = re.compile("^%s$" % get_allow_users().split('\n')[0])
    for line in open(sshd_config_file):
        for match in re.finditer(pattern_allow_users,line):
            options_in.append(line.split('\n')[0])

    options_list_check.append(get_allow_users().split('\n')[0])

    for option in options_list_check:
        if option in options_in:
            pass
        else:
            options_add.append(option)

    if len(options_add) > 0:
        print('Some parameters are wrongs ! %s' % options_add)
        WAPT.write_audit_data_if_changed("Securized SSH", 'Parameters in fault', options_add, keep_days=365)
        return "ERROR"
    else:
        print('All parameters are OK')
        WAPT.write_audit_data_if_changed("Securized SSH", 'Parameters in fault', "OK", keep_days=365)
        return "OK"