#!/usr/bin/env python3
#
# Copyright (C) 2018-2020 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# 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, see <http://www.gnu.org/licenses/>.

import sys
import os
import re
import subprocess
import jinja2
import socket
import time
import syslog as sl

from vyos.config import Config
from vyos import ConfigError

pidfile = r'/var/run/accel_sstp.pid'
sstp_cnf_dir = r'/etc/accel-ppp/sstp'
chap_secrets = sstp_cnf_dir + '/chap-secrets'
sstp_conf = sstp_cnf_dir + '/sstp.config'
ssl_cert_dir = r'/config/user-data/sstp'

# config path creation
if not os.path.exists(sstp_cnf_dir):
    os.makedirs(sstp_cnf_dir)
    sl.syslog(sl.LOG_NOTICE, sstp_cnf_dir + " created")

if not os.path.exists(ssl_cert_dir):
    os.makedirs(ssl_cert_dir)
    sl.syslog(sl.LOG_NOTICE, ssl_cert_dir + " created")

sstp_config = '''
### generated by vpn_sstp.py ###
[modules]
log_syslog
sstp
ippool
shaper
{% if authentication['mode'] == 'local' %}
chap-secrets
{% endif -%}
{% for proto in authentication['auth_proto'] %}
{{proto}}
{% endfor %}
{% if authentication['mode'] == 'radius' %}
radius
{% endif %}

[core]
thread-count={{thread_cnt}}

[common]
single-session=replace

[log]
syslog=accel-sstp,daemon
copy=1
level=5

[client-ip-range]
disable

[sstp]
verbose=1
accept=ssl
{% if certs %}
ssl-ca-file=/config/user-data/sstp/{{certs['ca']}}
ssl-pemfile=/config/user-data/sstp/{{certs['server-cert']}}
ssl-keyfile=/config/user-data/sstp/{{certs['server-key']}}
{% endif %}

{%if ip_pool %}
[ip-pool]
gw-ip-address={{gw}}
{% for sn in ip_pool %}
{{sn}}
{% endfor %}
{% endif %}

{% if dnsv4 %}
[dns]
{% for dns in dnsv4 -%}
dns{{ loop.index }}={{ dns }}
{% endfor -%}
{% endif %}

{% if authentication['mode'] == 'local' %}
[chap-secrets]
chap-secrets=/etc/accel-ppp/sstp/chap-secrets
{% endif %}

{%- if authentication['mode'] == 'radius' %}
[radius]
verbose=1
{% for rsrv in authentication['radius-srv']: %}
server={{rsrv}},{{authentication['radius-srv'][rsrv]['secret']}},\
req-limit={{authentication['radius-srv'][rsrv]['req-limit']}},\
fail-time={{authentication['radius-srv'][rsrv]['fail-time']}}
{% endfor -%}
{% if authentication['radiusopt']['acct-timeout'] %}
acct-timeout={{authentication['radiusopt']['acct-timeout']}}
{% endif -%}
{% if authentication['radiusopt']['timeout'] %}
timeout={{authentication['radiusopt']['timeout']}}
{% endif -%}
{% if authentication['radiusopt']['max-try'] %}
max-try={{authentication['radiusopt']['max-try']}}
{% endif -%}
{% if authentication['radiusopt']['nas-id'] %}
nas-identifier={{authentication['radiusopt']['nas-id']}}
{% endif -%}
{% if authentication['radiusopt']['nas-ip'] %}
nas-ip-address={{authentication['radiusopt']['nas-ip']}}
{% endif -%}
{% if authentication['radiusopt']['dae-srv'] %}
dae-server={{authentication['radiusopt']['dae-srv']['ip-addr']}}:\
{{authentication['radiusopt']['dae-srv']['port']}},\
{{authentication['radiusopt']['dae-srv']['secret']}}
{% endif -%}
{% endif %}

[ppp]
verbose=1
check-ip=1
{% if mtu %}
mtu={{mtu}}
{% endif -%}
{% if ppp['mppe'] %}
mppe={{ppp['mppe']}}
{% endif -%}
{% if ppp['lcp-echo-interval'] %}
lcp-echo-interval={{ppp['lcp-echo-interval']}}
{% endif -%}
{% if ppp['lcp-echo-failure'] %}
lcp-echo-failure={{ppp['lcp-echo-failure']}}
{% endif -%}
{% if ppp['lcp-echo-timeout'] %}
lcp-echo-timeout={{ppp['lcp-echo-timeout']}}
{% endif %}

{% if authentication['radiusopt']['shaper'] %}
[shaper]
verbose=1
attr={{authentication['radiusopt']['shaper']['attr']}}
{% if authentication['radiusopt']['shaper']['vendor'] %}
vendor={{authentication['radiusopt']['shaper']['vendor']}}
{% endif -%}
{% endif %}

[cli]
tcp=127.0.0.1:2005
'''

# sstp chap secrets
chap_secrets_conf = '''
# username  server  password  acceptable local IP addresses   shaper
{% for user in authentication['local-users'] %}
{% if authentication['local-users'][user]['state'] == 'enabled' %}
{% if (authentication['local-users'][user]['upload']) and (authentication['local-users'][user]['download']) %}
{{user}}\t*\t{{authentication['local-users'][user]['passwd']}}\t{{authentication['local-users'][user]['ip']}}\t\
{{authentication['local-users'][user]['download']}}/{{authentication['local-users'][user]['upload']}}
{% else %}
{{user}}\t*\t{{authentication['local-users'][user]['passwd']}}\t{{authentication['local-users'][user]['ip']}}
{% endif %}
{% endif %}
{% endfor %}
'''
###
# inline helper functions
###
# depending on hw and threads, daemon needs a little to start
# if it takes longer than 100 * 0.5 secs, exception is being raised
# not sure if that's the best way to check it, but it worked so far quite well
###


def chk_con():
    cnt = 0
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    while True:
        try:
            s.connect(("127.0.0.1", 2005))
            s.close()
            break
        except ConnectionRefusedError:
            time.sleep(0.5)
            cnt += 1
            if cnt == 100:
                raise("failed to start sstp server")
                break

# chap_secrets file if auth mode local


def write_chap_secrets(c):
    tmpl = jinja2.Template(chap_secrets_conf, trim_blocks=True)
    chap_secrets_txt = tmpl.render(c)
    old_umask = os.umask(0o077)
    open(chap_secrets, 'w').write(chap_secrets_txt)
    os.umask(old_umask)
    sl.syslog(sl.LOG_NOTICE, chap_secrets + ' written')


def accel_cmd(cmd=''):
    if not cmd:
        return None
    try:
        ret = subprocess.check_output(
            ['/usr/bin/accel-cmd', '-p', '2005', cmd]).decode().strip()
        return ret
    except:
        return 1

# check ig local-ip is in client pool subnet


###
# inline helper functions end
###

def get_config():
    base_path = ['vpn', 'sstp']
    c = Config()
    if not c.exists(base_path):
        return None

    c.set_level(base_path)

    config_data = {
        'authentication': {
            'local-users': {
            },
            'mode': 'local',
            'auth_proto': [],
            'radius-srv': {},
            'radiusopt': {},
            'dae-srv': {}
        },
        'certs': {
            'ca': None,
            'server-key': None,
            'server-cert': None
        },
        'ip_pool': [],
        'gw': None,
        'dnsv4': [],
        'mtu': None,
        'ppp': {},
    }

    # local auth
    if c.exists('authentication mode local'):
        if c.exists('authentication local-users'):
            for usr in c.list_nodes('authentication local-users username'):
                config_data['authentication']['local-users'].update(
                    {
                        usr: {
                            'passwd': None,
                            'state': 'enabled',
                            'ip': '*',
                            'upload': None,
                            'download': None
                        }
                    }
                )
                if c.exists('authentication local-users username ' + usr + ' password'):
                    config_data['authentication']['local-users'][usr]['passwd'] = c.return_value(
                        'authentication local-users username ' + usr + ' password')
                if c.exists('authentication local-users username ' + usr + ' disable'):
                    config_data['authentication']['local-users'][usr]['state'] = 'disable'
                if c.exists('authentication local-users username ' + usr + ' static-ip'):
                    config_data['authentication']['local-users'][usr]['ip'] = c.return_value(
                        'authentication local-users username ' + usr + ' static-ip')
                if c.exists('authentication local-users username ' + usr + ' rate-limit download'):
                    config_data['authentication']['local-users'][usr]['download'] = c.return_value(
                        'authentication local-users username ' + usr + ' rate-limit download')
                if c.exists('authentication local-users username ' + usr + ' rate-limit upload'):
                    config_data['authentication']['local-users'][usr]['upload'] = c.return_value(
                        'authentication local-users username ' + usr + ' rate-limit upload')

    if c.exists('authentication protocols'):
        auth_mods = {'pap': 'pap', 'chap': 'auth_chap_md5',
                     'mschap': 'auth_mschap_v1', 'mschap-v2': 'auth_mschap_v2'}
        for proto in c.return_values('authentication protocols'):
            config_data['authentication']['auth_proto'].append(
                auth_mods[proto])
    else:
        config_data['authentication']['auth_proto'] = ['auth_mschap_v2']

    # RADIUS auth and settings
    if c.exists('authentication mode radius'):
        config_data['authentication']['mode'] = c.return_value(
            'authentication mode')
        if c.exists('authentication radius-server'):
            for rsrv in c.list_nodes('authentication radius-server'):
                config_data['authentication']['radius-srv'][rsrv] = {}
                if c.exists('authentication radius-server ' + rsrv + ' secret'):
                    config_data['authentication']['radius-srv'][rsrv]['secret'] = c.return_value(
                        'authentication radius-server ' + rsrv + ' secret')
                else:
                    config_data['authentication']['radius-srv'][rsrv]['secret'] = None
                if c.exists('authentication radius-server ' + rsrv + ' fail-time'):
                    config_data['authentication']['radius-srv'][rsrv]['fail-time'] = c.return_value(
                        'authentication radius-server ' + rsrv + ' fail-time')
                else:
                    config_data['authentication']['radius-srv'][rsrv]['fail-time'] = 0
                if c.exists('authentication radius-server ' + rsrv + ' req-limit'):
                    config_data['authentication']['radius-srv'][rsrv]['req-limit'] = c.return_value(
                        'authentication radius-server ' + rsrv + ' req-limit')
                else:
                    config_data['authentication']['radius-srv'][rsrv]['req-limit'] = 0

        # advanced radius-setting
        if c.exists('authentication radius-settings'):
            if c.exists('authentication radius-settings acct-timeout'):
                config_data['authentication']['radiusopt']['acct-timeout'] = c.return_value(
                    'authentication radius-settings acct-timeout')
            if c.exists('authentication radius-settings max-try'):
                config_data['authentication']['radiusopt']['max-try'] = c.return_value(
                    'authentication radius-settings max-try')
            if c.exists('authentication radius-settings timeout'):
                config_data['authentication']['radiusopt']['timeout'] = c.return_value(
                    'authentication radius-settings timeout')
            if c.exists('authentication radius-settings nas-identifier'):
                config_data['authentication']['radiusopt']['nas-id'] = c.return_value(
                    'authentication radius-settings nas-identifier')
            if c.exists('authentication radius-settings nas-ip-address'):
                config_data['authentication']['radiusopt']['nas-ip'] = c.return_value(
                    'authentication radius-settings nas-ip-address')
            if c.exists('authentication radius-settings dae-server'):
                config_data['authentication']['radiusopt'].update(
                    {
                        'dae-srv': {
                            'ip-addr': c.return_value('authentication radius-settings dae-server ip-address'),
                            'port': c.return_value('authentication radius-settings dae-server port'),
                            'secret': str(c.return_value('authentication radius-settings dae-server secret'))
                        }
                    }
                )
            if c.exists('authentication radius-settings rate-limit enable'):
                if not c.exists('authentication radius-settings rate-limit attribute'):
                    config_data['authentication']['radiusopt']['shaper'] = {
                        'attr': 'Filter-Id'}
                else:
                    config_data['authentication']['radiusopt']['shaper'] = {
                        'attr': c.return_value('authentication radius-settings rate-limit attribute')
                    }
                if c.exists('authentication radius-settings rate-limit vendor'):
                    config_data['authentication']['radiusopt']['shaper']['vendor'] = c.return_value(
                        'authentication radius-settings rate-limit vendor')

    if c.exists('sstp-settings ssl-certs ca'):
        config_data['certs']['ca'] = c.return_value(
            'sstp-settings ssl-certs ca')
    if c.exists('sstp-settings ssl-certs server-cert'):
        config_data['certs']['server-cert'] = c.return_value(
            'sstp-settings ssl-certs server-cert')
    if c.exists('sstp-settings ssl-certs server-key'):
        config_data['certs']['server-key'] = c.return_value(
            'sstp-settings ssl-certs server-key')

    if c.exists('network-settings client-ip-settings subnet'):
        config_data['ip_pool'] = c.return_values(
            'network-settings client-ip-settings subnet')
    if c.exists('network-settings client-ip-settings gateway-address'):
        config_data['gw'] = c.return_value(
            'network-settings client-ip-settings gateway-address')
    if c.exists('network-settings name-server'):
        config_data['dnsv4'] = c.return_values('network-settings name-server')
    if c.exists('network-settings mtu'):
        config_data['mtu'] = c.return_value('network-settings mtu')

    # ppp
    if c.exists('ppp-settings mppe'):
        config_data['ppp']['mppe'] = c.return_value('ppp-settings mppe')
    if c.exists('ppp-settings lcp-echo-failure'):
        config_data['ppp']['lcp-echo-failure'] = c.return_value(
            'ppp-settings lcp-echo-failure')
    if c.exists('ppp-settings lcp-echo-interval'):
        config_data['ppp']['lcp-echo-interval'] = c.return_value(
            'ppp-settings lcp-echo-interval')
    if c.exists('ppp-settings lcp-echo-timeout'):
        config_data['ppp']['lcp-echo-timeout'] = c.return_value(
            'ppp-settings lcp-echo-timeout')

    return config_data


def verify(c):
    if c == None:
        return None

    # vertify auth settings
    if c['authentication']['mode'] == 'local':
        if not c['authentication']['local-users']:
            raise ConfigError(
                'sstp-server authentication local-users required')

        for usr in c['authentication']['local-users']:
            if not c['authentication']['local-users'][usr]['passwd']:
                raise ConfigError('user ' + usr + ' requires a password')
            # if up/download is set, check that both have a value
            if c['authentication']['local-users'][usr]['upload']:
                if not c['authentication']['local-users'][usr]['download']:
                    raise ConfigError(
                        'user ' + usr + ' requires download speed value')
            if c['authentication']['local-users'][usr]['download']:
                if not c['authentication']['local-users'][usr]['upload']:
                    raise ConfigError(
                        'user ' + usr + ' requires upload speed value')

    if len(c['dnsv4']) > 2:
        raise ConfigError("Only 2 DNS name-servers can be configured")

    if not c['certs']['ca'] or not c['certs']['server-key'] or not c['certs']['server-cert']:
        raise ConfigError(
            'service sstp-server sstp-settings ssl-certs needs the ssl certificates set up')
    else:
        ssl_path = ssl_cert_dir + '/'
        if not os.path.exists(ssl_path + c['certs']['ca']):
            raise ConfigError('CA {0} doesn\'t exist'.format(
                ssl_path + c['certs']['ca']))
        if not os.path.exists(ssl_path + c['certs']['server-cert']):
            raise ConfigError('SSL Cert {0} doesn\'t exist'.format(
                ssl_path + c['certs']['server-cert']))
        if not os.path.exists(ssl_path + c['certs']['server-cert']):
            raise ConfigError('SSL Key {0} doesn\'t exist'.format(
                ssl_path + c['certs']['server-key']))

    if c['authentication']['mode'] == 'radius':
        if len(c['authentication']['radius-srv']) == 0:
            raise ConfigError(
                'service sstp-server authentication radius-server needs a value')
        for rsrv in c['authentication']['radius-srv']:
            if c['authentication']['radius-srv'][rsrv]['secret'] == None:
                raise ConfigError(
                    'service sstp-server authentication radius-server {0} secret requires a value'.format(rsrv))

    if c['authentication']['mode'] == 'local':
        if not c['ip_pool']:
            print (
                "WARNING: service sstp-server network-settings client-ip-settings subnet requires a value")
        if not c['gw']:
            print (
                "WARNING: service sstp-server network-settings client-ip-settings gateway-address requires a value")


def generate(c):
    if c == None:
        return None

    # accel-cmd reload doesn't work so any change results in a restart of the daemon
    try:
        if os.cpu_count() == 1:
            c['thread_cnt'] = 1
        else:
            c['thread_cnt'] = int(os.cpu_count()/2)
    except KeyError:
        if os.cpu_count() == 1:
            c['thread_cnt'] = 1
        else:
            c['thread_cnt'] = int(os.cpu_count()/2)

    tmpl = jinja2.Template(sstp_config, trim_blocks=True)
    config_text = tmpl.render(c)
    open(sstp_conf, 'w').write(config_text)

    if c['authentication']['local-users']:
        write_chap_secrets(c)

    return c


def apply(c):
    if c == None:
        if os.path.exists(pidfile):
            accel_cmd('shutdown hard')
            if os.path.exists(pidfile):
                os.remove(pidfile)
        return None

    if not os.path.exists(pidfile):
        ret = subprocess.call(
            ['/usr/sbin/accel-pppd', '-c', sstp_conf, '-p', pidfile, '-d'])
        chk_con()
        if ret != 0 and os.path.exists(pidfile):
            os.remove(pidfile)
            raise ConfigError('accel-pppd failed to start')
    else:
        accel_cmd('restart')
        sl.syslog(sl.LOG_NOTICE, "reloading config via daemon restart")


if __name__ == '__main__':
    try:
        c = get_config()
        verify(c)
        generate(c)
        apply(c)
    except ConfigError as e:
        print(e)
        sys.exit(1)