#!/usr/bin/env python3
#
# Copyright (C) 2018 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_pppoe.pid'
pppoe_cnf_dir = r'/etc/accel-ppp/pppoe'
chap_secrets = pppoe_cnf_dir + '/chap-secrets'
pppoe_conf = pppoe_cnf_dir + '/pppoe.config'
# accel-pppd -d -c /etc/accel-ppp/pppoe/pppoe.config -p
# /var/run/accel_pppoe.pid

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

pppoe_config = '''
### generated by accel_pppoe.py ###
[modules]
log_syslog
pppoe
{% if authentication['mode'] == 'radius' %}
radius
{% endif %}
ippool
{% if client_ipv6_pool %}
ipv6pool
ipv6_nd
ipv6_dhcp
{% endif %}
chap-secrets
auth_pap
auth_chap_md5
auth_mschap_v1
auth_mschap_v2
#pppd_compat
shaper
{% if snmp == 'enable' or snmp == 'enable-ma' %}
net-snmp
{% endif %}
{% if limits %}
connlimit
{% endif %}

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

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

{% if snmp == 'enable-ma' %}
[snmp]
master=1
{% endif -%}

[client-ip-range]
disable

{% if ppp_gw %}
[ip-pool]
gw-ip-address={{ppp_gw}}
{% if client_ip_pool %}
{{client_ip_pool}}
{% endif -%}

{% if client_ip_subnets %}
{% for sn in client_ip_subnets %}
{{sn}}
{% endfor %}
{% endif %}
{% endif -%}

{% if client_ipv6_pool %}
[ipv6-pool]
{% for prfx in client_ipv6_pool['prefix']: %}
{{prfx}}
{% endfor %}
{% for prfx in client_ipv6_pool['delegate-prefix']: %}
delegate={{prfx}}
{% endfor %}
{% endif %}

{% if dns %}
[dns]
{% if dns[0] %}
dns1={{dns[0]}}
{% endif -%}
{% if dns[1] %}
dns2={{dns[1]}}
{% endif -%}
{% endif %}

{% if dnsv6 %}
[ipv6-dns]
{% for srv in dnsv6: %}
{{srv}}
{% endfor %}
{% endif %}

{% if wins %}
[wins]
{% if wins[0] %}
wins1={{wins[0]}}
{% endif %}
{% if wins[1] %}
wins2={{wins[1]}}
{% endif -%}
{% endif -%}

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

{% if authentication['mode'] == 'radius' %}
[radius]
{% for rsrv in authentication['radiussrv']: %}
server={{rsrv}},{{authentication['radiussrv'][rsrv]['secret']}},\
req-limit={{authentication['radiussrv'][rsrv]['req-limit']}},\
fail-time={{authentication['radiussrv'][rsrv]['fail-time']}}
{% endfor %}
{% if authentication['radiusopt']['timeout'] %}
timeout={{authentication['radiusopt']['timeout']}}
{% endif %}
{% if authentication['radiusopt']['acct-timeout'] %}
acct-timeout={{authentication['radiusopt']['acct-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 -%}
gw-ip-address={{ppp_gw}}
verbose=1

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

[ppp]
verbose=1
check-ip=1
{% if not sesscrtl == 'disable' %}
single-session={{sesscrtl}}
{% endif -%}
{% if ppp_options['ccp'] %}
ccp=1
{% endif %}
{% if ppp_options['min-mtu'] %}
min-mtu={{ppp_options['min-mtu']}}
{% else %}
min-mtu={{mtu}}
{% endif %}
{% if ppp_options['mru'] %}
mru={{ppp_options['mru']}}
{% endif %}
{% if ppp_options['mppe'] %}
mppe={{ppp_options['mppe']}}
{% else %}
mppe=prefer
{% endif %}
{% if ppp_options['lcp-echo-interval'] %}
lcp-echo-interval={{ppp_options['lcp-echo-interval']}}
{% else %}
lcp-echo-interval=30
{% endif %}
{% if ppp_options['lcp-echo-timeout'] %}
lcp-echo-timeout={{ppp_options['lcp-echo-timeout']}}
{% endif %}
{% if ppp_options['lcp-echo-failure'] %}
lcp-echo-failure={{ppp_options['lcp-echo-failure']}}
{% else %}
lcp-echo-failure=3
{% endif %}
{% if ppp_options['ipv4'] %}
ipv4={{ppp_options['ipv4']}}
{% endif %}
{% if client_ipv6_pool %}
ipv6=allow
{% endif %}

{% if ppp_options['ipv6'] %}
ipv6={{ppp_options['ipv6']}}
{% if ppp_options['ipv6-intf-id'] %}
ipv6-intf-id={{ppp_options['ipv6-intf-id']}}
{% endif %}
{% if ppp_options['ipv6-peer-intf-id'] %}
ipv6-peer-intf-id={{ppp_options['ipv6-peer-intf-id']}}
{% endif %}
{% if ppp_options['ipv6-accept-peer-intf-id'] %}
ipv6-accept-peer-intf-id={{ppp_options['ipv6-accept-peer-intf-id']}}
{% endif %}
{% endif %}

mtu={{mtu}}

[pppoe]
verbose=1
{% if concentrator %}
ac-name={{concentrator}}
{% endif %}
{% if interface %}
{% for int in interface %}
interface={{int}}
{% if interface[int]['vlans'] %}
vlan-mon={{int}},{{interface[int]['vlans']|join(',')}}
interface=re:{{int}}\.\d+
{% endif %}
{% endfor -%}
{% endif -%}
{% if svc_name %}
service-name={{svc_name}}
{% endif -%}
pado-delay=0

{% if limits %}
[connlimit]
limit={{limits['conn-limit']}}
burst={{limits['burst']}}
timeout={{limits['timeout']}}
{% endif %}

[cli]
tcp=127.0.0.1:2001
'''

# pppoe 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", 2001))
            break
        except ConnectionRefusedError:
            time.sleep(0.5)
            cnt += 1
            if cnt == 100:
                raise("failed to start pppoe 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', cmd]).decode().strip()
        return ret
    except:
        return 1

# check ig local-ip is in client pool subnet


#
# inline helper functions end
#

def get_config():
    c = Config()
    if not c.exists('service pppoe-server'):
        return None

    config_data = {
        'concentrator': 'vyos-ac',
      'authentication': {
        'local-users': {
        },
          'mode': 'local',
        'radiussrv': {},
        'radiusopt': {}
      },
      'client_ip_pool': '',
      'client_ip_subnets': [],
      'client_ipv6_pool': {},
      'interface': {},
      'ppp_gw': '',
      'svc_name': '',
      'dns': [],
      'dnsv6': [],
      'wins': [],
      'mtu': '1492',
      'ppp_options': {},
      'limits': {},
      'snmp': 'disable',
      'sesscrtl': 'replace'
    }

    c.set_level('service pppoe-server')
    # general options
    if c.exists('access-concentrator'):
        config_data['concentrator'] = c.return_value('access-concentrator')
    if c.exists('service-name'):
        config_data['svc_name'] = c.return_value('service-name')
    if c.exists('interface'):
        for intfc in c.list_nodes('interface'):
            config_data['interface'][intfc] = {'vlans': []}
            if c.exists('interface ' + intfc + ' vlan-id'):
                config_data['interface'][intfc]['vlans'] += c.return_values(
                    'interface ' + intfc + ' vlan-id')
            if c.exists('interface ' + intfc + ' vlan-range'):
                config_data['interface'][intfc]['vlans'] += c.return_values(
                    'interface ' + intfc + ' vlan-range')
    if c.exists('local-ip'):
        config_data['ppp_gw'] = c.return_value('local-ip')
    if c.exists('dns-servers'):
        if c.return_value('dns-servers server-1'):
            config_data['dns'].append(c.return_value('dns-servers server-1'))
        if c.return_value('dns-servers server-2'):
            config_data['dns'].append(c.return_value('dns-servers server-2'))
    if c.exists('dnsv6-servers'):
        if c.return_value('dnsv6-servers server-1'):
            config_data['dnsv6'].append(
                c.return_value('dnsv6-servers server-1'))
        if c.return_value('dnsv6-servers server-2'):
            config_data['dnsv6'].append(
                c.return_value('dnsv6-servers server-2'))
        if c.return_value('dnsv6-servers server-3'):
            config_data['dnsv6'].append(
                c.return_value('dnsv6-servers server-3'))
    if c.exists('wins-servers'):
        if c.return_value('wins-servers server-1'):
            config_data['wins'].append(c.return_value('wins-servers server-1'))
        if c.return_value('wins-servers server-2'):
            config_data['wins'].append(c.return_value('wins-servers server-2'))
    if c.exists('client-ip-pool'):
        if c.exists('client-ip-pool start'):
            config_data['client_ip_pool'] = c.return_value(
                'client-ip-pool start')
            if c.exists('client-ip-pool stop'):
                config_data['client_ip_pool'] += '-' + re.search(
                    '[0-9]+$', c.return_value('client-ip-pool stop')).group(0)
            else:
                raise ConfigError('client ip pool stop required')
        if c.exists('client-ip-pool subnet'):
            config_data['client_ip_subnets'] = c.return_values(
                'client-ip-pool subnet')
    if c.exists('client-ipv6-pool prefix'):
        config_data['client_ipv6_pool'][
            'prefix'] = c.return_values('client-ipv6-pool prefix')
        if c.exists('client-ipv6-pool delegate-prefix'):
            config_data['client_ipv6_pool']['delegate-prefix'] = c.return_values(
                'client-ipv6-pool delegate-prefix')
    if c.exists('limits'):
        if c.exists('limits burst'):
            config_data['limits']['burst'] = str(
                c.return_value('limits burst'))
        if c.exists('limits timeout'):
            config_data['limits']['timeout'] = str(
                c.return_value('limits timeout'))
        if c.exists('limits connection-limit'):
            config_data['limits']['conn-limit'] = str(
                c.return_value('limits connection-limit'))
    if c.exists('snmp'):
        config_data['snmp'] = 'enable'
    if c.exists('snmp master-agent'):
        config_data['snmp'] = 'enable-ma'

    # authentication mode local
    if not c.exists('authentication mode'):
        raise ConfigError('pppoe-server authentication mode required')

    if c.exists('authentication mode local'):
        if c.exists('authentication local-users username'):
            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')

        # authentication mode radius servers and settings

    if c.exists('authentication mode radius'):
        config_data['authentication']['mode'] = 'radius'
        rsrvs = c.list_nodes('authentication radius-server')
        for rsrv in rsrvs:
            if c.return_value('authentication radius-server ' + rsrv + ' fail-time') == None:
                ftime = '0'
            else:
                ftime = str(
                    c.return_value('authentication radius-server ' + rsrv + ' fail-time'))
            if c.return_value('authentication radius-server ' + rsrv + ' req-limit') == None:
                reql = '0'
            else:
                reql = str(
                    c.return_value('authentication radius-server ' + rsrv + ' req-limit'))
            config_data['authentication']['radiussrv'].update(
                {
                    rsrv: {
                        'secret': c.return_value('authentication radius-server ' + rsrv + ' secret'),
                        'fail-time': ftime,
                        'req-limit': reql
                    }
                }
            )

        # 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'))
                        }
                    }
                )
            # filter-id is the internal accel default if attribute is empty
            # set here as default for visibility which may change in the future
            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('mtu'):
        config_data['mtu'] = c.return_value('mtu')

    # ppp_options
    ppp_options = {}
    if c.exists('ppp-options'):
        if c.exists('ppp-options ccp'):
            ppp_options['ccp'] = c.return_value('ppp-options ccp')
        if c.exists('ppp-options min-mtu'):
            ppp_options['min-mtu'] = c.return_value('ppp-options min-mtu')
        if c.exists('ppp-options mru'):
            ppp_options['mru'] = c.return_value('ppp-options mru')
        if c.exists('ppp-options mppe deny'):
            ppp_options['mppe'] = 'deny'
        if c.exists('ppp-options mppe require'):
            ppp_options['mppe'] = 'requre'
        if c.exists('ppp-options mppe prefer'):
            ppp_options['mppe'] = 'prefer'
        if c.exists('ppp-options lcp-echo-failure'):
            ppp_options['lcp-echo-failure'] = c.return_value(
                'ppp-options lcp-echo-failure')
        if c.exists('ppp-options lcp-echo-interval'):
            ppp_options['lcp-echo-interval'] = c.return_value(
                'ppp-options lcp-echo-interval')
        if c.exists('ppp-options ipv4'):
            ppp_options['ipv4'] = c.return_value('ppp-options ipv4')
        if c.exists('ppp-options ipv6'):
            ppp_options['ipv6'] = c.return_value('ppp-options ipv6')
        if c.exists('ppp-options ipv6-accept-peer-intf-id'):
            ppp_options['ipv6-accept-peer-intf-id'] = 1
        if c.exists('ppp-options ipv6-intf-id'):
            ppp_options['ipv6-intf-id'] = c.return_value(
                'ppp-options ipv6-intf-id')
        if c.exists('ppp-options ipv6-peer-intf-id'):
            ppp_options['ipv6-peer-intf-id'] = c.return_value(
                'ppp-options ipv6-peer-intf-id')
        if c.exists('ppp-options lcp-echo-timeout'):
            ppp_options['lcp-echo-timeout'] = c.return_value(
                'ppp-options lcp-echo-timeout')

    if len(ppp_options) != 0:
        config_data['ppp_options'] = ppp_options

    if c.exists(['session-control']):
        config_data['sesscrtl'] = c.return_value(['session-control'])

    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(
                'pppoe-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 c['authentication']['mode'] == 'radius':
        if len(c['authentication']['radiussrv']) == 0:
            raise ConfigError('radius server required')
        for rsrv in c['authentication']['radiussrv']:
            if c['authentication']['radiussrv'][rsrv]['secret'] == None:
                raise ConfigError(
                    'radius server ' + rsrv + ' needs a secret configured')

    # local ippool and gateway settings config checks

    if c['client_ip_subnets'] or c['client_ip_pool']:
        if not c['ppp_gw']:
            raise ConfigError('pppoe-server local-ip required')

    if c['ppp_gw'] and not c['client_ip_subnets'] and not c['client_ip_pool']:
        print ("Warning: No pppoe client IPv4 pool defined")


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(pppoe_config, trim_blocks=True)
    config_text = tmpl.render(c)
    open(pppoe_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', pppoe_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)