#!/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
ippool
{% if client_ipv6_pool %}
ipv6pool
{% 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 %}
{% if authentication['mode'] == 'radius' %}
radius
{% 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

[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 %}

{% 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 %}
[dnsv6]
{% for srv in dnsv6: %}
dns={{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']}}
{% endif -%}
{% endif %}

[ppp]
verbose=1
check-ip=1
single-session=replace
{% 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 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}}
{% endfor %}
{% endif %}
{% if svc_name %}
service-name={{svc_name}}
{% endif %}
pado-delay=0
# maybe: called-sid, tr101, padi-limit etc.

{% 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'
  }

  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'):
    config_data['interface'] = c.return_values('interface')
  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('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

  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

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

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

  ### activate as soon as it is clear what to do migrate or depricate. 
  #if c['client_ip_pool']:
  #  print ("Warning: client-ip-pool (start|stop) is depricated, please use client-ip-pool subnet")
  #  sl.syslog(sl.LOG_NOTICE, "client-ip-pool start stop is depricated, please use client-ip-pool subnet")

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)