#!/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
chap-secrets
auth_pap
auth_chap_md5
auth_mschap_v1
auth_mschap_v2
pppd_compat
shaper
net-snmp
connlimit
{% if authentication['mode'] == 'radius' %}
radius
{% endif %}

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

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

[snmp]
master=1

[client-ip-range]
disable

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

{% if dns %}
[dns]
{% if dns[0] %}
dns1={{dns[0]}}
{% endif %}
{% if dns[1] %}
dns2={{dns[1]}}
{% endif %}
{% 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]}}
{% endfor %}
timeout=10
acct-timeout=3
gw-ip-address={{ppp_gw}}
verbose=1
{% endif %}

[ppp]
verbose=1
min-mtu={{mtu}}
mtu={{mtu}}
mru=1400
check-ip=1
mppe=prefer
ipv4=require
check-ip=1
single-session=replace
mppe=prefer
lcp-echo-interval=30
lcp-echo-failure=3

[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 %}


[connlimit]
limit=10/min
burst=3
timeout=60

[cli]
tcp=127.0.0.1:2001
'''

### pppoe chap secrets
chap_secrets_conf = '''
# username  server  password  acceptable local IP addresses
{% for user in authentication['local-users'] %}
{% if authentication['local-users'][user]['state'] == 'enabled' %}
{{user}}\t*\t{{authentication['local-users'][user]['passwd']}}\t{{authentication['local-users'][user]['ip']}}
{% 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

### 
# 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'     : {}
    },
    'client_ip_pool'  : '',
    'interface'       : [],
    'ppp_gw'          : '',
    'svc_name'        : '',
    'dns'             : [],
    'wins'            : [],
    'mtu'             : '1492'
  }

  c.set_level('service pppoe-server')
    
  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('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')

  #### authentication mode local
  if c.exists('authentication'):
    if c.return_value('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' : '',
                'state'  : 'enabled',
                'ip'     : '*'
              }
            }
          )
          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')
   
    ### authentication mode radius
    if c.return_value('authentication mode') == 'radius':
      config_data['authentication']['mode'] = 'radius'
      rsrvs = c.list_nodes('authentication radius-server')
      for rsrv in rsrvs:
        config_data['authentication']['radiussrv'].update(
          {
            rsrv  : str(c.return_value('authentication radius-server ' + rsrv + ' key')) 
          }
        )

  if c.exists('mtu'):
    config_data['mtu'] = c.return_value('mtu')

  return config_data

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

  for usr in c['authentication']['local-users']:
    if not c['authentication']['local-users'][usr]:
      raise ConfigError('user ' + usr + ' has no password set')

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

  if c['authentication']['mode'] == 'radius':
    if len(c['authentication']['radiussrv']) == 0:
      raise ConfigError('radius server required')

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)
  sl.syslog(sl.LOG_NOTICE, pppoe_config + ' written')

  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 c['state'] == 'update':
   # accel_cmd('restart')
   # sl.syslog(sl.LOG_NOTICE, "reloading config via daemon restart") 
   # ## check that config reload actually works

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