openvpn: T1548: initial rewrite with XML and Python

1 files changed, 903 insertions, 0 deletions

diff --git a/src/conf_mode/interface-openvpn.py b/src/conf_mode/interface-openvpn.py
new file mode 100755
index 000000000..1420cabe9
--- /dev/null
+++ b/src/conf_mode/interface-openvpn.py
@@ -0,0 +1,903 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2019 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 os
+import re
+import pwd
+import grp
+import sys
+import stat
+import copy
+import jinja2
+import psutil
+from ipaddress import ip_address,ip_network,IPv4Interface
+
+from signal import SIGUSR1
+from subprocess import Popen, PIPE
+
+from vyos.config import Config
+from vyos import ConfigError
+from vyos.validate import is_addr_assigned
+
+# Please be careful if you edit the template.
+config_tmpl = """
+### Autogenerated by interfaces-openvpn.py ###
+#
+# See https://community.openvpn.net/openvpn/wiki/Openvpn24ManPage
+# for individual keyword definition
+
+verb 3
+status /opt/vyatta/etc/openvpn/status/{{ intf }}.status 30
+writepid /var/run/openvpn/{{ intf }}.pid
+daemon openvpn-{{ intf }}
+
+dev-type {{ type }}
+dev {{ intf }}
+user {{ uid }}
+group {{ gid }}
+persist-key
+
+proto {% if 'tcp-active' in protocol -%}tcp-client{% elif 'tcp-passive' in protocol -%}tcp-server{% else %}udp{% endif %}
+
+{%- if local_host %}
+local {{ local_host }}
+{% endif %}
+
+{%- if local_port %}
+lport {{ local_port }}
+{% endif %}
+
+{%- if remote_port %}
+rport {{ remote_port }}
+{% endif %}
+
+{%- if remote_host %}
+{% for remote in remote_host -%}
+remote {{ remote }}
+{% endfor -%}
+{% endif %}
+
+{%- if shared_secret_file %}
+secret {{ shared_secret_file }}
+{% endif %}
+
+{%- if persistent_tunnel %}
+persist-tun
+{% endif %}
+
+{%- if mode %}
+{%- if 'client' in mode %}
+#
+# OpenVPN Client mode
+#
+client
+nobind
+{%- elif 'server' in mode %}
+#
+# OpenVPN Server mode
+#
+mode server
+tls-server
+keepalive {{ ping_interval }} {{ ping_restart }}
+management /tmp/openvpn-mgmt-intf unix
+
+{%- if server_topology %}
+topology {% if 'site-to-site' in server_topology %}p2p{% else %}{{ server_topology }}{% endif %}
+{% endif %}
+
+{% for ns in server_dns_nameserver -%}
+push "dhcp-option DNS {{ ns }}"
+{% endfor -%}
+
+{% for route in server_push_route -%}
+push "route {{ route }}"
+{% endfor -%}
+
+{%- if server_domain %}
+push "dhcp-option DOMAIN {{ server_domain }}"
+{% endif %}
+
+{%- if server_max_conn %}
+max-clients {{ server_max_conn }}
+{% endif %}
+
+{%- if bridge_member %}
+server-bridge nogw
+{%- else %}
+server {{ server_subnet }}
+{% endif %}
+
+{%- if server_reject_unconfigured %}
+ccd-exclusive
+{% endif %}
+
+{%- else %}
+#
+# OpenVPN site-2-site mode
+#
+ping {{ ping_interval }}
+ping-restart {{ ping_restart }}
+
+{%- if 'tap' in type %}
+ifconfig {{ local_address }} {{ local_address_subnet }}
+{% else %}
+ifconfig {{ local_address }} {{ remote_address }}
+{% endif %}
+
+{% endif %}
+{% endif %}
+
+{%- if tls_ca_cert %}
+ca {{ tls_ca_cert }}
+{% endif %}
+
+{%- if tls_cert %}
+cert {{ tls_cert }}
+{% endif %}
+
+{%- if tls_key %}
+key {{ tls_key }}
+{% endif %}
+
+{%- if tls_crl %}
+crl-verify {{ tls_crl }}
+{% endif %}
+
+{%- if tls_dh %}
+dh {{ tls_dh }}
+{% endif %}
+
+{%- if 'active' in tls_role %}
+tls-client
+{%- elif 'passive' in tls_role %}
+tls-server
+{% endif %}
+
+{%- if redirect_gateway %}
+push "redirect-gateway {{ redirect_gateway }}"
+{% endif %}
+
+{%- if compress_lzo %}
+compress lzo
+{% endif %}
+
+{%- if hash %}
+auth {{ hash }}
+{% endif %}
+
+{%- if encryption %}
+{%- if 'des' in encryption %}
+cipher des-cbc
+{%- elif '3des' in encryption %}
+cipher des-ede3-cbc
+{%- elif 'bf128' in encryption %}
+cipher bf-cbc
+keysize 128
+{%- elif 'bf256' in encryption %}
+cipher bf-cbc
+keysize 25
+{%- elif 'aes128' in encryption %}
+cipher aes-128-cbc
+{%- elif 'aes192' in encryption %}
+cipher aes-192-cbc
+{%- elif 'aes256' in encryption %}
+cipher aes-256-cbc
+{% endif %}
+{% endif %}
+
+{%- if auth %}
+auth-user-pass /tmp/openvpn-{{ intf }}-pw
+auth-retry nointeract
+{% endif %}
+
+{%- if client %}
+client-config-dir /opt/vyatta/etc/openvpn/ccd/{{ intf }}
+{% endif %}
+
+{% for option in options -%}
+{{ option }}
+{% endfor -%}
+
+{%- if server_2fa_authy_key %}
+plugin /usr/lib/authy/authy-openvpn.so https://api.authy.com/protected/json {{ server_2fa_authy_key }} nopam
+{% endif %}
+"""
+
+client_tmpl = """
+### Autogenerated by interfaces-openvpn.py ###
+
+ifconfig-push {{ ip }} {{ remote_netmask }}
+{% for route in push_route -%}
+push "route {{ route }}"
+{% endfor -%}
+
+{% for net in subnet -%}
+iroute {{ net }}
+{% endfor -%}
+
+{%- if disabled %}
+disable
+{% endif %}
+"""
+
+default_config_data = {
+    'address': [],
+    'auth_user': '',
+    'auth_pass': '',
+    'auth': False,
+    'bridge_member': [],
+    'compress_lzo': False,
+    'deleted': False,
+    'description': '',
+    'disabled': False,
+    'encryption': '',
+    'hash': '',
+    'intf': '',
+    'ping_restart': '60',
+    'ping_interval': '10',
+    'local_address': '',
+    'local_address_subnet': '',
+    'local_host': '',
+    'local_port': '',
+    'mode': '',
+    'options': [],
+    'persistent_tunnel': False,
+    'protocol': '',
+    'redirect_gateway': '',
+    'remote_address': '',
+    'remote_host': [],
+    'remote_port': '',
+    'server_2fa_authy_key': '',
+    'server_2fa_authy': [],
+    'client': [],
+    'server_domain': '',
+    'server_max_conn': '',
+    'server_dns_nameserver': [],
+    'server_push_route': [],
+    'server_reject_unconfigured': False,
+    'server_subnet': '',
+    'server_topology': '',
+    'shared_secret_file': '',
+    'tls': False,
+    'tls_ca_cert': '',
+    'tls_cert': '',
+    'tls_crl': '',
+    'tls_dh': '',
+    'tls_key': '',
+    'tls_role': '',
+    'type': 'tun',
+    'uid': 'nobody',
+    'gid': 'nogroup',
+}
+
+def subprocess_cmd(command):
+    p = Popen(command, stdout=PIPE, shell=True)
+    p.communicate()
+
+def get_config_name(intf):
+    cfg_file = r'/opt/vyatta/etc/openvpn/openvpn-{}.conf'.format(intf)
+    return cfg_file
+
+def fixup_permission(filename, permission=stat.S_IRUSR):
+    """
+    Check if the given file exists and change ownershit to root/vyattacfg
+    and appripriate file access permissions - default is user and group readable
+    """
+    if os.path.isfile(filename):
+        os.chmod(filename, permission)
+
+        # make file owned by root / vyattacfg
+        uid = pwd.getpwnam('root').pw_uid
+        gid = grp.getgrnam('vyattacfg').gr_gid
+        os.chown(filename, uid, gid)
+
+def checkCertHeader(header, filename):
+    """
+    Verify if filename contains specified header.
+    Returns True on success or on file not found to not trigger the exceptions
+    """
+    if not os.path.isfile(filename):
+        return True
+
+    with open(filename, 'r') as f:
+        for line in f:
+            if re.match(header, line):
+                return True
+
+    return False
+
+def get_config():
+    openvpn = copy.deepcopy(default_config_data)
+    conf = Config()
+
+    # determine tagNode instance
+    try:
+        openvpn['intf'] = os.environ['VYOS_TAGNODE_VALUE']
+    except KeyError as E:
+        print("Interface not specified")
+
+    print('Executing for interface ' + openvpn['intf'])
+
+    # Check if interface instance has been removed
+    if not conf.exists('interfaces openvpn ' + openvpn['intf']):
+        openvpn['deleted'] = True
+        return openvpn
+
+    # Check if we belong to any bridge interface
+    for bridge in conf.list_nodes('interfaces bridge'):
+        for intf in conf.list_nodes('interfaces bridge {} member interface'.format(bridge)):
+            if intf == openvpn['intf']:
+                openvpn['bridge_member'].append(intf)
+
+    # set configuration level
+    conf.set_level('interfaces openvpn ' + openvpn['intf'])
+
+    # retrieve authentication options - username
+    if conf.exists('authentication username'):
+        openvpn['auth_user'] = conf.return_value('authentication username')
+        openvpn['auth'] = True
+
+    # retrieve authentication options - username
+    if conf.exists('authentication password'):
+        openvpn['auth_pass'] = conf.return_value('authentication password')
+        openvpn['auth'] = True
+
+    # retrieve interface description
+    if conf.exists('description'):
+        openvpn['description'] = conf.return_value('description')
+
+    # interface device-type
+    if conf.exists('device-type'):
+        openvpn['type'] = conf.return_value('device-type')
+
+    # interface disabled
+    if conf.exists('disabled'):
+        openvpn['disabled'] = True
+
+    # data encryption algorithm
+    if conf.exists('encryption'):
+        openvpn['encryption'] = conf.return_value('encryption')
+
+    # hash algorithm
+    if conf.exists('hash'):
+        openvpn['hash'] = conf.return_value('hash')
+
+    # Maximum number of keepalive packet failures
+    if conf.exists('keep-alive failure-count') and conf.exists('keep-alive interval'):
+        fail_count = conf.return_value('keep-alive failure-count')
+        interval = conf.return_value('keep-alive interval')
+        openvpn['ping_interval' ] = interval
+        openvpn['ping_restart' ] = int(interval) * int(fail_count)
+
+    # Local IP address of tunnel - even as it is a tag node - we can only work
+    # on the first address
+    if conf.exists('local-address'):
+        openvpn['local_address'] = conf.list_nodes('local-address')[0]
+        if conf.exists('local-address {} subnet-mask'.format(openvpn['local_address'])):
+            openvpn['local_address_subnet'] = conf.return_value('local-address {} subnet-mask'.format(openvpn['local_address']))
+
+    # Local IP address to accept connections
+    if conf.exists('local-host'):
+        openvpn['local_host'] = conf.return_value('local-host')
+
+    # Local port number to accept connections
+    if conf.exists('local-port'):
+        openvpn['local_port'] = conf.return_value('local-port')
+
+    # OpenVPN operation mode
+    if conf.exists('mode'):
+        mode = conf.return_value('mode')
+        openvpn['mode'] = mode
+
+    # Additional OpenVPN options
+    if conf.exists('openvpn-option'):
+        openvpn['options'] = conf.return_values('openvpn-option')
+
+    # Do not close and reopen interface
+    if conf.exists('persistent-tunnel'):
+        openvpn['persistent_tunnel'] = True
+
+    # Communication protocol
+    if conf.exists('protocol'):
+        openvpn['protocol'] = conf.return_value('protocol')
+
+    # IP address of remote end of tunnel
+    if conf.exists('remote-address'):
+        openvpn['remote_address'] = conf.return_value('remote-address')
+
+    # Remote host to connect to (dynamic if not set)
+    if conf.exists('remote-host'):
+        openvpn['remote_host'] = conf.return_values('remote-host')
+
+    # Remote port number to connect to
+    if conf.exists('remote-port'):
+        openvpn['remote_port'] = conf.return_value('remote-port')
+
+    # OpenVPN tunnel to be used as the default route
+    # see https://openvpn.net/community-resources/reference-manual-for-openvpn-2-4/
+    # redirect-gateway flags
+    if conf.exists('replace-default-route'):
+        openvpn['redirect_gateway'] = 'def1'
+
+    if conf.exists('replace-default-route local'):
+        openvpn['redirect_gateway'] = 'local def1'
+
+    # Two Factor Authentication providers
+    # currently limited to authy
+    if conf.exists('2-factor-authentication authy api-key'):
+        openvpn['server_2fa_authy_key'] = conf.return_value('2-factor-authentication authy api-key')
+
+    # Authy users (must be email address)
+    for user in conf.list_nodes('server 2-factor-authentication authy user'):
+        # set configuration level
+        conf.set_level('interfaces openvpn ' + openvpn['intf'] + ' 2-factor-authentication authy user ' + user)
+        data = {
+            'user': user,
+            'country_code': '',
+            'mobile_number': ''
+        }
+
+        # Country calling codes
+        if conf.exists('country-calling-code'):
+            data['country_code'] = conf.return_value('country-calling-code')
+
+        # Mobile phone number
+        if conf.exists('phone-number'):
+            data['mobile_number'] = conf.return_value('phone-number')
+
+        openvpn['server_2fa_authy'].append(data)
+
+    # Topology for clients
+    if conf.exists('server topology'):
+        openvpn['server_topology'] = conf.return_value('server topology')
+
+    # Server-mode subnet (from which client IPs are allocated)
+    if conf.exists('server subnet'):
+        network = conf.return_value('server subnet')
+        tmp = IPv4Interface(network).with_netmask
+        # convert the network in format: "192.0.2.0 255.255.255.0" for later use in template
+        openvpn['server_subnet'] = tmp.replace(r'/', ' ')
+
+    # Client-specific settings
+    for client in conf.list_nodes('server client'):
+        # set configuration level
+        conf.set_level('interfaces openvpn ' + openvpn['intf'] + ' server client ' + client)
+        data = {
+            'name': client,
+            'disabled': False,
+            'ip': '',
+            'push_route': [],
+            'subnet': [],
+            'remote_netmask': ''
+        }
+
+        # note: with "topology subnet", this is "<ip> <netmask>".
+        #       with "topology p2p", this is "<ip> <our_ip>".
+        if openvpn['server_topology'] == 'subnet':
+            # we are only interested in the netmask portion of server_subnet
+            data['remote_netmask'] = openvpn['server_subnet'][1]
+        else:
+            # we need the server subnet in format 192.0.2.0/255.255.255.0
+            subnet = openvpn['server_subnet'].replace(' ', r'/')
+            # get iterator over the usable hosts in the network
+            tmp = ip_network(subnet).hosts()
+            # OpenVPN always uses the subnets first available IP address
+            data['remote_netmask'] = list(tmp)[0]
+
+        # Option to disable client connection
+        if conf.exists('disable'):
+            data['disabled'] = True
+
+        # IP address of the client
+        if conf.exists('ip'):
+            data['ip'] = conf.return_value('ip')
+
+        # Route to be pushed to the client
+        for network in conf.return_values('push-route'):
+            tmp = IPv4Interface(network).with_netmask
+            data['push_route'].append(tmp.replace(r'/', ' '))
+
+        # Subnet belonging to the client
+        for network in conf.return_values('subnet'):
+            tmp = IPv4Interface(network).with_netmask
+            data['subnet'].append(tmp.replace(r'/', ' '))
+
+        # Append to global client list
+        openvpn['client'].append(data)
+
+    # re-set configuration level
+    conf.set_level('interfaces openvpn ' + openvpn['intf'])
+
+    # DNS suffix to be pushed to all clients
+    if conf.exists('server domain-name'):
+        openvpn['server_domain'] = conf.return_value('server domain-name')
+
+    # Number of maximum client connections
+    if conf.exists('server max-connections'):
+        openvpn['server_max_conn'] = conf.return_value('server max-connections')
+
+    # Domain Name Server (DNS)
+    if conf.exists('server name-server'):
+        openvpn['server_dns_nameserver'] = conf.return_values('server name-server')
+
+    # Route to be pushed to all clients
+    if conf.exists('server push-route'):
+        network = conf.return_value('server push-route')
+        tmp = IPv4Interface(network).with_netmask
+        openvpn['server_push_route'] = tmp.replace(r'/', ' ')
+
+    # Reject connections from clients that are not explicitly configured
+    if conf.exists('server reject-unconfigured-clients'):
+        openvpn['server_reject_unconfigured'] = True
+
+    # File containing certificate for Certificate Authority (CA)
+    if conf.exists('tls ca-cert-file'):
+         openvpn['tls_ca_cert'] = conf.return_value('tls ca-cert-file')
+         openvpn['tls'] = True
+
+    # File containing certificate for this host
+    if conf.exists('tls cert-file'):
+         openvpn['tls_cert'] = conf.return_value('tls cert-file')
+         openvpn['tls'] = True
+
+    # File containing certificate revocation list (CRL) for this host
+    if conf.exists('tls crl-file'):
+         openvpn['tls_crl'] = conf.return_value('tls crl-file')
+         openvpn['tls'] = True
+
+    # File containing Diffie Hellman parameters (server only)
+    if conf.exists('tls dh-file'):
+         openvpn['tls_dh'] = conf.return_value('tls dh-file')
+         openvpn['tls'] = True
+
+    # File containing this host's private key
+    if conf.exists('tls key-file'):
+         openvpn['tls_key'] = conf.return_value('tls key-file')
+         openvpn['tls'] = True
+
+    # Role in TLS negotiation
+    if conf.exists('tls role'):
+         openvpn['tls_role'] = conf.return_value('tls role')
+         openvpn['tls'] = True
+
+    if conf.exists('shared-secret-key-file'):
+        openvpn['shared_secret_file'] = conf.return_value('shared-secret-key-file')
+
+    if conf.exists('use-lzo-compression'):
+        openvpn['compress_lzo'] = True
+
+    return openvpn
+
+def verify(openvpn):
+    if openvpn['deleted']:
+        return None
+
+    if not openvpn['mode']:
+        raise ConfigError('Must specify OpenVPN operation mode')
+
+    # Checks which need to be performed on interface rmeoval
+    if openvpn['deleted']:
+        # OpenVPN interface can not be deleted if it's still member of a bridge
+        if openvpn['bridge_member']:
+            raise ConfigError('Can not delete {} as it is a member interface of bridge {}!'.format(openvpn['intf'], bridge))
+
+    #
+    # OpenVPN client mode - VERIFY
+    #
+    if openvpn['mode'] == 'client':
+        if openvpn['local_port']:
+            raise ConfigError('Cannot specify "local-port" in client mode')
+
+        if openvpn['local_host']:
+            raise ConfigError('Cannot specify "local-host" in client mode')
+
+        if openvpn['protocol'] == 'tcp-passive':
+            raise ConfigError('Protocol "tcp-passive" is not valid in client mode')
+
+        if not openvpn['remote_host']:
+            raise ConfigError('Must specify "remote-host" in client mode')
+
+        if openvpn['tls_dh']:
+            raise ConfigError('Cannot specify "tls dh-file" in client mode')
+
+    #
+    # OpenVPN site-to-site - VERIFY
+    #
+    if openvpn['mode'] == 'site-to-site':
+        if not (openvpn['local_address'] or openvpn['bridge_member']):
+            raise ConfigError('Must specify "local-address" or "bridge member interface"')
+
+        if not openvpn['remote_address']:
+            raise ConfigError('Must specify "remote-address"')
+
+        if openvpn['local_address'] == openvpn['local_host']:
+            raise ConfigError('"local-address" cannot be the same as "local-host"')
+
+        for host in openvpn['remote_host']:
+            if host == openvpn['remote_address']:
+                raise ConfigError('"remote-address" cannot be the same as "remote-host"')
+
+        if openvpn['local_address'] == openvpn['remote_address']:
+            raise ConfigError('"local-address" and "remote-address" cannot be the same')
+
+        if openvpn['type'] == 'tap' and openvpn['local_address_subnet'] == '':
+            raise ConfigError('Must specify "subnet-mask" for local-address')
+
+    else:
+        if openvpn['local_address'] or openvpn['remote_address']:
+            raise ConfigError('Cannot specify "local-address" or "remote-address" in client-server mode')
+        elif openvpn['bridge_member']:
+            raise ConfigError('Cannot specify "local-address" or "remote-address" in bridge mode')
+
+    #
+    # OpenVPN server mode - VERIFY
+    #
+    if openvpn['mode'] == 'server':
+        if openvpn['protocol'] == 'tcp-active':
+            raise ConfigError('Protocol "tcp-active" is not valid in server mode')
+
+        if openvpn['remote_port']:
+            raise ConfigError('Cannot specify "remote-port" in server mode')
+
+        if openvpn['remote_host']:
+            raise ConfigError('Cannot specify "remote-host" in server mode')
+
+        if openvpn['protocol'] == 'tcp-passive' and len(openvpn['remote_host']) > 1:
+            raise ConfigError('Cannot specify more than 1 "remote-host" with "tcp-passive"')
+
+        if not openvpn['tls_dh']:
+            raise ConfigError('Must specify "tls dh-file" in server mode')
+
+        if not openvpn['server_subnet']:
+            if not openvpn['bridge_member']:
+                raise ConfigError('Must specify "server subnet" option in server mode')
+
+    else:
+        # checks for both client and site-to-site go here
+        if openvpn['server_reject_unconfigured']:
+            raise ConfigError('reject-unconfigured-clients is only supported in OpenVPN server mode')
+
+        if openvpn['server_topology']:
+            raise ConfigError('The "topology" option is only valid in server mode')
+
+        if (not openvpn['remote_host']) and openvpn['redirect_gateway']:
+            raise ConfigError('Cannot set "replace-default-route" without "remote-host"')
+
+    #
+    # OpenVPN common verification section
+    # not depending on any operation mode
+    #
+
+    # verify specified IP address is present on any interface on this system
+    if openvpn['local_host']:
+        if not is_addr_assigned(openvpn['local_host']):
+            raise ConfigError('No interface on system with specified local-host IP address: {}'.format(openvpn['local_host']))
+
+    # TCP active
+    if openvpn['protocol'] == 'tcp-active':
+        if openvpn['local_port']:
+            raise ConfigError('Cannot specify "local-port" with "tcp-active"')
+
+        if not openvpn['remote_host']:
+            raise ConfigError('Must specify "remote-host" with "tcp-active"')
+
+    # shared secret and TLS
+    if not (openvpn['shared_secret_file'] or openvpn['tls']):
+        raise ConfigError('Must specify one of "shared-secret-key-file" and "tls"')
+
+    if openvpn['shared_secret_file'] and openvpn['tls']:
+        raise ConfigError('Can only specify one of "shared-secret-key-file" and "tls"')
+
+    if openvpn['mode'] in ['client', 'server']:
+        if not openvpn['tls']:
+            raise ConfigError('Must specify "tls" in client-server mode')
+
+    #
+    # TLS/encryption
+    #
+    if not checkCertHeader('-----BEGIN OpenVPN Static key V1-----', openvpn['shared_secret_file']):
+        raise ConfigError('Specified shared-secret-key-file "{}" is not valid'.format(openvpn['shared_secret_file']))
+
+    if openvpn['tls']:
+        if not openvpn['tls_ca_cert']:
+            raise ConfigError('Must specify "tls ca-cert-file"')
+
+        if not (openvpn['mode'] == 'client' and openvpn['auth']):
+            if not openvpn['tls_cert']:
+                raise ConfigError('Must specify "tls cert-file"')
+
+            if not openvpn['tls_key']:
+                raise ConfigError('Must specify "tls key-file"')
+
+        if not checkCertHeader('-----BEGIN CERTIFICATE-----', openvpn['tls_ca_cert']):
+            raise ConfigError('Specified ca-cert-file "{}" is invalid'.format(openvpn['tls_ca_cert']))
+
+        if not checkCertHeader('-----BEGIN CERTIFICATE-----', openvpn['tls_cert']):
+            raise ConfigError('Specified cert-file "{}" is invalid'.format(openvpn['tls_cert']))
+
+        if not checkCertHeader('-----BEGIN (?:RSA )?PRIVATE KEY-----', openvpn['tls_key']):
+            raise ConfigError('Specified key-file "{}" is not valid'.format(openvpn['tls_key']))
+
+        if not checkCertHeader('-----BEGIN X509 CRL-----', openvpn['tls_crl']):
+            raise ConfigError('Specified crl-file "{} not valid'.format(openvpn['tls_crl']))
+
+        if not checkCertHeader('-----BEGIN DH PARAMETERS-----', openvpn['tls_dh']):
+            raise ConfigError('Specified dh-file "{}" is not valid'.format(openvpn['tls_dh']))
+
+        if openvpn['tls_role']:
+            if openvpn['mode'] in ['client', 'server']:
+                raise ConfigError('Cannot specify "tls role" in client-server mode')
+
+            if openvpn['tls_role'] == 'active':
+                if openvpn['protocol'] == 'tcp-passive':
+                    raise ConfigError('Cannot specify "tcp-passive" when "tls role" is "active"')
+
+                if openvpn['tls_dh']:
+                    raise ConfigError('Cannot specify "tls dh-file" when "tls role" is "active"')
+
+            elif openvpn['tls_role'] == 'passive':
+                if openvpn['protocol'] == 'tcp-active':
+                    raise ConfigError('Cannot specify "tcp-active" when "tls role" is "passive"')
+
+                if not openvpn['tls_dh']:
+                    raise ConfigError('Must specify "tls dh-file" when "tls role" is "passive"')
+
+    #
+    # Auth user/pass
+    #
+    if openvpn['auth']:
+        if not openvpn['auth_user']:
+            raise ConfigError('Username for authentication is missing')
+
+        if not openvpn['auth_pass']:
+            raise ConfigError('Password for authentication is missing')
+
+    #
+    # Client
+    #
+    subnet = openvpn['server_subnet'].replace(' ', '/')
+    for client in openvpn['client']:
+        if not ip_address(client['ip']) in ip_network(subnet):
+            raise ConfigError('Client IP "{}" not in server subnet "{}'.format(client['ip'], subnet))
+
+
+
+    return None
+
+def generate(openvpn):
+    if openvpn['deleted']:
+        return None
+
+    interface = openvpn['intf']
+    # create config directory on demand
+    directory = os.path.dirname(get_config_name(interface))
+    if not os.path.exists(directory):
+        os.mkdir(directory)
+
+    # create status directory on demand
+    if not os.path.exists(directory + '/status'):
+        os.mkdir(directory + '/status')
+
+    # fix permission on status directory
+    os.chmod(directory + '/status', stat.S_IRWXU|stat.S_IRWXG|stat.S_IROTH)
+    uid = pwd.getpwnam(openvpn['uid']).pw_uid
+    gid = grp.getgrnam(openvpn['gid']).gr_gid
+    os.chown(directory + '/status', uid, gid)
+
+    # create client config dir on demand
+    if not os.path.exists(directory + '/ccd/'):
+        os.mkdir(directory + '/ccd/')
+
+    # crete client config dir per interface on demand
+    if not os.path.exists(directory + '/ccd/' + interface):
+        os.mkdir(directory + '/ccd/' + interface)
+
+    os.chmod(directory + '/ccd/' + interface, stat.S_IRWXU|stat.S_IRWXG|stat.S_IROTH)
+    os.chown(directory + '/ccd/' + interface, uid, gid)
+
+    # Fix file permissons for keys
+    fixup_permission(openvpn['shared_secret_file'])
+    fixup_permission(openvpn['tls_key'])
+
+    # Generate User/Password authentication file
+    if openvpn['auth']:
+        auth_file = '/tmp/openvpn-{}-pw'.format(interface)
+        with open(auth_file, 'w') as f:
+            f.write('{}\n{}'.format(openvpn['auth_user'], openvpn['auth_pass']))
+
+        fixup_permission(auth_file)
+
+    # Generate client specific configuration
+    for client in openvpn['client']:
+        client_file = directory + '/ccd/' + interface + '/' + client['name']
+        tmpl = jinja2.Template(client_tmpl)
+        client_text = tmpl.render(client)
+        with open(client_file, 'w') as f:
+            f.write(client_text)
+
+    tmpl = jinja2.Template(config_tmpl)
+    config_text = tmpl.render(openvpn)
+    with open(get_config_name(interface), 'w') as f:
+        f.write(config_text)
+
+    return None
+
+
+def apply(openvpn):
+    interface = openvpn['intf']
+
+    pid = 0
+    pidfile = '/var/run/openvpn/{}.pid'.format(interface)
+    if os.path.isfile(pidfile):
+        pid = 0
+        with open(pidfile, 'r') as f:
+            pid = int(f.read())
+
+    # If tunnel interface has been deleted - stop service
+    if openvpn['deleted']:
+        directory = os.path.dirname(get_config_name(interface))
+
+        # we only need to stop the demon if it's running
+        # daemon could have died or killed by someone
+        if psutil.pid_exists(pid):
+            cmd  = 'start-stop-daemon --stop --quiet'
+            cmd += ' --pidfile ' + pidfile
+            subprocess_cmd(cmd)
+
+        # cleanup old PID file
+        if os.path.isfile(pidfile):
+            os.remove(pidfile)
+
+        # cleanup old configuration file
+        if os.path.isfile(get_config_name(interface)):
+            os.remove(get_config_name(interface))
+
+        # cleanup client config dir
+        if os.path.isdir(directory + '/ccd/' + interface):
+            os.remove(directory + '/ccd/' + interface + '/*')
+
+        return None
+
+    # Send SIGUSR1 to the process instead of creating a new process
+    if psutil.pid_exists(pid):
+        os.kill(pid, SIGUSR1)
+        return None
+
+    # No matching OpenVPN process running - maybe it got killed or none
+    # existed - nevertheless, spawn new OpenVPN process
+    cmd  = 'start-stop-daemon --start --quiet'
+    cmd += ' --pidfile ' + pidfile
+    cmd += ' --exec /usr/sbin/openvpn'
+    # now pass arguments to openvpn binary
+    cmd += ' --'
+    cmd += ' --config ' + get_config_name(interface)
+
+    # execute assembled command
+    subprocess_cmd(cmd)
+
+    return None
+
+if __name__ == '__main__':
+    try:
+        c = get_config()
+        verify(c)
+        generate(c)
+        apply(c)
+    except ConfigError as e:
+        print(e)
+        sys.exit(1)