Add check-vpn.py

check-vpn.py

@@ -0,0 +1,88 @@
+#!/usr/bin/env python3
+
+import os
+import signal
+import subprocess
+import sys
+import time
+
+PIDFILE = '/var/run/vpnclient.pid'
+VPNIF = 'tun0'
+DEFAULT_REMOTE_HOST = '4.2.2.2'
+VPN_ROUTE_PREFIX = '10.'
+PROCESS_SEARCH_STRING = 'vpnprov'
+
+
+def check_connection(remote_host=DEFAULT_REMOTE_HOST) -> bool:
+    """ Check internet connection by pinging remote_host """
+    ping_proc = subprocess.run(['ping', '-c', '5', remote_host])
+    return ping_proc.returncode == 0
+
+
+def get_route(remote_host=DEFAULT_REMOTE_HOST):
+    """ Get first route used in tracerouting to remote_host"""
+    out = subprocess.check_output(
+        ['traceroute', '-m', '1', remote_host],
+        stderr=subprocess.DEVNULL
+    ).decode()
+    first_route = out.split()[1]
+    return first_route
+
+
+def run_vpn():
+    delete_routes()
+    subprocess.run(['sh', '/etc/netstart', VPNIF])
+
+
+def kill_vpn_client(vpnclient_pid):
+    try:
+        os.kill(vpnclient_pid, signal.SIGTERM)
+    except ProcessLookupError:
+        pass
+    time.sleep(5)
+    delete_routes()
+
+
+def delete_routes():
+    out = subprocess.check_output(["netstat", "-rn"]).decode()
+    out = out.splitlines()
+    for line in out:
+        if VPNIF in line:
+            route = line.split()[0]
+            subprocess.run(['route', 'delete', route])
+
+
+def get_pid_by_str(search_str):
+    """ Search pid by its command line """
+    out = subprocess.check_output(['ps', '-A', '-o pid,command'])
+    out = out.decode()
+
+    for line in out.splitlines():
+        pid, cmd = line.strip().split(' ', 1)
+        if search_str in cmd.lower():
+            return int(pid)
+
+    return None
+
+
+def write_pid(pid, pidfile):
+    with open(pidfile, 'w') as pfile:
+        pfile.write('%s\n' % str(pid))
+
+
+def main():
+    vpn_client_pid = get_pid_by_str(PROCESS_SEARCH_STRING)
+
+    if vpn_client_pid is not None:
+        if not (check_connection() and get_route().startswith(VPN_ROUTE_PREFIX)):
+            kill_vpn_client(vpn_client_pid)
+            run_vpn()
+
+    else:
+        run_vpn()
+
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(main())