Develop Reference

Python script to check openvpn server is active or dead

I am looking at the python program which will check if list of remote openvpn servers are really working!!
I tried the following code but no luck. after connecting the vpn server the control is not passing back to execute next line unless pressed ctrl+c. How to check below:
If the openvpn is connecting server then print active message
Else print not active message.
The whole thing is in a loop and I want to run in a virtual environment.
Code is given below
path = tempfile.mkstemp()
print('Path:',path)
f = open(path, 'w')
f.write(base64.b64decode(winner[-1]).decode('utf-8'))
f.close()
x = subprocess.Popen(['sudo', 'openvpn', '--config', path])
print("\n\n Pid:",x.pid)
try:
print('############ inside try block############', x.pid)
while True:
print('############ inside while try block############', x.pid)
time.sleep(60)
if (x.wait() == 0):
# died_serv_list.append(winner)
print('\nDead server found....Exiting.....\n')
return
print('############terminating the current prosses############', x.pid)
x.send_signal(9)
# y = subprocess.Popen(['sudo', 'kill', '-9', x.pid])
break
# termination with Ctrl+C
except: #here issue only works with ctrl+C
try:
print('\n\n\n Nice server found...\n\n')
good_serv_list.append(winner)
print('we are inside exept.')
x.kill()
except:
pass
while x.poll() != 0:
print('\n\n Donot know what the hell is this')
time.sleep(1)
print('\nVPN terminated')

How to timeout Paramiko sftp.put() with signal module or other in Python?

I would like timeout the function sftp.put(), I have tried with signal Module but the script doesn't die if the upload time is over 10s.
I use that to transfer files by ssh (paramiko).
[...]
def handler(signum, frame):
print 'Signal handler called with signal', signum
raise IOError("Couldn't upload the fileeeeeeeeeeee!!!!")
[...]
raspi = paramiko.SSHClient()
raspi.set_missing_host_key_policy(paramiko.AutoAddPolicy())
raspi.connect(ip , username= "", password= "" , timeout=10)
sftp = raspi.open_sftp()
[...]
signal.signal(signal.SIGALRM, handler)
signal.alarm(10)
sftp.put(source, destination , callback=None, confirm=True)
signal.alarm(0)
raspi.close()
[...]
Update 1:
I want to abort the transfer if the server stops responding for a while. Actually, my python script check (in loop) any files in a folder, and send it to this remote server. But in the problem here I want to leave this function in the case of the server become inaccessible suddenly during a transfer (ip server changing, no internet anymore,...). But when I simulate a disconnection, the script stays stuck at this function sftp.put anyway...)
Update 2:
When the server goes offline during a transfer, put() seems to be blocked forever. This happens with this line too:
sftp.get_channel().settimeout(xx)
How to do when we lose the Channel?
Update 3 & script goal
Ubuntu 18.04
and paramiko version 2.6.0
Hello,
To follow your remarks and questions, I have to give more details about my very Ugly script, sorry about that :)
Actually, I don’t want to have to kill a thread manually and open a new one. For my application I want that the script run totally in autonomous, and if something wrong during the process, it can still go on. For that I use the Python exception handling. Everything does what I want except when the remote server going off during a transfer: The script stays blocked in the put() function, I think inside a loop.
Below, the script contains in total 3 functions to timeout this thanks to your help, but apparently nothing can leave this damned sftp.put()! Do you have some new idea ?
Import […]
[...]
def handler(signum, frame):
print 'Signal handler called with signal', signum
raise IOError("Couldn't upload the fileeeeeeeeeeee!!!!")
def check_time(size, file_size):
global start_time
if (time.time() - start_time) > 10:
raise Exception
i = 0
while i == 0:
try:
time.sleep(1) # CPU break
print ("go!")
#collect ip server
fichierIplist = open("/home/robert/Documents/iplist.txt", "r")
file_lines = fichierIplist.readlines()
fichierIplist.close()
last_line = file_lines [len (file_lines)-1]
lastKnowip = last_line
data = glob.glob("/home/robert/Documents/data/*")
items = len(data)
if items != 0:
time.sleep(60) #anyway
print("some Files!:)")
raspi = paramiko.SSHClient()
raspi.set_missing_host_key_policy(paramiko.AutoAddPolicy())
raspi.connect(lastKnowip, username= "", password= "" , timeout=10)
for source in data: #Upload file by file
filename = os.path.basename(source) #
destination = '/home/pi/Documents/pest/'+ filename #p
sftp = raspi.open_sftp()
signal.signal(signal.SIGALRM, handler)
signal.alarm(10)
sftp.get_channel().settimeout(10)
start_time = time.time()
sftp.put(source, destination, callback=check_time)
sftp.close()
signal.alarm(0)
raspi.close()
else:
print("noFile!")
except:
pass

If you want to timeout, when the server stops responding:
set the timeout argument of SSHClient.connect (your doing that already),
and set sftp.get_channel().settimeout as already suggested by #EOhm
If you want to timeout even when the server is responding, but slowly, implement the callback argument to abort the transfer after certain time:
start_time = time.time()
def check_time(size, file_size):
global start_time
if (time.time() - start_time) > ...:
raise Exception
sftp.put(source, destination, callback=check_time)
This won't cancel the transfer immediately. To optimize transfer performance, Paramiko queues the write requests to the server. Once you attempt to cancel the transfer, Paramiko has to wait for the responses to those requests in SFTPFile.close() to clear the queue. You might solve that by using SFTPClient.putfo() and avoiding calling the SFTPFile.close() when the transfer is cancelled. But you won't be able to use the connection afterwards. Of course, you can also not use the optimization, then you can cancel the transfer without delays. But that kind of defies the point of all this, doesn't it?
Alternatively, you can run the transfer in a separate thread and kill the thread if it takes too long. Ugly but sure solution.

Use sftp.get_channel().settimeout(s) for that instead.

After trying a lot of things and with your help and advice, I have found a reliable solution for what I wanted. I execute sftp.put in a separate Thread and my script do what I want.
Many thanks for your help
Now if the server shuts down during a transfer, after 60 sec, my script goes on using:
[...]
import threading
[...]
th = threading.Thread(target=sftp.put, args=(source,destination))
th.start()
h.join(60)
[...]

Python program pauses when server runs

I am making a python program that communicates with a minecraft server and tells it to start, stop, or any other commands. The program reads an email and executes the command given from the email. When the program enters the command to start the server, it freezes the python program until the minecraft server is stopped.
I have tried to have the program open a batch file that starts the server, but then I don't have any way of making the program turn it off, or type in commands, or read the console.
if data[0]+data[1]+data[2]+data[3]+data[4]+data[5] == 'start ':
comm = data.replace('start ','')
try:
mb = int(float(comm)*1024)
#calls the command to start the server
call('java -Xmx' + str(mb) + 'M -Xms' + str(mb) + 'M -jar server.jar nogui')
#program freezes here until server is stopped
except Exception:
call('java -Xmx1024M -Xms1024M -jar server.jar nogui')
print("started server")
elif data == "stop server" or data == "stop":
call('stop')
elif data[0]+data[1]+data[2]+data[3]+data[4] == 'call ':
comm = data.replace('call ','')
call(comm)
print("called command")
elif data[0]+data[1]+data[2] == 'op ':
comm = data
call(comm)
print("op player")
else:
print("not a command")
deletemail(mail,i)
print("deleted item")
I expected to see the program continue and respond to emails, but it froze instead. The program continued off normally after the server was stopped. I know this isn't an error, but is there a way to get the python program to continue while the server is running?

Its is better practice to use subprocess to handle this. You can use popen which will allow you to continue to run your script and send in commands. Here is a good answer on using popen that shows how to send in commands.

wrong in my script for download?

I write this script
import urllib
urllib.urlretrieve("URL","path\ name.jpg")
It's working
But if there is no internet it's make wrong
I want it if there is no internet. wait to connect by internet then work again

You can write something like this:
def wait_for_internet_connection():
while True:
try:
response = urllib2.urlopen('http://google.com',timeout=1)
return
except urllib2.URLError:
pass
def main():
#your code here
wait_for_internet_connection()
main()
The while loop will execute until there's an active internet connection, then executes your code.

Python SOCKET infinite loop: stack overflow

I'm creating a game in the Blender Game Engine. And I have coded an IRC script which works fine on OS X and Linux distros. The output is similar to this:
Logging in...
LOGIN_ERROR
LOGIN_ERROR
LOGIN_ERROR
LOGIN_ERROR
LOGIN_ERROR
LOGIN_ERROR
<name> has joined.
Logged in!
And then I can call my sendmsg() function to send messages to the IRC channel.
This is the error I get when I try to run on Windows 7:
My python IRC code:
http://pastebin.com/aG6TwTir
Ignore the "bge" references. Those variables and such are filled from the game engine.
In the game engine, I call login() once, and it spits out "LOGIN_ERROR" so I know it's trying to connect, and then it will connect, therefore not throwing an exception and ending the function.
In OS X and Linux, it runs perfectly and seemlessly in the background while the player can continue to play as it connects.
In windows 7, it throws that error.
So I guess what needs to happen is a way to wait for the script to connect to the server. Then once connected, I can send the login information and join the channel.
So how do I wait for the connection?
FYI: I have the sockets non-blocking, since the script needs to run on the same thread as the game engine, on every frame.
Main() is run every frame, not the whole script. At the menu, it executes the script and calls login(). Then once in the game, it will call Main() every frame.
Oh and I'm using Python 3.3.
Any help is greatly apreciated! ^_^
EDIT:
How do I handle this exception?

This code:
def login():
...
try:
...
except:
...
login() # <===
recursively calls itself; given a high enough number of login failures, depending on the stack size limit (which depends on platform I guess), you'll get a stack overflow.
See also: Setting stacksize in a python script
Although I would always just avoid recursion and use looping instead, unless I know in advance that the recursion depth will never be more than ~100:
while True:
try:
do_login()
except: # NOTE: USE A SPECIFIC EXCEPTION CLASS HERE, BTW
continue
else:
break

You have recursion happening in your error handling
def login():
#print('login')
# Bind the socket
try:
s.connect((HOST, PORT))
# Send login info
s.send(bytes('NICK %s\r\n' % NICK, 'UTF-8'))
s.send(bytes('USER %s %s bla :%s\r\n' % (IDENT, HOST, REALNAME), 'UTF-8'))
s.send(bytes('JOIN %s\r\n' % CHAN, 'UTF-8'));
print('Logging in...')
chatlog('Logging in...')
except:
print('LOGIN_ERROR')
login()
So in your function login() you have a try, then in the except you call login() again. This will just loop over and over again if the login fails.