Develop Reference

Python not catching exceptions

I have this script:
#!/usr/bin/env python
#import needed modules
import telnetlib
import time
#define variables
HOST = "xxxxxx"
user = "xxxxxx"
password = "xxxxxx"
#open telnet connection
tn = telnetlib.Telnet(HOST, 10800)
time.sleep(2)
#check for initial screen and press enter to go to login
tn.read_until("Device")
tn.write("\r\n")
time.sleep(2)
#Wait for username prompt and enter user/pass
try:
tn.read_until("User Name:",5)
except:
#Timeout looking for Username prompt
print "CRITICAL: User Name prompt never arrived"
exit(2)
tn.write(user + "\r\n")
tn.read_until("Password :")
tn.write(password + "\r\n")
time.sleep(2)
#wait for logout prompt
try:
tn.read_until("7<Logout >",5)
except:
#Timeout looking for successful login
print "CRITICAL: Did not login successfully"
exit(2)
#Logout and close connection
tn.write("7\r")
tn.close()
#Exit with success
print "OK: Test login to MWA Succeeded"
exit(0)
No matter what I do, no exceptions are caught. I changed the read_until looking for "User Name:" to just some garbage characters and it still just gets to the end of the code. I'm hoping I'm just doing something very stupid and not an issue with telnetlib.
Thanks!

Per the docs:
Read until a given string, expected, is encountered or until timeout
seconds have passed.
When no match is found, return whatever is available instead, possibly
the empty string. Raise EOFError if the connection is closed and no
cooked data is available.
Check the return value in the try block, and if this value does not match your expectations, raise on your own to trigger the except case.

getpass.getpass() function in Python not working?

Running on Windows 7 and using PyCharm 2016.2.3 if that matters at all.
Anyway, I'm trying to write a program that sends an email to recipients, but I want the console to prompt for a password to login.
I heard that getpass.getpass() can be used to hide the input.
Here is my code:
import smtplib
import getpass
import sys
print('Starting...')
SERVER = "localhost"
FROM = "my#email.com"
while True:
password = getpass.getpass()
try:
smtpObj = smtplib.SMTP(SERVER)
smtpObj.login(FROM, password)
break
except smtplib.SMTPAuthenticationError:
print("Wrong Username/Password.")
except ConnectionRefusedError:
print("Connection refused.")
sys.exit()
TO = ["your#email.com"]
SUBJECT = "Hello!"
TEXT = "msg text"
message = """\
From: %s
To: %s
Subject: %s
%s
""" % (FROM, ", ".join(TO), SUBJECT, TEXT)
smtpObj.sendmail(FROM, TO, message)
smtpObj.close()
print("Successfully sent email")
But when I run my code, here is the output:
Starting...
/Nothing else appears/
I know the default prompt for getpass() is 'Password:' but I get the same result even when I pass it a prompt string.
Any suggestions?
EDIT: The code continues to run indefinitely after it prints the string, but nothing else appears and no emails are sent.

For PyCharm 2018.3
Go to 'Edit Configurations' and then select 'Emulate terminal in output console'.
Answer provided by Abhyudaya Sharma

The problem you have is that you are launching it via PyCharm, which has it's own console (and is not the console used by getpass)
Running the code via a command prompt should work

python pexpect & pxssh with sudo and EOF

I make ssh login with this script:
import pxssh
import pexpect
s = pxssh.pxssh()
hostname = 'localhost'
username = 'py_worker'
password = 'nicejob'
s.login (hostname, username, password)
print "logged in"
Then I want to run some program which in some case may require sudo password and in some case may not require. So I want a scrip which could provide sudo password in those cases when required and just run the program if sudo is not asked.
I thought this code could handle:
s.sendline('sudo apt-get check')
i=s.expect(['password', pexpect.EOF])
if i==0:
print "I give password"
s.sendline("nicejob")
s.prompt()
elif i==1:
print "EOF cought"
s.prompt()
print s.before
Could someone help with code lines which could handle sudo correctly?

thanks for asking this, it helped me.
youll probably need to flesh out the exceptions and re for the rootprompt but here you go.
def sudo(s,password):
rootprompt = re.compile('.*[$#]')
s.sendline('sudo -s')
i = s.expect([rootprompt,'assword.*: '])
if i==0:
print "didnt need password!"
pass
elif i==1:
print "sending password"
s.sendline(password)
j = s.expect([rootprompt,'Sorry, try again'])
if j == 0:
pass
elif j == 1:
raise Exception("bad password")
else:
raise Exception("unexpected output")
s.set_unique_promp

Client socket not receiving data correctly

I've tried looking about for an answer but I can't seem to find one that answers my specific problem.
Perhaps I don't know how to articulate the problem correctly.
I think I've pinpointed what it is, but the thing is I just don't know how to fix it.
EDIT: I was trying to use two clients on one TCP Socket. Can't do that. I'll have to think of another way. Solved, I guess.
So what I've got is are
1: Two Clients
2: One Server
The objective is this:
Have the server distribute new usernames to all the clients as they connect.
This is what happens when I run the program:
Server: Define Host, and Port, initialize it. Check
Client 1: Connects to the server. Check
Client 1: Once connected, sends a string to the server. Check
Server: Receives a string, checks if the string is in a list is created. If it is: Pass, if it's not, send to everyone the new string. Check
Client 1: [Now waiting to receive data] Recieves data, checks if the string received matches the one it sent. If it does, print("It's one of ours!"), else, make the new string = to Client 2 Username. Check
Client 2: Connects to server: Check
Server: [If it receives a string, prints it.] (Works) Checks if the new string is in the list. [It isn't] So It sends the new username to everyone, and then prints ("Sent to everyone") Check
But, when client 2 receives the string, it prints it. However, client 1 never recives the string.
And when running client one in IDLE, I noticed something went wrong as Client 1 tried to receive the data. (The while loop that the data = s.recv began looping real fast, instead of waiting)
I've asked around in chat, but it seems nobody's around right now. I've tried looking this up but I really can't find an answer. What I suspect is happening is that when my server sends to 'connection' the second time, it somehow overrides the original client connection.
Here's my server code:
from socket import *
import threading
import os
import csv
Username_List = []
host = input("Host: ")
port = input("Port: ")
ss = socket(AF_INET,SOCK_STREAM)
ss.bind((host,int(port)))
ss.listen(2)
while True:
try:
connection,address = ss.accept()
data = connection.recv(1024)
if data:
translated_data = data.decode()
print(translated_data)
if translated_data in Username_List:
pass
else:
Username_List.append(translated_data)
connection.sendall(translated_data.encode())
print("Sent new username to everyone")
except IOError:
connection.close()
print("An exception with a connected user occured")
break
And here is my client code: [The only difference between client 1 and 2 is I changed the username variable]
# Sample Username Client Service Handler.
from socket import *
import threading
import os
import csv
Username = ("Owatch")
host = input("Host: ")
port = input("Port: ")
try:
ss = socket(AF_INET,SOCK_STREAM)
ss.connect((host,int(port)))
except IOError:
print("Aw no man")
ss.send(Username.encode())
while True:
try:
print("Waiting to Recieve Data")
data = ss.recv(1024)
if data:
translated_data = data.decode()
print(translated_data)
if translated_data == Username:
print("It's one of ours!")
else:
Client_Username = translated_data
print (Client_Username)
except Exception as e:
print (vars(e))
If you could please help I'd be grateful.
If you know of an answer to my question that's already been asked, please tell me and I'll remove this post to avoid breaking rules. Thanks!

Right then I started with what you had then changed it till it worked what I've done is created a client class which starts a thread with each connection and adds it to a list of threads (please if I'm doing something horribly wrong smarter people correct me), the thread runs gets some data checks if that's in the list of user names if its not sends out a message to all the clients in the thread list with that name then the thread just chills out. Anyway on to the code.
SERVER!!!
import csv
class client(threading.Thread):
Username_List = []
def __init__(self, conn):
super(client, self).__init__()
self.conn = conn
def run(self):
print "Client thread started"
data = self.conn.recv(1024)
print "Received: {0}".format(data)
if data in client.Username_List:
self.send_msg("Welcome Back!")
else:
for cnt in threadz:
cnt.send_msg(data)
print("Sent new username to everyone")
client.Username_List.append(data)
while True:
# dont need nothing now
pass
def send_msg(self,msg):
self.conn.send(msg)
host = input("Host: ")
port = input("Port: ")
ss = socket() #AF_INET,SOCK_STREAM)
ss.bind((host,int(port)))
print "Server Opening on port: {0}".format(port)
ss.listen(2)
threadz = []
print "Begining Wait for connections"
while True:
try:
connection, address = ss.accept()
print "Got ONE!"
c = client(connection)
print "Recevied connection from:{0} On port:{1}".format(address[0],address[1])
c.start()
threadz.append(c)
print "Client appended to threadz, currently {0} threadz active".format(len(threadz))
except IOError,KeyboardInterrupt:
connection.close()
print("An exception with a connected user occured")
break
The CLIENT:
# Sample Username Client Service Handler.
from socket import *
import threading
import os
import csv
Username = ("ShyGuy")
host = input("Host: ")
port = input("Port: ")
try:
ss = socket() #AF_INET,SOCK_STREAM)
ss.connect((host,int(port))) #I was using ("localhost",1234) for testing
ss.send(Username)
except IOError:
print("Aw no man")
print("Waiting to Recieve Data")
while True:
try:
data = ss.recv(1024)
if data:
translated_data = data.decode()
print(translated_data)
if translated_data == Username:
print"Name: {0} has been registered on server!".format(translated_data)
else:
Client_Username = translated_data
print "New client name received: {0}".format(Client_Username)
except Exception as e:
print (vars(e))
That works on python 2.7 with two clients locally. Needs to use a semaphore to stop the threads printing at the same time as the main server loop prints: http://en.wikipedia.org/wiki/Semaphore_(programming)
This code does nothing graceful with client disconnects, but once you can work with the exceptions that a raised when that happens I'm sure you'll learn some more.

Python script progress email

I have a Python script that loops through a list of 8 different machines and does a copy, execute, and test. I would like to receive an email after each loop. **I'm not sure what to google for this. I would appreciate any ideas that will help me with my task.
I am aware of the smtplib module, just not how to perform a certain task with it.
I did indeed check the handy search engine and found no previous questions that provided answers
Question: how would one break in the middle of a loop, send an email, then continue with the loop??????
I have an email when the script starts and an email when the script ends. I just want to be notified as the script progresses or if it fails.
Thank you in advance.

You're looking for Python's smtp library.
The example from the documentation is this:
import smtplib
def prompt(prompt):
return raw_input(prompt).strip()
fromaddr = prompt("From: ")
toaddrs = prompt("To: ").split()
print "Enter message, end with ^D (Unix) or ^Z (Windows):"
# Add the From: and To: headers at the start!
msg = ("From: %s\r\nTo: %s\r\n\r\n"
% (fromaddr, ", ".join(toaddrs)))
while 1:
try:
line = raw_input()
except EOFError:
break
if not line:
break
msg = msg + line
print "Message length is " + repr(len(msg))
server = smtplib.SMTP('localhost')
server.set_debuglevel(1)
server.sendmail(fromaddr, toaddrs, msg)
server.quit()

Use the built-in email package to create your message if there's anything nonstandard you need to do with MIMEtypes/etc. Use the built-in smtplib package to send it (and create it if you don't have to do anything fancy).