Python recv Loop

Question

I am try to display data that is sent over a socket via an iteration from a loop. The way I have it at the moment isn't working on the Admin client. What should I do to fix my loop? Thank you

Admin thread in the server -

def HandleAdmin(adminSocket,):
 global addressList
 (c,a) = adminSocket.accept() 
 ts = ssl.wrap_socket(c, certfile="5cc515_server.crt",
 keyfile="5cc515_server.key",
 server_side=True,
 cert_reqs=ssl.CERT_REQUIRED,
 ca_certs="5cc515-root-ca.cer")
 if ts.recv(80).decode() == 'Hello\r\n':
 ts.send('Admin-Greetings\r\n'.encode()) 
 if ts.recv(80).decode() == 'Who\r\n':
 for i in addressList:
 ts.send(i.encode())
 ts.close()
 return

Admin Client

import ssl
import socket
s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
ts = ssl.wrap_socket(s, certfile="100298750.crt",
 keyfile="100298750.key",
 ca_certs="5cc515-root-ca.cer")
ts.connect(('127.0.0.1', 4001))
ts.send("Hello\r\n".encode())
if ts.recv(80).decode() == "Admin-Greetings\r\n":
 print("The players currently online are:\n")
 ts.send("Who\r\n".encode())
 loop = True
 try:
 while(loop == True): 
 if (ts.recv(1000) != Null):
 print(ts.recv(1000).decode())
 else:
 loop = False
 ts.close() 
 except:
 pass

• Mark Tolonen: "isn't working" isn't descriptive. What is the expected output vs. actual output, including full tracebacks if an exception occurs?

Answer 1

The first problem is that you try to do != Null, which will raise a NameError as Null is not valid in python, it's None. You don't see that error because of the raw except. You should only except the errors you are actually expecting.

In addition to that, recv doesn't return None when there is not data or the connection is closed, it returns an empty string.

Then in your loop you call recv twice, throwing away the result of the first call after the comparison. A better way to write your loop would be:

try:
 data = ts.recv(1000)
 while data:
 print(data.decode())
 data = ts.recv(1000)
except IOError as e:
 pass
finally:
 ts.close()

Or, if you want a more pythonic solution, use a function iterator with the empty string as sentinel:

from functools import partial
for data in iter(partial(ts.recv, 1000), b''):
 print(data.decode())