Python Web服务器-拆分文件名时出现IndexError

Question

I have successfully been able to access my web-server from a browser, downloaded a file on the server and properly viewed it with chrome. However, when the server standbys for approx. 20 seconds, it'll crash with an IndexError.

from socket import *
serverport = 972
serverSocket = socket(AF_INET, SOCK_STREAM)
serverSocket.bind(('', serverport))
serverSocket.listen(1)
print 'Standing by...'

while True:
    #Establish the connection
    connectionSocket, addr = serverSocket.accept()

    try:
        message = connectionSocket.recv(1024)
        filename = message.split()[1]
        f = open(filename[1:])
        outputdata = f.read()

        for i in range(0, len(outputdata)):
            connectionSocket.send(outputdata[i])
        print 'Success! File sent!'
        connectionSocket.close()

    except IOError:
        errormessage = 'Error 404 - File not found'
        connectionSocket.send(errormessage)

The output i get is the following:

Standing by..
Success! File sent! #sent everytime i request the webpage on the client localhost:80/helloworld.html
Traceback (most recent call last):
  File "C:/Users/Nikolai/Dropbox/NTNU/KTN/WebServer/TCPServer.py", line 14, in <module>
    filename = message.split()[1]
IndexError: list index out of range

Answer 1

This is probably the client closing the connection. When the connection is finished, an empty string '' is received.

''.split()[1] will fail with index out of range . My advice is to try with this patch:

message = connectionSocket.recv(1024)
if not message:
    # do something like return o continue

As an aside, you should recv from your socket until you get the empty string. In your code, what happens if the request is larger than 1024 ? Something like this can be done:

try:
    message = ''
    rec = connectionSocket.recv(1024)
    while rec:
        rec = connectionSocket.recv(1024)
        message += rec
    if not message:
        connectionSocket.close()            
        continue
    filename = message.split()[1]
    f = open(filename[1:])
    outputdata = f.read()

    for i in range(0, len(outputdata)):
        connectionSocket.send(outputdata[i])
    print 'Success! File sent!'
    connectionSocket.close()

You should read Socket Programming HOWTO , specially the part of creating multithreaded servers, which is probably how you want to do yours :)

Hope this helps!