#!/usr/bin/env python# fingerd.py# By A.M. Kuchling (amk@amk.ca)## This little program illustrates how easy it is to write network# servers using the classes in the SocketServer module.## The finger protocol is a very simple TCP-based protocol; the client# sends a single line containing the name of the user whose# information is being requested, followed by a newline.# Information about the user should then be sent over the socket# connection to the client. In this implementation, the server simply# tells you who you've fingered; you'd probably want it to retrieve# information from the user's home directory or a database of some sort.#import SocketServerclass FingerHandler(SocketServer.StreamRequestHandler): def handle(self): # Read a line of text, limiting it to 512 bytes. # This will prevent someone trying to crash the server machine # by sending megabytes of data. username=self.rfile.readline(512) # Remove any leading and trailing whitespace, including the # trailing newline. import string username=string.strip(username) # Call the method to get the user's information, and return it # to the client. The SocketServer classes make self.wfile # available to send data to the client. info = self.find_user_info(username) self.wfile.write(info) # The following method takes a string containing the username, # and returns another string containing whatever information is # desired. You can subclass the FingerHandler class and override # this method with your own to produce customized output. def find_user_info(self, username): "Return a string containing the desired user information." return "You fingered the user %s\n" % (repr(username),)# If this script is being run directly, it'll start acting as a finger# daemon. If someone's importing it in order to subclass# FingerHandler, that shouldn't be done. The following "if" statement# is the usual Python idiom for running code only in a script.if __name__=='__main__': # Create an instance of our server class server=SocketServer.TCPServer( ('', 79), FingerHandler) # Enter an infinite loop, waiting for requests and then servicing them. server.serve_forever()
