A Glimpse of GNU/Linux

This is a minimalist implementation of a working gopher server in Python programming language. It is buggy but it works

#!/usr/bin/env python

# gopherd.py – A Simple Gopher Server
# By Maxin B. John (maxinbjohn@gmail.com)
#
# This little program illustrates the gopher protocol implementation
# using python with the help of SocketServer module.
#
# The gopher protocol is a very simple TCP-based protocol;which listen
# on port number 70.The Internet Gopher protocol is designed for
# distributed document search and retrieval.
#
# The Internet Gopher protocol is designed primarily to act as a
# distributed document delivery system.  While documents (and services)
# reside on many servers, Gopher client software presents users with a
# hierarchy of items and directories much like a file system. 

import SocketServer
import string
import os

class GopherHandler(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.
        searchstring=self.rfile.readline(512)
        print ‘searching ‘+ searchstring
    # Remove any leading and trailing whitespace, including the
        # trailing newline.
        searchstring=string.strip(searchstring)
    # invoking the get_directory_info to get the return string
    info = self.get_directory_info(searchstring)
    # send the data back to gopher client
        self.wfile.write(info)
    print ‘printing the info \n’+ info
    # The following method takes a string containing the searchstring
    # This function will search the directory and provide the information
    # in Gopher Protocol format. Later will be expanded to contain the searching
    # logic based on the searchstring.

    def get_directory_info(self, searchstring):
    info = ”
    dir_path=os.getcwd()
       
    #Testing whether the request is for a particular file or folder
    #if (searchstring == “” or os.path.isdir(searchstring)== 1):
    if (searchstring == “”):
        “Return a string containing the file and directory information in gopher protocol format.”
        file_list= os.listdir(os.getcwd())
        for fileName in file_list:
            if os.path.isfile(fileName) == 1:
                info += ’0′+fileName+’\t’+fileName+’\tlocalhost\t70\r\n’
            elif os.path.isdir(fileName) == 1:
                info += ’1′+fileName+’\t’+fileName+’\tlocalhost\t70\r\n’
            else:
                print ‘This is a link ‘ +fileName
                info += ’2′+fileName+’\t’+fileName+’\tlocalhost\t70\r\n’
        return “%s\r\n” % (info,)
    else:
        fileName = searchstring
        if os.path.isfile(fileName) == 1:
            info = self.handle_file(fileName)

        elif os.path.isdir(fileName) == 1:
            info = self.handle_folder(fileName)
        else:
            info = ‘nothing’
        return “%s\r\n” % (info,)

    # Function to handle the request for a file
    def handle_file(self, fileName):
    fd = open(fileName,’r')
    textcontent = fd.read()+’\r\n’   
    return “%s \r\n” %(textcontent,)        
   
    # Function to handle the request for a folder
    def handle_folder(self, files):
    info = ”
    os.chdir(os.getcwd()+’/'+files)
    file_list= os.listdir(os.getcwd())
    for fileName in file_list:
            if os.path.isfile(fileName) == 1:
                info += ’0′+fileName+’\t’+fileName+’\tlocalhost\t70\r\n’
            elif os.path.isdir(fileName) == 1:
                info += ’1′+fileName+’\t’+fileName+’\tlocalhost\t70\r\n’
            else:
                print ‘This is a link ‘ +fileName
                info += ’2′+fileName+’\t’+fileName+’\tlocalhost\t70\r\n’
    return “%s\r\n” % (info,)
       
# If this script is being run directly, it’ll start acting as a gopher
# daemon. The following “if” statement is the usual Python style for
# running code only as a stand alone script.

if __name__==’__main__’:

    try:
        # Create an instance of our server class
        server=SocketServer.ForkingTCPServer( (”, 70), GopherHandler)
        # Enter an infinite loop, waiting for requests and then servicing them.
        server.serve_forever()

    # For graceful exit when ^c is used. 
    except KeyboardInterrupt:
    print “Received Keyboard interrput: Exiting…”
    exit

For me, Networking was one of the toughest subject that I have ever touched. I kept myself away from that for a long time just because of the ‘initial lag’ of learning and programming in a “New World”.
  But later , I found that using Python , it can be made simple. So I went on experimenting in it.  Lots of people were telling that the protocol implementation is one of the toughest regions in Networking.
So I decided to give it a try, by implementing a good old Gopher server (Grand father of google ) .. Gopher protocol is defined in the RFC 1436. It is a TCP based protocol listening on port 70. So using these , I have decided to give it a try ..  Got a half baked gopher …It is under construction , but being a believer of the the Free Software Philosophy, I am Publishing it (even if it is not complete )..

#!/usr/bin/env python

# gopherd.py – A Simple Gopher Server
# By Maxin B. John (maxinbjohn@gmail.com)
#
# This little program illustrates the gopher protocol implementation
# using python with the help of SocketServer module.
#
# The gopher protocol is a very simple TCP-based protocol;which listen
# on port number 70.The Internet Gopher protocol is designed for
# distributed document search and retrieval.
#
# The Internet Gopher protocol is designed primarily to act as a
# distributed document delivery system.  While documents (and services)
# reside on many servers, Gopher client software presents users with a
# hierarchy of items and directories much like a file system. 

import SocketServer
import string

class GopherHandler(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.
        searchstring=self.rfile.readline(512)
        print ‘searching ‘+ searchstring
        # Remove any leading and trailing whitespace, including the
        # trailing newline.
        searchstring=string.strip(searchstring)
    # invoking the get_directory_info to get the return string
    info = self.get_directory_info(searchstring)
    # send the data back to gopher client
        self.wfile.write(info)
    print info

    # The following method takes a string containing the searchstring
    # This function will search the directory and provide the information
    # in Gopher Protocol format. Later will be expanded to contain the searching
    # logic based on the searchstring.

    def get_directory_info(self, searchstring):
        “Return a string containing the file and directory information in gopher protocol format.”
    info=”0Sorry, but the requested token could not be found\tErr\tlocalhost\t70\r\n.\r\n\r\n”
        return “%s\r\n” % (info,)

# If this script is being run directly, it’ll start acting as a gopher
# daemon. The following “if” statement is the usual Python style for
# running code only as a stand alone script.

if __name__==’__main__’:

    try:
        # Create an instance of our server class
        server=SocketServer.ForkingTCPServer( (”, 70), GopherHandler)
        # Enter an infinite loop, waiting for requests and then servicing them.
        server.serve_forever()

    # For graceful exit when ^c is used. 
    except KeyboardInterrupt:
    print “Received Keyboard interrput: Exiting…”
    exit

#############################
Though this is far from completion, it will show the gopher’s output
Run the program

python gopherd.py

Then just type
gopher://localhost in your favourite firefox browser, you will see the output of a “Gopher Server”. But I don’t know whether the gopher support is present in IE. But who cares