Creating proxy pac files automatically from Squid Conf file.

Pac files are automatic proxy configuration files written in js format that browsers can interpret and route clients to the proxy according to the domain name they visit. This pac file should be published through a web server or can be manually downloaded and the browser should be configured to the downloaded pac file. Squid is an open source proxy server which can be configured to be used by libraries for out off campus access to the academic database subscriptions . When someone add/delete/update an entry in the squid conf file, pac files should also be updated properly. This is a tedious task for large numbers of urls. Python script which automates this task with per minute cron entry

The script pushes syslogs to the syslog of the system on every execution. If any changes made to the squid file, the pac file is updated by checking the hash of the old and new states of the file. Also the squid proceess is restarted if any change has been made.

import hashlib
import os
import syslog
import datetime
import shutil
import subprocess
squid_config_file_path="/etc/squid/kutuphane_veritabanlari.squid"
squid_config_file = open(squid_config_file_path)
readFile = squid_config_file.read()
pac_file_root="/var/www/html"
hash_file="%s/hash_file"%pac_file_root
old_pac_file="%s/proxy.pac"%pac_file_root
date_=datetime.datetime.now() 
backup_file="%s/pac_backup_file_%s.pac"%(pac_file_root,date_)
new_pac_filee="%s/new_pac_file.pac"%pac_file_root
sha1Hash = hashlib.sha1(readFile)
sha1Hashed = sha1Hash.hexdigest()
if os.path.exists(hash_file):
   hash_filee = open(hash_file,'r')
   readHash = hash_filee.readline()
   hash_filee.close()
   if not readHash==sha1Hashed:
 syslog.syslog(syslog.LOG_WARNING,"Hashes are different  kutuphane_veritabanlari.squid config file has been modified the old hash :%s new hash:%s "%(readHash,sha1Hashed))
 shutil.copyfile(old_pac_file,backup_file) 
 new_pac_file = open(new_pac_filee,"w+")
    new_pac_file.write("function FindProxyForURL(url, host) {\n")
 new_pac_file.write("var proxyserver = 'proxy2.iyte.edu.tr:8080';\n")    
 new_pac_file.write("var proxylist = new Array(\n")
    with open(squid_config_file_path) as openfileobject:
           for line in openfileobject:
          if (line[0].isalpha() or line.startswith(".")):
   new_pac_file.write('"%s",\n' % (line.rstrip()))
        new_pac_file.write('"dummy.com"\n);\n')
    new_pac_file.write("for(var i=0; i<proxylist.length; i++) {\n")
    new_pac_file.write("\tvar value = proxylist[i];\n")
    new_pac_file.write("\t\tif (dnsDomainIs(host, value) ) {\n")
    new_pac_file.write("\t\treturn 'PROXY '+proxyserver;\n")
    new_pac_file.write("\t}\n")
    new_pac_file.write("}\n")
    new_pac_file.write("return 'DIRECT';\n")
    new_pac_file.write("}")
 new_pac_file.close()
 os.remove(hash_file) 
 hash_file_create=open(hash_file,'w')
     hash_file_create.write(sha1Hashed)
     hash_file_create.close() 
 shutil.copyfile(new_pac_filee,old_pac_file)
 subprocess.call("%s %s %s" % ('service', 'squid', 'reload'),shell=True)
   else:
 syslog.syslog(syslog.LOG_WARNING,"Hashes are same kutuphane_veritabanlari.squid config file hasn't been changed.")
else:
    hash_file_create=open(hash_file,'w')
    hash_file_create.write(sha1Hashed)
    hash_file_create.close()
squid_config_file.close()