[Tutor] proxy switcher - was Re: I love python / you guys :)

[Stefan Lesicnik]

On Mon, Nov 16, 2009 at 1:36 PM, bibi midi <bibsmendez at gmail.com> wrote:
>
>
> On Mon, Nov 16, 2009 at 1:58 AM, Stefan Lesicnik <stefan at lsd.co.za> wrote:
>>
>> hi,
>>
>> Although not a question, i just want to tell you guys how awesome you are!
>>
>> I am not a programmer, i can do a bit of bash. I have never officially
>> learnt programming, but numerous times looked at some perl, c, java
>> and never really gotten past the beginning stages of it. That all
>> changed when i picked up python. Although my style and use of python
>> is probably barbaric at best, I really enjoy it when you can make
>> things work. Python was just amazing from a readability / logical
>> point of view. If i can think of something, there is a way to do it in
>> python. After learning the simple data structures it seems i can
>> really do anything i want to.
>
>
> Hi Stefan,
>
> Your message mirrored my current state. There's TONS to learn in linux like
> bash, perl, vim, sed, awk, python, etc. Too much to put in your head and in
> the end makes you half-baked e.g. good at start but fades away in the end.
> Anyway i hope to follow your lead and be one among the guys here
> knowledgeable of the language.
>
> In the same lines of if-you-can-think-of-anything-python-can-do-it i got
> inspired to ask a question for the gurus:
>
> When i use our company's LAN i set my proxy variable by hand in .bashrc.
> There are 4 files to insert proxy variable:
>
> in ~/.bashrc, /root/.bashrc, /etc/wgetrc and /etc/apt/apt.conf.
>
> The last one is actually rename e.g. mv to apt.conf to activate proxy and mv
> to apt.conf.bak to deactivate. The proxy variable is something like this
>
> export http_proxy=http://username:password@proxy:port
> ftp_proxy=$http_proxy
>
> To activate i uncomment them then source .bashrc. To deactivate i put back
> the comment sign. I do it all in vim e.g. vim -o the-3-files-above. For
> apt.conf see rename above. I deactivate because i have another internet
> connection option via 3G usb modem. But thats another story.
>
> I will do this myself in python so please show me the way. Surely this can
> be done.
>

Heys,

I do something similair with apt.conf. Below is an older version of an
app i wrote (the new version i have written integrates into network
manager, so when it detects a certain network, it switches all the
corresponding settings!).

This older version has some functions that you might be interested.
Maybe something below helps you.



#!/usr/bin/python

import sys
import fileinput
import re
import netifaces
import glob
import string

from netaddr import IP, CIDR

networks = {}
networks["home"] = {"ip":"192.168.1.0/24","url":"http://192.168.1.2:3142/"}
#networks["home"] =
{"ip":"192.168.1.0/24","url":"http://ecstacy.lsd.co.za:3142/"}
networks["office"] =
{"ip":"172.30.16.16/20","url":"http://ecstacy.lsd.co.za:3142/"}

#Things to keep in sync
sync=["/etc/apt/sources.list","/etc/apt/sources.list.d/*.list"]
#sync=["/etc/apt/sources.list"]

#Search interfaces for IP and compare against variable list
def netcheck():
	for interface in netifaces.interfaces():
		iface = netifaces.ifaddresses(interface)
		if netifaces.AF_INET in iface:
			networkaddr = '%s/%s' %
(netifaces.ifaddresses(interface)[netifaces.AF_INET][0]['addr'],
netifaces.ifaddresses(interface)[netifaces.AF_INET][0]['netmask'])
			networkaddr = IP(networkaddr).cidr()
			print 'networkaddr: %s' % networkaddr
			for name, values in networks.iteritems():
				network = IP(values['ip']).cidr()
				print 'network: %s' % network
				if networkaddr in network:
					location = networks[name]['url']
					print 'Location \'%s\' found. Setting proxy to \'%s\'' % (name,location)
			
#Function to hash out mirrors based on regex - may be useful for
enabling/disabling src package downloads
#Not currently used
def hash():
    for line in fileinput.input("test.list", inplace=1):
        line = line.strip()
        if re.search('^deb', line):
            print '#%s' % line
        else:
            print line

#Function to check if sync list actually exists (maybe should check
for writable?)
def checksync():
    for file in sync:
        if not glob.glob(file):
            print ("Error: %s does not exist" %file)
            sys.exit(1)

#Function to replace mirror
def replace(location=False):
    for file in sync:
        for line in fileinput.input(glob.glob(file), inplace=1):
            line = line.strip()

            if location:
                if re.search('^deb.*http://(.*):3142/', line):
                    print re.sub('http://(.*):3142/', location, line)
                elif re.search('^deb.*http://', line):
		    print re.sub('http://', location, line)
	        else:
		    print line
            elif re.search('^deb.*http://(.*):3142/', line):
	        print re.sub('http://(.*):3142/', 'http://', line)
	    else:
	        print line
	
checksync()
replace('http://ecstacy.lsd.co.za:3142/')
#replace()