Download cookie-protected pages with Python using cookielib (Part 2)

Warning! In this post I use the Project Euler site as an example. However, it seems that this method doesn’t work anymore with that site. The PE site was updated recently and they have changed something. However, the method described below might work well with other sites.

Update (20111108): If you want to scrape the Project Euler site, check out Part 3 of this series.

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In Part 1 we showed how to download a cookie-protected page with Python + wget. First, cookies of a given site were extracted from Firefox’s cookies.sqlite file and they were stored in a plain-text file called cookies.txt. Then this cookies.txt file was passed to wget and wget fetched the protected page.

The solution above works but it has some drawbacks. First, an external command (wget) is called to fetch the webpage. Second, the extracted cookies must be written in a file for wget.

In this post, we provide a clean, full-Python solution. The extracted cookies are not stored in the file system and the pages are downloaded with a Python module from the standard library.

Step 1: extracting cookies and storing them in a cookiejar
On the blog of Guy Rutenberg I found a post that explains this step. Here is my slightly refactored version:

#!/usr/bin/env python

import os
import sqlite3
import cookielib
import urllib2

COOKIE_DB = "{home}/.mozilla/firefox/cookies.sqlite".format(home=os.path.expanduser('~'))
CONTENTS = "host, path, isSecure, expiry, name, value"
COOKIEFILE = 'cookies.lwp'          # the path and filename that you want to use to save your cookies in
URL = 'http://projecteuler.net/index.php?section=statistics'

def get_cookies(host):
    cj = cookielib.LWPCookieJar()       # This is a subclass of FileCookieJar that has useful load and save methods
    con = sqlite3.connect(COOKIE_DB)
    cur = con.cursor()
    sql = "SELECT {c} FROM moz_cookies WHERE host LIKE '%{h}%'".format(c=CONTENTS, h=host)
    cur.execute(sql)
    for item in cur.fetchall():
        c = cookielib.Cookie(0, item[4], item[5],
            None, False,
            item[0], item[0].startswith('.'), item[0].startswith('.'),
            item[1], False,
            item[2],
            item[3], item[3]=="",
            None, None, {})
        cj.set_cookie(c)

    return cj

def main():
    host = 'projecteuler'
    cj = get_cookies(host)
    for index, cookie in enumerate(cj):
        print index,':',cookie
    #cj.save(COOKIEFILE)    # save the cookies if you want (not necessary)

if __name__=="__main__":
    main()

Step 2: download the protected page using the previously filled cookiejar
Now we need to download the protected page:

def get_page_with_cookies(cj):
    opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cj))
    urllib2.install_opener(opener)

    theurl = URL    # an example url that sets a cookie, try different urls here and see the cookie collection you can make !
    txdata = None   # if we were making a POST type request, we could encode a dictionary of values here - using urllib.urlencode
    #params = {}
    #txdata = urllib.urlencode(params)
    txheaders =  {'User-agent' : 'Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)'}  # fake a user agent, some websites (like google) don't like automated exploration

    req = urllib2.Request(theurl, txdata, txheaders)    # create a request object
    handle = urllib2.urlopen(req)                       # and open it to return a handle on the url

    return handle.read()

See the full source code here. This code is also part of my jabbapylib library (see the “web” module). For one more example, see this project of mine, where I had to download a cookie-protected page.

Resources used

• Building CookieJar out of Firefox’s cookies.sqlite
• cookielib Example

What’s next
In Part 3 we show how to use Mechanize and Splinter (two programmable browsers) to log in to a password-protected site and get the HTML source of a page.