Recipe14.10.Finding an Internet Explorer Cookie

Recipe 14.10. Finding an Internet Explorer Cookie

Credit: Andy McKay

Problem

You need to find a specific IE cookie.

Solution

Cookies that your browser has downloaded contain potentially useful information, so it's important to know how to get at them. With Internet Explorer (IE), one simple approach is to access the registry to find where the cookies are, then read them as files. Here is a module with the function you need for that purpose:

import re, os, glob import win32api, win32con def _getLocation( ):     """ Examines the registry to find the cookie folder IE uses """     key = r'Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders'     regkey = win32api.RegOpenKey(win32con.HKEY_CURRENT_USER, key, 0,         win32con.KEY_ALL_ACCESS)     num = win32api.RegQueryInfoKey(regkey)[1]     for x in range(num):         k = win32api.RegEnumValue(regkey, x)         if k[0] == 'Cookies':             return k[1] def _getCookieFiles(location, name):     """ Rummages through cookie folder, returns filenames including `name'.     `name' is normally the domain, e.g 'activestate' to get cookies for     activestate.com (also e.g. for activestate.foo.com, but you can     filter out such accidental hits later). """     filemask = os.path.join(location, '*%s*' % name)     return glob.glob(filemask) def _findCookie(filenames, cookie_re):     """ Look through a group of files for a cookie that satisfies a     given compiled RE, returning first such cookie found, or None. """     for file in filenames:         data = open(file, 'r').read( )         m = cookie_re.search(data)         if m: return m.group(1) def findIECookie(domain, cookie):     """ Finds the cookie for a given domain from IE cookie files """     try:         l = _getLocation( )     except Exception, err:         # Print a debug message         print "Error pulling registry key:", err         return None     # Found the key; now find the files and look through them     f = _getCookieFiles(l, domain)     if f:         cookie_re = re.compile('%s\n(.*?)\n' % cookie)         return _findCookie(f, cookie_re)     else:         print "No cookies for domain (%s) found" % domain         return None if _ _name_ _=='_ _main_ _':     print findIECookie(domain='kuro5hin', cookie='k5-new_session')

Discussion

While Netscape cookies are in a text file, IE keeps cookies as files in a directory, and you need to access the registry to find which directory that is. To access the Windows registry, this recipe uses the PyWin32 Windows-specific Python extensions; as an alternative, you could use the _winreg module that is part of Python's standard distribution for Windows. This recipe's code has been tested and works on IE 5 and 6.

In the recipe, the _getLocation function accesses the registry and finds and returns the directory that IE is using for cookie files. The _getCookieFiles function receives the directory as an argument and uses standard module glob to return all filenames in the directory whose names include a particular requested domain name. The _findCookie function opens and reads all such files in turn, until it finds one whose contents satisfy a compiled regular expression that the function receives as an argument. It then returns the substring of the file's contents corresponding to the first parenthesized group in the regular expression, or None when no satisfactory file is found. As the leading underscore in the names indicates, these are all internal functions, used only as implementation details of the only function this module is meant to expose, namely findIECookie, which uses the other functions to locate and return the value of a specific cookie for a given domain.

An alternative to this recipe would be to write a Python extension, or use calldll or ctypes, to access the InternetGetCookie API function in Wininet.DLL, as documented on MSDN (Microsoft Developer Network).

Recipe14.10.Finding an Internet Explorer Cookie