Mercurial > hg > CAPTCHAmiddleware

annotate captchamiddleware/middleware.py @ 8:59245309f054 default tip

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conform to modern version of lxmlmiddleware
author k0s <k0scist@gmail.com>
date Fri, 26 Feb 2010 15:40:56 -0500
parents ce757057961c
children
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1 """
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2 CAPTCHA middleware
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3 """
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4
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5 import os
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6 import random
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7 import sys
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8 from lxml import etree
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9 from lxmlmiddleware import LXMLMiddleware
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10 from skimpyGimpy import skimpyAPI
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11 from urllib2 import urlopen
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12 from webob import Request, exc
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13
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14
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15 class CAPTCHAmiddleware(LXMLMiddleware):
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16 """
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17 put CAPTCHAs on forms for unauthorized users
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18 """
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19
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20 ### class level variables
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21 defaults = {
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22 'dictionary': '/usr/share/dict/words',
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23 'error': '<span class="error">Please type the CAPTCHA</span>',
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24 'minimum_length': 5,
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25 'path': "/input[@type='submit']",
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26 }
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27
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28 def __init__(self, app, **kw):
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29 self.app = app
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30
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31 # set instance parameters from kw and defaults
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32 for key in self.defaults:
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33 setattr(self, key, kw.get(key, self.defaults[key]))
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34 self.minimum_length = int(self.minimum_length)
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35 assert os.path.exists(self.dictionary)
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36
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37 # get dictionary
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38 if self.dictionary.startswith('http://') or self.dictionary.startswith('https://'):
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39 f = urlopen(self.dictionary)
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40 else:
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41 f = file(self.dictionary)
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42
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43 # characters skimpygimpy doesnt know about
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44 forbidden_characters = set(["'"])
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45
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46 self.words = [ i.strip().lower() for i in f.readlines()
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47 if (len(i.strip()) > self.minimum_length)
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48 and not forbidden_characters.intersection(i) ]
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49 random.shuffle(self.words)
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50
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51 def check_captcha(self, request):
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52 captcha = request.POST.get('captcha', '').lower()
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53 key = request.POST.get('key')
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54 if not key: return False
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55 try:
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56 key = int(key)
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57 except ValueError:
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58 return False
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59 try:
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60 value = self.words[key]
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61 except IndexError:
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62 raise # TODO: better error handling
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63 return value == captcha
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64
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65 def __call__(self, environ, start_response):
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66 request = Request(environ)
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67 if request.method == 'POST' and not request.remote_user:
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68 if not self.check_captcha(request):
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69 location = request.referrer
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70 return exc.HTTPSeeOther(location=location)(environ, start_response)
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71 # TODO: set a cookie to record an error
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72 # stage 2: record form values from request.POST,
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73 # and reinsert them into the form so that users
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74 # don't hate me ;)
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75
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76 return LXMLMiddleware.__call__(self, environ, start_response)
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77
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78 def manipulate(self, request, response, tree):
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79 """manipulate the DOM; should return an etree._Element"""
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80
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81 # don't use CAPTCHAs for authorized users
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82 if request.remote_user:
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83 return tree
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84
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85 for element in tree.findall(".//form[@method='post']"):
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86 key = random.Random().randint(0, len(self.words))
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87 word = self.words[key]
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88 captcha = skimpyAPI.Pre(word).data()
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89 string = '<div class="captcha">%s<input type="hidden" name="key" value="%s"/><input type="text" name="captcha"/></div>' % (captcha, key)
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90 addition = etree.fromstring(string)
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91 insertion_point = element.find('.' + self.path)
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92 insertion_point.addprevious(addition)
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93
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94 return tree
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95