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1 # copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved. |
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2 # contact http://www.logilab.fr/ -- mailto:contact@logilab.fr |
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3 # |
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4 # This file is part of CubicWeb. |
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5 # |
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6 # CubicWeb is free software: you can redistribute it and/or modify it under the |
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7 # terms of the GNU Lesser General Public License as published by the Free |
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8 # Software Foundation, either version 2.1 of the License, or (at your option) |
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9 # any later version. |
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10 # |
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11 # CubicWeb is distributed in the hope that it will be useful, but WITHOUT |
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12 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS |
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13 # FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more |
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14 # details. |
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15 # |
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16 # You should have received a copy of the GNU Lesser General Public License along |
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17 # with CubicWeb. If not, see <http://www.gnu.org/licenses/>. |
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18 """Simple captcha library, based on PIL. Monkey patch functions in this module |
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19 if you want something better... |
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20 """ |
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21 |
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22 __docformat__ = "restructuredtext en" |
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23 |
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24 from random import randint, choice |
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25 from io import BytesIO |
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26 |
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27 from six.moves import range |
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28 |
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29 from PIL import Image, ImageFont, ImageDraw, ImageFilter |
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30 |
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31 |
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32 from time import time |
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33 |
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34 from cubicweb import tags |
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35 from cubicweb.web import ProcessFormError, formwidgets as fw |
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36 |
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37 |
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38 def pil_captcha(text, fontfile, fontsize): |
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39 """Generate a captcha image. Return a PIL image object. |
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40 |
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41 adapted from http://code.activestate.com/recipes/440588/ |
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42 """ |
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43 # randomly select the foreground color |
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44 fgcolor = randint(0, 0xffff00) |
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45 # make the background color the opposite of fgcolor |
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46 bgcolor = fgcolor ^ 0xffffff |
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47 # create a font object |
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48 font = ImageFont.truetype(fontfile, fontsize) |
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49 # determine dimensions of the text |
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50 dim = font.getsize(text) |
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51 # create a new image slightly larger that the text |
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52 img = Image.new('RGB', (dim[0]+5, dim[1]+5), bgcolor) |
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53 draw = ImageDraw.Draw(img) |
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54 # draw 100 random colored boxes on the background |
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55 x, y = img.size |
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56 for num in range(100): |
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57 draw.rectangle((randint(0, x), randint(0, y), |
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58 randint(0, x), randint(0, y)), |
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59 fill=randint(0, 0xffffff)) |
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60 # add the text to the image |
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61 draw.text((3, 3), text, font=font, fill=fgcolor) |
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62 img = img.filter(ImageFilter.EDGE_ENHANCE_MORE) |
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63 return img |
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64 |
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65 |
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66 def captcha(fontfile, fontsize, size=5, format='JPEG'): |
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67 """Generate an arbitrary text, return it together with a buffer containing |
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68 the captcha image for the text |
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69 """ |
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70 text = u''.join(choice('QWERTYUOPASDFGHJKLZXCVBNM') for i in range(size)) |
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71 img = pil_captcha(text, fontfile, fontsize) |
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72 out = BytesIO() |
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73 img.save(out, format) |
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74 out.seek(0) |
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75 return text, out |
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76 |
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77 |
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78 class CaptchaWidget(fw.TextInput): |
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79 def render(self, form, field, renderer=None): |
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80 # t=int(time()*100) to make sure img is not cached |
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81 src = form._cw.build_url('view', vid='captcha', t=int(time()*100), |
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82 captchakey=field.input_name(form)) |
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83 img = tags.img(src=src, alt=u'captcha') |
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84 img = u'<div class="captcha">%s</div>' % img |
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85 return img + super(CaptchaWidget, self).render(form, field, renderer) |
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86 |
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87 def process_field_data(self, form, field): |
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88 captcha = form._cw.session.data.pop(field.input_name(form), None) |
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89 val = super(CaptchaWidget, self).process_field_data(form, field) |
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90 if val is None: |
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91 return val # required will be checked by field |
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92 if captcha is None: |
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93 msg = form._cw._('unable to check captcha, please try again') |
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94 raise ProcessFormError(msg) |
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95 elif val.lower() != captcha.lower(): |
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96 msg = form._cw._('incorrect captcha value') |
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97 raise ProcessFormError(msg) |
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98 return val |