142 lines
4.7 KiB
Python
142 lines
4.7 KiB
Python
# Zope Captcha generation
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import os.path
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import random
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import re
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import sha
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import string
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import sys
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import time
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from skimpyGimpy import skimpyAPI
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from zope.interface import implements
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from zope.component import getUtility
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from Acquisition import aq_inner
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from App.config import getConfiguration
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from Globals import package_home
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from Products.Five import BrowserView
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from plone.keyring.interfaces import IKeyManager
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from interfaces import ICaptchaView
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CHARS = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789'
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# note: no 0/o/O and i/I/1 confusion
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COOKIE_ID = 'captchasessionid'
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WORDLENGTH = 7
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_package_home = package_home(globals())
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WAVSOUNDS = os.path.join(_package_home, 'waveIndex.zip')
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VERAMONO = os.path.join(_package_home, 'arevmoit.bdf')
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_TEST_TIME = None
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class Captcha(BrowserView):
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implements(ICaptchaView)
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_session_id = None
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__name__ = 'captcha'
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def _setcookie(self, id):
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"""Set the session cookie"""
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resp = self.request.response
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if COOKIE_ID in resp.cookies:
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# clear the cookie first, clearing out any expiration cookie
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# that may have been set during verification
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del resp.cookies[COOKIE_ID]
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resp.setCookie(COOKIE_ID, id, path='/')
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def _generate_session(self):
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"""Create a new session id"""
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if self._session_id is None:
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id = sha.new(str(random.randrange(sys.maxint))).hexdigest()
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self._session_id = id
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self._setcookie(id)
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def _verify_session(self):
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"""Ensure session id and cookie exist"""
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if not self.request.has_key(COOKIE_ID):
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if self._session_id is None:
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# This may happen e.g. when the user clicks the back button
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self._generate_session()
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else:
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# This may happen e.g. when the user does not accept the cookie
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self._setcookie(self._session_id)
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# Put the cookie value into the request for immediate consumption
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self.request.cookies[COOKIE_ID] = self._session_id
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def _generate_words(self):
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"""Create words for the current session
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We generate one for the current 5 minutes, plus one for the previous
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5. This way captcha sessions have a livespan of 10 minutes at most.
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"""
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session = self.request[COOKIE_ID]
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nowish = _TEST_TIME or int(time.time() / 300)
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# The line above defines nowish, which tells us what five minutes slot
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# we're in. Indeed, every second, int(time.time()) increments by 1, so
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# int(time.time() / 300) will increment by 1 every 5 minutes.
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secret = getUtility(IKeyManager).secret()
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seeds = [sha.new(secret + session + str(nowish)).digest(),
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sha.new(secret + session + str(nowish - 1)).digest()]
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# The line above generates a seed based on the "nowish" of 5 minutes ago.
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words = []
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for seed in seeds:
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word = []
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for i in range(WORDLENGTH):
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index = ord(seed[i]) % len(CHARS)
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word.append(CHARS[index])
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words.append(''.join(word))
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return words
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def _url(self, type):
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return '%s/@@%s/%s' % (
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aq_inner(self.context).absolute_url(), self.__name__, type)
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def image_tag(self):
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self._generate_session()
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return '<img src="%s" />' % (self._url('image'),)
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def audio_url(self):
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self._generate_session()
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return self._url('audio')
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def verify(self, input):
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if not input:
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return False
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result = False
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try:
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for word in self._generate_words():
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result = result or input.upper() == word.upper()
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# Delete the session key, we are done with this captcha
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self.request.response.expireCookie(COOKIE_ID, path='/')
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except KeyError:
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pass # No cookie
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return result
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# Binary data subpages
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def _setheaders(self, type):
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resp = self.request.response
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resp.setHeader('content-type', type)
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# no caching please
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resp.setHeader('cache-control', 'no-cache, no-store')
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resp.setHeader('pragma', 'no-cache')
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resp.setHeader('expires', 'now')
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def image(self):
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"""Generate a captcha image"""
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self._verify_session()
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self._setheaders('image/png')
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return skimpyAPI.Png(self._generate_words()[0],
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fontpath=VERAMONO).data()
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def audio(self):
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"""Generate a captcha audio file"""
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self._verify_session()
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self._setheaders('audio/wav')
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return skimpyAPI.Wave(self._generate_words()[0], WAVSOUNDS).data()
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