Optional blacklist for word pair generation

diff --git a/captcha.py b/captcha.py
index c9d91056d72a10c2515e900262b34614ad141a30..b2d2a063ca1c7d8945eef7cebf534e3758b67b28 100644 (file)
--- a/captcha.py
+++ b/captcha.py
@@ -114,7 +114,27 @@ def gen_subdir(basedir, hash, levels):
                if not os.path.exists(fulldir):
                        os.mkdir(fulldir)
        return subdir
-       
+
+def try_pick_word(words, blacklist, verbose):
+       word1 = words[random.randint(0,len(words)-1)]
+       word2 = words[random.randint(0,len(words)-1)]
+       word = word1+word2
+       for naughty in blacklist:
+               if naughty in word:
+                       if verbose:
+                               print "skipping word pair '%s' because it contains blacklisted word '%s'" % (word, naughty)
+                       return None
+       return word
+
+def pick_word(words, blacklist, verbose):
+       while True:
+               word = try_pick_word(words, blacklist, verbose)
+               if word:
+                       return word
+
+def read_wordlist(filename):
+       return [string.lower(x.strip()) for x in open(wordlist).readlines()]
+
 if __name__ == '__main__':
        """This grabs random words from the dictionary 'words' (one
        word per line) and generates a captcha image for each one,
@@ -125,6 +145,7 @@ if __name__ == '__main__':
        """
        font = "VeraBd.ttf"
        wordlist = "awordlist.txt"
+       blacklistfile = None
        key = "CHANGE_THIS_SECRET!"
        output = "."
        count = 20
@@ -132,12 +153,14 @@ if __name__ == '__main__':
        dirs = 0
        verbose = False
        
-       opts, args = getopt.getopt(sys.argv[1:], "", ["font=", "wordlist=", "key=", "output=", "count=", "fill=", "dirs=", "verbose"])
+       opts, args = getopt.getopt(sys.argv[1:], "", ["font=", "wordlist=", "blacklist=", "key=", "output=", "count=", "fill=", "dirs=", "verbose"])
        for o, a in opts:
                if o == "--font":
                        font = a
                if o == "--wordlist":
                        wordlist = a
+               if o == "--blacklist":
+                       blacklistfile = a
                if o == "--key":
                        key = a
                if o == "--output":
@@ -156,15 +179,19 @@ if __name__ == '__main__':
                # files after...
                count = max(0, fill - len(os.listdir(output)))
        
-       words = [string.lower(x.strip()) for x in open(wordlist).readlines()]
+       words = read_wordlist(wordlist)
        words = [x for x in words
                if len(x) <= 5 and len(x) >= 4 and x[0] != "f"
                and x[0] != x[1] and x[-1] != x[-2]
                and (not "'" in x)]
+       
+       if blacklistfile:
+               blacklist = read_wordlist(blacklistfile)
+       else:
+               blacklist = []
+       
        for i in range(count):
-               word1 = words[random.randint(0,len(words)-1)]
-               word2 = words[random.randint(0,len(words)-1)]
-               word = word1+word2
+               word = pick_word(words, blacklist, verbose)
                salt = "%08x" % random.randrange(2**32)
                # 64 bits of hash is plenty for this purpose
                hash = md5.new(key+salt+word+key+salt).hexdigest()[:16]