Simplify captcha configuration

We provide some built-in captcha classes, and the user can select them
with a simple string. He/she can still use a custom class.

At the moment, only the title captcha is supported.

Signed-off-by: Alberto Bertogli <albertito@blitiri.com.ar>

diff --git a/blitiri.cgi b/blitiri.cgi
index 5b0b27e532357c90a4b39e8c7ae840c4b6430375..8c6c6dc251e3d22c373352f609794bbac289b31f 100755 (executable)
--- a/blitiri.cgi
+++ b/blitiri.cgi
@@ -46,32 +46,10 @@ author = "Hartmut Kegan"
 # Article encoding
 encoding = "utf8"
 
-# Captcha class
-class Captcha (object):
-       def __init__(self, article):
-               self.article = article
-               words = article.title.split()
-               self.nword = hash(article.title) % len(words) % 5
-               self.answer = words[self.nword]
-               self.help = 'gotcha, damn spam bot!'
-
-       @property
-       def puzzle(self):
-               nword = self.nword + 1
-               if nword == 1:
-                       n = '1st'
-               elif nword == 2:
-                       n = '2nd'
-               elif nword == 3:
-                       n = '3rd'
-               else:
-                       n = str(nword) + 'th'
-               return "enter the %s word of the article's title" % n
-
-       def validate(self, form_data):
-               if form_data.captcha.lower() == self.answer.lower():
-                       return True
-               return False
+# Captcha method to use. At the moment only "title" is supported, but if you
+# are keen with Python you can provide your own captcha implementation, see
+# below for details.
+captcha_method = "title"
 
 
 #
@@ -107,6 +85,84 @@ except:
 data_path = os.path.realpath(data_path)
 templates_path = os.path.realpath(templates_path)
 
+
+#
+# Captcha classes
+#
+# They must follow the interface described below.
+#
+# Constructor:
+#      Captcha(article) -> constructor, takes an article[1] as argument
+# Attributes:
+#      puzzle -> a string with the puzzle the user must solve to prove he is
+#                not a bot (can be raw HTML)
+#      help -> a string with extra instructions, shown only when the user
+#              failed to solve the puzzle
+# Methods:
+#      validate(form_data) -> based on the form data[2],  returns True if
+#                             the user has solved the puzzle uccessfully
+#                             (False otherwise).
+#
+# Note you must ensure that the puzzle attribute and validate() method can
+# "communicate" because they are executed in different requests. You can pass a
+# cookie or just calculate the answer based on the article's data, for example.
+#
+# [1] article is an object with all the article's information:
+#      path -> string
+#      created -> datetime
+#      updated -> datetime
+#      uuid -> string (unique ID)
+#      title -> string
+#      author -> string
+#      tags -> list of strings
+#      raw_contents -> string in rst format
+#      comments -> list of Comment objects (not too relevant here)
+# [2] form_data is an object with the form fields (all strings):
+#      author, author_error
+#      link, link_error
+#      catpcha, captcha_error
+#      body, body_error
+#      action, method
+
+class TitleCaptcha (object):
+       "Captcha that uses the article's title for the puzzle"
+       def __init__(self, article):
+               self.article = article
+               words = article.title.split()
+               self.nword = hash(article.title) % len(words) % 5
+               self.answer = words[self.nword]
+               self.help = 'gotcha, damn spam bot!'
+
+       @property
+       def puzzle(self):
+               nword = self.nword + 1
+               if nword == 1:
+                       n = '1st'
+               elif nword == 2:
+                       n = '2nd'
+               elif nword == 3:
+                       n = '3rd'
+               else:
+                       n = str(nword) + 'th'
+               return "enter the %s word of the article's title" % n
+
+       def validate(self, form_data):
+               if form_data.captcha.lower() == self.answer.lower():
+                       return True
+               return False
+
+known_captcha_methods = {
+       'title': TitleCaptcha,
+}
+
+# If the configured captcha method was a known string, replace it by the
+# matching class; otherwise assume it's already a class and leave it
+# alone. This way the user can either use one of our methods, or provide one
+# of his/her own.
+if captcha_method in known_captcha_methods:
+       captcha_method = known_captcha_methods[captcha_method]
+
+
 # Default template
 
 default_main_header = """\
@@ -986,7 +1042,7 @@ def render_comments(article, template, form_data):
        if not form_data:
                form_data = CommentFormData()
        form_data.action = blog_url + '/comment/' + article.uuid + '#comment'
-       captcha = Captcha(article)
+       captcha = captcha_method(article)
        print template.get_comment_form(article, form_data, captcha.puzzle)
 
 def render_html(articles, db, actyear = None, show_comments = False,
@@ -1156,7 +1212,7 @@ def handle_cgi():
                                link.strip().replace('\n', ' '), captcha,
                                body.replace('\r', ''))
                article = db.get_article(uuid)
-               captcha = Captcha(article)
+               captcha = captcha_method(article)
                redirect = False
                valid = True
                if not form_data.author:

diff --git a/config.py.sample b/config.py.sample
index eda5a47df4ea49190a3f970471b312e60272d055..1b9d0776fef8a06fe23ddd5093c102b2cb8642a0 100644 (file)
--- a/config.py.sample
+++ b/config.py.sample
@@ -42,47 +42,8 @@ author = "Hartmut Kegan"
 # Article encoding
 encoding = "utf8"
 
-# You can customize the captcha engine by providing a Captcha class with this
-# interface:
-# Constructor:
-#      Captcha(article) -> constructor, takes an article[1] as argument
-# Attributes:
-#      puzzle -> a string with the puzzle the user must solve to prove he is
-#                not a bot (can be raw HTML)
-#      help -> a string with extra instructions, shown only when the user
-#              failed to solve the puzzle
-# Methods:
-#      validate(form_data) -> based on the form data[2],  returns True if
-#                             the user has solved the puzzle uccessfully
-#                             (False otherwise).
-#
-# Note you must ensure that the puzzle attribute and validate() method can
-# "communicate" because they are executed in different requests. You can pass a
-# cookie or just calculate the answer based on the article's data, for example.
-#
-# Example: a captcha class to completely disable the captcha feature
-# class Captcha (object):
-#      def __init__(self, article):
-#              self.puzzle = ''
-#              self.help = ''
-#      def validate(form_data):
-#              return True
-# Remove the captcha input field from the form template, and that's it!
-#
-# [1] article is an object with all the article's information:
-#      path -> string
-#      created -> datetime
-#      updated -> datetime
-#      uuid -> string (unique ID)
-#      title -> string
-#      author -> string
-#      tags -> list of strings
-#      raw_contents -> string in rst format
-#      comments -> list of Comment objects (not too relevant here)
-# [2] form_data is an object with the form fields (all strings):
-#      author, author_error
-#      link, link_error
-#      catpcha, captcha_error
-#      body, body_error
-#      action, method
+# Captcha method to use. At the moment only "title" is supported, but if you
+# are keen with Python you can provide your own implementation, see
+# blitiri.cgi for details.
+captcha_method = "title"