Add (customizable) captcha support

diff --git a/blitiri.cgi b/blitiri.cgi
index 19c63ea2e850c829b05fe98e99b09d4c507ef1d9..1ae70ff351bf7dee7432a33492480f5dae3ea763 100755 (executable)
--- a/blitiri.cgi
+++ b/blitiri.cgi
@@ -40,6 +40,34 @@ 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!'
+
+       def get_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
+       puzzle = property(fget = get_puzzle)
+
+       def validate(self, form_data):
+               if form_data.captcha.lower() == self.answer.lower():
+                       return True
+               return False
+
+
 #
 # End of configuration
 # DO *NOT* EDIT ANYTHING PAST HERE
@@ -175,6 +203,12 @@ default_comment_form = """
     or <span class="formurlexample">mailto:you@example.com</span>
   </div>
 </div>
+<div class="comformcaptcha">
+  <label for="comformcaptcha">Your humanity proof %(form_captcha_error)s</label>
+  <input type="text" class="comformcaptcha" id="comformcaptcha"
+         name="comformcaptcha" value="%(form_captcha)s" />
+  <div class="comformhelp">%(captcha_puzzle)s</div>
+</div>
 <div class="comformbody">
   <label for="comformbody" class="comformbody">The comment
     %(form_body_error)s</label>
@@ -496,9 +530,10 @@ class Templates (object):
                return self.get_template(
                        'com_footer', default_comment_footer, comment.to_vars())
 
-       def get_comment_form(self, article, form_data):
+       def get_comment_form(self, article, form_data, captcha_puzzle):
                vars = article.to_vars()
                vars.update(form_data.to_vars(self))
+               vars['captcha_puzzle'] = captcha_puzzle
                return self.get_template(
                        'com_form', default_comment_form, vars)
 
@@ -508,12 +543,14 @@ class Templates (object):
 
 
 class CommentFormData (object):
-       def __init__(self, author = '', link = '', body = ''):
+       def __init__(self, author = '', link = '', captcha = '', body = ''):
                self.author = author
                self.link = link
+               self.captcha = captcha
                self.body = body
                self.author_error = ''
                self.link_error = ''
+               self.captcha_error = ''
                self.body_error = ''
                self.action = ''
                self.method = 'post'
@@ -522,14 +559,18 @@ class CommentFormData (object):
                render_error = template.get_comment_error
                a_error = self.author_error and render_error(self.author_error)
                l_error = self.link_error and render_error(self.link_error)
+               c_error = self.captcha_error \
+                               and render_error(self.captcha_error)
                b_error = self.body_error and render_error(self.body_error)
                return {
                        'form_author': sanitize(self.author),
                        'form_link': sanitize(self.link),
+                       'form_captcha': sanitize(self.captcha),
                        'form_body': sanitize(self.body),
 
                        'form_author_error': a_error,
                        'form_link_error': l_error,
+                       'form_captcha_error': c_error,
                        'form_body_error': b_error,
 
                        'form_action': self.action,
@@ -916,7 +957,8 @@ def render_comments(article, template, form_data):
        if not form_data:
                form_data = CommentFormData()
        form_data.action = blog_url + '/comment/' + article.uuid + '#comment'
-       print template.get_comment_form(article, form_data)             ,
+       captcha = Captcha(article)
+       print template.get_comment_form(article, form_data, captcha.puzzle)
 
 def render_html(articles, db, actyear = None, show_comments = False,
                redirect =  None, form_data = None):
@@ -1049,6 +1091,7 @@ def handle_cgi():
                        uuid = uuid.replace('/', '')
                        author = form.getfirst('comformauthor', '')
                        link = form.getfirst('comformlink', '')
+                       captcha = form.getfirst('comformcaptcha', '')
                        body = form.getfirst('comformbody', '')
 
        db = ArticleDB(os.path.join(data_path, 'db'))
@@ -1066,8 +1109,9 @@ def handle_cgi():
                render_artlist(articles, db)
        elif comment:
                form_data = CommentFormData(author.strip().replace('\n', ' '),
-                               link.strip().replace('\n', ' '), body.strip())
+                               link.strip().replace('\n', ' '), captcha, body)
                article = db.get_article(uuid)
+               captcha = Captcha(article)
                redirect = False
                valid = True
                if not form_data.author:
@@ -1081,6 +1125,9 @@ def handle_cgi():
                                form_data.link_error = 'please, enter a ' \
                                                'valid link'
                                valid = False
+               if not captcha.validate(form_data):
+                       form_data.captcha_error = captcha.help
+                       valid = False
                if not form_data.body:
                        form_data.body_error = 'please, write a comment'
                        valid = False

diff --git a/config.py.sample b/config.py.sample
index 1f2c4eac0f1f68f84eb7e8029aa3be3ee22b941d..c3b3653c845b40e75e9f93e7e4cf10a16516d933 100644 (file)
--- a/config.py.sample
+++ b/config.py.sample
@@ -36,4 +36,47 @@ 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