Primitive spam filter

app/controllers/wiki_controller.rb

@@ -176,6 +176,9 @@ class WikiController < ApplicationController
     cookies['author'] = @params['author']
 
     begin
+      check_for_spam(@params['content'], remote_ip)
+      check_blocked_ips(remote_ip)
+
       if @page
         wiki.revise_page(@web_name, @page_name, @params['content'], Time.now, 
             Author.new(@params['author'], remote_ip))
@@ -228,6 +231,25 @@ class WikiController < ApplicationController
 
   private
 
+  def check_blocked_ips(ip)
+    if defined? BLOCKED_IPS and not BLOCKED_IPS.nil?
+      BLOCKED_IPS.each do |blocked_ip|
+        raise Instiki::ValidationError.new('Revision rejected by spam filter') if ip == blocked_ip
+      end
+    end
+  end
+
+  def check_for_spam(new_content, ip)
+    if defined? SPAM_PATTERNS and not SPAM_PATTERNS.nil?
+      SPAM_PATTERNS.each do |pattern|
+        if new_content =~ pattern
+          logger.info "Spam attempt from IP address #{ip}"
+          raise Instiki::ValidationError.new('Revision rejected by spam filter')
+        end
+      end
+    end
+  end
+
   def convert_tex_to_pdf(tex_path)
     # TODO remove earlier PDF files with the same prefix
     # TODO handle gracefully situation where pdflatex is not available

config/environments/production.rb

@@ -2,3 +2,14 @@ Dependencies.mechanism = :require
 ActionController::Base.consider_all_requests_local = false
 ActionController::Base.perform_caching = false
 
+
+spam_patterns_filename = RAILS_ROOT + '/config/spam_patterns.txt'
+if File.exists? spam_patterns_filename
+  SPAM_PATTERNS = File.readlines(spam_patterns_filename).select { |line| line != '' }.map { 
+      |line| Regexp.new(line) }
+end
+
+blocked_ips_filename = RAILS_ROOT + '/config/blocked_ips.txt'
+if File.exists? blocked_ips_filename
+  BLOCKED_IPS = File.readlines(blocked_ips_filename).select { |line| line != '' }
+end