Introduction of TextSentinel to enforce title and body quality.

app/models/post.rb

@@ -38,6 +38,7 @@ class Post < ActiveRecord::Base
 
   validates_presence_of :raw, :user_id, :topic_id
   validates :raw, length: {in: SiteSetting.min_post_length..SiteSetting.max_post_length}
+  validate :raw_quality
   validate :max_mention_validator
   validate :max_images_validator
   validate :max_links_validator
@@ -68,6 +69,18 @@ class Post < ActiveRecord::Base
     self.raw.strip! if self.raw.present?
   end
 
+  def raw_quality
+
+    sentinel = TextSentinel.new(self.raw, min_entropy: SiteSetting.body_min_entropy)    
+    if sentinel.valid?
+      # It's possible the sentinel has cleaned up the title a bit
+      self.raw = sentinel.text 
+    else
+      errors.add(:raw, I18n.t(:is_invalid)) unless sentinel.valid?
+    end
+  end
+
+
   # Stop us from posting the same thing too quickly
   def unique_post_validator
     return if SiteSetting.unique_posts_mins == 0

app/models/site_setting.rb

@@ -126,6 +126,11 @@ class SiteSetting < ActiveRecord::Base
   setting(:basic_requires_read_posts, 100)
   setting(:basic_requires_time_spent_mins, 30)
 
+  # Entropy checks
+  setting(:title_min_entropy, 10)
+  setting(:body_min_entropy, 7)
+  setting(:max_word_length, 30)
+
 
   def self.call_mothership?
     self.enforce_global_nicknames? and self.discourse_org_access_key.present?

app/models/topic.rb

@@ -2,6 +2,7 @@ require_dependency 'slug'
 require_dependency 'avatar_lookup'
 require_dependency 'topic_view'
 require_dependency 'rate_limiter'
+require_dependency 'text_sentinel'
 
 class Topic < ActiveRecord::Base
   include RateLimiter::OnCreateRecord
@@ -18,13 +19,14 @@ class Topic < ActiveRecord::Base
   rate_limit :limit_topics_per_day
   rate_limit :limit_private_messages_per_day
 
+  validate :title_quality  
   validates_presence_of :title
   validates :title, length: {in: SiteSetting.min_topic_title_length..SiteSetting.max_topic_title_length}
 
   serialize :meta_data, ActiveRecord::Coders::Hstore
 
   validate :unique_title
-  validate :nuclear_option
+  
 
   belongs_to :category
   has_many :posts
@@ -113,18 +115,20 @@ class Topic < ActiveRecord::Base
     errors.add(:title, I18n.t(:has_already_been_used)) if finder.exists?
   end
 
-  # This is bad, but people are screwing us on try.discourse.org - soon we'll replace with
-  # a much more sane validation of odd characters to allow for other languages and such.
-  def nuclear_option
 
-    # Let presence validation catch it if it's blank
-    return if title.blank?
+  def title_quality
+    # We don't care about quality on private messages
+    return if private_message?
 
-    title.each_char do |c|
-      unless (20..126).include?(c.ord)
-        errors.add(:title, I18n.t(:invalid_characters))
-        return
-      end
+    sentinel = TextSentinel.new(title, 
+                                min_entropy: SiteSetting.title_min_entropy, 
+                                max_word_length: SiteSetting.max_word_length,
+                                remove_interior_spaces: true)
+    if sentinel.valid?
+      # It's possible the sentinel has cleaned up the title a bit
+      self.title = sentinel.text 
+    else
+      errors.add(:title, I18n.t(:is_invalid)) unless sentinel.valid?
     end
   end
 

config/locales/en.yml

@@ -9,6 +9,7 @@ en:
   just_posted_that: "is too similar to what you recently posted"
   has_already_been_used: "has already been used"
   invalid_characters: "contains invalid characters"
+  is_invalid: "is invalid; try to be a little more descriptive"
 
   activerecord:
     attributes:
@@ -302,6 +303,10 @@ en:
     email_time_window_mins: "How many minutes we wait before sending a user mail, to give them a chance to see it first."
     flush_timings_secs: "How frequently we flush timing data to the server, in seconds."
 
+    max_word_length: "The maximum word length in a topic title"
+    title_min_entropy: "The minimum entropy for a topic title"
+    body_min_entropy: "The minimum entropy for post body"
+
   # This section is exported to the javascript for i18n in the admin section
   admin_js:
     type_to_filter: "Type to Filter..."

lib/text_sentinel.rb

@@ -0,0 +1,56 @@
+require 'iconv'
+
+#
+# Given a string, tell us whether or not is acceptable. Also, remove stuff we don't like
+# such as leading / trailing space.
+#
+class TextSentinel
+
+  attr_accessor :text
+
+  def self.non_symbols_regexp
+    /[\ -\/\[-\`\:-\@\{-\~]/m
+  end
+
+  def initialize(text, opts=nil)
+    if text.present?
+      @text = Iconv.new('UTF-8//IGNORE', 'UTF-8').iconv(text.dup)
+    end
+
+    @opts = opts || {}
+
+    if @text.present?
+      @text.strip! 
+      @text.gsub!(/ +/m, ' ') if @opts[:remove_interior_spaces]
+    end
+  end
+
+  # Entropy is a number of how many unique characters the string needs. 
+  def entropy
+    return 0 if @text.blank?
+    @entropy ||= @text.each_char.to_a.uniq.size
+  end
+
+  def valid?    
+
+    # Blank strings are not valid
+    return false if @text.blank?
+
+    # Entropy check if required
+    return false if @opts[:min_entropy].present? and (entropy < @opts[:min_entropy])
+
+    # We don't have a comprehensive list of symbols, but this will eliminate some noise
+    non_symbols = @text.gsub(TextSentinel.non_symbols_regexp, '').size
+    return false if non_symbols == 0
+
+    # Don't allow super long strings without spaces
+
+    return false if @opts[:max_word_length] and @text =~ /\w{#{@opts[:max_word_length]},}(\s|$)/
+
+    # We don't allow all upper case content
+    return false if @text == @text.upcase
+
+    true
+  end
+
+end

spec/components/post_creator_spec.rb

@@ -11,7 +11,7 @@ describe PostCreator do
 
   context 'new topic' do
     let(:category) { Fabricate(:category, user: user) }
-    let(:basic_topic_params) { {title: 'hello world', raw: 'my name is fred', archetype_id: 1} }
+    let(:basic_topic_params) { {title: 'hello world topic', raw: 'my name is fred', archetype_id: 1} }
     let(:image_sizes) { {'http://an.image.host/image.jpg' => {'width' => 111, 'height' => 222}} }
 
     let(:creator) { PostCreator.new(user, basic_topic_params) }
@@ -83,7 +83,7 @@ describe PostCreator do
     let(:target_user1) { Fabricate(:coding_horror) }
     let(:target_user2) { Fabricate(:moderator) }
     let(:post) do
-      PostCreator.create(user, title: 'hi there',
+      PostCreator.create(user, title: 'hi there welcome to my topic',
                                raw: 'this is my awesome message',
                                archetype: Archetype.private_message,
                                target_usernames: [target_user1.username, target_user2.username].join(','))

spec/components/search_spec.rb

@@ -14,7 +14,7 @@ describe Search do
   context 'post indexing observer' do 
     before do 
       @category = Fabricate(:category, name: 'america')
-      @topic = Fabricate(:topic, title: 'sam test', category: @category)
+      @topic = Fabricate(:topic, title: 'sam test topic', category: @category)
       @post = Fabricate(:post, topic: @topic, raw: 'this <b>fun test</b> <img src="bla" title="my image">')
       @indexed = Topic.exec_sql("select search_data from posts_search where id = #{@post.id}").first["search_data"]
     end
@@ -29,7 +29,7 @@ describe Search do
     end
 
     it "should pick up on title updates" do 
-      @topic.title = "harpi"
+      @topic.title = "harpi is the new title"
       @topic.save!
       @indexed = Topic.exec_sql("select search_data from posts_search where id = #{@post.id}").first["search_data"]
 

spec/components/text_sentinel_spec.rb

@@ -0,0 +1,96 @@
+# encoding: utf-8
+
+require 'spec_helper'
+require 'text_sentinel'
+require 'iconv'
+
+describe TextSentinel do
+
+
+  context "entropy" do
+
+
+    it "returns 0 for an empty string" do
+      TextSentinel.new("").entropy.should == 0
+    end
+
+    it "returns 0 for a nil string" do
+      TextSentinel.new(nil).entropy.should == 0
+    end
+
+    it "returns 1 for a string with many leading spaces" do
+      TextSentinel.new((" " * 10) + "x").entropy.should == 1
+    end
+
+    it "returns 1 for one char, even repeated" do
+      TextSentinel.new("a" * 10).entropy.should == 1
+    end
+
+    it "returns an accurate count of many chars" do
+      TextSentinel.new("evil trout is evil").entropy.should == 10
+    end
+
+  end
+
+  context "cleaning up" do
+
+    it "strips leading or trailing whitespace" do
+      TextSentinel.new("   \t  test \t  ").text.should == "test"
+    end
+
+    it "allows utf-8 chars" do
+      TextSentinel.new("йȝîûηыეமிᚉ⠛").text.should == "йȝîûηыეமிᚉ⠛"
+    end
+
+    context "interior spaces" do
+
+      let(:spacey_string) { "hello     there's weird     spaces here." }
+
+      it "ignores intra spaces by default" do
+        TextSentinel.new(spacey_string).text.should == spacey_string
+      end
+
+      it "fixes intra spaces when enabled" do
+        TextSentinel.new(spacey_string, remove_interior_spaces: true).text.should == "hello there's weird spaces here."
+      end      
+
+    end
+
+  end
+
+  context "validity" do
+
+    let(:valid_string) { "This is a cool topic about Discourse" }
+
+    it "allows a valid string" do
+      TextSentinel.new(valid_string).should be_valid
+    end
+
+    it "doesn't allow all caps topics" do
+      TextSentinel.new(valid_string.upcase).should_not be_valid
+    end
+
+    it "enforces the minimum entropy" do
+      TextSentinel.new(valid_string, min_entropy: 16).should be_valid
+    end
+
+    it "enforces the minimum entropy" do      
+      TextSentinel.new(valid_string, min_entropy: 17).should_not be_valid
+    end
+
+    it "doesn't allow a long alphanumeric string with no spaces" do
+      TextSentinel.new("jfewjfoejwfojeojfoejofjeo38493824jfkjewfjeoifijeoijfoejofjeojfoewjfo834988394032jfiejoijofijeojfeojfojeofjewojfojeofjeowjfojeofjeojfoe3898439849032jfeijfwoijfoiewj",
+                      max_word_length: 30).should_not be_valid
+    end
+
+    it "doesn't except junk symbols as a string" do
+      TextSentinel.new("[[[").should_not be_valid
+      TextSentinel.new("<<<").should_not be_valid
+      TextSentinel.new("{{$!").should_not be_valid        
+    end
+
+
+  end
+
+
+end

spec/components/topic_query_spec.rb

@@ -11,11 +11,11 @@ describe TopicQuery do
   let(:admin) { Fabricate(:moderator) }
 
   context 'a bunch of topics' do
-    let!(:regular_topic) { Fabricate(:topic, title: 'regular', user: creator, bumped_at: 15.minutes.ago) }
-    let!(:pinned_topic) { Fabricate(:topic, title: 'pinned', user: creator, pinned: true, bumped_at: 10.minutes.ago) }
-    let!(:archived_topic) { Fabricate(:topic, title: 'archived', user: creator, archived: true, bumped_at: 6.minutes.ago) }
-    let!(:invisible_topic) { Fabricate(:topic, title: 'invisible', user: creator, visible: false, bumped_at: 5.minutes.ago) }
-    let!(:closed_topic) { Fabricate(:topic, title: 'closed', user: creator, closed: true, bumped_at: 1.minute.ago) }
+    let!(:regular_topic) { Fabricate(:topic, title: 'this is a regular topic', user: creator, bumped_at: 15.minutes.ago) }
+    let!(:pinned_topic) { Fabricate(:topic, title: 'this is a pinned topic', user: creator, pinned: true, bumped_at: 10.minutes.ago) }
+    let!(:archived_topic) { Fabricate(:topic, title: 'this is an archived topic', user: creator, archived: true, bumped_at: 6.minutes.ago) }
+    let!(:invisible_topic) { Fabricate(:topic, title: 'this is an invisible topic', user: creator, visible: false, bumped_at: 5.minutes.ago) }
+    let!(:closed_topic) { Fabricate(:topic, title: 'this is a closed topic', user: creator, closed: true, bumped_at: 1.minute.ago) }
 
     context 'list_popular' do
       let(:topics) { topic_query.list_popular.topics }

spec/controllers/topics_controller_spec.rb

@@ -334,9 +334,9 @@ describe TopicsController do
         end
 
         it 'allows a change of title' do
-          xhr :put, :update, topic_id: @topic.id, slug: @topic.title, title: 'new title'
+          xhr :put, :update, topic_id: @topic.id, slug: @topic.title, title: 'this is a new title for the topic'
           @topic.reload
-          @topic.title.should == 'new title'
+          @topic.title.should == 'this is a new title for the topic'
         end
 
         it 'triggers a change of category' do

spec/models/post_alert_observer_spec.rb

@@ -30,7 +30,7 @@ describe PostAlertObserver do
   context 'when editing a post' do      
     it 'notifies a user of the revision' do
       lambda {
-        post.revise(evil_trout, "world")
+        post.revise(evil_trout, "world is the new body of the message")
       }.should change(post.user.notifications, :count).by(1)
     end
   end

spec/models/topic_spec.rb

@@ -5,9 +5,6 @@ require 'spec_helper'
 describe Topic do
 
   it { should validate_presence_of :title }
-  it { should_not allow_value("x" * (SiteSetting.max_topic_title_length + 1)).for(:title) }
-  it { should_not allow_value("x").for(:title) }
-  it { should_not allow_value((" " * SiteSetting.min_topic_title_length) + "x").for(:title) }
 
   it { should belong_to :category }
   it { should belong_to :user }  
@@ -26,14 +23,26 @@ describe Topic do
 
   it { should rate_limit }
 
-  context 'topic title content' do
+  context '.title_quality' do
+
+    it "strips a title when identifying length" do
+      Fabricate.build(:topic, title: (" " * SiteSetting.min_topic_title_length) + "x").should_not be_valid
+    end
+
+    it "doesn't allow a long title" do
+      Fabricate.build(:topic, title: "x" * (SiteSetting.max_topic_title_length + 1)).should_not be_valid
+    end
+
+    it "doesn't allow a short title" do
+      Fabricate.build(:topic, title: "x" * (SiteSetting.min_topic_title_length + 1)).should_not be_valid
+    end
 
     it "allows a regular title with a few ascii characters" do
       Fabricate.build(:topic, title: "hello this is my cool topic! welcome: all;").should be_valid
     end
 
-    it "doesn't allow non standard ascii" do
-      Fabricate.build(:topic, title: "Iñtërnâtiônàlizætiøn").should_not be_valid
+    it "allows non ascii" do
+      Fabricate.build(:topic, title: "Iñtërnâtiônàlizætiøn").should be_valid
     end
 
   end
@@ -830,7 +839,7 @@ describe Topic do
 
     context 'changing title' do
       before do
-        topic.title = "new title"
+        topic.title = "new title for the topic"
         topic.save
       end