Fix #4125: Detect forum and comment spam.

app/models/comment.rb

@@ -2,6 +2,7 @@ class Comment < ApplicationRecord
   include Mentionable
 
   validate :validate_creator_is_not_limited, :on => :create
+  validate :validate_comment_is_not_spam, on: :create
   validates_presence_of :body, :message => "has no content"
   belongs_to :post
   belongs_to_creator
@@ -124,6 +125,10 @@ class Comment < ApplicationRecord
     end
   end
 
+  def validate_comment_is_not_spam
+    errors[:base] << "Failed to create comment" if SpamDetector.new(self).spam?
+  end
+
   def update_last_commented_at_on_create
     Post.where(:id => post_id).update_all(:last_commented_at => created_at)
     if Comment.where("post_id = ?", post_id).count <= Danbooru.config.comment_threshold && !do_not_bump_post?

app/models/forum_post.rb

@@ -15,6 +15,7 @@ class ForumPost < ApplicationRecord
   after_destroy :update_topic_updated_at_on_destroy
   validates_presence_of :body
   validate :validate_topic_is_unlocked
+  validate :validate_post_is_not_spam, on: :create
   validate :topic_is_not_restricted, :on => :create
   before_destroy :validate_topic_is_unlocked
   after_save :delete_topic_if_original_post
@@ -133,6 +134,10 @@ class ForumPost < ApplicationRecord
     votes.where(creator_id: user.id, score: score).exists?
   end
 
+  def validate_post_is_not_spam
+    errors[:base] << "Failed to create forum post" if SpamDetector.new(self, user_ip: CurrentUser.ip_addr).spam?
+  end
+
   def validate_topic_is_unlocked
     return if CurrentUser.is_moderator?
     return if topic.nil?