FIX: Invalid URLs cause post not to save

app/models/topic_link.rb

@@ -2,6 +2,9 @@ require 'uri'
 require_dependency 'slug'
 
 class TopicLink < ActiveRecord::Base
+  MAX_DOMAIN_LENGTH = 100 unless defined? MAX_DOMAIN_LENGTH
+  MAX_URL_LENGTH = 500 unless defined? MAX_URL_LENGTH
+
   belongs_to :topic
   belongs_to :user
   belongs_to :post
@@ -126,6 +129,7 @@ class TopicLink < ActiveRecord::Base
 
             # Store the canonical URL
             topic = Topic.find_by(id: topic_id)
+            topic_id = nil unless topic
 
             if topic.present?
               url = "#{Discourse.base_url}#{topic.relative_url}"
@@ -142,6 +146,9 @@ class TopicLink < ActiveRecord::Base
             reflected_post = Post.find_by(topic_id: topic_id, post_number: post_number.to_i)
           end
 
+          next if url && url.length > MAX_URL_LENGTH
+          next if parsed && parsed.host && parsed.host.length > MAX_DOMAIN_LENGTH
+
           added_urls << url
           TopicLink.create(post_id: post.id,
                            user_id: post.user_id,

spec/models/topic_link_spec.rb

@@ -26,19 +26,25 @@ describe TopicLink do
 
   describe 'external links' do
     before do
-      @post = Fabricate(:post_with_external_links, user: @user, topic: @topic)
+      @post = Fabricate(:post, raw: "
+http://a.com/
+http://b.com/b
+http://#{'a'*200}.com/invalid
+http://b.com/#{'a'*500}
+                        ", user: @user, topic: @topic)
+
       TopicLink.extract_from(@post)
     end
 
     it 'works' do
       # has the forum topic links
-      @topic.topic_links.count.should == 4
+      @topic.topic_links.count.should == 2
 
       # works with markdown links
-      @topic.topic_links.exists?(url: "http://forumwarz.com").should be_true
+      @topic.topic_links.exists?(url: "http://a.com/").should be_true
 
       #works with markdown links followed by a period
-      @topic.topic_links.exists?(url: "http://www.codinghorror.com/blog").should be_true
+      @topic.topic_links.exists?(url: "http://b.com/b").should be_true
     end
 
   end
@@ -53,9 +59,10 @@ describe TopicLink do
         @other_post = @other_topic.posts.create(user: @user, raw: "some content for the second post")
 
         @url = "http://#{test_uri.host}/t/#{@other_topic.slug}/#{@other_topic.id}/#{@other_post.post_number}"
+        @invalid_url = "http://#{test_uri.host}/t/#{@other_topic.slug}/9999999999999999999999999999999"
 
         @topic.posts.create(user: @user, raw: 'initial post')
-        @post = @topic.posts.create(user: @user, raw: "Link to another topic:\n\n#{@url}\n\n")
+        @post = @topic.posts.create(user: @user, raw: "Link to another topic:\n\n#{@url}\n\n#{@invalid_url}")
         @post.reload
 
         TopicLink.extract_from(@post)