#2426 refactor to use predetermined referer

app/logical/image_proxy.rb

@@ -0,0 +1,34 @@
+class ImageProxy
+  def self.needs_proxy?(url)
+    fake_referer_for(url).present?
+  end
+
+  def self.fake_referer_for(url)
+    Sources::Site.new(url).strategy.fake_referer
+  end
+
+  def self.get_image(url)
+    if url.blank?
+      raise "Must specify url"
+    end
+
+    if !needs_proxy?(url)
+      raise "Proxy not allowed for this site"
+    end
+
+    uri = URI.parse(url)
+    headers = {
+      "Referer" => fake_referer_for(url),
+      "User-Agent" => "#{Danbooru.config.safe_app_name}/#{Danbooru.config.version}"
+    }
+
+    Net::HTTP.start(uri.host, uri.port) do |http|
+      resp = http.request_get(uri.request_uri, headers)
+      if resp.is_a?(Net::HTTPSuccess)
+        return resp
+      else
+        raise "HTTP error code: #{resp.code} #{resp.message}"
+      end
+    end
+  end
+end

app/logical/sources/strategies/base.rb

@@ -74,6 +74,11 @@ module Sources
         [image_url]
       end
 
+      # Should be set to a url for sites that prevent hotlinking, or left nil for sites that don't.
+      def fake_referer
+        nil
+      end
+
     protected
       def agent
         raise NotImplementedError

app/logical/sources/strategies/pixiv.rb

@@ -6,7 +6,7 @@ module Sources
   module Strategies
     class Pixiv < Base
       attr_reader :zip_url, :ugoira_frame_data, :ugoira_content_type
-      
+
       MONIKER   = '(?:[a-zA-Z0-9_-]+)'
       TIMESTAMP = '(?:[0-9]{4}/[0-9]{2}/[0-9]{2}/[0-9]{2}/[0-9]{2}/[0-9]{2})'
       EXT = "(?:jpg|jpeg|png|gif)"
@@ -35,6 +35,10 @@ module Sources
         @pixiv_moniker
       end
 
+      def fake_referer
+        "http://www.pixiv.net"
+      end
+
       def has_artist_commentary?
         @artist_commentary_desc.present?
       end