Farmville uses new image links

We received some feedback to our previous post. Farmville changed the links to the images, we didn't recognize this, because almost every image of every item loaded using the old image url.

We took the time and checked the diffrences today and we are going to explain it now.
The old images had the form of http://static-2.farmville.com/v36206/assets/animals/animal_horse_red_icon.png, you could build them using the items.xml. For explanation look at http://fvinternals.blogspot.com/2010/08/viewing-items-as-html-using-xslt.html
The new images are now using a hashed itemname in the form
http://static-0.farmville.com/prod/hashed/assets/animals/c5153828b93c6ea1259d7e0b7cd8c4a2.png.

Our first approach was to identify a rule for generating these hashes by logic. During our tests, we recognized, that every change in the items.xml lead to a non-hashed request. The idea was: "Is Farmville using a Hashtable?". So we were looking for new files which involve these hashes, but couldn't find something.

The next step was to reverse engineering the flash file of today. We couldn't find any free decompiler, so we used a shareware version of swf-kit to decompile it. Looking around we found the function for building the strings.

static public final function getAssetURL(param1:String) : String {
   if (AssetHashMap.hasOwnProperty(param1)) {
      param1 = GlobalEngine.getAssetUrl(AssetHashMap[param1]);
   } else {
      param1 = GlobalEngine.getAssetUrl(param1);
   }
   return param1;
}

We were right, FV is really using a Hashtable to map the images. The Hashmap is an object in the Displays package and has the format imageicon:hashimage and looks like this.

Display.AssetHashMap = {"assets/decorations/deco_bushgoose_icon.png":"assets/decorations/fe7cde4c1df363c2696423483e626da2.png", "assets/decorations/flags/flag_alpha_i_icon.png":"assets/decorations/flags/9cd115ac353499e998a24f25b17c8dc7.png", "assets/flowers/flower_lily_icon.png":"assets/flowers/2f2b4a9ef50f24d156e71d884fe4a336.png",
...
};

We uploaded the actual Hashmap, so you can download it from here.

The bad news are, that you have to decompile the swf on each update, to get the hashmap.