Always serve "{meme ...}" from the CDN domain, never from the primary domain

Summary:
Ref T13101. This is a minimal change to make "{meme ...}" work with the new Content-Security-Policy by using an Ajax request to generate the image and then swapping the source on the client.

This could be much cleaner (see T5258, etc).

Test Plan: Used `{meme, src=cat6, above=i am, below=cat}`, chuckled completely unironically.

Maniphest Tasks: T13101

Differential Revision: https://secure.phabricator.com/D19196

src/applications/macro/controller/PhabricatorMacroMemeController.php

@@ -13,18 +13,25 @@ final class PhabricatorMacroMemeController
     $lower_text = $request->getStr('lowertext');
     $viewer = $request->getViewer();
 
-    $uri = self::generateMacro($viewer, $macro_name,
-      $upper_text, $lower_text);
-    if ($uri === false) {
-      return new Aphront404Response();
-    }
-    return id(new AphrontRedirectResponse())
-      ->setIsExternal(true)
-      ->setURI($uri);
+    $uri = self::generateMacro(
+      $viewer,
+      $macro_name,
+      $upper_text,
+      $lower_text);
+
+    $content = array(
+      'imageURI' => $uri,
+    );
+
+    return id(new AphrontAjaxResponse())->setContent($content);
   }
 
-  public static function generateMacro($viewer, $macro_name, $upper_text,
-      $lower_text) {
+  public static function generateMacro(
+    PhabricatorUser $viewer,
+    $macro_name,
+    $upper_text,
+    $lower_text) {
+
     $macro = id(new PhabricatorMacroQuery())
       ->setViewer($viewer)
       ->withNames(array($macro_name))
@@ -35,34 +42,75 @@ final class PhabricatorMacroMemeController
     }
     $file = $macro->getFile();
 
-    $upper_text = strtoupper($upper_text);
-    $lower_text = strtoupper($lower_text);
-    $mixed_text = md5($upper_text).':'.md5($lower_text);
-    $hash = 'meme'.hash('sha256', $mixed_text);
-    $xform = id(new PhabricatorTransformedFile())
-      ->loadOneWhere('originalphid=%s and transform=%s',
-        $file->getPHID(), $hash);
+    $upper_text = phutil_utf8_strtoupper($upper_text);
+    $lower_text = phutil_utf8_strtoupper($lower_text);
 
-    if ($xform) {
-      $memefile = id(new PhabricatorFileQuery())
-        ->setViewer($viewer)
-        ->withPHIDs(array($xform->getTransformedPHID()))
-        ->executeOne();
-      if ($memefile) {
-        return $memefile->getBestURI();
-      }
+    $hash = PhabricatorHash::digestForIndex(
+      phutil_json_encode(
+        array(
+          'kind' => 'meme',
+          'upper' => $upper_text,
+          'lower' => $lower_text,
+        )));
+
+    $xfile = self::loadTransformedFile($viewer, $file->getPHID(), $hash);
+    if ($xfile) {
+      return $xfile->getViewURI();
     }
 
-    $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
-    $transformers = (new PhabricatorImageTransformer());
-    $newfile = $transformers
-      ->executeMemeTransform($file, $upper_text, $lower_text);
-    $xfile = new PhabricatorTransformedFile();
-    $xfile->setOriginalPHID($file->getPHID());
-    $xfile->setTransformedPHID($newfile->getPHID());
-    $xfile->setTransform($hash);
-    $xfile->save();
+    $transformer = new PhabricatorImageTransformer();
 
-    return $newfile->getBestURI();
+    $new_file = $transformer->executeMemeTransform(
+      $file,
+      $upper_text,
+      $lower_text);
+
+    $xfile = id(new PhabricatorTransformedFile())
+      ->setOriginalPHID($file->getPHID())
+      ->setTransformedPHID($new_file->getPHID())
+      ->setTransform($hash);
+
+    try {
+      $caught = null;
+
+      $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
+      try {
+        $xfile->save();
+      } catch (Exception $ex) {
+        $caught = $ex;
+      }
+      unset($unguarded);
+
+      if ($caught) {
+        throw $caught;
+      }
+
+      return $new_file->getViewURI();
+    } catch (AphrontDuplicateKeyQueryException $ex) {
+      $xfile = self::loadTransformedFile($viewer, $file->getPHID(), $hash);
+      if (!$xfile) {
+        throw $ex;
+      }
+      return $xfile->getViewURI();
+    }
+  }
+
+  private static function loadTransformedFile(
+    PhabricatorUser $viewer,
+    $file_phid,
+    $hash) {
+
+    $xform = id(new PhabricatorTransformedFile())->loadOneWhere(
+      'originalPHID = %s AND transform = %s',
+      $file_phid,
+      $hash);
+    if (!$xform) {
+      return null;
+    }
+
+    return id(new PhabricatorFileQuery())
+      ->setViewer($viewer)
+      ->withPHIDs(array($xform->getTransformedPHID()))
+      ->executeOne();
   }
 }

src/applications/macro/markup/PhabricatorMemeRemarkupRule.php

@@ -50,13 +50,10 @@ final class PhabricatorMemeRemarkupRule extends PhutilRemarkupRule {
         $options['above'],
         $options['below']);
 
-      $img = $this->newTag(
-        'img',
-        array(
-          'src' => $uri,
-          'alt' => $alt_text,
-          'class' => 'phabricator-remarkup-macro',
-        ));
+      $img = id(new PHUIRemarkupImageView())
+        ->setURI($uri)
+        ->addClass('phabricator-remarkup-macro')
+        ->setAlt($alt_text);
     }
 
     return $this->getEngine()->storeText($img);

src/infrastructure/markup/view/PHUIRemarkupImageView.php

@@ -7,6 +7,7 @@ final class PHUIRemarkupImageView
   private $width;
   private $height;
   private $alt;
+  private $classes = array();
 
   public function setURI($uri) {
     $this->uri = $uri;
@@ -44,6 +45,11 @@ final class PHUIRemarkupImageView
     return $this->alt;
   }
 
+  public function addClass($class) {
+    $this->classes[] = $class;
+    return $this;
+  }
+
   public function render() {
     $id = celerity_generate_unique_node_id();
 
@@ -54,6 +60,11 @@ final class PHUIRemarkupImageView
         'imageID' => $id,
       ));
 
+    $classes = null;
+    if ($this->classes) {
+      $classes = implode(' ', $this->classes);
+    }
+
     return phutil_tag(
       'img',
       array(
@@ -61,6 +72,7 @@ final class PHUIRemarkupImageView
         'width' => $this->getWidth(),
         'height' => $this->getHeight(),
         'alt' => $this->getAlt(),
+        'class' => $classes,
       ));
   }