Fix an open redirect issue in Phame with "View Live"

Summary: Currently, you can set a blog URI to "evil.com" and then the live controller will issue a redirect. Instead, require a CSRF check. If it fails, pop a "this blog has moved" dialog.

Test Plan:
  - Clicked "View Live" for in-app and on-domain blogs and posts.
  - Hit URI directly.

{F33302}

Reviewers: vrana

Reviewed By: vrana

CC: cbg, aran

Differential Revision: https://secure.phabricator.com/D5021

src/applications/phame/controller/blog/PhameBlogLiveController.php

@@ -30,8 +30,23 @@ final class PhameBlogLiveController extends PhameController {
     }
 
     if ($blog->getDomain() && ($request->getHost() != $blog->getDomain())) {
-      return id(new AphrontRedirectResponse())
-        ->setURI('http://'.$blog->getDomain().'/'.$this->more);
+      $base_uri = 'http://'.$blog->getDomain().'/';
+      if ($request->isFormPost()) {
+        return id(new AphrontRedirectResponse())
+          ->setURI($base_uri.$this->more);
+      } else {
+        // If we don't have CSRF, return a dialog instead of automatically
+        // redirecting, to prevent this endpoint from serving semi-open
+        // redirects.
+        $dialog = id(new AphrontDialogView())
+          ->setTitle(pht('Blog Moved'))
+          ->setUser($user)
+          ->appendChild(
+            pht('This blog is now hosted at %s.',
+              $base_uri))
+          ->addSubmitButton(pht('Continue'));
+        return id(new AphrontDialogResponse())->setDialog($dialog);
+      }
     }
 
     $phame_request = clone $request;

src/applications/phame/controller/blog/PhameBlogViewController.php

@@ -133,8 +133,10 @@ final class PhameBlogViewController extends PhameController {
 
     $actions->addAction(
       id(new PhabricatorActionView())
+        ->setUser($user)
         ->setIcon('world')
         ->setHref($this->getApplicationURI('live/'.$blog->getID().'/'))
+        ->setRenderAsForm(true)
         ->setName(pht('View Live')));
 
     $actions->addAction(

src/applications/phame/controller/post/PhamePostViewController.php

@@ -139,9 +139,11 @@ final class PhamePostViewController extends PhameController {
 
     $actions->addAction(
       id(new PhabricatorActionView())
+        ->setUser($user)
         ->setIcon('world')
         ->setHref($live_uri)
         ->setName(pht('View Live'))
+        ->setRenderAsForm(true)
         ->setDisabled(!$can_view_live)
         ->setWorkflow(!$can_view_live));