image/ImageBlocker.cpp

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this
   3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 #include "ImageBlocker.h"
   6 #include "nsIPermissionManager.h"
   7 #include "nsContentUtils.h"
   8 #include "mozilla/StaticPrefs_permissions.h"
   9 #include "nsNetUtil.h"
  10
  11 using namespace mozilla;
  12 using namespace mozilla::image;
  13
  14 NS_IMPL_ISUPPORTS(ImageBlocker, nsIContentPolicy)
  15
  16 NS_IMETHODIMP
  17 ImageBlocker::ShouldLoad(nsIURI* aContentLocation, nsILoadInfo* aLoadInfo,
  18                          int16_t* aShouldLoad) {
  19   *aShouldLoad = nsIContentPolicy::ACCEPT;
  20
  21   if (!aContentLocation) {
  22     // Bug 1720280: Ideally we should block the load, but to avoid a potential
  23     // null pointer deref, we return early in this case. Please note that
  24     // the ImageBlocker only applies about http/https loads anyway.
  25     return NS_OK;
  26   }
  27
  28   ExtContentPolicyType contentType = aLoadInfo->GetExternalContentPolicyType();
  29   if (contentType != ExtContentPolicy::TYPE_IMAGE &&
  30       contentType != ExtContentPolicy::TYPE_IMAGESET) {
  31     return NS_OK;
  32   }
  33
  34   if (ImageBlocker::ShouldBlock(aContentLocation)) {
  35     NS_SetRequestBlockingReason(
  36         aLoadInfo, nsILoadInfo::BLOCKING_REASON_CONTENT_POLICY_CONTENT_BLOCKED);
  37     *aShouldLoad = nsIContentPolicy::REJECT_TYPE;
  38   }
  39
  40   return NS_OK;
  41 }
  42
  43 NS_IMETHODIMP
  44 ImageBlocker::ShouldProcess(nsIURI* aContentLocation, nsILoadInfo* aLoadInfo,
  45                             int16_t* aShouldProcess) {
  46   // We block images at load level already, so those should not end up here.
  47   *aShouldProcess = nsIContentPolicy::ACCEPT;
  48   return NS_OK;
  49 }
  50
  51 /* static */
  52 bool ImageBlocker::ShouldBlock(nsIURI* aContentLocation) {
  53   // Block loading images depending on the permissions.default.image pref.
  54   if (StaticPrefs::permissions_default_image() !=
  55       nsIPermissionManager::DENY_ACTION) {
  56     return false;
  57   }
  58
  59   // we only want to check http, https
  60   // for chrome:// and resources and others, no need to check.
  61   return aContentLocation->SchemeIs("http") ||
  62          aContentLocation->SchemeIs("https");
  63 }