gecko-dev/dom/media/AutoplayPolicy.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "AutoplayPolicy.h"

#include "mozilla/Logging.h"
#include "mozilla/Preferences.h"
#include "mozilla/dom/AudioContext.h"
#include "mozilla/dom/FeaturePolicyUtils.h"
#include "mozilla/dom/HTMLMediaElement.h"
#include "mozilla/dom/HTMLMediaElementBinding.h"
#include "mozilla/dom/UserActivation.h"
#include "nsGlobalWindowInner.h"
#include "nsIAutoplay.h"
#include "nsContentUtils.h"
#include "mozilla/dom/Document.h"
#include "MediaManager.h"
#include "nsIDocShell.h"
#include "nsIDocShellTreeItem.h"
#include "nsPIDOMWindow.h"
#include "mozilla/Services.h"
#include "mozilla/StaticPrefs_media.h"
#include "nsIPermissionManager.h"

mozilla::LazyLogModule gAutoplayPermissionLog("Autoplay");

#define AUTOPLAY_LOG(msg, ...) \
  MOZ_LOG(gAutoplayPermissionLog, LogLevel::Debug, (msg, ##__VA_ARGS__))

namespace mozilla {
namespace dom {

static Document* ApproverDocOf(const Document& aDocument) {
  nsCOMPtr<nsIDocShell> ds = aDocument.GetDocShell();
  if (!ds) {
    return nullptr;
  }

  nsCOMPtr<nsIDocShellTreeItem> rootTreeItem;
  ds->GetInProcessSameTypeRootTreeItem(getter_AddRefs(rootTreeItem));
  if (!rootTreeItem) {
    return nullptr;
  }

  return rootTreeItem->GetDocument();
}

static bool IsActivelyCapturingOrHasAPermission(nsPIDOMWindowInner* aWindow) {
  // Pages which have been granted permission to capture WebRTC camera or
  // microphone or screen are assumed to be trusted, and are allowed to
  // autoplay.
  if (MediaManager::GetIfExists()) {
    return MediaManager::GetIfExists()->IsActivelyCapturingOrHasAPermission(
        aWindow->WindowID());
  }

  auto principal = nsGlobalWindowInner::Cast(aWindow)->GetPrincipal();
  return (nsContentUtils::IsExactSitePermAllow(principal,
                                               NS_LITERAL_CSTRING("camera")) ||
          nsContentUtils::IsExactSitePermAllow(
              principal, NS_LITERAL_CSTRING("microphone")) ||
          nsContentUtils::IsExactSitePermAllow(principal,
                                               NS_LITERAL_CSTRING("screen")));
}

static uint32_t SiteAutoplayPerm(const Document* aDocument) {
  if (!aDocument) {
    return nsIPermissionManager::DENY_ACTION;
  }
  nsIPrincipal* principal = aDocument->NodePrincipal();
  nsCOMPtr<nsIPermissionManager> permMgr = services::GetPermissionManager();
  NS_ENSURE_TRUE(permMgr, nsIPermissionManager::DENY_ACTION);

  uint32_t perm;
  nsresult rv = permMgr->TestExactPermissionFromPrincipal(
      principal, NS_LITERAL_CSTRING("autoplay-media"), &perm);
  NS_ENSURE_SUCCESS(rv, nsIPermissionManager::DENY_ACTION);
  return perm;
}

static bool IsWindowAllowedToPlay(nsPIDOMWindowInner* aWindow) {
  if (!aWindow) {
    return false;
  }

  if (IsActivelyCapturingOrHasAPermission(aWindow)) {
    AUTOPLAY_LOG(
        "Allow autoplay as document has camera or microphone or screen"
        " permission.");
    return true;
  }

  RefPtr<BrowsingContext> topLevelBC = aWindow->GetBrowsingContext()->Top();
  if (topLevelBC->HasBeenUserGestureActivated()) {
    AUTOPLAY_LOG(
        "Allow autoplay as top-level context has been activated by user "
        "gesture.");
    return true;
  }

  Document* currentDoc = aWindow->GetExtantDoc();
  if (!currentDoc) {
    return false;
  }

  bool isTopLevelContent = !aWindow->GetBrowsingContext()->GetParent();
  if (currentDoc->MediaDocumentKind() == Document::MediaDocumentKind::Video &&
      isTopLevelContent) {
    AUTOPLAY_LOG("Allow top-level video document to autoplay.");
    return true;
  }

  Document* approver = ApproverDocOf(*currentDoc);
  if (!approver) {
    return false;
  }

  if (approver->IsExtensionPage()) {
    AUTOPLAY_LOG("Allow autoplay as in extension document.");
    return true;
  }

  return false;
}

static uint32_t DefaultAutoplayBehaviour() {
  int prefValue =
      Preferences::GetInt("media.autoplay.default", nsIAutoplay::ALLOWED);
  if (prefValue == nsIAutoplay::ALLOWED) {
    return nsIAutoplay::ALLOWED;
  }
  if (prefValue == nsIAutoplay::BLOCKED_ALL) {
    return nsIAutoplay::BLOCKED_ALL;
  }
  return nsIAutoplay::BLOCKED;
}

static bool IsMediaElementInaudible(const HTMLMediaElement& aElement) {
  if (aElement.Volume() == 0.0 || aElement.Muted()) {
    AUTOPLAY_LOG("Media %p is muted.", &aElement);
    return true;
  }

  if (!aElement.HasAudio() &&
      aElement.ReadyState() >= HTMLMediaElement_Binding::HAVE_METADATA) {
    AUTOPLAY_LOG("Media %p has no audio track", &aElement);
    return true;
  }

  return false;
}

static bool IsAudioContextAllowedToPlay(const AudioContext& aContext) {
  // Offline context won't directly output sound to audio devices.
  return aContext.IsOffline() ||
         IsWindowAllowedToPlay(aContext.GetParentObject());
}

static bool IsEnableBlockingWebAudioByUserGesturePolicy() {
  return Preferences::GetBool("media.autoplay.block-webaudio", false) &&
         StaticPrefs::media_autoplay_enabled_user_gestures_needed();
}

static bool IsAllowedToPlayByBlockingModel(const HTMLMediaElement& aElement) {
  if (!StaticPrefs::media_autoplay_enabled_user_gestures_needed()) {
    // If element is blessed, it would always be allowed to play().
    return aElement.IsBlessed() || UserActivation::IsHandlingUserInput();
  }
  return IsWindowAllowedToPlay(aElement.OwnerDoc()->GetInnerWindow());
}

// On GeckoView, we don't store any site's permission in permission manager, we
// would check the GV request status to know if the site can be allowed to play.
// But on other platforms, we would store the site's permission in permission
// manager.
#if defined(MOZ_WIDGET_ANDROID)
using RType = GVAutoplayRequestType;

static bool IsGVAutoplayRequestAllowed(nsPIDOMWindowInner* aWindow,
                                       RType aType) {
  if (!aWindow) {
    return false;
  }

  RefPtr<BrowsingContext> context = aWindow->GetBrowsingContext()->Top();
  GVAutoplayRequestStatus status =
      aType == RType::eAUDIBLE ? context->GetGVAudibleAutoplayRequestStatus()
                               : context->GetGVInaudibleAutoplayRequestStatus();
  return status == GVAutoplayRequestStatus::eALLOWED;
}

static bool IsGVAutoplayRequestAllowed(const HTMLMediaElement& aElement) {
  // On GV, blocking model is the first thing we would check inside Gecko, and
  // if the media is not allowed by that, then we would check the response from
  // the embedding app to decide the final result.
  if (IsAllowedToPlayByBlockingModel(aElement)) {
    return true;
  }

  RefPtr<nsPIDOMWindowInner> window = aElement.OwnerDoc()->GetInnerWindow();
  if (!window) {
    return false;
  }

  const RType type =
      IsMediaElementInaudible(aElement) ? RType::eINAUDIBLE : RType::eAUDIBLE;
  return IsGVAutoplayRequestAllowed(window, type);
}
#endif

static bool IsAllowedToPlayInternal(const HTMLMediaElement& aElement) {
#if defined(MOZ_WIDGET_ANDROID)
  if (StaticPrefs::media_geckoview_autoplay_request()) {
    return IsGVAutoplayRequestAllowed(aElement);
  }
#endif
  Document* approver = ApproverDocOf(*aElement.OwnerDoc());

  bool isInaudible = IsMediaElementInaudible(aElement);
  bool isUsingAutoplayModel = IsAllowedToPlayByBlockingModel(aElement);

  uint32_t defaultBehaviour = DefaultAutoplayBehaviour();
  uint32_t sitePermission = SiteAutoplayPerm(approver);

  AUTOPLAY_LOG(
      "IsAllowedToPlayInternal, isInaudible=%d,"
      "isUsingAutoplayModel=%d, sitePermission=%d, defaultBehaviour=%d",
      isInaudible, isUsingAutoplayModel, sitePermission, defaultBehaviour);

  // For site permissions we store permissionManager values except
  // for BLOCKED_ALL, for the default pref values we store
  // nsIAutoplay values.
  if (sitePermission == nsIPermissionManager::ALLOW_ACTION) {
    return true;
  }

  if (sitePermission == nsIPermissionManager::DENY_ACTION) {
    return isInaudible || isUsingAutoplayModel;
  }

  if (sitePermission == nsIAutoplay::BLOCKED_ALL) {
    return isUsingAutoplayModel;
  }

  if (defaultBehaviour == nsIAutoplay::ALLOWED) {
    return true;
  }

  if (defaultBehaviour == nsIAutoplay::BLOCKED) {
    return isInaudible || isUsingAutoplayModel;
  }

  MOZ_ASSERT(defaultBehaviour == nsIAutoplay::BLOCKED_ALL);
  return isUsingAutoplayModel;
}

/* static */
bool AutoplayPolicy::IsAllowedToPlay(const HTMLMediaElement& aElement) {
  const bool result = IsAllowedToPlayInternal(aElement);
  AUTOPLAY_LOG("IsAllowedToPlay, mediaElement=%p, isAllowToPlay=%s", &aElement,
               result ? "allowed" : "blocked");
  return result;
}

/* static */
bool AutoplayPolicy::IsAllowedToPlay(const AudioContext& aContext) {
  /**
   * The autoplay checking has 5 different phases,
   * 1. check whether audio context itself meets the autoplay condition
   * 2. check if we enable blocking web audio or not
   *    (only support blocking when using user-gesture-activation model)
   * 3. check whether the site is in the autoplay whitelist
   * 4. check global autoplay setting and check wether the site is in the
   *    autoplay blacklist.
   * 5. check whether media is allowed under current blocking model
   *    (only support user-gesture-activation model)
   */
  if (aContext.IsOffline()) {
    return true;
  }

  if (!IsEnableBlockingWebAudioByUserGesturePolicy()) {
    return true;
  }

  nsPIDOMWindowInner* window = aContext.GetParentObject();
  Document* approver = aContext.GetParentObject()
                           ? ApproverDocOf(*(window->GetExtantDoc()))
                           : nullptr;
  uint32_t sitePermission = SiteAutoplayPerm(approver);

  if (sitePermission == nsIPermissionManager::ALLOW_ACTION) {
    AUTOPLAY_LOG(
        "Allow autoplay as document has permanent autoplay permission.");
    return true;
  }

  if (DefaultAutoplayBehaviour() == nsIAutoplay::ALLOWED &&
      sitePermission != nsIPermissionManager::DENY_ACTION &&
      sitePermission != nsIAutoplay::BLOCKED_ALL) {
    AUTOPLAY_LOG(
        "Allow autoplay as global autoplay setting is allowing autoplay by "
        "default.");
    return true;
  }

  return IsWindowAllowedToPlay(window);
}

/* static */
DocumentAutoplayPolicy AutoplayPolicy::IsAllowedToPlay(
    const Document& aDocument) {
#if defined(MOZ_WIDGET_ANDROID)
  if (StaticPrefs::media_geckoview_autoplay_request()) {
    nsPIDOMWindowInner* window = aDocument.GetInnerWindow();
    if (IsGVAutoplayRequestAllowed(window, RType::eAUDIBLE)) {
      return DocumentAutoplayPolicy::Allowed;
    }

    if (IsGVAutoplayRequestAllowed(window, RType::eINAUDIBLE)) {
      return DocumentAutoplayPolicy::Allowed_muted;
    }

    return DocumentAutoplayPolicy::Disallowed;
  }
#endif
  if (DefaultAutoplayBehaviour() == nsIAutoplay::ALLOWED ||
      IsWindowAllowedToPlay(aDocument.GetInnerWindow())) {
    return DocumentAutoplayPolicy::Allowed;
  }

  if (DefaultAutoplayBehaviour() == nsIAutoplay::BLOCKED) {
    return DocumentAutoplayPolicy::Allowed_muted;
  }

  return DocumentAutoplayPolicy::Disallowed;
}

/* static */
bool AutoplayPolicyTelemetryUtils::WouldBeAllowedToPlayIfAutoplayDisabled(
    const HTMLMediaElement& aElement) {
  return IsMediaElementInaudible(aElement) ||
         IsWindowAllowedToPlay(aElement.OwnerDoc()->GetInnerWindow());
}

/* static */
bool AutoplayPolicyTelemetryUtils::WouldBeAllowedToPlayIfAutoplayDisabled(
    const AudioContext& aContext) {
  return IsAudioContextAllowedToPlay(aContext);
}

}  // namespace dom
}  // namespace mozilla