third_party/WebKit/Source/modules/encryptedmedia/HTMLMediaElementEncryptedMedia.cpp

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "modules/encryptedmedia/HTMLMediaElementEncryptedMedia.h"

#include "bindings/core/v8/ExceptionState.h"
#include "bindings/core/v8/ScriptPromise.h"
#include "bindings/core/v8/ScriptPromiseResolver.h"
#include "bindings/core/v8/V8ThrowDOMException.h"
#include "core/dom/DOMException.h"
#include "core/dom/ExceptionCode.h"
#include "core/html/media/HTMLMediaElement.h"
#include "core/inspector/ConsoleMessage.h"
#include "core/typed_arrays/DOMTypedArray.h"
#include "modules/encryptedmedia/ContentDecryptionModuleResultPromise.h"
#include "modules/encryptedmedia/EncryptedMediaUtils.h"
#include "modules/encryptedmedia/MediaEncryptedEvent.h"
#include "modules/encryptedmedia/MediaKeys.h"
#include "platform/ContentDecryptionModuleResult.h"
#include "platform/bindings/ScriptState.h"
#include "platform/wtf/Functional.h"
#include "platform/wtf/text/StringBuilder.h"
#include "public/platform/TaskType.h"

#define EME_LOG_LEVEL 3

namespace blink {

// This class allows MediaKeys to be set asynchronously.
class SetMediaKeysHandler : public ScriptPromiseResolver {
  WTF_MAKE_NONCOPYABLE(SetMediaKeysHandler);

 public:
  static ScriptPromise Create(ScriptState*, HTMLMediaElement&, MediaKeys*);
  ~SetMediaKeysHandler() override;

  void Trace(blink::Visitor*) override;

 private:
  SetMediaKeysHandler(ScriptState*, HTMLMediaElement&, MediaKeys*);
  void TimerFired(TimerBase*);

  void ClearExistingMediaKeys();
  void SetNewMediaKeys();

  void Finish();
  void Fail(ExceptionCode, const String& error_message);

  void ClearFailed(ExceptionCode, const String& error_message);
  void SetFailed(ExceptionCode, const String& error_message);

  // Keep media element alive until promise is fulfilled
  Member<HTMLMediaElement> element_;
  Member<MediaKeys> new_media_keys_;
  bool made_reservation_;
  TaskRunnerTimer<SetMediaKeysHandler> timer_;
};

typedef base::OnceCallback<void()> SuccessCallback;
typedef base::OnceCallback<void(ExceptionCode, const String&)> FailureCallback;

// Represents the result used when setContentDecryptionModule() is called.
// Calls |success| if result is resolved, |failure| if result is rejected.
class SetContentDecryptionModuleResult final
    : public ContentDecryptionModuleResult {
 public:
  SetContentDecryptionModuleResult(SuccessCallback success,
                                   FailureCallback failure)
      : success_callback_(std::move(success)),
        failure_callback_(std::move(failure)) {}

  // ContentDecryptionModuleResult implementation.
  void Complete() override {
    DVLOG(EME_LOG_LEVEL) << __func__ << ": promise resolved.";
    std::move(success_callback_).Run();
  }

  void CompleteWithContentDecryptionModule(
      WebContentDecryptionModule*) override {
    NOTREACHED();
    std::move(failure_callback_)
        .Run(kInvalidStateError, "Unexpected completion.");
  }

  void CompleteWithSession(
      WebContentDecryptionModuleResult::SessionStatus status) override {
    NOTREACHED();
    std::move(failure_callback_)
        .Run(kInvalidStateError, "Unexpected completion.");
  }

  void CompleteWithKeyStatus(
      WebEncryptedMediaKeyInformation::KeyStatus key_status) override {
    NOTREACHED();
    std::move(failure_callback_)
        .Run(kInvalidStateError, "Unexpected completion.");
  }

  void CompleteWithError(WebContentDecryptionModuleException code,
                         unsigned long system_code,
                         const WebString& message) override {
    // Non-zero |systemCode| is appended to the |message|. If the |message|
    // is empty, we'll report "Rejected with system code (systemCode)".
    StringBuilder result;
    result.Append(message);
    if (system_code != 0) {
      if (result.IsEmpty())
        result.Append("Rejected with system code");
      result.Append(" (");
      result.AppendNumber(system_code);
      result.Append(')');
    }

    DVLOG(EME_LOG_LEVEL) << __func__ << ": promise rejected with code " << code
                         << " and message: " << result.ToString();

    std::move(failure_callback_)
        .Run(WebCdmExceptionToExceptionCode(code), result.ToString());
  }

 private:
  SuccessCallback success_callback_;
  FailureCallback failure_callback_;
};

ScriptPromise SetMediaKeysHandler::Create(ScriptState* script_state,
                                          HTMLMediaElement& element,
                                          MediaKeys* media_keys) {
  SetMediaKeysHandler* handler =
      new SetMediaKeysHandler(script_state, element, media_keys);
  handler->PauseIfNeeded();
  handler->KeepAliveWhilePending();
  return handler->Promise();
}

SetMediaKeysHandler::SetMediaKeysHandler(ScriptState* script_state,
                                         HTMLMediaElement& element,
                                         MediaKeys* media_keys)
    : ScriptPromiseResolver(script_state),
      element_(element),
      new_media_keys_(media_keys),
      made_reservation_(false),
      timer_(ExecutionContext::From(script_state)
                 ->GetTaskRunner(TaskType::kMiscPlatformAPI),
             this,
             &SetMediaKeysHandler::TimerFired) {
  DVLOG(EME_LOG_LEVEL) << __func__;

  // 5. Run the following steps in parallel.
  timer_.StartOneShot(TimeDelta(), FROM_HERE);
}

SetMediaKeysHandler::~SetMediaKeysHandler() = default;

void SetMediaKeysHandler::TimerFired(TimerBase*) {
  ClearExistingMediaKeys();
}

void SetMediaKeysHandler::ClearExistingMediaKeys() {
  DVLOG(EME_LOG_LEVEL) << __func__;
  HTMLMediaElementEncryptedMedia& this_element =
      HTMLMediaElementEncryptedMedia::From(*element_);

  // 5.1 If mediaKeys is not null, the CDM instance represented by
  //     mediaKeys is already in use by another media element, and
  //     the user agent is unable to use it with this element, let
  //     this object's attaching media keys value be false and
  //     reject promise with a QuotaExceededError.
  if (new_media_keys_) {
    if (!new_media_keys_->ReserveForMediaElement(element_.Get())) {
      this_element.is_attaching_media_keys_ = false;
      Fail(kQuotaExceededError,
           "The MediaKeys object is already in use by another media element.");
      return;
    }
    // Note that |m_newMediaKeys| is now considered reserved for
    // |m_element|, so it needs to be accepted or cancelled.
    made_reservation_ = true;
  }

  // 5.2 If the mediaKeys attribute is not null, run the following steps:
  if (this_element.media_keys_) {
    WebMediaPlayer* media_player = element_->GetWebMediaPlayer();
    if (media_player) {
      // 5.2.1 If the user agent or CDM do not support removing the
      //       association, let this object's attaching media keys
      //       value be false and reject promise with a NotSupportedError.
      // 5.2.2 If the association cannot currently be removed,
      //       let this object's attaching media keys value be false
      //       and reject promise with an InvalidStateError.
      // 5.2.3 Stop using the CDM instance represented by the mediaKeys
      //       attribute to decrypt media data and remove the association
      //       with the media element.
      // (All 3 steps handled as needed in Chromium.)
      SuccessCallback success_callback = WTF::Bind(
          &SetMediaKeysHandler::SetNewMediaKeys, WrapPersistent(this));
      FailureCallback failure_callback =
          WTF::Bind(&SetMediaKeysHandler::ClearFailed, WrapPersistent(this));
      ContentDecryptionModuleResult* result =
          new SetContentDecryptionModuleResult(std::move(success_callback),
                                               std::move(failure_callback));
      media_player->SetContentDecryptionModule(nullptr, result->Result());

      // Don't do anything more until |result| is resolved (or rejected).
      return;
    }
  }

  // MediaKeys not currently set or no player connected, so continue on.
  SetNewMediaKeys();
}

void SetMediaKeysHandler::SetNewMediaKeys() {
  DVLOG(EME_LOG_LEVEL) << __func__;

  // 5.3 If mediaKeys is not null, run the following steps:
  if (new_media_keys_) {
    // 5.3.1 Associate the CDM instance represented by mediaKeys with the
    //       media element for decrypting media data.
    // 5.3.2 If the preceding step failed, run the following steps:
    //       (done in setFailed()).
    // 5.3.3 Queue a task to run the Attempt to Resume Playback If Necessary
    //       algorithm on the media element.
    //       (Handled in Chromium).
    if (element_->GetWebMediaPlayer()) {
      SuccessCallback success_callback =
          WTF::Bind(&SetMediaKeysHandler::Finish, WrapPersistent(this));
      FailureCallback failure_callback =
          WTF::Bind(&SetMediaKeysHandler::SetFailed, WrapPersistent(this));
      ContentDecryptionModuleResult* result =
          new SetContentDecryptionModuleResult(std::move(success_callback),
                                               std::move(failure_callback));
      element_->GetWebMediaPlayer()->SetContentDecryptionModule(
          new_media_keys_->ContentDecryptionModule(), result->Result());

      // Don't do anything more until |result| is resolved (or rejected).
      return;
    }
  }

  // MediaKeys doesn't need to be set on the player, so continue on.
  Finish();
}

void SetMediaKeysHandler::Finish() {
  DVLOG(EME_LOG_LEVEL) << __func__;
  HTMLMediaElementEncryptedMedia& this_element =
      HTMLMediaElementEncryptedMedia::From(*element_);

  // 5.4 Set the mediaKeys attribute to mediaKeys.
  if (this_element.media_keys_)
    this_element.media_keys_->ClearMediaElement();
  this_element.media_keys_ = new_media_keys_;
  if (made_reservation_)
    new_media_keys_->AcceptReservation();

  // 5.5 Let this object's attaching media keys value be false.
  this_element.is_attaching_media_keys_ = false;

  // 5.6 Resolve promise with undefined.
  Resolve();
}

void SetMediaKeysHandler::Fail(ExceptionCode code,
                               const String& error_message) {
  // Reset ownership of |m_newMediaKeys|.
  if (made_reservation_)
    new_media_keys_->CancelReservation();

  // Make sure attaching media keys value is false.
  DCHECK(!HTMLMediaElementEncryptedMedia::From(*element_)
              .is_attaching_media_keys_);

  // Reject promise with an appropriate error.
  ScriptState::Scope scope(GetScriptState());
  v8::Isolate* isolate = GetScriptState()->GetIsolate();
  Reject(V8ThrowDOMException::CreateDOMException(isolate, code, error_message));
}

void SetMediaKeysHandler::ClearFailed(ExceptionCode code,
                                      const String& error_message) {
  DVLOG(EME_LOG_LEVEL) << __func__ << "(" << code << ", " << error_message
                       << ")";
  HTMLMediaElementEncryptedMedia& this_element =
      HTMLMediaElementEncryptedMedia::From(*element_);

  // 5.2.4 If the preceding step failed, let this object's attaching media
  //      keys value be false and reject promise with an appropriate
  //      error name.
  this_element.is_attaching_media_keys_ = false;
  Fail(code, error_message);
}

void SetMediaKeysHandler::SetFailed(ExceptionCode code,
                                    const String& error_message) {
  DVLOG(EME_LOG_LEVEL) << __func__ << "(" << code << ", " << error_message
                       << ")";
  HTMLMediaElementEncryptedMedia& this_element =
      HTMLMediaElementEncryptedMedia::From(*element_);

  // 5.3.2 If the preceding step failed (in setContentDecryptionModule()
  //       called from setNewMediaKeys()), run the following steps:
  // 5.3.2.1 Set the mediaKeys attribute to null.
  this_element.media_keys_.Clear();

  // 5.3.2.2 Let this object's attaching media keys value be false.
  this_element.is_attaching_media_keys_ = false;

  // 5.3.2.3 Reject promise with a new DOMException whose name is the
  //         appropriate error name.
  Fail(code, error_message);
}

void SetMediaKeysHandler::Trace(blink::Visitor* visitor) {
  visitor->Trace(element_);
  visitor->Trace(new_media_keys_);
  ScriptPromiseResolver::Trace(visitor);
}

HTMLMediaElementEncryptedMedia::HTMLMediaElementEncryptedMedia(
    HTMLMediaElement& element)
    : media_element_(&element),
      is_waiting_for_key_(false),
      is_attaching_media_keys_(false) {}

HTMLMediaElementEncryptedMedia::~HTMLMediaElementEncryptedMedia() {
  DVLOG(EME_LOG_LEVEL) << __func__;
}

const char* HTMLMediaElementEncryptedMedia::SupplementName() {
  return "HTMLMediaElementEncryptedMedia";
}

HTMLMediaElementEncryptedMedia& HTMLMediaElementEncryptedMedia::From(
    HTMLMediaElement& element) {
  HTMLMediaElementEncryptedMedia* supplement =
      static_cast<HTMLMediaElementEncryptedMedia*>(
          Supplement<HTMLMediaElement>::From(element, SupplementName()));
  if (!supplement) {
    supplement = new HTMLMediaElementEncryptedMedia(element);
    ProvideTo(element, SupplementName(), supplement);
  }
  return *supplement;
}

MediaKeys* HTMLMediaElementEncryptedMedia::mediaKeys(
    HTMLMediaElement& element) {
  HTMLMediaElementEncryptedMedia& this_element =
      HTMLMediaElementEncryptedMedia::From(element);
  return this_element.media_keys_.Get();
}

ScriptPromise HTMLMediaElementEncryptedMedia::setMediaKeys(
    ScriptState* script_state,
    HTMLMediaElement& element,
    MediaKeys* media_keys) {
  HTMLMediaElementEncryptedMedia& this_element =
      HTMLMediaElementEncryptedMedia::From(element);
  DVLOG(EME_LOG_LEVEL) << __func__ << ": current("
                       << this_element.media_keys_.Get() << "), new("
                       << media_keys << ")";

  // From http://w3c.github.io/encrypted-media/#setMediaKeys

  // 1. If this object's attaching media keys value is true, return a
  //    promise rejected with an InvalidStateError.
  if (this_element.is_attaching_media_keys_) {
    return ScriptPromise::RejectWithDOMException(
        script_state, DOMException::Create(kInvalidStateError,
                                           "Another request is in progress."));
  }

  // 2. If mediaKeys and the mediaKeys attribute are the same object,
  //    return a resolved promise.
  if (this_element.media_keys_ == media_keys)
    return ScriptPromise::CastUndefined(script_state);

  // 3. Let this object's attaching media keys value be true.
  this_element.is_attaching_media_keys_ = true;

  // 4. Let promise be a new promise. Remaining steps done in handler.
  return SetMediaKeysHandler::Create(script_state, element, media_keys);
}

// Create a MediaEncryptedEvent for WD EME.
static Event* CreateEncryptedEvent(WebEncryptedMediaInitDataType init_data_type,
                                   const unsigned char* init_data,
                                   unsigned init_data_length) {
  MediaEncryptedEventInit initializer;
  initializer.setInitDataType(
      EncryptedMediaUtils::ConvertFromInitDataType(init_data_type));
  initializer.setInitData(DOMArrayBuffer::Create(init_data, init_data_length));
  initializer.setBubbles(false);
  initializer.setCancelable(false);

  return MediaEncryptedEvent::Create(EventTypeNames::encrypted, initializer);
}

void HTMLMediaElementEncryptedMedia::Encrypted(
    WebEncryptedMediaInitDataType init_data_type,
    const unsigned char* init_data,
    unsigned init_data_length) {
  DVLOG(EME_LOG_LEVEL) << __func__;

  Event* event;
  if (media_element_->IsMediaDataCORSSameOrigin(
          media_element_->GetExecutionContext()->GetSecurityOrigin())) {
    event = CreateEncryptedEvent(init_data_type, init_data, init_data_length);
  } else {
    // Current page is not allowed to see content from the media file,
    // so don't return the initData. However, they still get an event.
    event = CreateEncryptedEvent(WebEncryptedMediaInitDataType::kUnknown,
                                 nullptr, 0);
    media_element_->GetExecutionContext()->AddConsoleMessage(
        ConsoleMessage::Create(kJSMessageSource, kWarningMessageLevel,
                               "Media element must be CORS-same-origin with "
                               "the embedding page. If cross-origin, you "
                               "should use the `crossorigin` attribute and "
                               "make sure CORS headers on the media data "
                               "response are CORS-same-origin."));
  }

  event->SetTarget(media_element_);
  media_element_->ScheduleEvent(event);
}

void HTMLMediaElementEncryptedMedia::DidBlockPlaybackWaitingForKey() {
  DVLOG(EME_LOG_LEVEL) << __func__;

  // From https://w3c.github.io/encrypted-media/#queue-waitingforkey:
  // It should only be called when the HTMLMediaElement object is potentially
  // playing and its readyState is equal to HAVE_FUTURE_DATA or greater.
  // FIXME: Is this really required?

  // 1. Let the media element be the specified HTMLMediaElement object.
  // 2. If the media element's waiting for key value is false, queue a task
  //    to fire a simple event named waitingforkey at the media element.
  if (!is_waiting_for_key_) {
    Event* event = Event::Create(EventTypeNames::waitingforkey);
    event->SetTarget(media_element_);
    media_element_->ScheduleEvent(event);
  }

  // 3. Set the media element's waiting for key value to true.
  is_waiting_for_key_ = true;

  // 4. Suspend playback.
  //    (Already done on the Chromium side by the decryptors.)
}

void HTMLMediaElementEncryptedMedia::DidResumePlaybackBlockedForKey() {
  DVLOG(EME_LOG_LEVEL) << __func__;

  // Logic is on the Chromium side to attempt to resume playback when a new
  // key is available. However, |m_isWaitingForKey| needs to be cleared so
  // that a later waitingForKey() call can generate the event.
  is_waiting_for_key_ = false;
}

WebContentDecryptionModule*
HTMLMediaElementEncryptedMedia::ContentDecryptionModule() {
  return media_keys_ ? media_keys_->ContentDecryptionModule() : nullptr;
}

void HTMLMediaElementEncryptedMedia::Trace(blink::Visitor* visitor) {
  visitor->Trace(media_element_);
  visitor->Trace(media_keys_);
  Supplement<HTMLMediaElement>::Trace(visitor);
}

}  // namespace blink