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

/*
 * Copyright (C) 2013 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "modules/encryptedmedia/MediaKeys.h"

#include "bindings/core/v8/ScriptState.h"
#include "core/dom/DOMArrayBuffer.h"
#include "core/dom/DOMException.h"
#include "core/dom/ExceptionCode.h"
#include "core/dom/ExecutionContext.h"
#include "core/html/HTMLMediaElement.h"
#include "modules/encryptedmedia/EncryptedMediaUtils.h"
#include "modules/encryptedmedia/MediaKeySession.h"
#include "modules/encryptedmedia/SimpleContentDecryptionModuleResultPromise.h"
#include "platform/Timer.h"
#include "public/platform/WebContentDecryptionModule.h"
#include "wtf/RefPtr.h"
#include <memory>

#define MEDIA_KEYS_LOG_LEVEL 3

namespace blink {

// A class holding a pending action.
class MediaKeys::PendingAction final
    : public GarbageCollected<MediaKeys::PendingAction> {
 public:
  const Persistent<ContentDecryptionModuleResult> result() const {
    return m_result;
  }

  DOMArrayBuffer* data() const { return m_data; }

  static PendingAction* CreatePendingSetServerCertificate(
      ContentDecryptionModuleResult* result,
      DOMArrayBuffer* serverCertificate) {
    DCHECK(result);
    DCHECK(serverCertificate);
    return new PendingAction(result, serverCertificate);
  }

  DEFINE_INLINE_TRACE() {
    visitor->trace(m_result);
    visitor->trace(m_data);
  }

 private:
  PendingAction(ContentDecryptionModuleResult* result, DOMArrayBuffer* data)
      : m_result(result), m_data(data) {}

  const Member<ContentDecryptionModuleResult> m_result;
  const Member<DOMArrayBuffer> m_data;
};

// This class wraps the promise resolver used when setting the certificate
// and is passed to Chromium to fullfill the promise. This implementation of
// complete() will resolve the promise with true, while completeWithError()
// will reject the promise with an exception. completeWithSession()
// is not expected to be called, and will reject the promise.
class SetCertificateResultPromise
    : public ContentDecryptionModuleResultPromise {
 public:
  SetCertificateResultPromise(ScriptState* scriptState)
      : ContentDecryptionModuleResultPromise(scriptState) {}

  ~SetCertificateResultPromise() override {}

  // ContentDecryptionModuleResult implementation.
  void complete() override { resolve(true); }

  void completeWithError(WebContentDecryptionModuleException exceptionCode,
                         unsigned long systemCode,
                         const WebString& errorMessage) override {
    // The EME spec specifies that "If the Key System implementation does
    // not support server certificates, return a promise resolved with
    // false." So convert any NOTSUPPORTEDERROR into resolving with false.
    if (exceptionCode == WebContentDecryptionModuleExceptionNotSupportedError) {
      resolve(false);
      return;
    }

    ContentDecryptionModuleResultPromise::completeWithError(
        exceptionCode, systemCode, errorMessage);
  }
};

MediaKeys* MediaKeys::create(
    ExecutionContext* context,
    const WebVector<WebEncryptedMediaSessionType>& supportedSessionTypes,
    std::unique_ptr<WebContentDecryptionModule> cdm) {
  MediaKeys* mediaKeys =
      new MediaKeys(context, supportedSessionTypes, std::move(cdm));
  mediaKeys->suspendIfNeeded();
  return mediaKeys;
}

MediaKeys::MediaKeys(
    ExecutionContext* context,
    const WebVector<WebEncryptedMediaSessionType>& supportedSessionTypes,
    std::unique_ptr<WebContentDecryptionModule> cdm)
    : ActiveScriptWrappable(this),
      ActiveDOMObject(context),
      m_supportedSessionTypes(supportedSessionTypes),
      m_cdm(std::move(cdm)),
      m_mediaElement(nullptr),
      m_reservedForMediaElement(false),
      m_timer(this, &MediaKeys::timerFired) {
  DVLOG(MEDIA_KEYS_LOG_LEVEL) << __func__ << "(" << this << ")";
}

MediaKeys::~MediaKeys() {
  DVLOG(MEDIA_KEYS_LOG_LEVEL) << __func__ << "(" << this << ")";
}

MediaKeySession* MediaKeys::createSession(ScriptState* scriptState,
                                          const String& sessionTypeString,
                                          ExceptionState& exceptionState) {
  DVLOG(MEDIA_KEYS_LOG_LEVEL) << __func__ << "(" << this << ") "
                              << sessionTypeString;

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

  // When this method is invoked, the user agent must run the following steps:
  // 1. If this object's persistent state allowed value is false and
  //    sessionType is not "temporary", throw a new DOMException whose name is
  //    NotSupportedError.
  //    (Chromium ensures that only session types supported by the
  //    configuration are listed in supportedSessionTypes.)
  // 2. If the Key System implementation represented by this object's cdm
  //    implementation value does not support sessionType, throw a new
  //    DOMException whose name is NotSupportedError.
  WebEncryptedMediaSessionType sessionType =
      EncryptedMediaUtils::convertToSessionType(sessionTypeString);
  if (!sessionTypeSupported(sessionType)) {
    exceptionState.throwDOMException(NotSupportedError,
                                     "Unsupported session type.");
    return nullptr;
  }

  // 3. Let session be a new MediaKeySession object, and initialize it as
  //    follows:
  //    (Initialization is performed in the constructor.)
  // 4. Return session.
  return MediaKeySession::create(scriptState, this, sessionType);
}

ScriptPromise MediaKeys::setServerCertificate(
    ScriptState* scriptState,
    const DOMArrayPiece& serverCertificate) {
  // From https://w3c.github.io/encrypted-media/#setServerCertificate
  // The setServerCertificate(serverCertificate) method provides a server
  // certificate to be used to encrypt messages to the license server.
  // It must run the following steps:
  // 1. If serverCertificate is an empty array, return a promise rejected
  //    with a new DOMException whose name is "InvalidAccessError".
  if (!serverCertificate.byteLength()) {
    return ScriptPromise::rejectWithDOMException(
        scriptState,
        DOMException::create(InvalidAccessError,
                             "The serverCertificate parameter is empty."));
  }

  // 2. If the keySystem does not support server certificates, return a
  //    promise rejected with a new DOMException whose name is
  //    "NotSupportedError".
  //    (Let the CDM decide whether to support this or not.)

  // 3. Let certificate be a copy of the contents of the serverCertificate
  //    parameter.
  DOMArrayBuffer* serverCertificateBuffer = DOMArrayBuffer::create(
      serverCertificate.data(), serverCertificate.byteLength());

  // 4. Let promise be a new promise.
  SetCertificateResultPromise* result =
      new SetCertificateResultPromise(scriptState);
  ScriptPromise promise = result->promise();

  // 5. Run the following steps asynchronously (documented in timerFired()).
  m_pendingActions.append(PendingAction::CreatePendingSetServerCertificate(
      result, serverCertificateBuffer));
  if (!m_timer.isActive())
    m_timer.startOneShot(0, BLINK_FROM_HERE);

  // 6. Return promise.
  return promise;
}

bool MediaKeys::reserveForMediaElement(HTMLMediaElement* mediaElement) {
  // If some other HtmlMediaElement already has a reference to us, fail.
  if (m_mediaElement)
    return false;

  m_mediaElement = mediaElement;
  m_reservedForMediaElement = true;
  return true;
}

void MediaKeys::acceptReservation() {
  m_reservedForMediaElement = false;
}

void MediaKeys::cancelReservation() {
  m_reservedForMediaElement = false;
  m_mediaElement.clear();
}

void MediaKeys::clearMediaElement() {
  DCHECK(m_mediaElement);
  m_mediaElement.clear();
}

bool MediaKeys::sessionTypeSupported(WebEncryptedMediaSessionType sessionType) {
  for (size_t i = 0; i < m_supportedSessionTypes.size(); i++) {
    if (m_supportedSessionTypes[i] == sessionType)
      return true;
  }

  return false;
}

void MediaKeys::timerFired(TimerBase*) {
  DCHECK(m_pendingActions.size());

  // Swap the queue to a local copy to avoid problems if resolving promises
  // run synchronously.
  HeapDeque<Member<PendingAction>> pendingActions;
  pendingActions.swap(m_pendingActions);

  while (!pendingActions.isEmpty()) {
    PendingAction* action = pendingActions.takeFirst();
    DVLOG(MEDIA_KEYS_LOG_LEVEL) << __func__ << "(" << this << ") Certificate";

    // 5.1 Let cdm be the cdm during the initialization of this object.
    WebContentDecryptionModule* cdm = contentDecryptionModule();

    // 5.2 Use the cdm to process certificate.
    cdm->setServerCertificate(
        static_cast<unsigned char*>(action->data()->data()),
        action->data()->byteLength(), action->result()->result());
    // 5.3 If any of the preceding steps failed, reject promise with a
    //     new DOMException whose name is the appropriate error name.
    // 5.4 Resolve promise.
    // (These are handled by Chromium and the CDM.)
  }
}

WebContentDecryptionModule* MediaKeys::contentDecryptionModule() {
  return m_cdm.get();
}

DEFINE_TRACE(MediaKeys) {
  visitor->trace(m_pendingActions);
  visitor->trace(m_mediaElement);
  ActiveDOMObject::trace(visitor);
}

void MediaKeys::contextDestroyed() {
  ActiveDOMObject::contextDestroyed();

  // We don't need the CDM anymore. Only destroyed after all related
  // ActiveDOMObjects have been stopped.
  m_cdm.reset();
}

bool MediaKeys::hasPendingActivity() const {
  // Remain around if there are pending events.
  DVLOG(MEDIA_KEYS_LOG_LEVEL)
      << __func__ << "(" << this << ")"
      << (!m_pendingActions.isEmpty() ? " !m_pendingActions.isEmpty()" : "")
      << (m_reservedForMediaElement ? " m_reservedForMediaElement" : "");

  return !m_pendingActions.isEmpty() || m_reservedForMediaElement;
}

void MediaKeys::stop() {
  ActiveDOMObject::stop();

  if (m_timer.isActive())
    m_timer.stop();
  m_pendingActions.clear();
}

}  // namespace blink