media/cdm/proxy_decryptor.cc

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "media/cdm/proxy_decryptor.h"
   6
   7 #include <cstring>
   8
   9 #include "base/bind.h"
  10 #include "base/callback_helpers.h"
  11 #include "base/logging.h"
  12 #include "base/stl_util.h"
  13 #include "base/strings/string_util.h"
  14 #include "media/base/cdm_callback_promise.h"
  15 #include "media/base/cdm_config.h"
  16 #include "media/base/cdm_factory.h"
  17 #include "media/base/cdm_key_information.h"
  18 #include "media/base/key_systems.h"
  19 #include "media/base/media_permission.h"
  20 #include "media/cdm/json_web_key.h"
  21 #include "media/cdm/key_system_names.h"
  22
  23 namespace media {
  24
  25 // Special system code to signal a closed persistent session in a SessionError()
  26 // call. This is needed because there is no SessionClosed() call in the prefixed
  27 // EME API.
  28 const int kSessionClosedSystemCode = 29127;
  29
  30 ProxyDecryptor::PendingGenerateKeyRequestData::PendingGenerateKeyRequestData(
  31     EmeInitDataType init_data_type,
  32     const std::vector<uint8>& init_data)
  33     : init_data_type(init_data_type), init_data(init_data) {
  34 }
  35
  36 ProxyDecryptor::PendingGenerateKeyRequestData::
  37     ~PendingGenerateKeyRequestData() {
  38 }
  39
  40 ProxyDecryptor::ProxyDecryptor(MediaPermission* media_permission,
  41                                const KeyAddedCB& key_added_cb,
  42                                const KeyErrorCB& key_error_cb,
  43                                const KeyMessageCB& key_message_cb)
  44     : is_creating_cdm_(false),
  45       media_permission_(media_permission),
  46       key_added_cb_(key_added_cb),
  47       key_error_cb_(key_error_cb),
  48       key_message_cb_(key_message_cb),
  49       is_clear_key_(false),
  50       weak_ptr_factory_(this) {
  51   DCHECK(media_permission);
  52   DCHECK(!key_added_cb_.is_null());
  53   DCHECK(!key_error_cb_.is_null());
  54   DCHECK(!key_message_cb_.is_null());
  55 }
  56
  57 ProxyDecryptor::~ProxyDecryptor() {
  58   // Destroy the decryptor explicitly before destroying the plugin.
  59   media_keys_.reset();
  60 }
  61
  62 void ProxyDecryptor::CreateCdm(CdmFactory* cdm_factory,
  63                                const std::string& key_system,
  64                                const GURL& security_origin,
  65                                const CdmContextReadyCB& cdm_context_ready_cb) {
  66   DVLOG(1) << __FUNCTION__ << ": key_system = " << key_system;
  67   DCHECK(!is_creating_cdm_);
  68   DCHECK(!media_keys_);
  69
  70   // TODO(sandersd): Trigger permissions check here and use it to determine
  71   // distinctive identifier support, instead of always requiring the
  72   // permission. http://crbug.com/455271
  73   CdmConfig cdm_config;
  74   cdm_config.allow_distinctive_identifier = true;
  75   cdm_config.allow_persistent_state = true;
  76
  77   is_creating_cdm_ = true;
  78
  79   base::WeakPtr<ProxyDecryptor> weak_this = weak_ptr_factory_.GetWeakPtr();
  80   cdm_factory->Create(
  81       key_system, security_origin, cdm_config,
  82       base::Bind(&ProxyDecryptor::OnSessionMessage, weak_this),
  83       base::Bind(&ProxyDecryptor::OnSessionClosed, weak_this),
  84       base::Bind(&ProxyDecryptor::OnLegacySessionError, weak_this),
  85       base::Bind(&ProxyDecryptor::OnSessionKeysChange, weak_this),
  86       base::Bind(&ProxyDecryptor::OnSessionExpirationUpdate, weak_this),
  87       base::Bind(&ProxyDecryptor::OnCdmCreated, weak_this, key_system,
  88                  security_origin, cdm_context_ready_cb));
  89 }
  90
  91 void ProxyDecryptor::OnCdmCreated(const std::string& key_system,
  92                                   const GURL& security_origin,
  93                                   const CdmContextReadyCB& cdm_context_ready_cb,
  94                                   scoped_ptr<MediaKeys> cdm,
  95                                   const std::string& /* error_message */) {
  96   is_creating_cdm_ = false;
  97
  98   if (!cdm) {
  99     cdm_context_ready_cb.Run(nullptr);
 100   } else {
 101     key_system_ = key_system;
 102     security_origin_ = security_origin;
 103     is_clear_key_ = IsClearKey(key_system) || IsExternalClearKey(key_system);
 104     media_keys_ = cdm.Pass();
 105
 106     cdm_context_ready_cb.Run(media_keys_->GetCdmContext());
 107   }
 108
 109   for (const auto& request : pending_requests_)
 110     GenerateKeyRequestInternal(request->init_data_type, request->init_data);
 111
 112   pending_requests_.clear();
 113 }
 114
 115 void ProxyDecryptor::GenerateKeyRequest(EmeInitDataType init_data_type,
 116                                         const uint8* init_data,
 117                                         int init_data_length) {
 118   std::vector<uint8> init_data_vector(init_data, init_data + init_data_length);
 119
 120   if (is_creating_cdm_) {
 121     pending_requests_.push_back(
 122         new PendingGenerateKeyRequestData(init_data_type, init_data_vector));
 123     return;
 124   }
 125
 126   GenerateKeyRequestInternal(init_data_type, init_data_vector);
 127 }
 128
 129 // Returns true if |data| is prefixed with |header| and has data after the
 130 // |header|.
 131 bool HasHeader(const std::vector<uint8>& data, const std::string& header) {
 132   return data.size() > header.size() &&
 133          std::equal(header.begin(), header.end(), data.begin());
 134 }
 135
 136 // Removes the first |length| items from |data|.
 137 void StripHeader(std::vector<uint8>& data, size_t length) {
 138   data.erase(data.begin(), data.begin() + length);
 139 }
 140
 141 void ProxyDecryptor::GenerateKeyRequestInternal(
 142     EmeInitDataType init_data_type,
 143     const std::vector<uint8>& init_data) {
 144   DVLOG(1) << __FUNCTION__;
 145   DCHECK(!is_creating_cdm_);
 146
 147   if (!media_keys_) {
 148     OnLegacySessionError(std::string(), MediaKeys::NOT_SUPPORTED_ERROR, 0,
 149                          "CDM creation failed.");
 150     return;
 151   }
 152
 153   const char kPrefixedApiPersistentSessionHeader[] = "PERSISTENT|";
 154   const char kPrefixedApiLoadSessionHeader[] = "LOAD_SESSION|";
 155
 156   SessionCreationType session_creation_type = TemporarySession;
 157   std::vector<uint8> stripped_init_data = init_data;
 158   if (HasHeader(init_data, kPrefixedApiLoadSessionHeader)) {
 159     session_creation_type = LoadSession;
 160     StripHeader(stripped_init_data, strlen(kPrefixedApiLoadSessionHeader));
 161   } else if (HasHeader(init_data, kPrefixedApiPersistentSessionHeader)) {
 162     session_creation_type = PersistentSession;
 163     StripHeader(stripped_init_data,
 164                 strlen(kPrefixedApiPersistentSessionHeader));
 165   }
 166
 167   scoped_ptr<NewSessionCdmPromise> promise(new CdmCallbackPromise<std::string>(
 168       base::Bind(&ProxyDecryptor::SetSessionId, weak_ptr_factory_.GetWeakPtr(),
 169                  session_creation_type),
 170       base::Bind(&ProxyDecryptor::OnLegacySessionError,
 171                  weak_ptr_factory_.GetWeakPtr(),
 172                  std::string())));  // No session id until created.
 173
 174   if (session_creation_type == LoadSession) {
 175     media_keys_->LoadSession(
 176         MediaKeys::PERSISTENT_LICENSE_SESSION,
 177         std::string(
 178             reinterpret_cast<const char*>(vector_as_array(&stripped_init_data)),
 179             stripped_init_data.size()),
 180         promise.Pass());
 181     return;
 182   }
 183
 184   MediaKeys::SessionType session_type =
 185       session_creation_type == PersistentSession
 186           ? MediaKeys::PERSISTENT_LICENSE_SESSION
 187           : MediaKeys::TEMPORARY_SESSION;
 188
 189   // No permission required when AesDecryptor is used or when the key system is
 190   // external clear key.
 191   DCHECK(!key_system_.empty());
 192   if (CanUseAesDecryptor(key_system_) || IsExternalClearKey(key_system_)) {
 193     OnPermissionStatus(session_type, init_data_type, stripped_init_data,
 194                        promise.Pass(), true /* granted */);
 195     return;
 196   }
 197
 198 #if defined(OS_CHROMEOS) || defined(OS_ANDROID)
 199   media_permission_->RequestPermission(
 200       MediaPermission::PROTECTED_MEDIA_IDENTIFIER, security_origin_,
 201       base::Bind(&ProxyDecryptor::OnPermissionStatus,
 202                  weak_ptr_factory_.GetWeakPtr(), session_type, init_data_type,
 203                  stripped_init_data, base::Passed(&promise)));
 204 #else
 205   OnPermissionStatus(session_type, init_data_type, stripped_init_data,
 206                      promise.Pass(), true /* granted */);
 207 #endif
 208 }
 209
 210 void ProxyDecryptor::OnPermissionStatus(
 211     MediaKeys::SessionType session_type,
 212     EmeInitDataType init_data_type,
 213     const std::vector<uint8>& init_data,
 214     scoped_ptr<NewSessionCdmPromise> promise,
 215     bool granted) {
 216   // ProxyDecryptor is only used by Prefixed EME, where RequestPermission() is
 217   // only for triggering the permission UI. Later CheckPermission() will be
 218   // called (e.g. in PlatformVerificationFlow on ChromeOS; in BrowserCdmManager
 219   // on Android) and the permission status will be evaluated then.
 220   DVLOG_IF(1, !granted) << "Permission request rejected.";
 221
 222   media_keys_->CreateSessionAndGenerateRequest(session_type, init_data_type,
 223                                                init_data, promise.Pass());
 224 }
 225
 226 void ProxyDecryptor::AddKey(const uint8* key,
 227                             int key_length,
 228                             const uint8* init_data,
 229                             int init_data_length,
 230                             const std::string& session_id) {
 231   DVLOG(1) << "AddKey()";
 232
 233   if (!media_keys_) {
 234     OnLegacySessionError(std::string(), MediaKeys::INVALID_STATE_ERROR, 0,
 235                          "CDM is not available.");
 236     return;
 237   }
 238
 239   // In the prefixed API, the session parameter provided to addKey() is
 240   // optional, so use the single existing session if it exists.
 241   std::string new_session_id(session_id);
 242   if (new_session_id.empty()) {
 243     if (active_sessions_.size() == 1) {
 244       base::hash_map<std::string, bool>::iterator it = active_sessions_.begin();
 245       new_session_id = it->first;
 246     } else {
 247       OnLegacySessionError(std::string(), MediaKeys::NOT_SUPPORTED_ERROR, 0,
 248                            "SessionId not specified.");
 249       return;
 250     }
 251   }
 252
 253   scoped_ptr<SimpleCdmPromise> promise(new CdmCallbackPromise<>(
 254       base::Bind(&ProxyDecryptor::GenerateKeyAdded,
 255                  weak_ptr_factory_.GetWeakPtr(), session_id),
 256       base::Bind(&ProxyDecryptor::OnLegacySessionError,
 257                  weak_ptr_factory_.GetWeakPtr(), session_id)));
 258
 259   // EME WD spec only supports a single array passed to the CDM. For
 260   // Clear Key using v0.1b, both arrays are used (|init_data| is key_id).
 261   // Since the EME WD spec supports the key as a JSON Web Key,
 262   // convert the 2 arrays to a JWK and pass it as the single array.
 263   if (is_clear_key_) {
 264     // Decryptor doesn't support empty key ID (see http://crbug.com/123265).
 265     // So ensure a non-empty value is passed.
 266     if (!init_data) {
 267       static const uint8 kDummyInitData[1] = {0};
 268       init_data = kDummyInitData;
 269       init_data_length = arraysize(kDummyInitData);
 270     }
 271
 272     std::string jwk =
 273         GenerateJWKSet(key, key_length, init_data, init_data_length);
 274     DCHECK(!jwk.empty());
 275     media_keys_->UpdateSession(new_session_id,
 276                                std::vector<uint8_t>(jwk.begin(), jwk.end()),
 277                                promise.Pass());
 278     return;
 279   }
 280
 281   media_keys_->UpdateSession(new_session_id,
 282                              std::vector<uint8_t>(key, key + key_length),
 283                              promise.Pass());
 284 }
 285
 286 void ProxyDecryptor::CancelKeyRequest(const std::string& session_id) {
 287   DVLOG(1) << "CancelKeyRequest()";
 288
 289   if (!media_keys_) {
 290     OnLegacySessionError(std::string(), MediaKeys::INVALID_STATE_ERROR, 0,
 291                          "CDM is not available.");
 292     return;
 293   }
 294
 295   scoped_ptr<SimpleCdmPromise> promise(new CdmCallbackPromise<>(
 296       base::Bind(&ProxyDecryptor::OnSessionClosed,
 297                  weak_ptr_factory_.GetWeakPtr(), session_id),
 298       base::Bind(&ProxyDecryptor::OnLegacySessionError,
 299                  weak_ptr_factory_.GetWeakPtr(), session_id)));
 300   media_keys_->RemoveSession(session_id, promise.Pass());
 301 }
 302
 303 void ProxyDecryptor::OnSessionMessage(const std::string& session_id,
 304                                       MediaKeys::MessageType message_type,
 305                                       const std::vector<uint8>& message,
 306                                       const GURL& legacy_destination_url) {
 307   // Assumes that OnSessionCreated() has been called before this.
 308
 309   // For ClearKey, convert the message from JSON into just passing the key
 310   // as the message. If unable to extract the key, return the message unchanged.
 311   if (is_clear_key_) {
 312     std::vector<uint8> key;
 313     if (ExtractFirstKeyIdFromLicenseRequest(message, &key)) {
 314       key_message_cb_.Run(session_id, key, legacy_destination_url);
 315       return;
 316     }
 317   }
 318
 319   key_message_cb_.Run(session_id, message, legacy_destination_url);
 320 }
 321
 322 void ProxyDecryptor::OnSessionKeysChange(const std::string& session_id,
 323                                          bool has_additional_usable_key,
 324                                          CdmKeysInfo keys_info) {
 325   // EME v0.1b doesn't support this event.
 326 }
 327
 328 void ProxyDecryptor::OnSessionExpirationUpdate(
 329     const std::string& session_id,
 330     const base::Time& new_expiry_time) {
 331   // EME v0.1b doesn't support this event.
 332 }
 333
 334 void ProxyDecryptor::GenerateKeyAdded(const std::string& session_id) {
 335   // EME WD doesn't support this event, but it is needed for EME v0.1b.
 336   key_added_cb_.Run(session_id);
 337 }
 338
 339 void ProxyDecryptor::OnSessionClosed(const std::string& session_id) {
 340   base::hash_map<std::string, bool>::iterator it =
 341       active_sessions_.find(session_id);
 342
 343   // Latest EME spec separates closing a session ("allows an application to
 344   // indicate that it no longer needs the session") and actually closing the
 345   // session (done by the CDM at any point "such as in response to a close()
 346   // call, when the session is no longer needed, or when system resources are
 347   // lost.") Thus the CDM may cause 2 close() events -- one to resolve the
 348   // close() promise, and a second to actually close the session. Prefixed EME
 349   // only expects 1 close event, so drop the second (and subsequent) events.
 350   // However, this means we can't tell if the CDM is generating spurious close()
 351   // events.
 352   if (it == active_sessions_.end())
 353     return;
 354
 355   if (it->second) {
 356     OnLegacySessionError(session_id, MediaKeys::NOT_SUPPORTED_ERROR,
 357                          kSessionClosedSystemCode,
 358                          "Do not close persistent sessions.");
 359   }
 360   active_sessions_.erase(it);
 361 }
 362
 363 void ProxyDecryptor::OnLegacySessionError(const std::string& session_id,
 364                                           MediaKeys::Exception exception_code,
 365                                           uint32 system_code,
 366                                           const std::string& error_message) {
 367   // Convert |error_name| back to MediaKeys::KeyError if possible. Prefixed
 368   // EME has different error message, so all the specific error events will
 369   // get lost.
 370   MediaKeys::KeyError error_code;
 371   switch (exception_code) {
 372     case MediaKeys::CLIENT_ERROR:
 373       error_code = MediaKeys::kClientError;
 374       break;
 375     case MediaKeys::OUTPUT_ERROR:
 376       error_code = MediaKeys::kOutputError;
 377       break;
 378     default:
 379       // This will include all other CDM4 errors and any error generated
 380       // by CDM5 or later.
 381       error_code = MediaKeys::kUnknownError;
 382       break;
 383   }
 384   key_error_cb_.Run(session_id, error_code, system_code);
 385 }
 386
 387 void ProxyDecryptor::SetSessionId(SessionCreationType session_type,
 388                                   const std::string& session_id) {
 389   // Loaded sessions are considered persistent.
 390   bool is_persistent =
 391       session_type == PersistentSession || session_type == LoadSession;
 392   active_sessions_.insert(std::make_pair(session_id, is_persistent));
 393
 394   // For LoadSession(), generate the KeyAdded event.
 395   if (session_type == LoadSession)
 396     GenerateKeyAdded(session_id);
 397 }
 398
 399 }  // namespace media