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/strings/string_util.h"
  13 #include "media/base/cdm_callback_promise.h"
  14 #include "media/base/cdm_factory.h"
  15 #include "media/base/cdm_key_information.h"
  16 #include "media/base/key_systems.h"
  17 #include "media/base/media_permission.h"
  18 #include "media/cdm/json_web_key.h"
  19 #include "media/cdm/key_system_names.h"
  20
  21 namespace media {
  22
  23 // Special system code to signal a closed persistent session in a SessionError()
  24 // call. This is needed because there is no SessionClosed() call in the prefixed
  25 // EME API.
  26 const int kSessionClosedSystemCode = 29127;
  27
  28 ProxyDecryptor::ProxyDecryptor(MediaPermission* media_permission,
  29                                const KeyAddedCB& key_added_cb,
  30                                const KeyErrorCB& key_error_cb,
  31                                const KeyMessageCB& key_message_cb)
  32     : key_added_cb_(key_added_cb),
  33       key_error_cb_(key_error_cb),
  34       key_message_cb_(key_message_cb),
  35       is_clear_key_(false),
  36       weak_ptr_factory_(this) {
  37   DCHECK(media_permission);
  38   DCHECK(!key_added_cb_.is_null());
  39   DCHECK(!key_error_cb_.is_null());
  40   DCHECK(!key_message_cb_.is_null());
  41 }
  42
  43 ProxyDecryptor::~ProxyDecryptor() {
  44   // Destroy the decryptor explicitly before destroying the plugin.
  45   media_keys_.reset();
  46 }
  47
  48 CdmContext* ProxyDecryptor::GetCdmContext() {
  49   return media_keys_ ? media_keys_->GetCdmContext() : nullptr;
  50 }
  51
  52 bool ProxyDecryptor::InitializeCDM(CdmFactory* cdm_factory,
  53                                    const std::string& key_system,
  54                                    const GURL& security_origin) {
  55   DVLOG(1) << "InitializeCDM: key_system = " << key_system;
  56
  57   DCHECK(!media_keys_);
  58   media_keys_ = CreateMediaKeys(cdm_factory, key_system, security_origin);
  59   if (!media_keys_)
  60     return false;
  61
  62   is_clear_key_ =
  63       IsClearKey(key_system) || IsExternalClearKey(key_system);
  64   return true;
  65 }
  66
  67 // Returns true if |data| is prefixed with |header| and has data after the
  68 // |header|.
  69 bool HasHeader(const uint8* data, int data_length, const std::string& header) {
  70   return static_cast<size_t>(data_length) > header.size() &&
  71          std::equal(data, data + header.size(), header.begin());
  72 }
  73
  74 // Removes the first |length| items from |data|.
  75 void StripHeader(std::vector<uint8>& data, size_t length) {
  76   data.erase(data.begin(), data.begin() + length);
  77 }
  78
  79 bool ProxyDecryptor::GenerateKeyRequest(const std::string& init_data_type,
  80                                         const uint8* init_data,
  81                                         int init_data_length) {
  82   DVLOG(1) << "GenerateKeyRequest()";
  83   const char kPrefixedApiPersistentSessionHeader[] = "PERSISTENT|";
  84   const char kPrefixedApiLoadSessionHeader[] = "LOAD_SESSION|";
  85
  86   SessionCreationType session_creation_type = TemporarySession;
  87   std::vector<uint8> init_data_vector(init_data, init_data + init_data_length);
  88   if (HasHeader(init_data, init_data_length, kPrefixedApiLoadSessionHeader)) {
  89     session_creation_type = LoadSession;
  90     StripHeader(init_data_vector, strlen(kPrefixedApiLoadSessionHeader));
  91   } else if (HasHeader(init_data,
  92                        init_data_length,
  93                        kPrefixedApiPersistentSessionHeader)) {
  94     session_creation_type = PersistentSession;
  95     StripHeader(init_data_vector, strlen(kPrefixedApiPersistentSessionHeader));
  96   }
  97
  98   scoped_ptr<NewSessionCdmPromise> promise(
  99       new CdmCallbackPromise<std::string>(
 100           base::Bind(&ProxyDecryptor::SetSessionId,
 101                      weak_ptr_factory_.GetWeakPtr(),
 102                      session_creation_type),
 103           base::Bind(&ProxyDecryptor::OnSessionError,
 104                      weak_ptr_factory_.GetWeakPtr(),
 105                      std::string())));  // No session id until created.
 106   uint8* init_data_vector_data =
 107       (init_data_vector.size() > 0) ? &init_data_vector[0] : nullptr;
 108
 109   if (session_creation_type == LoadSession) {
 110     media_keys_->LoadSession(
 111         MediaKeys::PERSISTENT_LICENSE_SESSION,
 112         std::string(reinterpret_cast<const char*>(init_data_vector_data),
 113                     init_data_vector.size()),
 114         promise.Pass());
 115     return true;
 116   }
 117
 118   MediaKeys::SessionType session_type =
 119       session_creation_type == PersistentSession
 120           ? MediaKeys::PERSISTENT_LICENSE_SESSION
 121           : MediaKeys::TEMPORARY_SESSION;
 122
 123   media_keys_->CreateSessionAndGenerateRequest(
 124       session_type, init_data_type, init_data_vector_data,
 125       init_data_vector.size(), promise.Pass());
 126   return true;
 127 }
 128
 129 void ProxyDecryptor::AddKey(const uint8* key,
 130                             int key_length,
 131                             const uint8* init_data,
 132                             int init_data_length,
 133                             const std::string& session_id) {
 134   DVLOG(1) << "AddKey()";
 135
 136   // In the prefixed API, the session parameter provided to addKey() is
 137   // optional, so use the single existing session if it exists.
 138   std::string new_session_id(session_id);
 139   if (new_session_id.empty()) {
 140     if (active_sessions_.size() == 1) {
 141       base::hash_map<std::string, bool>::iterator it = active_sessions_.begin();
 142       new_session_id = it->first;
 143     } else {
 144       OnSessionError(std::string(),
 145                      MediaKeys::NOT_SUPPORTED_ERROR,
 146                      0,
 147                      "SessionId not specified.");
 148       return;
 149     }
 150   }
 151
 152   scoped_ptr<SimpleCdmPromise> promise(new CdmCallbackPromise<>(
 153       base::Bind(&ProxyDecryptor::GenerateKeyAdded,
 154                  weak_ptr_factory_.GetWeakPtr(), session_id),
 155       base::Bind(&ProxyDecryptor::OnSessionError,
 156                  weak_ptr_factory_.GetWeakPtr(), session_id)));
 157
 158   // EME WD spec only supports a single array passed to the CDM. For
 159   // Clear Key using v0.1b, both arrays are used (|init_data| is key_id).
 160   // Since the EME WD spec supports the key as a JSON Web Key,
 161   // convert the 2 arrays to a JWK and pass it as the single array.
 162   if (is_clear_key_) {
 163     // Decryptor doesn't support empty key ID (see http://crbug.com/123265).
 164     // So ensure a non-empty value is passed.
 165     if (!init_data) {
 166       static const uint8 kDummyInitData[1] = {0};
 167       init_data = kDummyInitData;
 168       init_data_length = arraysize(kDummyInitData);
 169     }
 170
 171     std::string jwk =
 172         GenerateJWKSet(key, key_length, init_data, init_data_length);
 173     DCHECK(!jwk.empty());
 174     media_keys_->UpdateSession(new_session_id,
 175                                reinterpret_cast<const uint8*>(jwk.data()),
 176                                jwk.size(), promise.Pass());
 177     return;
 178   }
 179
 180   media_keys_->UpdateSession(new_session_id, key, key_length, promise.Pass());
 181 }
 182
 183 void ProxyDecryptor::CancelKeyRequest(const std::string& session_id) {
 184   DVLOG(1) << "CancelKeyRequest()";
 185
 186   scoped_ptr<SimpleCdmPromise> promise(new CdmCallbackPromise<>(
 187       base::Bind(&ProxyDecryptor::OnSessionClosed,
 188                  weak_ptr_factory_.GetWeakPtr(), session_id),
 189       base::Bind(&ProxyDecryptor::OnSessionError,
 190                  weak_ptr_factory_.GetWeakPtr(), session_id)));
 191   media_keys_->RemoveSession(session_id, promise.Pass());
 192 }
 193
 194 scoped_ptr<MediaKeys> ProxyDecryptor::CreateMediaKeys(
 195     CdmFactory* cdm_factory,
 196     const std::string& key_system,
 197     const GURL& security_origin) {
 198   base::WeakPtr<ProxyDecryptor> weak_this = weak_ptr_factory_.GetWeakPtr();
 199   return cdm_factory->Create(
 200       key_system,
 201       security_origin,
 202       base::Bind(&ProxyDecryptor::OnSessionMessage, weak_this),
 203       base::Bind(&ProxyDecryptor::OnSessionClosed, weak_this),
 204       base::Bind(&ProxyDecryptor::OnSessionError, weak_this),
 205       base::Bind(&ProxyDecryptor::OnSessionKeysChange, weak_this),
 206       base::Bind(&ProxyDecryptor::OnSessionExpirationUpdate, weak_this));
 207 }
 208
 209 void ProxyDecryptor::OnSessionMessage(const std::string& session_id,
 210                                       MediaKeys::MessageType message_type,
 211                                       const std::vector<uint8>& message,
 212                                       const GURL& legacy_destination_url) {
 213   // Assumes that OnSessionCreated() has been called before this.
 214
 215   // For ClearKey, convert the message from JSON into just passing the key
 216   // as the message. If unable to extract the key, return the message unchanged.
 217   if (is_clear_key_) {
 218     std::vector<uint8> key;
 219     if (ExtractFirstKeyIdFromLicenseRequest(message, &key)) {
 220       key_message_cb_.Run(session_id, key, legacy_destination_url);
 221       return;
 222     }
 223   }
 224
 225   key_message_cb_.Run(session_id, message, legacy_destination_url);
 226 }
 227
 228 void ProxyDecryptor::OnSessionKeysChange(const std::string& session_id,
 229                                          bool has_additional_usable_key,
 230                                          CdmKeysInfo keys_info) {
 231   // EME v0.1b doesn't support this event.
 232 }
 233
 234 void ProxyDecryptor::OnSessionExpirationUpdate(
 235     const std::string& session_id,
 236     const base::Time& new_expiry_time) {
 237   // EME v0.1b doesn't support this event.
 238 }
 239
 240 void ProxyDecryptor::GenerateKeyAdded(const std::string& session_id) {
 241   // EME WD doesn't support this event, but it is needed for EME v0.1b.
 242   key_added_cb_.Run(session_id);
 243 }
 244
 245 void ProxyDecryptor::OnSessionClosed(const std::string& session_id) {
 246   base::hash_map<std::string, bool>::iterator it =
 247       active_sessions_.find(session_id);
 248
 249   // Latest EME spec separates closing a session ("allows an application to
 250   // indicate that it no longer needs the session") and actually closing the
 251   // session (done by the CDM at any point "such as in response to a close()
 252   // call, when the session is no longer needed, or when system resources are
 253   // lost.") Thus the CDM may cause 2 close() events -- one to resolve the
 254   // close() promise, and a second to actually close the session. Prefixed EME
 255   // only expects 1 close event, so drop the second (and subsequent) events.
 256   // However, this means we can't tell if the CDM is generating spurious close()
 257   // events.
 258   if (it == active_sessions_.end())
 259     return;
 260
 261   if (it->second) {
 262     OnSessionError(session_id, MediaKeys::NOT_SUPPORTED_ERROR,
 263                    kSessionClosedSystemCode,
 264                    "Do not close persistent sessions.");
 265   }
 266   active_sessions_.erase(it);
 267 }
 268
 269 void ProxyDecryptor::OnSessionError(const std::string& session_id,
 270                                     MediaKeys::Exception exception_code,
 271                                     uint32 system_code,
 272                                     const std::string& error_message) {
 273   // Convert |error_name| back to MediaKeys::KeyError if possible. Prefixed
 274   // EME has different error message, so all the specific error events will
 275   // get lost.
 276   MediaKeys::KeyError error_code;
 277   switch (exception_code) {
 278     case MediaKeys::CLIENT_ERROR:
 279       error_code = MediaKeys::kClientError;
 280       break;
 281     case MediaKeys::OUTPUT_ERROR:
 282       error_code = MediaKeys::kOutputError;
 283       break;
 284     default:
 285       // This will include all other CDM4 errors and any error generated
 286       // by CDM5 or later.
 287       error_code = MediaKeys::kUnknownError;
 288       break;
 289   }
 290   key_error_cb_.Run(session_id, error_code, system_code);
 291 }
 292
 293 void ProxyDecryptor::SetSessionId(SessionCreationType session_type,
 294                                   const std::string& session_id) {
 295   // Loaded sessions are considered persistent.
 296   bool is_persistent =
 297       session_type == PersistentSession || session_type == LoadSession;
 298   active_sessions_.insert(std::make_pair(session_id, is_persistent));
 299
 300   // For LoadSession(), generate the KeyAdded event.
 301   if (session_type == LoadSession)
 302     GenerateKeyAdded(session_id);
 303 }
 304
 305 }  // namespace media