Add PPAPI decryptor implementation.

webkit/media/crypto/content_decryptor.cc

+// Copyright (c) 2012 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 <cstring>  // std::memcpy
+#include <sstream>  // std::ostringstream
+
+#include "base/compiler_specific.h"  // for OVERRIDE.
+#include "ppapi/c/pp_errors.h"
+#include "ppapi/c/pp_stdint.h"
+#include "ppapi/cpp/completion_callback.h"
+#include "ppapi/cpp/core.h"
+#include "ppapi/cpp/instance.h"
+#include "ppapi/cpp/module.h"
+#include "ppapi/cpp/pass_ref.h"
+#include "ppapi/cpp/resource.h"
+#include "ppapi/cpp/var.h"
+#include "ppapi/cpp/var_array_buffer.h"
+#include "ppapi/cpp/dev/buffer_dev.h"
+#include "ppapi/cpp/private/content_decryptor_private.h"
+#include "ppapi/utility/completion_callback_factory.h"
+
+namespace {
+
+struct DecryptorMessage {
+  DecryptorMessage() : media_error(0), system_code(0) {}
+  std::string key_system;
+  std::string session_id;
+  std::string default_url;
+  std::string message_data;
+  int32_t media_error;
+  int32_t system_code;
+};
+
+struct DecryptedBlock {
+  DecryptedBlock() : request_id(0) {}
+  int32_t request_id;
+  std::string data;
+};
+
+void CallOnMain(pp::CompletionCallback cb) {
+  pp::Module::Get()->core()->CallOnMainThread(0, cb, PP_OK);
+}
+
+}  // namespace
+
+
+// A wrapper class responsible for managing interaction between the browser and
+// a Content Decryption Module (CDM).
+class CDMWrapper : public pp::Instance,
+                   public pp::ContentDecryptor_Private {
+ public:
+  CDMWrapper(PP_Instance instance, pp::Module* module);
+  virtual ~CDMWrapper() {}
+
+  // PPP_ContentDecryptor_Private methods
+  virtual bool GenerateKeyRequest(const std::string& key_system,
+                                  pp::VarArrayBuffer init_data) OVERRIDE;
+  virtual bool AddKey(const std::string& session_id,
+                      pp::VarArrayBuffer key) OVERRIDE;
+  virtual bool CancelKeyRequest(const std::string& session_id) OVERRIDE;
+  virtual bool Decrypt(pp::Buffer_Dev encrypted_block,
+                       int32_t request_id) OVERRIDE;
+
+  virtual bool DecryptAndDecode(pp::Buffer_Dev encrypted_block,
+                                int32_t request_id) OVERRIDE {
+    return false;
+  }
+
+  virtual bool Init(uint32_t argc, const char* argn[], const char* argv[]) {
+    return true;
+  }
+
+ private:
+  PP_Resource StringToBufferResource(const std::string& str);
+
+  // <code>PPB_ContentDecryptor_Private</code> dispatchers. These are passed to
+  // <code>callback_factory_</code> to ensure that calls into
+  // <code>PPP_ContentDecryptor_Private</code> are asynchronous.
+  void NeedKey(int32_t result, const DecryptorMessage& decryptor_message);
+  void KeyAdded(int32_t result, const DecryptorMessage& decryptor_message);
+  void KeyMessage(int32_t result, const DecryptorMessage& decryptor_message);
+  void KeyError(int32_t result, const DecryptorMessage& decryptor_message);
+  void DeliverBlock(int32_t result, const DecryptedBlock& decrypted_block);
+
+  pp::CompletionCallbackFactory<CDMWrapper> callback_factory_;
+
+  virtual bool IsValidSessionId(std::string session_id) {
+    // TODO(tomfinegan): The CDM MUST handle multiple session IDs. This simple
+    // implementation exists for testing purposes.
+    return (!session_id_.empty() && session_id == session_id_);
+  }
+
+  // TODO(tomfinegan): This needs to be mappable to init data (key IDs in the
+  // WebM case). For WebM it most likely will be 1 key ID and 1 session per
+  // stream. For now we'll just use a random number.
+  uint32_t next_session_id_;
+  std::string session_id_;

[xhwang, 2012/08/15 00:27:57]

Do we need to check in these test code? The CDM will handle all of these and the
CDMWrapper should only pass them through.

[Tom Finegan, 2012/08/16 03:10:48]

Done.

+
+  // Key ID obtained from init data passed to <code>GenerateKeyRequest</code>.
+  // As-is: WebM video specific; Inadequate for WebM with encrypted audio (A/V
+  // will not have same key ID/key/session ID). Probably inadequate for ISO.
+  std::string key_id_;

[xhwang, 2012/08/15 00:27:57]

ditto

[Tom Finegan, 2012/08/16 03:10:48]

Done.

+
+  // TODO(tomfinegan): Should these be multimaps of session_id:key_system and
+  // session_id:key? Or am I completely confused? :)
+  std::string key_;
+  std::string key_system_;

[xhwang, 2012/08/15 00:27:57]

ditto

[Tom Finegan, 2012/08/16 03:10:48]

Done.

+};
+
+CDMWrapper::CDMWrapper(PP_Instance instance,
+                       pp::Module* module)
+    : pp::Instance(instance),
+      pp::ContentDecryptor_Private(this),
+      next_session_id_(0) {
+  callback_factory_.Initialize(this);
+}
+
+bool CDMWrapper::GenerateKeyRequest(const std::string& key_system,
+                                    pp::VarArrayBuffer init_data) {
+
+  // TODO(tomfinegan): Testing only implementation; init_data will not always
+  // be the key ID.
+  key_id_.assign(reinterpret_cast<char*>(init_data.Map()),
+                 init_data.ByteLength());
+  key_system_ = key_system;
+
+  if (key_id_.empty() || key_system_.empty())
+    return false;
+
+  std::ostringstream stream;
+  stream << next_session_id_++;
+  session_id_ = stream.str();
+
+  DecryptorMessage decryptor_message;
+  decryptor_message.key_system = key_system_;
+  decryptor_message.session_id = session_id_;
+  decryptor_message.default_url = "http://www.google.com";
+  decryptor_message.message_data = "key request";
+
+  CallOnMain(callback_factory_.NewCallback(&CDMWrapper::KeyMessage,
+                                           decryptor_message));
+  return true;
+}
+
+bool CDMWrapper::AddKey(const std::string& session_id,
+                        pp::VarArrayBuffer key) {
+  if (!IsValidSessionId(session_id))
+    return false;
+
+  key_.assign(reinterpret_cast<char*>(key.Map()), key.ByteLength());
+
+  DecryptorMessage decryptor_message;
+  decryptor_message.key_system = key_system_;
+  decryptor_message.session_id = session_id_;
+  CallOnMain(callback_factory_.NewCallback(&CDMWrapper::KeyAdded,
+                                           decryptor_message));
+  return true;
+}
+
+bool CDMWrapper::CancelKeyRequest(const std::string& session_id) {
+  if (!IsValidSessionId(session_id))
+    return false;
+
+  // TODO(tomfinegan): cancel pending key request in CDM.
+
+  return true;
+}
+
+bool CDMWrapper::Decrypt(pp::Buffer_Dev encrypted_block,
+                         int32_t request_id) {
+  if (!encrypted_block.data())
+    return false;
+
+  DecryptedBlock decrypted_block;
+  decrypted_block.request_id = request_id;
+  decrypted_block.data = "Pretend I'm decrypted data!";
+  CallOnMain(callback_factory_.NewCallback(&CDMWrapper::DeliverBlock,
+                                           decrypted_block));
+  return true;
+}
+
+PP_Resource CDMWrapper::StringToBufferResource(const std::string& str) {
+  if (str.empty())
+    return 0;
+
+  pp::Buffer_Dev buffer(this, str.size());
+  if (!buffer.data())
+    return 0;
+
+  std::memcpy(buffer.data(), str.data(), str.size());
+  return buffer.detach();
+}
+
+void CDMWrapper::NeedKey(int32_t result,
+                         const DecryptorMessage& decryptor_message) {
+  pp::ContentDecryptor_Private::NeedKey(decryptor_message.key_system,
+                                        decryptor_message.session_id,
+                                        decryptor_message.message_data);
+}
+
+void CDMWrapper::KeyAdded(int32_t result,
+                          const DecryptorMessage& decryptor_message) {
+  pp::ContentDecryptor_Private::KeyAdded(decryptor_message.key_system,
+                                         decryptor_message.session_id);
+}
+
+void CDMWrapper::KeyMessage(int32_t result,
+                            const DecryptorMessage& decryptor_message) {
+  pp::Buffer_Dev message_buffer(
+      StringToBufferResource(decryptor_message.message_data));
+  pp::ContentDecryptor_Private::KeyMessage(decryptor_message.key_system,
+                                           decryptor_message.session_id,
+                                           message_buffer,
+                                           decryptor_message.default_url);
+}
+
+void CDMWrapper::KeyError(int32_t result,
+                          const DecryptorMessage& decryptor_message) {
+  pp::ContentDecryptor_Private::KeyError(decryptor_message.key_system,
+                                         decryptor_message.session_id,
+                                         decryptor_message.media_error,
+                                         decryptor_message.system_code);
+}
+
+void CDMWrapper::DeliverBlock(int32_t result,
+                              const DecryptedBlock& decrypted_block) {
+  pp::Buffer_Dev decrypted_buffer(
+      StringToBufferResource(decrypted_block.data));
+  pp::ContentDecryptor_Private::DeliverBlock(decrypted_buffer,
+                                             decrypted_block.request_id);
+}
+
+// This object is the global object representing this plugin library as long
+// as it is loaded.
+class MyModule : public pp::Module {
+ public:
+  MyModule() : pp::Module() {}
+  virtual ~MyModule() {}
+
+  virtual pp::Instance* CreateInstance(PP_Instance instance) {
+    return new CDMWrapper(instance, this);
+  }
+};
+
+namespace pp {
+
+// Factory function for your specialization of the Module object.
+Module* CreateModule() {
+  return new MyModule();
+}
+
+}  // namespace pp