Add PPAPI decryptor interfaces.

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 <cassert>

[dmichael (off chromium), 2012/08/08 22:24:02]

I don't think you're using this?

[Tom Finegan, 2012/08/09 22:45:17]

Removed.

+#include <string>
+
+#include "base/basictypes.h"
+#include "base/string_number_conversions.h"
+#include "base/memory/scoped_ptr.h"

[dmichael (off chromium), 2012/08/08 22:24:02]

you aren't using this. I'd suggest trying to not use base if you can help it.
You might want a DEPS rule for this to make sure you only rely on ppapi/c and
ppapi/cpp.

[Tom Finegan, 2012/08/09 22:45:17]

Done.

+#include "ppapi/c/pp_errors.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/dev/content_decryptor_dev.h"
+#include "ppapi/utility/completion_callback_factory.h"
+
+namespace {
+
+struct DecryptorMessage {
+  DecryptorMessage() : media_error(0), system_error(0) {}
+  std::string key_system;
+  std::string session_id;
+  std::string default_url;
+  std::string message_data;
+  uint16 media_error;
+  uint16 system_error;
+};
+
+struct DecryptedBlock {
+  DecryptedBlock() : request_id(0) {}
+  uint64_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_Dev {
+ public:
+  CDMWrapper(PP_Instance instance, pp::Module* module);
+  virtual ~CDMWrapper() {}
+
+  // PPP_ContentDecryptor_Dev methods
+  virtual bool GenerateKeyRequest(PP_Var key_system, PP_Var init_data) OVERRIDE;
+  virtual bool AddKey(PP_Var session_id, PP_Var key) OVERRIDE;
+  virtual bool CancelKeyRequest(PP_Var session_id) OVERRIDE;
+  virtual bool Decrypt(PP_Resource encrypted_block,
+                       uint64_t request_id) OVERRIDE;
+
+  virtual bool DecryptAndDecode(PP_Resource encrypted_block,
+                                uint64_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_Dev</code> dispatchers. These are passed to
+  // <code>callback_factory_</code> to ensure that calls into
+  // <code>PPP_ContentDecryptor_Dev</code> are asynchronous.
+  void NeedKey(int32 result, const DecryptorMessage& decryptor_message);
+  void KeyAdded(int32 result, const DecryptorMessage& decryptor_message);
+  void KeyMessage(int32 result, const DecryptorMessage& decryptor_message);
+  void KeyError(int32 result, const DecryptorMessage& decryptor_message);
+  void DeliverBlock(int32 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 next_session_id_;

[dmichael (off chromium), 2012/08/08 22:24:02]

I would suggest using ppapi/c/pp_stdint.h and uint32_t, rather than including
base/basictypes.h

[Tom Finegan, 2012/08/09 22:45:17]

Done.

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

[dmichael (off chromium), 2012/08/08 22:24:02]

Or map to some delegate class that is set up to handle 1 session_id, so that
this top-level class can just be responsible for dispatching by session_id?

+  std::string key_;
+  std::string key_system_;
+};
+
+CDMWrapper::CDMWrapper(PP_Instance instance,
+                       pp::Module* module)
+    : pp::Instance(instance),
+      pp::ContentDecryptor_Dev(this),
+      next_session_id_(0) {
+  callback_factory_.Initialize(this);
+}
+
+bool CDMWrapper::GenerateKeyRequest(PP_Var key_system_arg,
+                                    PP_Var init_data_arg) {
+
+  pp::Var init_data(pp::PASS_REF, init_data_arg);
+
+  // TODO(tomfinegan): Testing only implementation; init data will not always
+  // be the key ID.
+  pp::Var key_system_var(pp::PASS_REF, key_system_arg);
+
+  // TODO(tomfinegan): confirm support for the key system.
+
+  DecryptorMessage decryptor_message;
+  key_system_ = key_system_var.AsString();
+  decryptor_message.key_system = key_system_;
+  session_id_ = base::UintToString(next_session_id_++);

[dmichael (off chromium), 2012/08/08 22:24:02]

I think it would be better to use a stringstream instead, than to rely on base.

[Tom Finegan, 2012/08/09 22:45:17]

Done.

+  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,

[dmichael (off chromium), 2012/08/08 22:24:02]

I don't know whether you want to rely on this...  but if you're always running
out-of-process (and you should :-) ), this stuff will all be asynchronous (since
you use asynchronous messages in the proxy). So you don't really need to post a
task.

+                                           decryptor_message));
+  return true;
+}
+
+bool CDMWrapper::AddKey(PP_Var session_id_var, PP_Var key_arg) {
+  pp::Var session_id(pp::PASS_REF, session_id_var);
+  if (!IsValidSessionId(session_id.AsString()))
+    return false;
+
+  pp::VarArrayBuffer key(pp::Var(pp::PASS_REF, key_arg));
+  if (!key.is_array_buffer())

[dmichael (off chromium), 2012/08/08 22:24:02]

you should always check is_array_buffer _before_ using the Var->VarArrayBuffer
constructor (the constructor asserts that it's an array buffer).

But...  this check should probably be happening in the C++ wrapper, in any case.

[Tom Finegan, 2012/08/09 22:45:17]

Done/checked in c++ wrapper.

+    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(PP_Var session_id_arg) {
+  pp::Var session_id_var(pp::PASS_REF, session_id_arg);
+
+  if (!IsValidSessionId(session_id_var.AsString()))
+    return false;
+
+  // TODO(tomfinegan): cancel pending key request in CDM.
+
+  return true;
+}
+
+bool CDMWrapper::Decrypt(PP_Resource encrypted_block,
+                         uint64_t request_id) {
+  pp::Buffer_Dev block_buffer(encrypted_block);
+  if (!block_buffer.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) {

[dmichael (off chromium), 2012/08/08 22:24:02]

I don't think a string is the best way to represent your binary data. I know
it's convenient right now since you're using c-strings to make easy dummy data,
but it's probably worth changing now to something more appropriate so you don't
get stuck down a hole.

[Tom Finegan, 2012/08/09 22:45:17]

Discussed offline.

+  if (str.empty())
+    return 0;
+
+  pp::Buffer_Dev buffer(this, str.size());
+  if (!buffer.data())
+    return 0;
+
+  memcpy(buffer.data(), str.data(), str.size());
+  return buffer.detach();
+}
+
+void CDMWrapper::NeedKey(int32 result,
+                         const DecryptorMessage& decryptor_message) {
+  pp::Var key_system(decryptor_message.key_system);
+  pp::Var session_id(decryptor_message.session_id);
+  pp::Var init_data(decryptor_message.message_data);
+  pp::ContentDecryptor_Dev::NeedKey(key_system.pp_var(),
+                                    session_id.pp_var(),
+                                    init_data.pp_var());
+}
+
+void CDMWrapper::KeyAdded(int32 result,
+                          const DecryptorMessage& decryptor_message) {
+  PP_Var key_system = pp::Var(decryptor_message.key_system).pp_var();
+  PP_Var session_id = pp::Var(decryptor_message.session_id).pp_var();
+  pp::ContentDecryptor_Dev::KeyAdded(key_system, session_id);
+}
+
+void CDMWrapper::KeyMessage(int32 result,
+                            const DecryptorMessage& decryptor_message) {
+  PP_Var key_system = pp::Var(decryptor_message.key_system).pp_var();
+  PP_Var session_id = pp::Var(decryptor_message.session_id).pp_var();
+  PP_Resource message =
+      StringToBufferResource(decryptor_message.message_data);
+  PP_Var default_url = pp::Var(decryptor_message.default_url).pp_var();
+  pp::ContentDecryptor_Dev::KeyMessage(key_system,
+                                       session_id,
+                                       message,
+                                       default_url);
+}
+
+void CDMWrapper::KeyError(int32 result,
+                          const DecryptorMessage& decryptor_message) {
+  PP_Var key_system = pp::Var(decryptor_message.key_system).pp_var();
+  PP_Var session_id = pp::Var(decryptor_message.session_id).pp_var();
+  pp::ContentDecryptor_Dev::KeyError(key_system,
+                                     session_id,
+                                     decryptor_message.media_error,
+                                     decryptor_message.system_error);
+}
+
+void CDMWrapper::DeliverBlock(int32 result,
+                              const DecryptedBlock& decrypted_block) {
+  PP_Resource decrypted_resource = StringToBufferResource(
+      decrypted_block.data);
+  if (decrypted_resource) {
+    pp::ContentDecryptor_Dev::DeliverBlock(decrypted_resource,
+                                           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