Add PPAPI decryptor interfaces.

ppapi/examples/content_decryptor/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 <string>
+
+#include "base/basictypes.h"
+#include "ppapi/c/pp_var.h"
+#include "ppapi/c/ppb_var.h"
+#include "ppapi/c/dev/ppb_buffer_dev.h"
+#include "ppapi/c/dev/ppb_console_dev.h"
+#include "ppapi/c/dev/ppb_content_decryptor_dev.h"
+#include "ppapi/cpp/core.h"
+#include "ppapi/cpp/instance.h"
+#include "ppapi/cpp/module.h"
+#include "ppapi/cpp/resource.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 {
+  PP_Var key_system;
+  PP_Var session_id;
+  PP_Var default_url;
+  PP_Resource message_data;
+  uint16 media_error;
+  uint16 system_error;
+};
+
+// Helper function for obtaining a std::string given a PP_Var of type
+// PP_VARTYPE_STRING. Returns an empty string when things go wrong, or the
+// contents of the PP_Var (which could also be empty).
+std::string VarToString(const PPB_Var* var_if, const PP_Var* var) {
+  std::string var_string;
+
+  if (var_if && var && var->type == PP_VARTYPE_STRING) {
+    // Extract the key system string from |key_system_arg|. The extracted
+    // string is NOT NULL TERMINATED.
+    uint32_t length = 0;
+    const char* p_var_string = var_if->VarToUtf8(*var, &length);
+
+    if (p_var_string && length)
+      var_string.assign(p_var_string, length);
+  }
+
+  return var_string;
+}
+
+// Creates PP_Var from |str| using |var_if|, AddRef's it, and returns the
+// PP_Var. Returns empty var when |var_if| is NULL, or when |str| is empty.
+PP_Var StringToVar(const PPB_Var* var_if, const std::string& str) {
+  if (!var_if || str.empty())
+    return PP_MakeNull();
+
+  PP_Var var = var_if->VarFromUtf8(str.c_str(), str.length());
+  var_if->AddRef(var);
+  return var;
+}
+
+}  // 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:
+  explicit CDMWrapper(PP_Instance instance, pp::Module* module);
+  virtual ~CDMWrapper() {}
+
+  // PPP_ContentDecryptor_Dev methods
+  virtual bool GenerateKeyRequest(PP_Var key_system,
+                                  PP_Resource init_data);
+
+  virtual bool AddKey(PP_Var session_id,
+                      PP_Resource key) {
+    return false;
+  }
+
+  virtual bool CancelKeyRequest(PP_Var session_id) {
+    return false;
+  }
+
+  virtual bool Decrypt(PP_Resource encrypted_block,
+                       PP_CompletionCallback callback);
+
+  virtual bool DecryptAndDecode(PP_Resource encrypted_block,
+                                PP_CompletionCallback callback) {
+    return false;
+  }
+
+  virtual bool Init(uint32_t argc, const char* argn[], const char* argv[]) {
+    return true;
+  }
+
+ private:
+   PP_Resource StringToBufferResource(const std::string& str);
+   void DispatchKeyMessage(int32 result, void* data);
+
+   // Browser interfaces.
+   const PPB_Buffer_Dev* buffer_if_;
+   const PPB_Console_Dev* console_if_;
+   const PPB_ContentDecryptor_Dev* cdm_if_;
+   const PPB_Var* var_if_;
+
+   pp::CompletionCallbackFactory<CDMWrapper> factory_;
+};
+
+// 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);
+  }
+};
+
+CDMWrapper::CDMWrapper(PP_Instance instance,
+                       pp::Module* module)
+    : pp::Instance(instance),
+      pp::ContentDecryptor_Dev(this) {
+  console_if_ = static_cast<const PPB_Console_Dev*>(
+      module->GetBrowserInterface(PPB_CONSOLE_DEV_INTERFACE));
+  assert(console_if_);
+  cdm_if_ = static_cast<const PPB_ContentDecryptor_Dev*>(
+      module->GetBrowserInterface(PPB_CONTENTDECRYPTOR_DEV_INTERFACE));
+  assert(cdm_if_);
+  buffer_if_ = static_cast<const PPB_Buffer_Dev*>(
+      module->GetBrowserInterface(PPB_BUFFER_DEV_INTERFACE));
+  assert(buffer_if_);
+  var_if_ = static_cast<const PPB_Var*>(
+      module->GetBrowserInterface(PPB_VAR_INTERFACE));
+  assert(var_if_);
+  factory_.Initialize(this);
+}
+
+bool CDMWrapper::GenerateKeyRequest(PP_Var key_system_arg,
+                                    PP_Resource init_data) {
+  std::string key_system = VarToString(var_if_, &key_system_arg);
+  if (key_system.empty())
+    return false;
+
+  if (init_data) {
+    pp::Buffer_Dev init_buffer(init_data);
+    if (!buffer_if_->IsBuffer(init_buffer.pp_resource()) ||
+        !init_buffer.data()) {
+      return false;
+    }
+  }
+
+  // TODO(tomfinegan): this is a testing hack, remove.
+  const std::string message = "key request";
+  PP_Resource message_resource = StringToBufferResource(message);
+
+  if (!message_resource)
+    return false;
+
+  const std::string session_id = "12345";
+  PP_Var session_id_var = StringToVar(var_if_, session_id);
+
+  const std::string default_url = "http://www.google.com";
+  PP_Var default_url_var = StringToVar(var_if_, default_url);
+
+  if (!pp::Module::Get()->core()->IsMainThread()) {

[ddorwin, 2012/07/18 21:48:36]

As this function is written, this statement will never be true. Also, we always
want the response to be async (I'm pretty sure), so we should just always do
this. Long term, it will come from the wrapped CDM, which should have the same
behavior.

[Tom Finegan, 2012/07/23 18:41:53]

Done.

+    DecryptorMessage* dm = new (std::nothrow) DecryptorMessage;

[ddorwin, 2012/07/18 21:48:36]

s/dm/message/

[ddorwin, 2012/07/18 21:48:36]

Why nothrow? We're not checking the pointer. I think we just crash on OOM.

[Tom Finegan, 2012/07/23 18:41:53]

Removed the nothrow.

[Tom Finegan, 2012/07/23 18:41:53]

Renamed to decryptor_message (because I already have a message).

+    dm->key_system = key_system_arg;
+    dm->session_id = session_id_var;
+    dm->default_url = default_url_var;
+    dm->message_data = message_resource;
+    void* data = reinterpret_cast<void*>(&dm);
+
+    pp::Module::Get()->core()->CallOnMainThread(
+        0, factory_.NewCallback(&CDMWrapper::DispatchKeyMessage, data), 0);

[ddorwin, 2012/07/18 21:48:36]

data will be leaked if the callback is not called (i.e. this object is
destroyed).
xhwang pointed out that the examples pass by value/reference:
http://code.google.com/searchframe#OAMlx_jo-ck/src/ppapi/utility/completion_c...

[Tom Finegan, 2012/07/23 18:41:53]

Ah-- I'll update to pass by value in the next pass. Forgot to double check
comments before the upload just now.

+  } else {
+    cdm_if_->KeyMessage(pp_instance(), key_system_arg, session_id_var,
+                        message_resource, default_url_var);
+  }
+
+  return true;
+}
+
+bool CDMWrapper::Decrypt(PP_Resource encrypted_block,
+                         PP_CompletionCallback callback) {
+  pp::Buffer_Dev block_buffer(encrypted_block);
+  if (!buffer_if_->IsBuffer(block_buffer.pp_resource()) ||
+      !block_buffer.data()) {
+    return false;
+  }
+
+  const std::string kDummyDecryptedData = "Pretend I'm decrypted data!";
+  PP_Resource decrypted_resource = StringToBufferResource(kDummyDecryptedData);
+  if (!decrypted_resource)
+    return false;
+
+  cdm_if_->DeliverBlock(pp_instance(), decrypted_resource, callback);
+  return true;
+}
+
+PP_Resource CDMWrapper::StringToBufferResource(const std::string& str) {
+  if (!str.size())
+    return 0;
+
+  pp::Buffer_Dev buffer(this, str.size());
+  if (!buffer_if_->IsBuffer(buffer.pp_resource()) || !buffer.data())
+    return 0;
+
+  memcpy(buffer.data(), str.data(), str.size());
+  return buffer.detach();
+}
+
+void CDMWrapper::DispatchKeyMessage(int32 result, void* data) {
+  DecryptorMessage* message = reinterpret_cast<DecryptorMessage*>(data);

[ddorwin, 2012/07/18 21:48:36]

This should be moot based on above, but I would just put this in a scoped_ptr
and eliminate 224.

[Tom Finegan, 2012/07/23 18:41:53]

Done.

+  if (message) {
+    cdm_if_->KeyMessage(pp_instance(),
+                        message->key_system,
+                        message->session_id,
+                        message->message_data,
+                        message->default_url);
+    delete data;
+  }
+}
+
+namespace pp {
+
+// Factory function for your specialization of the Module object.
+Module* CreateModule() {
+  return new MyModule();
+}
+
+}  // namespace pp