Browser Plugin: New Implementation (Renderer Side)

content/renderer/browser_plugin/browser_plugin_bindings.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 "content/renderer/browser_plugin/browser_plugin_bindings.h"
+
+#include <cstdlib>
+#include <string>
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "base/message_loop.h"
+#include "base/string16.h"
+#include "base/string_split.h"
+#include "base/utf_string_conversions.h"
+#include "content/renderer/browser_plugin/browser_plugin.h"
+#include "third_party/npapi/bindings/npapi.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebBindings.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebDocument.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebDOMMessageEvent.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebElement.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebFrame.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebNode.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebPluginContainer.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebSerializedScriptValue.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebString.h"
+#include "v8/include/v8.h"
+
+using WebKit::WebBindings;
+using WebKit::WebElement;
+using WebKit::WebDOMEvent;
+using WebKit::WebDOMMessageEvent;
+using WebKit::WebPluginContainer;
+using WebKit::WebSerializedScriptValue;
+using WebKit::WebString;
+
+namespace content {
+
+namespace browser_plugin {
+
+namespace {
+
+const char kAddEventListener[] = "addEventListener";
+const char kRemoveEventListener[] = "removeEventListener";
+const char kPostMessage[] = "postMessage";
+const char kSrcAttribute[] = "src";
+
+BrowserPluginBindings* GetBindings(NPObject* object) {
+  return static_cast<BrowserPluginBindings::BrowserPluginNPObject*>(object)->
+      message_channel;
+}
+
+bool IdentifierIsAddEventListener(NPIdentifier identifier) {
+  return WebBindings::getStringIdentifier(kAddEventListener) == identifier;
+}
+
+bool IdentifierIsRemoveEventListener(NPIdentifier identifier) {
+  return WebBindings::getStringIdentifier(kRemoveEventListener) == identifier;
+}
+
+bool IdentifierIsPostMessage(NPIdentifier identifier) {
+  return WebBindings::getStringIdentifier(kPostMessage) == identifier;
+}
+
+bool IdentifierIsSrcAttribute(NPIdentifier identifier) {
+  return WebBindings::getStringIdentifier(kSrcAttribute) == identifier;
+}
+
+std::string StringFromNPVariant(const NPVariant& variant) {
+  if (!NPVARIANT_IS_STRING(variant))
+    return std::string();
+  const NPString& np_string = NPVARIANT_TO_STRING(variant);
+  return std::string(np_string.UTF8Characters, np_string.UTF8Length);
+}
+
+string16 String16FromNPVariant(const NPVariant& variant) {
+  if (!NPVARIANT_IS_STRING(variant))
+    return string16();
+  const NPString& np_string = NPVARIANT_TO_STRING(variant);
+  string16 wstr;
+  if (!UTF8ToUTF16(np_string.UTF8Characters, np_string.UTF8Length, &wstr))
+    return string16();
+  return wstr;
+}
+
+bool StringToNPVariant(const std::string &in, NPVariant *variant) {
+  size_t length = in.size();
+  NPUTF8 *chars = static_cast<NPUTF8 *>(malloc(length));
+  if (!chars) {
+    VOID_TO_NPVARIANT(*variant);
+    return false;
+  }
+  memcpy(chars, in.c_str(), length);
+  STRINGN_TO_NPVARIANT(chars, length, *variant);
+  return true;
+}
+
+//------------------------------------------------------------------------------
+// Implementations of NPClass functions.  These are here to:
+// - Implement postMessage behavior.
+// - Implement src attribute.
+//------------------------------------------------------------------------------
+NPObject* BrowserPluginBindingsAllocate(NPP npp, NPClass* the_class) {
+  return new BrowserPluginBindings::BrowserPluginNPObject;
+}
+
+void BrowserPluginBindingsDeallocate(NPObject* object) {
+  BrowserPluginBindings::BrowserPluginNPObject* instance =
+      static_cast<BrowserPluginBindings::BrowserPluginNPObject*>(object);
+  delete instance;
+}
+
+bool BrowserPluginBindingsHasMethod(NPObject* np_obj, NPIdentifier name) {
+  if (!np_obj)
+    return false;
+
+  if (IdentifierIsPostMessage(name))
+    return true;
+
+  if (IdentifierIsAddEventListener(name))
+    return true;
+
+  if (IdentifierIsRemoveEventListener(name))
+    return true;
+
+  return false;
+}
+
+bool BrowserPluginBindingsInvoke(NPObject* np_obj, NPIdentifier name,
+                                 const NPVariant* args, uint32 arg_count,
+                                 NPVariant* result) {
+  if (!np_obj)
+    return false;
+
+  BrowserPluginBindings* bindings = GetBindings(np_obj);
+  if (!bindings)
+    return false;
+
+  if (IdentifierIsPostMessage(name) && (arg_count == 2)) {

[Charlie Reis, 2012/08/03 18:06:02]

Is this a typical pattern for bindings classes, or do we usually break it into
helper functions?  This Invoke function could grow quite large if we add more
handled identifiers.  (Not a big problem right now, I suppose.)

[Fady Samuel, 2012/08/03 19:34:43]

I agree, this will grow long fairly quickly as the API gets richer. I promise to
clean it up...in a separate patch, when we start adding an error API :-)

+    v8::Handle<v8::Value> v8_val = WebBindings::toV8Value(&args[0]);
+    // If serialization fails, there may be a V8 exception pending.
+    // Don't touch the V8 state (eg, to raise our own 'error calling
+    // method on NPObject' exception).
+    if (v8_val.IsEmpty())
+      // This might happen if toV8Value fails an allocation.
+      // Does SafeAllocation::newInstance throw an exception in this case?
+      return true;
+    WebSerializedScriptValue serialized_v8_val =
+        WebSerializedScriptValue::serialize(v8_val);
+    WebString message_string = serialized_v8_val.toString();
+    // Serialization can sometimes fail (the user might try to fax the
+    // |window|, for example); ::serialize will result in a
+    // DATA_CLONE_ERR being raised, but we still need to abort
+    // the postMessage() operation. There's no clear way to test
+    // for failure in WebSerializedScriptValue, but an empty string
+    // should signal an invalid object. (The serializer at a nonzero
+    // version will always write a version tag.)
+    // v8::TryCatch, for some reason, was not catching DATA_CLONE_ERR;
+    // if this worked, it would be the right way to go.
+    // (This isn't the only way that serialization might fail! Other
+    // exceptions are possible.)
+    if (!message_string.length())
+      return true;
+    string16 message(message_string);
+    string16 target_origin = String16FromNPVariant(args[1]);
+    bindings->instance()->PostMessage(message, target_origin);

[Charlie Reis, 2012/08/03 18:06:02]

Just to confirm my understanding, this allows JS code in the embedder to post a
message to the guest, by routing it through the BrowserPlugin class and then via
the browser process, right?

[Fady Samuel, 2012/08/03 19:34:43]

That is correct.

+    return true;
+  }
+
+  if (IdentifierIsAddEventListener(name) && (arg_count == 2)) {
+    std::string event_name = StringFromNPVariant(args[0]);
+    if (event_name.empty())
+      return false;
+
+    v8::Local<v8::Value> value =
+        v8::Local<v8::Value>::New(WebBindings::toV8Value(&args[1]));
+    if (value.IsEmpty() || !value->IsFunction())
+      return false;
+
+    v8::Local<v8::Function> function = v8::Local<v8::Function>::Cast(value);
+    return bindings->instance()->AddEventListener(event_name, function);
+  }
+
+  if (IdentifierIsRemoveEventListener(name) && arg_count == 2) {
+    std::string event_name = StringFromNPVariant(args[0]);
+    if (event_name.empty())
+      return false;
+
+    v8::Local<v8::Value> value =
+        v8::Local<v8::Value>::New(WebBindings::toV8Value(&args[1]));
+
+    if (value.IsEmpty() || !value->IsFunction())
+      return false;
+
+    v8::Local<v8::Function> function = v8::Local<v8::Function>::Cast(value);
+    return bindings->instance()->RemoveEventListener(event_name, function);
+  }
+
+  return false;
+}
+
+bool BrowserPluginBindingsInvokeDefault(NPObject* np_obj,
+                                        const NPVariant* args,
+                                        uint32 arg_count,
+                                        NPVariant* result) {
+  NOTIMPLEMENTED();
+  return false;
+}
+
+bool BrowserPluginBindingsHasProperty(NPObject* np_obj, NPIdentifier name) {
+  return IdentifierIsSrcAttribute(name);
+}
+
+bool BrowserPluginBindingsGetProperty(NPObject* np_obj, NPIdentifier name,
+                                      NPVariant* result) {
+  if (!np_obj)
+    return false;
+
+  if (IdentifierIsPostMessage(name) ||
+      IdentifierIsAddEventListener(name) ||
+      IdentifierIsRemoveEventListener(name))
+    return false;
+
+  if (IdentifierIsSrcAttribute(name)) {
+    BrowserPluginBindings* bindings = GetBindings(np_obj);
+    if (!bindings)
+      return false;
+    std::string src = bindings->instance()->GetSrcAttribute();
+    return StringToNPVariant(src, result);
+  }
+
+  return false;
+}
+
+bool BrowserPluginBindingsSetProperty(NPObject* np_obj, NPIdentifier name,
+                                      const NPVariant* variant) {
+  if (!np_obj)
+    return false;
+
+  if (IdentifierIsSrcAttribute(name)) {
+    std::string src = StringFromNPVariant(*variant);
+    BrowserPluginBindings* bindings = GetBindings(np_obj);
+    if (!bindings)
+      return false;
+    bindings->instance()->SetSrcAttribute(src);
+    return true;
+  }
+  return false;
+}
+
+bool BrowserPluginBindingsEnumerate(NPObject *np_obj, NPIdentifier **value,
+                                    uint32_t *count) {
+  NOTIMPLEMENTED();
+  return true;
+}
+
+NPClass browser_plugin_message_class = {
+  NP_CLASS_STRUCT_VERSION,
+  &BrowserPluginBindingsAllocate,
+  &BrowserPluginBindingsDeallocate,
+  NULL,
+  &BrowserPluginBindingsHasMethod,
+  &BrowserPluginBindingsInvoke,
+  &BrowserPluginBindingsInvokeDefault,
+  &BrowserPluginBindingsHasProperty,
+  &BrowserPluginBindingsGetProperty,
+  &BrowserPluginBindingsSetProperty,
+  NULL,
+  &BrowserPluginBindingsEnumerate,
+};
+
+}  // namespace
+
+// BrowserPluginBindings ------------------------------------------------------
+
+BrowserPluginBindings::BrowserPluginNPObject::BrowserPluginNPObject() {
+}
+
+BrowserPluginBindings::BrowserPluginNPObject::~BrowserPluginNPObject() {
+}
+
+BrowserPluginBindings::BrowserPluginBindings(BrowserPlugin* instance)
+    : instance_(instance),
+      np_object_(NULL),
+      ALLOW_THIS_IN_INITIALIZER_LIST(weak_ptr_factory_(this)) {
+  NPObject* obj =
+      WebBindings::createObject(NULL, &browser_plugin_message_class);
+  np_object_ = static_cast<BrowserPluginBindings::BrowserPluginNPObject*>(obj);
+  np_object_->message_channel = weak_ptr_factory_.GetWeakPtr();
+}
+
+BrowserPluginBindings::~BrowserPluginBindings() {
+  WebBindings::releaseObject(np_object_);
+}
+
+}  // namespace browser_plugin
+}  // namespace content