extensions/renderer/event_bindings.cc

   1 // Copyright 2014 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 "extensions/renderer/event_bindings.h"
   6
   7 #include <map>
   8 #include <utility>
   9
  10 #include "base/basictypes.h"
  11 #include "base/bind.h"
  12 #include "base/containers/scoped_ptr_map.h"
  13 #include "base/lazy_instance.h"
  14 #include "base/memory/scoped_ptr.h"
  15 #include "components/crx_file/id_util.h"
  16 #include "content/public/child/v8_value_converter.h"
  17 #include "content/public/renderer/render_frame.h"
  18 #include "content/public/renderer/render_thread.h"
  19 #include "content/public/renderer/render_view.h"
  20 #include "extensions/common/event_filter.h"
  21 #include "extensions/common/extension.h"
  22 #include "extensions/common/extension_messages.h"
  23 #include "extensions/common/value_counter.h"
  24 #include "extensions/renderer/extension_frame_helper.h"
  25 #include "extensions/renderer/script_context.h"
  26 #include "url/gurl.h"
  27
  28 namespace extensions {
  29
  30 namespace {
  31
  32 // A map of event names to the number of contexts listening to that event.
  33 // We notify the browser about event listeners when we transition between 0
  34 // and 1.
  35 typedef std::map<std::string, int> EventListenerCounts;
  36
  37 // A map of extension IDs to listener counts for that extension.
  38 base::LazyInstance<std::map<std::string, EventListenerCounts>>
  39     g_listener_counts = LAZY_INSTANCE_INITIALIZER;
  40
  41 // A map of (extension ID, event name) pairs to the filtered listener counts
  42 // for that pair. The map is used to keep track of which filters are in effect
  43 // for which events.  We notify the browser about filtered event listeners when
  44 // we transition between 0 and 1.
  45 using FilteredEventListenerKey = std::pair<std::string, std::string>;
  46 using FilteredEventListenerCounts =
  47     base::ScopedPtrMap<FilteredEventListenerKey, scoped_ptr<ValueCounter>>;
  48 base::LazyInstance<FilteredEventListenerCounts> g_filtered_listener_counts =
  49     LAZY_INSTANCE_INITIALIZER;
  50
  51 base::LazyInstance<EventFilter> g_event_filter = LAZY_INSTANCE_INITIALIZER;
  52
  53 // Gets a unique string key identifier for a ScriptContext.
  54 // TODO(kalman): Just use pointer equality...?
  55 std::string GetKeyForScriptContext(ScriptContext* script_context) {
  56   const std::string& extension_id = script_context->GetExtensionID();
  57   CHECK(crx_file::id_util::IdIsValid(extension_id) ||
  58         script_context->GetURL().is_valid());
  59   return crx_file::id_util::IdIsValid(extension_id)
  60              ? extension_id
  61              : script_context->GetURL().spec();
  62 }
  63
  64 // Increments the number of event-listeners for the given |event_name| and
  65 // ScriptContext. Returns the count after the increment.
  66 int IncrementEventListenerCount(ScriptContext* script_context,
  67                                 const std::string& event_name) {
  68   return ++g_listener_counts
  69                .Get()[GetKeyForScriptContext(script_context)][event_name];
  70 }
  71
  72 // Decrements the number of event-listeners for the given |event_name| and
  73 // ScriptContext. Returns the count after the increment.
  74 int DecrementEventListenerCount(ScriptContext* script_context,
  75                                 const std::string& event_name) {
  76   return --g_listener_counts
  77                .Get()[GetKeyForScriptContext(script_context)][event_name];
  78 }
  79
  80 EventFilteringInfo ParseFromObject(v8::Local<v8::Object> object,
  81                                    v8::Isolate* isolate) {
  82   EventFilteringInfo info;
  83   v8::Local<v8::String> url(v8::String::NewFromUtf8(isolate, "url"));
  84   if (object->Has(url)) {
  85     v8::Local<v8::Value> url_value(object->Get(url));
  86     info.SetURL(GURL(*v8::String::Utf8Value(url_value)));
  87   }
  88   v8::Local<v8::String> instance_id(
  89       v8::String::NewFromUtf8(isolate, "instanceId"));
  90   if (object->Has(instance_id)) {
  91     v8::Local<v8::Value> instance_id_value(object->Get(instance_id));
  92     info.SetInstanceID(instance_id_value->IntegerValue());
  93   }
  94   v8::Local<v8::String> service_type(
  95       v8::String::NewFromUtf8(isolate, "serviceType"));
  96   if (object->Has(service_type)) {
  97     v8::Local<v8::Value> service_type_value(object->Get(service_type));
  98     info.SetServiceType(*v8::String::Utf8Value(service_type_value));
  99   }
 100   return info;
 101 }
 102
 103 // Add a filter to |event_name| in |extension_id|, returning true if it
 104 // was the first filter for that event in that extension.
 105 bool AddFilter(const std::string& event_name,
 106                const std::string& extension_id,
 107                const base::DictionaryValue& filter) {
 108   FilteredEventListenerKey key(extension_id, event_name);
 109   FilteredEventListenerCounts& all_counts = g_filtered_listener_counts.Get();
 110   FilteredEventListenerCounts::const_iterator counts = all_counts.find(key);
 111   if (counts == all_counts.end()) {
 112     counts = all_counts.insert(key, make_scoped_ptr(new ValueCounter())).first;
 113   }
 114   return counts->second->Add(filter);
 115 }
 116
 117 // Remove a filter from |event_name| in |extension_id|, returning true if it
 118 // was the last filter for that event in that extension.
 119 bool RemoveFilter(const std::string& event_name,
 120                   const std::string& extension_id,
 121                   base::DictionaryValue* filter) {
 122   FilteredEventListenerKey key(extension_id, event_name);
 123   FilteredEventListenerCounts& all_counts = g_filtered_listener_counts.Get();
 124   FilteredEventListenerCounts::const_iterator counts = all_counts.find(key);
 125   if (counts == all_counts.end())
 126     return false;
 127   // Note: Remove() returns true if it removed the last filter equivalent to
 128   // |filter|. If there are more equivalent filters, or if there weren't any in
 129   // the first place, it returns false.
 130   if (counts->second->Remove(*filter)) {
 131     if (counts->second->is_empty())
 132       all_counts.erase(counts);  // Clean up if there are no more filters.
 133     return true;
 134   }
 135   return false;
 136 }
 137
 138 }  // namespace
 139
 140 EventBindings::EventBindings(ScriptContext* context)
 141     : ObjectBackedNativeHandler(context) {
 142   RouteFunction("AttachEvent", base::Bind(&EventBindings::AttachEventHandler,
 143                                           base::Unretained(this)));
 144   RouteFunction("DetachEvent", base::Bind(&EventBindings::DetachEventHandler,
 145                                           base::Unretained(this)));
 146   RouteFunction(
 147       "AttachFilteredEvent",
 148       base::Bind(&EventBindings::AttachFilteredEvent, base::Unretained(this)));
 149   RouteFunction("DetachFilteredEvent",
 150                 base::Bind(&EventBindings::DetachFilteredEventHandler,
 151                            base::Unretained(this)));
 152   RouteFunction("MatchAgainstEventFilter",
 153                 base::Bind(&EventBindings::MatchAgainstEventFilter,
 154                            base::Unretained(this)));
 155
 156   // It's safe to use base::Unretained here because |context| will always
 157   // outlive us.
 158   context->AddInvalidationObserver(
 159       base::Bind(&EventBindings::OnInvalidated, base::Unretained(this)));
 160 }
 161
 162 EventBindings::~EventBindings() {}
 163
 164 void EventBindings::AttachEventHandler(
 165     const v8::FunctionCallbackInfo<v8::Value>& args) {
 166   CHECK_EQ(1, args.Length());
 167   CHECK(args[0]->IsString());
 168   AttachEvent(*v8::String::Utf8Value(args[0]));
 169 }
 170
 171 void EventBindings::AttachEvent(const std::string& event_name) {
 172   if (!context()->HasAccessOrThrowError(event_name))
 173     return;
 174
 175   // Record the attachment for this context so that events can be detached when
 176   // the context is destroyed.
 177   //
 178   // Ideally we'd CHECK that it's not already attached, however that's not
 179   // possible because extensions can create and attach events themselves. Very
 180   // silly, but that's the way it is. For an example of this, see
 181   // chrome/test/data/extensions/api_test/events/background.js.
 182   attached_event_names_.insert(event_name);
 183
 184   const std::string& extension_id = context()->GetExtensionID();
 185   if (IncrementEventListenerCount(context(), event_name) == 1) {
 186     content::RenderThread::Get()->Send(new ExtensionHostMsg_AddListener(
 187         extension_id, context()->GetURL(), event_name));
 188   }
 189
 190   // This is called the first time the page has added a listener. Since
 191   // the background page is the only lazy page, we know this is the first
 192   // time this listener has been registered.
 193   if (ExtensionFrameHelper::IsContextForEventPage(context())) {
 194     content::RenderThread::Get()->Send(
 195         new ExtensionHostMsg_AddLazyListener(extension_id, event_name));
 196   }
 197 }
 198
 199 void EventBindings::DetachEventHandler(
 200     const v8::FunctionCallbackInfo<v8::Value>& args) {
 201   CHECK_EQ(2, args.Length());
 202   CHECK(args[0]->IsString());
 203   CHECK(args[1]->IsBoolean());
 204   DetachEvent(*v8::String::Utf8Value(args[0]), args[1]->BooleanValue());
 205 }
 206
 207 void EventBindings::DetachEvent(const std::string& event_name, bool is_manual) {
 208   // See comment in AttachEvent().
 209   attached_event_names_.erase(event_name);
 210
 211   const std::string& extension_id = context()->GetExtensionID();
 212
 213   if (DecrementEventListenerCount(context(), event_name) == 0) {
 214     content::RenderThread::Get()->Send(new ExtensionHostMsg_RemoveListener(
 215         extension_id, context()->GetURL(), event_name));
 216   }
 217
 218   // DetachEvent is called when the last listener for the context is
 219   // removed. If the context is the background page, and it removes the
 220   // last listener manually, then we assume that it is no longer interested
 221   // in being awakened for this event.
 222   if (is_manual && ExtensionFrameHelper::IsContextForEventPage(context())) {
 223     content::RenderThread::Get()->Send(
 224         new ExtensionHostMsg_RemoveLazyListener(extension_id, event_name));
 225   }
 226 }
 227
 228 // MatcherID AttachFilteredEvent(string event_name, object filter)
 229 // event_name - Name of the event to attach.
 230 // filter - Which instances of the named event are we interested in.
 231 // returns the id assigned to the listener, which will be returned from calls
 232 // to MatchAgainstEventFilter where this listener matches.
 233 void EventBindings::AttachFilteredEvent(
 234     const v8::FunctionCallbackInfo<v8::Value>& args) {
 235   CHECK_EQ(2, args.Length());
 236   CHECK(args[0]->IsString());
 237   CHECK(args[1]->IsObject());
 238
 239   std::string event_name = *v8::String::Utf8Value(args[0]);
 240   if (!context()->HasAccessOrThrowError(event_name))
 241     return;
 242
 243   scoped_ptr<base::DictionaryValue> filter;
 244   {
 245     scoped_ptr<content::V8ValueConverter> converter(
 246         content::V8ValueConverter::create());
 247     scoped_ptr<base::Value> filter_value(converter->FromV8Value(
 248         v8::Local<v8::Object>::Cast(args[1]), context()->v8_context()));
 249     if (!filter_value || !filter_value->IsType(base::Value::TYPE_DICTIONARY)) {
 250       args.GetReturnValue().Set(static_cast<int32_t>(-1));
 251       return;
 252     }
 253     filter.reset(static_cast<base::DictionaryValue*>(filter_value.release()));
 254   }
 255
 256   // Hold onto a weak reference to |filter| so that it can be used after passing
 257   // ownership to |event_filter|.
 258   base::DictionaryValue* filter_weak = filter.get();
 259   int id = g_event_filter.Get().AddEventMatcher(
 260       event_name, ParseEventMatcher(filter.Pass()));
 261   attached_matcher_ids_.insert(id);
 262
 263   // Only send IPCs the first time a filter gets added.
 264   std::string extension_id = context()->GetExtensionID();
 265   if (AddFilter(event_name, extension_id, *filter_weak)) {
 266     bool lazy = ExtensionFrameHelper::IsContextForEventPage(context());
 267     content::RenderThread::Get()->Send(new ExtensionHostMsg_AddFilteredListener(
 268         extension_id, event_name, *filter_weak, lazy));
 269   }
 270
 271   args.GetReturnValue().Set(static_cast<int32_t>(id));
 272 }
 273
 274 void EventBindings::DetachFilteredEventHandler(
 275     const v8::FunctionCallbackInfo<v8::Value>& args) {
 276   CHECK_EQ(2, args.Length());
 277   CHECK(args[0]->IsInt32());
 278   CHECK(args[1]->IsBoolean());
 279   DetachFilteredEvent(args[0]->Int32Value(), args[1]->BooleanValue());
 280 }
 281
 282 void EventBindings::DetachFilteredEvent(int matcher_id, bool is_manual) {
 283   EventFilter& event_filter = g_event_filter.Get();
 284   EventMatcher* event_matcher = event_filter.GetEventMatcher(matcher_id);
 285
 286   const std::string& event_name = event_filter.GetEventName(matcher_id);
 287
 288   // Only send IPCs the last time a filter gets removed.
 289   std::string extension_id = context()->GetExtensionID();
 290   if (RemoveFilter(event_name, extension_id, event_matcher->value())) {
 291     bool remove_lazy =
 292         is_manual && ExtensionFrameHelper::IsContextForEventPage(context());
 293     content::RenderThread::Get()->Send(
 294         new ExtensionHostMsg_RemoveFilteredListener(
 295             extension_id, event_name, *event_matcher->value(), remove_lazy));
 296   }
 297
 298   event_filter.RemoveEventMatcher(matcher_id);
 299   attached_matcher_ids_.erase(matcher_id);
 300 }
 301
 302 void EventBindings::MatchAgainstEventFilter(
 303     const v8::FunctionCallbackInfo<v8::Value>& args) {
 304   v8::Isolate* isolate = args.GetIsolate();
 305   typedef std::set<EventFilter::MatcherID> MatcherIDs;
 306   EventFilter& event_filter = g_event_filter.Get();
 307   std::string event_name = *v8::String::Utf8Value(args[0]);
 308   EventFilteringInfo info =
 309       ParseFromObject(args[1]->ToObject(isolate), isolate);
 310   // Only match events routed to this context's RenderFrame or ones that don't
 311   // have a routingId in their filter.
 312   MatcherIDs matched_event_filters = event_filter.MatchEvent(
 313       event_name, info, context()->GetRenderFrame()->GetRoutingID());
 314   v8::Local<v8::Array> array(
 315       v8::Array::New(isolate, matched_event_filters.size()));
 316   int i = 0;
 317   for (MatcherIDs::iterator it = matched_event_filters.begin();
 318        it != matched_event_filters.end();
 319        ++it) {
 320     array->Set(v8::Integer::New(isolate, i++), v8::Integer::New(isolate, *it));
 321   }
 322   args.GetReturnValue().Set(array);
 323 }
 324
 325 scoped_ptr<EventMatcher> EventBindings::ParseEventMatcher(
 326     scoped_ptr<base::DictionaryValue> filter) {
 327   return make_scoped_ptr(new EventMatcher(
 328       filter.Pass(), context()->GetRenderFrame()->GetRoutingID()));
 329 }
 330
 331 void EventBindings::OnInvalidated() {
 332   // Detach all attached events that weren't attached. Iterate over a copy
 333   // because it will be mutated.
 334   std::set<std::string> attached_event_names_safe = attached_event_names_;
 335   for (const std::string& event_name : attached_event_names_safe) {
 336     DetachEvent(event_name, false /* is_manual */);
 337   }
 338   DCHECK(attached_event_names_.empty())
 339       << "Events cannot be attached during invalidation";
 340
 341   // Same for filtered events.
 342   std::set<int> attached_matcher_ids_safe = attached_matcher_ids_;
 343   for (int matcher_id : attached_matcher_ids_safe) {
 344     DetachFilteredEvent(matcher_id, false /* is_manual */);
 345   }
 346   DCHECK(attached_matcher_ids_.empty())
 347       << "Filtered events cannot be attached during invalidation";
 348 }
 349
 350 }  // namespace extensions