LibWeb: Implement EventSource for server-sent events

EventSource allows opening a persistent HTTP connection to a server over which events are continuously streamed. Unfortunately, our test infrastructure does not allow for automating any tests of this feature yet. It only works with HTTP connections.
SerenityOS · May 26, 2024 · 260ffe6 · 260ffe6
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Showing 12 changed files with 619 additions and 1 deletion.
diff --git a/Meta/gn/secondary/Userland/Libraries/LibWeb/HTML/BUILD.gn b/Meta/gn/secondary/Userland/Libraries/LibWeb/HTML/BUILD.gn
@@ -31,6 +31,7 @@ source_set("HTML") {
     "ErrorEvent.cpp",
     "EventHandler.cpp",
     "EventNames.cpp",
+    "EventSource.cpp",
     "FileFilter.cpp",
     "Focus.cpp",
     "FormAssociatedElement.cpp",

diff --git a/Meta/gn/secondary/Userland/Libraries/LibWeb/idl_files.gni b/Meta/gn/secondary/Userland/Libraries/LibWeb/idl_files.gni
@@ -119,6 +119,7 @@ standard_idl_files = [
   "//Userland/Libraries/LibWeb/HTML/DOMParser.idl",
   "//Userland/Libraries/LibWeb/HTML/DOMStringMap.idl",
   "//Userland/Libraries/LibWeb/HTML/ErrorEvent.idl",
+  "//Userland/Libraries/LibWeb/HTML/EventSource.idl",
   "//Userland/Libraries/LibWeb/HTML/FormDataEvent.idl",
   "//Userland/Libraries/LibWeb/HTML/HashChangeEvent.idl",
   "//Userland/Libraries/LibWeb/HTML/History.idl",

diff --git a/Userland/Libraries/LibWeb/CMakeLists.txt b/Userland/Libraries/LibWeb/CMakeLists.txt
@@ -272,6 +272,7 @@ set(SOURCES
     HTML/DataTransfer.cpp
     HTML/ErrorEvent.cpp
     HTML/EventHandler.cpp
+    HTML/EventSource.cpp
     HTML/EventLoop/EventLoop.cpp
     HTML/EventLoop/Task.cpp
     HTML/EventLoop/TaskQueue.cpp

diff --git a/Userland/Libraries/LibWeb/DOM/Document.cpp b/Userland/Libraries/LibWeb/DOM/Document.cpp
@@ -3118,7 +3118,8 @@ void Document::run_unloading_cleanup_steps()
 
     // 4. If document's salvageable state is false, then:
     if (!m_salvageable) {
-        // FIXME: 1. For each EventSource object eventSource whose relevant global object is equal to window, forcibly close eventSource.
+        // 1. For each EventSource object eventSource whose relevant global object is equal to window, forcibly close eventSource.
+        window->forcibly_close_all_event_sources();
 
         // 2. Clear window's map of active timers.
         window->clear_map_of_active_timers();

diff --git a/Userland/Libraries/LibWeb/Forward.h b/Userland/Libraries/LibWeb/Forward.h
@@ -350,6 +350,7 @@ class DOMStringMap;
 class ErrorEvent;
 class EventHandler;
 class EventLoop;
+class EventSource;
 class FormAssociatedElement;
 class FormDataEvent;
 class History;

diff --git a/Userland/Libraries/LibWeb/HTML/EventLoop/Task.h b/Userland/Libraries/LibWeb/HTML/EventLoop/Task.h
@@ -57,6 +57,9 @@ class Task final : public JS::Cell {
         // https://drafts.csswg.org/css-font-loading/#task-source
         FontLoading,
 
+        // https://html.spec.whatwg.org/multipage/server-sent-events.html#remote-event-task-source
+        RemoteEvent,
+
         // !!! IMPORTANT: Keep this field last!
         // This serves as the base value of all unique task sources.
         // Some elements, such as the HTMLMediaElement, must have a unique task source per instance.

diff --git a/Userland/Libraries/LibWeb/HTML/EventSource.cpp b/Userland/Libraries/LibWeb/HTML/EventSource.cpp
diff --git a/Userland/Libraries/LibWeb/HTML/EventSource.h b/Userland/Libraries/LibWeb/HTML/EventSource.h
@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2024, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/String.h>
+#include <AK/StringBuilder.h>
+#include <AK/StringView.h>
+#include <AK/Time.h>
+#include <LibJS/Forward.h>
+#include <LibJS/Heap/GCPtr.h>
+#include <LibURL/URL.h>
+#include <LibWeb/DOM/EventTarget.h>
+#include <LibWeb/Forward.h>
+#include <LibWeb/WebIDL/ExceptionOr.h>
+#include <LibWeb/WebIDL/Types.h>
+
+namespace Web::HTML {
+
+struct EventSourceInit {
+    bool with_credentials { false };
+};
+
+class EventSource : public DOM::EventTarget {
+    WEB_PLATFORM_OBJECT(EventSource, DOM::EventTarget);
+    JS_DECLARE_ALLOCATOR(EventSource);
+
+public:
+    virtual ~EventSource() override;
+
+    static WebIDL::ExceptionOr<JS::NonnullGCPtr<EventSource>> construct_impl(JS::Realm&, StringView url, EventSourceInit event_source_init_dict = {});
+
+    // https://html.spec.whatwg.org/multipage/server-sent-events.html#dom-eventsource-url
+    String url() const { return MUST(String::from_byte_string(m_url.serialize())); }
+
+    // https://html.spec.whatwg.org/multipage/server-sent-events.html#dom-eventsource-withcredentials
+    bool with_credentials() const { return m_with_credentials; }
+
+    enum class ReadyState : WebIDL::UnsignedShort {
+        Connecting = 0,
+        Open = 1,
+        Closed = 2,
+    };
+
+    // https://html.spec.whatwg.org/multipage/server-sent-events.html#dom-eventsource-readystate
+    ReadyState ready_state() const { return m_ready_state; }
+
+    void set_onopen(WebIDL::CallbackType*);
+    WebIDL::CallbackType* onopen();
+
+    void set_onmessage(WebIDL::CallbackType*);
+    WebIDL::CallbackType* onmessage();
+
+    void set_onerror(WebIDL::CallbackType*);
+    WebIDL::CallbackType* onerror();
+
+    void close();
+    void forcibly_close();
+
+private:
+    explicit EventSource(JS::Realm&);
+
+    virtual void initialize(JS::Realm&) override;
+    virtual void finalize() override;
+    virtual void visit_edges(Cell::Visitor&) override;
+
+    void announce_the_connection();
+    void reestablish_the_connection();
+    void fail_the_connection();
+
+    void interpret_response(StringView);
+    void process_field(StringView field, StringView value);
+    void dispatch_the_event();
+
+    // https://html.spec.whatwg.org/multipage/server-sent-events.html#concept-eventsource-url
+    URL::URL m_url;
+
+    // https://html.spec.whatwg.org/multipage/server-sent-events.html#concept-event-stream-request
+    JS::GCPtr<Fetch::Infrastructure::Request> m_request;
+
+    // https://html.spec.whatwg.org/multipage/server-sent-events.html#concept-event-stream-reconnection-time
+    Duration m_reconnection_time { Duration::from_seconds(3) };
+
+    // https://html.spec.whatwg.org/multipage/server-sent-events.html#concept-event-stream-last-event-id
+    String m_last_event_id;
+
+    String m_event_type;
+    StringBuilder m_data;
+
+    bool m_with_credentials { false };
+
+    ReadyState m_ready_state { ReadyState::Connecting };
+
+    JS::GCPtr<Fetch::Infrastructure::FetchAlgorithms> m_fetch_algorithms;
+    JS::GCPtr<Fetch::Infrastructure::FetchController> m_fetch_controller;
+};
+
+}
diff --git a/Userland/Libraries/LibWeb/HTML/EventSource.idl b/Userland/Libraries/LibWeb/HTML/EventSource.idl
@@ -0,0 +1,27 @@
+#import <DOM/EventHandler.idl>
+#import <DOM/EventTarget.idl>
+
+// https://html.spec.whatwg.org/multipage/server-sent-events.html#eventsource
+[Exposed=(Window,Worker)]
+interface EventSource : EventTarget {
+    constructor(USVString url, optional EventSourceInit eventSourceInitDict = {});
+
+    readonly attribute USVString url;
+    readonly attribute boolean withCredentials;
+
+    // ready state
+    const unsigned short CONNECTING = 0;
+    const unsigned short OPEN = 1;
+    const unsigned short CLOSED = 2;
+    readonly attribute unsigned short readyState;
+
+    // networking
+    attribute EventHandler onopen;
+    attribute EventHandler onmessage;
+    attribute EventHandler onerror;
+    undefined close();
+};
+
+dictionary EventSourceInit {
+    boolean withCredentials = false;
+};
diff --git a/Userland/Libraries/LibWeb/HTML/WindowOrWorkerGlobalScope.cpp b/Userland/Libraries/LibWeb/HTML/WindowOrWorkerGlobalScope.cpp
@@ -18,6 +18,7 @@
 #include <LibWeb/Fetch/FetchMethod.h>
 #include <LibWeb/HTML/CanvasRenderingContext2D.h>
 #include <LibWeb/HTML/EventLoop/EventLoop.h>
+#include <LibWeb/HTML/EventSource.h>
 #include <LibWeb/HTML/ImageBitmap.h>
 #include <LibWeb/HTML/Scripting/ClassicScript.h>
 #include <LibWeb/HTML/Scripting/Environments.h>
@@ -70,6 +71,7 @@ void WindowOrWorkerGlobalScopeMixin::visit_edges(JS::Cell::Visitor& visitor)
     visitor.visit(m_indexed_db);
     for (auto& entry : m_performance_entry_buffer_map)
         entry.value.visit_edges(visitor);
+    visitor.visit(m_registered_event_sources);
 }
 
 void WindowOrWorkerGlobalScopeMixin::finalize()
@@ -649,6 +651,22 @@ void WindowOrWorkerGlobalScopeMixin::queue_the_performance_observer_task()
     }));
 }
 
+void WindowOrWorkerGlobalScopeMixin::register_event_source(Badge<EventSource>, JS::NonnullGCPtr<EventSource> event_source)
+{
+    m_registered_event_sources.set(event_source);
+}
+
+void WindowOrWorkerGlobalScopeMixin::unregister_event_source(Badge<EventSource>, JS::NonnullGCPtr<EventSource> event_source)
+{
+    m_registered_event_sources.remove(event_source);
+}
+
+void WindowOrWorkerGlobalScopeMixin::forcibly_close_all_event_sources()
+{
+    for (auto event_source : m_registered_event_sources)
+        event_source->forcibly_close();
+}
+
 // https://html.spec.whatwg.org/multipage/timers-and-user-prompts.html#run-steps-after-a-timeout
 void WindowOrWorkerGlobalScopeMixin::run_steps_after_a_timeout(i32 timeout, Function<void()> completion_step)
 {

diff --git a/Userland/Libraries/LibWeb/HTML/WindowOrWorkerGlobalScope.h b/Userland/Libraries/LibWeb/HTML/WindowOrWorkerGlobalScope.h
@@ -64,6 +64,10 @@ class WindowOrWorkerGlobalScopeMixin {
 
     void queue_the_performance_observer_task();
 
+    void register_event_source(Badge<EventSource>, JS::NonnullGCPtr<EventSource>);
+    void unregister_event_source(Badge<EventSource>, JS::NonnullGCPtr<EventSource>);
+    void forcibly_close_all_event_sources();
+
     void run_steps_after_a_timeout(i32 timeout, Function<void()> completion_step);
 
     [[nodiscard]] JS::NonnullGCPtr<HighResolutionTime::Performance> performance();
@@ -103,6 +107,8 @@ class WindowOrWorkerGlobalScopeMixin {
     // NOTE: See the PerformanceEntryTuple struct above for the map's value tuple.
     OrderedHashMap<FlyString, PerformanceTimeline::PerformanceEntryTuple> m_performance_entry_buffer_map;
 
+    HashTable<JS::NonnullGCPtr<EventSource>> m_registered_event_sources;
+
     JS::GCPtr<HighResolutionTime::Performance> m_performance;
 
     JS::GCPtr<IndexedDB::IDBFactory> m_indexed_db;

diff --git a/Userland/Libraries/LibWeb/idl_files.cmake b/Userland/Libraries/LibWeb/idl_files.cmake
@@ -103,6 +103,7 @@ libweb_js_bindings(HTML/DOMParser)
 libweb_js_bindings(HTML/DOMStringMap)
 libweb_js_bindings(HTML/DataTransfer)
 libweb_js_bindings(HTML/ErrorEvent)
+libweb_js_bindings(HTML/EventSource)
 libweb_js_bindings(HTML/FormDataEvent)
 libweb_js_bindings(HTML/HashChangeEvent)
 libweb_js_bindings(HTML/History)