Source/WebCore/page/EventSource.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 2009, 2012 Ericsson AB. All rights reserved.
  * Copyright (C) 2010, 2016 Apple Inc. All rights reserved.
  * Copyright (C) 2011, Code Aurora Forum. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer
  *    in the documentation and/or other materials provided with the
  *    distribution.
  * 3. Neither the name of Ericsson nor the names of its contributors
  *    may be used to endorse or promote products derived from this
  *    software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "config.h"
 #include "EventSource.h"

 #include "CachedResourceRequestInitiators.h"
 #include "ContentSecurityPolicy.h"
 #include "EventNames.h"
 #include "MessageEvent.h"
 #include "ResourceError.h"
 #include "ResourceRequest.h"
 #include "ResourceResponse.h"
 #include "ScriptExecutionContext.h"
 #include "SecurityOrigin.h"
 #include "TextResourceDecoder.h"
 #include "ThreadableLoader.h"
 #include <wtf/IsoMallocInlines.h>
 #include <wtf/SetForScope.h>

 namespace WebCore {

 WTF_MAKE_ISO_ALLOCATED_IMPL(EventSource);

 const uint64_t EventSource::defaultReconnectDelay = 3000;

 inline EventSource::EventSource(ScriptExecutionContext& context, const URL& url, const Init& eventSourceInit)
     : ActiveDOMObject(&context)
     , m_url(url)
     , m_withCredentials(eventSourceInit.withCredentials)
     , m_decoder(TextResourceDecoder::create("text/plain"_s, "UTF-8"))
     , m_connectTimer(&context, *this, &EventSource::connect)
 {
     m_connectTimer.suspendIfNeeded();
 }

 ExceptionOr<Ref<EventSource>> EventSource::create(ScriptExecutionContext& context, const String& url, const Init& eventSourceInit)
 {
     if (url.isEmpty())
         return Exception { SyntaxError };

     URL fullURL = context.completeURL(url);
     if (!fullURL.isValid())
         return Exception { SyntaxError };

     // FIXME: Convert this to check the isolated world's Content Security Policy once webkit.org/b/104520 is resolved.
     if (!context.shouldBypassMainWorldContentSecurityPolicy() && !context.contentSecurityPolicy()->allowConnectToSource(fullURL)) {
         // FIXME: Should this be throwing an exception?
         return Exception { SecurityError };
     }

     auto source = adoptRef(*new EventSource(context, fullURL, eventSourceInit));
     source->setPendingActivity(source.get());
     source->scheduleInitialConnect();
     source->suspendIfNeeded();
     return source;
 }

 EventSource::~EventSource()
 {
     ASSERT(m_state == CLOSED);
     ASSERT(!m_requestInFlight);
 }

 void EventSource::connect()
 {
     ASSERT(m_state == CONNECTING);
     ASSERT(!m_requestInFlight);

     ResourceRequest request { m_url };
     request.setHTTPMethod("GET");
     request.setHTTPHeaderField(HTTPHeaderName::Accept, "text/event-stream");
     request.setHTTPHeaderField(HTTPHeaderName::CacheControl, "no-cache");
     if (!m_lastEventId.isEmpty())
         request.setHTTPHeaderField(HTTPHeaderName::LastEventID, m_lastEventId);

     ThreadableLoaderOptions options;
     options.sendLoadCallbacks = SendCallbackPolicy::SendCallbacks;
     options.credentials = m_withCredentials ? FetchOptions::Credentials::Include : FetchOptions::Credentials::SameOrigin;
     options.preflightPolicy = PreflightPolicy::Prevent;
     options.mode = FetchOptions::Mode::Cors;
     options.cache = FetchOptions::Cache::NoStore;
     options.dataBufferingPolicy = DataBufferingPolicy::DoNotBufferData;
     options.contentSecurityPolicyEnforcement = scriptExecutionContext()->shouldBypassMainWorldContentSecurityPolicy() ? ContentSecurityPolicyEnforcement::DoNotEnforce : ContentSecurityPolicyEnforcement::EnforceConnectSrcDirective;
     options.initiator = cachedResourceRequestInitiators().eventsource;

     ASSERT(scriptExecutionContext());
     m_loader = ThreadableLoader::create(*scriptExecutionContext(), *this, WTFMove(request), options);

     // FIXME: Can we just use m_loader for this, null it out when it's no longer in flight, and eliminate the m_requestInFlight member?
     if (m_loader)
         m_requestInFlight = true;
 }

 void EventSource::networkRequestEnded()
 {
     ASSERT(m_requestInFlight);

     m_requestInFlight = false;

     if (m_state != CLOSED)
         scheduleReconnect();
     else
         unsetPendingActivity(*this);
 }

 void EventSource::scheduleInitialConnect()
 {
     ASSERT(m_state == CONNECTING);
     ASSERT(!m_requestInFlight);

     m_connectTimer.startOneShot(0_s);
 }

 void EventSource::scheduleReconnect()
 {
     RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_isSuspendedForPageCache);
     m_state = CONNECTING;
     m_connectTimer.startOneShot(1_ms * m_reconnectDelay);
     dispatchErrorEvent();
 }

 void EventSource::close()
 {
     if (m_state == CLOSED) {
         ASSERT(!m_requestInFlight);
         return;
     }

     // Stop trying to connect/reconnect if EventSource was explicitly closed or if ActiveDOMObject::stop() was called.
     if (m_connectTimer.isActive())
         m_connectTimer.cancel();

     if (m_requestInFlight)
         doExplicitLoadCancellation();
     else {
         m_state = CLOSED;
         unsetPendingActivity(*this);
     }
 }

 bool EventSource::responseIsValid(const ResourceResponse& response) const
 {
     // Logs to the console as a side effect.

     // To keep the signal-to-noise ratio low, we don't log anything if the status code is not 200.
     if (response.httpStatusCode() != 200)
         return false;

     if (!equalLettersIgnoringASCIICase(response.mimeType(), "text/event-stream")) {
         auto message = makeString("EventSource's response has a MIME type (\"", response.mimeType(), "\") that is not \"text/event-stream\". Aborting the connection.");
         // FIXME: Console message would be better with a source code location; where would we get that?
         scriptExecutionContext()->addConsoleMessage(MessageSource::JS, MessageLevel::Error, WTFMove(message));
         return false;
     }

     // If we have a charset, the only allowed value is UTF-8 (case-insensitive).
     auto& charset = response.textEncodingName();
     if (!charset.isEmpty() && !equalLettersIgnoringASCIICase(charset, "utf-8")) {
         auto message = makeString("EventSource's response has a charset (\"", charset, "\") that is not UTF-8. Aborting the connection.");
         // FIXME: Console message would be better with a source code location; where would we get that?
         scriptExecutionContext()->addConsoleMessage(MessageSource::JS, MessageLevel::Error, WTFMove(message));
         return false;
     }

     return true;
 }

 void EventSource::didReceiveResponse(unsigned long, const ResourceResponse& response)
 {
     ASSERT(m_state == CONNECTING);
     ASSERT(m_requestInFlight);
     RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_isSuspendedForPageCache);

     if (!responseIsValid(response)) {
         doExplicitLoadCancellation();
         dispatchErrorEvent();
         return;
     }

     m_eventStreamOrigin = SecurityOriginData::fromURL(response.url()).toString();
     m_state = OPEN;
     dispatchEvent(Event::create(eventNames().openEvent, Event::CanBubble::No, Event::IsCancelable::No));
 }

 void EventSource::dispatchErrorEvent()
 {
     dispatchEvent(Event::create(eventNames().errorEvent, Event::CanBubble::No, Event::IsCancelable::No));
 }

 void EventSource::didReceiveData(const char* data, int length)
 {
     ASSERT(m_state == OPEN);
     ASSERT(m_requestInFlight);
     RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_isSuspendedForPageCache);

     append(m_receiveBuffer, m_decoder->decode(data, length));
     parseEventStream();
 }

 void EventSource::didFinishLoading(unsigned long)
 {
     ASSERT(m_state == OPEN);
     ASSERT(m_requestInFlight);
     RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_isSuspendedForPageCache);

     append(m_receiveBuffer, m_decoder->flush());
     parseEventStream();

     // Discard everything that has not been dispatched by now.
     // FIXME: Why does this need to be done?
     // If this is important, why isn't it important to clear other data members: m_decoder, m_lastEventId, m_loader?
     m_receiveBuffer.clear();
     m_data.clear();
     m_eventName = { };
     m_currentlyParsedEventId = { };

     networkRequestEnded();
 }

 void EventSource::didFail(const ResourceError& error)
 {
     ASSERT(m_state != CLOSED);

     if (error.isAccessControl()) {
         abortConnectionAttempt();
         return;
     }

     ASSERT(m_requestInFlight);

     // This is the case where the load gets cancelled on navigating away. We only fire an error event and attempt to reconnect
     // if we end up getting resumed from page cache.
     if (error.isCancellation() && !m_isDoingExplicitCancellation) {
         m_shouldReconnectOnResume = true;
         m_requestInFlight = false;
         return;
     }

     if (error.isCancellation())
         m_state = CLOSED;

     // FIXME: Why don't we need to clear data members here as in didFinishLoading?

     networkRequestEnded();
 }

 void EventSource::abortConnectionAttempt()
 {
     ASSERT(m_state == CONNECTING);
     RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_isSuspendedForPageCache);

     if (m_requestInFlight)
         doExplicitLoadCancellation();
     else {
         m_state = CLOSED;
         unsetPendingActivity(*this);
     }

     ASSERT(m_state == CLOSED);
     dispatchEvent(Event::create(eventNames().errorEvent, Event::CanBubble::No, Event::IsCancelable::No));
 }

 void EventSource::doExplicitLoadCancellation()
 {
     ASSERT(m_requestInFlight);
     SetForScope<bool> explicitLoadCancellation(m_isDoingExplicitCancellation, true);
     m_loader->cancel();
 }

 void EventSource::parseEventStream()
 {
     unsigned position = 0;
     unsigned size = m_receiveBuffer.size();
     while (position < size) {
         if (m_discardTrailingNewline) {
             if (m_receiveBuffer[position] == '\n')
                 ++position;
             m_discardTrailingNewline = false;
         }

         Optional<unsigned> lineLength;
         Optional<unsigned> fieldLength;
         for (unsigned i = position; !lineLength && i < size; ++i) {
             switch (m_receiveBuffer[i]) {
             case ':':
                 if (!fieldLength)
                     fieldLength = i - position;
                 break;
             case '\r':
                 m_discardTrailingNewline = true;
                 FALLTHROUGH;
             case '\n':
                 lineLength = i - position;
                 break;
             }
         }

         if (!lineLength)
             break;

         parseEventStreamLine(position, fieldLength, lineLength.value());
         position += lineLength.value() + 1;

         // EventSource.close() might've been called by one of the message event handlers.
         // Per spec, no further messages should be fired after that.
         if (m_state == CLOSED)
             break;
     }

     // FIXME: The following operation makes it clear that m_receiveBuffer should be some other type,
     // perhaps a Deque or a circular buffer of some sort.
     if (position == size)
         m_receiveBuffer.clear();
     else if (position)
         m_receiveBuffer.remove(0, position);
 }

 void EventSource::parseEventStreamLine(unsigned position, Optional<unsigned> fieldLength, unsigned lineLength)
 {
     if (!lineLength) {
         if (!m_data.isEmpty())
             dispatchMessageEvent();
         m_eventName = { };
         return;
     }

     if (fieldLength && !fieldLength.value())
         return;

     StringView field { &m_receiveBuffer[position], fieldLength ? fieldLength.value() : lineLength };

     unsigned step;
     if (!fieldLength)
         step = lineLength;
     else if (m_receiveBuffer[position + fieldLength.value() + 1] != ' ')
         step = fieldLength.value() + 1;
     else
         step = fieldLength.value() + 2;
     position += step;
     unsigned valueLength = lineLength - step;

     if (field == "data") {
         m_data.append(&m_receiveBuffer[position], valueLength);
         m_data.append('\n');
     } else if (field == "event")
         m_eventName = { &m_receiveBuffer[position], valueLength };
     else if (field == "id") {
         StringView parsedEventId = { &m_receiveBuffer[position], valueLength };
         constexpr UChar nullCharacter = '\0';
         if (!parsedEventId.contains(nullCharacter))
             m_currentlyParsedEventId = parsedEventId.toString();
     } else if (field == "retry") {
         if (!valueLength)
             m_reconnectDelay = defaultReconnectDelay;
         else {
             // FIXME: Do we really want to ignore trailing garbage here? Should we be using the strict version instead?
             // FIXME: If we can't parse the value, should we leave m_reconnectDelay alone or set it to defaultReconnectDelay?
             bool ok;
             auto reconnectDelay = charactersToUInt64(&m_receiveBuffer[position], valueLength, &ok);
             if (ok)
                 m_reconnectDelay = reconnectDelay;
         }
     }
 }

 void EventSource::stop()
 {
     close();
 }

 const char* EventSource::activeDOMObjectName() const
 {
     return "EventSource";
 }

 bool EventSource::canSuspendForDocumentSuspension() const
 {
     return true;
 }

 void EventSource::suspend(ReasonForSuspension reason)
 {
     if (reason != ReasonForSuspension::PageCache)
         return;

     m_isSuspendedForPageCache = true;
     RELEASE_ASSERT_WITH_MESSAGE(!m_requestInFlight, "Loads get cancelled before entering PageCache.");
 }

 void EventSource::resume()
 {
     if (!m_isSuspendedForPageCache)
         return;

     m_isSuspendedForPageCache = false;
     if (std::exchange(m_shouldReconnectOnResume, false)) {
         scriptExecutionContext()->postTask([this, pendingActivity = makePendingActivity(*this)](ScriptExecutionContext&) {
             if (!isContextStopped())
                 scheduleReconnect();
         });
     }
 }

 void EventSource::dispatchMessageEvent()
 {
     RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_isSuspendedForPageCache);

     if (!m_currentlyParsedEventId.isNull())
         m_lastEventId = WTFMove(m_currentlyParsedEventId);

     auto& name = m_eventName.isEmpty() ? eventNames().messageEvent : m_eventName;

     // Omit the trailing "\n" character.
     ASSERT(!m_data.isEmpty());
     unsigned size = m_data.size() - 1;
     auto data = SerializedScriptValue::create({ m_data.data(), size });
     RELEASE_ASSERT(data);
     m_data = { };

     dispatchEvent(MessageEvent::create(name, data.releaseNonNull(), m_eventStreamOrigin, m_lastEventId));
 }

 } // namespace WebCore
	/*
	* Copyright (C) 2009, 2012 Ericsson AB. All rights reserved.
	* Copyright (C) 2010, 2016 Apple Inc. All rights reserved.
	* Copyright (C) 2011, Code Aurora Forum. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer
	* in the documentation and/or other materials provided with the
	* distribution.
	* 3. Neither the name of Ericsson nor the names of its contributors
	* may be used to endorse or promote products derived from this
	* software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "config.h"
	#include "EventSource.h"

	#include "CachedResourceRequestInitiators.h"
	#include "ContentSecurityPolicy.h"
	#include "EventNames.h"
	#include "MessageEvent.h"
	#include "ResourceError.h"
	#include "ResourceRequest.h"
	#include "ResourceResponse.h"
	#include "ScriptExecutionContext.h"
	#include "SecurityOrigin.h"
	#include "TextResourceDecoder.h"
	#include "ThreadableLoader.h"
	#include <wtf/IsoMallocInlines.h>
	#include <wtf/SetForScope.h>

	namespace WebCore {

	WTF_MAKE_ISO_ALLOCATED_IMPL(EventSource);

	const uint64_t EventSource::defaultReconnectDelay = 3000;

	inline EventSource::EventSource(ScriptExecutionContext& context, const URL& url, const Init& eventSourceInit)
	: ActiveDOMObject(&context)
	, m_url(url)
	, m_withCredentials(eventSourceInit.withCredentials)
	, m_decoder(TextResourceDecoder::create("text/plain"_s, "UTF-8"))
	, m_connectTimer(&context, *this, &EventSource::connect)
	{
	m_connectTimer.suspendIfNeeded();
	}

	ExceptionOr<Ref<EventSource>> EventSource::create(ScriptExecutionContext& context, const String& url, const Init& eventSourceInit)
	{
	if (url.isEmpty())
	return Exception { SyntaxError };

	URL fullURL = context.completeURL(url);
	if (!fullURL.isValid())
	return Exception { SyntaxError };

	// FIXME: Convert this to check the isolated world's Content Security Policy once webkit.org/b/104520 is resolved.
	if (!context.shouldBypassMainWorldContentSecurityPolicy() && !context.contentSecurityPolicy()->allowConnectToSource(fullURL)) {
	// FIXME: Should this be throwing an exception?
	return Exception { SecurityError };
	}

	auto source = adoptRef(*new EventSource(context, fullURL, eventSourceInit));
	source->setPendingActivity(source.get());
	source->scheduleInitialConnect();
	source->suspendIfNeeded();
	return source;
	}

	EventSource::~EventSource()
	{
	ASSERT(m_state == CLOSED);
	ASSERT(!m_requestInFlight);
	}

	void EventSource::connect()
	{
	ASSERT(m_state == CONNECTING);
	ASSERT(!m_requestInFlight);

	ResourceRequest request { m_url };
	request.setHTTPMethod("GET");
	request.setHTTPHeaderField(HTTPHeaderName::Accept, "text/event-stream");
	request.setHTTPHeaderField(HTTPHeaderName::CacheControl, "no-cache");
	if (!m_lastEventId.isEmpty())
	request.setHTTPHeaderField(HTTPHeaderName::LastEventID, m_lastEventId);

	ThreadableLoaderOptions options;
	options.sendLoadCallbacks = SendCallbackPolicy::SendCallbacks;
	options.credentials = m_withCredentials ? FetchOptions::Credentials::Include : FetchOptions::Credentials::SameOrigin;
	options.preflightPolicy = PreflightPolicy::Prevent;
	options.mode = FetchOptions::Mode::Cors;
	options.cache = FetchOptions::Cache::NoStore;
	options.dataBufferingPolicy = DataBufferingPolicy::DoNotBufferData;
	options.contentSecurityPolicyEnforcement = scriptExecutionContext()->shouldBypassMainWorldContentSecurityPolicy() ? ContentSecurityPolicyEnforcement::DoNotEnforce : ContentSecurityPolicyEnforcement::EnforceConnectSrcDirective;
	options.initiator = cachedResourceRequestInitiators().eventsource;

	ASSERT(scriptExecutionContext());
	m_loader = ThreadableLoader::create(scriptExecutionContext(), this, WTFMove(request), options);

	// FIXME: Can we just use m_loader for this, null it out when it's no longer in flight, and eliminate the m_requestInFlight member?
	if (m_loader)
	m_requestInFlight = true;
	}

	void EventSource::networkRequestEnded()
	{
	ASSERT(m_requestInFlight);

	m_requestInFlight = false;

	if (m_state != CLOSED)
	scheduleReconnect();
	else
	unsetPendingActivity(*this);
	}

	void EventSource::scheduleInitialConnect()
	{
	ASSERT(m_state == CONNECTING);
	ASSERT(!m_requestInFlight);

	m_connectTimer.startOneShot(0_s);
	}

	void EventSource::scheduleReconnect()
	{
	RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_isSuspendedForPageCache);
	m_state = CONNECTING;
	m_connectTimer.startOneShot(1_ms * m_reconnectDelay);
	dispatchErrorEvent();
	}

	void EventSource::close()
	{
	if (m_state == CLOSED) {
	ASSERT(!m_requestInFlight);
	return;
	}

	// Stop trying to connect/reconnect if EventSource was explicitly closed or if ActiveDOMObject::stop() was called.
	if (m_connectTimer.isActive())
	m_connectTimer.cancel();

	if (m_requestInFlight)
	doExplicitLoadCancellation();
	else {
	m_state = CLOSED;
	unsetPendingActivity(*this);
	}
	}

	bool EventSource::responseIsValid(const ResourceResponse& response) const
	{
	// Logs to the console as a side effect.

	// To keep the signal-to-noise ratio low, we don't log anything if the status code is not 200.
	if (response.httpStatusCode() != 200)
	return false;

	if (!equalLettersIgnoringASCIICase(response.mimeType(), "text/event-stream")) {
	auto message = makeString("EventSource's response has a MIME type (\"", response.mimeType(), "\") that is not \"text/event-stream\". Aborting the connection.");
	// FIXME: Console message would be better with a source code location; where would we get that?
	scriptExecutionContext()->addConsoleMessage(MessageSource::JS, MessageLevel::Error, WTFMove(message));
	return false;
	}

	// If we have a charset, the only allowed value is UTF-8 (case-insensitive).
	auto& charset = response.textEncodingName();
	if (!charset.isEmpty() && !equalLettersIgnoringASCIICase(charset, "utf-8")) {
	auto message = makeString("EventSource's response has a charset (\"", charset, "\") that is not UTF-8. Aborting the connection.");
	// FIXME: Console message would be better with a source code location; where would we get that?
	scriptExecutionContext()->addConsoleMessage(MessageSource::JS, MessageLevel::Error, WTFMove(message));
	return false;
	}

	return true;
	}

	void EventSource::didReceiveResponse(unsigned long, const ResourceResponse& response)
	{
	ASSERT(m_state == CONNECTING);
	ASSERT(m_requestInFlight);
	RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_isSuspendedForPageCache);

	if (!responseIsValid(response)) {
	doExplicitLoadCancellation();
	dispatchErrorEvent();
	return;
	}

	m_eventStreamOrigin = SecurityOriginData::fromURL(response.url()).toString();
	m_state = OPEN;
	dispatchEvent(Event::create(eventNames().openEvent, Event::CanBubble::No, Event::IsCancelable::No));
	}

	void EventSource::dispatchErrorEvent()
	{
	dispatchEvent(Event::create(eventNames().errorEvent, Event::CanBubble::No, Event::IsCancelable::No));
	}

	void EventSource::didReceiveData(const char* data, int length)
	{
	ASSERT(m_state == OPEN);
	ASSERT(m_requestInFlight);
	RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_isSuspendedForPageCache);

	append(m_receiveBuffer, m_decoder->decode(data, length));
	parseEventStream();
	}

	void EventSource::didFinishLoading(unsigned long)
	{
	ASSERT(m_state == OPEN);
	ASSERT(m_requestInFlight);
	RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_isSuspendedForPageCache);

	append(m_receiveBuffer, m_decoder->flush());
	parseEventStream();

	// Discard everything that has not been dispatched by now.
	// FIXME: Why does this need to be done?
	// If this is important, why isn't it important to clear other data members: m_decoder, m_lastEventId, m_loader?
	m_receiveBuffer.clear();
	m_data.clear();
	m_eventName = { };
	m_currentlyParsedEventId = { };

	networkRequestEnded();
	}

	void EventSource::didFail(const ResourceError& error)
	{
	ASSERT(m_state != CLOSED);

	if (error.isAccessControl()) {
	abortConnectionAttempt();
	return;
	}

	ASSERT(m_requestInFlight);

	// This is the case where the load gets cancelled on navigating away. We only fire an error event and attempt to reconnect
	// if we end up getting resumed from page cache.
	if (error.isCancellation() && !m_isDoingExplicitCancellation) {
	m_shouldReconnectOnResume = true;
	m_requestInFlight = false;
	return;
	}

	if (error.isCancellation())
	m_state = CLOSED;

	// FIXME: Why don't we need to clear data members here as in didFinishLoading?

	networkRequestEnded();
	}

	void EventSource::abortConnectionAttempt()
	{
	ASSERT(m_state == CONNECTING);
	RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_isSuspendedForPageCache);

	if (m_requestInFlight)
	doExplicitLoadCancellation();
	else {
	m_state = CLOSED;
	unsetPendingActivity(*this);
	}

	ASSERT(m_state == CLOSED);
	dispatchEvent(Event::create(eventNames().errorEvent, Event::CanBubble::No, Event::IsCancelable::No));
	}

	void EventSource::doExplicitLoadCancellation()
	{
	ASSERT(m_requestInFlight);
	SetForScope<bool> explicitLoadCancellation(m_isDoingExplicitCancellation, true);
	m_loader->cancel();
	}

	void EventSource::parseEventStream()
	{
	unsigned position = 0;
	unsigned size = m_receiveBuffer.size();
	while (position < size) {
	if (m_discardTrailingNewline) {
	if (m_receiveBuffer[position] == '\n')
	++position;
	m_discardTrailingNewline = false;
	}

	Optional<unsigned> lineLength;
	Optional<unsigned> fieldLength;
	for (unsigned i = position; !lineLength && i < size; ++i) {
	switch (m_receiveBuffer[i]) {
	case ':':
	if (!fieldLength)
	fieldLength = i - position;
	break;
	case '\r':
	m_discardTrailingNewline = true;
	FALLTHROUGH;
	case '\n':
	lineLength = i - position;
	break;
	}
	}

	if (!lineLength)
	break;

	parseEventStreamLine(position, fieldLength, lineLength.value());
	position += lineLength.value() + 1;

	// EventSource.close() might've been called by one of the message event handlers.
	// Per spec, no further messages should be fired after that.
	if (m_state == CLOSED)
	break;
	}

	// FIXME: The following operation makes it clear that m_receiveBuffer should be some other type,
	// perhaps a Deque or a circular buffer of some sort.
	if (position == size)
	m_receiveBuffer.clear();
	else if (position)
	m_receiveBuffer.remove(0, position);
	}

	void EventSource::parseEventStreamLine(unsigned position, Optional<unsigned> fieldLength, unsigned lineLength)
	{
	if (!lineLength) {
	if (!m_data.isEmpty())
	dispatchMessageEvent();
	m_eventName = { };
	return;
	}

	if (fieldLength && !fieldLength.value())
	return;

	StringView field { &m_receiveBuffer[position], fieldLength ? fieldLength.value() : lineLength };

	unsigned step;
	if (!fieldLength)
	step = lineLength;
	else if (m_receiveBuffer[position + fieldLength.value() + 1] != ' ')
	step = fieldLength.value() + 1;
	else
	step = fieldLength.value() + 2;
	position += step;
	unsigned valueLength = lineLength - step;

	if (field == "data") {
	m_data.append(&m_receiveBuffer[position], valueLength);
	m_data.append('\n');
	} else if (field == "event")
	m_eventName = { &m_receiveBuffer[position], valueLength };
	else if (field == "id") {
	StringView parsedEventId = { &m_receiveBuffer[position], valueLength };
	constexpr UChar nullCharacter = '\0';
	if (!parsedEventId.contains(nullCharacter))
	m_currentlyParsedEventId = parsedEventId.toString();
	} else if (field == "retry") {
	if (!valueLength)
	m_reconnectDelay = defaultReconnectDelay;
	else {
	// FIXME: Do we really want to ignore trailing garbage here? Should we be using the strict version instead?
	// FIXME: If we can't parse the value, should we leave m_reconnectDelay alone or set it to defaultReconnectDelay?
	bool ok;
	auto reconnectDelay = charactersToUInt64(&m_receiveBuffer[position], valueLength, &ok);
	if (ok)
	m_reconnectDelay = reconnectDelay;
	}
	}
	}

	void EventSource::stop()
	{
	close();
	}

	const char* EventSource::activeDOMObjectName() const
	{
	return "EventSource";
	}

	bool EventSource::canSuspendForDocumentSuspension() const
	{
	return true;
	}

	void EventSource::suspend(ReasonForSuspension reason)
	{
	if (reason != ReasonForSuspension::PageCache)
	return;

	m_isSuspendedForPageCache = true;
	RELEASE_ASSERT_WITH_MESSAGE(!m_requestInFlight, "Loads get cancelled before entering PageCache.");
	}

	void EventSource::resume()
	{
	if (!m_isSuspendedForPageCache)
	return;

	m_isSuspendedForPageCache = false;
	if (std::exchange(m_shouldReconnectOnResume, false)) {
	scriptExecutionContext()->postTask([this, pendingActivity = makePendingActivity(*this)](ScriptExecutionContext&) {
	if (!isContextStopped())
	scheduleReconnect();
	});
	}
	}

	void EventSource::dispatchMessageEvent()
	{
	RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_isSuspendedForPageCache);

	if (!m_currentlyParsedEventId.isNull())
	m_lastEventId = WTFMove(m_currentlyParsedEventId);

	auto& name = m_eventName.isEmpty() ? eventNames().messageEvent : m_eventName;

	// Omit the trailing "\n" character.
	ASSERT(!m_data.isEmpty());
	unsigned size = m_data.size() - 1;
	auto data = SerializedScriptValue::create({ m_data.data(), size });
	RELEASE_ASSERT(data);
	m_data = { };

	dispatchEvent(MessageEvent::create(name, data.releaseNonNull(), m_eventStreamOrigin, m_lastEventId));
	}

	} // namespace WebCore