Source/WebCore/dom/MessagePort.cpp

/*
 * Copyright (C) 2008 Apple Inc. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE INC. 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 "MessagePort.h"

#include "Document.h"
#include "ExceptionCode.h"
#include "MessageEvent.h"
#include "SecurityOrigin.h"
#include "WorkerGlobalScope.h"

namespace WebCore {

MessagePort::MessagePort(ScriptExecutionContext& scriptExecutionContext)
    : m_started(false)
    , m_closed(false)
    , m_scriptExecutionContext(&scriptExecutionContext)
{
    m_scriptExecutionContext->createdMessagePort(*this);

    // Don't need to call processMessagePortMessagesSoon() here, because the port will not be opened until start() is invoked.
}

MessagePort::~MessagePort()
{
    close();
    if (m_scriptExecutionContext)
        m_scriptExecutionContext->destroyedMessagePort(*this);
}

void MessagePort::postMessage(PassRefPtr<SerializedScriptValue> message, MessagePort* port, ExceptionCode& ec)
{
    MessagePortArray ports;
    if (port)
        ports.append(port);
    postMessage(message, &ports, ec);
}

void MessagePort::postMessage(PassRefPtr<SerializedScriptValue> message, const MessagePortArray* ports, ExceptionCode& ec)
{
    if (!isEntangled())
        return;
    ASSERT(m_scriptExecutionContext);

    std::unique_ptr<MessagePortChannelArray> channels;
    // Make sure we aren't connected to any of the passed-in ports.
    if (ports) {
        for (auto& dataPort : *ports) {
            if (dataPort == this || m_entangledChannel->isConnectedTo(dataPort.get())) {
                ec = DATA_CLONE_ERR;
                return;
            }
        }
        channels = MessagePort::disentanglePorts(ports, ec);
        if (ec)
            return;
    }
    m_entangledChannel->postMessageToRemote(message, WTFMove(channels));
}

std::unique_ptr<MessagePortChannel> MessagePort::disentangle()
{
    ASSERT(m_entangledChannel);

    m_entangledChannel->disentangle();

    // We can't receive any messages or generate any events after this, so remove ourselves from the list of active ports.
    ASSERT(m_scriptExecutionContext);
    m_scriptExecutionContext->destroyedMessagePort(*this);
    m_scriptExecutionContext = nullptr;

    return WTFMove(m_entangledChannel);
}

// Invoked to notify us that there are messages available for this port.
// This code may be called from another thread, and so should not call any non-threadsafe APIs (i.e. should not call into the entangled channel or access mutable variables).
void MessagePort::messageAvailable()
{
    ASSERT(m_scriptExecutionContext);
    m_scriptExecutionContext->processMessagePortMessagesSoon();
}

void MessagePort::start()
{
    // Do nothing if we've been cloned or closed.
    if (!isEntangled())
        return;

    ASSERT(m_scriptExecutionContext);
    if (m_started)
        return;

    m_started = true;
    m_scriptExecutionContext->processMessagePortMessagesSoon();
}

void MessagePort::close()
{
    if (isEntangled())
        m_entangledChannel->close();
    m_closed = true;
}

void MessagePort::entangle(std::unique_ptr<MessagePortChannel> remote)
{
    // Only invoked to set our initial entanglement.
    ASSERT(!m_entangledChannel);
    ASSERT(m_scriptExecutionContext);

    // Don't entangle the ports if the channel is closed.
    if (remote->entangleIfOpen(this))
        m_entangledChannel = WTFMove(remote);
}

void MessagePort::contextDestroyed()
{
    ASSERT(m_scriptExecutionContext);
    // Must be closed before blowing away the cached context, to ensure that we get no more calls to messageAvailable().
    // ScriptExecutionContext::closeMessagePorts() takes care of that.
    ASSERT(m_closed);
    m_scriptExecutionContext = nullptr;
}

void MessagePort::dispatchMessages()
{
    // Messages for contexts that are not fully active get dispatched too, but JSAbstractEventListener::handleEvent() doesn't call handlers for these.
    // The HTML5 spec specifies that any messages sent to a document that is not fully active should be dropped, so this behavior is OK.
    ASSERT(started());

    RefPtr<SerializedScriptValue> message;
    std::unique_ptr<MessagePortChannelArray> channels;
    while (m_entangledChannel && m_entangledChannel->tryGetMessageFromRemote(message, channels)) {

        // close() in Worker onmessage handler should prevent next message from dispatching.
        if (is<WorkerGlobalScope>(*m_scriptExecutionContext) && downcast<WorkerGlobalScope>(*m_scriptExecutionContext).isClosing())
            return;

        std::unique_ptr<MessagePortArray> ports = MessagePort::entanglePorts(*m_scriptExecutionContext, WTFMove(channels));
        Ref<Event> event = MessageEvent::create(WTFMove(ports), message.release());
        dispatchEvent(event);
    }
}

bool MessagePort::hasPendingActivity()
{
    // The spec says that entangled message ports should always be treated as if they have a strong reference.
    // We'll also stipulate that the queue needs to be open (if the app drops its reference to the port before start()-ing it, then it's not really entangled as it's unreachable).
    if (m_started && m_entangledChannel && m_entangledChannel->hasPendingActivity())
        return true;
    if (isEntangled() && !locallyEntangledPort())
        return true;
    return false;
}

MessagePort* MessagePort::locallyEntangledPort()
{
    return m_entangledChannel ? m_entangledChannel->locallyEntangledPort(m_scriptExecutionContext) : nullptr;
}

std::unique_ptr<MessagePortChannelArray> MessagePort::disentanglePorts(const MessagePortArray* ports, ExceptionCode& ec)
{
    if (!ports || !ports->size())
        return nullptr;

    // HashSet used to efficiently check for duplicates in the passed-in array.
    HashSet<MessagePort*> portSet;

    // Walk the incoming array - if there are any duplicate ports, or null ports or cloned ports, throw an error (per section 8.3.3 of the HTML5 spec).
    for (auto& port : *ports) {
        if (!port || port->isNeutered() || portSet.contains(port.get())) {
            ec = DATA_CLONE_ERR;
            return nullptr;
        }
        portSet.add(port.get());
    }

    // Passed-in ports passed validity checks, so we can disentangle them.
    auto portArray = std::make_unique<MessagePortChannelArray>(ports->size());
    for (unsigned int i = 0 ; i < ports->size() ; ++i) {
        std::unique_ptr<MessagePortChannel> channel = (*ports)[i]->disentangle();
        (*portArray)[i] = WTFMove(channel);
    }
    return portArray;
}

std::unique_ptr<MessagePortArray> MessagePort::entanglePorts(ScriptExecutionContext& context, std::unique_ptr<MessagePortChannelArray> channels)
{
    if (!channels || !channels->size())
        return nullptr;

    auto portArray = std::make_unique<MessagePortArray>(channels->size());
    for (unsigned int i = 0; i < channels->size(); ++i) {
        RefPtr<MessagePort> port = MessagePort::create(context);
        port->entangle(WTFMove((*channels)[i]));
        (*portArray)[i] = port.release();
    }
    return portArray;
}

bool MessagePort::addEventListener(const AtomicString& eventType, RefPtr<EventListener>&& listener, bool useCapture)
{
    if (listener && listener->isAttribute() && eventType == eventNames().messageEvent)
        start();
    return EventTargetWithInlineData::addEventListener(eventType, WTFMove(listener), useCapture);
}

} // namespace WebCore