modules/websockets/WebSocketDeflateFramer.cpp

/*
 * Copyright (C) 2012 Google Inc.  All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 * in the documentation and/or other materials provided with the
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#include "config.h"

#include "modules/websockets/WebSocketDeflateFramer.h"

#include "wtf/HashMap.h"
#include "wtf/text/StringHash.h"
#include "wtf/text/WTFString.h"

namespace WebCore {

class WebSocketExtensionDeflateFrame : public WebSocketExtensionProcessor {
    WTF_MAKE_FAST_ALLOCATED;
public:
    static PassOwnPtr<WebSocketExtensionDeflateFrame> create(WebSocketDeflateFramer* framer)
    {
        return adoptPtr(new WebSocketExtensionDeflateFrame(framer));
    }
    virtual ~WebSocketExtensionDeflateFrame() { }

    virtual String handshakeString() OVERRIDE;
    virtual bool processResponse(const HashMap<String, String>&) OVERRIDE;
    virtual String failureReason() OVERRIDE { return m_failureReason; }

private:
    WebSocketExtensionDeflateFrame(WebSocketDeflateFramer*);

    WebSocketDeflateFramer* m_framer;
    bool m_responseProcessed;
    String m_failureReason;
};

// FXIME: Remove vendor prefix after the specification matured.
WebSocketExtensionDeflateFrame::WebSocketExtensionDeflateFrame(WebSocketDeflateFramer* framer)
    : WebSocketExtensionProcessor("x-webkit-deflate-frame")
    , m_framer(framer)
    , m_responseProcessed(false)
{
    ASSERT(m_framer);
}

String WebSocketExtensionDeflateFrame::handshakeString()
{
    return extensionToken(); // No parameter
}

bool WebSocketExtensionDeflateFrame::processResponse(const HashMap<String, String>& serverParameters)
{
    if (m_responseProcessed) {
        m_failureReason = "Received duplicate deflate-frame response";
        return false;
    }
    m_responseProcessed = true;

    unsigned expectedNumParameters = 0;
    int windowBits = 15;
    HashMap<String, String>::const_iterator parameter = serverParameters.find("max_window_bits");
    if (parameter != serverParameters.end()) {
        windowBits = parameter->value.toInt();
        if (windowBits < 8 || windowBits > 15) {
            m_failureReason = "Received invalid max_window_bits parameter";
            return false;
        }
        expectedNumParameters++;
    }

    WebSocketDeflater::ContextTakeOverMode mode = WebSocketDeflater::TakeOverContext;
    parameter = serverParameters.find("no_context_takeover");
    if (parameter != serverParameters.end()) {
        if (!parameter->value.isNull()) {
            m_failureReason = "Received invalid no_context_takeover parameter";
            return false;
        }
        mode = WebSocketDeflater::DoNotTakeOverContext;
        expectedNumParameters++;
    }

    if (expectedNumParameters != serverParameters.size()) {
        m_failureReason = "Received unexpected deflate-frame parameter";
        return false;
    }

    m_framer->enableDeflate(windowBits, mode);
    return true;
}

DeflateResultHolder::DeflateResultHolder(WebSocketDeflateFramer* framer)
    : m_framer(framer)
    , m_succeeded(true)
{
    ASSERT(m_framer);
}

DeflateResultHolder::~DeflateResultHolder()
{
    m_framer->resetDeflateContext();
}

void DeflateResultHolder::fail(const String& failureReason)
{
    m_succeeded = false;
    m_failureReason = failureReason;
}

InflateResultHolder::InflateResultHolder(WebSocketDeflateFramer* framer)
    : m_framer(framer)
    , m_succeeded(true)
{
    ASSERT(m_framer);
}

InflateResultHolder::~InflateResultHolder()
{
    m_framer->resetInflateContext();
}

void InflateResultHolder::fail(const String& failureReason)
{
    m_succeeded = false;
    m_failureReason = failureReason;
}

WebSocketDeflateFramer::WebSocketDeflateFramer()
    : m_enabled(false)
{
}

PassOwnPtr<WebSocketExtensionProcessor> WebSocketDeflateFramer::createExtensionProcessor()
{
    return WebSocketExtensionDeflateFrame::create(this);
}

void WebSocketDeflateFramer::enableDeflate(int windowBits, WebSocketDeflater::ContextTakeOverMode mode)
{
    m_deflater = WebSocketDeflater::create(windowBits, mode);
    m_inflater = WebSocketInflater::create();
    if (!m_deflater->initialize() || !m_inflater->initialize()) {
        m_deflater.clear();
        m_inflater.clear();
        return;
    }
    m_enabled = true;
}

PassOwnPtr<DeflateResultHolder> WebSocketDeflateFramer::deflate(WebSocketFrame& frame)
{
    OwnPtr<DeflateResultHolder> result = DeflateResultHolder::create(this);
    if (!enabled() || !WebSocketFrame::isNonControlOpCode(frame.opCode) || !frame.payloadLength)
        return result.release();
    if (!m_deflater->addBytes(frame.payload, frame.payloadLength) || !m_deflater->finish()) {
        result->fail("Failed to compress frame");
        return result.release();
    }
    frame.compress = true;
    frame.payload = m_deflater->data();
    frame.payloadLength = m_deflater->size();
    return result.release();
}

void WebSocketDeflateFramer::resetDeflateContext()
{
    if (m_deflater)
        m_deflater->reset();
}

PassOwnPtr<InflateResultHolder> WebSocketDeflateFramer::inflate(WebSocketFrame& frame)
{
    OwnPtr<InflateResultHolder> result = InflateResultHolder::create(this);
    if (!enabled())
        return result.release();
    if (!frame.compress)
        return result.release();
    if (!WebSocketFrame::isNonControlOpCode(frame.opCode)) {
        result->fail("Received unexpected compressed frame");
        return result.release();
    }
    if (!m_inflater->addBytes(frame.payload, frame.payloadLength) || !m_inflater->finish()) {
        result->fail("Failed to decompress frame");
        return result.release();
    }
    frame.compress = false;
    frame.payload = m_inflater->data();
    frame.payloadLength = m_inflater->size();
    return result.release();
}

void WebSocketDeflateFramer::resetInflateContext()
{
    if (m_inflater)
        m_inflater->reset();
}

void WebSocketDeflateFramer::didFail()
{
    resetDeflateContext();
    resetInflateContext();
}

} // namespace WebCore