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// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/websockets/websocket_deflater.h"
#include <string.h>
#include <algorithm>
#include <deque>
#include <vector>
#include "base/logging.h"
#include "net/base/io_buffer.h"
#include "third_party/zlib/zlib.h"
namespace net {
WebSocketDeflater::WebSocketDeflater(ContextTakeOverMode mode)
: mode_(mode), are_bytes_added_(false) {}
WebSocketDeflater::~WebSocketDeflater() {
if (stream_) {
deflateEnd(stream_.get());
stream_.reset(NULL);
}
}
bool WebSocketDeflater::Initialize(int window_bits) {
DCHECK(!stream_);
stream_.reset(new z_stream);
DCHECK_LE(8, window_bits);
DCHECK_GE(15, window_bits);
memset(stream_.get(), 0, sizeof(*stream_));
int result = deflateInit2(stream_.get(),
Z_DEFAULT_COMPRESSION,
Z_DEFLATED,
-window_bits, // Negative value for raw deflate
8, // default mem level
Z_DEFAULT_STRATEGY);
if (result != Z_OK) {
deflateEnd(stream_.get());
stream_.reset();
return false;
}
const size_t kFixedBufferSize = 4096;
fixed_buffer_.resize(kFixedBufferSize);
return true;
}
bool WebSocketDeflater::AddBytes(const char* data, size_t size) {
if (!size)
return true;
are_bytes_added_ = true;
stream_->next_in = reinterpret_cast<Bytef*>(const_cast<char*>(data));
stream_->avail_in = size;
int result = Deflate(Z_NO_FLUSH);
DCHECK(result != Z_BUF_ERROR || !stream_->avail_in);
return result == Z_BUF_ERROR;
}
bool WebSocketDeflater::Finish() {
if (!are_bytes_added_) {
// Since consecutive calls of deflate with Z_SYNC_FLUSH and no input
// lead to an error, we create and return the output for the empty input
// manually.
buffer_.push_back('\x02');
buffer_.push_back('\x00');
ResetContext();
return true;
}
stream_->next_in = NULL;
stream_->avail_in = 0;
int result = Deflate(Z_SYNC_FLUSH);
// Deflate returning Z_BUF_ERROR means that it's successfully flushed and
// blocked for input data.
if (result != Z_BUF_ERROR) {
ResetContext();
return false;
}
// Remove 4 octets from the tail as the specification requires.
if (CurrentOutputSize() < 4) {
ResetContext();
return false;
}
buffer_.resize(buffer_.size() - 4);
ResetContext();
return true;
}
void WebSocketDeflater::PushSyncMark() {
DCHECK(!are_bytes_added_);
const char data[] = {'\x00', '\x00', '\xff', '\xff'};
buffer_.insert(buffer_.end(), &data[0], &data[sizeof(data)]);
}
scoped_refptr<IOBufferWithSize> WebSocketDeflater::GetOutput(size_t size) {
std::deque<char>::iterator begin = buffer_.begin();
std::deque<char>::iterator end = begin + std::min(size, buffer_.size());
scoped_refptr<IOBufferWithSize> result = new IOBufferWithSize(end - begin);
std::copy(begin, end, result->data());
buffer_.erase(begin, end);
return result;
}
void WebSocketDeflater::ResetContext() {
if (mode_ == DO_NOT_TAKE_OVER_CONTEXT)
deflateReset(stream_.get());
are_bytes_added_ = false;
}
int WebSocketDeflater::Deflate(int flush) {
int result = Z_OK;
do {
stream_->next_out = reinterpret_cast<Bytef*>(&fixed_buffer_[0]);
stream_->avail_out = fixed_buffer_.size();
result = deflate(stream_.get(), flush);
size_t size = fixed_buffer_.size() - stream_->avail_out;
buffer_.insert(buffer_.end(), &fixed_buffer_[0], &fixed_buffer_[0] + size);
} while (result == Z_OK);
return result;
}
} // namespace net
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