277 lines
9.7 KiB
C++
277 lines
9.7 KiB
C++
/*
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* Copyright (c) 2015, Peter Thorson. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the WebSocket++ Project nor the
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* names of its contributors may be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL PETER THORSON BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Author: Benjamin Sergeant
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* Copyright (c) 2018 Machine Zone, Inc. All rights reserved.
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*
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* Adapted from websocketpp/extensions/permessage_deflate/enabled.hpp
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* (same license as MZ: https://opensource.org/licenses/BSD-3-Clause)
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*
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* - Reused zlib compression + decompression bits.
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* - Refactored to have 2 class for compression and decompression, to allow multi-threading
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* and make sure that _compressBuffer is not shared between threads.
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* - Original code wasn't working for some reason, I had to add checks
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* for the presence of the kEmptyUncompressedBlock at the end of buffer so that servers
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* would start accepting receiving/decoding compressed messages. Original code was probably
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* modifying the passed in buffers before processing in enabled.hpp ?
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* - Added more documentation.
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*
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* Per message Deflate RFC: https://tools.ietf.org/html/rfc7692
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* Chrome websocket -> https://github.com/chromium/chromium/tree/2ca8c5037021c9d2ecc00b787d58a31ed8fc8bcb/net/websockets
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*
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*/
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#include "IXWebSocketPerMessageDeflate.h"
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#include "IXWebSocketPerMessageDeflateOptions.h"
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#include <iostream>
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#include <cassert>
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namespace
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{
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// The passed in size (4) is important, without it the string litteral
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// is treated as a char* and the null termination (\x00) makes it
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// look like an empty string.
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const std::string kEmptyUncompressedBlock = std::string("\x00\x00\xff\xff", 4);
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const int kBufferSize = 1 << 14;
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}
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namespace ix
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{
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//
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// Compressor
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//
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WebSocketPerMessageDeflateCompressor::WebSocketPerMessageDeflateCompressor()
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: _compressBufferSize(kBufferSize)
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{
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_deflateState.zalloc = Z_NULL;
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_deflateState.zfree = Z_NULL;
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_deflateState.opaque = Z_NULL;
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}
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WebSocketPerMessageDeflateCompressor::~WebSocketPerMessageDeflateCompressor()
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{
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deflateEnd(&_deflateState);
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}
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bool WebSocketPerMessageDeflateCompressor::init(uint8_t deflateBits,
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bool clientNoContextTakeOver)
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{
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int ret = deflateInit2(
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&_deflateState,
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Z_DEFAULT_COMPRESSION,
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Z_DEFLATED,
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-1*deflateBits,
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4, // memory level 1-9
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Z_DEFAULT_STRATEGY
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);
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if (ret != Z_OK) return false;
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_compressBuffer.reset(new unsigned char[_compressBufferSize]);
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_flush = (clientNoContextTakeOver)
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? Z_FULL_FLUSH
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: Z_SYNC_FLUSH;
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return true;
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}
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bool WebSocketPerMessageDeflateCompressor::endsWith(const std::string& value,
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const std::string& ending)
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{
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if (ending.size() > value.size()) return false;
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return std::equal(ending.rbegin(), ending.rend(), value.rbegin());
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}
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bool WebSocketPerMessageDeflateCompressor::compress(const std::string& in,
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std::string& out)
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{
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//
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// 7.2.1. Compression
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//
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// An endpoint uses the following algorithm to compress a message.
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//
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// 1. Compress all the octets of the payload of the message using
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// DEFLATE.
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//
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// 2. If the resulting data does not end with an empty DEFLATE block
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// with no compression (the "BTYPE" bits are set to 00), append an
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// empty DEFLATE block with no compression to the tail end.
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//
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// 3. Remove 4 octets (that are 0x00 0x00 0xff 0xff) from the tail end.
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// After this step, the last octet of the compressed data contains
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// (possibly part of) the DEFLATE header bits with the "BTYPE" bits
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// set to 00.
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//
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size_t output;
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if (in.empty())
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{
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uint8_t buf[6] = {0x02, 0x00, 0x00, 0x00, 0xff, 0xff};
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out.append((char *)(buf), 6);
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return true;
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}
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_deflateState.avail_in = (uInt) in.size();
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_deflateState.next_in = (Bytef*) in.data();
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do
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{
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// Output to local buffer
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_deflateState.avail_out = (uInt) _compressBufferSize;
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_deflateState.next_out = _compressBuffer.get();
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deflate(&_deflateState, _flush);
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output = _compressBufferSize - _deflateState.avail_out;
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out.append((char *)(_compressBuffer.get()),output);
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} while (_deflateState.avail_out == 0);
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if (endsWith(out, kEmptyUncompressedBlock))
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{
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out.resize(out.size() - 4);
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}
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return true;
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}
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//
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// Decompressor
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//
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WebSocketPerMessageDeflateDecompressor::WebSocketPerMessageDeflateDecompressor()
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: _compressBufferSize(kBufferSize)
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{
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_inflateState.zalloc = Z_NULL;
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_inflateState.zfree = Z_NULL;
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_inflateState.opaque = Z_NULL;
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_inflateState.avail_in = 0;
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_inflateState.next_in = Z_NULL;
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}
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WebSocketPerMessageDeflateDecompressor::~WebSocketPerMessageDeflateDecompressor()
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{
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inflateEnd(&_inflateState);
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}
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bool WebSocketPerMessageDeflateDecompressor::init(uint8_t inflateBits,
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bool clientNoContextTakeOver)
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{
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int ret = inflateInit2(
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&_inflateState,
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-1*inflateBits
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);
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if (ret != Z_OK) return false;
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_compressBuffer.reset(new unsigned char[_compressBufferSize]);
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_flush = (clientNoContextTakeOver)
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? Z_FULL_FLUSH
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: Z_SYNC_FLUSH;
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return true;
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}
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bool WebSocketPerMessageDeflateDecompressor::decompress(const std::string& in,
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std::string& out)
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{
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//
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// 7.2.2. Decompression
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//
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// An endpoint uses the following algorithm to decompress a message.
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//
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// 1. Append 4 octets of 0x00 0x00 0xff 0xff to the tail end of the
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// payload of the message.
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//
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// 2. Decompress the resulting data using DEFLATE.
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//
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std::string inFixed(in);
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inFixed += kEmptyUncompressedBlock;
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_inflateState.avail_in = (uInt) inFixed.size();
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_inflateState.next_in = (unsigned char *)(const_cast<char *>(inFixed.data()));
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do
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{
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_inflateState.avail_out = (uInt) _compressBufferSize;
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_inflateState.next_out = _compressBuffer.get();
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int ret = inflate(&_inflateState, Z_SYNC_FLUSH);
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if (ret == Z_NEED_DICT || ret == Z_DATA_ERROR || ret == Z_MEM_ERROR)
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{
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return false; // zlib error
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}
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out.append(
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reinterpret_cast<char *>(_compressBuffer.get()),
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_compressBufferSize - _inflateState.avail_out
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);
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} while (_inflateState.avail_out == 0);
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return true;
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}
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WebSocketPerMessageDeflate::WebSocketPerMessageDeflate()
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{
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_compressor.reset(new WebSocketPerMessageDeflateCompressor());
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_decompressor.reset(new WebSocketPerMessageDeflateDecompressor());
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}
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WebSocketPerMessageDeflate::~WebSocketPerMessageDeflate()
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{
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_compressor.reset();
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_decompressor.reset();
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}
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bool WebSocketPerMessageDeflate::init(const WebSocketPerMessageDeflateOptions& perMessageDeflateOptions)
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{
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bool clientNoContextTakeover =
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perMessageDeflateOptions.getClientNoContextTakeover();
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uint8_t deflateBits = perMessageDeflateOptions.getClientMaxWindowBits();
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uint8_t inflateBits = perMessageDeflateOptions.getServerMaxWindowBits();
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return _compressor->init(deflateBits, clientNoContextTakeover) &&
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_decompressor->init(inflateBits, clientNoContextTakeover);
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}
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bool WebSocketPerMessageDeflate::compress(const std::string& in,
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std::string& out)
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{
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return _compressor->compress(in, out);
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}
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bool WebSocketPerMessageDeflate::decompress(const std::string& in,
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std::string &out)
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{
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return _decompressor->decompress(in, out);
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}
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}
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