per message deflate support (with zlib)

ixwebsocket/IXWebSocketPerMessageDeflate.cpp

@@ -0,0 +1,222 @@
+/*
+ *  IXWebSocketPerMessageDeflate.cpp
+ *  Author: Benjamin Sergeant
+ *  Copyright (c) 2018 Machine Zone, Inc. All rights reserved.
+ *
+ *  Per message Deflate RFC: https://tools.ietf.org/html/rfc7692
+ *
+ *  Chrome websocket -> https://github.com/chromium/chromium/tree/2ca8c5037021c9d2ecc00b787d58a31ed8fc8bcb/net/websockets
+ */
+
+#include "IXWebSocketPerMessageDeflate.h"
+#include "IXWebSocketPerMessageDeflateOptions.h"
+
+#include <iostream>
+#include <cassert>
+
+namespace
+{
+    // The passed in size (4) is important, without it the string litteral
+    // is treated as a char* and the null termination (\x00) makes it 
+    // look like an empty string.
+    const std::string kEmptyUncompressedBlock = std::string("\x00\x00\xff\xff", 4);
+
+    const int kBufferSize = 1 << 14;
+}
+
+namespace ix
+{
+    //
+    // Compressor
+    //
+    WebSocketPerMessageDeflateCompressor::WebSocketPerMessageDeflateCompressor()
+      : _compressBufferSize(kBufferSize)
+    {
+        _deflateState.zalloc = Z_NULL;
+        _deflateState.zfree = Z_NULL;
+        _deflateState.opaque = Z_NULL;
+    }
+
+    WebSocketPerMessageDeflateCompressor::~WebSocketPerMessageDeflateCompressor()
+    {
+        deflateEnd(&_deflateState);
+    }
+
+    bool WebSocketPerMessageDeflateCompressor::init(uint8_t deflateBits,
+                                                    bool client_no_context_takeover)
+    {
+        int ret = deflateInit2(
+            &_deflateState,
+            Z_DEFAULT_COMPRESSION,
+            Z_DEFLATED,
+            -1*deflateBits,
+            4, // memory level 1-9
+            Z_DEFAULT_STRATEGY
+        );
+
+        if (ret != Z_OK) return false;
+
+        _compressBuffer.reset(new unsigned char[_compressBufferSize]);
+        if (client_no_context_takeover)
+        {
+            _flush = Z_FULL_FLUSH;
+        }
+        else
+        {
+            _flush = Z_SYNC_FLUSH;
+        }
+
+        return true;
+    }
+
+    bool WebSocketPerMessageDeflateCompressor::endsWith(const std::string& value,
+                                                        const std::string& ending)
+    {
+        if (ending.size() > value.size()) return false;
+        return std::equal(ending.rbegin(), ending.rend(), value.rbegin());
+    }
+
+    bool WebSocketPerMessageDeflateCompressor::compress(const std::string& in,
+                                                        std::string& out)
+    {
+        size_t output;
+
+        if (in.empty())
+        {
+            uint8_t buf[6] = {0x02, 0x00, 0x00, 0x00, 0xff, 0xff};
+            out.append((char *)(buf), 6);
+            return true;
+        }
+
+        _deflateState.avail_in = (uInt) in.size();
+        _deflateState.next_in = (Bytef*) in.data();
+
+        do
+        {
+            // Output to local buffer
+            _deflateState.avail_out = (uInt) _compressBufferSize;
+            _deflateState.next_out = _compressBuffer.get();
+
+            deflate(&_deflateState, _flush);
+
+            output = _compressBufferSize - _deflateState.avail_out;
+
+            out.append((char *)(_compressBuffer.get()),output);
+        } while (_deflateState.avail_out == 0);
+
+        if (endsWith(out, kEmptyUncompressedBlock))
+        {
+            out.resize(out.size() - 4);
+        }
+
+        return true;
+    }
+
+    //
+    // Decompressor
+    //
+    WebSocketPerMessageDeflateDecompressor::WebSocketPerMessageDeflateDecompressor()
+      : _compressBufferSize(kBufferSize)
+    {
+        _inflateState.zalloc = Z_NULL;
+        _inflateState.zfree = Z_NULL;
+        _inflateState.opaque = Z_NULL;
+        _inflateState.avail_in = 0;
+        _inflateState.next_in = Z_NULL;
+    }
+
+    WebSocketPerMessageDeflateDecompressor::~WebSocketPerMessageDeflateDecompressor()
+    {
+        inflateEnd(&_inflateState);
+    }
+
+    bool WebSocketPerMessageDeflateDecompressor::init(uint8_t inflateBits,
+                                                      bool client_no_context_takeover)
+    {
+        int ret = inflateInit2(
+            &_inflateState,
+            -1*inflateBits
+        );
+
+        if (ret != Z_OK) return false;
+
+        _compressBuffer.reset(new unsigned char[_compressBufferSize]);
+        if (client_no_context_takeover)
+        {
+            _flush = Z_FULL_FLUSH;
+        }
+        else
+        {
+            _flush = Z_SYNC_FLUSH;
+        }
+
+        return true;
+    }
+
+    bool WebSocketPerMessageDeflateDecompressor::decompress(const std::string& in,
+                                                            std::string& out)
+    {
+        std::string inFixed(in);
+        inFixed += kEmptyUncompressedBlock;
+
+        _inflateState.avail_in = (uInt) inFixed.size();
+        _inflateState.next_in = (unsigned char *)(const_cast<char *>(inFixed.data()));
+
+        do
+        {
+            _inflateState.avail_out = (uInt) _compressBufferSize;
+            _inflateState.next_out = _compressBuffer.get();
+
+            int ret = inflate(&_inflateState, Z_SYNC_FLUSH);
+
+            if (ret == Z_NEED_DICT || ret == Z_DATA_ERROR || ret == Z_MEM_ERROR)
+            {
+                return false; // zlib error
+            }
+
+            out.append(
+                reinterpret_cast<char *>(_compressBuffer.get()),
+                _compressBufferSize - _inflateState.avail_out
+            );
+        } while (_inflateState.avail_out == 0);
+
+        return true;
+    }
+
+    WebSocketPerMessageDeflate::WebSocketPerMessageDeflate()
+    {
+        _compressor.reset(new WebSocketPerMessageDeflateCompressor());
+        _decompressor.reset(new WebSocketPerMessageDeflateDecompressor());
+    }
+
+    WebSocketPerMessageDeflate::~WebSocketPerMessageDeflate()
+    {
+        _compressor.reset();
+        _decompressor.reset();
+    }
+
+    bool WebSocketPerMessageDeflate::init(const WebSocketPerMessageDeflateOptions& perMessageDeflateOptions)
+    {
+        bool clientNoContextTakeover = 
+            perMessageDeflateOptions.getClientNoContextTakeover();
+
+        uint8_t deflateBits = perMessageDeflateOptions.getClientMaxWindowBits();
+        uint8_t inflateBits = perMessageDeflateOptions.getServerMaxWindowBits();
+
+        return _compressor->init(deflateBits, clientNoContextTakeover) && 
+               _decompressor->init(inflateBits, clientNoContextTakeover);
+    }
+
+    bool WebSocketPerMessageDeflate::compress(const std::string& in,
+                                              std::string& out)
+    {
+        return _compressor->compress(in, out);
+    }
+
+    bool WebSocketPerMessageDeflate::decompress(const std::string& in,
+                                                std::string &out)
+    {
+        return _decompressor->decompress(in, out);
+    }
+
+}