masking utility functions and unit tests

src/processors/hybi_util.cpp

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+/*
+ * Copyright (c) 2011, Peter Thorson. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * 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.
+ *     * Neither the name of the WebSocket++ Project nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 PETER THORSON 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 "hybi_util.hpp"
+
+namespace websocketpp {
+namespace processor {
+namespace hybi_util { 
+
+size_t prepare_masking_key(const masking_key_type& key) {
+    size_t prepared_key = key.i;
+    if (sizeof(size_t) == 8) {
+        prepared_key <<= 32;
+        prepared_key |= (static_cast<size_t>(key.i) & 0x00000000FFFFFFFFLL);
+    }
+    return prepared_key;
+}
+
+size_t circshift_prepared_key(size_t prepared_key, size_t offset) {
+    size_t temp = prepared_key << (sizeof(size_t)-offset)*8;
+    return (prepared_key >> offset*8) | temp;
+}
+
+void word_mask_exact(char* data,size_t length,const masking_key_type& key) {
+    size_t prepared_key = prepare_masking_key(key);
+    size_t n = length/sizeof(size_t);
+    size_t* word_data = reinterpret_cast<size_t*>(data);
+    
+    for (size_t i = 0; i < n; i++) {
+        word_data[i] ^= prepared_key;
+    }
+    
+    for (size_t i = n*sizeof(size_t); i < length; i++) {
+        data[i] ^= key.c[i%4];
+    }
+}
+
+} // namespace hybi_util
+} // namespace processor
+} // namespace websocketpp

src/processors/hybi_util.hpp

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2011, Peter Thorson. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * 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.
+ *     * Neither the name of the WebSocket++ Project nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 PETER THORSON 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.
+ * 
+ */
+
+#ifndef WEBSOCKET_HYBI_UTIL_HPP
+#define WEBSOCKET_HYBI_UTIL_HPP
+
+#include "../common.hpp"
+
+namespace websocketpp {
+namespace processor {
+namespace hybi_util {    
+
+// type used to store a masking key
+union masking_key_type {
+    int32_t i;
+    char    c[4];
+};
+
+// extract a masking key into a value the size of a machine word. Machine word
+// size must be 4 or 8
+size_t prepare_masking_key(const masking_key_type& key);
+
+// circularly shifts the supplied prepared masking key by offset bytes
+// prepared_key must be the output of prepare_masking_key with the associated
+//    restrictions on the machine word size.
+// offset must be 0, 1, 2, or 3
+size_t circshift_prepared_key(size_t prepared_key, size_t offset);
+
+// basic byte by byte mask
+template <typename iter_type>
+void byte_mask(iter_type b, iter_type e, const masking_key_type& key, size_t key_offset = 0) {
+    size_t key_index = key_offset;
+    for (iter_type i = b; i != e; i++) {
+        *i ^= key.c[key_index++];
+        key_index %= 4;
+    }
+}
+
+// exactly masks the bytes from start to end using key `key`
+void word_mask_exact(char* data,size_t length,const masking_key_type& key);
+
+} // namespace hybi_util
+} // namespace processor
+} // namespace websocketpp
+
+#endif // WEBSOCKET_HYBI_UTIL_HPP