Add RadioTapWriter class

include/tins/utils/radiotap_writer.h

@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2017, Matias Fontanini
+ * 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.
+ *
+ * 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 THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS 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 TINS_RADIOTAP_WRITER_H
+#define TINS_RADIOTAP_WRITER_H
+
+#include <vector>
+#include <stdint.h>
+#include "radiotap_parser.h"
+
+namespace Tins {
+namespace Utils {
+
+/**
+ * \brief Writes RadioTap options into a buffer
+ *
+ * This class can write RadioTap options into a buffer, respecting the alignment
+ * of each of them.
+ *
+ * Note that RadioTap options are ordered. Writing multiple of them in a non
+ * ascending order will involve several memory moves around the buffer so it
+ * will be less efficient.
+ */
+class RadioTapWriter {
+public:
+    /**
+     * \brief Constructs a RadioTapWriter object
+     * 
+     * Note that a reference to the buffer will be kept and updated so it must
+     * be kept in scope while writing options to it
+     */
+    RadioTapWriter(std::vector<uint8_t>& buffer);
+
+    /**
+     * \brief Writes an option, adding/removing padding as needed
+     *
+     * The function returns true iff the option was added successfully. This will
+     * always be the case, unless an option having that type is already set.
+     *
+     * \param option The option to be written
+     */
+    bool write_option(const RadioTapParser::option& option);
+private:
+    std::vector<uint8_t> build_padding_vector(const uint8_t* last_ptr, RadioTapParser& parser);
+    void update_paddings(const std::vector<uint8_t>& paddings, uint32_t offset);
+
+    std::vector<uint8_t>& buffer_;
+};
+
+} // Utils
+} // Tins
+
+#endif // TINS_RADIOTAP_WRITER_H