Add RadioTapParser class

include/tins/radiotap.h

@@ -54,6 +54,11 @@ public:
      */
     static const PDU::PDUType pdu_flag = PDU::RADIOTAP;
 
+    /**
+     * RadioTap is little endian
+     */
+    static const endian_type endianness = LE;
+
     /**
      * \brief Enumeration of the different channel type flags.
      * 

include/tins/utils/radiotap_parser.h

@@ -0,0 +1,134 @@
+/*
+ * 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_PARSER_H
+#define TINS_RADIOTAP_PARSER_H
+
+#include <stdint.h>
+#include "macros.h"
+#include "radiotap.h"
+#include "pdu_option.h"
+
+namespace Tins {
+namespace Utils {
+
+struct RadioTapFlags;
+
+/**
+ * \brief Allows parsing RadioTap options
+ *
+ * RadioTap is a somehow tricky protocol to be parsed, as it has ordered flags,
+ * alignment between options, etc. This class allows parsing options in a RadioTap
+ * header without much trouble.
+ */
+class RadioTapParser {
+public:
+    /**
+     * Represents the RadioTap namespace currently being parsed
+     */
+    enum NamespaceType {
+        RADIOTAP_NS,
+        VENDOR_NS,
+        UNKNOWN_NS
+    };
+
+    typedef PDUOption<uint8_t, RadioTap> option;
+
+    /**
+     * The RadioTap header
+     */
+    TINS_BEGIN_PACK
+    struct RadiotapHeader {
+    #if TINS_IS_LITTLE_ENDIAN
+        uint8_t version; 
+        uint8_t padding;
+    #else
+        uint8_t padding;
+        uint8_t version;
+    #endif // TINS_IS_LITTLE_ENDIAN 
+        uint16_t length;
+        uint32_t flags;
+    } TINS_END_PACK;
+
+    /**
+     * \brief Constructs a RadioTap parser around a payload
+     *
+     * Note that the payload is not copied, hence it must be kept in 
+     * scope while the parser is still being used.
+     *
+     * The buffer should contain an entire RadioTap header, with optionally
+     * extra data at the end, which will be ignored.
+     *
+     * \param buffer The buffer to be parsed
+     */
+    RadioTapParser(const std::vector<uint8_t>& buffer);
+
+    /**
+     * Gets the current namespace being parsed
+     */
+    NamespaceType current_namespace() const;
+
+    /**
+     * Gets the current field being parsed
+     */
+    RadioTap::PresentFlags current_field() const;
+
+    /**
+     * Gets the option the parsed is currently pointing at
+     */
+    option current_option();
+
+    /**
+     * \brief Advances to the next option
+     *
+     * If there's a namespace change, this will handle that as well.
+     *
+     * \returns true iff advancing was successfull (e.g. false if we reached
+     * the end of the header)
+     */
+    bool advance_field();
+private:
+    const uint8_t* find_options_start() const;
+    bool advance_to_next_field(bool start_from_zero);
+    bool advance_to_next_namespace();
+    const RadioTapFlags* get_flags_ptr() const;
+    bool is_field_set(uint32_t bit, const RadioTapFlags* flags) const;
+
+    const uint8_t* start_;
+    const uint8_t* end_; 
+    const uint8_t* current_ptr_;
+    NamespaceType current_namespace_;
+    uint32_t current_bit_;
+    uint32_t namespace_index_;
+};
+
+} // Utils
+} // Tins
+
+#endif // TINS_RADIOTAP_PARSER_H