Add ICMP extensions structure class

include/tins/icmp_extension.h

@@ -2,7 +2,10 @@
 #define TINS_ICMP_EXTENSION_H
 
 #include <vector>
+#include <list>
 #include <stdint.h>
+#include "small_uint.h"
+#include "endianness.h"
 
 namespace Tins {
 
@@ -11,7 +14,15 @@ namespace Tins {
  */
 class ICMPExtension {
 public:
+    /**
+     * The type used to store the payload 
+     */
     typedef std::vector<uint8_t> payload_type;
+
+    /**
+     * The type that will be returned when serializing an extensions 
+     * structure object
+     */
     typedef std::vector<uint8_t> serialization_type;
 
     /**
@@ -50,7 +61,7 @@ public:
      *
      * \return The size of this extension
      */
-    uint32_t extension_size() const;
+    uint32_t size() const;
 
     /**
      * \brief Serializes this extension into a buffer
@@ -61,9 +72,9 @@ public:
     void serialize(uint8_t* buffer, uint32_t buffer_size) const;
 
     /**
-     * \brief Serializes this ICMP extension object
+     * \brief Serializes this extension object
      * 
-     * \return The serialized ICMP extension
+     * \return The serialized extension
      */
     serialization_type serialize() const;
 private:
@@ -73,6 +84,119 @@ private:
     uint8_t extension_class_, extension_type_;
 };
 
+/**
+ * \brief Class that represents an ICMP extensions structure
+ */
+class ICMPExtensionsStructure {
+public:
+    /**
+     * The type that will be returned when serializing an extensions 
+     * structure object
+     */
+    typedef ICMPExtension::serialization_type serialization_type;
+
+    /**
+     * The type used to store the list of ICMP extensions in this structure
+     */
+    typedef std::list<ICMPExtension> extensions_type;
+
+    /**
+     * \brief Default constructor
+     *
+     * This sets the version to 2, as specified in RFC 4884
+     */
+    ICMPExtensionsStructure();
+
+    /**
+     * \brief Constructor from a buffer.
+     *
+     * This constructor will find, parse and store the extension
+     * stack in the buffer.
+     */
+    ICMPExtensionsStructure(const uint8_t* buffer, uint32_t total_sz);
+
+    /**
+     * \brief Setter for the checksum field
+     *
+     * \param value The new reserved field value
+     */
+    void reserved(small_uint<12> value);
+
+    /**
+     * \brief Getter for the version field
+     *
+     * \return The version field value
+     */
+    small_uint<4> version() const { 
+        uint16_t value = Endian::be_to_host(version_and_reserved_);
+        return (value >> 12) & 0xf; 
+    }
+
+    /**
+     * \brief Getter for the reserved field
+     *
+     * \return The reserved field value
+     */
+    small_uint<12> reserved() const { 
+        uint16_t value = Endian::be_to_host(version_and_reserved_);
+        return value & 0xfff;
+    }
+
+    /**
+     * \brief Getter for the checksum field
+     *
+     * \return The checksum field value
+     */
+    uint16_t checksum() const { return Endian::be_to_host(checksum_); }
+
+    /**
+     * \brief Getter for the extensions stored by this structure
+     *
+     * \return The extensions stored in this structure
+     */
+    const extensions_type& extensions() const { return extensions_; }
+
+    /**
+     * \brief Gets the size of this ICMP extensions structure
+     *
+     * \return The size of this structure
+     */
+    uint32_t size() const;
+
+    /**
+     * \brief Serializes this extension structure into a buffer
+     *
+     * \param buffer The output buffer in which to store the serialization
+     * \param buffer_size The size of the output buffer
+     */
+    void serialize(uint8_t* buffer, uint32_t buffer_size);
+
+    /**
+     * \brief Serializes this extension structure
+     * 
+     * \return The serialized extension structure
+     */
+    serialization_type serialize();
+
+    /**
+     * \brief Validates if the given input contains a valid extension structure
+     *
+     * The validation is performed by calculating the checksum of the input
+     * and comparing to the checksum value in the input buffer.
+     *
+     * \param buffer The input buffer
+     * \param total_sz The size of the input buffer
+     * \return true iff the buffer contains a valid ICMP extensions structure
+     */
+    static bool validate_extensions(const uint8_t* buffer, uint32_t total_sz);
+private:
+    static const uint32_t BASE_HEADER_SIZE;
+
+    uint16_t version_and_reserved_;
+    uint16_t checksum_;
+    extensions_type extensions_;
+};
+
 } // Tins
 
 #endif // TINS_ICMP_EXTENSION_H

include/tins/utils.h

@@ -215,17 +215,30 @@ namespace Tins {
          */
         std::string to_string(PDU::PDUType pduType);
 
-        /** \brief Does the 16 bits sum of all 2 bytes elements between start and end.
+        /** 
+         * \brief Does the 16 bits sum of all 2 bytes elements between start and end.
          *
          * This is the checksum used by IP, UDP and TCP. If there's and odd number of
-         * bytes, the last one is padded and added to the checksum. The checksum is performed
-         * using network endiannes.
+         * bytes, the last one is padded and added to the checksum. 
          * \param start The pointer to the start of the buffer.
          * \param end The pointer to the end of the buffer(excluding the last element).
-         * \return Returns the checksum between start and end(non inclusive).
+         * \return Returns the checksum between start and end (non inclusive) 
+         * in network endian
          */
         uint32_t do_checksum(const uint8_t *start, const uint8_t *end);
 
+        /** 
+         * \brief Computes the 16 bit sum of the input buffer.
+         *
+         * If there's and odd number of bytes in the buffer, the last one is padded and 
+         * added to the checksum. 
+         * \param start The pointer to the start of the buffer.
+         * \param end The pointer to the end of the buffer(excluding the last element).
+         * \return Returns the checksum between start and end (non inclusive) 
+         * in network endian
+         */
+        uint16_t sum_range(const uint8_t *start, const uint8_t *end);
+
         /** \brief Performs the pseudo header checksum used in TCP and UDP PDUs.
          *
          * \param source_ip The source ip address.