/src/PcapPlusPlus/Packet++/header/DnsResourceData.h

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#pragma once

#include "DnsResource.h"
#include "IpAddress.h"
#include <memory>
#include <string>
#include <stdint.h>

/// @file

/**
 * \namespace pcpp
 * \brief The main namespace for the PcapPlusPlus lib
 */
namespace pcpp
{

  //Visual studio has always been stupid about returning something useful for __cplusplus
  //Only recently was this fixed - and even then it requires a specific hack to the command line during build
  //Its easier/more consistent to test _MSC_VER in VS
  //https://docs.microsoft.com/en-us/cpp/build/reference/zc-cplusplus?view=vs-2017

  #if __cplusplus > 199711L || _MSC_VER >= 1800 //Maybe this can be 1600 for VS2010
  #define PCPP_SMART_PTR(T) std::unique_ptr<T>
  #else
  #define PCPP_SMART_PTR(T) std::auto_ptr<T>
  #endif

  // forward declarations
  class IDnsResource;

  /**
   * @class IDnsResourceData
   * A wrapper class for storing DNS RR (resource record) data. This is the base class which introduces several abstract
   * methods for derived classes to implement for setting and retrieving the stored data. Each derived class will store
   * different type of DNS RR data and implement these methods accordingly (for example: IPv4/IPv6 addresses, MX data,
   * hostnames, raw byte data etc.)
   */
  class IDnsResourceData
  {
  protected:

    // unimplemented private copy c'tor
    IDnsResourceData(const IDnsResourceData& other);
    IDnsResourceData() { }

    size_t decodeName(const char* encodedName, char* result, IDnsResource* dnsResource) const;
    void encodeName(const std::string& decodedName, char* result, size_t& resultLen, IDnsResource* dnsResource) const;

  public:
    /**
     * A virtual d'tor, does nothing
     */
    virtual ~IDnsResourceData() { }

    /**
     * A templated method which takes a class that derives from IDnsResourceData as the template argument and
     * checks whether this instance is of this type
     * @return True if this instance is of the requested type, false otherwise
     */
    template <class IDnsResourceDataType>
    bool isTypeOf() const { return dynamic_cast<const IDnsResourceDataType*>(this) != NULL; }

    /**
     * A templated method which take a class that derives from IDnsResourceData as the template argument and tries to
     * cast the current instance as that type
     * @return A pointer to the current instance casted as the requested type or NULL if this instance isn't of this type
     */
    template <class IDnsResourceDataType>
    IDnsResourceDataType* castAs() { return dynamic_cast<IDnsResourceDataType*>(this); }

    /**
     * @return A string that represents the current DNS RR data
     */
    virtual std::string toString() const = 0;

    /**
     * Convert the DNS RR data into a byte array
     * @param[out] arr A pointer to a pre-allocated byte array where the result will be written to
     * @param[out] arrLength A reference to a 2-byte number where the result array length will be written to
     * @param[in] dnsResource A pointer to a DNS resource object where this DNS RR data will be stored
     * @return True if the DNS RR data was successfully converted into a byte array and written to the given array or
     * false if stored DNS RR data is invalid or if it could not be written to the given array
     */
    virtual bool toByteArr(uint8_t* arr, size_t& arrLength, IDnsResource* dnsResource) const = 0;
  };


  /**
   * @class DnsResourceDataPtr
   * A smart pointer class that holds pointers of type IDnsResourceData. This object is used in DnsResource#getData()
   */
  class DnsResourceDataPtr : public PCPP_SMART_PTR(IDnsResourceData)
  {
  public:

    /**
     * A c'tor to this class
     * @param[in] ptr A pointer to IDnsResourceData
     */
    explicit DnsResourceDataPtr(IDnsResourceData* ptr) : PCPP_SMART_PTR(IDnsResourceData)(ptr) {}

    //Visual studio has always been stupid about returning something useful for __cplusplus
    //Only recently was this fixed - and even then it requires a specific hack to the command line during build
    //Its easier/more consistent to test _MSC_VER in VS
    //https://docs.microsoft.com/en-us/cpp/build/reference/zc-cplusplus?view=vs-2017

#if __cplusplus <= 199711L && _MSC_VER < 1800 //Maybe this can be 1600 for VS2010
    DnsResourceDataPtr(const DnsResourceDataPtr& other) : PCPP_SMART_PTR(IDnsResourceData)((DnsResourceDataPtr&)other) {}
#endif

    /**
     * A templated method which takes a class that derives from IDnsResourceData as the template argument and
     * checks whether the pointer stored in this object is of this type
     * @return True if the stored pointer is of the requested type, false otherwise
     */
    template <class IDnsResourceDataType>
    bool isTypeOf() const { return get()->isTypeOf<IDnsResourceDataType>(); }

    /**
     * A templated method which take a class that derives from IDnsResourceData as the template argument and tries to
     * cast the pointer stored in this object as that type
     * @return A pointer to the stored pointer casted as the requested type or NULL if it isn't of this type
     */
    template <class IDnsResourceDataType>
    IDnsResourceDataType* castAs() { return get()->castAs<IDnsResourceDataType>();}
  };


  /**
   * @class StringDnsResourceData
   * A class that represents DNS RR string data, mainly used in DNS RRs that store hostnames (like CNAME, DNAME, NS, etc.)
   */
  class StringDnsResourceData : public IDnsResourceData
  {
  private:
    std::string m_Data;

  public:

    /**
     * A c'tor for this class
     * @param[in] data The string data to store in this object. If this string represents a hostname it's possible
     * to include a pointer to another string in the DNS layer (as explained here: http://www.zytrax.com/books/dns/ch15/#name).
     * These pointers are often used to reduce the DNS packet size and avoid unnecessary duplications. The way to include pointers
     * in a hostname string is to use the following format: 'some.domain.#{offset}' where '#{offset}' is the offset from the
     * start of the DNS layer. For example: if the string 'yahoo.com' already appears in offset 12 in the packet and you want
     * to set the DNS RR data as 'my.subdomain.yahoo.com' you may use the following string: 'my.subdomain.#12'.
     * This will result in writing 'my.subdomain' and a pointer to offset 12
     */
    explicit StringDnsResourceData(const std::string& data) : m_Data(data) {}

    StringDnsResourceData(const uint8_t* dataPtr, size_t dataLen, IDnsResource* dnsResource);

    ~StringDnsResourceData() {}

    /**
     * Equality operator overload for this class that compares the strings stored in each object
     * @param[in] other The object to compare with
     * @return True if the string data is the same in both objects, false otherwise
     */
    bool operator==(const StringDnsResourceData& other) const { return m_Data == other.m_Data; }

    // implement abstract methods

    std::string toString() const { return m_Data; }
    bool toByteArr(uint8_t* arr, size_t& arrLength, IDnsResource* dnsResource) const;
  };


  /**
   * @class IPv4DnsResourceData
   * A class that represents DNS RR IPv4 data, mainly used in DNS RRs of type ::DNS_TYPE_A
   */
  class IPv4DnsResourceData : public IDnsResourceData
  {
  private:
    IPv4Address m_Data;

  public:

    /**
     * A c'tor for this class
     * @param[in] dataPtr A byte array of size 4 that contains an IPv4 address (each byte represents 1 octet)
     * @param[in] dataLen The byte array size, expected to be 4
     */
    IPv4DnsResourceData(const uint8_t* dataPtr, size_t dataLen);

    /**
     * A c'tor for this class
     * @param[in] addr The IPv4 address to store in this object
     */
    explicit IPv4DnsResourceData(const IPv4Address& addr) : m_Data(addr) {}

    /**
     * A c'tor for this class
     * @param[in] addrAsString A string representation of an IPv4 address to store in this object
     */
    explicit IPv4DnsResourceData(const std::string& addrAsString) : m_Data(addrAsString) {}

    /**
     * Equality operator overload for this class that compares the IPv4 addresses stored in each object
     * @param[in] other The object to compare with
     * @return True if IPv4 addresses are the same in both objects, false otherwise
     */
    bool operator==(const IPv4DnsResourceData& other) const { return m_Data == other.m_Data; }

    /**
     * @return The IPv4 address stored in this object
     */
    IPv4Address getIpAddress() const { return m_Data; }

    // implement abstract methods

    std::string toString() const { return m_Data.toString(); }
    bool toByteArr(uint8_t* arr, size_t& arrLength, IDnsResource* dnsResource) const;
  };


  /**
   * @class IPv6DnsResourceData
   * A class that represents DNS RR IPv6 data, mainly used in DNS RRs of type ::DNS_TYPE_AAAA
   */
  class IPv6DnsResourceData : public IDnsResourceData
  {
  private:
    IPv6Address m_Data;

  public:

    /**
     * A c'tor for this class
     * @param[in] dataPtr A byte array of size 16 that contains an IPv6 address (each byte represents 1 octet)
     * @param[in] dataLen The byte array size, expected to be 16
     */
    IPv6DnsResourceData(const uint8_t* dataPtr, size_t dataLen);

    /**
     * A c'tor for this class
     * @param[in] addr The IPv6 address to store in this object
     */
    explicit IPv6DnsResourceData(const IPv6Address& addr) : m_Data(addr) {}

    /**
     * A c'tor for this class
     * @param[in] addrAsString A string representation of an IPv6 address to store in this object
     */
    explicit IPv6DnsResourceData(const std::string& addrAsString) : m_Data(addrAsString) {}

    /**
     * Equality operator overload for this class that compares the IPv6 addresses stored in each object
     * @param[in] other The object to compare with
     * @return True if IPv6 addresses are the same in both objects, false otherwise
     */
    bool operator==(const IPv6DnsResourceData& other) const { return m_Data == other.m_Data; }

    /**
     * @return The IPv6 address stored in this object
     */
    IPv6Address getIpAddress() const { return m_Data; }

    // implement abstract methods

    std::string toString() const { return m_Data.toString(); }
    bool toByteArr(uint8_t* arr, size_t& arrLength, IDnsResource* dnsResource) const;
  };


  /**
   * @class MxDnsResourceData
   * A class that represents DNS RR mail exchange (MX) data, used in DNS RRs of type ::DNS_TYPE_MX
   */
  class MxDnsResourceData : public IDnsResourceData
  {
  public:

    /**
     * A struct that represents mail exchange (MX) data
     */
    struct MxData
    {
      /** Preference value */
      uint16_t preference;
      /** Mail exchange hostname */
      std::string mailExchange;
    };

    /**
     * A c'tor for this class
     * @param[in] dataPtr A byte array that contains the raw MX data (as written in the DNS packet)
     * @param[in] dataLen The byte array size
     * @param[in] dnsResource A pointer to a DNS resource object where this DNS RR data will be stored
     */
    MxDnsResourceData(uint8_t* dataPtr, size_t dataLen, IDnsResource* dnsResource);

    /**
     * A c'tor for this class
     * @param[in] preference The MX preference value to store in this object
     * @param[in] mailExchange The MX hostname value to store in this object. It's possible to include a pointer to
     * another string in the DNS layer (as explained here: http://www.zytrax.com/books/dns/ch15/#name). These pointers
     * are often used to reduce the DNS packet size and avoid unnecessary duplications. The way to include pointers
     * in the hostname string is to use the following format: 'some.domain.#{offset}' where '#{offset}' is the offset
     * from the start of the DNS layer. For example: if the string 'yahoo.com' already appears in offset 12 in the
     * packet and you want to set the DNS RR data as 'my.subdomain.yahoo.com' you may use the following string:
     * 'my.subdomain.#12'. This will result in writing 'my.subdomain' and a pointer to offset 12
     */
    MxDnsResourceData(const uint16_t& preference, const std::string& mailExchange);

    ~MxDnsResourceData() {}

    /**
     * Equality operator overload for this class that compares the MX data stored in each object
     * @param[in] other The object to compare with
     * @return True if MX data is the same in both objects, meaning both preference and MX hostname are the same,
     * false otherwise
     */
    bool operator==(const MxDnsResourceData& other) const;

    /**
     * @return The MX data stored in this object
     */
    MxData getMxData() const { return m_Data; }

    /**
     * Set the MX data stored in this object
     * @param[in] preference The MX preference value to store in this object
     * @param[in] mailExchange The MX hostname value to store in this object
     */
    void setMxData(uint16_t preference, std::string mailExchange);

    // implement abstract methods

    /**
     * A string representation of the MX data stored in this object. The string format is as follows:
     * 'pref: {preference_value}; mx: {mail_exchange_hostname_value}'
     */
    std::string toString() const;

    bool toByteArr(uint8_t* arr, size_t& arrLength, IDnsResource* dnsResource) const;

  private:
    MxData m_Data;
  };


  /**
   * @class GenericDnsResourceData
   * A class that represents generic DNS RR data which cannot be represented in any of the other classes. It stores the
   * DNS RR data as byte array
   */
  class GenericDnsResourceData : public IDnsResourceData
  {
  private:
    uint8_t* m_Data;
    size_t m_DataLen;

  public:

    /**
     * A c'tor for this class
     * @param[in] dataPtr A byte array that contains the raw data (as it written in the DNS packet). The data will be
     * copied from this byte array to the object
     * @param[in] dataLen The byte array size
     */
    GenericDnsResourceData(const uint8_t* dataPtr, size_t dataLen);

    /**
     * A c'tor for this class
     * @param[in] dataAsHexString A hex string that represents the DNS RR data
     */
    explicit GenericDnsResourceData(const std::string& dataAsHexString);

    /**
     * A copy c'tor for this class
     * @param[in] other The instance to copy from
     */
    GenericDnsResourceData(const GenericDnsResourceData& other);

    ~GenericDnsResourceData() { if (m_Data != NULL) delete [] m_Data; }

    GenericDnsResourceData& operator=(const GenericDnsResourceData& other);

    /**
     * Equality operator overload for this class that compares the raw data stored in each object
     * @param[in] other The object to compare with
     * @return True if data is the same in both objects, meaning byte streams are equal, false otherwise
     */
    bool operator==(const GenericDnsResourceData& other) const;

    // implement abstract methods

    std::string toString() const;
    bool toByteArr(uint8_t* arr, size_t& arrLength, IDnsResource* dnsResource) const;
  };

}

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Created: 2024-02-25 06:29