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

Source
#pragma once

#include "Layer.h"
#include "IpAddress.h"
#include <string.h>

/// @file

/// @namespace pcpp
/// @brief The main namespace for the PcapPlusPlus lib
namespace pcpp
{
  /// @class TLVRecord
  /// A wrapper class for a Type-Length-Value (TLV) record. This class does not create or modify TLV records, but
  /// rather serves as a wrapper and provides useful methods for retrieving data from them. This class has several
  /// abstract methods that should be implemented in derived classes. These methods are for record length value
  /// calculation (the 'L' in TLV) which is implemented differently in different protocols
  template <typename TRecType, typename TRecLen> class TLVRecord
  {
  protected:
    /// A struct representing the TLV construct
#pragma pack(push, 1)
    struct TLVRawData
    {
      /// Record type
      TRecType recordType;
      /// Record length in bytes
      TRecLen recordLen;
      /// Record value (variable size)
      uint8_t recordValue[];
    };
#pragma pack(pop)

    TLVRawData* m_Data;

  public:
    /// A c'tor for this class that gets a pointer to the TLV record raw data (byte array)
    /// @param[in] recordRawData A pointer to the TLV record raw data
    TLVRecord(uint8_t* recordRawData)
    {
      assign(recordRawData);
    }

    /// A copy c'tor for this class. This copy c'tor doesn't copy the TLV data, but only the pointer to it,
    /// which means that after calling it both the old and the new instance will point to the same TLV raw data
    /// @param[in] other The TLVRecord instance to copy from
    TLVRecord(const TLVRecord& other)
    {
      m_Data = other.m_Data;
    }

    /// A d'tor for this class, currently does nothing
    virtual ~TLVRecord() = default;

    /// Assign a pointer to the TLV record raw data (byte array)
    /// @param[in] recordRawData A pointer to the TLV record raw data
    void assign(uint8_t* recordRawData)
    {
      m_Data = reinterpret_cast<TLVRawData*>(recordRawData);
    }

    /// Check if a pointer can be assigned to the TLV record data
    /// @param[in] recordRawData A pointer to the TLV record raw data
    /// @param[in] tlvDataLen The size of the TLV record raw data
    /// @return True if data is valid and can be assigned
    static bool canAssign(const uint8_t* recordRawData, size_t tlvDataLen)
    {
      return recordRawData != nullptr &&
             tlvDataLen >= (sizeof(TLVRawData::recordType) + sizeof(TLVRawData::recordLen));
    }

    /// Overload of the assignment operator. This operator doesn't copy the TLV data, but rather copies the pointer
    /// to it, which means that after calling it both the old and the new instance will point to the same TLV raw
    /// data
    /// @param[in] other The TLVRecord instance to assign
    TLVRecord& operator=(const TLVRecord& other)
    {
      m_Data = other.m_Data;
      return *this;
    }

    /// Overload of the equality operator. Two record are equal if both of them point to the same data, or if they
    /// point to different data but their total size is equal and the raw data they both contain is similar.
    /// @param[in] rhs The object to compare to
    /// @return True if both objects are equal, false otherwise
    bool operator==(const TLVRecord& rhs) const
    {
      if (m_Data == rhs.m_Data)
        return true;

      if (getTotalSize() != rhs.getTotalSize())
        return false;

      if (isNull() || ((TLVRecord&)rhs).isNull())
        return false;

      return (memcmp(m_Data, rhs.m_Data, getTotalSize()) == 0);
    }

    /// Overload of the not equal operator.
    /// @param[in] rhs The object to compare to
    /// @return True if objects are not equal, false otherwise
    bool operator!=(const TLVRecord& rhs) const
    {
      return !operator==(rhs);
    }

    /// @return The type field of the record (the 'T' in __Type__-Length-Value)
    TRecType getType() const
    {
      if (m_Data == nullptr)
        return 0;

      return m_Data->recordType;
    }

    /// @return A pointer to the value of the record as byte array (the 'V' in Type-Length- __Value__)
    uint8_t* getValue() const
    {
      if (m_Data == nullptr)
        return nullptr;

      return m_Data->recordValue;
    }

    /// @return True if the TLV record raw data is nullptr, false otherwise
    bool isNull() const
    {
      return (m_Data == nullptr);
    }

    /// @return True if the TLV record raw data is not nullptr, false otherwise
    bool isNotNull() const
    {
      return (m_Data != nullptr);
    }

    /// @return A pointer to the TLV record raw data byte stream
    uint8_t* getRecordBasePtr() const
    {
      return reinterpret_cast<uint8_t*>(m_Data);
    }

    /// Free the memory of the TLV record raw data
    void purgeRecordData()
    {
      if (!isNull())
      {
        delete[] m_Data;
        m_Data = nullptr;
      }
    }

    /// A templated method to retrieve the record data as a certain type T. For example, if record data is 4B long
    /// (integer) then this method should be used as getValueAs<int>() and it will return the record data as an
    /// integer.<BR> Notice this return value is a copy of the data, not a pointer to the actual data
    /// @param[in] offset The offset in the record data to start reading the value from. Useful for cases when you
    /// want to read some of the data that doesn't start at offset 0. This is an optional parameter and the default
    /// value is 0, meaning start reading the value at the beginning of the record data
    /// @return The record data as type T
    template <typename T> T getValueAs(size_t offset = 0) const
    {
      if (getDataSize() - offset < sizeof(T))
        return 0;

      T result;
      memcpy(&result, m_Data->recordValue + getValueOffset() + offset, sizeof(T));
      return result;
    }

    /// A templated method to copy data of type T into the TLV record data. For example: if record data is 4[Bytes]
    /// long use this method with \<int\> to set an integer value into the record data: setValue<int>(num)
    /// @param[in] newValue The value of type T to copy to the record data
    /// @param[in] valueOffset An optional parameter that specifies where to start setting the record data (default
    /// set to 0). For example: if record data is 20 bytes long and you only need to set the 4 last bytes as integer
    /// then use this method like this: setValue<int>(num, 16)
    /// @return True if value was set successfully or false if the size of T is larger than the record data size
    template <typename T> bool setValue(T newValue, int valueOffset = 0)
    {
      if (getDataSize() < sizeof(T))
        return false;

      memcpy(m_Data->recordValue + getValueOffset() + valueOffset, &newValue, sizeof(T));
      return true;
    }

    /// @return The total size of the TLV record (in bytes)
    virtual size_t getTotalSize() const = 0;

    /// @return The size of the record value (meaning the size of the 'V' part in TLV)
    virtual size_t getDataSize() const = 0;

  protected:
    virtual size_t getValueOffset() const
    {
      return 0;
    }
  };

  /// @class TLVRecordReader
  /// A class for reading TLV records data out of a byte stream. This class contains helper methods for retrieving and
  /// counting TLV records. This is a template class that expects template argument class derived from TLVRecord.
  template <typename TLVRecordType> class TLVRecordReader
  {
  private:
    mutable size_t m_RecordCount;

  public:
    /// A default c'tor for this class
    TLVRecordReader()
    {
      m_RecordCount = static_cast<size_t>(-1);
    }

    /// A default copy c'tor for this class
    TLVRecordReader(const TLVRecordReader& other)
    {
      m_RecordCount = other.m_RecordCount;
    }

    /// A d'tor for this class which currently does nothing
    virtual ~TLVRecordReader() = default;

    /// Overload of the assignment operator for this class
    /// @param[in] other The TLVRecordReader instance to assign
    TLVRecordReader& operator=(const TLVRecordReader& other)
    {
      m_RecordCount = other.m_RecordCount;
      return *this;
    }

    /// Get the first TLV record out of a byte stream
    /// @param[in] tlvDataBasePtr A pointer to the TLV data byte stream
    /// @param[in] tlvDataLen The TLV data byte stream length
    /// @return An instance of type TLVRecordType that contains the first TLV record. If tlvDataBasePtr is nullptr
    /// or tlvDataLen is zero the returned TLVRecordType instance will be logically null, meaning
    /// TLVRecordType.isNull() will return true
    TLVRecordType getFirstTLVRecord(uint8_t* tlvDataBasePtr, size_t tlvDataLen) const
    {
      TLVRecordType resRec(nullptr);  // for NRVO optimization
      if (!TLVRecordType::canAssign(tlvDataBasePtr, tlvDataLen))
        return resRec;

      resRec.assign(tlvDataBasePtr);
      // resRec pointer is out-bounds of the TLV records memory
      if (resRec.getRecordBasePtr() + resRec.getTotalSize() > tlvDataBasePtr + tlvDataLen)
        resRec.assign(nullptr);

      // check if there are records at all and the total size is not zero
      if (!resRec.isNull() && (tlvDataLen == 0 || resRec.getTotalSize() == 0))
        resRec.assign(nullptr);

      return resRec;
    }

    /// Get a TLV record that follows a given TLV record in a byte stream
    /// @param[in] record A given TLV record
    /// @param[in] tlvDataBasePtr A pointer to the TLV data byte stream
    /// @param[in] tlvDataLen The TLV data byte stream length
    /// @return An instance of type TLVRecordType that wraps the record following the record given as input. If the
    /// input record.isNull() is true or if the next record is out of bounds of the byte stream, a logical null
    /// instance of TLVRecordType will be returned, meaning TLVRecordType.isNull() will return true
    TLVRecordType getNextTLVRecord(TLVRecordType& record, const uint8_t* tlvDataBasePtr, size_t tlvDataLen) const
    {
      TLVRecordType resRec(nullptr);  // for NRVO optimization

      if (record.isNull())
        return resRec;

      if (!TLVRecordType::canAssign(record.getRecordBasePtr() + record.getTotalSize(),
                                    tlvDataBasePtr - record.getRecordBasePtr() + tlvDataLen -
                                        record.getTotalSize()))
        return resRec;

      resRec.assign(record.getRecordBasePtr() + record.getTotalSize());

      if (resRec.getTotalSize() == 0)
        resRec.assign(nullptr);

      // resRec pointer is out-bounds of the TLV records memory
      if ((resRec.getRecordBasePtr() - tlvDataBasePtr) < 0)
        resRec.assign(nullptr);

      // resRec pointer is out-bounds of the TLV records memory
      if (!resRec.isNull() && resRec.getRecordBasePtr() + resRec.getTotalSize() > tlvDataBasePtr + tlvDataLen)
        resRec.assign(nullptr);

      return resRec;
    }

    /// Search for the first TLV record that corresponds to a given record type (the 'T' in __Type__-Length-Value)
    /// @param[in] recordType The record type to search for
    /// @param[in] tlvDataBasePtr A pointer to the TLV data byte stream
    /// @param[in] tlvDataLen The TLV data byte stream length
    /// @return An instance of type TLVRecordType that contains the result record. If record was not found a logical
    /// null instance of TLVRecordType will be returned, meaning TLVRecordType.isNull() will return true
    TLVRecordType getTLVRecord(uint32_t recordType, uint8_t* tlvDataBasePtr, size_t tlvDataLen) const
    {
      TLVRecordType curRec = getFirstTLVRecord(tlvDataBasePtr, tlvDataLen);
      while (!curRec.isNull())
      {
        if (curRec.getType() == recordType)
        {
          return curRec;
        }

        curRec = getNextTLVRecord(curRec, tlvDataBasePtr, tlvDataLen);
      }

      curRec.assign(nullptr);
      return curRec;  // for NRVO optimization
    }

    /// Get the TLV record count in a given TLV data byte stream. For efficiency purposes the count is being cached
    /// so only the first call to this method will go over all the TLV records, while all consequent calls will
    /// return the cached number. This implies that if there is a change in the number of records, it's the user's
    /// responsibility to call changeTLVRecordCount() with the record count change
    /// @param[in] tlvDataBasePtr A pointer to the TLV data byte stream
    /// @param[in] tlvDataLen The TLV data byte stream length
    /// @return The TLV record count
    size_t getTLVRecordCount(uint8_t* tlvDataBasePtr, size_t tlvDataLen) const
    {
      if (m_RecordCount != static_cast<size_t>(-1))
        return m_RecordCount;

      m_RecordCount = 0;
      TLVRecordType curRec = getFirstTLVRecord(tlvDataBasePtr, tlvDataLen);
      while (!curRec.isNull())
      {
        m_RecordCount++;
        curRec = getNextTLVRecord(curRec, tlvDataBasePtr, tlvDataLen);
      }

      return m_RecordCount;
    }

    /// As described in getTLVRecordCount(), the TLV record count is being cached for efficiency purposes. So if the
    /// number of TLV records change, it's the user's responsibility to call this method with the number of TLV
    /// records being added or removed. If records were added the change should be a positive number, or a negative
    /// number if records were removed
    /// @param[in] changedBy Number of records that were added or removed
    void changeTLVRecordCount(int changedBy)
    {
      if (m_RecordCount != static_cast<size_t>(-1))
        m_RecordCount += changedBy;
    }
  };

  /// @class TLVRecordBuilder
  /// A base class for building Type-Length-Value (TLV) records. This builder receives the record parameters in its
  /// c'tor, builds the record raw buffer and provides a method to build a TLVRecord object out of it. Please notice
  /// this is a base class that lacks the capability of actually building TLVRecord objects and also cannot be
  /// instantiated. The reason for that is that different protocols build TLV records in different ways, so these
  /// missing capabilities will be implemented by the derived classes which are specific to each protocol. This class
  /// only provides the common infrastructure that will be used by them
  class TLVRecordBuilder
  {
  protected:
    TLVRecordBuilder();

    TLVRecordBuilder(uint32_t recType, const uint8_t* recValue, uint8_t recValueLen);

    TLVRecordBuilder(uint32_t recType, uint8_t recValue);

    TLVRecordBuilder(uint32_t recType, uint16_t recValue);

    TLVRecordBuilder(uint32_t recType, uint32_t recValue);

    TLVRecordBuilder(uint32_t recType, const IPv4Address& recValue);

    TLVRecordBuilder(uint32_t recType, const std::string& recValue, bool valueIsHexString = false);

    TLVRecordBuilder(const TLVRecordBuilder& other);

    TLVRecordBuilder& operator=(const TLVRecordBuilder& other);

    virtual ~TLVRecordBuilder();

    void init(uint32_t recType, const uint8_t* recValue, size_t recValueLen);

    uint8_t* m_RecValue;
    size_t m_RecValueLen;
    uint32_t m_RecType;

  private:
    void copyData(const TLVRecordBuilder& other);
  };
}  // namespace pcpp

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Created: 2025-09-27 08:03