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

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#pragma once

#include "RawPacket.h"
#include "Layer.h"
#include <vector>

/// @file

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

  /**
   * @class Packet
   * This class represents a parsed packet. It contains the raw data (RawPacket instance), and a linked list of layers, each layer is a parsed
   * protocol that this packet contains. The layers linked list is ordered where the first layer is the lowest in the packet (currently it's always
   * Ethernet protocol as PcapPlusPlus supports only Ethernet packets), the next layer will be L2.5 or L3 (e.g VLAN, IPv4, IPv6, etc.), and so on.
   * etc.), etc. The last layer in the linked list will be the highest in the packet.
   * For example: for a standard HTTP request packet the layer will look like this: EthLayer -> IPv4Layer -> TcpLayer -> HttpRequestLayer <BR>
   * Packet instance isn't read only. The user can add or remove layers, update current layer, etc.
   */
  class Packet
  {
    friend class Layer;
  private:
    RawPacket* m_RawPacket;
    Layer* m_FirstLayer;
    Layer* m_LastLayer;
    size_t m_MaxPacketLen;
    bool m_FreeRawPacket;
    bool m_CanReallocateData;

  public:

    /**
     * A constructor for creating a new packet (with no layers).
     * When using this constructor an empty raw buffer is allocated (with the size of maxPacketLen) and a new RawPacket is created
     * @param[in] maxPacketLen The expected packet length in bytes
     */
    explicit Packet(size_t maxPacketLen = 1);

    /**
     * A constructor for creating a new packet with a buffer that is pre-allocated by the user.
     * The packet is created empty (with no layers), which means the constructor doesn't parse the data in the buffer.
     * Instead, all of the raw data of this packet it written to this buffer: whenever a layer is added, it's data is written to this buffer.
     * The buffer isn't freed and it's content isn't erased when the packet object is deleted.
     * This constructor is useful when you already have a memory buffer and you want to create packet data in it.
     * @param[in] buffer A pointer to a pre-allocated memory buffer
     * @param[in] bufferSize The size of the buffer
     */
    Packet(uint8_t* buffer, size_t bufferSize);

    /**
     * A constructor for creating a packet out of already allocated RawPacket. Very useful when parsing packets that came from the network.
     * When using this constructor a pointer to the RawPacket is saved (data isn't copied) and the RawPacket is parsed, meaning all layers
     * are created and linked to each other in the right order. In this overload of the constructor the user can specify whether to free
     * the instance of raw packet when the Packet is free or not
     * @param[in] rawPacket A pointer to the raw packet
     * @param[in] freeRawPacket Optional parameter. A flag indicating if the destructor should also call the raw packet destructor or not. Default value is false
     * @param[in] parseUntil Optional parameter. Parse the packet until you reach a certain protocol (inclusive). Can be useful for cases when you need to parse only up to a
     * certain layer and want to avoid the performance impact and memory consumption of parsing the whole packet. Default value is ::UnknownProtocol which means don't take this
     * parameter into account
     * @param[in] parseUntilLayer Optional parameter. Parse the packet until you reach a certain layer in the OSI model (inclusive). Can be useful for cases when you need to
     * parse only up to a certain OSI layer (for example transport layer) and want to avoid the performance impact and memory consumption of parsing the whole packet.
     * Default value is ::OsiModelLayerUnknown which means don't take this parameter into account
     */
    explicit Packet(RawPacket* rawPacket, bool freeRawPacket = false, ProtocolType parseUntil = UnknownProtocol, OsiModelLayer parseUntilLayer = OsiModelLayerUnknown);

    /**
     * A constructor for creating a packet out of already allocated RawPacket. Very useful when parsing packets that came from the network.
     * When using this constructor a pointer to the RawPacket is saved (data isn't copied) and the RawPacket is parsed, meaning all layers
     * are created and linked to each other in the right order. In this overload of the constructor the user can specify whether to free
     * the instance of raw packet when the Packet is free or not. This constructor should be used to parse the packet up to a certain layer
     * @param[in] rawPacket A pointer to the raw packet
     * @param[in] parseUntil Parse the packet until you reach a certain protocol (inclusive). Can be useful for cases when you need to parse only up to a
     * certain layer and want to avoid the performance impact and memory consumption of parsing the whole packet
     */
    explicit Packet(RawPacket* rawPacket, ProtocolType parseUntil);

    /**
     * A constructor for creating a packet out of already allocated RawPacket. Very useful when parsing packets that came from the network.
     * When using this constructor a pointer to the RawPacket is saved (data isn't copied) and the RawPacket is parsed, meaning all layers
     * are created and linked to each other in the right order. In this overload of the constructor the user can specify whether to free
     * the instance of raw packet when the Packet is free or not. This constructor should be used to parse the packet up to a certain layer
     * @param[in] rawPacket A pointer to the raw packet
     * @param[in] parseUntilFamily Parse the packet until you reach a certain protocol family (inclusive). Can be useful for cases when you need to parse only up to a
     * certain layer and want to avoid the performance impact and memory consumption of parsing the whole packet
     */
    explicit Packet(RawPacket* rawPacket, ProtocolTypeFamily parseUntilFamily);

    /**
     * A constructor for creating a packet out of already allocated RawPacket. Very useful when parsing packets that came from the network.
     * When using this constructor a pointer to the RawPacket is saved (data isn't copied) and the RawPacket is parsed, meaning all layers
     * are created and linked to each other in the right order. In this overload of the constructor the user can specify whether to free
     * the instance of raw packet when the Packet is free or not. . This constructor should be used to parse the packet up to a certain layer in the OSI model
     * @param[in] rawPacket A pointer to the raw packet
     * @param[in] parseUntilLayer Optional parameter. Parse the packet until you reach a certain layer in the OSI model (inclusive). Can be useful for cases when you need to
     * parse only up to a certain OSI layer (for example transport layer) and want to avoid the performance impact and memory consumption of parsing the whole packet
     */
    explicit Packet(RawPacket* rawPacket, OsiModelLayer parseUntilLayer);

    /**
     * A destructor for this class. Frees all layers allocated by this instance (Notice: it doesn't free layers that weren't allocated by this
     * class, for example layers that were added by addLayer() or insertLayer() ). In addition it frees the raw packet if it was allocated by
     * this instance (meaning if it was allocated by this instance constructor)
     */
    virtual ~Packet() { destructPacketData(); }

    /**
     * A copy constructor for this class. This copy constructor copies all the raw data and re-create all layers. So when the original Packet
     * is being freed, no data will be lost in the copied instance
     * @param[in] other The instance to copy from
     */
    Packet(const Packet& other) { copyDataFrom(other); }

    /**
     * Assignment operator overloading. It first frees all layers allocated by this instance (Notice: it doesn't free layers that weren't allocated by this
     * class, for example layers that were added by addLayer() or insertLayer() ). In addition it frees the raw packet if it was allocated by
     * this instance (meaning if it was allocated by this instance constructor).
     * Afterwards it copies the data from the other packet in the same way used in the copy constructor.
     * @param[in] other The instance to copy from
     */
    Packet& operator=(const Packet& other);

    /**
     * Get a pointer to the Packet's RawPacket
     * @return A pointer to the Packet's RawPacket
     */
    RawPacket* getRawPacket() const { return m_RawPacket; }

    /**
     * Set a RawPacket and re-construct all packet layers
     * @param[in] rawPacket Raw packet to set
     * @param[in] freeRawPacket A flag indicating if the destructor should also call the raw packet destructor or not
     * @param[in] parseUntil Parse the packet until it reaches this protocol. Can be useful for cases when you need to parse only up to a certain layer and want to avoid the
     * performance impact and memory consumption of parsing the whole packet. Default value is ::UnknownProtocol which means don't take this parameter into account
     * @param[in] parseUntilLayer Parse the packet until certain layer in OSI model. Can be useful for cases when you need to parse only up to a certain layer and want to avoid the
     * performance impact and memory consumption of parsing the whole packet. Default value is ::OsiModelLayerUnknown which means don't take this parameter into account
     */
    void setRawPacket(RawPacket* rawPacket, bool freeRawPacket, ProtocolTypeFamily parseUntil = UnknownProtocol, OsiModelLayer parseUntilLayer = OsiModelLayerUnknown);

    /**
     * Get a pointer to the Packet's RawPacket in a read-only manner
     * @return A pointer to the Packet's RawPacket
     */
    RawPacket* getRawPacketReadOnly() const { return m_RawPacket; }

    /**
     * Get a pointer to the first (lowest) layer in the packet
     * @return A pointer to the first (lowest) layer in the packet
     */
    Layer* getFirstLayer() const { return m_FirstLayer; }

    /**
     * Get a pointer to the last (highest) layer in the packet
     * @return A pointer to the last (highest) layer in the packet
     */
    Layer* getLastLayer() const { return m_LastLayer; }

    /**
     * Add a new layer as the last layer in the packet. This method gets a pointer to the new layer as a parameter
     * and attaches it to the packet. Notice after calling this method the input layer is attached to the packet so
     * every change you make in it affect the packet; Also it cannot be attached to other packets
     * @param[in] newLayer A pointer to the new layer to be added to the packet
     * @param[in] ownInPacket If true, Packet fully owns newLayer, including memory deletion upon destruct.  Default is false.
     * @return True if everything went well or false otherwise (an appropriate error log message will be printed in
     * such cases)
     */
    bool addLayer(Layer* newLayer, bool ownInPacket = false) { return insertLayer(m_LastLayer, newLayer, ownInPacket); }

    /**
     * Insert a new layer after an existing layer in the packet. This method gets a pointer to the new layer as a
     * parameter and attaches it to the packet. Notice after calling this method the input layer is attached to the
     * packet so every change you make in it affect the packet; Also it cannot be attached to other packets
     * @param[in] prevLayer A pointer to an existing layer in the packet which the new layer should followed by. If
     * this layer isn't attached to a packet and error will be printed to log and false will be returned
     * @param[in] newLayer A pointer to the new layer to be added to the packet
     * @param[in] ownInPacket If true, Packet fully owns newLayer, including memory deletion upon destruct.  Default is false.
     * @return True if everything went well or false otherwise (an appropriate error log message will be printed in
     * such cases)
     */
    bool insertLayer(Layer* prevLayer, Layer* newLayer, bool ownInPacket = false);


    /**
     * Remove an existing layer from the packet. The layer to removed is identified by its type (protocol). If the
     * packet has multiple layers of the same type in the packet the user may specify the index of the layer to remove
     * (the default index is 0 - remove the first layer of this type). If the layer was allocated during packet creation
     * it will be deleted and any pointer to it will get invalid. However if the layer was allocated by the user and
     * manually added to the packet it will simply get detached from the packet, meaning the pointer to it will stay
     * valid and its data (that was removed from the packet) will be copied back to the layer. In that case it's
     * the user's responsibility to delete the layer instance
     * @param[in] layerType The layer type (protocol) to remove
     * @param[in] index If there are multiple layers of the same type, indicate which instance to remove. The default
     * value is 0, meaning remove the first layer of this type
     * @return True if everything went well or false otherwise (an appropriate error log message will be printed in
     * such cases)
     */
    bool removeLayer(ProtocolType layerType, int index = 0);

    /**
     * Remove the first layer in the packet. The layer will be deleted if it was allocated during packet creation, or detached
     * if was allocated outside of the packet. Please refer to removeLayer() to get more info
     * @return True if layer removed successfully, or false if removing the layer failed or if there are no layers in the
     * packet. In any case of failure an appropriate error log message will be printed
     */
    bool removeFirstLayer();

    /**
     * Remove the last layer in the packet. The layer will be deleted if it was allocated during packet creation, or detached
     * if was allocated outside of the packet. Please refer to removeLayer() to get more info
     * @return True if layer removed successfully, or false if removing the layer failed or if there are no layers in the
     * packet. In any case of failure an appropriate error log message will be printed
     */
    bool removeLastLayer();

    /**
     * Remove all layers that come after a certain layer. All layers removed will be deleted if they were allocated during
     * packet creation or detached if were allocated outside of the packet, please refer to removeLayer() to get more info
     * @param[in] layer A pointer to the layer to begin removing from. Please note this layer will not be removed, only the
     * layers that come after it will be removed. Also, if removal of one layer failed, the method will return immediately and
     * the following layers won't be deleted
     * @return True if all layers were removed successfully, or false if failed to remove at least one layer. In any case of
     * failure an appropriate error log message will be printed
     */
    bool removeAllLayersAfter(Layer* layer);

    /**
     * Detach a layer from the packet. Detaching means the layer instance will not be deleted, but rather separated from the
     * packet - e.g it will be removed from the layer chain of the packet and its data will be copied from the packet buffer
     * into an internal layer buffer. After a layer is detached, it can be added into another packet (but it's impossible to
     * attach a layer to multiple packets in the same time). After layer is detached, it's the user's responsibility to
     * delete it when it's not needed anymore
     * @param[in] layerType The layer type (protocol) to detach from the packet
     * @param[in] index If there are multiple layers of the same type, indicate which instance to detach. The default
     * value is 0, meaning detach the first layer of this type
     * @return A pointer to the detached layer or NULL if detaching process failed. In any case of failure an
     * appropriate error log message will be printed
     */
    Layer* detachLayer(ProtocolType layerType, int index = 0);

    /**
     * Detach a layer from the packet. Detaching means the layer instance will not be deleted, but rather separated from the
     * packet - e.g it will be removed from the layer chain of the packet and its data will be copied from the packet buffer
     * into an internal layer buffer. After a layer is detached, it can be added into another packet (but it's impossible to
     * attach a layer to multiple packets at the same time). After layer is detached, it's the user's responsibility to
     * delete it when it's not needed anymore
     * @param[in] layer A pointer to the layer to detach
     * @return True if the layer was detached successfully, or false if something went wrong. In any case of failure an
     * appropriate error log message will be printed
     */
    bool detachLayer(Layer* layer) { return removeLayer(layer, false); }

    /**
     * Get a pointer to the layer of a certain type (protocol). This method goes through the layers and returns a layer
     * that matches the give protocol type
     * @param[in] layerType The layer type (protocol) to fetch
     * @param[in] index If there are multiple layers of the same type, indicate which instance to fetch. The default
     * value is 0, meaning fetch the first layer of this type
     * @return A pointer to the layer or NULL if no such layer was found
     */
    Layer* getLayerOfType(ProtocolType layerType, int index = 0) const;

    /**
     * A templated method to get a layer of a certain type (protocol). If no layer of such type is found, NULL is returned
     * @param[in] reverseOrder The optional parameter that indicates that the lookup should run in reverse order, the default value is false
     * @return A pointer to the layer of the requested type, NULL if not found
     */
    template<class TLayer>
    TLayer* getLayerOfType(bool reverseOrder = false) const;

    /**
     * A templated method to get the first layer of a certain type (protocol), start searching from a certain layer.
     * For example: if a packet looks like: EthLayer -> VlanLayer(1) -> VlanLayer(2) -> VlanLayer(3) -> IPv4Layer
     * and the user put VlanLayer(2) as a parameter and wishes to search for a VlanLayer, VlanLayer(3) will be returned
     * If no layer of such type is found, NULL is returned
     * @param[in] startLayer A pointer to the layer to start search from
     * @return A pointer to the layer of the requested type, NULL if not found
     */
    template<class TLayer>
    TLayer* getNextLayerOfType(Layer* startLayer) const;

    /**
     * A templated method to get the first layer of a certain type (protocol), start searching from a certain layer.
     * For example: if a packet looks like: EthLayer -> VlanLayer(1) -> VlanLayer(2) -> VlanLayer(3) -> IPv4Layer
     * and the user put VlanLayer(2) as a parameter and wishes to search for a VlanLayer, VlanLayer(1) will be returned
     * If no layer of such type is found, NULL is returned
     * @param[in] startLayer A pointer to the layer to start search from
     * @return A pointer to the layer of the requested type, NULL if not found
     */
    template<class TLayer>
    TLayer* getPrevLayerOfType(Layer* startLayer) const;

    /**
     * Check whether the packet contains a layer of a certain protocol
     * @param[in] protocolType The protocol type to search
     * @return True if the packet contains a layer of a certain protocol, false otherwise
     */
    bool isPacketOfType(ProtocolType protocolType) const;

    /**
    * Check whether the packet contains a layer of a certain protocol family
    * @param[in] protocolTypeFamily The protocol type family to search
     * @return True if the packet contains a layer of a certain protocol family, false otherwise
     */
    bool isPacketOfType(ProtocolTypeFamily protocolTypeFamily) const;

    /**
     * Each layer can have fields that can be calculate automatically from other fields using Layer#computeCalculateFields(). This method forces all layers to calculate these
     * fields values
     */
    void computeCalculateFields();

    /**
     * Each layer can print a string representation of the layer most important data using Layer#toString(). This method aggregates this string from all layers and
     * print it to a complete string containing all packet's relevant data
     * @param[in] timeAsLocalTime Print time as local time or GMT. Default (true value) is local time, for GMT set to false
     * @return A string containing most relevant data from all layers (looks like the packet description in Wireshark)
     */
    std::string toString(bool timeAsLocalTime = true) const;

    /**
     * Similar to toString(), but instead of one string it outputs a list of strings, one string for every layer
     * @param[out] result A string vector that will contain all strings
     * @param[in] timeAsLocalTime Print time as local time or GMT. Default (true value) is local time, for GMT set to false
     */
    void toStringList(std::vector<std::string>& result, bool timeAsLocalTime = true) const;

  private:
    void copyDataFrom(const Packet& other);

    void destructPacketData();

    bool extendLayer(Layer* layer, int offsetInLayer, size_t numOfBytesToExtend);
    bool shortenLayer(Layer* layer, int offsetInLayer, size_t numOfBytesToShorten);

    void reallocateRawData(size_t newSize);

    bool removeLayer(Layer* layer, bool tryToDelete);

    std::string printPacketInfo(bool timeAsLocalTime) const;

    Layer* createFirstLayer(LinkLayerType linkType);
  }; // class Packet


  // implementation of inline methods

  template<class TLayer>
  TLayer* Packet::getLayerOfType(bool reverse) const
  {
    if (!reverse)
    {
      if (dynamic_cast<TLayer*>(getFirstLayer()) != NULL)
        return dynamic_cast<TLayer*>(getFirstLayer());

      return getNextLayerOfType<TLayer>(getFirstLayer());
    }

    // lookup in reverse order
    if (dynamic_cast<TLayer*>(getLastLayer()) != NULL)
      return dynamic_cast<TLayer*>(getLastLayer());

    return getPrevLayerOfType<TLayer>(getLastLayer());
  }

  template<class TLayer>
  TLayer* Packet::getNextLayerOfType(Layer* curLayer) const
  {
    if (curLayer == NULL)
      return NULL;

    curLayer = curLayer->getNextLayer();
    while ((curLayer != NULL) && (dynamic_cast<TLayer*>(curLayer) == NULL))
    {
      curLayer = curLayer->getNextLayer();
    }

    return dynamic_cast<TLayer*>(curLayer);
  }

  template<class TLayer>
  TLayer* Packet::getPrevLayerOfType(Layer* curLayer) const
  {
    if (curLayer == NULL)
      return NULL;

    curLayer = curLayer->getPrevLayer();
    while (curLayer != NULL && dynamic_cast<TLayer*>(curLayer) == NULL)
    {
      curLayer = curLayer->getPrevLayer();
    }

    return dynamic_cast<TLayer*>(curLayer);
  }

} // namespace pcpp

inline std::ostream& operator<<(std::ostream& os, const pcpp::Packet& packet)
{
  os << packet.toString();
  return os;
}

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Created: 2024-02-25 06:29