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

Source
#pragma once

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

/// @file

/// @namespace pcpp
/// @brief The main namespace for the PcapPlusPlus lib
namespace pcpp
{
  /// @brief Options struct for configuring packet parsing behavior.
  ///
  /// The parsing options are combined. If multiple stop conditions are specified, parsing stops
  /// as soon as any condition is met.
  struct PacketParseOptions
  {
    /// @brief Defines the protocol type up to and including which the packet should be parsed (inclusive).
    ///
    /// For large packets where only the lower layers are of interest, this option can be used to limit the parsing
    /// procedure to the desired protocol. The packet is parsed until the specified protocol is reached and
    /// consumed. Layers beyond this protocol are not parsed, which can improve performance and reduce
    /// memory usage.
    ///
    /// @remarks If multiple consecutive layers of the same protocol type exist, parsing stops after exhausting the
    /// first contiguous sequence of that protocol type. This matters for protocols that may appear multiple times
    /// in succession within a packet (e.g. BgpLayer).
    ProtocolTypeFamily parseUntilProtocol = UnknownProtocol;

    /// @brief Defines an OSI model layer up to and including which the packet should be parsed (inclusive).
    ///
    /// For large packets where only the lower layers are of interest, this option can be used to limit the parsing
    /// procedure to the desired OSI layer. The packet is parsed until all layers belonging to the specified OSI
    /// layer are consumed. Layers beyond that are ignored, which can improve performance and reduce memory usage.
    OsiModelLayer parseUntilLayer = OsiModelLayerUnknown;
  };

  /// @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
    /// @param[in] linkType The link type to use for this packet (the default is Ethernet)
    explicit Packet(size_t maxPacketLen = 1, LinkLayerType linkType = LINKTYPE_ETHERNET);

    /// 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
    /// @param[in] linkType The link type to use for this packet (the default is Ethernet)
    Packet(uint8_t* buffer, size_t bufferSize, LinkLayerType linkType = LINKTYPE_ETHERNET);

    /// 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);

    /// @brief Parse the packet according to the provided options.
    ///
    /// The packet is parsed according to the specified options, constructing the layer hierarchy if it does not
    /// exist. If the packet has already been parsed, it will be re-parsed based on the new options.
    ///
    /// If @p incrementalParsing is true, the procedure will reuse existing layers where possible, only creating new
    /// layers for previously unparsed data. Otherwise, all existing layers are discarded and the packet is parsed
    /// from scratch.
    ///
    /// @param[in] options Parsing options to configure the parsing behavior.
    /// @param[in] incrementalParsing If 'true', incremental parsing is performed, reusing existing layers where
    /// possible.
    /// @throws std::runtime_error if there is no RawPacket associated with this Packet instance.
    void parsePacket(PacketParseOptions options, bool incrementalParsing = true);

    /// Get a pointer to the Packet's RawPacket in a read-only manner
    /// @return A pointer to the Packet's RawPacket
    const 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 nullptr 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 nullptr 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, nullptr
    /// 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, nullptr 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, nullptr is returned
    /// @param[in] startLayer A pointer to the layer to start search from
    /// @return A pointer to the layer of the requested type, nullptr 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, nullptr is returned
    /// @param[in] startLayer A pointer to the layer to start search from
    /// @return A pointer to the layer of the requested type, nullptr 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();
    void destroyAllLayers();

    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);

    template <typename TLayer, typename NextLayerFn>
    static TLayer* searchLayerStackForType(Layer* startLayer, NextLayerFn nextLayerFn, bool skipFirst);
  };  // class Packet

  // implementation of inline methods

  template <class TLayer> TLayer* Packet::getLayerOfType(bool reverse) const
  {
    if (!reverse)
    {
      return searchLayerStackForType<TLayer>(
          m_FirstLayer, [](Layer* layer) { return layer->getNextLayer(); }, false);
    }

    // lookup in reverse order
    return searchLayerStackForType<TLayer>(m_LastLayer, [](Layer* layer) { return layer->getPrevLayer(); }, false);
  }

  template <class TLayer> TLayer* Packet::getNextLayerOfType(Layer* curLayer) const
  {
    return searchLayerStackForType<TLayer>(curLayer, [](Layer* layer) { return layer->getNextLayer(); }, true);
  }

  template <class TLayer> TLayer* Packet::getPrevLayerOfType(Layer* curLayer) const
  {
    return searchLayerStackForType<TLayer>(curLayer, [](Layer* layer) { return layer->getPrevLayer(); }, true);
  }

  template <typename TLayer, typename NextLayerFn>
  TLayer* Packet::searchLayerStackForType(Layer* curLayer, NextLayerFn nextLayerFn, bool skipFirst)
  {
    if (curLayer == nullptr)
      return nullptr;

    if (skipFirst)
    {
      curLayer = nextLayerFn(curLayer);
    }

    while (curLayer != nullptr)
    {
      auto* curLayerCasted = dynamic_cast<TLayer*>(curLayer);
      if (curLayerCasted != nullptr)
        return curLayerCasted;

      curLayer = nextLayerFn(curLayer);
    }

    return nullptr;
  }

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

Coverage Report

Created: 2026-02-14 06:19