#pragma once

/// @file

#include "Layer.h"

/// @namespace pcpp

/// @brief The main namespace for the PcapPlusPlus lib

namespace pcpp

{

  /// @struct ipsec_authentication_header

  /// Represents IPSec AuthenticationHeader (AH) structure

#pragma pack(push, 1)

  struct ipsec_authentication_header

  {

    /// Type of the next header

    uint8_t nextHeader;

    /// The length of the Authentication Header in 4-octet units, minus 2

    uint8_t payloadLen;

    /// Reserved

    uint16_t reserved;

    /// Security Parameters Index

    uint32_t spi;

    /// Sequence Number

    uint32_t sequenceNumber;

  };

#pragma pack(pop)

  static_assert(sizeof(ipsec_authentication_header) == 12, "ipsec_authentication_header size is not 12 bytes");

  /// @struct ipsec_esp

  /// Represents IPSec Encapsulating Security Payload (ESP) structure

#pragma pack(push, 1)

  struct ipsec_esp

  {

    /// Security Parameters Index

    uint32_t spi;

    /// Sequence Number

    uint32_t sequenceNumber;

  };

#pragma pack(pop)

  static_assert(sizeof(ipsec_esp) == 8, "ipsec_esp size is not 8 bytes");

  /// @class AuthenticationHeaderLayer

  /// Represents an IPSec AuthenticationHeader (AH) layer

  class AuthenticationHeaderLayer : public Layer

  {

  public:

    /// A constructor that creates the layer from an existing packet raw data

    /// @param[in] data A pointer to the raw data

    /// @param[in] dataLen Size of the data in bytes

    /// @param[in] prevLayer A pointer to the previous layer

    /// @param[in] packet A pointer to the Packet instance where layer will be stored in

    AuthenticationHeaderLayer(uint8_t* data, size_t dataLen, Layer* prevLayer, Packet* packet)

        : Layer(data, dataLen, prevLayer, packet, AuthenticationHeader)

    {}

    /// Get a pointer to the raw AH header. Notice this points directly to the data, so every change will change the

    /// actual packet data

    /// @return A pointer to the ipsec_authentication_header

    ipsec_authentication_header* getAHHeader() const

    {

      return reinterpret_cast<ipsec_authentication_header*>(m_Data);

    }

    /// @return The Security Parameters Index (SPI) field value

    uint32_t getSPI() const;

    /// @return The sequence number value

    uint32_t getSequenceNumber() const;

    /// @return The size of the Integrity Check Value (ICV)

    size_t getICVLength() const;

    /// @return A pointer to the raw data of the Integrity Check Value (ICV)

    uint8_t* getICVBytes() const;

    /// @return The value of the Integrity Check Value (ICV) as a hex string

    std::string getICVHexStream() const;

    /// A static method that validates the input data

    /// @param[in] data The pointer to the beginning of a byte stream of a AuthenticationHeader layer

    /// @param[in] dataLen The length of byte stream

    /// @return True if the data is valid and can represent an AuthenticationHeader layer

    static inline bool isDataValid(const uint8_t* data, size_t dataLen);

    // implement abstract methods

    /// @return The size of the AH header

    size_t getHeaderLen() const override

    {

      return static_cast<size_t>(4) * (getAHHeader()->payloadLen + 2);

    }

    /// Currently identifies the following next layers: UdpLayer, TcpLayer, IPv4Layer, IPv6Layer and ESPLayer.

    /// Otherwise sets PayloadLayer

    void parseNextLayer() override;

    /// Does nothing for this layer

    void computeCalculateFields() override

    {}

    std::string toString() const override;

    OsiModelLayer getOsiModelLayer() const override

    {

      return OsiModelNetworkLayer;

    }

  private:

    // this layer supports parsing only

    AuthenticationHeaderLayer()

    {}

  };

  /// @class ESPLayer

  /// Represents an IPSec Encapsulating Security Payload (ESP) layer

  class ESPLayer : public Layer

  {

  public:

    /// A constructor that creates the layer from an existing packet raw data

    /// @param[in] data A pointer to the raw data

    /// @param[in] dataLen Size of the data in bytes

    /// @param[in] prevLayer A pointer to the previous layer

    /// @param[in] packet A pointer to the Packet instance where layer will be stored in

    ESPLayer(uint8_t* data, size_t dataLen, Layer* prevLayer, Packet* packet)

        : Layer(data, dataLen, prevLayer, packet, ESP)

    {}

    ipsec_esp* getESPHeader() const

    {

      return reinterpret_cast<ipsec_esp*>(m_Data);

    }

    /// @return The Security Parameters Index (SPI) field value

    uint32_t getSPI() const;

    /// @return The sequence number value

    uint32_t getSequenceNumber() const;

    /// A static method that validates the input data

    /// @param[in] data The pointer to the beginning of a byte stream of a ESP layer

    /// @param[in] dataLen The length of byte stream

    /// @return True if the data is valid and can represent an ESP layer

    static inline bool isDataValid(const uint8_t* data, size_t dataLen);

    // implement abstract methods

    /// @return The size of the ESP header (8 bytes)

    size_t getHeaderLen() const override

    {

      return sizeof(ipsec_esp);

    }

    /// The payload of an ESP layer is encrypted, hence the next layer is always a generic payload (PayloadLayer)

    void parseNextLayer() override;

    /// Does nothing for this layer

    void computeCalculateFields() override

    {}

    std::string toString() const override;

    OsiModelLayer getOsiModelLayer() const override

    {

      return OsiModelTransportLayer;

    }

  private:

    // this layer supports parsing only

    ESPLayer()

    {}

  };

  // implementation of inline methods

  bool AuthenticationHeaderLayer::isDataValid(const uint8_t* data, size_t dataLen)

  {

    if (dataLen < sizeof(ipsec_authentication_header))

      return false;

    size_t payloadLen = 4 * (data[1] + 2);

    if (payloadLen < sizeof(ipsec_authentication_header) || payloadLen > dataLen)

      return false;

    return true;

  }

  bool ESPLayer::isDataValid(const uint8_t* data, size_t dataLen)

  {

    return data && dataLen >= sizeof(ipsec_esp);

  }

}  // namespace pcpp