/***************************************************************************
 * IPv4Header.h -- The IPv4Header Class represents an IPv4 datagram. It    *
 * contains methods to set any header field. In general, these methods do  *
 * error checkings and byte order conversion.                              *
 *                                                                         *
 ***********************IMPORTANT NMAP LICENSE TERMS************************
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 ***************************************************************************/
/* This code was originally part of the Nping tool.                        */

#ifndef IPV4HEADER_H
#define IPV4HEADER_H 1

#include "NetworkLayerElement.h"

#define IP_RF 0x8000               /* Reserved fragment flag         */
#define IP_DF 0x4000               /* Don't fragment flag            */
#define IP_MF 0x2000               /* More fragments flag            */
#define IP_OFFMASK 0x1fff          /* Mask for fragmenting bits      */
#define IP_HEADER_LEN 20           /* Length of the standard header  */
#define MAX_IP_OPTIONS_LEN 40      /* Max Length for IP Options      */

/* Default header values */
#define IPv4_DEFAULT_TOS      0
#define IPv4_DEFAULT_ID       0
#define IPv4_DEFAULT_TTL      64
#define IPv4_DEFAULT_PROTO    6 /* TCP */

class IPv4Header : public NetworkLayerElement {

    private:
        /*
         0                   1                   2                   3
         0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |Version|  IHL  |Type of Service|          Total Length         |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |         Identification        |Flags|      Fragment Offset    |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |  Time to Live |    Protocol   |         Header Checksum       |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                       Source Address                          |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                    Destination Address                        |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                    Options                    |    Padding    |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        */
        struct nping_ipv4_hdr {
        #if WORDS_BIGENDIAN
            u8 ip_v:4;                     /* Version                        */
            u8 ip_hl:4;                    /* Header length                  */
        #else
            u8 ip_hl:4;                    /* Header length                  */
            u8 ip_v:4;                     /* Version                        */
        #endif
            u8 ip_tos;                     /* Type of service                */
            u16 ip_len;                    /* Total length                   */
            u16 ip_id;                     /* Identification                 */
            u16 ip_off;                    /* Fragment offset field          */
            u8 ip_ttl;                     /* Time to live                   */
            u8 ip_p;                       /* Protocol                       */
            u16 ip_sum;                    /* Checksum                       */
            struct in_addr ip_src;         /* Source IP address              */
            struct in_addr ip_dst;         /* Destination IP address         */
            u8 options[MAX_IP_OPTIONS_LEN];  /* IP Options                   */
        }__attribute__((__packed__));

        typedef struct nping_ipv4_hdr nping_ipv4_hdr_t;

        nping_ipv4_hdr_t h;

        int ipoptlen; /**< Length of IP options */

    public:

        /* Misc */
        IPv4Header();
        ~IPv4Header();
        void reset();
        u8 *getBufferPointer();
        int storeRecvData(const u8 *buf, size_t len);
        int protocol_id() const;
        int validate();
        int print(FILE *output, int detail) const;

        /* IP version */
        int setVersion();
        u8 getVersion() const;

        /* Header Length */
        int setHeaderLength();
        int setHeaderLength(u8 l);
        u8 getHeaderLength() const;

        /* Type of Service */
        int setTOS(u8 v);
        u8 getTOS() const;

        /* Total length of the datagram */
        int setTotalLength();
        int setTotalLength(u16 l);
        u16 getTotalLength() const;

        /* Identification value */
        int setIdentification();
        int setIdentification(u16 i);
        u16 getIdentification() const;

        /* Fragment Offset */
        int setFragOffset();
        int setFragOffset(u16 f);
        u16 getFragOffset() const;

        /* Flags */
        int setRF();
        int unsetRF();
        bool getRF() const;
        int setDF();
        int unsetDF();
        bool getDF() const;
        int setMF();
        int unsetMF();
        bool getMF() const;

        /* Time to live */
        int setTTL();
        int setTTL(u8 t);
        u8 getTTL() const;

        /* Next protocol */
        int setNextProto(u8 p);
        int setNextProto(const char *p);
        u8 getNextProto() const;
        int setNextHeader(u8 val);
        u8 getNextHeader() const;

        /* Checksum */
        int setSum();
        int setSum(u16 s);
        int setSumRandom();
        u16 getSum() const;

        /* Destination IP */
        int setDestinationAddress(u32 d);
        int setDestinationAddress(struct in_addr d);
        const u8 *getDestinationAddress() const;
        struct in_addr getDestinationAddress(struct in_addr *result) const;


        /* Source IP */
        int setSourceAddress(u32 d);
        int setSourceAddress(struct in_addr d);
        const u8 *getSourceAddress() const;
        struct in_addr getSourceAddress(struct in_addr *result) const;

        u16 getAddressLength() const;

        /* IP Options */
        int setOpts(const char *txt);
        int setOpts(u8 *opts_buff,  u32 opts_len);
        const u8 *getOpts() const;
        const u8 *getOpts(int *len) const;
        int printOptions() const;
        const char *getOptionsString() const;

}; /* End of class IPv4Header */

#endif
