TCP_Header.h

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#pragma once
/************************************************************************************
* Copyright (C) 2020                                                               *
* TETCOS, Bangalore. India                                                         *
*                                                                                  *
* Tetcos owns the intellectual property rights in the Product and its content.     *
* The copying, redistribution, reselling or publication of any or all of the       *
* Product or its content without express prior written consent of Tetcos is        *
* prohibited. Ownership and / or any other right relating to the software and all  *
* intellectual property rights therein shall remain at all times with Tetcos.      *
*                                                                                  *
* Author:    Shashi Kant Suman                                                     *
*                                                                                  *
* ---------------------------------------------------------------------------------*/
 
#ifndef _NETSIM_TCP_HEADER_H_
#define _NETSIM_TCP_HEADER_H_
#ifdef  __cplusplus
extern "C" {
#endif
 
    //If TCP.h file is not included in .c file.
#ifndef _NETSIM_TCP_H_
#define PNETSIM_SOCKET void*
#endif
 
    typedef enum enum_tcp_packet
    {
        TCPPACKET_SYN = TX_PROTOCOL_TCP * 100 + 1,
        TCPPACKET_SYNACK,
        TCPPACKET_FIN,
        TCPPACKET_RST,
        TCPPACKET_ACK,
    }TCPPACKET;
 
    typedef enum enum_tcp_option
    {
        TCP_OPTION_END,
        TCP_OPTION_NOOPERATION,
        TCP_OPTION_MSS,
        TCP_OPTION_WINDOW_SCALE,
        TCP_OPTION_SACK_PERMITTED,
        TCP_OPTION_SACK,
        TCP_OPTION_ECHO,        //obsoleted by option 8
        TCP_OPTION_ECHOREPLY,   //obsoleted by option 8
        TCP_OPTION_TIMESTAMP,
    }TCP_OPTION;
 
    typedef struct stru_tcp_option
    {
        TCP_OPTION type;
        void* option;
        UINT32 size;
        struct stru_tcp_option* next;
    }TCPOPTION,*PTCPOPTION;
 
/*
    TCP Header Format
 
 
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Source Port          |       Destination Port        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Sequence Number                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Acknowledgment Number                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Data |           |U|A|P|R|S|F|                               |
   | Offset| Reserved  |R|C|S|S|Y|I|            Window             |
   |       |           |G|K|H|T|N|N|                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Checksum            |         Urgent Pointer        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Options                    |    Padding    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             data                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
                            TCP Header Format
 */
    //Looks little different than RFC as below is used in Linux or windows.
    typedef struct stru_tcp_header
    {
        UINT16 SrcPort;
        UINT16 DstPort;
        UINT32 SeqNum;
        UINT32 AckNum;
        UINT32 HdrLength : 8;
        UINT32 Fin : 1;
        UINT32 Syn : 1;
        UINT32 Rst : 1;
        UINT32 Psh : 1;
        UINT32 Ack : 1;
        UINT32 Urg : 1;
        UINT32 Reserved : 2;
        UINT16 Window;
        UINT16 Checksum;
        UINT16 UrgPtr;
        PTCPOPTION option;
    }TCP_SEGMENT_HDR,*PTCP_SEGMENT_HDR;
#define TCP_HDR_SIZE        20 //Bytes
#define MAX_TCP_OPT_LEN     40 //Bytes
#define MAX_TCP_HDR_SIZE    (TCP_HDR_SIZE+MAX_TCP_OPT_LEN)
 
    static PTCP_SEGMENT_HDR TCP_GET_SEGMENT_HDR(NetSim_PACKET* packet)
    {
        if (packet && 
            packet->pstruTransportData &&
            packet->pstruTransportData->nTransportProtocol == TX_PROTOCOL_TCP)
            return packet->pstruTransportData->Packet_TransportProtocol;
        return NULL;
    }
 
    typedef struct stru_mss_option
    {
        UINT8 type;
        UINT8 len;
        UINT16 MSSData;
    }MSS_OPTION, *PMSS_OPTION;
#define MSS_OPTION_LEN  4 //Bytes
 
    typedef struct stru_sack_permitted_option
    {
        UINT8 type;
        UINT8 len;
    }SACKPERMITTED_OPTION, *PSACKPERMITTED_OPTION;
#define SACKPERMITTED_OPTION_LEN 2 //Bytes
 
    typedef struct stru_sack_data
    {
        UINT32 leftEdge;
        UINT32 rightEdge;
    }SACKDATA, *PSACKDATA;
#define SACKDATA_LEN    8 //Bytes
 
    typedef struct stru_sack_option
    {
        UINT8 type;
        UINT8 len;
        PSACKDATA* sackData;
    }SACK_OPTION, *PSACK_OPTION;
#define SACK_OPTION_FIX_LEN     2 //Bytes
#define SACK_OPTION_LEN(n) ((UINT8)(SACK_OPTION_FIX_LEN+(n)*SACKDATA_LEN)) //Bytes 
#define get_sack_data_count(sack) ((sack->len-SACK_OPTION_FIX_LEN)/SACKDATA_LEN)
 
    typedef struct stru_tcp_extra_option
    {
        UINT8 type;
    }EXTRA_OPTION, *PEXTRA_OPTION;
#define EXTRA_OPTION_LEN    1 //Bytes
 
    typedef struct stru_tcp_window_scale_option
    {
        UINT8 type;
        UINT8 len;
        UINT8 Shift_cnt;
    }Wsopt, *PWsopt;
#define WSOPT_LEN       3 //Bytes
 
    typedef struct stru_tcp_timestamp_option
    {
        UINT8 type;
        UINT8 len;
        UINT32 TSval;
        UINT32 TSecr;
    }TSopt, *PTSopt;
#define TSOPT_LEN       10 //Bytes
 
    //Function prototype
    PTCP_SEGMENT_HDR copy_tcp_hdr(PTCP_SEGMENT_HDR hdr);
    void free_tcp_hdr(PTCP_SEGMENT_HDR hdr);
    void* get_tcp_option(PTCP_SEGMENT_HDR hdr, TCP_OPTION type);
    void set_tcp_option(PTCP_SEGMENT_HDR hdr, void* option, TCP_OPTION type, UINT32 size);
 
    //SACK
    void set_sack_option(PNETSIM_SOCKET s, PTCP_SEGMENT_HDR hdr, double time);
    void receive_sack_option(PNETSIM_SOCKET s, PTCP_SEGMENT_HDR hdr);
 
    //Window Scaling
    void set_window_scaling(PNETSIM_SOCKET s, PWsopt opt);
 
    //TimeStamp option
    void set_timestamp_value(PNETSIM_SOCKET s,
                             PTCP_SEGMENT_HDR hdr,
                             PTSopt opt);
 
#ifdef  __cplusplus
}
#endif
#endif //_NETSIM_TCP_HEADER_H_