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#ifndef UMP_TCP_H
#define UMP_TCP_H

/* TCP packet manipulating functions */

#include "ump-common.h"

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

#define UMP_PKT_SIZE 1024

typedef struct UmpPktStruct {
    uint8_t data[UMP_PKT_SIZE];
    size_t app_data_len;
} UmpPkt;

/* Accessor function for UmpPkt, prefixed with ump_pkt */

UMP_COMMON_DEFINE_BOTH (UmpPkt, ump_pkt, src_port, 0, uint16_t);
UMP_COMMON_DEFINE_BOTH (UmpPkt, ump_pkt, dest_port, 2, uint16_t);
UMP_COMMON_DEFINE_BOTH (UmpPkt, ump_pkt, seq_num, 4, uint32_t);
UMP_COMMON_DEFINE_BOTH (UmpPkt, ump_pkt, ack_num, 8, uint32_t);

#define ump_pkt_get_hdr_len ump_pkt_get_data_offset
static inline uint8_t ump_pkt_get_data_offset (UmpPkt* pkt) {
    uint8_t* p = UMP_COMMON_MOVE_POINTER (pkt, 12);
    uint8_t hdr_len = *p;
    return (hdr_len >> 4) << 2;
}
#define ump_pkt_set_hdr_len ump_pkt_set_data_offset
static inline void ump_pkt_set_data_offset (UmpPkt* pkt, uint8_t x) {
    uint8_t* p = UMP_COMMON_MOVE_POINTER (pkt, 12);
    uint8_t hdr_len = (*p) | ((x >> 2) << 4);
    *p = hdr_len;
}

UMP_COMMON_DEFINE_BOTH_FLAG (UmpPkt, ump_pkt, flag_ns, 12, 1);
UMP_COMMON_DEFINE_BOTH_FLAG (UmpPkt, ump_pkt, flag_cwr, 13, 7);
UMP_COMMON_DEFINE_BOTH_FLAG (UmpPkt, ump_pkt, flag_ece, 13, 6);
UMP_COMMON_DEFINE_BOTH_FLAG (UmpPkt, ump_pkt, flag_urg, 13, 5);
UMP_COMMON_DEFINE_BOTH_FLAG (UmpPkt, ump_pkt, flag_ack, 13, 4);
UMP_COMMON_DEFINE_BOTH_FLAG (UmpPkt, ump_pkt, flag_psh, 13, 3);
UMP_COMMON_DEFINE_BOTH_FLAG (UmpPkt, ump_pkt, flag_rst, 13, 2);
UMP_COMMON_DEFINE_BOTH_FLAG (UmpPkt, ump_pkt, flag_syn, 13, 1);
UMP_COMMON_DEFINE_BOTH_FLAG (UmpPkt, ump_pkt, flag_fin, 13, 0);

UMP_COMMON_DEFINE_BOTH (UmpPkt, ump_pkt, window_size, 14, uint16_t);
UMP_COMMON_DEFINE_BOTH (UmpPkt, ump_pkt, checksum, 16, uint16_t);
UMP_COMMON_DEFINE_BOTH (UmpPkt, ump_pkt, urgent_ptr, 18, uint16_t);

static inline uint8_t* ump_pkt_get_app_data (UmpPkt* pkt) {
    uint8_t off = ump_pkt_get_data_offset (pkt);
    return UMP_COMMON_MOVE_POINTER (pkt, off);
}
static inline size_t ump_pkt_get_app_data_len (UmpPkt* pkt) {
    return pkt->app_data_len;
}
static inline size_t ump_pkt_get_app_data_max (UmpPkt* pkt) {
    return UMP_PKT_SIZE - ump_pkt_get_data_offset (pkt);
}
static inline void ump_pkt_set_app_data (
    UmpPkt* pkt, const uint8_t* data, size_t len) {

    uint8_t* app_data = ump_pkt_get_app_data (pkt);
    ump_common_copy (app_data, data, len);
    pkt->app_data_len = len;
}

static inline void ump_pkt_init (UmpPkt* pkt) {
    memset (pkt, 0, sizeof (UmpPkt));
    ump_pkt_set_data_offset (pkt, 20);
}

/* Other convenient functions */

uint16_t ump_pkt_calc_checksum (UmpPkt* pkt, bool skip_checksum);
void ump_pkt_fill_checksum (UmpPkt* pkt);
bool ump_pkt_verify_checksum (UmpPkt* pkt);

#endif /* UMP_TCP_H */