hdr.h

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/*
 * SPDX-FileCopyrightText: 2015 José Ignacio Alamos <jialamos@uc.cl>
 * SPDX-License-Identifier: LGPL-2.1-only
 */
 
#pragma once

 
#include <assert.h>
 
#include "byteorder.h"
#include "net/ipv4/addr.h"
 
#ifdef __cplusplus
extern "C" {
#endif

#define IPV4_HDR_FLAGS_RESERVED     (0x04)      
#define IPV4_HDR_FLAGS_DF           (0x02)      
#define IPV4_HDR_FLAGS_MF           (0x01)      

typedef struct __attribute__((packed)) {
    uint8_t v_ihl;
    uint8_t ts;             
    network_uint16_t tl;    
    network_uint16_t id;    
    network_uint16_t fl_fo;
    uint8_t ttl;            
    uint8_t protocol;       
    network_uint16_t csum;  
    ipv4_addr_t src;        
    ipv4_addr_t dst;        
} ipv4_hdr_t;

static inline void ipv4_hdr_set_version(ipv4_hdr_t *hdr)
{
    hdr->v_ihl &= 0x0f;
    hdr->v_ihl |= 0x40;
}

static inline uint8_t ipv4_hdr_get_version(ipv4_hdr_t *hdr)
{
    return ((hdr->v_ihl) >> 4);
}

static inline void ipv4_hdr_set_ihl(ipv4_hdr_t *hdr, uint16_t ihl)
{
    assert(ihl >= 20 && ihl <= 60);
    assert(ihl % 4 == 0);
 
    hdr->v_ihl &= 0xf0;
    hdr->v_ihl |= 0x0f & (ihl >> 2);
}

static inline uint16_t ipv4_hdr_get_ihl(ipv4_hdr_t *hdr)
{
    return (hdr->v_ihl & 0x0f) << 2;
}

static inline void ipv4_hdr_set_flags(ipv4_hdr_t *hdr, uint8_t flags)
{
    hdr->fl_fo.u8[0] &= 0x1f;
    hdr->fl_fo.u8[0] |= (0xe0 & (flags << 5));
}

static inline uint8_t ipv4_hdr_get_flags(ipv4_hdr_t *hdr)
{
    return (((hdr->fl_fo.u8[0]) >> 5) & 0x07);
}

static inline void ipv4_hdr_set_fo(ipv4_hdr_t *hdr, uint16_t fo)
{
    hdr->fl_fo.u8[0] &= 0xe0;
    hdr->fl_fo.u8[0] |= (0x1f & (fo >> 8));
    hdr->fl_fo.u8[1] = 0xff & fo;
}

static inline uint16_t ipv4_hdr_get_fo(ipv4_hdr_t *hdr)
{
    return (((hdr->fl_fo.u8[0] & 0x1f) << 8) + hdr->fl_fo.u8[1]);
}
 
#ifdef __cplusplus
}
#endif