net/ipv4.h


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// http://www.saminiir.com/lets-code-tcp-ip-stack-2-ipv4-icmpv4/
#include <stdint.h>
#include <stdbool.h>

#include "eth.h"
#include "netdev.h"

struct ipv4_hdr {
    uint8_t ihl : 4;		 // 4bit / number of 32 bit words in header
    uint8_t version : 4;	 // 4bit /  4 - ipv4
    uint8_t tos;		 // type of service
    uint16_t len;		 // total length of ip datagramm
    uint16_t id;		 // index of datagram for fragmentation
    uint16_t flags : 3;		 // various control flags
    uint16_t frag_offset : 13;	 // fragment offset 0 - first
    uint8_t ttl;		 // time to live - countdown decreased by each receiver
    uint8_t proto;		 // payload protocol / 1-icmp, 16 - udp , 6 -tcp
    uint16_t csum;		 // header checksum
    uint32_t saddr;		 // source ip address
    uint32_t daddr;		 // destination ip address
} __attribute__((packed));

uint16_t ipv4_checksum(void *addr, int count);
bool ipv4_incoming(struct netdev *,struct eth_hdr *);
uint16_t ipv4_checksum(void *addr, int count);