ip.h

#ifndef IP_H
#define IP_H

#include <stddef.h>
#include <stdint.h>
#include <unistd.h>
#include "net.h"

#define IP_VERSION_IPV4 4

#define IP_PROTOCOL_ICMP 1
#define IP_PROTOCOL_TCP 6
#define IP_PROTOCOL_UDP 17
#define IP_PROTOCOL_RAW 255

#define IP_HDR_SIZE_MIN 20
#define IP_HDR_SIZE_MAX 60

#define IP_PAYLOAD_SIZE_MAX (65535 - IP_HDR_SIZE_MIN)

#define IP_ADDR_LEN 4
#define IP_ADDR_STR_LEN 16 /* "ddd.ddd.ddd.ddd\0" */

typedef uint32_t ip_addr_t;

struct ip_hdr {
  uint8_t vhl;
  uint8_t tos;
  uint16_t len;
  uint16_t id;
  uint16_t offset;
  uint8_t ttl;
  uint8_t protocol;
  uint16_t sum;
  ip_addr_t src;
  ip_addr_t dst;
  uint8_t options[0];
};

struct netif_ip {
  struct netif netif;
  ip_addr_t unicast;
  ip_addr_t netmask;
  ip_addr_t network;
  ip_addr_t broadcast;
  ip_addr_t gateway;
};

extern const ip_addr_t IP_ADDR_ANY;
extern const ip_addr_t IPADDR_BROADCAST;

int ip_addr_pton(const char *p, ip_addr_t *n);
char *ip_addr_ntop(const ip_addr_t *n, char *p, size_t size);

struct netif *ip_netif_register(struct netdev *dev, const char *addr,
                                const char *netmask, const char *gateway);
struct netif *ip_netif_by_addr(ip_addr_t *addr);
struct netif *ip_netif_by_peer(ip_addr_t *peer);

ssize_t ip_tx(struct netif *netif, uint8_t protocol, const uint8_t *buf,
              size_t len, const ip_addr_t *dst);
int ip_add_protocol(uint8_t protocol,
                    void (*handler)(uint8_t *, size_t, ip_addr_t *, ip_addr_t *,
                                    struct netif *));
int ip_init(void);

#endif