#pragma once

#ifdef __cplusplus
extern "C" {
#endif

#include <endian.h>
#include <netinet/in.h>
#include <stdint.h>

struct ip6_hdr {
    union {
        struct ip6_hdrctl {
            uint32_t ip6_un1_flow;
            uint16_t ip6_un1_plen;
            uint8_t ip6_un1_nxt;
            uint8_t ip6_un1_hlim;
        } ip6_un1;
        uint8_t ip6_un2_vfc;
    } ip6_ctlun;
    struct in6_addr ip6_src;
    struct in6_addr ip6_dst;
};

#define ip6_vfc ip6_ctlun.ip6_un2_vfc
#define ip6_flow ip6_ctlun.ip6_un1.ip6_un1_flow
#define ip6_plen ip6_ctlun.ip6_un1.ip6_un1_plen
#define ip6_nxt ip6_ctlun.ip6_un1.ip6_un1_nxt
#define ip6_hlim ip6_ctlun.ip6_un1.ip6_un1_hlim
#define ip6_hops ip6_ctlun.ip6_un1.ip6_un1_hlim

struct ip6_ext {
    uint8_t ip6e_nxt;
    uint8_t ip6e_len;
};

struct ip6_hbh {
    uint8_t ip6h_nxt;
    uint8_t ip6h_len;
};

struct ip6_dest {
    uint8_t ip6d_nxt;
    uint8_t ip6d_len;
};

struct ip6_rthdr {
    uint8_t ip6r_nxt;
    uint8_t ip6r_len;
    uint8_t ip6r_type;
    uint8_t ip6r_segleft;
};

struct ip6_rthdr0 {
    uint8_t ip6r0_nxt;
    uint8_t ip6r0_len;
    uint8_t ip6r0_type;
    uint8_t ip6r0_segleft;
    uint8_t ip6r0_reserved;
    uint8_t ip6r0_slmap[3];
    struct in6_addr ip6r0_addr[];
};

struct ip6_frag {
    uint8_t ip6f_nxt;
    uint8_t ip6f_reserved;
    uint16_t ip6f_offlg;
    uint32_t ip6f_ident;
};

#if __BYTE_ORDER == __BIG_ENDIAN
#define IP6F_OFF_MASK 0xfff8
#define IP6F_RESERVED_MASK 0x0006
#define IP6F_MORE_FRAG 0x0001
#else
#define IP6F_OFF_MASK 0xf8ff
#define IP6F_RESERVED_MASK 0x0600
#define IP6F_MORE_FRAG 0x0100
#endif

struct ip6_opt {
    uint8_t ip6o_type;
    uint8_t ip6o_len;
};

#define IP6OPT_TYPE(o) ((o)&0xc0)
#define IP6OPT_TYPE_SKIP 0x00
#define IP6OPT_TYPE_DISCARD 0x40
#define IP6OPT_TYPE_FORCEICMP 0x80
#define IP6OPT_TYPE_ICMP 0xc0
#define IP6OPT_TYPE_MUTABLE 0x20

#define IP6OPT_PAD1 0
#define IP6OPT_PADN 1

#define IP6OPT_JUMBO 0xc2
#define IP6OPT_NSAP_ADDR 0xc3
#define IP6OPT_TUNNEL_LIMIT 0x04
#define IP6OPT_ROUTER_ALERT 0x05

struct ip6_opt_jumbo {
    uint8_t ip6oj_type;
    uint8_t ip6oj_len;
    uint8_t ip6oj_jumbo_len[4];
};
#define IP6OPT_JUMBO_LEN 6

struct ip6_opt_nsap {
    uint8_t ip6on_type;
    uint8_t ip6on_len;
    uint8_t ip6on_src_nsap_len;
    uint8_t ip6on_dst_nsap_len;
};

struct ip6_opt_tunnel {
    uint8_t ip6ot_type;
    uint8_t ip6ot_len;
    uint8_t ip6ot_encap_limit;
};

struct ip6_opt_router {
    uint8_t ip6or_type;
    uint8_t ip6or_len;
    uint8_t ip6or_value[2];
};

#if __BYTE_ORDER == __BIG_ENDIAN
#define IP6_ALERT_MLD 0x0000
#define IP6_ALERT_RSVP 0x0001
#define IP6_ALERT_AN 0x0002
#else
#define IP6_ALERT_MLD 0x0000
#define IP6_ALERT_RSVP 0x0100
#define IP6_ALERT_AN 0x0200
#endif

#ifdef __cplusplus
}
#endif