#ifndef _PACKET_H_
#define _PACKET_H_

#include <arpa/inet.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
#include <netinet/ip_icmp.h>

#define IPPROTO_HIDE_EID 99

// IP header + IV + tag + block cipher max overhead 
#define WRAP_OVERHEAD 20 + 16 + 16 + 16 + 2

#ifndef IP_DF
#define IP_DF 0x4000            /* dont fragment flag */
#endif

#ifndef IP_MF
#define IP_MF 0x2000            /* more fragments flag */
#endif

struct packet {
    union {
        struct iphdr ip;
        struct ip6_hdr ip6;
    } hdr;
    char payload[IP_MAXPACKET]; /* payload can be this - header size, but OK */
};

// It's all our code that uses this. 12 is much more than we need to
// construct a wrapped packet at the moment.
//
// initial usage:
//   0 - wrapping ip header, including enc_size
//   1 - encrypted portion of payload, in scratch.
//   2 - unencrypted portion of payload, in recv_pkt
#define MAX_IOVS 3
struct rsp_data {
    int count;
    struct iovec iovs[MAX_IOVS];
    unsigned char scratch[IP_MAXPACKET * 2]; // somewhere easy to put results
};


static inline int packet_find_protocol( struct packet *pkt )
{
    if ( pkt->hdr.ip.version == 0x04 ) {
        return pkt->hdr.ip.protocol;
    }

    if ( pkt->hdr.ip.version == 0x06 ) {
        return pkt->hdr.ip6.ip6_nxt;
    }

    return -1;
}

void compute_ip_checksum( struct iphdr* pkt );

int wrap_packet( struct rlocs *reg, struct packet *pkt, struct rsp_data *frag1, struct rsp_data *frag2 );
int unwrap_packet( struct rlocs *reg, struct packet *pkt, struct rsp_data *out );

struct peer_context *packet_peer_context( struct rlocs *reg, struct packet *pkt, int direction );


#endif