#ifndef _VXLAN_H
#define _VXLAN_H

#ifdef __cpluscplus
extern "C"
{
#endif

#define __FAVOR_BSD 1
#include <netinet/udp.h>

#include "tuple.h"

/*
 * VXLAN Header:
 *
 *   0                   1                   2                   3
 *   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |R|R|R|R|I|R|R|R|            Reserved                           |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |                VXLAN Network Identifier (VNI) |   Reserved    |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * Flags (8 bits):
 *       where the I flag MUST be set to 1 for a valid VXLAN Network ID (VNI).
 *       The other 7 bits (designated "R") are reserved fields and MUST be set
 *       to zero on transmission and ignored on receipt.
 * Reserved fields (24 bits and 8 bits):
 *       MUST be set to zero on transmission and ignored on receipt.
 */

struct vxlan_hdr
{
	uint8_t flags;
	uint8_t reserved[3];

	// VNI 3 Bytes
	uint8_t vlan_id_half_high;

	uint8_t link_layer_type : 4; // 二层报文封装格式
	uint8_t vlan_id_half_low : 4;

	uint8_t dir : 1;
	uint8_t traffic : 1;
	uint8_t sf_index : 5; // max value 32
	uint8_t online_test : 1;

	// Reserved 1 Bytes
	uint8_t r7 : 1;
	uint8_t r6 : 1;
	uint8_t r5 : 1;
	uint8_t r4 : 1;
	uint8_t vni_flag : 1;
	uint8_t r2 : 1;
	uint8_t r1 : 1;
	uint8_t r0 : 1;
} __attribute__((__packed__));

enum vni_opt
{
	VNI_OPT_DIR = 0x80,
	VNI_OPT_TRAFFIC = 0x40,
	VNI_OPT_SFINDEX = 0x3f,
};

#define VXLAN_FLAGS 0x8
#define VXLAN_DST_PORT 4789
#define VXLAN_FRAME_HDR_LEN (sizeof(struct ethhdr) + sizeof(struct ip) + sizeof(struct udphdr) + sizeof(struct vxlan_hdr))

void vxlan_set_opt(struct vxlan_hdr *hdr, enum vni_opt opt, uint8_t val);
uint8_t vxlan_get_opt(struct vxlan_hdr *hdr, enum vni_opt opt);

// return  0 : success
// return -1 : error
int vxlan_frame_decode(struct vxlan_hdr **vxlan_hdr, const char *data, uint16_t len);
void vxlan_frame_encode(char *buff,
						const u_char eth_src_mac[], const u_char eth_dst_mac[],
						const in_addr_t ip_src_addr, const in_addr_t ip_dst_addr, uint16_t ip_id,
						uint16_t udp_src_port, uint16_t udp_pld_len,
						uint8_t vni_opt_dir, uint8_t vni_opt_traffic, uint8_t vni_opt_sf_index);

uint16_t calculate_vxlan_source_port(struct four_tuple *innermost_tuple4);

#ifdef __cpluscplus
}
#endif

#endif