#ifndef ICMP_H
#define ICMP_H

#include <stdint.h>
#include <stddef.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <time.h>

/* Opaque handle type */
typedef struct icmp_handle icmp_handle_t;

/* Reply structure passed to callback */
typedef struct icmp_reply {
	uint8_t type;
	uint8_t code;
	struct in_addr from;
	uint8_t ttl;
	struct timespec timestamp;
	void *payload;
	size_t payload_len;
	void *ip_payload;
	size_t ip_payload_len;
} icmp_reply_t;

/* Offending packet structure for error messages */
typedef struct icmp_offending_packet {
	struct in_addr src;
	struct in_addr dst;
	uint8_t protocol;
	uint8_t icmp_type;
	uint8_t icmp_code;
	union {
		struct {
			uint16_t id;
			uint16_t seq;
		} echo;
		uint32_t gateway;
		struct {
			uint16_t unused;
			uint16_t mtu;
		} frag;
		uint8_t raw[4];
	} rest;
} icmp_offending_packet_t;

/* Callback type for received packets */
typedef void (*icmp_callback_t)(const icmp_reply_t *reply, void *userdata);

/* Handle lifecycle */
icmp_handle_t *icmp_create(void);
void icmp_destroy(icmp_handle_t *h);
int icmp_get_fd(const icmp_handle_t *h);

/* Send functions */
int icmp_send_raw(icmp_handle_t *h, uint8_t type, uint8_t code,
					uint32_t header_rest,
					const void *payload, size_t len, struct in_addr dest,
					uint8_t ttl);

int icmp_send_echo(icmp_handle_t *h, struct in_addr dest, uint16_t id,
					uint16_t seq, uint8_t ttl);

/* Receive function */
int icmp_process(icmp_handle_t *h, icmp_callback_t cb, void *userdata,
				size_t max_packets);

/* ID/Sequence helpers */
int icmp_reply_id_seq(const icmp_reply_t *reply, uint16_t *id,
						uint16_t *seq);

/* Error message helpers */
int icmp_error_extract_offending(const icmp_reply_t *reply,
								icmp_offending_packet_t *offending);

/* Error handling */
const char *icmp_strerror(const icmp_handle_t *h);
int icmp_should_retry(const icmp_handle_t *h);

/* Time helpers */
int icmp_get_time(struct timespec *ts);
int64_t icmp_time_diff_ns(const struct timespec *start,
							const struct timespec *end);

#endif