/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   icmp.c                                             :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: tomoron <tomoron@student.42angouleme.fr>   +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2025/04/24 22:49:22 by tomoron           #+#    #+#             */
/*   Updated: 2025/04/30 17:53:19 by tomoron          ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */
#include "includes/ft_ping.h"

static void set_packet_data(uint8_t *packet_data)
{
	int i;

	i = 0;
	while(i < PACKET_DATA_LENGTH)
	{
		packet_data[i] = i;
		i++;
	}
}

uint16_t calc_checksum(void *ptr, size_t len)
{
	uint32_t		res;
	uint16_t		*data;

	data = ptr;
	res = 0;
	while (len > 1)
	{
		res += *data;
		data++;
		len -= 2;	
	}
	if (len)
		res += *(uint8_t *)data;

	while (res >> 16) {
        res = (res & 0xFFFF) + (res >> 16);
    }
	
	return(~res);
}

t_icmp_echo prepare_icmp_echo(uint16_t sequence, uint16_t identifier)
{
	t_icmp_echo packet;

	packet.type = 8;
	packet.code = 0;
	packet.identifier = htons(identifier);
	packet.sequence = htons(sequence);
	set_packet_data(packet.data);
	gettimeofday(&packet.time, 0);

	packet.checksum = 0;
	packet.checksum = calc_checksum(&packet, sizeof(t_icmp_echo));

	return(packet);
}