/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   icmp.c                                             :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: tomoron <tomoron@student.42angouleme.fr>   +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2025/04/24 22:49:22 by tomoron           #+#    #+#             */
/*   Updated: 2025/05/22 22:19:36 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);
}

t_waitlist *send_icmp(t_settings *set, struct addrinfo *host, uint16_t *seq, struct timeval *last, t_stats *stats)
{
	t_icmp_echo packet;
	t_waitlist *ret;
	size_t		len;
	
	if(timediff(last) < set->interval)
		return (0);
	packet = prepare_icmp_echo(*seq, set->id);
	len = sendto(set->socket, &packet, sizeof(t_icmp_echo), 0, host->ai_addr, host->ai_addrlen);
	if(len == (size_t)-1)
	{
		perror(set->name);
		set->err = 1;
		g_stop = 1;
	}
	gettimeofday(last, 0);
	ret = malloc(sizeof(t_waitlist));
	if(!ret)
		return(0);
	ret->time = *last;	
	ret->seq = *seq;
	ret->next = 0;
	stats->sent++;
	gettimeofday(&set->last_send_time, 0);
	(*seq)++;
	return(ret);
}

void receive_icmp(t_settings *set, struct addrinfo *info, t_waitlist **wl, t_stats *stats)
{
	size_t len;
	t_icmp_ip_reply res;
	uint16_t	checksum;

	len = recvfrom(set->socket, &res, sizeof(t_icmp_ip_reply), 0, info->ai_addr, &info->ai_addrlen);

	if(len < sizeof(t_icmp_ip_reply))
		return;
	if(len == (size_t)-1 )
		return;
	if(res.icmp.type != 0 && res.icmp.identifier != set->id)
		return ;
	checksum = res.icmp.checksum;
	res.icmp.checksum = 0;
	if(calc_checksum(&res.icmp, sizeof(t_icmp_echo)) != checksum)
		return ;
	res.icmp.sequence = htons(res.icmp.sequence);
	waitlist_remove(wl, res.icmp.sequence, set, stats, res.header.ttl);
}