/**
 * Destiny UDP implementation 
 *
 * Copyright (C) 2013  INRIA.
 *
 * This file subject to the terms and conditions of the GNU Lesser General
 * Public License. See the file LICENSE in the top level directory for more
 * details.
 *
 * @ingroup destiny 
 * @{
 * @file    udp.c
 * @brief   UDP implementation 
 * @author  Oliver Gesch <oliver.gesch@googlemail.com>
 * @}
 */


#include <stdio.h>
#include <thread.h>
#include <string.h>

#include "udp.h"
#include "msg.h"
#include "../sixlowpan/sixlowip.h"
#include "../sixlowpan/sixlowpan.h"
#include "socket.h"
#include "in.h"
#include "../net_help/net_help.h"
#include "../net_help/msg_help.h"

uint16_t udp_csum(ipv6_hdr_t *ipv6_header, udp_hdr_t *udp_header)
{
    uint16_t sum;
    uint16_t len = udp_header->length;

    sum = len + IPPROTO_UDP;
    sum = csum(sum, (uint8_t *)&ipv6_header->srcaddr, 2 * sizeof(ipv6_addr_t));
    sum = csum(sum, (uint8_t *)udp_header, len);
    return (sum == 0) ? 0xffff : HTONS(sum);
}

void udp_packet_handler(void)
{
    msg_t m_recv_ip, m_send_ip, m_recv_udp, m_send_udp;
    ipv6_hdr_t *ipv6_header;
    udp_hdr_t *udp_header;
    uint8_t *payload;
    socket_internal_t *udp_socket = NULL;
    uint16_t chksum;

    while (1) {
        msg_receive(&m_recv_ip);
        ipv6_header = ((ipv6_hdr_t *)m_recv_ip.content.ptr);
        udp_header = ((udp_hdr_t *)(m_recv_ip.content.ptr + IPV6_HDR_LEN));
        payload = (uint8_t *)(m_recv_ip.content.ptr + IPV6_HDR_LEN + UDP_HDR_LEN);

        chksum = udp_csum(ipv6_header, udp_header);

        if (chksum == 0xffff) {
            udp_socket = get_udp_socket(ipv6_header, udp_header);

            if (udp_socket != NULL) {
                m_send_udp.content.ptr = (char *)ipv6_header;
                msg_send_receive(&m_send_udp, &m_recv_udp, udp_socket->recv_pid);
            }
            else {
                printf("Dropped UDP Message because no thread ID was found for delivery!\n");
            }
        }
        else {
            printf("Wrong checksum (%x)!\n", chksum);
        }

        msg_reply(&m_recv_ip, &m_send_ip);
    }
}