/*
 * Copyright (c) 1999 - 2002
 *  Politecnico di Torino.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the Politecnico
 * di Torino, and its contributors.'' Neither the name of
 * the University nor the names of its contributors may be used to endorse
 * or promote products derived from this software without specific prior
 * written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include "pcap.h"

/* 4 bytes IP address */
typedef struct ip_address{
    u_char byte1;
    u_char byte2;
    u_char byte3;
    u_char byte4;
}ip_address;

/* IPv4 header */
typedef struct ip_header{
    u_char  ver_ihl;        // Version (4 bits) + Internet header length (4 bits)
    u_char  tos;            // Type of service 
    u_short tlen;           // Total length 
    u_short identification; // Identification
    u_short flags_fo;       // Flags (3 bits) + Fragment offset (13 bits)
    u_char  ttl;            // Time to live
    u_char  proto;          // Protocol
    u_short crc;            // Header checksum
    ip_address  saddr;      // Source address
    ip_address  daddr;      // Destination address
    u_int   op_pad;         // Option + Padding
}ip_header;

/* UDP header*/
typedef struct udp_header{
    u_short sport;          // Source port
    u_short dport;          // Destination port
    u_short len;            // Datagram length
    u_short crc;            // Checksum
}udp_header;


/* prototype of the packet handler */
void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data);

main()
{
    pcap_if_t *alldevs;
    pcap_if_t *d;
    int inum;
    int i=0;
    pcap_t *adhandle;
    char errbuf[PCAP_ERRBUF_SIZE];

  
    /* Retrieve the device list */
    if (pcap_findalldevs(&alldevs, errbuf) == -1)
    {
        fprintf(stderr,"Error in pcap_findalldevs: %s\n", errbuf);
        exit(1);
    }
    
    /* Print the list */
    for(d=alldevs; d; d=d->next)
    {        
        if (d->description)
            printf("%d (%s)\n",++i, d->description);
        else
            printf("%d. %s", ++i, d->name);
    }

    if(i==0)
    {
        printf("\nNo interfaces found! Make sure WinPcap is installed.\n");
        return -1;
    }
    
    printf("Enter the interface number (1-%d):",i);
    scanf("%d", &inum);
    
    if(inum < 1 || inum > i)
    {
        printf("\nInterface number out of range.\n");
        /* Free the device list */
        pcap_freealldevs(alldevs);
        return -1;
    }

    /* Jump to the selected adapter */
    for(d=alldevs, i=0; i< inum-1 ;d=d->next, i++);
    
    /* Open the adapter */
    if ( (adhandle= pcap_open_live(d->name, // name of the device
                             65536,     // portion of the packet to capture. 
                                        // 65536 grants that the whole packet will be captured on all the MACs.
                             1,         // promiscuous mode
                             1000,      // read timeout
                             errbuf     // error buffer
                             ) ) == NULL)
    {
        fprintf(stderr,"\nUnable to open the adapter. %s is not supported by WinPcap\n");
        /* Free the device list */
        pcap_freealldevs(alldevs);
        return -1;
    }
    
    /* Check the link layer. We support only Ethernet for simplicity. */
    if(pcap_datalink(adhandle) != DLT_EN10MB)
    {
        fprintf(stderr,"\nThis program works only on Ethernet networks.\n");
        /* Free the device list */
        pcap_freealldevs(alldevs);
        return -1;
    }

	printf("Works only correct for packes formated: Ethernet, IP, UDP");
    printf("\nlistening on %s...\n", d->description);
    
    /* At this point, we don't need any more the device list. Free it */
    pcap_freealldevs(alldevs);
    
    /* start the capture */
    pcap_loop(adhandle, 0, packet_handler, NULL);
    
    return 0;
}

/* Callback function invoked by libpcap for every incoming packet */
void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data)
{	
	int brutto;
	int netto;
	double anteil;
	u_char ch;
	int begin=0;
	int end=0;
	int i;
	ip_header *ih;
    udp_header *uh;
    u_int ip_len;
    u_short sport,dport;

	brutto = header->len;	//length of the packet

	netto=brutto-(14+20+8);
	anteil = ((double)netto/brutto)*100;
	

    // print statistic out 
	printf("Brutto:\t%d\tNetto:\t%d\tNutzdaten:\t%f %%\n", brutto,netto,anteil);

    // retireve the position of the ip header 
    ih = (ip_header *) (pkt_data +
        14); //length of ethernet header

    // retireve the position of the udp header 
    ip_len = (ih->ver_ihl & 0xf) * 4;
    uh = (udp_header *) ((u_char*)ih + ip_len);

    // convert from network byte order to host byte order 
    sport = ntohs( uh->sport );
    dport = ntohs( uh->dport );

    // print ip addresses and udp ports 
	printf("From: %d.%d.%d.%d.%d\n",
        ih->saddr.byte1,
        ih->saddr.byte2,
        ih->saddr.byte3,
        ih->saddr.byte4,
        sport
        );
//	printf("%s\n",&pkt_data[brutto-netto]);
}