/*
ping.c

pings a host and gives stats on interupt
only takes ip addresses
have to be setuid for raw socket
drops privs after getting socket

tgo - http://anomalous-security.org
*/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <signal.h>

#include <sys/socket.h>
#include <sys/types.h>

#include <netinet/in.h>
#include <netinet/ip_icmp.h>
#include <netinet/ip.h>

#define DATALEN 56
#define PACKETSIZE 1500

int sent  = 0;
int received = 0;

struct icmp *icmp;
char packet[PACKETSIZE+1];
int sock;
char *host;


void die(char *reason){
   perror(reason);
   exit(1);
}

void usage(char *prog){
   printf("%s <ip address>\n",prog);
   exit(1);   
}

/* stolen - everyone does it */
in_cksum(addr, len)
u_short *addr;
int len;
{
   register int nleft = len;
   register u_short *w = addr;
   register int sum = 0;

   /*
    *  Our algorithm is simple, using a 32 bit accumulator (sum),
    *  we add sequential 16 bit words to it, and at the end, fold
    *  back all the carry bits from the top 16 bits into the lower
    *  16 bits.
    */
   while( nleft > 1 )  {
      sum += *w++;
      nleft -= 2;
   }

   /* mop up an odd byte, if necessary */
   if( nleft == 1 )
      sum += *(u_char *)w;

   /*
    * add back carry outs from top 16 bits to low 16 bits
    */
    while (sum>>16)
        sum = (sum & 0xffff) + (sum >> 16);     /* add hi 16 to low 16 */
       
   return ( (~sum) & 0xFFFF);
}

void send_request(){

   struct sockaddr    where;
   struct sockaddr_in *whereto;
   int total = DATALEN + 8;
   memset(packet,0x00,sizeof(packet));

   whereto = (struct sockaddr_in *)&where;

   whereto->sin_family = AF_INET;
   whereto->sin_addr.s_addr = inet_addr(host);

   /* fill icmp structure to ping host */
   icmp = (struct icmp *)packet;
   icmp->icmp_code = 0;
   icmp->icmp_type = ICMP_ECHO;
   icmp->icmp_seq = htons(sent);
   icmp->icmp_id = htons(0x029a + sent);
   memset(icmp->icmp_data,0x41,DATALEN);
   gettimeofday((struct timeval *) icmp->icmp_data,NULL);
      
        icmp->icmp_cksum = 0;
   icmp->icmp_cksum = in_cksum(icmp,total);

   if( sendto(sock,packet,total,0,&where,sizeof(struct sockaddr)) < 0)
      die("sendto");
   sent++;

}

void get_response(){

   memset(packet,0x00,sizeof(packet));
   read(sock,&packet,1500);
   int type;
   struct sockaddr_in source;

        struct ip *ip = (struct ip *) (packet);
   icmp = (struct icmp *)(packet + sizeof(struct ip));

   type = icmp->icmp_type;
   
   if (type == ICMP_ECHOREPLY){
   
      received++;
   
      memcpy(&source.sin_addr, (struct sockaddr_in *)&ip->ip_src , sizeof(source.sin_addr) );

      printf("reply from: %s, id %d, sequence %d, length %d, ttl %d, type %d\n"
         ,inet_ntoa(source.sin_addr.s_addr)
         ,htons(icmp->icmp_id)
         ,htons(icmp->icmp_seq)
         ,htons(ip->ip_len)
         ,(short)ip->ip_ttl
         ,type
      );
      
   }
   else if ( type != ICMP_ECHO )
      printf("Error code %d received - check /usr/include/netinet/ip_icmp.h for value\n",type);


}

void alarm_called(int signo){

   /* sends ping request then sets alarm to go off one second later ( send another ping ) */
   send_request();
   alarm(1);
}

void print_stats(){

   /* called on SIGINT, print stats and exits */

   if (sent > 0){
      printf(
         "\n\n--- Stats for: %s ---\n"
         "Sent: %d\n"
         "Received: %d\n"
         "Percent: %d% returned\n"
         "---------------------\n"
         ,inet_ntoa(inet_addr(host))
         ,sent
         ,received
         ,(received/sent)*100
      );
   }else
      printf("no packets sent yet\n");
      
   exit(0);
}

int get_sock(){

   /* set socket and drop privs after getting socket */
   int sock;

   if((sock = socket(AF_INET,SOCK_RAW,IPPROTO_ICMP)) < 0)
      die("socket");

   setuid(getuid());

   return sock;
}
   
int main(int argc,char *argv[]){

   if (argc < 2) usage(argv[0]);

   /* set socket and host */
   sock = get_sock();   
   host = argv[1];

   /* sigalarm does 1 second interval pings */
   if ( signal(SIGALRM,alarm_called)  < 0 )
      die("signal");

   /* on control+c ( interupt ) print stats and exit */
   if ( signal(SIGINT,print_stats) < 0 )
      die("signal");

   /* signal alarm for first packet */
   alarm(1);

   /* keep reading responses */
   while(1) get_response();
}