/*
 * (c) spd@daphne.cps.unizar.es
 *
 * sid: a program which changes/restores hostid on little endian linux hosts
 *
 * change hostid:
 *     sid 0xffffffff
 * restore original hostid:
 *     sid
 */


#include <stdio.h>
#include <unistd.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

#include <errno.h>

#ifndef INADDR_NONE
#define INADDR_NONE     0xffffffff
#endif


/*

Real example:
(Linux Red Hat 6.2)

inet addr:155.210.152.24
hostid: 0xd29b1898

155 -> 9b
210 -> d2
152 -> 98
24  -> 18

*/

int main(int argc, char **argv)
{
	long int hostid;
	char hostname[256];
	struct hostent  *he;
	u_long	add;


	if (argc != 1)
	{
		printf("current hostid: 0x%x\n", gethostid());
		printf("sethostid: %ld %d\n",
			strtol( argv[1], (char **)NULL, 0 ),
			sethostid(strtol( argv[1], (char **)NULL, 0 )));
		printf("current hostid: %x\n", gethostid());
	}
	else
	{
		/*
		 * We will get IP from hostname instead of querying network
		 * interface. If you don't like it, edit below this line...
		 */
		if (gethostname(hostname,sizeof(hostname)) < 0)
		{
			perror("gethostname: who am I ?");
			exit(1);
		}
		if ( (he=gethostbyname(hostname)) == NULL)
		{
			perror("gethostbyname: can't get an address");
			exit(1);
		}
		add=htonl( ((struct in_addr *)(he->h_addr_list[0]))->s_addr );

		hostid= (
		((add & 0xff000000)>>8)|
		((add & 0x00ff0000)<<8)|
		((add & 0x0000ff00)>>8)|
		((add & 0x000000ff)<<8)
		);

		printf("sethostid: 0x%lx %d\n", hostid, sethostid(hostid));
	}
	return (0);
}