text: /*
  ping.c
  */
  
  #define DEBUG	1
  
  #include <sys/types.h>
  #include <errno.h>
  #include <signal.h>
  #include <net/gen/netdb.h>
  #include <sys/ioctl.h>
  #include <stdlib.h>
  #include <stdio.h>
  #include <unistd.h>
  #include <net/gen/oneCsum.h>
  #include <fcntl.h>
  #include <net/gen/in.h>
  #include <net/gen/inet.h>
  #include <net/gen/ip_hdr.h>
  #include <net/gen/icmp_hdr.h>
  #include <net/gen/ip_io.h>
  
  #define WRITE_SIZE 30
  char buffer[16*1024];
  
  int main(int argc, char *argv[]);
  
  #if DEBUG
  #define where() fprintf(stderr, "%s %d:", __FILE__, __LINE__);
  #endif
  
  #if __STDC__
  #define PROTO(x,y) x y
  #else
  #define PROTO(x,y) X ()
  #endif
  
  PROTO (int main, (int argc, char *argv[]) );
  static PROTO (void sig_hand, (int signal) );
  
  main(argc, argv)
  int argc;
  char *argv[];
  {
  	int fd, i;
  	int result, result1;
  	nwio_ipopt_t ipopt;
  	ip_hdr_t *ip_hdr;
  	int ihl;
  	icmp_hdr_t *icmp_hdr;
  	ipaddr_t dst_addr;
  	struct hostent *hostent;
  	int length;
  
  	if (argc<2 || argc>3)
  	{
  		fprintf(stderr, "Usage: %s hostname [length]\n", argv[0]);
  		exit(1);
  	}
  	hostent= gethostbyname(argv[1]);
  	if (!hostent)
  	{
  		dst_addr= inet_addr(argv[1]);
  		if (dst_addr == -1)
  		{
  			fprintf(stderr, "%s: unknown host (%s)\n",
  				argv[0], argv[1]);
  			exit(1);
  		}
  	}
  	else
  		dst_addr= *(ipaddr_t *)(hostent->h_addr);
  	if (argc == 3)
  	{
  		length= strtol (argv[2], (char **)0, 0);
  		if (length< sizeof(icmp_hdr_t) + IP_MIN_HDR_SIZE)
  		{
  			fprintf(stderr, "%s: length too small (%s)\n",
  				argv[0], argv[2]);
  			exit(1);
  		}
  	}
  	else
  		length= WRITE_SIZE;
  
  	fd= open ("/dev/ip", O_RDWR);
  	if (fd<0)
  		perror("open"), exit(1);
  
  	ipopt.nwio_flags= NWIO_COPY | NWIO_PROTOSPEC;
  	ipopt.nwio_proto= 1;
  
  	result= ioctl (fd, NWIOSIPOPT, &ipopt);
  	if (result<0)
  		perror("ioctl (NWIOSIPOPT)"), exit(1);
  
  	result= ioctl (fd, NWIOGIPOPT, &ipopt);
  	if (result<0)
  		perror("ioctl (NWIOGIPOPT)"), exit(1);
  
  	for (i= 0; i< 20; i++)
  	{
  		ip_hdr= (ip_hdr_t *)buffer;
  		ip_hdr->ih_dst= dst_addr;
  
  		icmp_hdr= (icmp_hdr_t *)(buffer+20);
  		icmp_hdr->ih_type= 8;
  		icmp_hdr->ih_code= 0;
  		icmp_hdr->ih_chksum= 0;
  		icmp_hdr->ih_chksum= ~oneC_sum(0, (u16_t *)icmp_hdr,
  			WRITE_SIZE-20);
  		result= write(fd, buffer, length);
  		if (result<0)
  		{
  			perror("write");
  			exit(1);
  		}
  		if (result != length)
  		{
  			where();
  			fprintf(stderr, "result= %d\n", result);
  			exit(1);
  		}
  
  		alarm(0);
  		signal (SIGALRM, sig_hand);
  		alarm(1);
  
  		result= read(fd, buffer, sizeof(buffer));
  		if (result>= 0 || errno != EINTR)
  			break;
  	}
  	if (i >= 20)
  	{
  		printf("no answer from %s\n", argv[1]);
  		exit(1);
  	}
  	if (result<0)
  	{
  		perror ("read");
  		exit(1);
  	}
  	printf("%s is alive\n", argv[1]);
  	exit(0);
  }
  
  static void sig_hand(signal)
  int signal;
  {
  }
  