/* * Issue an ICMP address mask request and print the reply. * * This program originated from the public domain ping program written * by Mike Muuss. * * You must be superuser to run this program (or it must be suid to root) * since it requires a raw socket. */#include <sys/types.h>#include <sys/param.h>#include <sys/socket.h>#include <sys/file.h>#include <sys/time.h>#include <sys/signal.h>#include <netinet/in_systm.h>#include <netinet/in.h>#include <netinet/ip.h>#include <netinet/ip_icmp.h>#include <netinet/ip_var.h>#include <netdb.h>#include <unistd.h>#include <stdio.h>#include <ctype.h>#include <errno.h>#include <string.h>#define	DEFDATALEN	(12)	/* default data length */#define	MAXIPLEN	60#define	MAXICMPLEN	76#define	MAXPACKET	(65536 - 60 - 8)/* max packet size */struct sockaddr	whereto;	/* who to send request to */int		datalen = DEFDATALEN;int		s;u_char		outpack[MAXPACKET];char		*hostname;u_long		inet_addr();char		*inet_ntoa();void		sig_alrm(int);int		response = 0;main(argc, argv)int	argc;char	**argv;{	int			i, ch, fdmask, hold, packlen, preload;	extern int		errno;	struct hostent		*hp;	struct sockaddr_in	*to;	struct protoent		*proto;	u_char			*packet;	char			*target, hnamebuf[MAXHOSTNAMELEN], *malloc();	if (argc != 2)		exit(1);	target = argv[1];	bzero((char *)&whereto, sizeof(struct sockaddr));	to = (struct sockaddr_in *)&whereto;	to->sin_family = AF_INET;		/* try to convert as dotted decimal address,		   else if that fails assume it's a hostname */	to->sin_addr.s_addr = inet_addr(target);	if (to->sin_addr.s_addr != (u_int)-1)		hostname = target;	else {		hp = gethostbyname(target);		if (!hp) {			fprintf(stderr, "unknown host %s\n", target);			exit(1);		}		to->sin_family = hp->h_addrtype;		bcopy(hp->h_addr, (caddr_t)&to->sin_addr, hp->h_length);		strncpy(hnamebuf, hp->h_name, sizeof(hnamebuf) - 1);		hostname = hnamebuf;	}	packlen = datalen + MAXIPLEN + MAXICMPLEN;	if ( (packet = (u_char *)malloc((u_int)packlen)) == NULL) {		fprintf(stderr, "malloc error\n");		exit(1);	}	if ( (proto = getprotobyname("icmp")) == NULL) {		fprintf(stderr, "unknown protocol icmp\n");		exit(1);	}	if ( (s = socket(AF_INET, SOCK_RAW, proto->p_proto)) < 0) {		perror("socket");	/* probably not running as superuser */		exit(1);	}	/*	 * We send one request, then wait 5 seconds, printing any	 * replies that come back.  This lets us send a request to	 * a broadcast address and print multiple replies.	 */	signal(SIGALRM, sig_alrm);	alarm(5);	/* 5 second time limit */	sender();	/* send the request */	for (;;) {		struct sockaddr_in	from;		int			cc, fromlen;		fromlen = sizeof(from);		if ( (cc = recvfrom(s, (char *)packet, packlen, 0,		    		    (struct sockaddr *)&from, &fromlen)) < 0) {			if (errno == EINTR)				continue;			perror("recvfrom error");			continue;		}		procpack((char *)packet, cc, &from);	}}/* * Send the ICMP address mask request. */sender(){	int		i, cc;	struct icmp	*icp;	icp = (struct icmp *)outpack;	icp->icmp_type = ICMP_MASKREQ;	icp->icmp_code = 0;	icp->icmp_cksum = 0;	/* compute checksum below */	icp->icmp_seq = 12345;	/* seq and id must be reflected */	icp->icmp_id = getpid();	icp->icmp_mask = 0;	cc = ICMP_MASKLEN;	/* 12 = 8 bytes of header, 4 bytes of mask */		/* compute ICMP checksum here */	icp->icmp_cksum = in_cksum((u_short *)icp, cc);	i = sendto(s, (char *)outpack, cc, 0, &whereto,	    				sizeof(struct sockaddr));	if (i < 0 || i != cc)  {		if (i < 0)			perror("sendto error");		printf("wrote %s %d chars, ret=%d\n", hostname, cc, i);	}}/* * Process a received ICMP message. */procpack(buf, cc, from)char			*buf;int			cc;struct sockaddr_in	*from;{	int		i, hlen;	struct icmp	*icp;	struct ip	*ip;	struct timeval	tvdelta;		/* Check the IP header */	ip = (struct ip *)buf;	hlen = ip->ip_hl << 2;	if (cc < hlen + ICMP_MINLEN) {		fprintf(stderr, "packet too short (%d bytes) from %s\n", cc,			  inet_ntoa(*(struct in_addr *)&from->sin_addr.s_addr));		return;	}		/* Now the ICMP part */	cc -= hlen;	icp = (struct icmp *)(buf + hlen);		/* With a raw ICMP socket we get all ICMP packets that		   come into the kernel. */	if (icp->icmp_type == ICMP_MASKREPLY) {		if (cc != ICMP_MASKLEN)			printf("cc = %d, expected cc = 12\n", cc);		if (icp->icmp_seq != 12345)			printf("received sequence # %d\n", icp->icmp_seq);		if (icp->icmp_id != getpid())			printf("received id %d\n", icp->icmp_id);		printf("received mask = %08x, from %s\n",			ntohl(icp->icmp_mask),			inet_ntoa(*(struct in_addr *) &from->sin_addr.s_addr));		response++;	}	/* We ignore all other types of ICMP messages */}/* * in_cksum -- *	Checksum routine for Internet Protocol family headers (C Version) */in_cksum(addr, len)	u_short *addr;	int len;{	register int nleft = len;	register u_short *w = addr;	register int sum = 0;	u_short answer = 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) {		*(u_char *)(&answer) = *(u_char *)w ;		sum += answer;	}	/* add back carry outs from top 16 bits to low 16 bits */	sum = (sum >> 16) + (sum & 0xffff);	/* add hi 16 to low 16 */	sum += (sum >> 16);			/* add carry */	answer = ~sum;				/* truncate to 16 bits */	return(answer);}voidsig_alrm(int signo){	if (response == 0) {		printf("timeout\n");		exit(1);	}	exit(0);	/* we got one or more responses */}