ping.c

This is a short linux ping program

		     inet_ntoa(whereto.sin_addr), datalen);

	/* When pinging the broadcast address, you can get a lot
	 * of answers.  Doing something so evil is useful if you
	 * are trying to stress the ethernet, or just want to
	 * fill the arp cache to get some stuff for /etc/ethers.
	 */
	while (0 > setsockopt(s, SOL_SOCKET, SO_RCVBUF,
			      (char*)&bufspace, sizeof(bufspace))) {
		if ((bufspace -= 4096) <= 0)
			err(1, "Cannot set the receive buffer size");
	}

	/* make it possible to send giant probes, but do not worry now
	 * if it fails, since we probably won't send giant probes.
	 */
	(void)setsockopt(s, SOL_SOCKET, SO_SNDBUF,
			 (char*)&bufspace, sizeof(bufspace));

	(void)signal(SIGINT, prefinish);

#if defined(SIGINFO) && defined(NOKERNINFO)
	if (tcgetattr (0, &ts) != -1) {
		reset_kerninfo = !(ts.c_lflag & NOKERNINFO);
		ts.c_lflag |= NOKERNINFO;
		tcsetattr (STDIN_FILENO, TCSANOW, &ts);
	}
#endif

#ifdef SIGINFO
	(void)signal(SIGINFO, prtsig);
#else
	(void)signal(SIGQUIT, prtsig);
#endif
	(void)signal(SIGCONT, prtsig);

	/* fire off them quickies */
	for (i = 0; i < preload; i++) {
		(void)gettimeofday(&now, 0);
		pinger();
	}

	doit();
	return 0;
}


static void
doit(void)
{
	int cc;
	struct sockaddr_in from;
	int fromlen;
	double sec, last, d_last;
	struct pollfd fdmaskp[1];

	(void)gettimeofday(&clear_cache,0);
	if (maxwait != 0) {
		last = timeval_to_sec(&clear_cache) + maxwait;
		d_last = 0;
	} else {
		last = 0;
		d_last = 365*24*60*60;
	}

	do {
		(void)gettimeofday(&now,0);

		if (last != 0)
			d_last = last - timeval_to_sec(&now);

		if (ntransmitted < npackets && d_last > 0) {
			/* send if within 100 usec or late for next packet */
			sec = diffsec(&next_tx,&now);
			if (sec <= 0.0001 ||
			    (lastrcvd && (pingflags & F_FLOOD))) {
				pinger();
				sec = diffsec(&next_tx,&now);
			}
			if (sec < 0.0)
				sec = 0.0;
			if (d_last < sec)
				sec = d_last;

		} else {
			/* For the last response, wait twice as long as the
			 * worst case seen, or 10 times as long as the
			 * maximum interpacket interval, whichever is longer.
			 */
			sec = MAX(2 * tmax, 10 * interval) -
			    diffsec(&now, &last_tx);
			if (d_last < sec)
				sec = d_last;
			if (sec <= 0)
				break;
		}


		fdmaskp[0].fd = s;
		fdmaskp[0].events = POLLIN;
		cc = poll(fdmaskp, 1, (int)(sec * 1000));
		if (cc <= 0) {
			if (cc < 0) {
				if (errno == EINTR)
					continue;
				jiggle_flush(1);
				err(1, "poll");
			}
			continue;
		}

		fromlen  = sizeof(from);
		cc = recvfrom(s, (char *) packet, packlen,
			      0, (struct sockaddr *)&from,
			      &fromlen);
		if (cc < 0) {
			if (errno != EINTR) {
				jiggle_flush(1);
				warn("recvfrom");
				(void)fflush(stderr);
			}
			continue;
		}
		(void)gettimeofday(&now, 0);
		pr_pack(packet, cc, &from);

	} while (nreceived < npackets
		 && (nreceived == 0 || !(pingflags & F_ONCE)));

	finish(0);
}


static void
jiggle_flush(int nl)			/* new line if there are dots */
{
	int serrno = errno;

	if (jiggle_cnt > 0) {
		total_jiggled += jiggle_cnt;
		jiggle_direction = 1;
		do {
			(void)putchar('.');
		} while (--jiggle_cnt > 0);

	} else if (jiggle_cnt < 0) {
		total_jiggled -= jiggle_cnt;
		jiggle_direction = -1;
		do {
			(void)putchar('\b');
		} while (++jiggle_cnt < 0);
	}

	if (nl) {
		if (total_jiggled != 0)
			(void)putchar('\n');
		total_jiggled = 0;
		jiggle_direction = -1;
	}

	(void)fflush(stdout);
	(void)fflush(stderr);
	jiggle_time = now;
	errno = serrno;
}


/* jiggle the cursor for flood-ping
 */
static void
jiggle(int delta)
{
	double dt;

	if (pingflags & F_QUIET)
		return;

	/* do not back up into messages */
	if (total_jiggled+jiggle_cnt+delta < 0)
		return;

	jiggle_cnt += delta;

	/* flush the FLOOD dots when things are quiet
	 * or occassionally to make the cursor jiggle.
	 */
	dt = diffsec(&last_tx, &jiggle_time);
	if (dt > 0.2 || (dt >= 0.15 && delta*jiggle_direction < 0))
		jiggle_flush(0);
}


/*
 * Compose and transmit an ICMP ECHO REQUEST packet.  The IP packet
 * will be added on by the kernel.  The ID field is our UNIX process ID,
 * and the sequence number is an ascending integer.  The first PHDR_LEN bytes
 * of the data portion are used to hold a UNIX "timeval" struct in VAX
 * byte-order, to compute the round-trip time.
 */
static void
pinger(void)
{
	struct tv32 tv32;
	int i, cc, sw;

	opack_icmp.icmp_code = 0;
	opack_icmp.icmp_seq = htons((u_int16_t)(ntransmitted));

	/* clear the cached route in the kernel after an ICMP
	 * response such as a Redirect is seen to stop causing
	 * more such packets.  Also clear the cached route
	 * periodically in case of routing changes that make
	 * black holes come and go.
	 */
	if (clear_cache.tv_sec != now.tv_sec) {
		opack_icmp.icmp_type = ICMP_ECHOREPLY;
		opack_icmp.icmp_id = ~ident;
		opack_icmp.icmp_cksum = 0;
		opack_icmp.icmp_cksum = in_cksum((u_int16_t *)&opack_icmp,
		    PHDR_LEN);
		sw = 0;
		if (setsockopt(sloop,IPPROTO_IP,IP_HDRINCL,
			       (char *)&sw,sizeof(sw)) < 0)
			err(1, "Can't turn off special IP header");
		if (sendto(sloop, (char *) &opack_icmp, PHDR_LEN, MSG_DONTROUTE,
			   (struct sockaddr *)&loc_addr,
			   sizeof(struct sockaddr_in)) < 0) {
			/*
			 * XXX: we only report this as a warning in verbose
			 * mode because people get confused when they see
			 * this error when they are running in single user
			 * mode and they have not configured lo0
			 */
			if (pingflags & F_VERBOSE)
				warn("failed to clear cached route");
		}
		sw = 1;
		if (setsockopt(sloop,IPPROTO_IP,IP_HDRINCL,
			       (char *)&sw, sizeof(sw)) < 0)
			err(1, "Can't set special IP header");
		
		(void)gettimeofday(&clear_cache,0);
	}

	opack_icmp.icmp_type = ICMP_ECHO;
	opack_icmp.icmp_id = ident;
	tv32.tv32_sec = htonl(now.tv_sec);
	tv32.tv32_usec = htonl(now.tv_usec);
	if (pingflags & F_TIMING)
		(void) memcpy(&opack_icmp.icmp_data[0], &tv32, sizeof(tv32));
	cc = datalen + PHDR_LEN;
	opack_icmp.icmp_cksum = 0;
	opack_icmp.icmp_cksum = in_cksum((u_int16_t *)&opack_icmp, cc);

	cc += opack_ip->ip_hl<<2;
	opack_ip->ip_len = cc;
	i = sendto(s, (char *) opack_ip, cc, 0,
		   (struct sockaddr *)&send_addr, sizeof(struct sockaddr_in));
	if (i != cc) {
		jiggle_flush(1);
		if (i < 0)
			warn("sendto");
		else
			warnx("wrote %s %d chars, ret=%d", hostname, cc, i);
		(void)fflush(stderr);
	}
	lastrcvd = 0;

	CLR(ntransmitted);
	ntransmitted++;

	last_tx = now;
	if (next_tx.tv_sec == 0) {
		first_tx = now;
		next_tx = now;
	}

	/* Transmit regularly, at always the same microsecond in the
	 * second when going at one packet per second.
	 * If we are at most 100 ms behind, send extras to get caught up.
	 * Otherwise, skip packets we were too slow to send.
	 */
	if (diffsec(&next_tx, &now) <= interval) {
		do {
			timevaladd(&next_tx, &interval_tv);
		} while (diffsec(&next_tx, &now) < -0.1);
	}

	if (pingflags & F_FLOOD)
		jiggle(1);

	/* While the packet is going out, ready buffer for the next
	 * packet. Use a fast but not very good random number generator.
	 */
	if (pingflags & F_PING_RANDOM)
		rnd_fill();
}


static void
pr_pack_sub(int cc,
	    char *addr,
	    int seqno,
	    int dupflag,
	    int ttl,
	    double triptime)
{
	jiggle_flush(1);

	if (pingflags & F_FLOOD)
		return;

	(void)printf("%d bytes from %s: icmp_seq=%u", cc, addr, seqno);
	if (dupflag)
		(void)printf(" DUP!");
	(void)printf(" ttl=%d", ttl);
	if (pingflags & F_TIMING)
		(void)printf(" time=%.3f ms", triptime*1000.0);

	/*
	 * Send beep to stderr, since that's more likely than stdout
	 * to go to a terminal..
	 */
	if (pingflags & F_AUDIBLE && !dupflag)
		(void)fprintf(stderr,"\a");
}


/*
 * Print out the packet, if it came from us.  This logic is necessary
 * because ALL readers of the ICMP socket get a copy of ALL ICMP packets
 * which arrive ('tis only fair).  This permits multiple copies of this
 * program to be run without having intermingled output (or statistics!).
 */
static void
pr_pack(u_char *buf,
	int tot_len,
	struct sockaddr_in *from)
{
	struct ip *ip;
	struct icmp *icp;
	int i, j, net_len;
	u_char *cp;
	static int old_rrlen;
	static char old_rr[MAX_IPOPTLEN];
	int hlen, dupflag = 0, dumped;
	double triptime = 0.0;
#define PR_PACK_SUB() {if (!dumped) {			\
	dumped = 1;					\
	pr_pack_sub(net_len, inet_ntoa(from->sin_addr),	\
		    ntohs((u_int16_t)icp->icmp_seq),	\
		    dupflag, ip->ip_ttl, triptime);}}

	/* Check the IP header */
	ip = (struct ip *) buf;
	hlen = ip->ip_hl << 2;
	if (tot_len < hlen + ICMP_MINLEN) {
		if (pingflags & F_VERBOSE) {
			jiggle_flush(1);
			(void)printf("packet too short (%d bytes) from %s\n",
				     tot_len, inet_ntoa(from->sin_addr));
		}
		return;
	}

	/* Now the ICMP part */
	dumped = 0;
	net_len = tot_len - hlen;
	icp = (struct icmp *)(buf + hlen);
	if (icp->icmp_type == ICMP_ECHOREPLY
	    && icp->icmp_id == ident) {
		if (icp->icmp_seq == htons((u_int16_t)(ntransmitted-1)))
			lastrcvd = 1;
		last_rx = now;
		if (first_rx.tv_sec == 0)
			first_rx = last_rx;
		nreceived++;
		if (pingflags & F_TIMING) {
			struct timeval tv;
			struct tv32 tv32;

			(void) memcpy(&tv32, icp->icmp_data, sizeof(tv32));
			tv.tv_sec = ntohl(tv32.tv32_sec);
			tv.tv_usec = ntohl(tv32.tv32_usec);
			triptime = diffsec(&last_rx, &tv);
			tsum += triptime;
			tsumsq += triptime * triptime;
			if (triptime < tmin)
				tmin = triptime;
			if (triptime > tmax)
				tmax = triptime;
		}

		if (TST(ntohs((u_int16_t)icp->icmp_seq))) {
			nrepeats++, nreceived--;
			dupflag=1;
		} else {
			SET(ntohs((u_int16_t)icp->icmp_seq));
		}

		if (tot_len != opack_ip->ip_len) {
			PR_PACK_SUB();
			(void)printf("\nwrong total length %d instead of %d",
				     tot_len, opack_ip->ip_len);
		}

		if (!dupflag) {
			static u_int16_t last_seqno = 0xffff;
			u_int16_t seqno = ntohs((u_int16_t)icp->icmp_seq);
			u_int16_t gap = seqno - (last_seqno + 1);
			if (gap > 0 && gap < 0x8000 &&
			    (pingflags & F_VERBOSE)) {
				(void)printf("[*** sequence gap of %u "
				    "packets from %u ... %u ***]\n", gap,
				    (u_int16_t) (last_seqno + 1),
				    (u_int16_t) (seqno - 1));
				if (pingflags & F_QUIET)
					summary(0);
			}

			if (gap < 0x8000)
				last_seqno = seqno;
		}

		if (pingflags & F_QUIET)
			return;

		if (!(pingflags & F_FLOOD))
			PR_PACK_SUB();

		/* check the data */
		if (datalen > PHDR_LEN
		    && !(pingflags & F_PING_RANDOM)
		    && memcmp(&icp->icmp_data[PHDR_LEN],
			    &opack_icmp.icmp_data[PHDR_LEN],
			    datalen-PHDR_LEN)) {
			for (i=PHDR_LEN; i<datalen; i++) {
				if (icp->icmp_data[i] !=
				    opack_icmp.icmp_data[i])
					break;
			}
			PR_PACK_SUB();
			(void)printf("\nwrong data byte #%d should have been"
				     " %#x but was %#x", i,
				     (u_char)opack_icmp.icmp_data[i],
				     (u_char)icp->icmp_data[i]);
			for (i=PHDR_LEN; i<datalen; i++) {
				if ((i%16) == PHDR_LEN)
					(void)printf("\n\t");
				(void)printf("%2x ",(u_char)icp->icmp_data[i]);
			}
		}

	} else {
		if (!pr_icmph(icp, from, net_len))
			return;
		dumped = 2;
	}

	/* Display any IP options */
	cp = buf + sizeof(struct ip);
	while (hlen > (int)sizeof(struct ip)) {
		switch (*cp) {
		case IPOPT_EOL:
			hlen = 0;
			break;
		case IPOPT_LSRR:
			hlen -= 2;
			j = *++cp;
			++cp;
			j -= IPOPT_MINOFF;
			if (j <= 0)
				continue;
			if (dumped <= 1) {
				j = ((j+3)/4)*4;
				hlen -= j;
				cp += j;
				break;
			}
			PR_PACK_SUB();
			(void)printf("\nLSRR: ");
			for (;;) {
				pr_saddr(cp);
				cp += 4;
				hlen -= 4;
				j -= 4;
				if (j <= 0)
					break;
				(void)putchar('\n');
			}
			break;
		case IPOPT_RR:
			j = *++cp;	/* get length */
			i = *++cp;	/* and pointer */
			hlen -= 2;
			if (i > j)
				i = j;
			i -= IPOPT_MINOFF;
			if (i <= 0)
				continue;
			if (dumped <= 1) {
				if (i == old_rrlen
				    && !memcmp(cp, old_rr, i)) {
					if (dumped)
					    (void)printf("\t(same route)");
					j = ((i+3)/4)*4;
					hlen -= j;
					cp += j;
					break;
				}
				old_rrlen = i;
				(void) memcpy(old_rr, cp, i);
			}
			if (!dumped) {
				jiggle_flush(1);
				(void)printf("RR: ");
				dumped = 1;
			} else {
				(void)printf("\nRR: ");
			}
			for (;;) {
				pr_saddr(cp);
				cp += 4;
				hlen -= 4;
				i -= 4;
				if (i <= 0)
					break;
				(void)putchar('\n');
			}
			break;
		case IPOPT_NOP:
			if (dumped <= 1)
				break;
			PR_PACK_SUB();
			(void)printf("\nNOP");
			break;
#ifdef sgi
		case IPOPT_SECURITY:	/* RFC 1108 RIPSO BSO */
		case IPOPT_ESO:		/* RFC 1108 RIPSO ESO */
		case IPOPT_CIPSO:	/* Commercial IPSO */
			if ((sysconf(_SC_IP_SECOPTS)) > 0) {
				i = (unsigned)cp[1];
				hlen -= i - 1;
				PR_PACK_SUB();
				(void)printf("\nSEC:");
				while (i--) {
					(void)printf(" %02x", *cp++);
				}
				cp--;
				break;
			}
#endif
		default:
			PR_PACK_SUB();
			(void)printf("\nunknown option 0x%x", *cp);
			break;
		}
		hlen--;
		cp++;
	}

	if (dumped) {
		(void)putchar('\n');
		(void)fflush(stdout);
	} else {
		jiggle(-1);
	}
}


/* Compute the IP checksum
 *	This assumes the packet is less than 32K long.
 */
static u_int16_t
in_cksum(u_int16_t *p, u_int len)
{
	u_int32_t sum = 0;
	int nwords = len >> 1;

	while (nwords-- != 0)
		sum += *p++;

	if (len & 1) {
		union {
			u_int16_t w;
			u_int8_t c[2];
		} u;
		u.c[0] = *(u_char *)p;
		u.c[1] = 0;
		sum += u.w;
	}

	/* end-around-carry */
	sum = (sum >> 16) + (sum & 0xffff);
	sum += (sum >> 16);
	return (~sum);
}


/*
 * compute the difference of two timevals in seconds
 */
static double
diffsec(struct timeval *timenow,
	struct timeval *then)
{
	return ((timenow->tv_sec - then->tv_sec)*1.0
		+ (timenow->tv_usec - then->tv_usec)/1000000.0);
}


static void
timevaladd(struct timeval *t1,
	   struct timeval *t2)
{

	t1->tv_sec += t2->tv_sec;
	if ((t1->tv_usec += t2->tv_usec) >= 1000000) {