ping.c

来自「Linux socket 编程」· C语言 代码 · 共 1,192 行 · 第 1/3 页

	ident = getpid() & 0xFFFF;
	hold = 1;

	if (options & F_SO_DEBUG)
		(void)setsockopt(s, SOL_SOCKET, SO_DEBUG, (char *)&hold,
		    sizeof(hold));

	if (options & F_SO_DONTROUTE)
		(void)setsockopt(s, SOL_SOCKET, SO_DONTROUTE, (char *)&hold,
		    sizeof(hold));

	/* this is necessary for broadcast pings to work */
	setsockopt(s, SOL_SOCKET, SO_BROADCAST, (char *)&hold, sizeof(hold));

	/* record route option */
	if (options & F_RROUTE) {
#ifdef IP_OPTIONS
	        memset(rspace, 0, sizeof(rspace));
		rspace[IPOPT_OPTVAL] = IPOPT_RR;
		rspace[IPOPT_OLEN] = sizeof(rspace)-1;
		rspace[IPOPT_OFFSET] = IPOPT_MINOFF;
		if (setsockopt(s, IPPROTO_IP, IP_OPTIONS, rspace,
		    sizeof(rspace)) < 0) {
			perror("ping: record route");
			exit(2);
		}
#else
		(void)fprintf(stderr,
		  "ping: record route not available in this implementation.\n");
		exit(2);
#endif /* IP_OPTIONS */
	}

	/*
	 * 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.
	 */
	hold = 48 * 1024;
	(void)setsockopt(s, SOL_SOCKET, SO_RCVBUF, (char *)&hold,
	    sizeof(hold));

/*#if 0*/
	if (moptions & MULTICAST_NOLOOP) {
		if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_LOOP,
							&loop, 1) == -1) {
			perror ("can't disable multicast loopback");
			exit(92);
		}
	}
	if (moptions & MULTICAST_TTL) {
		if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL,
							&ttl, 1) == -1) {
			perror ("can't set multicast time-to-live");
			exit(93);
		}
	}
	if (moptions & MULTICAST_IF) {
		if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF,
					&ifaddr, sizeof(ifaddr)) == -1) {
			perror ("can't set multicast source interface");
			exit(94);
		}
	}
/*#endif*/

	if (to->sin_family == AF_INET)
		(void)printf("PING %s (%s): %d data bytes\n", hostname,
		    inet_ntoa(*(struct in_addr *)&to->sin_addr.s_addr),
		    datalen);
	else
		(void)printf("PING %s: %d data bytes\n", hostname, datalen);

	(void)signal(SIGINT, finish);
	(void)signal(SIGALRM, catcher);

	while (preload--)		/* fire off them quickies */
		pinger();

	if ((options & F_FLOOD) == 0)
		catcher(0);		/* start things going */

	for (;;) {
		struct sockaddr_in from;
		register int cc;
		size_t fromlen;

		if (options & F_FLOOD) {
			pinger();
			timeout.tv_sec = 0;
			timeout.tv_usec = 10000;
			fdmask = 1 << s;
			if (select(s + 1, (fd_set *)&fdmask, (fd_set *)NULL,
			    (fd_set *)NULL, &timeout) < 1)
				continue;
		}
		fromlen = sizeof(from);
		if ((cc = recvfrom(s, (char *)packet, packlen, 0,
		    (struct sockaddr *)&from, &fromlen)) < 0) {
			if (errno == EINTR)
				continue;
			perror("ping: recvfrom");
			continue;
		}
		pr_pack((char *)packet, cc, &from);
		if (npackets && nreceived >= npackets)
			break;
	}
	finish(0);
	/* NOTREACHED */
	return 0;
}

/*
 * catcher --
 *	This routine causes another PING to be transmitted, and then
 * schedules another SIGALRM for 1 second from now.
 * 
 * bug --
 *	Our sense of time will slowly skew (i.e., packets will not be
 * launched exactly at 1-second intervals).  This does not affect the
 * quality of the delay and loss statistics.
 */
static void
catcher(int ignore)
{
	int waittime;

	(void)ignore;
	pinger();
	(void)signal(SIGALRM, catcher);
	if (!npackets || ntransmitted < npackets)
		alarm((u_int)interval);
	else {
		if (nreceived) {
			waittime = 2 * tmax / 1000;
			if (!waittime)
				waittime = 1;
			if (waittime > MAXWAIT)
				waittime = MAXWAIT;
		} else
			waittime = MAXWAIT;
		(void)signal(SIGALRM, finish);
		(void)alarm((u_int)waittime);
	}
}

#if !defined(__GLIBC__) || (__GLIBC__ < 2)
#define icmp_type type
#define icmp_code code
#define icmp_cksum checksum
#define icmp_id un.echo.id
#define icmp_seq un.echo.sequence
#define icmp_gwaddr un.gateway
#endif /* __GLIBC__ */

#define ip_hl ihl
#define ip_v version
#define ip_tos tos
#define ip_len tot_len
#define ip_id id
#define ip_off frag_off
#define ip_ttl ttl
#define ip_p protocol
#define ip_sum check
#define ip_src saddr
#define ip_dst daddr

/*
 * pinger --
 * 	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 8 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)
{
	register struct icmphdr *icp;
	register int cc;
	int i;

	icp = (struct icmphdr *)outpack;
	icp->icmp_type = ICMP_ECHO;
	icp->icmp_code = 0;
	icp->icmp_cksum = 0;
	icp->icmp_seq = ntransmitted++;
	icp->icmp_id = ident;			/* ID */

	CLR(icp->icmp_seq % mx_dup_ck);

	if (timing)
		(void)gettimeofday((struct timeval *)&outpack[8],
		    (struct timezone *)NULL);

	cc = datalen + 8;			/* skips ICMP portion */

	/* 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("ping: sendto");
		(void)printf("ping: wrote %s %d chars, ret=%d\n",
		    hostname, cc, i);
	}
	if (!(options & F_QUIET) && options & F_FLOOD)
		(void)write(STDOUT_FILENO, &DOT, 1);
}

/*
 * pr_pack --
 *	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!).
 */
void
pr_pack(char *buf, int cc, struct sockaddr_in *from)
{
	register struct icmphdr *icp;
	register int i;
	register u_char *cp,*dp;
/*#if 0*/
	register u_long l;
	register int j;
	static int old_rrlen;
	static char old_rr[MAX_IPOPTLEN];
/*#endif*/
	struct iphdr *ip;
	struct timeval tv, *tp;
	long triptime = 0;
	int hlen, dupflag;

	(void)gettimeofday(&tv, (struct timezone *)NULL);

	/* Check the IP header */
	ip = (struct iphdr *)buf;
	hlen = ip->ip_hl << 2;
	if (cc < datalen + ICMP_MINLEN) {
		if (options & F_VERBOSE)
			(void)fprintf(stderr,
			  "ping: 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 icmphdr *)(buf + hlen);
	if (icp->icmp_type == ICMP_ECHOREPLY) {
		if (icp->icmp_id != ident)
			return;			/* 'Twas not our ECHO */
		++nreceived;
		if (timing) {
#ifndef icmp_data
			tp = (struct timeval *)(icp + 1);
#else
			tp = (struct timeval *)icp->icmp_data;
#endif
			tvsub(&tv, tp);
			triptime = tv.tv_sec * 10000 + (tv.tv_usec / 100);
			tsum += triptime;
			if (triptime < tmin)
				tmin = triptime;
			if (triptime > tmax)
				tmax = triptime;
		}

		if (TST(icp->icmp_seq % mx_dup_ck)) {
			++nrepeats;
			--nreceived;
			dupflag = 1;
		} else {
			SET(icp->icmp_seq % mx_dup_ck);
			dupflag = 0;
		}

		if (options & F_QUIET)
			return;

		if (options & F_FLOOD)
			(void)write(STDOUT_FILENO, &BSPACE, 1);
		else {
			(void)printf("%d bytes from %s: icmp_seq=%u", cc,
			   inet_ntoa(*(struct in_addr *)&from->sin_addr.s_addr),
			   icp->icmp_seq);
			(void)printf(" ttl=%d", ip->ip_ttl);
			if (timing)
				(void)printf(" time=%ld.%ld ms", triptime/10,
						triptime%10);
			if (dupflag)
				(void)printf(" (DUP!)");
			/* check the data */
#ifndef icmp_data
			cp = ((u_char*)(icp + 1) + 8);
#else
			cp = (u_char*)icp->icmp_data + 8;
#endif
			dp = &outpack[8 + sizeof(struct timeval)];
			for (i = 8; i < datalen; ++i, ++cp, ++dp) {
				if (*cp != *dp) {
	(void)printf("\nwrong data byte #%d should be 0x%x but was 0x%x",
	    i, *dp, *cp);
					cp = (u_char*)(icp + 1);
					for (i = 8; i < datalen; ++i, ++cp) {
						if ((i % 32) == 8)
							(void)printf("\n\t");
						(void)printf("%x ", *cp);
					}
					break;
				}
			}
		}
	} else {
		/* We've got something other than an ECHOREPLY */
		if (!(options & F_VERBOSE))
			return;
		(void)printf("%d bytes from %s: ", cc,
		    pr_addr(from->sin_addr.s_addr));
		pr_icmph(icp);
	}

/*#if 0*/
	/* Display any IP options */
	cp = (u_char *)buf + sizeof(struct iphdr);

	for (; hlen > (int)sizeof(struct iphdr); --hlen, ++cp)
		switch (*cp) {
		case IPOPT_EOL:
			hlen = 0;
			break;
		case IPOPT_LSRR:
			(void)printf("\nLSRR: ");
			hlen -= 2;
			j = *++cp;
			++cp;
			if (j > IPOPT_MINOFF)
				for (;;) {
					l = *++cp;
					l = (l<<8) + *++cp;
					l = (l<<8) + *++cp;
					l = (l<<8) + *++cp;
					if (l == 0)
						(void)printf("\t0.0.0.0");
				else
					(void)printf("\t%s", pr_addr(ntohl(l)));
				hlen -= 4;
				j -= 4;
				if (j <= IPOPT_MINOFF)
					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 (i == old_rrlen
			    && cp == (u_char *)buf + sizeof(struct iphdr) + 2
			    && !memcmp((char *)cp, old_rr, i)
			    && !(options & F_FLOOD)) {
				(void)printf("\t(same route)");
				i = ((i + 3) / 4) * 4;
				hlen -= i;
				cp += i;
				break;
			}
			old_rrlen = i;
			memcpy(old_rr, cp, i);
			(void)printf("\nRR: ");
			for (;;) {
				l = *++cp;
				l = (l<<8) + *++cp;
				l = (l<<8) + *++cp;
				l = (l<<8) + *++cp;
				if (l == 0)
					(void)printf("\t0.0.0.0");
				else
					(void)printf("\t%s", pr_addr(ntohl(l)));
				hlen -= 4;
				i -= 4;
				if (i <= 0)
					break;
				(void)putchar('\n');
			}
			break;
		case IPOPT_NOP: