ping.c

一个在UCLINUX环境下实现的PING程序

/*
 * Copyright (c) 1989 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Muuss.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

char copyright[] =
  "@(#) Copyright (c) 1989 The Regents of the University of California.\n"
  "All rights reserved.\n";
/*
 * From: @(#)ping.c	5.9 (Berkeley) 5/12/91
 */
char rcsid[] = "$Original-Id: ping.c,v 1.22 1997/06/08 19:39:47 dholland Exp $";
char pkg[] = "netkit-base-0.10";

/*
 *			P I N G . C
 *
 * Using the InterNet Control Message Protocol (ICMP) "ECHO" facility,
 * measure round-trip-delays and packet loss across network paths.
 *
 * Author -
 *	Mike Muuss
 *	U. S. Army Ballistic Research Laboratory
 *	December, 1983
 *
 * Status -
 *	Public Domain.  Distribution Unlimited.
 * Bugs -
 *	More statistics could always be gathered.
 *	This program has to run SUID to ROOT to access the ICMP socket.
 */

#include <sys/param.h>
#include <sys/socket.h>
#include <sys/file.h>
#include <sys/time.h>
#include <sys/signal.h>

#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#include <errno.h>
#include <getopt.h>

#include "resolv.h"
#include "stamp.h"

/*
 * Note: on some systems dropping root makes the process dumpable or
 * traceable. In that case if you enable dropping root and someone
 * traces ping, they get control of a raw socket and can start
 * spoofing whatever packets they like. SO BE CAREFUL.
 */
#ifdef __linux__
#define SAFE_TO_DROP_ROOT
#endif

#if defined(__GLIBC__) && (__GLIBC__ >= 2)
#define icmphdr			icmp
#define ICMP_DEST_UNREACH	ICMP_UNREACH
#define ICMP_NET_UNREACH	ICMP_UNREACH_NET
#define ICMP_HOST_UNREACH	ICMP_UNREACH_HOST
#define ICMP_PORT_UNREACH	ICMP_UNREACH_PORT
#define ICMP_PROT_UNREACH	ICMP_UNREACH_PROTOCOL
#define ICMP_FRAG_NEEDED	ICMP_UNREACH_NEEDFRAG
#define ICMP_SR_FAILED		ICMP_UNREACH_SRCFAIL
#define ICMP_NET_UNKNOWN	ICMP_UNREACH_NET_UNKNOWN
#define ICMP_HOST_UNKNOWN	ICMP_UNREACH_HOST_UNKNOWN
#define ICMP_HOST_ISOLATED	ICMP_UNREACH_ISOLATED
#define ICMP_NET_UNR_TOS	ICMP_UNREACH_TOSNET
#define ICMP_HOST_UNR_TOS	ICMP_UNREACH_TOSHOST
#define ICMP_SOURCE_QUENCH	ICMP_SOURCEQUENCH
#define ICMP_REDIR_NET		ICMP_REDIRECT_NET
#define ICMP_REDIR_HOST		ICMP_REDIRECT_HOST
#define ICMP_REDIR_NETTOS	ICMP_REDIRECT_TOSNET
#define ICMP_REDIR_HOSTTOS	ICMP_REDIRECT_TOSHOST
#define ICMP_TIME_EXCEEDED	ICMP_TIMXCEED
#define ICMP_EXC_TTL		ICMP_TIMXCEED_INTRANS
#define ICMP_EXC_FRAGTIME	ICMP_TIMXCEED_REASS
#define	ICMP_PARAMETERPROB	ICMP_PARAMPROB
#define ICMP_TIMESTAMP		ICMP_TSTAMP
#define ICMP_TIMESTAMPREPLY	ICMP_TSTAMPREPLY
#define ICMP_INFO_REQUEST	ICMP_IREQ
#define ICMP_INFO_REPLY		ICMP_IREQREPLY
#else
#define ICMP_MINLEN	28
#define inet_ntoa(x) inet_ntoa(*((struct in_addr *)&(x)))
#endif


#define	DEFDATALEN	(64 - 8)	/* default data length */
#define	MAXIPLEN	60
#define	MAXICMPLEN	76
#define	MAXPACKET	(2048 - 60 - 8)/* max packet size */
#define	MAXWAIT		10		/* max seconds to wait for response */
#define	NROUTES		9		/* number of record route slots */

#define	A(bit)		rcvd_tbl[(bit)>>3]	/* identify byte in array */
#define	B(bit)		(1 << ((bit) & 0x07))	/* identify bit in byte */
#define	SET(bit)	(A(bit) |= B(bit))
#define	CLR(bit)	(A(bit) &= (~B(bit)))
#define	TST(bit)	(A(bit) & B(bit))

/* various options */
int options;
#define	F_FLOOD		0x001
#define	F_INTERVAL	0x002
#define	F_NUMERIC	0x004
#define	F_PINGFILLED	0x008
#define	F_QUIET		0x010
#define	F_RROUTE	0x020
#define	F_SO_DEBUG	0x040
#define	F_SO_DONTROUTE	0x080
#define	F_VERBOSE	0x100

/* multicast options */
int moptions;
#define MULTICAST_NOLOOP	0x001
#define MULTICAST_TTL		0x002
#define MULTICAST_IF		0x004

/*
 * MAX_DUP_CHK is the number of bits in received table, i.e. the maximum
 * number of received sequence numbers we can keep track of.  Change 128
 * to 8192 for complete accuracy...
 */
#define	MAX_DUP_CHK	(8 * 128)
int mx_dup_ck = MAX_DUP_CHK;
char rcvd_tbl[MAX_DUP_CHK / 8];

struct sockaddr whereto;	/* who to ping */
int datalen = DEFDATALEN;
int s;				/* socket file descriptor */
u_char outpack[MAXPACKET];
char BSPACE = '\b';		/* characters written for flood */
char DOT = '.';
static char *hostname;
static int ident;		/* process id to identify our packets */

/* counters */
static long npackets;		/* max packets to transmit */
static long nreceived;		/* # of packets we got back */
static long nrepeats;		/* number of duplicates */
static long ntransmitted;	/* sequence # for outbound packets = #sent */
static int interval = 1;	/* interval between packets */

/* timing */
static int timing;		/* flag to do timing */
static long tmin = LONG_MAX;	/* minimum round trip time */
static long tmax = 0;		/* maximum round trip time */
static u_long tsum;		/* sum of all times, for doing average */

/* protos */
static char *pr_addr(u_long);
static int in_cksum(u_short *addr, int len);
static void catcher(int);
static void finish(int ignore);
static void pinger(void);
static void fill(void *bp, char *patp);
static void usage(void);
static void pr_pack(char *buf, int cc, struct sockaddr_in *from);
static void tvsub(struct timeval *out, struct timeval *in);
static void pr_icmph(struct icmphdr *icp);
static void pr_retip(struct iphdr *ip);


int
main(int argc, char *argv[])
{
	struct timeval timeout;
	struct hostent *hp;
	struct sockaddr_in *to;
	struct protoent *proto;
	struct in_addr ifaddr;
	int i;
	int ch, fdmask, hold, packlen, preload;
	u_char *datap, *packet;
	char *target, hnamebuf[MAXHOSTNAMELEN];
	u_char ttl, loop;
	int am_i_root;
#ifdef IP_OPTIONS
	char rspace[3 + 4 * NROUTES + 1];	/* record route space */
#endif

	static char *null = NULL;

        check_version_argument;
        
	/*__environ = &null;*/
	am_i_root = (getuid()==0);

	/*
	 * Pull this stuff up front so we can drop root if desired.
	 */
	if ((s = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0) {
		if (errno==EPERM) {
			fprintf(stderr, "ping: ping must run as root\n");
		}
		else perror("ping: socket");
		exit(2);
	}

#ifdef SAFE_TO_DROP_ROOT
	setuid(getuid());
#endif

	preload = 0;
	datap = &outpack[8 + sizeof(struct timeval)];
	while ((ch = getopt(argc, argv, "I:LRc:dfh:i:l:np:qrs:t:v")) != EOF)
		switch(ch) {
		case 'c':
			npackets = atoi(optarg);
			if (npackets <= 0) {
				(void)fprintf(stderr,
				    "ping: bad number of packets to transmit.\n");
				exit(2);
			}
			break;
		case 'd':
			options |= F_SO_DEBUG;
			break;
		case 'f':
			if (!am_i_root) {
				(void)fprintf(stderr,
				    "ping: %s\n", strerror(EPERM));
				exit(2);
			}
			options |= F_FLOOD;
			setbuf(stdout, NULL);
			break;
		case 'i':		/* wait between sending packets */
			interval = atoi(optarg);
			if (interval <= 0) {
				(void)fprintf(stderr,
				    "ping: bad timing interval.\n");
				exit(2);
			}
			options |= F_INTERVAL;
			break;
		case 'l':
			if (!am_i_root) {
				(void)fprintf(stderr,
				    "ping: %s\n", strerror(EPERM));
				exit(2);
			}
			preload = atoi(optarg);
			if (preload < 0) {
				(void)fprintf(stderr,
				    "ping: bad preload value.\n");
				exit(2);
			}
			break;
		case 'n':
			options |= F_NUMERIC;
			break;
		case 'p':		/* fill buffer with user pattern */
			options |= F_PINGFILLED;
			fill(datap, optarg);
			break;
		case 'q':
			options |= F_QUIET;
			break;
		case 'R':
			options |= F_RROUTE;
			break;
		case 'r':
			options |= F_SO_DONTROUTE;
			break;
		case 's':		/* size of packet to send */
			datalen = atoi(optarg);
			if (datalen > MAXPACKET) {
				(void)fprintf(stderr,
				    "ping: packet size too large.\n");
				exit(2);
			}
			if (datalen <= 0) {
				(void)fprintf(stderr,
				    "ping: illegal packet size.\n");
				exit(2);
			}
			break;
		case 'v':
			options |= F_VERBOSE;
			break;
		case 'L':
			moptions |= MULTICAST_NOLOOP;
			loop = 0;
			break;
		case 't':
			moptions |= MULTICAST_TTL;
			i = atoi(optarg);
			if (i < 0 || i > 255) {
				printf("ttl %u out of range\n", i);
				exit(2);
			}
			ttl = i;
			break;
		case 'I':
			moptions |= MULTICAST_IF;
			{
				int i1, i2, i3, i4;
				char junk;

				if (sscanf(optarg, "%u.%u.%u.%u%c",
					   &i1, &i2, &i3, &i4, &junk) != 4) {
					printf("bad interface address '%s'\n",
					       optarg);
					exit(2);
				}
				ifaddr.s_addr = (i1<<24)|(i2<<16)|(i3<<8)|i4;
				ifaddr.s_addr = htonl(ifaddr.s_addr);
			}
			break;
		default:
			usage();
		}
	argc -= optind;
	argv += optind;
	
	if (argc != 1)
		usage();
	target = *argv;

	memset(&whereto, 0, sizeof(struct sockaddr));
	to = (struct sockaddr_in *)&whereto;
	to->sin_family = AF_INET;
	if (inet_aton(target, &to->sin_addr)) {
		hostname = target;
	}
	else {
		char * addr = resolve_name(target, 0);
		if (!addr) {
			(void)fprintf(stderr,
			    "ping: unknown host %s\n", target);
			exit(2);
		}
		to->sin_addr.s_addr = inet_addr(addr);
		hostname = target;
		/*
		hp = gethostbyname(target);
		if (!hp) {
			(void)fprintf(stderr,
			    "ping: unknown host %s\n", target);
			exit(2);
		}
		to->sin_family = hp->h_addrtype;
		if (hp->h_length > (int)sizeof(to->sin_addr)) {
			hp->h_length = sizeof(to->sin_addr);
		}
		memcpy(&to->sin_addr, hp->h_addr, hp->h_length);
		(void)strncpy(hnamebuf, hp->h_name, sizeof(hnamebuf) - 1);
		hostname = hnamebuf;
		*/
	}

	if (options & F_FLOOD && options & F_INTERVAL) {
		(void)fprintf(stderr,
		    "ping: -f and -i incompatible options.\n");
		exit(2);
	}

	if (datalen >= (int)sizeof(struct timeval)) /* can we time transfer */
		timing = 1;
	packlen = datalen + MAXIPLEN + MAXICMPLEN;
	packet = malloc((u_int)packlen);
	if (!packet) {
		(void)fprintf(stderr, "ping: out of memory.\n");
		exit(2);
	}
	if (!(options & F_PINGFILLED))
		for (i = 8; i < datalen; ++i)
			*datap++ = i;

	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;
		int 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);