3 "@(#)$Header: /home/ncvs/src/usr.sbin/traceroute/traceroute.c,v 1.10 1996/08/21 05:59:19 peter Exp $ (LBL)";
7 * traceroute host - trace the route ip packets follow going to "host".
9 * Attempt to trace the route an ip packet would follow to some
10 * internet host. We find out intermediate hops by launching probe
11 * packets with a small ttl (time to live) then listening for an
12 * icmp "time exceeded" reply from a gateway. We start our probes
13 * with a ttl of one and increase by one until we get an icmp "port
14 * unreachable" (which means we got to "host") or hit a max (which
15 * defaults to 30 hops & can be changed with the -m flag). Three
16 * probes (change with -q flag) are sent at each ttl setting and a
17 * line is printed showing the ttl, address of the gateway and
18 * round trip time of each probe. If the probe answers come from
19 * different gateways, the address of each responding system will
20 * be printed. If there is no response within a 5 sec. timeout
21 * interval (changed with the -w flag), a "*" is printed for that
24 * Probe packets are UDP format. We don't want the destination
25 * host to process them so the destination port is set to an
26 * unlikely value (if some clod on the destination is using that
27 * value, it can be changed with the -p flag).
29 * A sample use might be:
31 * [yak 71]% traceroute nis.nsf.net.
32 * traceroute to nis.nsf.net (35.1.1.48), 30 hops max, 56 byte packet
33 * 1 helios.ee.lbl.gov (128.3.112.1) 19 ms 19 ms 0 ms
34 * 2 lilac-dmc.Berkeley.EDU (128.32.216.1) 39 ms 39 ms 19 ms
35 * 3 lilac-dmc.Berkeley.EDU (128.32.216.1) 39 ms 39 ms 19 ms
36 * 4 ccngw-ner-cc.Berkeley.EDU (128.32.136.23) 39 ms 40 ms 39 ms
37 * 5 ccn-nerif22.Berkeley.EDU (128.32.168.22) 39 ms 39 ms 39 ms
38 * 6 128.32.197.4 (128.32.197.4) 40 ms 59 ms 59 ms
39 * 7 131.119.2.5 (131.119.2.5) 59 ms 59 ms 59 ms
40 * 8 129.140.70.13 (129.140.70.13) 99 ms 99 ms 80 ms
41 * 9 129.140.71.6 (129.140.71.6) 139 ms 239 ms 319 ms
42 * 10 129.140.81.7 (129.140.81.7) 220 ms 199 ms 199 ms
43 * 11 nic.merit.edu (35.1.1.48) 239 ms 239 ms 239 ms
45 * Note that lines 2 & 3 are the same. This is due to a buggy
46 * kernel on the 2nd hop system -- lbl-csam.arpa -- that forwards
47 * packets with a zero ttl.
49 * A more interesting example is:
51 * [yak 72]% traceroute allspice.lcs.mit.edu.
52 * traceroute to allspice.lcs.mit.edu (18.26.0.115), 30 hops max
53 * 1 helios.ee.lbl.gov (128.3.112.1) 0 ms 0 ms 0 ms
54 * 2 lilac-dmc.Berkeley.EDU (128.32.216.1) 19 ms 19 ms 19 ms
55 * 3 lilac-dmc.Berkeley.EDU (128.32.216.1) 39 ms 19 ms 19 ms
56 * 4 ccngw-ner-cc.Berkeley.EDU (128.32.136.23) 19 ms 39 ms 39 ms
57 * 5 ccn-nerif22.Berkeley.EDU (128.32.168.22) 20 ms 39 ms 39 ms
58 * 6 128.32.197.4 (128.32.197.4) 59 ms 119 ms 39 ms
59 * 7 131.119.2.5 (131.119.2.5) 59 ms 59 ms 39 ms
60 * 8 129.140.70.13 (129.140.70.13) 80 ms 79 ms 99 ms
61 * 9 129.140.71.6 (129.140.71.6) 139 ms 139 ms 159 ms
62 * 10 129.140.81.7 (129.140.81.7) 199 ms 180 ms 300 ms
63 * 11 129.140.72.17 (129.140.72.17) 300 ms 239 ms 239 ms
65 * 13 128.121.54.72 (128.121.54.72) 259 ms 499 ms 279 ms
70 * 18 ALLSPICE.LCS.MIT.EDU (18.26.0.115) 339 ms 279 ms 279 ms
72 * (I start to see why I'm having so much trouble with mail to
73 * MIT.) Note that the gateways 12, 14, 15, 16 & 17 hops away
74 * either don't send ICMP "time exceeded" messages or send them
75 * with a ttl too small to reach us. 14 - 17 are running the
76 * MIT C Gateway code that doesn't send "time exceeded"s. God
77 * only knows what's going on with 12.
79 * The silent gateway 12 in the above may be the result of a bug in
80 * the 4.[23]BSD network code (and its derivatives): 4.x (x <= 3)
81 * sends an unreachable message using whatever ttl remains in the
82 * original datagram. Since, for gateways, the remaining ttl is
83 * zero, the icmp "time exceeded" is guaranteed to not make it back
84 * to us. The behavior of this bug is slightly more interesting
85 * when it appears on the destination system:
87 * 1 helios.ee.lbl.gov (128.3.112.1) 0 ms 0 ms 0 ms
88 * 2 lilac-dmc.Berkeley.EDU (128.32.216.1) 39 ms 19 ms 39 ms
89 * 3 lilac-dmc.Berkeley.EDU (128.32.216.1) 19 ms 39 ms 19 ms
90 * 4 ccngw-ner-cc.Berkeley.EDU (128.32.136.23) 39 ms 40 ms 19 ms
91 * 5 ccn-nerif35.Berkeley.EDU (128.32.168.35) 39 ms 39 ms 39 ms
92 * 6 csgw.Berkeley.EDU (128.32.133.254) 39 ms 59 ms 39 ms
99 * 13 rip.Berkeley.EDU (128.32.131.22) 59 ms ! 39 ms ! 39 ms !
101 * Notice that there are 12 "gateways" (13 is the final
102 * destination) and exactly the last half of them are "missing".
103 * What's really happening is that rip (a Sun-3 running Sun OS3.5)
104 * is using the ttl from our arriving datagram as the ttl in its
105 * icmp reply. So, the reply will time out on the return path
106 * (with no notice sent to anyone since icmp's aren't sent for
107 * icmp's) until we probe with a ttl that's at least twice the path
108 * length. I.e., rip is really only 7 hops away. A reply that
109 * returns with a ttl of 1 is a clue this problem exists.
110 * Traceroute prints a "!" after the time if the ttl is <= 1.
111 * Since vendors ship a lot of obsolete (DEC's Ultrix, Sun 3.x) or
112 * non-standard (HPUX) software, expect to see this problem
113 * frequently and/or take care picking the target host of your
116 * Other possible annotations after the time are !H, !N, !P (got a host,
117 * network or protocol unreachable, respectively), !S or !F (source
118 * route failed or fragmentation needed -- neither of these should
119 * ever occur and the associated gateway is busted if you see one). If
120 * almost all the probes result in some kind of unreachable, traceroute
121 * will give up and exit.
125 * This program must be run by root or be setuid. (I suggest that
126 * you *don't* make it setuid -- casual use could result in a lot
127 * of unnecessary traffic on our poor, congested nets.)
129 * This program requires a kernel mod that does not appear in any
130 * system available from Berkeley: A raw ip socket using proto
131 * IPPROTO_RAW must interpret the data sent as an ip datagram (as
132 * opposed to data to be wrapped in a ip datagram). See the README
133 * file that came with the source to this program for a description
134 * of the mods I made to /sys/netinet/raw_ip.c. Your mileage may
135 * vary. But, again, ANY 4.x (x < 4) BSD KERNEL WILL HAVE TO BE
136 * MODIFIED TO RUN THIS PROGRAM.
138 * The udp port usage may appear bizarre (well, ok, it is bizarre).
139 * The problem is that an icmp message only contains 8 bytes of
140 * data from the original datagram. 8 bytes is the size of a udp
141 * header so, if we want to associate replies with the original
142 * datagram, the necessary information must be encoded into the
143 * udp header (the ip id could be used but there's no way to
144 * interlock with the kernel's assignment of ip id's and, anyway,
145 * it would have taken a lot more kernel hacking to allow this
146 * code to set the ip id). So, to allow two or more users to
147 * use traceroute simultaneously, we use this task's pid as the
148 * source port (the high bit is set to move the port number out
149 * of the "likely" range). To keep track of which probe is being
150 * replied to (so times and/or hop counts don't get confused by a
151 * reply that was delayed in transit), we increment the destination
152 * port number before each probe.
154 * Don't use this as a coding example. I was trying to find a
155 * routing problem and this code sort-of popped out after 48 hours
156 * without sleep. I was amazed it ever compiled, much less ran.
158 * I stole the idea for this program from Steve Deering. Since
159 * the first release, I've learned that had I attended the right
160 * IETF working group meetings, I also could have stolen it from Guy
161 * Almes or Matt Mathis. I don't know (or care) who came up with
162 * the idea first. I envy the originators' perspicacity and I'm
163 * glad they didn't keep the idea a secret.
165 * Tim Seaver, Ken Adelman and C. Philip Wood provided bug fixes and/or
166 * enhancements to the original distribution.
168 * I've hacked up a round-trip-route version of this that works by
169 * sending a loose-source-routed udp datagram through the destination
170 * back to yourself. Unfortunately, SO many gateways botch source
171 * routing, the thing is almost worthless. Maybe one day...
173 * -- Van Jacobson (van@ee.lbl.gov)
174 * Tue Dec 20 03:50:13 PST 1988
177 #include <sys/param.h>
178 #include <sys/file.h>
179 #include <sys/ioctl.h>
180 #include <sys/socket.h>
181 #include <sys/time.h>
183 #include <netinet/in_systm.h>
184 #include <netinet/in.h>
185 #include <netinet/ip.h>
186 #include <netinet/ip_var.h>
187 #include <netinet/ip_icmp.h>
188 #include <netinet/udp.h>
190 #include <arpa/inet.h>
201 #ifdef HAVE_OS_PROTO_H
202 #include "os-proto.h"
205 #define MAXPACKET 65535 /* max ip packet size */
207 #ifndef MAXHOSTNAMELEN
208 #define MAXHOSTNAMELEN 64
211 #if !defined(HAVE_BZERO) && !defined(bzero)
212 #define bzero(s, n) memset(s, 0, n)
213 #define bcopy(s, d, n) memcpy(d, s, n)
216 #if !defined(HAVE_SETLINEBUF) && !defined(setlinebuf)
217 #define setlinebuf(f) setvbuf(f, NULL, _IOLBF, 0)
220 #define Fprintf (void)fprintf
221 #define Sprintf (void)sprintf
222 #define Printf (void)printf
225 * format of a (udp) probe packet.
230 u_char seq; /* sequence number of this packet */
231 u_char ttl; /* ttl packet left with */
232 struct timeval tv; /* time packet left */
235 u_char packet[512]; /* last inbound (icmp) packet */
236 struct opacket *outpacket; /* last output (udp) packet */
238 int s; /* receive (icmp) socket file descriptor */
239 int sndsock; /* send (udp) socket file descriptor */
241 struct sockaddr whereto; /* Who to try to reach */
242 int datalen; /* How much data */
246 char hnamebuf[MAXHOSTNAMELEN];
251 u_short port = 32768+666; /* start udp dest port # for probe packets */
253 int options; /* socket options */
255 int waittime = 5; /* time to wait for response (in seconds) */
256 int nflag; /* print addresses numerically */
259 "Usage: traceroute [-dnrv] [-w wait] [-m max_ttl] [-p port#] [-q nqueries] [-t tos] [-s src_addr] [-g gateway] host [data size]\n";
262 double deltaT(struct timeval *, struct timeval *);
263 int main(int, char **);
264 int wait_for_reply(int, struct sockaddr_in *, struct timeval *);
265 void send_probe(int, int, struct timeval *);
266 char *pr_type(u_char);
267 int packet_ok(u_char *, int, struct sockaddr_in *, int);
268 void print(u_char *, int, struct sockaddr_in *);
269 void tvsub(struct timeval *, struct timeval *);
270 char *inetname(struct in_addr);
273 deltaT(struct timeval *t1p, struct timeval *t2p)
277 dt = (double)(t2p->tv_sec - t1p->tv_sec) * 1000.0 +
278 (double)(t2p->tv_usec - t1p->tv_usec) / 1000.0;
283 main(int argc, char **argv)
285 struct sockaddr_in from;
287 struct sockaddr_in *to = (struct sockaddr_in *) &whereto;
296 u_char optlist[MAX_IPOPTLEN], *oix;
300 * Do the setuid-required stuff first, then lose priveleges ASAP.
301 * Do error checking for these two calls where they appeared in
304 pe = getprotobyname("icmp");
306 if ((s = socket(AF_INET, SOCK_RAW, pe->p_proto)) < 0)
308 else if ((sndsock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0)
315 bzero(optlist, sizeof(optlist));
318 while (argc && *av[0] == '-') {
326 if ((lsrr+1) >= ((MAX_IPOPTLEN-IPOPT_MINOFF)/sizeof(u_long))) {
327 Fprintf(stderr,"No more than %d gateways\n",
328 (u_int)((MAX_IPOPTLEN-IPOPT_MINOFF)/sizeof(u_long))-1);
333 oix++; /* Fill in total length later */
334 *oix++ = IPOPT_MINOFF; /* Pointer to LSRR addresses */
337 if (isdigit(*av[0])) {
340 bcopy(&gw, oix, sizeof(u_long));
342 Fprintf(stderr, "Unknown host %s\n",av[0]);
346 hp = gethostbyname(av[0]);
348 bcopy(hp->h_addr, oix, sizeof(u_long));
350 Fprintf(stderr, "Unknown host %s\n",av[0]);
354 oix += sizeof(u_long);
358 max_ttl = atoi(av[0]);
360 Fprintf(stderr, "max ttl must be >1\n");
371 Fprintf(stderr, "port must be >0\n");
377 nprobes = atoi(av[0]);
379 Fprintf(stderr, "nprobes must be >0\n");
384 options |= SO_DONTROUTE;
388 * set the ip source address of the outbound
389 * probe (e.g., on a multi-homed host).
397 if (tos < 0 || tos > 255) {
398 Fprintf(stderr, "tos must be 0 to 255\n");
407 waittime = atoi(av[0]);
409 Fprintf(stderr, "wait must be >1 sec\n");
426 bzero((char *)&whereto, sizeof(struct sockaddr));
427 to->sin_family = AF_INET;
428 to->sin_addr.s_addr = inet_addr(av[0]);
429 if (to->sin_addr.s_addr != -1) {
430 (void) strncpy(hnamebuf, av[0], sizeof(hnamebuf));
433 hp = gethostbyname(av[0]);
435 to->sin_family = hp->h_addrtype;
436 bcopy(hp->h_addr, (caddr_t)&to->sin_addr, hp->h_length);
437 hostname = strdup(hp->h_name);
439 Printf("%s: unknown host %s\n", argv[0], av[0]);
445 datalen = atoi(av[1]);
446 if (datalen < 0 || datalen >= MAXPACKET - sizeof(struct opacket)) {
447 Fprintf(stderr, "traceroute: packet size must be 0 <= s < %d\n",
448 (u_int)(MAXPACKET - sizeof(struct opacket)));
451 datalen += sizeof(struct opacket);
452 outpacket = (struct opacket *)malloc((unsigned)datalen);
454 perror("traceroute: malloc");
457 bzero((char *)outpacket, datalen);
458 outpacket->ip.ip_dst = to->sin_addr;
459 outpacket->ip.ip_tos = tos;
460 outpacket->ip.ip_v = IPVERSION;
461 outpacket->ip.ip_hl = sizeof(struct ip) >> 2;
463 ident = (getpid() & 0xffff) | 0x8000;
466 Fprintf(stderr, "icmp: unknown protocol\n");
471 perror("traceroute: icmp socket");
474 if (options & SO_DEBUG)
475 (void) setsockopt(s, SOL_SOCKET, SO_DEBUG,
476 (char *)&on, sizeof(on));
477 if (options & SO_DONTROUTE)
478 (void) setsockopt(s, SOL_SOCKET, SO_DONTROUTE,
479 (char *)&on, sizeof(on));
483 perror("traceroute: raw socket");
489 optlist[IPOPT_OLEN]=IPOPT_MINOFF-1+(lsrr*sizeof(u_long));
490 bcopy((caddr_t)&to->sin_addr, oix, sizeof(u_long));
491 oix += sizeof(u_long);
492 while ((oix - optlist)&3) oix++; /* Pad to an even boundry */
494 if ((pe = getprotobyname("ip")) == NULL) {
495 perror("traceroute: unknown protocol ip\n");
499 if ((setsockopt(sndsock, pe->p_proto, IP_OPTIONS, optlist, oix-optlist)) < 0) {
500 perror("traceroute: lsrr options");
507 if (setsockopt(sndsock, SOL_SOCKET, SO_SNDBUF, (char *)&datalen,
508 sizeof(datalen)) < 0) {
509 perror("traceroute: SO_SNDBUF");
514 if (setsockopt(sndsock, IPPROTO_IP, IP_HDRINCL, (char *)&on,
516 perror("traceroute: IP_HDRINCL");
520 if (options & SO_DEBUG)
521 (void) setsockopt(sndsock, SOL_SOCKET, SO_DEBUG,
522 (char *)&on, sizeof(on));
523 if (options & SO_DONTROUTE)
524 (void) setsockopt(sndsock, SOL_SOCKET, SO_DONTROUTE,
525 (char *)&on, sizeof(on));
528 bzero((char *)&from, sizeof(struct sockaddr));
529 from.sin_family = AF_INET;
530 from.sin_addr.s_addr = inet_addr(source);
531 if (from.sin_addr.s_addr == -1) {
532 Printf("traceroute: unknown host %s\n", source);
535 outpacket->ip.ip_src = from.sin_addr;
537 if (bind(sndsock, (struct sockaddr *)&from, sizeof(from)) < 0) {
538 perror ("traceroute: bind:");
544 Fprintf(stderr, "traceroute to %s (%s)", hostname,
545 inet_ntoa(to->sin_addr));
547 Fprintf(stderr, " from %s", source);
548 Fprintf(stderr, ", %d hops max, %d byte packets\n", max_ttl, datalen);
549 (void) fflush(stderr);
551 for (ttl = 1; ttl <= max_ttl; ++ttl) {
557 for (probe = 0; probe < nprobes; ++probe) {
559 struct timeval t1, t2;
563 (void) gettimeofday(&t1, &tz);
564 send_probe(++seq, ttl, &t1);
565 while ((cc = wait_for_reply(s, &from, &t1)) != 0) {
566 (void) gettimeofday(&t2, &tz);
567 if ((i = packet_ok(packet, cc, &from, seq))) {
570 if (from.sin_addr.s_addr != lastaddr) {
571 print(packet, cc, &from);
572 lastaddr = from.sin_addr.s_addr;
574 T = deltaT(&t1, &t2);
575 #ifdef SANE_PRECISION
585 Printf(" %.*f ms", precis, T);
587 case ICMP_UNREACH_PORT:
589 ip = (struct ip *)packet;
595 case ICMP_UNREACH_NET:
599 case ICMP_UNREACH_HOST:
603 case ICMP_UNREACH_PROTOCOL:
607 case ICMP_UNREACH_NEEDFRAG:
611 case ICMP_UNREACH_SRCFAIL:
615 case ICMP_UNREACH_NET_PROHIB:
619 case ICMP_UNREACH_HOST_PROHIB:
623 case ICMP_UNREACH_FILTER_PROHIB:
627 default: /* unknown */
628 Printf(" !<%d>", i - 1);
630 case -2: /* normal reply */
638 (void) fflush(stdout);
641 if (got_there || unreachable >= nprobes-1)
648 wait_for_reply(int sock, struct sockaddr_in *from, struct timeval *sent)
651 struct timeval now, wait;
653 int fromlen = sizeof (*from);
657 gettimeofday(&now, NULL);
658 wait.tv_sec = (sent->tv_sec + waittime) - now.tv_sec;
659 wait.tv_usec = sent->tv_usec - now.tv_usec;
660 if (wait.tv_usec < 0) {
661 wait.tv_usec += 1000000;
665 wait.tv_sec = wait.tv_usec = 0;
667 if (select(sock+1, &fds, (fd_set *)0, (fd_set *)0, &wait) > 0)
668 cc=recvfrom(s, (char *)packet, sizeof(packet), 0,
669 (struct sockaddr *)from, &fromlen);
676 send_probe(int seq, int ttl, struct timeval *tp)
678 struct opacket *op = outpacket;
679 struct ip *ip = &op->ip;
680 struct udphdr *up = &op->udp;
684 ip->ip_p = IPPROTO_UDP;
685 ip->ip_len = datalen;
688 up->uh_sport = htons(ident);
689 up->uh_dport = htons(port+seq);
690 up->uh_ulen = htons((u_short)(datalen - sizeof(struct ip)));
697 i = sendto(sndsock, (char *)outpacket, datalen, 0, &whereto,
698 sizeof(struct sockaddr));
699 if (i < 0 || i != datalen) {
702 Printf("traceroute: wrote %s %d chars, ret=%d\n", hostname,
704 (void) fflush(stdout);
709 * Convert an ICMP "type" field to a printable string.
714 static char *ttab[] = {
715 "Echo Reply", "ICMP 1", "ICMP 2", "Dest Unreachable",
716 "Source Quench", "Redirect", "ICMP 6", "ICMP 7",
717 "Echo", "ICMP 9", "ICMP 10", "Time Exceeded",
718 "Param Problem", "Timestamp", "Timestamp Reply", "Info Request",
723 return("OUT-OF-RANGE");
730 packet_ok(u_char *buf, int cc, struct sockaddr_in *from, int seq)
732 register struct icmp *icp;
738 ip = (struct ip *) buf;
739 hlen = ip->ip_hl << 2;
740 if (cc < hlen + ICMP_MINLEN) {
742 Printf("packet too short (%d bytes) from %s\n", cc,
743 inet_ntoa(from->sin_addr));
747 icp = (struct icmp *)(buf + hlen);
749 icp = (struct icmp *)buf;
751 type = icp->icmp_type; code = icp->icmp_code;
752 if ((type == ICMP_TIMXCEED && code == ICMP_TIMXCEED_INTRANS) ||
753 type == ICMP_UNREACH) {
758 hlen = hip->ip_hl << 2;
759 up = (struct udphdr *)((u_char *)hip + hlen);
760 if (hlen + 12 <= cc && hip->ip_p == IPPROTO_UDP &&
761 up->uh_sport == htons(ident) &&
762 up->uh_dport == htons(port+seq))
763 return (type == ICMP_TIMXCEED? -1 : code+1);
768 u_long *lp = (u_long *)&icp->icmp_ip;
770 Printf("\n%d bytes from %s", cc, inet_ntoa(from->sin_addr));
771 Printf(" to %s", inet_ntoa(ip->ip_dst));
772 Printf(": icmp type %d (%s) code %d\n", type, pr_type(type),
774 for (i = 4; i < cc ; i += sizeof(long))
775 Printf("%2d: x%8.8lx\n", i, *lp++);
783 print(u_char *buf, int cc, struct sockaddr_in *from)
788 ip = (struct ip *) buf;
789 hlen = ip->ip_hl << 2;
793 Printf(" %s", inet_ntoa(from->sin_addr));
795 Printf(" %s (%s)", inetname(from->sin_addr),
796 inet_ntoa(from->sin_addr));
799 Printf (" %d bytes to %s", cc, inet_ntoa (ip->ip_dst));
805 * Checksum routine for Internet Protocol family headers (C Version)
807 in_cksum(u_short *addr, int len)
809 register int nleft = len;
810 register u_short *w = addr;
811 register u_short answer;
812 register int sum = 0;
815 * Our algorithm is simple, using a 32 bit accumulator (sum),
816 * we add sequential 16 bit words to it, and at the end, fold
817 * back all the carry bits from the top 16 bits into the lower
825 /* mop up an odd byte, if necessary */
830 * add back carry outs from top 16 bits to low 16 bits
832 sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
833 sum += (sum >> 16); /* add carry */
834 answer = ~sum; /* truncate to 16 bits */
840 * Subtract 2 timeval structs: out = out - in.
841 * Out is assumed to be >= in.
844 tvsub(register struct timeval *out, register struct timeval *in)
846 if ((out->tv_usec -= in->tv_usec) < 0) {
848 out->tv_usec += 1000000;
850 out->tv_sec -= in->tv_sec;
855 * Construct an Internet address representation.
856 * If the nflag has been supplied, give
857 * numeric value, otherwise try for symbolic name.
860 inetname(struct in_addr in)
863 static char line[50];
865 static char domain[MAXHOSTNAMELEN + 1];
866 static int first = 1;
868 if (first && !nflag) {
870 if (gethostname(domain, sizeof(domain)) == 0 &&
871 (cp = strchr(domain, '.')))
872 (void) strncpy(domain, cp + 1, sizeof(domain));
877 if (!nflag && in.s_addr != INADDR_ANY) {
878 hp = gethostbyaddr((char *)&in, sizeof (in), AF_INET);
880 if ((cp = strchr(hp->h_name, '.')) &&
881 !strcmp(cp + 1, domain))
887 (void) strncpy(line, cp, sizeof(line));
889 in.s_addr = ntohl(in.s_addr);
890 #define C(x) ((x) & 0xff)
891 Sprintf(line, "%lu.%lu.%lu.%lu", C(in.s_addr >> 24),
892 C(in.s_addr >> 16), C(in.s_addr >> 8), C(in.s_addr));