3 "@(#)$Header: traceroute.c,v 1.27 95/10/18 00:17:06 leres 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;
299 bzero(optlist, sizeof(optlist));
302 while (argc && *av[0] == '-') {
310 if ((lsrr+1) >= ((MAX_IPOPTLEN-IPOPT_MINOFF)/sizeof(u_long))) {
311 Fprintf(stderr,"No more than %d gateways\n",
312 (u_int)((MAX_IPOPTLEN-IPOPT_MINOFF)/sizeof(u_long))-1);
317 oix++; /* Fill in total length later */
318 *oix++ = IPOPT_MINOFF; /* Pointer to LSRR addresses */
321 if (isdigit(*av[0])) {
324 bcopy(&gw, oix, sizeof(u_long));
326 Fprintf(stderr, "Unknown host %s\n",av[0]);
330 hp = gethostbyname(av[0]);
332 bcopy(hp->h_addr, oix, sizeof(u_long));
334 Fprintf(stderr, "Unknown host %s\n",av[0]);
338 oix += sizeof(u_long);
342 max_ttl = atoi(av[0]);
344 Fprintf(stderr, "max ttl must be >1\n");
355 Fprintf(stderr, "port must be >0\n");
361 nprobes = atoi(av[0]);
363 Fprintf(stderr, "nprobes must be >0\n");
368 options |= SO_DONTROUTE;
372 * set the ip source address of the outbound
373 * probe (e.g., on a multi-homed host).
381 if (tos < 0 || tos > 255) {
382 Fprintf(stderr, "tos must be 0 to 255\n");
391 waittime = atoi(av[0]);
393 Fprintf(stderr, "wait must be >1 sec\n");
410 bzero((char *)&whereto, sizeof(struct sockaddr));
411 to->sin_family = AF_INET;
412 to->sin_addr.s_addr = inet_addr(av[0]);
413 if (to->sin_addr.s_addr != -1) {
414 (void) strcpy(hnamebuf, av[0]);
417 hp = gethostbyname(av[0]);
419 to->sin_family = hp->h_addrtype;
420 bcopy(hp->h_addr, (caddr_t)&to->sin_addr, hp->h_length);
421 hostname = strdup(hp->h_name);
423 Printf("%s: unknown host %s\n", argv[0], av[0]);
429 datalen = atoi(av[1]);
430 if (datalen < 0 || datalen >= MAXPACKET - sizeof(struct opacket)) {
431 Fprintf(stderr, "traceroute: packet size must be 0 <= s < %d\n",
432 (u_int)(MAXPACKET - sizeof(struct opacket)));
435 datalen += sizeof(struct opacket);
436 outpacket = (struct opacket *)malloc((unsigned)datalen);
438 perror("traceroute: malloc");
441 bzero((char *)outpacket, datalen);
442 outpacket->ip.ip_dst = to->sin_addr;
443 outpacket->ip.ip_tos = tos;
444 outpacket->ip.ip_v = IPVERSION;
445 outpacket->ip.ip_hl = sizeof(struct ip) >> 2;
447 ident = (getpid() & 0xffff) | 0x8000;
449 if ((pe = getprotobyname("icmp")) == NULL) {
450 Fprintf(stderr, "icmp: unknown protocol\n");
453 if ((s = socket(AF_INET, SOCK_RAW, pe->p_proto)) < 0) {
454 perror("traceroute: icmp socket");
457 if (options & SO_DEBUG)
458 (void) setsockopt(s, SOL_SOCKET, SO_DEBUG,
459 (char *)&on, sizeof(on));
460 if (options & SO_DONTROUTE)
461 (void) setsockopt(s, SOL_SOCKET, SO_DONTROUTE,
462 (char *)&on, sizeof(on));
464 if ((sndsock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0) {
465 perror("traceroute: raw socket");
471 optlist[IPOPT_OLEN]=IPOPT_MINOFF-1+(lsrr*sizeof(u_long));
472 bcopy((caddr_t)&to->sin_addr, oix, sizeof(u_long));
473 oix += sizeof(u_long);
474 while ((oix - optlist)&3) oix++; /* Pad to an even boundry */
476 if ((pe = getprotobyname("ip")) == NULL) {
477 perror("traceroute: unknown protocol ip\n");
481 if ((setsockopt(sndsock, pe->p_proto, IP_OPTIONS, optlist, oix-optlist)) < 0) {
482 perror("traceroute: lsrr options");
489 if (setsockopt(sndsock, SOL_SOCKET, SO_SNDBUF, (char *)&datalen,
490 sizeof(datalen)) < 0) {
491 perror("traceroute: SO_SNDBUF");
496 if (setsockopt(sndsock, IPPROTO_IP, IP_HDRINCL, (char *)&on,
498 perror("traceroute: IP_HDRINCL");
502 if (options & SO_DEBUG)
503 (void) setsockopt(sndsock, SOL_SOCKET, SO_DEBUG,
504 (char *)&on, sizeof(on));
505 if (options & SO_DONTROUTE)
506 (void) setsockopt(sndsock, SOL_SOCKET, SO_DONTROUTE,
507 (char *)&on, sizeof(on));
510 bzero((char *)&from, sizeof(struct sockaddr));
511 from.sin_family = AF_INET;
512 from.sin_addr.s_addr = inet_addr(source);
513 if (from.sin_addr.s_addr == -1) {
514 Printf("traceroute: unknown host %s\n", source);
517 outpacket->ip.ip_src = from.sin_addr;
519 if (bind(sndsock, (struct sockaddr *)&from, sizeof(from)) < 0) {
520 perror ("traceroute: bind:");
526 Fprintf(stderr, "traceroute to %s (%s)", hostname,
527 inet_ntoa(to->sin_addr));
529 Fprintf(stderr, " from %s", source);
530 Fprintf(stderr, ", %d hops max, %d byte packets\n", max_ttl, datalen);
531 (void) fflush(stderr);
533 for (ttl = 1; ttl <= max_ttl; ++ttl) {
539 for (probe = 0; probe < nprobes; ++probe) {
541 struct timeval t1, t2;
545 (void) gettimeofday(&t1, &tz);
546 send_probe(++seq, ttl, &t1);
547 while ((cc = wait_for_reply(s, &from, &t1)) != 0) {
548 (void) gettimeofday(&t2, &tz);
549 if ((i = packet_ok(packet, cc, &from, seq))) {
550 if (from.sin_addr.s_addr != lastaddr) {
551 print(packet, cc, &from);
552 lastaddr = from.sin_addr.s_addr;
554 Printf(" %.3f ms", deltaT(&t1, &t2));
556 case ICMP_UNREACH_PORT:
558 ip = (struct ip *)packet;
564 case ICMP_UNREACH_NET:
568 case ICMP_UNREACH_HOST:
572 case ICMP_UNREACH_PROTOCOL:
576 case ICMP_UNREACH_NEEDFRAG:
580 case ICMP_UNREACH_SRCFAIL:
590 (void) fflush(stdout);
593 if (got_there || unreachable >= nprobes-1)
600 wait_for_reply(int sock, struct sockaddr_in *from, struct timeval *sent)
603 struct timeval now, wait;
605 int fromlen = sizeof (*from);
609 gettimeofday(&now, NULL);
610 wait.tv_sec = (sent->tv_sec + waittime) - now.tv_sec;
611 wait.tv_usec = sent->tv_usec - now.tv_usec;
612 if (wait.tv_usec < 0) {
613 wait.tv_usec += 1000000;
617 wait.tv_sec = wait.tv_usec = 0;
619 if (select(sock+1, &fds, (fd_set *)0, (fd_set *)0, &wait) > 0)
620 cc=recvfrom(s, (char *)packet, sizeof(packet), 0,
621 (struct sockaddr *)from, &fromlen);
628 send_probe(int seq, int ttl, struct timeval *tp)
630 struct opacket *op = outpacket;
631 struct ip *ip = &op->ip;
632 struct udphdr *up = &op->udp;
636 ip->ip_p = IPPROTO_UDP;
637 ip->ip_len = datalen;
640 up->uh_sport = htons(ident);
641 up->uh_dport = htons(port+seq);
642 up->uh_ulen = htons((u_short)(datalen - sizeof(struct ip)));
649 i = sendto(sndsock, (char *)outpacket, datalen, 0, &whereto,
650 sizeof(struct sockaddr));
651 if (i < 0 || i != datalen) {
654 Printf("traceroute: wrote %s %d chars, ret=%d\n", hostname,
656 (void) fflush(stdout);
661 * Convert an ICMP "type" field to a printable string.
666 static char *ttab[] = {
667 "Echo Reply", "ICMP 1", "ICMP 2", "Dest Unreachable",
668 "Source Quench", "Redirect", "ICMP 6", "ICMP 7",
669 "Echo", "ICMP 9", "ICMP 10", "Time Exceeded",
670 "Param Problem", "Timestamp", "Timestamp Reply", "Info Request",
675 return("OUT-OF-RANGE");
682 packet_ok(u_char *buf, int cc, struct sockaddr_in *from, int seq)
684 register struct icmp *icp;
690 ip = (struct ip *) buf;
691 hlen = ip->ip_hl << 2;
692 if (cc < hlen + ICMP_MINLEN) {
694 Printf("packet too short (%d bytes) from %s\n", cc,
695 inet_ntoa(from->sin_addr));
699 icp = (struct icmp *)(buf + hlen);
701 icp = (struct icmp *)buf;
703 type = icp->icmp_type; code = icp->icmp_code;
704 if ((type == ICMP_TIMXCEED && code == ICMP_TIMXCEED_INTRANS) ||
705 type == ICMP_UNREACH) {
710 hlen = hip->ip_hl << 2;
711 up = (struct udphdr *)((u_char *)hip + hlen);
712 if (hlen + 12 <= cc && hip->ip_p == IPPROTO_UDP &&
713 up->uh_sport == htons(ident) &&
714 up->uh_dport == htons(port+seq))
715 return (type == ICMP_TIMXCEED? -1 : code+1);
720 u_long *lp = (u_long *)&icp->icmp_ip;
722 Printf("\n%d bytes from %s to %s", cc,
723 inet_ntoa(from->sin_addr), inet_ntoa(ip->ip_dst));
724 Printf(": icmp type %d (%s) code %d\n", type, pr_type(type),
726 for (i = 4; i < cc ; i += sizeof(long))
727 Printf("%2d: x%8.8lx\n", i, *lp++);
735 print(u_char *buf, int cc, struct sockaddr_in *from)
740 ip = (struct ip *) buf;
741 hlen = ip->ip_hl << 2;
745 Printf(" %s", inet_ntoa(from->sin_addr));
747 Printf(" %s (%s)", inetname(from->sin_addr),
748 inet_ntoa(from->sin_addr));
751 Printf (" %d bytes to %s", cc, inet_ntoa (ip->ip_dst));
757 * Checksum routine for Internet Protocol family headers (C Version)
759 in_cksum(u_short *addr, int len)
761 register int nleft = len;
762 register u_short *w = addr;
763 register u_short answer;
764 register int sum = 0;
767 * Our algorithm is simple, using a 32 bit accumulator (sum),
768 * we add sequential 16 bit words to it, and at the end, fold
769 * back all the carry bits from the top 16 bits into the lower
777 /* mop up an odd byte, if necessary */
782 * add back carry outs from top 16 bits to low 16 bits
784 sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
785 sum += (sum >> 16); /* add carry */
786 answer = ~sum; /* truncate to 16 bits */
792 * Subtract 2 timeval structs: out = out - in.
793 * Out is assumed to be >= in.
796 tvsub(register struct timeval *out, register struct timeval *in)
798 if ((out->tv_usec -= in->tv_usec) < 0) {
800 out->tv_usec += 1000000;
802 out->tv_sec -= in->tv_sec;
807 * Construct an Internet address representation.
808 * If the nflag has been supplied, give
809 * numeric value, otherwise try for symbolic name.
812 inetname(struct in_addr in)
815 static char line[50];
817 static char domain[MAXHOSTNAMELEN + 1];
818 static int first = 1;
820 if (first && !nflag) {
822 if (gethostname(domain, MAXHOSTNAMELEN) == 0 &&
823 (cp = strchr(domain, '.')))
824 (void) strcpy(domain, cp + 1);
829 if (!nflag && in.s_addr != INADDR_ANY) {
830 hp = gethostbyaddr((char *)&in, sizeof (in), AF_INET);
832 if ((cp = strchr(hp->h_name, '.')) &&
833 !strcmp(cp + 1, domain))
839 (void) strcpy(line, cp);
841 in.s_addr = ntohl(in.s_addr);
842 #define C(x) ((x) & 0xff)
843 Sprintf(line, "%lu.%lu.%lu.%lu", C(in.s_addr >> 24),
844 C(in.s_addr >> 16), C(in.s_addr >> 8), C(in.s_addr));