tftpd.c revision 1.15 1 /* $NetBSD: tftpd.c,v 1.15 1998/09/20 04:44:55 explorer Exp $ */
2
3 /*
4 * Copyright (c) 1983, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by the University of
18 * California, Berkeley and its contributors.
19 * 4. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 #include <sys/cdefs.h>
37 #ifndef lint
38 __COPYRIGHT("@(#) Copyright (c) 1983, 1993\n\
39 The Regents of the University of California. All rights reserved.\n");
40 #if 0
41 static char sccsid[] = "@(#)tftpd.c 8.1 (Berkeley) 6/4/93";
42 #else
43 __RCSID("$NetBSD: tftpd.c,v 1.15 1998/09/20 04:44:55 explorer Exp $");
44 #endif
45 #endif /* not lint */
46
47 /*
48 * Trivial file transfer protocol server.
49 *
50 * This version includes many modifications by Jim Guyton
51 * <guyton@rand-unix>.
52 */
53
54 #include <sys/param.h>
55 #include <sys/ioctl.h>
56 #include <sys/stat.h>
57 #include <sys/socket.h>
58
59 #include <signal.h>
60 #include <fcntl.h>
61
62 #include <netinet/in.h>
63 #include <arpa/tftp.h>
64 #include <arpa/inet.h>
65
66 #include <ctype.h>
67 #include <errno.h>
68 #include <fcntl.h>
69 #include <grp.h>
70 #include <netdb.h>
71 #include <pwd.h>
72 #include <setjmp.h>
73 #include <signal.h>
74 #include <stdio.h>
75 #include <stdlib.h>
76 #include <string.h>
77 #include <syslog.h>
78 #include <unistd.h>
79
80 #include "tftpsubs.h"
81
82 #define DEFAULTUSER "nobody"
83
84 #define TIMEOUT 5
85
86 extern char *__progname;
87 int peer;
88 int rexmtval = TIMEOUT;
89 int maxtimeout = 5*TIMEOUT;
90
91 #define PKTSIZE SEGSIZE+4
92 char buf[PKTSIZE];
93 char ackbuf[PKTSIZE];
94 struct sockaddr_in from;
95 int fromlen;
96
97 /*
98 * Null-terminated directory prefix list for absolute pathname requests and
99 * search list for relative pathname requests.
100 *
101 * MAXDIRS should be at least as large as the number of arguments that
102 * inetd allows (currently 20).
103 */
104 #define MAXDIRS 20
105 static struct dirlist {
106 char *name;
107 int len;
108 } dirs[MAXDIRS+1];
109 static int suppress_naks;
110 static int logging;
111 static int secure;
112 static char *securedir;
113
114 struct formats;
115
116 static void tftp __P((struct tftphdr *, int));
117 static const char *errtomsg __P((int));
118 static void nak __P((int));
119 static char *verifyhost __P((struct sockaddr_in *));
120 static void usage __P((void));
121 void timer __P((int));
122 void sendfile __P((struct formats *));
123 void recvfile __P((struct formats *));
124 void justquit __P((int));
125 int validate_access __P((char **, int));
126 int main __P((int, char **));
127
128 struct formats {
129 char *f_mode;
130 int (*f_validate) __P((char **, int));
131 void (*f_send) __P((struct formats *));
132 void (*f_recv) __P((struct formats *));
133 int f_convert;
134 } formats[] = {
135 { "netascii", validate_access, sendfile, recvfile, 1 },
136 { "octet", validate_access, sendfile, recvfile, 0 },
137 { 0 }
138 };
139
140 static void
141 usage()
142 {
143 syslog(LOG_ERR,
144 "Usage: %s [-ln] [-u user] [-g group] [-s directory] [directory ...]",
145 __progname);
146 exit(1);
147 }
148
149 int
150 main(argc, argv)
151 int argc;
152 char **argv;
153 {
154 struct passwd *pwent;
155 struct group *grent;
156 struct tftphdr *tp;
157 int n = 0;
158 int ch, on;
159 int fd = 0;
160 struct sockaddr_in sin;
161 int len;
162 char *tgtuser, *tgtgroup, *ep;
163 uid_t curuid, tgtuid;
164 gid_t curgid, tgtgid;
165 long nid;
166
167 openlog("tftpd", LOG_PID | LOG_NDELAY, LOG_DAEMON);
168 tgtuser = DEFAULTUSER;
169 tgtgroup = NULL;
170 curuid = getuid();
171 curgid = getgid();
172
173 while ((ch = getopt(argc, argv, "g:lns:u:")) != -1)
174 switch (ch) {
175
176 case 'g':
177 tgtgroup = optarg;
178 break;
179
180 case 'l':
181 logging = 1;
182 break;
183
184 case 'n':
185 suppress_naks = 1;
186 break;
187
188 case 's':
189 secure = 1;
190 securedir = optarg;
191 break;
192
193 case 'u':
194 tgtuser = optarg;
195 break;
196
197 default:
198 usage();
199 break;
200 }
201
202 if (optind < argc) {
203 struct dirlist *dirp;
204
205 /* Get list of directory prefixes. Skip relative pathnames. */
206 for (dirp = dirs; optind < argc && dirp < &dirs[MAXDIRS];
207 optind++) {
208 if (argv[optind][0] == '/') {
209 dirp->name = argv[optind];
210 dirp->len = strlen(dirp->name);
211 dirp++;
212 }
213 }
214 }
215
216 if (*tgtuser == '\0' || (tgtgroup != NULL && *tgtgroup == '\0'))
217 usage();
218
219 nid = (strtol(tgtuser, &ep, 10));
220 if (*ep == '\0') {
221 if (nid > UID_MAX) {
222 syslog(LOG_ERR, "uid %ld is too large", nid);
223 exit(1);
224 }
225 pwent = getpwuid((uid_t)nid);
226 } else
227 pwent = getpwnam(tgtuser);
228 if (pwent == NULL) {
229 syslog(LOG_ERR, "unknown user `%s'", tgtuser);
230 exit(1);
231 }
232 tgtuid = pwent->pw_uid;
233 tgtgid = pwent->pw_gid;
234
235 if (tgtgroup != NULL) {
236 nid = (strtol(tgtgroup, &ep, 10));
237 if (*ep == '\0') {
238 if (nid > GID_MAX) {
239 syslog(LOG_ERR, "gid %ld is too large", nid);
240 exit(1);
241 }
242 grent = getgrgid((gid_t)nid);
243 } else
244 grent = getgrnam(tgtgroup);
245 if (grent != NULL)
246 tgtgid = grent->gr_gid;
247 else {
248 syslog(LOG_ERR, "unknown group `%s'", tgtgroup);
249 exit(1);
250 }
251 }
252
253 if (secure) {
254 if (chdir(securedir) < 0) {
255 syslog(LOG_ERR, "chdir %s: %m", securedir);
256 exit(1);
257 }
258 if (chroot(".")) {
259 syslog(LOG_ERR, "chroot: %m");
260 exit(1);
261 }
262 }
263
264 syslog(LOG_DEBUG, "running as user `%s' (%d), group `%s' (%d)",
265 tgtuser, tgtuid, tgtgroup ? tgtgroup : "(unspecified)" , tgtgid);
266 if (curgid != tgtgid) {
267 if (setgid(tgtgid)) {
268 syslog(LOG_ERR, "setgid to %d: %m", (int)tgtgid);
269 exit(1);
270 }
271 if (setgroups(0, NULL)) {
272 syslog(LOG_ERR, "setgroups: %m");
273 exit(1);
274 }
275 }
276
277 if (curuid != tgtuid) {
278 if (setuid(tgtuid)) {
279 syslog(LOG_ERR, "setuid to %d: %m", (int)tgtuid);
280 exit(1);
281 }
282 }
283
284 on = 1;
285 if (ioctl(fd, FIONBIO, &on) < 0) {
286 syslog(LOG_ERR, "ioctl(FIONBIO): %m");
287 exit(1);
288 }
289 fromlen = sizeof (from);
290 n = recvfrom(fd, buf, sizeof (buf), 0,
291 (struct sockaddr *)&from, &fromlen);
292 if (n < 0) {
293 syslog(LOG_ERR, "recvfrom: %m");
294 exit(1);
295 }
296 /*
297 * Now that we have read the message out of the UDP
298 * socket, we fork and exit. Thus, inetd will go back
299 * to listening to the tftp port, and the next request
300 * to come in will start up a new instance of tftpd.
301 *
302 * We do this so that inetd can run tftpd in "wait" mode.
303 * The problem with tftpd running in "nowait" mode is that
304 * inetd may get one or more successful "selects" on the
305 * tftp port before we do our receive, so more than one
306 * instance of tftpd may be started up. Worse, if tftpd
307 * break before doing the above "recvfrom", inetd would
308 * spawn endless instances, clogging the system.
309 */
310 {
311 int pid;
312 int i, j;
313
314 for (i = 1; i < 20; i++) {
315 pid = fork();
316 if (pid < 0) {
317 sleep(i);
318 /*
319 * flush out to most recently sent request.
320 *
321 * This may drop some request, but those
322 * will be resent by the clients when
323 * they timeout. The positive effect of
324 * this flush is to (try to) prevent more
325 * than one tftpd being started up to service
326 * a single request from a single client.
327 */
328 j = sizeof from;
329 i = recvfrom(fd, buf, sizeof (buf), 0,
330 (struct sockaddr *)&from, &j);
331 if (i > 0) {
332 n = i;
333 fromlen = j;
334 }
335 } else {
336 break;
337 }
338 }
339 if (pid < 0) {
340 syslog(LOG_ERR, "fork: %m");
341 exit(1);
342 } else if (pid != 0) {
343 exit(0);
344 }
345 }
346
347 from.sin_len = sizeof(struct sockaddr_in);
348 from.sin_family = AF_INET;
349
350 /*
351 * remember what address this was sent to, so we can respond on the
352 * same interface
353 */
354 len = sizeof(sin);
355 if (getsockname(fd, (struct sockaddr *)&sin, &len) == 0)
356 sin.sin_port = 0;
357 else {
358 memset(&sin, 0, sizeof(sin));
359 sin.sin_family = AF_INET;
360 }
361
362 alarm(0);
363 close(fd);
364 close(1);
365 peer = socket(AF_INET, SOCK_DGRAM, 0);
366 if (peer < 0) {
367 syslog(LOG_ERR, "socket: %m");
368 exit(1);
369 }
370 if (bind(peer, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
371 syslog(LOG_ERR, "bind: %m");
372 exit(1);
373 }
374 if (connect(peer, (struct sockaddr *)&from, sizeof(from)) < 0) {
375 syslog(LOG_ERR, "connect: %m");
376 exit(1);
377 }
378 tp = (struct tftphdr *)buf;
379 tp->th_opcode = ntohs(tp->th_opcode);
380 if (tp->th_opcode == RRQ || tp->th_opcode == WRQ)
381 tftp(tp, n);
382 exit(1);
383 }
384
385 /*
386 * Handle initial connection protocol.
387 */
388 static void
389 tftp(tp, size)
390 struct tftphdr *tp;
391 int size;
392 {
393 char *cp;
394 int first = 1, ecode;
395 struct formats *pf;
396 char *filename, *mode = NULL; /* XXX gcc */
397
398 filename = cp = tp->th_stuff;
399 again:
400 while (cp < buf + size) {
401 if (*cp == '\0')
402 break;
403 cp++;
404 }
405 if (*cp != '\0') {
406 nak(EBADOP);
407 exit(1);
408 }
409 if (first) {
410 mode = ++cp;
411 first = 0;
412 goto again;
413 }
414 for (cp = mode; *cp; cp++)
415 if (isupper(*cp))
416 *cp = tolower(*cp);
417 for (pf = formats; pf->f_mode; pf++)
418 if (strcmp(pf->f_mode, mode) == 0)
419 break;
420 if (pf->f_mode == 0) {
421 nak(EBADOP);
422 exit(1);
423 }
424 ecode = (*pf->f_validate)(&filename, tp->th_opcode);
425 if (logging) {
426 syslog(LOG_INFO, "%s: %s request for %s: %s",
427 verifyhost(&from),
428 tp->th_opcode == WRQ ? "write" : "read",
429 filename, errtomsg(ecode));
430 }
431 if (ecode) {
432 /*
433 * Avoid storms of naks to a RRQ broadcast for a relative
434 * bootfile pathname from a diskless Sun.
435 */
436 if (suppress_naks && *filename != '/' && ecode == ENOTFOUND)
437 exit(0);
438 nak(ecode);
439 exit(1);
440 }
441 if (tp->th_opcode == WRQ)
442 (*pf->f_recv)(pf);
443 else
444 (*pf->f_send)(pf);
445 exit(0);
446 }
447
448
449 FILE *file;
450
451 /*
452 * Validate file access. Since we
453 * have no uid or gid, for now require
454 * file to exist and be publicly
455 * readable/writable.
456 * If we were invoked with arguments
457 * from inetd then the file must also be
458 * in one of the given directory prefixes.
459 * Note also, full path name must be
460 * given as we have no login directory.
461 */
462 int
463 validate_access(filep, mode)
464 char **filep;
465 int mode;
466 {
467 struct stat stbuf;
468 int fd;
469 struct dirlist *dirp;
470 static char pathname[MAXPATHLEN];
471 char *filename = *filep;
472
473 /*
474 * Prevent tricksters from getting around the directory restrictions
475 */
476 if (strstr(filename, "/../"))
477 return (EACCESS);
478
479 if (*filename == '/') {
480 /*
481 * Allow the request if it's in one of the approved locations.
482 * Special case: check the null prefix ("/") by looking
483 * for length = 1 and relying on the arg. processing that
484 * it's a /.
485 */
486 for (dirp = dirs; dirp->name != NULL; dirp++) {
487 if (dirp->len == 1 ||
488 (!strncmp(filename, dirp->name, dirp->len) &&
489 filename[dirp->len] == '/'))
490 break;
491 }
492 /* If directory list is empty, allow access to any file */
493 if (dirp->name == NULL && dirp != dirs)
494 return (EACCESS);
495 if (stat(filename, &stbuf) < 0)
496 return (errno == ENOENT ? ENOTFOUND : EACCESS);
497 if (!S_ISREG(stbuf.st_mode))
498 return (ENOTFOUND);
499 if (mode == RRQ) {
500 if ((stbuf.st_mode & S_IROTH) == 0)
501 return (EACCESS);
502 } else {
503 if ((stbuf.st_mode & S_IWOTH) == 0)
504 return (EACCESS);
505 }
506 } else {
507 int err;
508
509 /*
510 * Relative file name: search the approved locations for it.
511 * Don't allow write requests or ones that avoid directory
512 * restrictions.
513 */
514
515 if (mode != RRQ || !strncmp(filename, "../", 3))
516 return (EACCESS);
517
518 /*
519 * If the file exists in one of the directories and isn't
520 * readable, continue looking. However, change the error code
521 * to give an indication that the file exists.
522 */
523 err = ENOTFOUND;
524 if (dirs[0].name != NULL) {
525 for (dirp = dirs; dirp->name != NULL; dirp++) {
526 snprintf(pathname, sizeof pathname, "%s/%s",
527 dirp->name, filename);
528 if (stat(pathname, &stbuf) == 0 &&
529 (stbuf.st_mode & S_IFMT) == S_IFREG) {
530 if ((stbuf.st_mode & S_IROTH) != 0)
531 break;
532 err = EACCESS;
533 }
534 }
535 if (dirp->name == NULL)
536 return (err);
537 *filep = filename = pathname;
538 } else
539 *filep = filename;
540 }
541 fd = open(filename, mode == RRQ ? 0 : 1);
542 if (fd < 0)
543 return (errno + 100);
544 file = fdopen(fd, (mode == RRQ)? "r":"w");
545 if (file == NULL) {
546 return errno+100;
547 }
548 return (0);
549 }
550
551 int timeout;
552 jmp_buf timeoutbuf;
553
554 void
555 timer(dummy)
556 int dummy;
557 {
558
559 timeout += rexmtval;
560 if (timeout >= maxtimeout)
561 exit(1);
562 longjmp(timeoutbuf, 1);
563 }
564
565 /*
566 * Send the requested file.
567 */
568 void
569 sendfile(pf)
570 struct formats *pf;
571 {
572 struct tftphdr *dp;
573 struct tftphdr *ap; /* ack packet */
574 int size, n;
575 volatile int block;
576
577 signal(SIGALRM, timer);
578 dp = r_init();
579 ap = (struct tftphdr *)ackbuf;
580 block = 1;
581 do {
582 size = readit(file, &dp, pf->f_convert);
583 if (size < 0) {
584 nak(errno + 100);
585 goto abort;
586 }
587 dp->th_opcode = htons((u_short)DATA);
588 dp->th_block = htons((u_short)block);
589 timeout = 0;
590 (void)setjmp(timeoutbuf);
591
592 send_data:
593 if (send(peer, dp, size + 4, 0) != size + 4) {
594 syslog(LOG_ERR, "tftpd: write: %m");
595 goto abort;
596 }
597 read_ahead(file, pf->f_convert);
598 for ( ; ; ) {
599 alarm(rexmtval); /* read the ack */
600 n = recv(peer, ackbuf, sizeof (ackbuf), 0);
601 alarm(0);
602 if (n < 0) {
603 syslog(LOG_ERR, "tftpd: read: %m");
604 goto abort;
605 }
606 ap->th_opcode = ntohs((u_short)ap->th_opcode);
607 ap->th_block = ntohs((u_short)ap->th_block);
608
609 if (ap->th_opcode == ERROR)
610 goto abort;
611
612 if (ap->th_opcode == ACK) {
613 if (ap->th_block == block)
614 break;
615 /* Re-synchronize with the other side */
616 (void) synchnet(peer);
617 if (ap->th_block == (block -1))
618 goto send_data;
619 }
620
621 }
622 block++;
623 } while (size == SEGSIZE);
624 abort:
625 (void) fclose(file);
626 }
627
628 void
629 justquit(dummy)
630 int dummy;
631 {
632 exit(0);
633 }
634
635 /*
636 * Receive a file.
637 */
638 void
639 recvfile(pf)
640 struct formats *pf;
641 {
642 struct tftphdr *dp;
643 struct tftphdr *ap; /* ack buffer */
644 int n, size;
645 volatile int block;
646
647 signal(SIGALRM, timer);
648 dp = w_init();
649 ap = (struct tftphdr *)ackbuf;
650 block = 0;
651 do {
652 timeout = 0;
653 ap->th_opcode = htons((u_short)ACK);
654 ap->th_block = htons((u_short)block);
655 block++;
656 (void) setjmp(timeoutbuf);
657 send_ack:
658 if (send(peer, ackbuf, 4, 0) != 4) {
659 syslog(LOG_ERR, "tftpd: write: %m");
660 goto abort;
661 }
662 write_behind(file, pf->f_convert);
663 for ( ; ; ) {
664 alarm(rexmtval);
665 n = recv(peer, dp, PKTSIZE, 0);
666 alarm(0);
667 if (n < 0) { /* really? */
668 syslog(LOG_ERR, "tftpd: read: %m");
669 goto abort;
670 }
671 dp->th_opcode = ntohs((u_short)dp->th_opcode);
672 dp->th_block = ntohs((u_short)dp->th_block);
673 if (dp->th_opcode == ERROR)
674 goto abort;
675 if (dp->th_opcode == DATA) {
676 if (dp->th_block == block) {
677 break; /* normal */
678 }
679 /* Re-synchronize with the other side */
680 (void) synchnet(peer);
681 if (dp->th_block == (block-1))
682 goto send_ack; /* rexmit */
683 }
684 }
685 /* size = write(file, dp->th_data, n - 4); */
686 size = writeit(file, &dp, n - 4, pf->f_convert);
687 if (size != (n-4)) { /* ahem */
688 if (size < 0) nak(errno + 100);
689 else nak(ENOSPACE);
690 goto abort;
691 }
692 } while (size == SEGSIZE);
693 write_behind(file, pf->f_convert);
694 (void) fclose(file); /* close data file */
695
696 ap->th_opcode = htons((u_short)ACK); /* send the "final" ack */
697 ap->th_block = htons((u_short)(block));
698 (void) send(peer, ackbuf, 4, 0);
699
700 signal(SIGALRM, justquit); /* just quit on timeout */
701 alarm(rexmtval);
702 n = recv(peer, buf, sizeof (buf), 0); /* normally times out and quits */
703 alarm(0);
704 if (n >= 4 && /* if read some data */
705 dp->th_opcode == DATA && /* and got a data block */
706 block == dp->th_block) { /* then my last ack was lost */
707 (void) send(peer, ackbuf, 4, 0); /* resend final ack */
708 }
709 abort:
710 return;
711 }
712
713 const struct errmsg {
714 int e_code;
715 const char *e_msg;
716 } errmsgs[] = {
717 { EUNDEF, "Undefined error code" },
718 { ENOTFOUND, "File not found" },
719 { EACCESS, "Access violation" },
720 { ENOSPACE, "Disk full or allocation exceeded" },
721 { EBADOP, "Illegal TFTP operation" },
722 { EBADID, "Unknown transfer ID" },
723 { EEXISTS, "File already exists" },
724 { ENOUSER, "No such user" },
725 { -1, 0 }
726 };
727
728 static const char *
729 errtomsg(error)
730 int error;
731 {
732 static char buf[20];
733 const struct errmsg *pe;
734
735 if (error == 0)
736 return "success";
737 for (pe = errmsgs; pe->e_code >= 0; pe++)
738 if (pe->e_code == error)
739 return pe->e_msg;
740 sprintf(buf, "error %d", error);
741 return buf;
742 }
743
744 /*
745 * Send a nak packet (error message).
746 * Error code passed in is one of the
747 * standard TFTP codes, or a UNIX errno
748 * offset by 100.
749 */
750 static void
751 nak(error)
752 int error;
753 {
754 struct tftphdr *tp;
755 int length;
756 const struct errmsg *pe;
757
758 tp = (struct tftphdr *)buf;
759 tp->th_opcode = htons((u_short)ERROR);
760 for (pe = errmsgs; pe->e_code >= 0; pe++)
761 if (pe->e_code == error)
762 break;
763 if (pe->e_code < 0) {
764 tp->th_code = EUNDEF; /* set 'undef' errorcode */
765 strcpy(tp->th_msg, strerror(error - 100));
766 } else {
767 tp->th_code = htons((u_short)error);
768 strcpy(tp->th_msg, pe->e_msg);
769 }
770 length = strlen(pe->e_msg);
771 tp->th_msg[length] = '\0';
772 length += 5;
773 if (send(peer, buf, length, 0) != length)
774 syslog(LOG_ERR, "nak: %m");
775 }
776
777 static char *
778 verifyhost(fromp)
779 struct sockaddr_in *fromp;
780 {
781 struct hostent *hp;
782
783 hp = gethostbyaddr((char *)&fromp->sin_addr, sizeof (fromp->sin_addr),
784 fromp->sin_family);
785 if (hp)
786 return hp->h_name;
787 else
788 return inet_ntoa(fromp->sin_addr);
789 }
790