xref: /freebsd/libexec/tftpd/tftpd.c (revision 145992504973bd16cf3518af9ba5ce185fefa82a)
1 /*
2  * Copyright (c) 1983, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #ifndef lint
35 static const char copyright[] =
36 "@(#) Copyright (c) 1983, 1993\n\
37 	The Regents of the University of California.  All rights reserved.\n";
38 #endif /* not lint */
39 
40 #ifndef lint
41 #if 0
42 static char sccsid[] = "@(#)tftpd.c	8.1 (Berkeley) 6/4/93";
43 #endif
44 #endif /* not lint */
45 #include <sys/cdefs.h>
46 __FBSDID("$FreeBSD$");
47 
48 /*
49  * Trivial file transfer protocol server.
50  *
51  * This version includes many modifications by Jim Guyton
52  * <guyton@rand-unix>.
53  */
54 
55 #include <sys/param.h>
56 #include <sys/ioctl.h>
57 #include <sys/stat.h>
58 #include <sys/socket.h>
59 
60 #include <netinet/in.h>
61 #include <arpa/tftp.h>
62 
63 #include <ctype.h>
64 #include <errno.h>
65 #include <fcntl.h>
66 #include <netdb.h>
67 #include <pwd.h>
68 #include <stdio.h>
69 #include <stdlib.h>
70 #include <string.h>
71 #include <syslog.h>
72 #include <tcpd.h>
73 #include <unistd.h>
74 
75 #include "tftp-file.h"
76 #include "tftp-io.h"
77 #include "tftp-utils.h"
78 #include "tftp-transfer.h"
79 #include "tftp-options.h"
80 
81 static void	tftp_wrq(int peer, char *, ssize_t);
82 static void	tftp_rrq(int peer, char *, ssize_t);
83 
84 /*
85  * Null-terminated directory prefix list for absolute pathname requests and
86  * search list for relative pathname requests.
87  *
88  * MAXDIRS should be at least as large as the number of arguments that
89  * inetd allows (currently 20).
90  */
91 #define MAXDIRS	20
92 static struct dirlist {
93 	const char	*name;
94 	int	len;
95 } dirs[MAXDIRS+1];
96 static int	suppress_naks;
97 static int	logging;
98 static int	ipchroot;
99 static int	create_new = 0;
100 static const char *newfile_format = "%Y%m%d";
101 static int	increase_name = 0;
102 static mode_t	mask = S_IWGRP | S_IWOTH;
103 
104 struct formats;
105 static void	tftp_recvfile(int peer, const char *mode);
106 static void	tftp_xmitfile(int peer, const char *mode);
107 static int	validate_access(int peer, char **, int);
108 static char	peername[NI_MAXHOST];
109 
110 static FILE *file;
111 
112 static struct formats {
113 	const char	*f_mode;
114 	int	f_convert;
115 } formats[] = {
116 	{ "netascii",	1 },
117 	{ "octet",	0 },
118 	{ NULL,		0 }
119 };
120 
121 int
122 main(int argc, char *argv[])
123 {
124 	struct tftphdr *tp;
125 	int		peer;
126 	socklen_t	peerlen, len;
127 	ssize_t		n;
128 	int		ch;
129 	char		*chroot_dir = NULL;
130 	struct passwd	*nobody;
131 	const char	*chuser = "nobody";
132 	char		recvbuffer[MAXPKTSIZE];
133 	int		allow_ro = 1, allow_wo = 1;
134 
135 	tzset();			/* syslog in localtime */
136 	acting_as_client = 0;
137 
138 	tftp_openlog("tftpd", LOG_PID | LOG_NDELAY, LOG_FTP);
139 	while ((ch = getopt(argc, argv, "cCd:F:lnoOp:s:u:U:wW")) != -1) {
140 		switch (ch) {
141 		case 'c':
142 			ipchroot = 1;
143 			break;
144 		case 'C':
145 			ipchroot = 2;
146 			break;
147 		case 'd':
148 			if (atoi(optarg) != 0)
149 				debug += atoi(optarg);
150 			else
151 				debug |= debug_finds(optarg);
152 			break;
153 		case 'F':
154 			newfile_format = optarg;
155 			break;
156 		case 'l':
157 			logging = 1;
158 			break;
159 		case 'n':
160 			suppress_naks = 1;
161 			break;
162 		case 'o':
163 			options_rfc_enabled = 0;
164 			break;
165 		case 'O':
166 			options_extra_enabled = 0;
167 			break;
168 		case 'p':
169 			packetdroppercentage = atoi(optarg);
170 			tftp_log(LOG_INFO,
171 			    "Randomly dropping %d out of 100 packets",
172 			    packetdroppercentage);
173 			break;
174 		case 's':
175 			chroot_dir = optarg;
176 			break;
177 		case 'u':
178 			chuser = optarg;
179 			break;
180 		case 'U':
181 			mask = strtol(optarg, NULL, 0);
182 			break;
183 		case 'w':
184 			create_new = 1;
185 			break;
186 		case 'W':
187 			create_new = 1;
188 			increase_name = 1;
189 			break;
190 		default:
191 			tftp_log(LOG_WARNING,
192 				"ignoring unknown option -%c", ch);
193 		}
194 	}
195 	if (optind < argc) {
196 		struct dirlist *dirp;
197 
198 		/* Get list of directory prefixes. Skip relative pathnames. */
199 		for (dirp = dirs; optind < argc && dirp < &dirs[MAXDIRS];
200 		     optind++) {
201 			if (argv[optind][0] == '/') {
202 				dirp->name = argv[optind];
203 				dirp->len  = strlen(dirp->name);
204 				dirp++;
205 			}
206 		}
207 	}
208 	else if (chroot_dir) {
209 		dirs->name = "/";
210 		dirs->len = 1;
211 	}
212 	if (ipchroot > 0 && chroot_dir == NULL) {
213 		tftp_log(LOG_ERR, "-c requires -s");
214 		exit(1);
215 	}
216 
217 	umask(mask);
218 
219 	{
220 		int on = 1;
221 		if (ioctl(0, FIONBIO, &on) < 0) {
222 			tftp_log(LOG_ERR, "ioctl(FIONBIO): %s", strerror(errno));
223 			exit(1);
224 		}
225 	}
226 
227 	/* Find out who we are talking to and what we are going to do */
228 	peerlen = sizeof(peer_sock);
229 	n = recvfrom(0, recvbuffer, MAXPKTSIZE, 0,
230 	    (struct sockaddr *)&peer_sock, &peerlen);
231 	if (n < 0) {
232 		tftp_log(LOG_ERR, "recvfrom: %s", strerror(errno));
233 		exit(1);
234 	}
235 	getnameinfo((struct sockaddr *)&peer_sock, peer_sock.ss_len,
236 	    peername, sizeof(peername), NULL, 0, NI_NUMERICHOST);
237 
238 	/*
239 	 * Now that we have read the message out of the UDP
240 	 * socket, we fork and exit.  Thus, inetd will go back
241 	 * to listening to the tftp port, and the next request
242 	 * to come in will start up a new instance of tftpd.
243 	 *
244 	 * We do this so that inetd can run tftpd in "wait" mode.
245 	 * The problem with tftpd running in "nowait" mode is that
246 	 * inetd may get one or more successful "selects" on the
247 	 * tftp port before we do our receive, so more than one
248 	 * instance of tftpd may be started up.  Worse, if tftpd
249 	 * break before doing the above "recvfrom", inetd would
250 	 * spawn endless instances, clogging the system.
251 	 */
252 	{
253 		int i, pid;
254 
255 		for (i = 1; i < 20; i++) {
256 		    pid = fork();
257 		    if (pid < 0) {
258 				sleep(i);
259 				/*
260 				 * flush out to most recently sent request.
261 				 *
262 				 * This may drop some request, but those
263 				 * will be resent by the clients when
264 				 * they timeout.  The positive effect of
265 				 * this flush is to (try to) prevent more
266 				 * than one tftpd being started up to service
267 				 * a single request from a single client.
268 				 */
269 				peerlen = sizeof peer_sock;
270 				i = recvfrom(0, recvbuffer, MAXPKTSIZE, 0,
271 				    (struct sockaddr *)&peer_sock, &peerlen);
272 				if (i > 0) {
273 					n = i;
274 				}
275 		    } else {
276 				break;
277 		    }
278 		}
279 		if (pid < 0) {
280 			tftp_log(LOG_ERR, "fork: %s", strerror(errno));
281 			exit(1);
282 		} else if (pid != 0) {
283 			exit(0);
284 		}
285 	}
286 
287 	/*
288 	 * See if the client is allowed to talk to me.
289 	 * (This needs to be done before the chroot())
290 	 */
291 	{
292 		struct request_info req;
293 
294 		request_init(&req, RQ_CLIENT_ADDR, peername, 0);
295 		request_set(&req, RQ_DAEMON, "tftpd", 0);
296 
297 		if (hosts_access(&req) == 0) {
298 			if (debug&DEBUG_ACCESS)
299 				tftp_log(LOG_WARNING,
300 				    "Access denied by 'tftpd' entry "
301 				    "in /etc/hosts.allow");
302 
303 			/*
304 			 * Full access might be disabled, but maybe the
305 			 * client is allowed to do read-only access.
306 			 */
307 			request_set(&req, RQ_DAEMON, "tftpd-ro", 0);
308 			allow_ro = hosts_access(&req);
309 
310 			request_set(&req, RQ_DAEMON, "tftpd-wo", 0);
311 			allow_wo = hosts_access(&req);
312 
313 			if (allow_ro == 0 && allow_wo == 0) {
314 				tftp_log(LOG_WARNING,
315 				    "Unauthorized access from %s", peername);
316 				exit(1);
317 			}
318 
319 			if (debug&DEBUG_ACCESS) {
320 				if (allow_ro)
321 					tftp_log(LOG_WARNING,
322 					    "But allowed readonly access "
323 					    "via 'tftpd-ro' entry");
324 				if (allow_wo)
325 					tftp_log(LOG_WARNING,
326 					    "But allowed writeonly access "
327 					    "via 'tftpd-wo' entry");
328 			}
329 		} else
330 			if (debug&DEBUG_ACCESS)
331 				tftp_log(LOG_WARNING,
332 				    "Full access allowed"
333 				    "in /etc/hosts.allow");
334 	}
335 
336 	/*
337 	 * Since we exit here, we should do that only after the above
338 	 * recvfrom to keep inetd from constantly forking should there
339 	 * be a problem.  See the above comment about system clogging.
340 	 */
341 	if (chroot_dir) {
342 		if (ipchroot > 0) {
343 			char *tempchroot;
344 			struct stat sb;
345 			int statret;
346 			struct sockaddr_storage ss;
347 			char hbuf[NI_MAXHOST];
348 
349 			statret = -1;
350 			memcpy(&ss, &peer_sock, peer_sock.ss_len);
351 			unmappedaddr((struct sockaddr_in6 *)&ss);
352 			getnameinfo((struct sockaddr *)&ss, ss.ss_len,
353 				    hbuf, sizeof(hbuf), NULL, 0,
354 				    NI_NUMERICHOST);
355 			asprintf(&tempchroot, "%s/%s", chroot_dir, hbuf);
356 			if (ipchroot == 2)
357 				statret = stat(tempchroot, &sb);
358 			if (ipchroot == 1 ||
359 			    (statret == 0 && (sb.st_mode & S_IFDIR)))
360 				chroot_dir = tempchroot;
361 		}
362 		/* Must get this before chroot because /etc might go away */
363 		if ((nobody = getpwnam(chuser)) == NULL) {
364 			tftp_log(LOG_ERR, "%s: no such user", chuser);
365 			exit(1);
366 		}
367 		if (chroot(chroot_dir)) {
368 			tftp_log(LOG_ERR, "chroot: %s: %s",
369 			    chroot_dir, strerror(errno));
370 			exit(1);
371 		}
372 		chdir("/");
373 		setgroups(1, &nobody->pw_gid);
374 		if (setuid(nobody->pw_uid) != 0) {
375 			tftp_log(LOG_ERR, "setuid failed");
376 			exit(1);
377 		}
378 	}
379 
380 	len = sizeof(me_sock);
381 	if (getsockname(0, (struct sockaddr *)&me_sock, &len) == 0) {
382 		switch (me_sock.ss_family) {
383 		case AF_INET:
384 			((struct sockaddr_in *)&me_sock)->sin_port = 0;
385 			break;
386 		case AF_INET6:
387 			((struct sockaddr_in6 *)&me_sock)->sin6_port = 0;
388 			break;
389 		default:
390 			/* unsupported */
391 			break;
392 		}
393 	} else {
394 		memset(&me_sock, 0, sizeof(me_sock));
395 		me_sock.ss_family = peer_sock.ss_family;
396 		me_sock.ss_len = peer_sock.ss_len;
397 	}
398 	close(0);
399 	close(1);
400 	peer = socket(peer_sock.ss_family, SOCK_DGRAM, 0);
401 	if (peer < 0) {
402 		tftp_log(LOG_ERR, "socket: %s", strerror(errno));
403 		exit(1);
404 	}
405 	if (bind(peer, (struct sockaddr *)&me_sock, me_sock.ss_len) < 0) {
406 		tftp_log(LOG_ERR, "bind: %s", strerror(errno));
407 		exit(1);
408 	}
409 
410 	tp = (struct tftphdr *)recvbuffer;
411 	tp->th_opcode = ntohs(tp->th_opcode);
412 	if (tp->th_opcode == RRQ) {
413 		if (allow_ro)
414 			tftp_rrq(peer, tp->th_stuff, n - 1);
415 		else {
416 			tftp_log(LOG_WARNING,
417 			    "%s read access denied", peername);
418 			exit(1);
419 		}
420 	}
421 	if (tp->th_opcode == WRQ) {
422 		if (allow_wo)
423 			tftp_wrq(peer, tp->th_stuff, n - 1);
424 		else {
425 			tftp_log(LOG_WARNING,
426 			    "%s write access denied", peername);
427 			exit(1);
428 		}
429 	}
430 	exit(1);
431 }
432 
433 static void
434 reduce_path(char *fn)
435 {
436 	char *slash, *ptr;
437 
438 	/* Reduce all "/+./" to "/" (just in case we've got "/./../" later */
439 	while ((slash = strstr(fn, "/./")) != NULL) {
440 		for (ptr = slash; ptr > fn && ptr[-1] == '/'; ptr--)
441 			;
442 		slash += 2;
443 		while (*slash)
444 			*++ptr = *++slash;
445 	}
446 
447 	/* Now reduce all "/something/+../" to "/" */
448 	while ((slash = strstr(fn, "/../")) != NULL) {
449 		if (slash == fn)
450 			break;
451 		for (ptr = slash; ptr > fn && ptr[-1] == '/'; ptr--)
452 			;
453 		for (ptr--; ptr >= fn; ptr--)
454 			if (*ptr == '/')
455 				break;
456 		if (ptr < fn)
457 			break;
458 		slash += 3;
459 		while (*slash)
460 			*++ptr = *++slash;
461 	}
462 }
463 
464 static char *
465 parse_header(int peer, char *recvbuffer, ssize_t size,
466 	char **filename, char **mode)
467 {
468 	char	*cp;
469 	int	i;
470 	struct formats *pf;
471 
472 	*mode = NULL;
473 	cp = recvbuffer;
474 
475 	i = get_field(peer, recvbuffer, size);
476 	if (i >= PATH_MAX) {
477 		tftp_log(LOG_ERR, "Bad option - filename too long");
478 		send_error(peer, EBADOP);
479 		exit(1);
480 	}
481 	*filename = recvbuffer;
482 	tftp_log(LOG_INFO, "Filename: '%s'", *filename);
483 	cp += i;
484 
485 	i = get_field(peer, cp, size);
486 	*mode = cp;
487 	cp += i;
488 
489 	/* Find the file transfer mode */
490 	for (cp = *mode; *cp; cp++)
491 		if (isupper(*cp))
492 			*cp = tolower(*cp);
493 	for (pf = formats; pf->f_mode; pf++)
494 		if (strcmp(pf->f_mode, *mode) == 0)
495 			break;
496 	if (pf->f_mode == NULL) {
497 		tftp_log(LOG_ERR,
498 		    "Bad option - Unknown transfer mode (%s)", *mode);
499 		send_error(peer, EBADOP);
500 		exit(1);
501 	}
502 	tftp_log(LOG_INFO, "Mode: '%s'", *mode);
503 
504 	return (cp + 1);
505 }
506 
507 /*
508  * WRQ - receive a file from the client
509  */
510 void
511 tftp_wrq(int peer, char *recvbuffer, ssize_t size)
512 {
513 	char *cp;
514 	int has_options = 0, ecode;
515 	char *filename, *mode;
516 	char fnbuf[PATH_MAX];
517 
518 	cp = parse_header(peer, recvbuffer, size, &filename, &mode);
519 	size -= (cp - recvbuffer) + 1;
520 
521 	strcpy(fnbuf, filename);
522 	reduce_path(fnbuf);
523 	filename = fnbuf;
524 
525 	if (size > 0) {
526 		if (options_rfc_enabled)
527 			has_options = !parse_options(peer, cp, size);
528 		else
529 			tftp_log(LOG_INFO, "Options found but not enabled");
530 	}
531 
532 	ecode = validate_access(peer, &filename, WRQ);
533 	if (ecode == 0) {
534 		if (has_options)
535 			send_oack(peer);
536 		else
537 			send_ack(peer, 0);
538 	}
539 	if (logging) {
540 		tftp_log(LOG_INFO, "%s: write request for %s: %s", peername,
541 			    filename, errtomsg(ecode));
542 	}
543 
544 	tftp_recvfile(peer, mode);
545 	exit(0);
546 }
547 
548 /*
549  * RRQ - send a file to the client
550  */
551 void
552 tftp_rrq(int peer, char *recvbuffer, ssize_t size)
553 {
554 	char *cp;
555 	int has_options = 0, ecode;
556 	char *filename, *mode;
557 	char	fnbuf[PATH_MAX];
558 
559 	cp = parse_header(peer, recvbuffer, size, &filename, &mode);
560 	size -= (cp - recvbuffer) + 1;
561 
562 	strcpy(fnbuf, filename);
563 	reduce_path(fnbuf);
564 	filename = fnbuf;
565 
566 	if (size > 0) {
567 		if (options_rfc_enabled)
568 			has_options = !parse_options(peer, cp, size);
569 		else
570 			tftp_log(LOG_INFO, "Options found but not enabled");
571 	}
572 
573 	ecode = validate_access(peer, &filename, RRQ);
574 	if (ecode == 0) {
575 		if (has_options) {
576 			int n;
577 			char lrecvbuffer[MAXPKTSIZE];
578 			struct tftphdr *rp = (struct tftphdr *)lrecvbuffer;
579 
580 			send_oack(peer);
581 			n = receive_packet(peer, lrecvbuffer, MAXPKTSIZE,
582 				NULL, timeoutpacket);
583 			if (n < 0) {
584 				if (debug&DEBUG_SIMPLE)
585 					tftp_log(LOG_DEBUG, "Aborting: %s",
586 					    rp_strerror(n));
587 				return;
588 			}
589 			if (rp->th_opcode != ACK) {
590 				if (debug&DEBUG_SIMPLE)
591 					tftp_log(LOG_DEBUG,
592 					    "Expected ACK, got %s on OACK",
593 					    packettype(rp->th_opcode));
594 				return;
595 			}
596 		}
597 	}
598 
599 	if (logging)
600 		tftp_log(LOG_INFO, "%s: read request for %s: %s", peername,
601 			    filename, errtomsg(ecode));
602 
603 	if (ecode) {
604 		/*
605 		 * Avoid storms of naks to a RRQ broadcast for a relative
606 		 * bootfile pathname from a diskless Sun.
607 		 */
608 		if (suppress_naks && *filename != '/' && ecode == ENOTFOUND)
609 			exit(0);
610 		send_error(peer, ecode);
611 		exit(1);
612 	}
613 	tftp_xmitfile(peer, mode);
614 }
615 
616 /*
617  * Find the next value for YYYYMMDD.nn when the file to be written should
618  * be unique. Due to the limitations of nn, we will fail if nn reaches 100.
619  * Besides, that is four updates per hour on a file, which is kind of
620  * execessive anyway.
621  */
622 static int
623 find_next_name(char *filename, int *fd)
624 {
625 	int i;
626 	time_t tval;
627 	size_t len;
628 	struct tm lt;
629 	char yyyymmdd[MAXPATHLEN];
630 	char newname[MAXPATHLEN];
631 
632 	/* Create the YYYYMMDD part of the filename */
633 	time(&tval);
634 	lt = *localtime(&tval);
635 	len = strftime(yyyymmdd, sizeof(yyyymmdd), newfile_format, &lt);
636 	if (len == 0) {
637 		syslog(LOG_WARNING,
638 			"Filename suffix too long (%d characters maximum)",
639 			MAXPATHLEN);
640 		return (EACCESS);
641 	}
642 
643 	/* Make sure the new filename is not too long */
644 	if (strlen(filename) > MAXPATHLEN - len - 5) {
645 		syslog(LOG_WARNING,
646 			"Filename too long (%zd characters, %zd maximum)",
647 			strlen(filename), MAXPATHLEN - len - 5);
648 		return (EACCESS);
649 	}
650 
651 	/* Find the first file which doesn't exist */
652 	for (i = 0; i < 100; i++) {
653 		sprintf(newname, "%s.%s.%02d", filename, yyyymmdd, i);
654 		*fd = open(newname,
655 		    O_WRONLY | O_CREAT | O_EXCL,
656 		    S_IRUSR | S_IWUSR | S_IRGRP |
657 		    S_IWGRP | S_IROTH | S_IWOTH);
658 		if (*fd > 0)
659 			return 0;
660 	}
661 
662 	return (EEXIST);
663 }
664 
665 /*
666  * Validate file access.  Since we
667  * have no uid or gid, for now require
668  * file to exist and be publicly
669  * readable/writable.
670  * If we were invoked with arguments
671  * from inetd then the file must also be
672  * in one of the given directory prefixes.
673  * Note also, full path name must be
674  * given as we have no login directory.
675  */
676 int
677 validate_access(int peer, char **filep, int mode)
678 {
679 	struct stat stbuf;
680 	int	fd;
681 	int	error;
682 	struct dirlist *dirp;
683 	static char pathname[MAXPATHLEN];
684 	char *filename = *filep;
685 
686 	/*
687 	 * Prevent tricksters from getting around the directory restrictions
688 	 */
689 	if (strstr(filename, "/../"))
690 		return (EACCESS);
691 
692 	if (*filename == '/') {
693 		/*
694 		 * Allow the request if it's in one of the approved locations.
695 		 * Special case: check the null prefix ("/") by looking
696 		 * for length = 1 and relying on the arg. processing that
697 		 * it's a /.
698 		 */
699 		for (dirp = dirs; dirp->name != NULL; dirp++) {
700 			if (dirp->len == 1 ||
701 			    (!strncmp(filename, dirp->name, dirp->len) &&
702 			     filename[dirp->len] == '/'))
703 				    break;
704 		}
705 		/* If directory list is empty, allow access to any file */
706 		if (dirp->name == NULL && dirp != dirs)
707 			return (EACCESS);
708 		if (stat(filename, &stbuf) < 0)
709 			return (errno == ENOENT ? ENOTFOUND : EACCESS);
710 		if ((stbuf.st_mode & S_IFMT) != S_IFREG)
711 			return (ENOTFOUND);
712 		if (mode == RRQ) {
713 			if ((stbuf.st_mode & S_IROTH) == 0)
714 				return (EACCESS);
715 		} else {
716 			if ((stbuf.st_mode & S_IWOTH) == 0)
717 				return (EACCESS);
718 		}
719 	} else {
720 		int err;
721 
722 		/*
723 		 * Relative file name: search the approved locations for it.
724 		 * Don't allow write requests that avoid directory
725 		 * restrictions.
726 		 */
727 
728 		if (!strncmp(filename, "../", 3))
729 			return (EACCESS);
730 
731 		/*
732 		 * If the file exists in one of the directories and isn't
733 		 * readable, continue looking. However, change the error code
734 		 * to give an indication that the file exists.
735 		 */
736 		err = ENOTFOUND;
737 		for (dirp = dirs; dirp->name != NULL; dirp++) {
738 			snprintf(pathname, sizeof(pathname), "%s/%s",
739 				dirp->name, filename);
740 			if (stat(pathname, &stbuf) == 0 &&
741 			    (stbuf.st_mode & S_IFMT) == S_IFREG) {
742 				if ((stbuf.st_mode & S_IROTH) != 0) {
743 					break;
744 				}
745 				err = EACCESS;
746 			}
747 		}
748 		if (dirp->name != NULL)
749 			*filep = filename = pathname;
750 		else if (mode == RRQ)
751 			return (err);
752 	}
753 
754 	/*
755 	 * This option is handled here because it (might) require(s) the
756 	 * size of the file.
757 	 */
758 	option_tsize(peer, NULL, mode, &stbuf);
759 
760 	if (mode == RRQ)
761 		fd = open(filename, O_RDONLY);
762 	else {
763 		if (create_new) {
764 			if (increase_name) {
765 				error = find_next_name(filename, &fd);
766 				if (error > 0)
767 					return (error + 100);
768 			} else
769 				fd = open(filename,
770 				    O_WRONLY | O_TRUNC | O_CREAT,
771 				    S_IRUSR | S_IWUSR | S_IRGRP |
772 				    S_IWGRP | S_IROTH | S_IWOTH );
773 		} else
774 			fd = open(filename, O_WRONLY | O_TRUNC);
775 	}
776 	if (fd < 0)
777 		return (errno + 100);
778 	file = fdopen(fd, (mode == RRQ)? "r":"w");
779 	if (file == NULL) {
780 		close(fd);
781 		return (errno + 100);
782 	}
783 	return (0);
784 }
785 
786 static void
787 tftp_xmitfile(int peer, const char *mode)
788 {
789 	uint16_t block;
790 	time_t now;
791 	struct tftp_stats ts;
792 
793 	now = time(NULL);
794 	if (debug&DEBUG_SIMPLE)
795 		tftp_log(LOG_DEBUG, "Transmitting file");
796 
797 	read_init(0, file, mode);
798 	block = 1;
799 	tftp_send(peer, &block, &ts);
800 	read_close();
801 	if (debug&DEBUG_SIMPLE)
802 		tftp_log(LOG_INFO, "Sent %d bytes in %d seconds",
803 		    ts.amount, time(NULL) - now);
804 }
805 
806 static void
807 tftp_recvfile(int peer, const char *mode)
808 {
809 	uint16_t block;
810 	struct timeval now1, now2;
811 	struct tftp_stats ts;
812 
813 	gettimeofday(&now1, NULL);
814 	if (debug&DEBUG_SIMPLE)
815 		tftp_log(LOG_DEBUG, "Receiving file");
816 
817 	write_init(0, file, mode);
818 
819 	block = 0;
820 	tftp_receive(peer, &block, &ts, NULL, 0);
821 
822 	write_close();
823 	gettimeofday(&now2, NULL);
824 
825 	if (debug&DEBUG_SIMPLE) {
826 		double f;
827 		if (now1.tv_usec > now2.tv_usec) {
828 			now2.tv_usec += 1000000;
829 			now2.tv_sec--;
830 		}
831 
832 		f = now2.tv_sec - now1.tv_sec +
833 		    (now2.tv_usec - now1.tv_usec) / 100000.0;
834 		tftp_log(LOG_INFO,
835 		    "Download of %d bytes in %d blocks completed after %0.1f seconds\n",
836 		    ts.amount, block, f);
837 	}
838 
839 	return;
840 }
841