xref: /freebsd/libexec/tftpd/tftpd.c (revision 2e3f49888ec8851bafb22011533217487764fdb0)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
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. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 /*
33  * Trivial file transfer protocol server.
34  *
35  * This version includes many modifications by Jim Guyton
36  * <guyton@rand-unix>.
37  */
38 
39 #include <sys/param.h>
40 #include <sys/ioctl.h>
41 #include <sys/socket.h>
42 #include <sys/stat.h>
43 #include <sys/time.h>
44 
45 #include <netinet/in.h>
46 #include <arpa/tftp.h>
47 
48 #include <ctype.h>
49 #include <errno.h>
50 #include <fcntl.h>
51 #include <netdb.h>
52 #include <pwd.h>
53 #include <stdint.h>
54 #include <stdio.h>
55 #include <stdlib.h>
56 #include <string.h>
57 #include <syslog.h>
58 #include <time.h>
59 #include <unistd.h>
60 
61 #include "tftp-file.h"
62 #include "tftp-io.h"
63 #include "tftp-utils.h"
64 #include "tftp-transfer.h"
65 #include "tftp-options.h"
66 
67 #ifdef	LIBWRAP
68 #include <tcpd.h>
69 #endif
70 
71 static void	tftp_wrq(int peer, char *, ssize_t);
72 static void	tftp_rrq(int peer, char *, ssize_t);
73 
74 /*
75  * Null-terminated directory prefix list for absolute pathname requests and
76  * search list for relative pathname requests.
77  *
78  * MAXDIRS should be at least as large as the number of arguments that
79  * inetd allows (currently 20).
80  */
81 #define MAXDIRS	20
82 static struct dirlist {
83 	const char	*name;
84 	int	len;
85 } dirs[MAXDIRS+1];
86 static int	suppress_naks;
87 static int	logging;
88 static int	ipchroot;
89 static int	check_woth = 1;
90 static int	create_new = 0;
91 static const char *newfile_format = "%Y%m%d";
92 static int	increase_name = 0;
93 static mode_t	mask = S_IWGRP | S_IWOTH;
94 
95 struct formats;
96 static void	tftp_recvfile(int peer, const char *mode);
97 static void	tftp_xmitfile(int peer, const char *mode);
98 static int	validate_access(int peer, char **, int);
99 static char	peername[NI_MAXHOST];
100 
101 static FILE *file;
102 
103 static struct formats {
104 	const char	*f_mode;
105 	int	f_convert;
106 } formats[] = {
107 	{ "netascii",	1 },
108 	{ "octet",	0 },
109 	{ NULL,		0 }
110 };
111 
112 int
113 main(int argc, char *argv[])
114 {
115 	struct tftphdr *tp;
116 	int		peer;
117 	socklen_t	peerlen, len;
118 	ssize_t		n;
119 	int		ch;
120 	char		*chroot_dir = NULL;
121 	struct passwd	*nobody;
122 	const char	*chuser = "nobody";
123 	char		recvbuffer[MAXPKTSIZE];
124 	int		allow_ro = 1, allow_wo = 1, on = 1;
125 	pid_t		pid;
126 
127 	tzset();			/* syslog in localtime */
128 	acting_as_client = 0;
129 
130 	tftp_openlog("tftpd", LOG_PID | LOG_NDELAY, LOG_FTP);
131 	while ((ch = getopt(argc, argv, "cCd::F:lnoOp:s:Su:U:wW")) != -1) {
132 		switch (ch) {
133 		case 'c':
134 			ipchroot = 1;
135 			break;
136 		case 'C':
137 			ipchroot = 2;
138 			break;
139 		case 'd':
140 			if (optarg == NULL)
141 				debug++;
142 			else if (atoi(optarg) != 0)
143 				debug += atoi(optarg);
144 			else
145 				debug |= debug_finds(optarg);
146 			break;
147 		case 'F':
148 			newfile_format = optarg;
149 			break;
150 		case 'l':
151 			logging = 1;
152 			break;
153 		case 'n':
154 			suppress_naks = 1;
155 			break;
156 		case 'o':
157 			options_rfc_enabled = 0;
158 			break;
159 		case 'O':
160 			options_extra_enabled = 0;
161 			break;
162 		case 'p':
163 			packetdroppercentage = atoi(optarg);
164 			tftp_log(LOG_INFO,
165 			    "Randomly dropping %d out of 100 packets",
166 			    packetdroppercentage);
167 			break;
168 		case 's':
169 			chroot_dir = optarg;
170 			break;
171 		case 'S':
172 			check_woth = -1;
173 			break;
174 		case 'u':
175 			chuser = optarg;
176 			break;
177 		case 'U':
178 			mask = strtol(optarg, NULL, 0);
179 			break;
180 		case 'w':
181 			create_new = 1;
182 			break;
183 		case 'W':
184 			create_new = 1;
185 			increase_name = 1;
186 			break;
187 		default:
188 			tftp_log(LOG_WARNING,
189 				"ignoring unknown option -%c", ch);
190 		}
191 	}
192 	if (optind < argc) {
193 		struct dirlist *dirp;
194 
195 		/* Get list of directory prefixes. Skip relative pathnames. */
196 		for (dirp = dirs; optind < argc && dirp < &dirs[MAXDIRS];
197 		     optind++) {
198 			if (argv[optind][0] == '/') {
199 				dirp->name = argv[optind];
200 				dirp->len  = strlen(dirp->name);
201 				dirp++;
202 			}
203 		}
204 	}
205 	else if (chroot_dir) {
206 		dirs->name = "/";
207 		dirs->len = 1;
208 	}
209 	if (ipchroot > 0 && chroot_dir == NULL) {
210 		tftp_log(LOG_ERR, "-c requires -s");
211 		exit(1);
212 	}
213 
214 	umask(mask);
215 
216 	if (ioctl(0, FIONBIO, &on) < 0) {
217 		tftp_log(LOG_ERR, "ioctl(FIONBIO): %s", strerror(errno));
218 		exit(1);
219 	}
220 
221 	/* Find out who we are talking to and what we are going to do */
222 	peerlen = sizeof(peer_sock);
223 	n = recvfrom(0, recvbuffer, MAXPKTSIZE, 0,
224 	    (struct sockaddr *)&peer_sock, &peerlen);
225 	if (n < 0) {
226 		tftp_log(LOG_ERR, "recvfrom: %s", strerror(errno));
227 		exit(1);
228 	}
229 	getnameinfo((struct sockaddr *)&peer_sock, peer_sock.ss_len,
230 	    peername, sizeof(peername), NULL, 0, NI_NUMERICHOST);
231 
232 	/*
233 	 * Now that we have read the message out of the UDP
234 	 * socket, we fork and exit.  Thus, inetd will go back
235 	 * to listening to the tftp port, and the next request
236 	 * to come in will start up a new instance of tftpd.
237 	 *
238 	 * We do this so that inetd can run tftpd in "wait" mode.
239 	 * The problem with tftpd running in "nowait" mode is that
240 	 * inetd may get one or more successful "selects" on the
241 	 * tftp port before we do our receive, so more than one
242 	 * instance of tftpd may be started up.  Worse, if tftpd
243 	 * break before doing the above "recvfrom", inetd would
244 	 * spawn endless instances, clogging the system.
245 	 */
246 	pid = fork();
247 	if (pid < 0) {
248 		tftp_log(LOG_ERR, "fork: %s", strerror(errno));
249 		exit(1);
250 	} else if (pid != 0) {
251 		exit(0);
252 	}
253 	/* child */
254 
255 #ifdef	LIBWRAP
256 	/*
257 	 * See if the client is allowed to talk to me.
258 	 * (This needs to be done before the chroot())
259 	 */
260 	{
261 		struct request_info req;
262 
263 		request_init(&req, RQ_CLIENT_ADDR, peername, 0);
264 		request_set(&req, RQ_DAEMON, "tftpd", 0);
265 
266 		if (hosts_access(&req) == 0) {
267 			if (debug & DEBUG_ACCESS)
268 				tftp_log(LOG_WARNING,
269 				    "Access denied by 'tftpd' entry "
270 				    "in /etc/hosts.allow");
271 
272 			/*
273 			 * Full access might be disabled, but maybe the
274 			 * client is allowed to do read-only access.
275 			 */
276 			request_set(&req, RQ_DAEMON, "tftpd-ro", 0);
277 			allow_ro = hosts_access(&req);
278 
279 			request_set(&req, RQ_DAEMON, "tftpd-wo", 0);
280 			allow_wo = hosts_access(&req);
281 
282 			if (allow_ro == 0 && allow_wo == 0) {
283 				tftp_log(LOG_WARNING,
284 				    "Unauthorized access from %s", peername);
285 				exit(1);
286 			}
287 
288 			if (debug & DEBUG_ACCESS) {
289 				if (allow_ro)
290 					tftp_log(LOG_WARNING,
291 					    "But allowed readonly access "
292 					    "via 'tftpd-ro' entry");
293 				if (allow_wo)
294 					tftp_log(LOG_WARNING,
295 					    "But allowed writeonly access "
296 					    "via 'tftpd-wo' entry");
297 			}
298 		} else
299 			if (debug & DEBUG_ACCESS)
300 				tftp_log(LOG_WARNING,
301 				    "Full access allowed"
302 				    "in /etc/hosts.allow");
303 	}
304 #endif
305 
306 	/*
307 	 * Since we exit here, we should do that only after the above
308 	 * recvfrom to keep inetd from constantly forking should there
309 	 * be a problem.  See the above comment about system clogging.
310 	 */
311 	if (chroot_dir) {
312 		if (ipchroot > 0) {
313 			char *tempchroot;
314 			struct stat sb;
315 			int statret;
316 			struct sockaddr_storage ss;
317 			char hbuf[NI_MAXHOST];
318 
319 			statret = -1;
320 			memcpy(&ss, &peer_sock, peer_sock.ss_len);
321 			unmappedaddr((struct sockaddr_in6 *)&ss);
322 			getnameinfo((struct sockaddr *)&ss, ss.ss_len,
323 				    hbuf, sizeof(hbuf), NULL, 0,
324 				    NI_NUMERICHOST);
325 			asprintf(&tempchroot, "%s/%s", chroot_dir, hbuf);
326 			if (ipchroot == 2)
327 				statret = stat(tempchroot, &sb);
328 			if (ipchroot == 1 ||
329 			    (statret == 0 && (sb.st_mode & S_IFDIR)))
330 				chroot_dir = tempchroot;
331 		}
332 		/* Must get this before chroot because /etc might go away */
333 		if ((nobody = getpwnam(chuser)) == NULL) {
334 			tftp_log(LOG_ERR, "%s: no such user", chuser);
335 			exit(1);
336 		}
337 		if (chroot(chroot_dir)) {
338 			tftp_log(LOG_ERR, "chroot: %s: %s",
339 			    chroot_dir, strerror(errno));
340 			exit(1);
341 		}
342 		if (chdir("/") != 0) {
343 			tftp_log(LOG_ERR, "chdir: %s", strerror(errno));
344 			exit(1);
345 		}
346 		if (setgroups(1, &nobody->pw_gid) != 0) {
347 			tftp_log(LOG_ERR, "setgroups failed");
348 			exit(1);
349 		}
350 		if (setuid(nobody->pw_uid) != 0) {
351 			tftp_log(LOG_ERR, "setuid failed");
352 			exit(1);
353 		}
354 		if (check_woth == -1)
355 			check_woth = 0;
356 	}
357 	if (check_woth == -1)
358 		check_woth = 1;
359 
360 	len = sizeof(me_sock);
361 	if (getsockname(0, (struct sockaddr *)&me_sock, &len) == 0) {
362 		switch (me_sock.ss_family) {
363 		case AF_INET:
364 			((struct sockaddr_in *)&me_sock)->sin_port = 0;
365 			break;
366 		case AF_INET6:
367 			((struct sockaddr_in6 *)&me_sock)->sin6_port = 0;
368 			break;
369 		default:
370 			/* unsupported */
371 			break;
372 		}
373 	} else {
374 		memset(&me_sock, 0, sizeof(me_sock));
375 		me_sock.ss_family = peer_sock.ss_family;
376 		me_sock.ss_len = peer_sock.ss_len;
377 	}
378 	close(STDIN_FILENO);
379 	close(STDOUT_FILENO);
380 	close(STDERR_FILENO);
381 	peer = socket(peer_sock.ss_family, SOCK_DGRAM, 0);
382 	if (peer < 0) {
383 		tftp_log(LOG_ERR, "socket: %s", strerror(errno));
384 		exit(1);
385 	}
386 	if (bind(peer, (struct sockaddr *)&me_sock, me_sock.ss_len) < 0) {
387 		tftp_log(LOG_ERR, "bind: %s", strerror(errno));
388 		exit(1);
389 	}
390 
391 	tp = (struct tftphdr *)recvbuffer;
392 	tp->th_opcode = ntohs(tp->th_opcode);
393 	if (tp->th_opcode == RRQ) {
394 		if (allow_ro)
395 			tftp_rrq(peer, tp->th_stuff, n - 1);
396 		else {
397 			tftp_log(LOG_WARNING,
398 			    "%s read access denied", peername);
399 			exit(1);
400 		}
401 	} else if (tp->th_opcode == WRQ) {
402 		if (allow_wo)
403 			tftp_wrq(peer, tp->th_stuff, n - 1);
404 		else {
405 			tftp_log(LOG_WARNING,
406 			    "%s write access denied", peername);
407 			exit(1);
408 		}
409 	} else
410 		send_error(peer, EBADOP);
411 	exit(1);
412 }
413 
414 static void
415 reduce_path(char *fn)
416 {
417 	char *slash, *ptr;
418 
419 	/* Reduce all "/+./" to "/" (just in case we've got "/./../" later */
420 	while ((slash = strstr(fn, "/./")) != NULL) {
421 		for (ptr = slash; ptr > fn && ptr[-1] == '/'; ptr--)
422 			;
423 		slash += 2;
424 		while (*slash)
425 			*++ptr = *++slash;
426 	}
427 
428 	/* Now reduce all "/something/+../" to "/" */
429 	while ((slash = strstr(fn, "/../")) != NULL) {
430 		if (slash == fn)
431 			break;
432 		for (ptr = slash; ptr > fn && ptr[-1] == '/'; ptr--)
433 			;
434 		for (ptr--; ptr >= fn; ptr--)
435 			if (*ptr == '/')
436 				break;
437 		if (ptr < fn)
438 			break;
439 		slash += 3;
440 		while (*slash)
441 			*++ptr = *++slash;
442 	}
443 }
444 
445 static char *
446 parse_header(int peer, char *recvbuffer, ssize_t size,
447 	char **filename, char **mode)
448 {
449 	char	*cp;
450 	int	i;
451 	struct formats *pf;
452 
453 	*mode = NULL;
454 	cp = recvbuffer;
455 
456 	i = get_field(peer, recvbuffer, size);
457 	if (i >= PATH_MAX) {
458 		tftp_log(LOG_ERR, "Bad option - filename too long");
459 		send_error(peer, EBADOP);
460 		exit(1);
461 	}
462 	*filename = recvbuffer;
463 	tftp_log(LOG_INFO, "Filename: '%s'", *filename);
464 	cp += i;
465 
466 	i = get_field(peer, cp, size);
467 	*mode = cp;
468 	cp += i;
469 
470 	/* Find the file transfer mode */
471 	for (cp = *mode; *cp; cp++)
472 		if (isupper(*cp))
473 			*cp = tolower(*cp);
474 	for (pf = formats; pf->f_mode; pf++)
475 		if (strcmp(pf->f_mode, *mode) == 0)
476 			break;
477 	if (pf->f_mode == NULL) {
478 		tftp_log(LOG_ERR,
479 		    "Bad option - Unknown transfer mode (%s)", *mode);
480 		send_error(peer, EBADOP);
481 		exit(1);
482 	}
483 	tftp_log(LOG_INFO, "Mode: '%s'", *mode);
484 
485 	return (cp + 1);
486 }
487 
488 /*
489  * WRQ - receive a file from the client
490  */
491 void
492 tftp_wrq(int peer, char *recvbuffer, ssize_t size)
493 {
494 	char *cp;
495 	int has_options = 0, ecode;
496 	char *filename, *mode;
497 	char fnbuf[PATH_MAX];
498 
499 	cp = parse_header(peer, recvbuffer, size, &filename, &mode);
500 	size -= (cp - recvbuffer) + 1;
501 
502 	strlcpy(fnbuf, filename, sizeof(fnbuf));
503 	reduce_path(fnbuf);
504 	filename = fnbuf;
505 
506 	if (size > 0) {
507 		if (options_rfc_enabled)
508 			has_options = !parse_options(peer, cp, size);
509 		else
510 			tftp_log(LOG_INFO, "Options found but not enabled");
511 	}
512 
513 	ecode = validate_access(peer, &filename, WRQ);
514 	if (ecode == 0) {
515 		if (has_options)
516 			send_oack(peer);
517 		else
518 			send_ack(peer, 0);
519 	}
520 	if (logging) {
521 		tftp_log(LOG_INFO, "%s: write request for %s: %s", peername,
522 			    filename, errtomsg(ecode));
523 	}
524 
525 	if (ecode) {
526 		send_error(peer, ecode);
527 		exit(1);
528 	}
529 	tftp_recvfile(peer, mode);
530 	exit(0);
531 }
532 
533 /*
534  * RRQ - send a file to the client
535  */
536 void
537 tftp_rrq(int peer, char *recvbuffer, ssize_t size)
538 {
539 	char *cp;
540 	int has_options = 0, ecode;
541 	char *filename, *mode;
542 	char	fnbuf[PATH_MAX];
543 
544 	cp = parse_header(peer, recvbuffer, size, &filename, &mode);
545 	size -= (cp - recvbuffer) + 1;
546 
547 	strlcpy(fnbuf, filename, sizeof(fnbuf));
548 	reduce_path(fnbuf);
549 	filename = fnbuf;
550 
551 	if (size > 0) {
552 		if (options_rfc_enabled)
553 			has_options = !parse_options(peer, cp, size);
554 		else
555 			tftp_log(LOG_INFO, "Options found but not enabled");
556 	}
557 
558 	ecode = validate_access(peer, &filename, RRQ);
559 	if (ecode == 0) {
560 		if (has_options) {
561 			int n;
562 			char lrecvbuffer[MAXPKTSIZE];
563 			struct tftphdr *rp = (struct tftphdr *)lrecvbuffer;
564 
565 			send_oack(peer);
566 			n = receive_packet(peer, lrecvbuffer, MAXPKTSIZE,
567 				NULL, timeoutpacket);
568 			if (n < 0) {
569 				if (debug & DEBUG_SIMPLE)
570 					tftp_log(LOG_DEBUG, "Aborting: %s",
571 					    rp_strerror(n));
572 				return;
573 			}
574 			if (rp->th_opcode != ACK) {
575 				if (debug & DEBUG_SIMPLE)
576 					tftp_log(LOG_DEBUG,
577 					    "Expected ACK, got %s on OACK",
578 					    packettype(rp->th_opcode));
579 				return;
580 			}
581 		}
582 	}
583 
584 	if (logging)
585 		tftp_log(LOG_INFO, "%s: read request for %s: %s", peername,
586 			    filename, errtomsg(ecode));
587 
588 	if (ecode) {
589 		/*
590 		 * Avoid storms of naks to a RRQ broadcast for a relative
591 		 * bootfile pathname from a diskless Sun.
592 		 */
593 		if (suppress_naks && *filename != '/' && ecode == ENOTFOUND)
594 			exit(0);
595 		send_error(peer, ecode);
596 		exit(1);
597 	}
598 	tftp_xmitfile(peer, mode);
599 }
600 
601 /*
602  * Find the next value for YYYYMMDD.nn when the file to be written should
603  * be unique. Due to the limitations of nn, we will fail if nn reaches 100.
604  * Besides, that is four updates per hour on a file, which is kind of
605  * execessive anyway.
606  */
607 static int
608 find_next_name(char *filename, int *fd)
609 {
610 	int i;
611 	time_t tval;
612 	size_t len;
613 	struct tm lt;
614 	char yyyymmdd[MAXPATHLEN];
615 	char newname[MAXPATHLEN];
616 
617 	/* Create the YYYYMMDD part of the filename */
618 	time(&tval);
619 	lt = *localtime(&tval);
620 	len = strftime(yyyymmdd, sizeof(yyyymmdd), newfile_format, &lt);
621 	if (len == 0) {
622 		syslog(LOG_WARNING,
623 			"Filename suffix too long (%d characters maximum)",
624 			MAXPATHLEN);
625 		return (EACCESS);
626 	}
627 
628 	/* Make sure the new filename is not too long */
629 	if (strlen(filename) > MAXPATHLEN - len - 5) {
630 		syslog(LOG_WARNING,
631 			"Filename too long (%zd characters, %zd maximum)",
632 			strlen(filename), MAXPATHLEN - len - 5);
633 		return (EACCESS);
634 	}
635 
636 	/* Find the first file which doesn't exist */
637 	for (i = 0; i < 100; i++) {
638 		sprintf(newname, "%s.%s.%02d", filename, yyyymmdd, i);
639 		*fd = open(newname,
640 		    O_WRONLY | O_CREAT | O_EXCL,
641 		    S_IRUSR | S_IWUSR | S_IRGRP |
642 		    S_IWGRP | S_IROTH | S_IWOTH);
643 		if (*fd > 0)
644 			return 0;
645 	}
646 
647 	return (EEXIST);
648 }
649 
650 /*
651  * Validate file access.  Since we
652  * have no uid or gid, for now require
653  * file to exist and be publicly
654  * readable/writable.
655  * If we were invoked with arguments
656  * from inetd then the file must also be
657  * in one of the given directory prefixes.
658  * Note also, full path name must be
659  * given as we have no login directory.
660  */
661 int
662 validate_access(int peer, char **filep, int mode)
663 {
664 	struct stat stbuf;
665 	int	fd;
666 	int	error;
667 	struct dirlist *dirp;
668 	static char pathname[MAXPATHLEN];
669 	char *filename = *filep;
670 
671 	/*
672 	 * Prevent tricksters from getting around the directory restrictions
673 	 */
674 	if (strstr(filename, "/../"))
675 		return (EACCESS);
676 
677 	if (*filename == '/') {
678 		/*
679 		 * Allow the request if it's in one of the approved locations.
680 		 * Special case: check the null prefix ("/") by looking
681 		 * for length = 1 and relying on the arg. processing that
682 		 * it's a /.
683 		 */
684 		for (dirp = dirs; dirp->name != NULL; dirp++) {
685 			if (dirp->len == 1 ||
686 			    (!strncmp(filename, dirp->name, dirp->len) &&
687 			     filename[dirp->len] == '/'))
688 				    break;
689 		}
690 		/* If directory list is empty, allow access to any file */
691 		if (dirp->name == NULL && dirp != dirs)
692 			return (EACCESS);
693 		if (stat(filename, &stbuf) < 0)
694 			return (errno == ENOENT ? ENOTFOUND : EACCESS);
695 		if ((stbuf.st_mode & S_IFMT) != S_IFREG)
696 			return (ENOTFOUND);
697 		if (mode == RRQ) {
698 			if ((stbuf.st_mode & S_IROTH) == 0)
699 				return (EACCESS);
700 		} else {
701 			if (check_woth && ((stbuf.st_mode & S_IWOTH) == 0))
702 				return (EACCESS);
703 		}
704 	} else {
705 		int err;
706 
707 		/*
708 		 * Relative file name: search the approved locations for it.
709 		 * Don't allow write requests that avoid directory
710 		 * restrictions.
711 		 */
712 
713 		if (!strncmp(filename, "../", 3))
714 			return (EACCESS);
715 
716 		/*
717 		 * If the file exists in one of the directories and isn't
718 		 * readable, continue looking. However, change the error code
719 		 * to give an indication that the file exists.
720 		 */
721 		err = ENOTFOUND;
722 		for (dirp = dirs; dirp->name != NULL; dirp++) {
723 			snprintf(pathname, sizeof(pathname), "%s/%s",
724 				dirp->name, filename);
725 			if (stat(pathname, &stbuf) == 0 &&
726 			    (stbuf.st_mode & S_IFMT) == S_IFREG) {
727 				if (mode == RRQ) {
728 					if ((stbuf.st_mode & S_IROTH) != 0)
729 						break;
730 				} else {
731 					if (!check_woth || ((stbuf.st_mode & S_IWOTH) != 0))
732 						break;
733 				}
734 				err = EACCESS;
735 			}
736 		}
737 		if (dirp->name != NULL)
738 			*filep = filename = pathname;
739 		else if (mode == RRQ)
740 			return (err);
741 		else if (err != ENOTFOUND || !create_new)
742 			return (err);
743 	}
744 
745 	/*
746 	 * This option is handled here because it (might) require(s) the
747 	 * size of the file.
748 	 */
749 	option_tsize(peer, NULL, mode, &stbuf);
750 
751 	if (mode == RRQ)
752 		fd = open(filename, O_RDONLY);
753 	else {
754 		if (create_new) {
755 			if (increase_name) {
756 				error = find_next_name(filename, &fd);
757 				if (error > 0)
758 					return (error + 100);
759 			} else
760 				fd = open(filename,
761 				    O_WRONLY | O_TRUNC | O_CREAT,
762 				    S_IRUSR | S_IWUSR | S_IRGRP |
763 				    S_IWGRP | S_IROTH | S_IWOTH );
764 		} else
765 			fd = open(filename, O_WRONLY | O_TRUNC);
766 	}
767 	if (fd < 0)
768 		return (errno + 100);
769 	file = fdopen(fd, (mode == RRQ)? "r":"w");
770 	if (file == NULL) {
771 		close(fd);
772 		return (errno + 100);
773 	}
774 	return (0);
775 }
776 
777 static void
778 tftp_xmitfile(int peer, const char *mode)
779 {
780 	uint16_t block;
781 	time_t now;
782 	struct tftp_stats ts;
783 
784 	memset(&ts, 0, sizeof(ts));
785 	now = time(NULL);
786 	if (debug & DEBUG_SIMPLE)
787 		tftp_log(LOG_DEBUG, "Transmitting file");
788 
789 	read_init(0, file, mode);
790 	block = 1;
791 	tftp_send(peer, &block, &ts);
792 	read_close();
793 	if (debug & DEBUG_SIMPLE)
794 		tftp_log(LOG_INFO, "Sent %jd bytes in %jd seconds",
795 		    (intmax_t)ts.amount, (intmax_t)time(NULL) - now);
796 }
797 
798 static void
799 tftp_recvfile(int peer, const char *mode)
800 {
801 	uint16_t block;
802 	struct timeval now1, now2;
803 	struct tftp_stats ts;
804 
805 	gettimeofday(&now1, NULL);
806 	if (debug & DEBUG_SIMPLE)
807 		tftp_log(LOG_DEBUG, "Receiving file");
808 
809 	write_init(0, file, mode);
810 
811 	block = 0;
812 	tftp_receive(peer, &block, &ts, NULL, 0);
813 
814 	gettimeofday(&now2, NULL);
815 
816 	if (debug & DEBUG_SIMPLE) {
817 		double f;
818 		if (now1.tv_usec > now2.tv_usec) {
819 			now2.tv_usec += 1000000;
820 			now2.tv_sec--;
821 		}
822 
823 		f = now2.tv_sec - now1.tv_sec +
824 		    (now2.tv_usec - now1.tv_usec) / 100000.0;
825 		tftp_log(LOG_INFO,
826 		    "Download of %jd bytes in %d blocks completed after %0.1f seconds\n",
827 		    (intmax_t)ts.amount, block, f);
828 	}
829 
830 	return;
831 }
832