xref: /freebsd/stand/libsa/tftp.c (revision 53b70c86) 
1 /*	$NetBSD: tftp.c,v 1.4 1997/09/17 16:57:07 drochner Exp $	 */
2 
3 /*
4  * Copyright (c) 1996
5  *	Matthias Drochner.  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 for the NetBSD Project
18  *	by Matthias Drochner.
19  * 4. The name of the author may not be used to endorse or promote products
20  *    derived from this software without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32  */
33 
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36 
37 /*
38  * Simple TFTP implementation for libsa.
39  * Assumes:
40  *  - socket descriptor (int) at open_file->f_devdata
41  *  - server host IP in global rootip
42  * Restrictions:
43  *  - read only
44  *  - lseek only with SEEK_SET or SEEK_CUR
45  *  - no big time differences between transfers (<tftp timeout)
46  */
47 
48 #include <sys/types.h>
49 #include <sys/stat.h>
50 #include <netinet/in.h>
51 #include <netinet/udp.h>
52 #include <netinet/in_systm.h>
53 #include <arpa/tftp.h>
54 
55 #include <string.h>
56 
57 #include "stand.h"
58 #include "net.h"
59 #include "netif.h"
60 
61 #include "tftp.h"
62 
63 struct tftp_handle;
64 struct tftprecv_extra;
65 
66 static ssize_t recvtftp(struct iodesc *, void **, void **, time_t, void *);
67 static int tftp_open(const char *, struct open_file *);
68 static int tftp_close(struct open_file *);
69 static int tftp_parse_oack(struct tftp_handle *, char *, size_t);
70 static int tftp_read(struct open_file *, void *, size_t, size_t *);
71 static off_t tftp_seek(struct open_file *, off_t, int);
72 static int tftp_set_blksize(struct tftp_handle *, const char *);
73 static int tftp_stat(struct open_file *, struct stat *);
74 
75 struct fs_ops tftp_fsops = {
76 	.fs_name = "tftp",
77 	.fo_open = tftp_open,
78 	.fo_close = tftp_close,
79 	.fo_read = tftp_read,
80 	.fo_write = null_write,
81 	.fo_seek = tftp_seek,
82 	.fo_stat = tftp_stat,
83 	.fo_readdir = null_readdir
84 };
85 
86 static int	tftpport = 2000;
87 static int	is_open = 0;
88 
89 /*
90  * The legacy TFTP_BLKSIZE value was SEGSIZE(512).
91  * TFTP_REQUESTED_BLKSIZE of 1428 is (Ethernet MTU, less the TFTP, UDP and
92  * IP header lengths).
93  */
94 #define	TFTP_REQUESTED_BLKSIZE 1428
95 
96 /*
97  * Choose a blksize big enough so we can test with Ethernet
98  * Jumbo frames in the future.
99  */
100 #define	TFTP_MAX_BLKSIZE 9008
101 #define TFTP_TRIES 2
102 
103 struct tftp_handle {
104 	struct iodesc  *iodesc;
105 	int		currblock;	/* contents of lastdata */
106 	int		islastblock:1;	/* flag */
107 	int		tries:4;	/* number of read attempts */
108 	int		validsize;
109 	int		off;
110 	char		*path;	/* saved for re-requests */
111 	unsigned int	tftp_blksize;
112 	unsigned long	tftp_tsize;
113 	void		*pkt;
114 	struct tftphdr	*tftp_hdr;
115 };
116 
117 struct tftprecv_extra {
118 	struct tftp_handle	*tftp_handle;
119 	unsigned short		rtype;		/* Received type */
120 };
121 
122 #define	TFTP_MAX_ERRCODE EOPTNEG
123 static const int tftperrors[TFTP_MAX_ERRCODE + 1] = {
124 	0,			/* ??? */
125 	ENOENT,
126 	EPERM,
127 	ENOSPC,
128 	EINVAL,			/* ??? */
129 	EINVAL,			/* ??? */
130 	EEXIST,
131 	EINVAL,			/* ??? */
132 	EINVAL,			/* Option negotiation failed. */
133 };
134 
135 static int  tftp_getnextblock(struct tftp_handle *h);
136 
137 /* send error message back. */
138 static void
139 tftp_senderr(struct tftp_handle *h, u_short errcode, const char *msg)
140 {
141 	struct {
142 		u_char header[HEADER_SIZE];
143 		struct tftphdr t;
144 		u_char space[63]; /* +1 from t */
145 	} __packed __aligned(4) wbuf;
146 	char *wtail;
147 	int len;
148 
149 	len = strlen(msg);
150 	if (len > sizeof(wbuf.space))
151 		len = sizeof(wbuf.space);
152 
153 	wbuf.t.th_opcode = htons((u_short)ERROR);
154 	wbuf.t.th_code = htons(errcode);
155 
156 	wtail = wbuf.t.th_msg;
157 	bcopy(msg, wtail, len);
158 	wtail[len] = '\0';
159 	wtail += len + 1;
160 
161 	sendudp(h->iodesc, &wbuf.t, wtail - (char *)&wbuf.t);
162 }
163 
164 static void
165 tftp_sendack(struct tftp_handle *h, u_short block)
166 {
167 	struct {
168 		u_char header[HEADER_SIZE];
169 		struct tftphdr  t;
170 	} __packed __aligned(4) wbuf;
171 	char *wtail;
172 
173 	wbuf.t.th_opcode = htons((u_short)ACK);
174 	wtail = (char *)&wbuf.t.th_block;
175 	wbuf.t.th_block = htons(block);
176 	wtail += 2;
177 
178 	sendudp(h->iodesc, &wbuf.t, wtail - (char *)&wbuf.t);
179 }
180 
181 static ssize_t
182 recvtftp(struct iodesc *d, void **pkt, void **payload, time_t tleft,
183     void *recv_extra)
184 {
185 	struct tftprecv_extra *extra;
186 	struct tftp_handle *h;
187 	struct tftphdr *t;
188 	void *ptr = NULL;
189 	ssize_t len;
190 
191 	errno = 0;
192 	extra = recv_extra;
193 	h = extra->tftp_handle;
194 
195 	len = readudp(d, &ptr, (void **)&t, tleft);
196 
197 	if (len < 4) {
198 		free(ptr);
199 		return (-1);
200 	}
201 
202 	extra->rtype = ntohs(t->th_opcode);
203 	switch (ntohs(t->th_opcode)) {
204 	case DATA: {
205 		int got;
206 
207 		if (htons(t->th_block) < (u_short)d->xid) {
208 			/*
209 			 * Apparently our ACK was missed, re-send.
210 			 */
211 			tftp_sendack(h, htons(t->th_block));
212 			free(ptr);
213 			return (-1);
214 		}
215 		if (htons(t->th_block) != (u_short)d->xid) {
216 			/*
217 			 * Packet from the future, drop this.
218 			 */
219 			free(ptr);
220 			return (-1);
221 		}
222 		if (d->xid == 1) {
223 			/*
224 			 * First data packet from new port.
225 			 */
226 			struct udphdr *uh;
227 			uh = (struct udphdr *)t - 1;
228 			d->destport = uh->uh_sport;
229 		}
230 		got = len - (t->th_data - (char *)t);
231 		*pkt = ptr;
232 		*payload = t;
233 		return (got);
234 	}
235 	case ERROR:
236 		if ((unsigned)ntohs(t->th_code) > TFTP_MAX_ERRCODE) {
237 			printf("illegal tftp error %d\n", ntohs(t->th_code));
238 			errno = EIO;
239 		} else {
240 #ifdef TFTP_DEBUG
241 			printf("tftp-error %d\n", ntohs(t->th_code));
242 #endif
243 			errno = tftperrors[ntohs(t->th_code)];
244 		}
245 		free(ptr);
246 		return (-1);
247 	case OACK: {
248 		struct udphdr *uh;
249 		int tftp_oack_len;
250 
251 		/*
252 		 * Unexpected OACK. TFTP transfer already in progress.
253 		 * Drop the pkt.
254 		 */
255 		if (d->xid != 1) {
256 			free(ptr);
257 			return (-1);
258 		}
259 
260 		/*
261 		 * Remember which port this OACK came from, because we need
262 		 * to send the ACK or errors back to it.
263 		 */
264 		uh = (struct udphdr *)t - 1;
265 		d->destport = uh->uh_sport;
266 
267 		/* Parse options ACK-ed by the server. */
268 		tftp_oack_len = len - sizeof(t->th_opcode);
269 		if (tftp_parse_oack(h, t->th_u.tu_stuff, tftp_oack_len) != 0) {
270 			tftp_senderr(h, EOPTNEG, "Malformed OACK");
271 			errno = EIO;
272 			free(ptr);
273 			return (-1);
274 		}
275 		*pkt = ptr;
276 		*payload = t;
277 		return (0);
278 	}
279 	default:
280 #ifdef TFTP_DEBUG
281 		printf("tftp type %d not handled\n", ntohs(t->th_opcode));
282 #endif
283 		free(ptr);
284 		return (-1);
285 	}
286 }
287 
288 /* send request, expect first block (or error) */
289 static int
290 tftp_makereq(struct tftp_handle *h)
291 {
292 	struct {
293 		u_char header[HEADER_SIZE];
294 		struct tftphdr  t;
295 		u_char space[FNAME_SIZE + 6];
296 	} __packed __aligned(4) wbuf;
297 	struct tftprecv_extra recv_extra;
298 	char *wtail;
299 	int l;
300 	ssize_t res;
301 	void *pkt;
302 	struct tftphdr *t;
303 	char *tftp_blksize = NULL;
304 	int blksize_l;
305 
306 	/*
307 	 * Allow overriding default TFTP block size by setting
308 	 * a tftp.blksize environment variable.
309 	 */
310 	if ((tftp_blksize = getenv("tftp.blksize")) != NULL) {
311 		tftp_set_blksize(h, tftp_blksize);
312 	}
313 
314 	wbuf.t.th_opcode = htons((u_short)RRQ);
315 	wtail = wbuf.t.th_stuff;
316 	l = strlen(h->path);
317 #ifdef TFTP_PREPEND_PATH
318 	if (l > FNAME_SIZE - (sizeof(TFTP_PREPEND_PATH) - 1))
319 		return (ENAMETOOLONG);
320 	bcopy(TFTP_PREPEND_PATH, wtail, sizeof(TFTP_PREPEND_PATH) - 1);
321 	wtail += sizeof(TFTP_PREPEND_PATH) - 1;
322 #else
323 	if (l > FNAME_SIZE)
324 		return (ENAMETOOLONG);
325 #endif
326 	bcopy(h->path, wtail, l + 1);
327 	wtail += l + 1;
328 	bcopy("octet", wtail, 6);
329 	wtail += 6;
330 	bcopy("blksize", wtail, 8);
331 	wtail += 8;
332 	blksize_l = sprintf(wtail, "%d", h->tftp_blksize);
333 	wtail += blksize_l + 1;
334 	bcopy("tsize", wtail, 6);
335 	wtail += 6;
336 	bcopy("0", wtail, 2);
337 	wtail += 2;
338 
339 	h->iodesc->myport = htons(tftpport + (getsecs() & 0x3ff));
340 	h->iodesc->destport = htons(IPPORT_TFTP);
341 	h->iodesc->xid = 1;	/* expected block */
342 
343 	h->currblock = 0;
344 	h->islastblock = 0;
345 	h->validsize = 0;
346 
347 	pkt = NULL;
348 	recv_extra.tftp_handle = h;
349 	res = sendrecv(h->iodesc, &sendudp, &wbuf.t, wtail - (char *)&wbuf.t,
350 	    &recvtftp, &pkt, (void **)&t, &recv_extra);
351 	if (res == -1) {
352 		free(pkt);
353 		return (errno);
354 	}
355 
356 	free(h->pkt);
357 	h->pkt = pkt;
358 	h->tftp_hdr = t;
359 
360 	if (recv_extra.rtype == OACK)
361 		return (tftp_getnextblock(h));
362 
363 	/* Server ignored our blksize request, revert to TFTP default. */
364 	h->tftp_blksize = SEGSIZE;
365 
366 	switch (recv_extra.rtype) {
367 		case DATA: {
368 			h->currblock = 1;
369 			h->validsize = res;
370 			h->islastblock = 0;
371 			if (res < h->tftp_blksize) {
372 				h->islastblock = 1;	/* very short file */
373 				tftp_sendack(h, h->currblock);
374 			}
375 			return (0);
376 		}
377 		case ERROR:
378 		default:
379 			return (errno);
380 	}
381 
382 }
383 
384 /* ack block, expect next */
385 static int
386 tftp_getnextblock(struct tftp_handle *h)
387 {
388 	struct {
389 		u_char header[HEADER_SIZE];
390 		struct tftphdr t;
391 	} __packed __aligned(4) wbuf;
392 	struct tftprecv_extra recv_extra;
393 	char *wtail;
394 	int res;
395 	void *pkt;
396 	struct tftphdr *t;
397 
398 	wbuf.t.th_opcode = htons((u_short)ACK);
399 	wtail = (char *)&wbuf.t.th_block;
400 	wbuf.t.th_block = htons((u_short)h->currblock);
401 	wtail += 2;
402 
403 	h->iodesc->xid = h->currblock + 1;	/* expected block */
404 
405 	pkt = NULL;
406 	recv_extra.tftp_handle = h;
407 	res = sendrecv(h->iodesc, &sendudp, &wbuf.t, wtail - (char *)&wbuf.t,
408 	    &recvtftp, &pkt, (void **)&t, &recv_extra);
409 
410 	if (res == -1) {		/* 0 is OK! */
411 		free(pkt);
412 		return (errno);
413 	}
414 
415 	free(h->pkt);
416 	h->pkt = pkt;
417 	h->tftp_hdr = t;
418 	h->currblock++;
419 	h->validsize = res;
420 	if (res < h->tftp_blksize)
421 		h->islastblock = 1;	/* EOF */
422 
423 	if (h->islastblock == 1) {
424 		/* Send an ACK for the last block */
425 		wbuf.t.th_block = htons((u_short)h->currblock);
426 		sendudp(h->iodesc, &wbuf.t, wtail - (char *)&wbuf.t);
427 	}
428 
429 	return (0);
430 }
431 
432 static int
433 tftp_open(const char *path, struct open_file *f)
434 {
435 	struct tftp_handle *tftpfile;
436 	struct iodesc	*io;
437 	int		res;
438 	size_t		pathsize;
439 	const char	*extraslash;
440 
441 	if (netproto != NET_TFTP)
442 		return (EINVAL);
443 
444 	if (f->f_dev->dv_type != DEVT_NET)
445 		return (EINVAL);
446 
447 	if (is_open)
448 		return (EBUSY);
449 
450 	tftpfile = calloc(1, sizeof(*tftpfile));
451 	if (!tftpfile)
452 		return (ENOMEM);
453 
454 	tftpfile->tftp_blksize = TFTP_REQUESTED_BLKSIZE;
455 	tftpfile->iodesc = io = socktodesc(*(int *)(f->f_devdata));
456 	if (io == NULL) {
457 		free(tftpfile);
458 		return (EINVAL);
459 	}
460 
461 	io->destip = rootip;
462 	tftpfile->off = 0;
463 	pathsize = (strlen(rootpath) + 1 + strlen(path) + 1) * sizeof(char);
464 	tftpfile->path = malloc(pathsize);
465 	if (tftpfile->path == NULL) {
466 		free(tftpfile);
467 		return (ENOMEM);
468 	}
469 	if (rootpath[strlen(rootpath) - 1] == '/' || path[0] == '/')
470 		extraslash = "";
471 	else
472 		extraslash = "/";
473 	res = snprintf(tftpfile->path, pathsize, "%s%s%s",
474 	    rootpath, extraslash, path);
475 	if (res < 0 || res > pathsize) {
476 		free(tftpfile->path);
477 		free(tftpfile);
478 		return (ENOMEM);
479 	}
480 
481 	res = tftp_makereq(tftpfile);
482 
483 	if (res) {
484 		free(tftpfile->path);
485 		free(tftpfile->pkt);
486 		free(tftpfile);
487 		return (res);
488 	}
489 	f->f_fsdata = tftpfile;
490 	is_open = 1;
491 	return (0);
492 }
493 
494 static int
495 tftp_read(struct open_file *f, void *addr, size_t size,
496     size_t *resid /* out */)
497 {
498 	struct tftp_handle *tftpfile;
499 	size_t res;
500 	int rc;
501 
502 	rc = 0;
503 	res = size;
504 	tftpfile = f->f_fsdata;
505 
506 	/* Make sure we will not read past file end */
507 	if (tftpfile->tftp_tsize > 0 &&
508 	    tftpfile->off + size > tftpfile->tftp_tsize) {
509 		size = tftpfile->tftp_tsize - tftpfile->off;
510 	}
511 
512 	while (size > 0) {
513 		int needblock, count;
514 
515 		twiddle(32);
516 
517 		needblock = tftpfile->off / tftpfile->tftp_blksize + 1;
518 
519 		if (tftpfile->currblock > needblock) {	/* seek backwards */
520 			tftp_senderr(tftpfile, 0, "No error: read aborted");
521 			rc = tftp_makereq(tftpfile);
522 			if (rc != 0)
523 				break;
524 		}
525 
526 		while (tftpfile->currblock < needblock) {
527 
528 			rc = tftp_getnextblock(tftpfile);
529 			if (rc) {	/* no answer */
530 #ifdef TFTP_DEBUG
531 				printf("tftp: read error\n");
532 #endif
533 				if (tftpfile->tries > TFTP_TRIES) {
534 					return (rc);
535 				} else {
536 					tftpfile->tries++;
537 					tftp_makereq(tftpfile);
538 				}
539 			}
540 			if (tftpfile->islastblock)
541 				break;
542 		}
543 
544 		if (tftpfile->currblock == needblock) {
545 			int offinblock, inbuffer;
546 
547 			offinblock = tftpfile->off % tftpfile->tftp_blksize;
548 
549 			inbuffer = tftpfile->validsize - offinblock;
550 			if (inbuffer < 0) {
551 #ifdef TFTP_DEBUG
552 				printf("tftp: invalid offset %d\n",
553 				    tftpfile->off);
554 #endif
555 				return (EINVAL);
556 			}
557 			count = (size < inbuffer ? size : inbuffer);
558 			bcopy(tftpfile->tftp_hdr->th_data + offinblock,
559 			    addr, count);
560 
561 			addr = (char *)addr + count;
562 			tftpfile->off += count;
563 			size -= count;
564 			res -= count;
565 
566 			if ((tftpfile->islastblock) && (count == inbuffer))
567 				break;	/* EOF */
568 		} else {
569 #ifdef TFTP_DEBUG
570 			printf("tftp: block %d not found\n", needblock);
571 #endif
572 			return (EINVAL);
573 		}
574 
575 	}
576 
577 	if (resid != NULL)
578 		*resid = res;
579 	return (rc);
580 }
581 
582 static int
583 tftp_close(struct open_file *f)
584 {
585 	struct tftp_handle *tftpfile;
586 	tftpfile = f->f_fsdata;
587 
588 	/* let it time out ... */
589 
590 	if (tftpfile) {
591 		free(tftpfile->path);
592 		free(tftpfile->pkt);
593 		free(tftpfile);
594 	}
595 	is_open = 0;
596 	return (0);
597 }
598 
599 static int
600 tftp_stat(struct open_file *f, struct stat *sb)
601 {
602 	struct tftp_handle *tftpfile;
603 	tftpfile = f->f_fsdata;
604 
605 	sb->st_mode = 0444 | S_IFREG;
606 	sb->st_nlink = 1;
607 	sb->st_uid = 0;
608 	sb->st_gid = 0;
609 	sb->st_size = tftpfile->tftp_tsize;
610 	return (0);
611 }
612 
613 static off_t
614 tftp_seek(struct open_file *f, off_t offset, int where)
615 {
616 	struct tftp_handle *tftpfile;
617 	tftpfile = f->f_fsdata;
618 
619 	switch (where) {
620 	case SEEK_SET:
621 		tftpfile->off = offset;
622 		break;
623 	case SEEK_CUR:
624 		tftpfile->off += offset;
625 		break;
626 	default:
627 		errno = EOFFSET;
628 		return (-1);
629 	}
630 	return (tftpfile->off);
631 }
632 
633 static int
634 tftp_set_blksize(struct tftp_handle *h, const char *str)
635 {
636 	char *endptr;
637 	int new_blksize;
638 	int ret = 0;
639 
640 	if (h == NULL || str == NULL)
641 		return (ret);
642 
643 	new_blksize =
644 	    (unsigned int)strtol(str, &endptr, 0);
645 
646 	/*
647 	 * Only accept blksize value if it is numeric.
648 	 * RFC2348 specifies that acceptable values are 8-65464.
649 	 * Let's choose a limit less than MAXRSPACE.
650 	 */
651 	if (*endptr == '\0' && new_blksize >= 8 &&
652 	    new_blksize <= TFTP_MAX_BLKSIZE) {
653 		h->tftp_blksize = new_blksize;
654 		ret = 1;
655 	}
656 
657 	return (ret);
658 }
659 
660 /*
661  * In RFC2347, the TFTP Option Acknowledgement package (OACK)
662  * is used to acknowledge a client's option negotiation request.
663  * The format of an OACK packet is:
664  *    +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
665  *    |  opc  |  opt1  | 0 | value1 | 0 |  optN  | 0 | valueN | 0 |
666  *    +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
667  *
668  *    opc
669  *       The opcode field contains a 6, for Option Acknowledgment.
670  *
671  *    opt1
672  *       The first option acknowledgment, copied from the original
673  *       request.
674  *
675  *    value1
676  *       The acknowledged value associated with the first option.  If
677  *       and how this value may differ from the original request is
678  *       detailed in the specification for the option.
679  *
680  *    optN, valueN
681  *       The final option/value acknowledgment pair.
682  */
683 static int
684 tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len)
685 {
686 	/*
687 	 *  We parse the OACK strings into an array
688 	 *  of name-value pairs.
689 	 */
690 	char *tftp_options[128] = { 0 };
691 	char *val = buf;
692 	int i = 0;
693 	int option_idx = 0;
694 	int blksize_is_set = 0;
695 	int tsize = 0;
696 
697 	unsigned int orig_blksize;
698 
699 	while (option_idx < 128 && i < len) {
700 		if (buf[i] == '\0') {
701 			if (&buf[i] > val) {
702 				tftp_options[option_idx] = val;
703 				val = &buf[i] + 1;
704 				++option_idx;
705 			}
706 		}
707 		++i;
708 	}
709 
710 	/* Save the block size we requested for sanity check later. */
711 	orig_blksize = h->tftp_blksize;
712 
713 	/*
714 	 * Parse individual TFTP options.
715 	 *    * "blksize" is specified in RFC2348.
716 	 *    * "tsize" is specified in RFC2349.
717 	 */
718 	for (i = 0; i < option_idx; i += 2) {
719 		if (strcasecmp(tftp_options[i], "blksize") == 0) {
720 			if (i + 1 < option_idx)
721 				blksize_is_set =
722 				    tftp_set_blksize(h, tftp_options[i + 1]);
723 		} else if (strcasecmp(tftp_options[i], "tsize") == 0) {
724 			if (i + 1 < option_idx)
725 				tsize = strtol(tftp_options[i + 1], NULL, 10);
726 			if (tsize != 0)
727 				h->tftp_tsize = tsize;
728 		} else {
729 			/*
730 			 * Do not allow any options we did not expect to be
731 			 * ACKed.
732 			 */
733 			printf("unexpected tftp option '%s'\n",
734 			    tftp_options[i]);
735 			return (-1);
736 		}
737 	}
738 
739 	if (!blksize_is_set) {
740 		/*
741 		 * If TFTP blksize was not set, try defaulting
742 		 * to the legacy TFTP blksize of SEGSIZE(512)
743 		 */
744 		h->tftp_blksize = SEGSIZE;
745 	} else if (h->tftp_blksize > orig_blksize) {
746 		/*
747 		 * Server should not be proposing block sizes that
748 		 * exceed what we said we can handle.
749 		 */
750 		printf("unexpected blksize %u\n", h->tftp_blksize);
751 		return (-1);
752 	}
753 
754 #ifdef TFTP_DEBUG
755 	printf("tftp_blksize: %u\n", h->tftp_blksize);
756 	printf("tftp_tsize: %lu\n", h->tftp_tsize);
757 #endif
758 	return (0);
759 }
760