xref: /illumos-gate/usr/src/boot/libsa/tftp.c (revision 22028508)
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 
36 /*
37  * Simple TFTP implementation for libsa.
38  * Assumes:
39  *  - socket descriptor (int) at dev->d_opendata, dev stored at
40  *	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 
102 struct tftp_handle {
103 	struct iodesc  *iodesc;
104 	int		currblock;	/* contents of lastdata */
105 	int		islastblock;	/* flag */
106 	int		validsize;
107 	int		off;
108 	char		*path;	/* saved for re-requests */
109 	unsigned int	tftp_blksize;
110 	unsigned long	tftp_tsize;
111 	void		*pkt;
112 	struct tftphdr	*tftp_hdr;
113 };
114 
115 struct tftprecv_extra {
116 	struct tftp_handle	*tftp_handle;
117 	unsigned short		rtype;		/* Received type */
118 };
119 
120 #define	TFTP_MAX_ERRCODE EOPTNEG
121 static const int tftperrors[TFTP_MAX_ERRCODE + 1] = {
122 	0,			/* ??? */
123 	ENOENT,
124 	EPERM,
125 	ENOSPC,
126 	EINVAL,			/* ??? */
127 	EINVAL,			/* ??? */
128 	EEXIST,
129 	EINVAL,			/* ??? */
130 	EINVAL,			/* Option negotiation failed. */
131 };
132 
133 static int  tftp_getnextblock(struct tftp_handle *h);
134 
135 /* send error message back. */
136 static void
tftp_senderr(struct tftp_handle * h,ushort_t errcode,const char * msg)137 tftp_senderr(struct tftp_handle *h, ushort_t errcode, const char *msg)
138 {
139 	struct {
140 		uchar_t header[HEADER_SIZE];
141 		struct tftphdr t;
142 		uchar_t space[63]; /* +1 from t */
143 	} __packed __aligned(4) wbuf;
144 	char *wtail;
145 	int len;
146 
147 	len = strlen(msg);
148 	if (len > sizeof (wbuf.space))
149 		len = sizeof (wbuf.space);
150 
151 	wbuf.t.th_opcode = htons((ushort_t)ERROR);
152 	wbuf.t.th_code = htons(errcode);
153 
154 	wtail = wbuf.t.th_msg;
155 	bcopy(msg, wtail, len);
156 	wtail[len] = '\0';
157 	wtail += len + 1;
158 
159 	sendudp(h->iodesc, &wbuf.t, wtail - (char *)&wbuf.t);
160 }
161 
162 static void
tftp_sendack(struct tftp_handle * h,ushort_t block)163 tftp_sendack(struct tftp_handle *h, ushort_t block)
164 {
165 	struct {
166 		uchar_t header[HEADER_SIZE];
167 		struct tftphdr  t;
168 	} __packed __aligned(4) wbuf;
169 	char *wtail;
170 
171 	wbuf.t.th_opcode = htons((ushort_t)ACK);
172 	wtail = (char *)&wbuf.t.th_block;
173 	wbuf.t.th_block = htons(block);
174 	wtail += 2;
175 
176 	sendudp(h->iodesc, &wbuf.t, wtail - (char *)&wbuf.t);
177 }
178 
179 static ssize_t
recvtftp(struct iodesc * d,void ** pkt,void ** payload,time_t tleft,void * recv_extra)180 recvtftp(struct iodesc *d, void **pkt, void **payload, time_t tleft,
181     void *recv_extra)
182 {
183 	struct tftprecv_extra *extra;
184 	struct tftp_handle *h;
185 	struct tftphdr *t;
186 	void *ptr = NULL;
187 	ssize_t len;
188 
189 	errno = 0;
190 	extra = recv_extra;
191 	h = extra->tftp_handle;
192 
193 	len = readudp(d, &ptr, (void **)&t, tleft);
194 
195 	if (len < 4) {
196 		free(ptr);
197 		return (-1);
198 	}
199 
200 	extra->rtype = ntohs(t->th_opcode);
201 	switch (ntohs(t->th_opcode)) {
202 	case DATA: {
203 		int got;
204 
205 		if (htons(t->th_block) < (ushort_t)d->xid) {
206 			/*
207 			 * Apparently our ACK was missed, re-send.
208 			 */
209 			tftp_sendack(h, htons(t->th_block));
210 			free(ptr);
211 			return (-1);
212 		}
213 		if (htons(t->th_block) != (ushort_t)d->xid) {
214 			/*
215 			 * Packet from the future, drop this.
216 			 */
217 			free(ptr);
218 			return (-1);
219 		}
220 		if (d->xid == 1) {
221 			/*
222 			 * First data packet from new port.
223 			 */
224 			struct udphdr *uh;
225 			uh = (struct udphdr *)t - 1;
226 			d->destport = uh->uh_sport;
227 		}
228 		got = len - (t->th_data - (char *)t);
229 		*pkt = ptr;
230 		*payload = t;
231 		return (got);
232 	}
233 	case ERROR:
234 		if ((unsigned)ntohs(t->th_code) > TFTP_MAX_ERRCODE) {
235 			printf("illegal tftp error %d\n", ntohs(t->th_code));
236 			errno = EIO;
237 		} else {
238 #ifdef TFTP_DEBUG
239 			printf("tftp-error %d\n", ntohs(t->th_code));
240 #endif
241 			errno = tftperrors[ntohs(t->th_code)];
242 		}
243 		free(ptr);
244 		return (-1);
245 	case OACK: {
246 		struct udphdr *uh;
247 		int tftp_oack_len;
248 
249 		/*
250 		 * Unexpected OACK. TFTP transfer already in progress.
251 		 * Drop the pkt.
252 		 */
253 		if (d->xid != 1) {
254 			free(ptr);
255 			return (-1);
256 		}
257 
258 		/*
259 		 * Remember which port this OACK came from, because we need
260 		 * to send the ACK or errors back to it.
261 		 */
262 		uh = (struct udphdr *)t - 1;
263 		d->destport = uh->uh_sport;
264 
265 		/* Parse options ACK-ed by the server. */
266 		tftp_oack_len = len - sizeof (t->th_opcode);
267 		if (tftp_parse_oack(h, t->th_u.tu_stuff, tftp_oack_len) != 0) {
268 			tftp_senderr(h, EOPTNEG, "Malformed OACK");
269 			errno = EIO;
270 			free(ptr);
271 			return (-1);
272 		}
273 		*pkt = ptr;
274 		*payload = t;
275 		return (0);
276 	}
277 	default:
278 #ifdef TFTP_DEBUG
279 		printf("tftp type %d not handled\n", ntohs(t->th_opcode));
280 #endif
281 		free(ptr);
282 		return (-1);
283 	}
284 }
285 
286 /* send request, expect first block (or error) */
287 static int
tftp_makereq(struct tftp_handle * h)288 tftp_makereq(struct tftp_handle *h)
289 {
290 	struct {
291 		uchar_t header[HEADER_SIZE];
292 		struct tftphdr  t;
293 		uchar_t space[FNAME_SIZE + 6];
294 	} __packed __aligned(4) wbuf;
295 	struct tftprecv_extra recv_extra;
296 	char *wtail;
297 	int l;
298 	ssize_t res;
299 	void *pkt;
300 	struct tftphdr *t;
301 	char *tftp_blksize = NULL;
302 	int blksize_l;
303 
304 	/*
305 	 * Allow overriding default TFTP block size by setting
306 	 * a tftp.blksize environment variable.
307 	 */
308 	if ((tftp_blksize = getenv("tftp.blksize")) != NULL) {
309 		tftp_set_blksize(h, tftp_blksize);
310 	}
311 
312 	wbuf.t.th_opcode = htons((ushort_t)RRQ);
313 	wtail = wbuf.t.th_stuff;
314 	l = strlen(h->path);
315 #ifdef TFTP_PREPEND_PATH
316 	if (l > FNAME_SIZE - (sizeof (TFTP_PREPEND_PATH) - 1))
317 		return (ENAMETOOLONG);
318 	bcopy(TFTP_PREPEND_PATH, wtail, sizeof (TFTP_PREPEND_PATH) - 1);
319 	wtail += sizeof (TFTP_PREPEND_PATH) - 1;
320 #else
321 	if (l > FNAME_SIZE)
322 		return (ENAMETOOLONG);
323 #endif
324 	bcopy(h->path, wtail, l + 1);
325 	wtail += l + 1;
326 	bcopy("octet", wtail, 6);
327 	wtail += 6;
328 	bcopy("blksize", wtail, 8);
329 	wtail += 8;
330 	blksize_l = sprintf(wtail, "%d", h->tftp_blksize);
331 	wtail += blksize_l + 1;
332 	bcopy("tsize", wtail, 6);
333 	wtail += 6;
334 	bcopy("0", wtail, 2);
335 	wtail += 2;
336 
337 	h->iodesc->myport = htons(tftpport + (getsecs() & 0x3ff));
338 	h->iodesc->destport = htons(IPPORT_TFTP);
339 	h->iodesc->xid = 1;	/* expected block */
340 
341 	h->currblock = 0;
342 	h->islastblock = 0;
343 	h->validsize = 0;
344 
345 	pkt = NULL;
346 	recv_extra.tftp_handle = h;
347 	res = sendrecv(h->iodesc, &sendudp, &wbuf.t, wtail - (char *)&wbuf.t,
348 	    &recvtftp, &pkt, (void **)&t, &recv_extra);
349 	if (res == -1) {
350 		free(pkt);
351 		return (errno);
352 	}
353 
354 	free(h->pkt);
355 	h->pkt = pkt;
356 	h->tftp_hdr = t;
357 
358 	if (recv_extra.rtype == OACK)
359 		return (tftp_getnextblock(h));
360 
361 	/* Server ignored our blksize request, revert to TFTP default. */
362 	h->tftp_blksize = SEGSIZE;
363 
364 	switch (recv_extra.rtype) {
365 		case DATA: {
366 			h->currblock = 1;
367 			h->validsize = res;
368 			h->islastblock = 0;
369 			if (res < h->tftp_blksize) {
370 				h->islastblock = 1;	/* very short file */
371 				tftp_sendack(h, h->currblock);
372 			}
373 			return (0);
374 		}
375 		case ERROR:
376 		default:
377 			return (errno);
378 	}
379 
380 }
381 
382 /* ack block, expect next */
383 static int
tftp_getnextblock(struct tftp_handle * h)384 tftp_getnextblock(struct tftp_handle *h)
385 {
386 	struct {
387 		uchar_t header[HEADER_SIZE];
388 		struct tftphdr t;
389 	} __packed __aligned(4) wbuf;
390 	struct tftprecv_extra recv_extra;
391 	char *wtail;
392 	int res;
393 	void *pkt;
394 	struct tftphdr *t;
395 
396 	wbuf.t.th_opcode = htons((ushort_t)ACK);
397 	wtail = (char *)&wbuf.t.th_block;
398 	wbuf.t.th_block = htons((ushort_t)h->currblock);
399 	wtail += 2;
400 
401 	h->iodesc->xid = h->currblock + 1;	/* expected block */
402 
403 	pkt = NULL;
404 	recv_extra.tftp_handle = h;
405 	res = sendrecv(h->iodesc, &sendudp, &wbuf.t, wtail - (char *)&wbuf.t,
406 	    &recvtftp, &pkt, (void **)&t, &recv_extra);
407 
408 	if (res == -1) {		/* 0 is OK! */
409 		free(pkt);
410 		return (errno);
411 	}
412 
413 	free(h->pkt);
414 	h->pkt = pkt;
415 	h->tftp_hdr = t;
416 	h->currblock++;
417 	h->validsize = res;
418 	if (res < h->tftp_blksize)
419 		h->islastblock = 1;	/* EOF */
420 
421 	if (h->islastblock == 1) {
422 		/* Send an ACK for the last block */
423 		wbuf.t.th_block = htons((ushort_t)h->currblock);
424 		sendudp(h->iodesc, &wbuf.t, wtail - (char *)&wbuf.t);
425 	}
426 
427 	return (0);
428 }
429 
430 static int
tftp_open(const char * path,struct open_file * f)431 tftp_open(const char *path, struct open_file *f)
432 {
433 	struct devdesc *dev;
434 	struct tftp_handle *tftpfile;
435 	struct iodesc	*io;
436 	int		res;
437 	size_t		pathsize;
438 	const char	*extraslash;
439 
440 	if (netproto != NET_TFTP)
441 		return (EINVAL);
442 
443 	if (f->f_dev->dv_type != DEVT_NET)
444 		return (EINVAL);
445 
446 	if (is_open)
447 		return (EBUSY);
448 
449 	tftpfile = calloc(1, sizeof (*tftpfile));
450 	if (!tftpfile)
451 		return (ENOMEM);
452 
453 	tftpfile->tftp_blksize = TFTP_REQUESTED_BLKSIZE;
454 	dev = f->f_devdata;
455 	tftpfile->iodesc = io = socktodesc(*(int *)(dev->d_opendata));
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
tftp_read(struct open_file * f,void * addr,size_t size,size_t * resid)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 				return (rc);
534 			}
535 			if (tftpfile->islastblock)
536 				break;
537 		}
538 
539 		if (tftpfile->currblock == needblock) {
540 			int offinblock, inbuffer;
541 
542 			offinblock = tftpfile->off % tftpfile->tftp_blksize;
543 
544 			inbuffer = tftpfile->validsize - offinblock;
545 			if (inbuffer < 0) {
546 #ifdef TFTP_DEBUG
547 				printf("tftp: invalid offset %d\n",
548 				    tftpfile->off);
549 #endif
550 				return (EINVAL);
551 			}
552 			count = (size < inbuffer ? size : inbuffer);
553 			bcopy(tftpfile->tftp_hdr->th_data + offinblock,
554 			    addr, count);
555 
556 			addr = (char *)addr + count;
557 			tftpfile->off += count;
558 			size -= count;
559 			res -= count;
560 
561 			if ((tftpfile->islastblock) && (count == inbuffer))
562 				break;	/* EOF */
563 		} else {
564 #ifdef TFTP_DEBUG
565 			printf("tftp: block %d not found\n", needblock);
566 #endif
567 			return (EINVAL);
568 		}
569 
570 	}
571 
572 	if (resid != NULL)
573 		*resid = res;
574 	return (rc);
575 }
576 
577 static int
tftp_close(struct open_file * f)578 tftp_close(struct open_file *f)
579 {
580 	struct tftp_handle *tftpfile;
581 	tftpfile = f->f_fsdata;
582 
583 	/* let it time out ... */
584 
585 	if (tftpfile) {
586 		free(tftpfile->path);
587 		free(tftpfile->pkt);
588 		free(tftpfile);
589 	}
590 	is_open = 0;
591 	return (0);
592 }
593 
594 static int
tftp_stat(struct open_file * f,struct stat * sb)595 tftp_stat(struct open_file *f, struct stat *sb)
596 {
597 	struct tftp_handle *tftpfile;
598 	tftpfile = f->f_fsdata;
599 
600 	sb->st_mode = 0444 | S_IFREG;
601 	sb->st_nlink = 1;
602 	sb->st_uid = 0;
603 	sb->st_gid = 0;
604 	sb->st_size = tftpfile->tftp_tsize;
605 	return (0);
606 }
607 
608 static off_t
tftp_seek(struct open_file * f,off_t offset,int where)609 tftp_seek(struct open_file *f, off_t offset, int where)
610 {
611 	struct tftp_handle *tftpfile;
612 	tftpfile = f->f_fsdata;
613 
614 	switch (where) {
615 	case SEEK_SET:
616 		tftpfile->off = offset;
617 		break;
618 	case SEEK_CUR:
619 		tftpfile->off += offset;
620 		break;
621 	default:
622 		errno = EOFFSET;
623 		return (-1);
624 	}
625 	return (tftpfile->off);
626 }
627 
628 static int
tftp_set_blksize(struct tftp_handle * h,const char * str)629 tftp_set_blksize(struct tftp_handle *h, const char *str)
630 {
631 	char *endptr;
632 	int new_blksize;
633 	int ret = 0;
634 
635 	if (h == NULL || str == NULL)
636 		return (ret);
637 
638 	new_blksize =
639 	    (unsigned int)strtol(str, &endptr, 0);
640 
641 	/*
642 	 * Only accept blksize value if it is numeric.
643 	 * RFC2348 specifies that acceptable values are 8-65464.
644 	 * Let's choose a limit less than MAXRSPACE.
645 	 */
646 	if (*endptr == '\0' && new_blksize >= 8 &&
647 	    new_blksize <= TFTP_MAX_BLKSIZE) {
648 		h->tftp_blksize = new_blksize;
649 		ret = 1;
650 	}
651 
652 	return (ret);
653 }
654 
655 /*
656  * In RFC2347, the TFTP Option Acknowledgement package (OACK)
657  * is used to acknowledge a client's option negotiation request.
658  * The format of an OACK packet is:
659  *    +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
660  *    |  opc  |  opt1  | 0 | value1 | 0 |  optN  | 0 | valueN | 0 |
661  *    +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
662  *
663  *    opc
664  *       The opcode field contains a 6, for Option Acknowledgment.
665  *
666  *    opt1
667  *       The first option acknowledgment, copied from the original
668  *       request.
669  *
670  *    value1
671  *       The acknowledged value associated with the first option.  If
672  *       and how this value may differ from the original request is
673  *       detailed in the specification for the option.
674  *
675  *    optN, valueN
676  *       The final option/value acknowledgment pair.
677  */
678 static int
tftp_parse_oack(struct tftp_handle * h,char * buf,size_t len)679 tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len)
680 {
681 	/*
682 	 *  We parse the OACK strings into an array
683 	 *  of name-value pairs.
684 	 */
685 	char *tftp_options[128] = { 0 };
686 	char *val = buf;
687 	int i = 0;
688 	int option_idx = 0;
689 	int blksize_is_set = 0;
690 	int tsize = 0;
691 
692 	unsigned int orig_blksize;
693 
694 	while (option_idx < 128 && i < len) {
695 		if (buf[i] == '\0') {
696 			if (&buf[i] > val) {
697 				tftp_options[option_idx] = val;
698 				val = &buf[i] + 1;
699 				++option_idx;
700 			}
701 		}
702 		++i;
703 	}
704 
705 	/* Save the block size we requested for sanity check later. */
706 	orig_blksize = h->tftp_blksize;
707 
708 	/*
709 	 * Parse individual TFTP options.
710 	 *    * "blksize" is specified in RFC2348.
711 	 *    * "tsize" is specified in RFC2349.
712 	 */
713 	for (i = 0; i < option_idx; i += 2) {
714 		if (strcasecmp(tftp_options[i], "blksize") == 0) {
715 			if (i + 1 < option_idx)
716 				blksize_is_set =
717 				    tftp_set_blksize(h, tftp_options[i + 1]);
718 		} else if (strcasecmp(tftp_options[i], "tsize") == 0) {
719 			if (i + 1 < option_idx)
720 				tsize = strtol(tftp_options[i + 1], NULL, 10);
721 			if (tsize != 0)
722 				h->tftp_tsize = tsize;
723 		} else {
724 			/*
725 			 * Do not allow any options we did not expect to be
726 			 * ACKed.
727 			 */
728 			printf("unexpected tftp option '%s'\n",
729 			    tftp_options[i]);
730 			return (-1);
731 		}
732 	}
733 
734 	if (!blksize_is_set) {
735 		/*
736 		 * If TFTP blksize was not set, try defaulting
737 		 * to the legacy TFTP blksize of SEGSIZE(512)
738 		 */
739 		h->tftp_blksize = SEGSIZE;
740 	} else if (h->tftp_blksize > orig_blksize) {
741 		/*
742 		 * Server should not be proposing block sizes that
743 		 * exceed what we said we can handle.
744 		 */
745 		printf("unexpected blksize %u\n", h->tftp_blksize);
746 		return (-1);
747 	}
748 
749 #ifdef TFTP_DEBUG
750 	printf("tftp_blksize: %u\n", h->tftp_blksize);
751 	printf("tftp_tsize: %lu\n", h->tftp_tsize);
752 #endif
753 	return (0);
754 }
755