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 <bootstrap.h>
58 #include "stand.h"
59 #include "net.h"
60 #include "netif.h"
61
62 #include "tftp.h"
63
64 struct tftp_handle;
65 struct tftprecv_extra;
66
67 static ssize_t recvtftp(struct iodesc *, void **, void **, time_t, void *);
68 static int tftp_open(const char *, struct open_file *);
69 static int tftp_close(struct open_file *);
70 static int tftp_parse_oack(struct tftp_handle *, char *, size_t);
71 static int tftp_read(struct open_file *, void *, size_t, size_t *);
72 static off_t tftp_seek(struct open_file *, off_t, int);
73 static int tftp_set_blksize(struct tftp_handle *, const char *);
74 static int tftp_stat(struct open_file *, struct stat *);
75 static int tftp_preload(struct open_file *);
76
77 struct fs_ops tftp_fsops = {
78 .fs_name = "tftp",
79 .fo_open = tftp_open,
80 .fo_close = tftp_close,
81 .fo_read = tftp_read,
82 .fo_write = null_write,
83 .fo_seek = tftp_seek,
84 .fo_stat = tftp_stat,
85 .fo_preload = tftp_preload,
86 .fo_readdir = null_readdir
87 };
88
89 static int tftpport = 2000;
90 static int is_open = 0;
91
92 /*
93 * The legacy TFTP_BLKSIZE value was SEGSIZE(512).
94 * TFTP_REQUESTED_BLKSIZE of 1428 is (Ethernet MTU, less the TFTP, UDP and
95 * IP header lengths).
96 */
97 #define TFTP_REQUESTED_BLKSIZE 1428
98
99 /*
100 * Choose a blksize big enough so we can test with Ethernet
101 * Jumbo frames in the future.
102 */
103 #define TFTP_MAX_BLKSIZE 9008
104 #define TFTP_TRIES 2
105
106 struct tftp_handle {
107 struct iodesc *iodesc;
108 int currblock; /* contents of lastdata */
109 int islastblock:1; /* flag */
110 int tries:4; /* number of read attempts */
111 int validsize;
112 int off;
113 char *path; /* saved for re-requests */
114 unsigned int tftp_blksize;
115 unsigned long tftp_tsize;
116 void *pkt;
117 struct tftphdr *tftp_hdr;
118 char *tftp_cache;
119 bool lastacksent;
120 };
121
122 struct tftprecv_extra {
123 struct tftp_handle *tftp_handle;
124 unsigned short rtype; /* Received type */
125 };
126
127 #define TFTP_MAX_ERRCODE EOPTNEG
128 static const int tftperrors[TFTP_MAX_ERRCODE + 1] = {
129 0, /* NAK */
130 ENOENT,
131 EPERM,
132 ENOSPC,
133 EINVAL, /* ??? */
134 EINVAL, /* ??? */
135 EEXIST,
136 EINVAL, /* ??? */
137 EINVAL, /* Option negotiation failed. */
138 };
139
140 static int tftp_getnextblock(struct tftp_handle *h);
141
142 /* send error message back. */
143 static void
tftp_senderr(struct tftp_handle * h,u_short errcode,const char * msg)144 tftp_senderr(struct tftp_handle *h, u_short errcode, const char *msg)
145 {
146 struct {
147 u_char header[HEADER_SIZE];
148 struct tftphdr t;
149 u_char space[63]; /* +1 from t */
150 } __packed __aligned(4) wbuf;
151 char *wtail;
152 int len;
153
154 len = strlen(msg);
155 if (len > sizeof(wbuf.space))
156 len = sizeof(wbuf.space);
157
158 wbuf.t.th_opcode = htons((u_short)ERROR);
159 wbuf.t.th_code = htons(errcode);
160
161 wtail = wbuf.t.th_msg;
162 bcopy(msg, wtail, len);
163 wtail[len] = '\0';
164 wtail += len + 1;
165
166 sendudp(h->iodesc, &wbuf.t, wtail - (char *)&wbuf.t);
167 }
168
169 static void
tftp_sendack(struct tftp_handle * h,u_short block)170 tftp_sendack(struct tftp_handle *h, u_short block)
171 {
172 struct {
173 u_char header[HEADER_SIZE];
174 struct tftphdr t;
175 } __packed __aligned(4) wbuf;
176 char *wtail;
177
178 wbuf.t.th_opcode = htons((u_short)ACK);
179 wtail = (char *)&wbuf.t.th_block;
180 wbuf.t.th_block = htons(block);
181 wtail += 2;
182
183 sendudp(h->iodesc, &wbuf.t, wtail - (char *)&wbuf.t);
184 }
185
186 static ssize_t
recvtftp(struct iodesc * d,void ** pkt,void ** payload,time_t tleft,void * recv_extra)187 recvtftp(struct iodesc *d, void **pkt, void **payload, time_t tleft,
188 void *recv_extra)
189 {
190 struct tftprecv_extra *extra;
191 struct tftp_handle *h;
192 struct tftphdr *t;
193 void *ptr = NULL;
194 ssize_t len;
195 int tftp_error;
196
197 errno = 0;
198 extra = recv_extra;
199 h = extra->tftp_handle;
200
201 len = readudp(d, &ptr, (void **)&t, tleft);
202
203 if (len < 4) {
204 free(ptr);
205 return (-1);
206 }
207
208 extra->rtype = ntohs(t->th_opcode);
209 switch (ntohs(t->th_opcode)) {
210 case DATA: {
211 int got;
212
213 if (htons(t->th_block) < (u_short)d->xid) {
214 /*
215 * Apparently our ACK was missed, re-send.
216 */
217 tftp_sendack(h, htons(t->th_block));
218 free(ptr);
219 return (-1);
220 }
221 if (htons(t->th_block) != (u_short)d->xid) {
222 /*
223 * Packet from the future, drop this.
224 */
225 free(ptr);
226 return (-1);
227 }
228 if (d->xid == 1) {
229 /*
230 * First data packet from new port.
231 */
232 struct udphdr *uh;
233 uh = (struct udphdr *)t - 1;
234 d->destport = uh->uh_sport;
235 }
236 got = len - (t->th_data - (char *)t);
237 *pkt = ptr;
238 *payload = t;
239 return (got);
240 }
241 case ERROR:
242 tftp_error = ntohs(t->th_code);
243 if ((unsigned)tftp_error > TFTP_MAX_ERRCODE) {
244 printf("illegal tftp error %d\n", tftp_error);
245 errno = EIO;
246 } else {
247 #ifdef TFTP_DEBUG
248 printf("tftp-error %d\n", tftp_error);
249 #endif
250 errno = tftperrors[tftp_error];
251 }
252 free(ptr);
253 /* If we got a NAK return 0, it's usually a directory */
254 if (tftp_error == 0)
255 return (0);
256 return (-1);
257 case OACK: {
258 struct udphdr *uh;
259 int tftp_oack_len;
260
261 /*
262 * Unexpected OACK. TFTP transfer already in progress.
263 * Drop the pkt.
264 */
265 if (d->xid != 1) {
266 free(ptr);
267 return (-1);
268 }
269
270 /*
271 * Remember which port this OACK came from, because we need
272 * to send the ACK or errors back to it.
273 */
274 uh = (struct udphdr *)t - 1;
275 d->destport = uh->uh_sport;
276
277 /* Parse options ACK-ed by the server. */
278 tftp_oack_len = len - sizeof(t->th_opcode);
279 if (tftp_parse_oack(h, t->th_u.tu_stuff, tftp_oack_len) != 0) {
280 tftp_senderr(h, EOPTNEG, "Malformed OACK");
281 errno = EIO;
282 free(ptr);
283 return (-1);
284 }
285 *pkt = ptr;
286 *payload = t;
287 return (0);
288 }
289 default:
290 #ifdef TFTP_DEBUG
291 printf("tftp type %d not handled\n", ntohs(t->th_opcode));
292 #endif
293 free(ptr);
294 return (-1);
295 }
296 }
297
298 /* send request, expect first block (or error) */
299 static int
tftp_makereq(struct tftp_handle * h)300 tftp_makereq(struct tftp_handle *h)
301 {
302 struct {
303 u_char header[HEADER_SIZE];
304 struct tftphdr t;
305 u_char space[FNAME_SIZE + 6];
306 } __packed __aligned(4) wbuf;
307 struct tftprecv_extra recv_extra;
308 char *wtail;
309 int l;
310 ssize_t res;
311 void *pkt;
312 struct tftphdr *t;
313 char *tftp_blksize = NULL;
314 int blksize_l;
315
316 /*
317 * Allow overriding default TFTP block size by setting
318 * a tftp.blksize environment variable.
319 */
320 if ((tftp_blksize = getenv("tftp.blksize")) != NULL) {
321 tftp_set_blksize(h, tftp_blksize);
322 }
323
324 wbuf.t.th_opcode = htons((u_short)RRQ);
325 wtail = wbuf.t.th_stuff;
326 l = strlen(h->path);
327 #ifdef TFTP_PREPEND_PATH
328 if (l > FNAME_SIZE - (sizeof(TFTP_PREPEND_PATH) - 1))
329 return (ENAMETOOLONG);
330 bcopy(TFTP_PREPEND_PATH, wtail, sizeof(TFTP_PREPEND_PATH) - 1);
331 wtail += sizeof(TFTP_PREPEND_PATH) - 1;
332 #else
333 if (l > FNAME_SIZE)
334 return (ENAMETOOLONG);
335 #endif
336 bcopy(h->path, wtail, l + 1);
337 wtail += l + 1;
338 bcopy("octet", wtail, 6);
339 wtail += 6;
340 bcopy("blksize", wtail, 8);
341 wtail += 8;
342 blksize_l = sprintf(wtail, "%d", h->tftp_blksize);
343 wtail += blksize_l + 1;
344 bcopy("tsize", wtail, 6);
345 wtail += 6;
346 bcopy("0", wtail, 2);
347 wtail += 2;
348
349 h->iodesc->myport = htons(tftpport + (getsecs() & 0x3ff));
350 h->iodesc->destport = htons(IPPORT_TFTP);
351 h->iodesc->xid = 1; /* expected block */
352
353 h->currblock = 0;
354 h->islastblock = 0;
355 h->validsize = 0;
356
357 pkt = NULL;
358 recv_extra.tftp_handle = h;
359 res = sendrecv(h->iodesc, &sendudp, &wbuf.t, wtail - (char *)&wbuf.t,
360 &recvtftp, &pkt, (void **)&t, &recv_extra);
361 if (res == -1) {
362 free(pkt);
363 return (errno);
364 }
365
366 free(h->pkt);
367 h->pkt = pkt;
368 h->tftp_hdr = t;
369
370 if (recv_extra.rtype == OACK)
371 return (tftp_getnextblock(h));
372
373 /* Server ignored our blksize request, revert to TFTP default. */
374 h->tftp_blksize = SEGSIZE;
375
376 switch (recv_extra.rtype) {
377 case DATA: {
378 h->currblock = 1;
379 h->validsize = res;
380 h->islastblock = 0;
381 if (res < h->tftp_blksize) {
382 h->islastblock = 1; /* very short file */
383 tftp_sendack(h, h->currblock);
384 h->lastacksent = true;
385 }
386 return (0);
387 }
388 case ERROR:
389 default:
390 return (errno);
391 }
392
393 }
394
395 /* ack block, expect next */
396 static int
tftp_getnextblock(struct tftp_handle * h)397 tftp_getnextblock(struct tftp_handle *h)
398 {
399 struct {
400 u_char header[HEADER_SIZE];
401 struct tftphdr t;
402 } __packed __aligned(4) wbuf;
403 struct tftprecv_extra recv_extra;
404 char *wtail;
405 int res;
406 void *pkt;
407 struct tftphdr *t;
408
409 wbuf.t.th_opcode = htons((u_short)ACK);
410 wtail = (char *)&wbuf.t.th_block;
411 wbuf.t.th_block = htons((u_short)h->currblock);
412 wtail += 2;
413
414 h->iodesc->xid = h->currblock + 1; /* expected block */
415
416 pkt = NULL;
417 recv_extra.tftp_handle = h;
418 res = sendrecv(h->iodesc, &sendudp, &wbuf.t, wtail - (char *)&wbuf.t,
419 &recvtftp, &pkt, (void **)&t, &recv_extra);
420
421 if (res == -1) { /* 0 is OK! */
422 free(pkt);
423 return (errno);
424 }
425
426 free(h->pkt);
427 h->pkt = pkt;
428 h->tftp_hdr = t;
429 h->currblock++;
430 h->validsize = res;
431 if (res < h->tftp_blksize)
432 h->islastblock = 1; /* EOF */
433
434 if (h->islastblock == 1) {
435 /* Send an ACK for the last block */
436 wbuf.t.th_block = htons((u_short)h->currblock);
437 sendudp(h->iodesc, &wbuf.t, wtail - (char *)&wbuf.t);
438 }
439
440 return (0);
441 }
442
443 static int
tftp_open(const char * path,struct open_file * f)444 tftp_open(const char *path, struct open_file *f)
445 {
446 struct tftp_handle *tftpfile;
447 struct iodesc *io;
448 int res;
449 size_t pathsize;
450 const char *extraslash;
451
452 if (netproto != NET_TFTP)
453 return (EINVAL);
454
455 if (f->f_dev->dv_type != DEVT_NET)
456 return (EINVAL);
457
458 if (is_open)
459 return (EBUSY);
460
461 tftpfile = calloc(1, sizeof(*tftpfile));
462 if (!tftpfile)
463 return (ENOMEM);
464
465 tftpfile->tftp_blksize = TFTP_REQUESTED_BLKSIZE;
466 tftpfile->iodesc = io = socktodesc(*(int *)(f->f_devdata));
467 if (io == NULL) {
468 free(tftpfile);
469 return (EINVAL);
470 }
471
472 io->destip = rootip;
473 tftpfile->off = 0;
474 pathsize = (strlen(rootpath) + 1 + strlen(path) + 1) * sizeof(char);
475 tftpfile->path = malloc(pathsize);
476 if (tftpfile->path == NULL) {
477 free(tftpfile);
478 return (ENOMEM);
479 }
480 if (rootpath[strlen(rootpath) - 1] == '/' || path[0] == '/')
481 extraslash = "";
482 else
483 extraslash = "/";
484 res = snprintf(tftpfile->path, pathsize, "%s%s%s",
485 rootpath, extraslash, path);
486 if (res < 0 || res > pathsize) {
487 free(tftpfile->path);
488 free(tftpfile);
489 return (ENOMEM);
490 }
491
492 res = tftp_makereq(tftpfile);
493
494 if (res) {
495 free(tftpfile->path);
496 free(tftpfile->pkt);
497 free(tftpfile);
498 return (res);
499 }
500 f->f_fsdata = tftpfile;
501 is_open = 1;
502 return (0);
503 }
504
505 static int
tftp_read(struct open_file * f,void * addr,size_t size,size_t * resid)506 tftp_read(struct open_file *f, void *addr, size_t size,
507 size_t *resid /* out */)
508 {
509 struct tftp_handle *tftpfile;
510 size_t res;
511 int rc;
512
513 rc = 0;
514 res = size;
515 tftpfile = f->f_fsdata;
516
517 /* Make sure we will not read past file end */
518 if (tftpfile->tftp_tsize > 0 &&
519 tftpfile->off + size > tftpfile->tftp_tsize) {
520 size = tftpfile->tftp_tsize - tftpfile->off;
521 }
522
523 if (tftpfile->tftp_cache != NULL) {
524 bcopy(tftpfile->tftp_cache + tftpfile->off,
525 addr, size);
526
527 addr = (char *)addr + size;
528 tftpfile->off += size;
529 res -= size;
530 goto out;
531 }
532
533 while (size > 0) {
534 int needblock, count;
535
536 twiddle(32);
537
538 needblock = tftpfile->off / tftpfile->tftp_blksize + 1;
539
540 if (tftpfile->currblock > needblock) { /* seek backwards */
541 tftp_senderr(tftpfile, 0, "No error: read aborted");
542 rc = tftp_makereq(tftpfile);
543 if (rc != 0)
544 break;
545 }
546
547 while (tftpfile->currblock < needblock) {
548
549 rc = tftp_getnextblock(tftpfile);
550 if (rc) { /* no answer */
551 #ifdef TFTP_DEBUG
552 printf("tftp: read error\n");
553 #endif
554 if (tftpfile->tries > TFTP_TRIES) {
555 return (rc);
556 } else {
557 tftpfile->tries++;
558 tftp_makereq(tftpfile);
559 }
560 }
561 if (tftpfile->islastblock)
562 break;
563 }
564
565 if (tftpfile->currblock == needblock) {
566 int offinblock, inbuffer;
567
568 offinblock = tftpfile->off % tftpfile->tftp_blksize;
569
570 inbuffer = tftpfile->validsize - offinblock;
571 if (inbuffer < 0) {
572 #ifdef TFTP_DEBUG
573 printf("tftp: invalid offset %d\n",
574 tftpfile->off);
575 #endif
576 return (EINVAL);
577 }
578 count = (size < inbuffer ? size : inbuffer);
579 bcopy(tftpfile->tftp_hdr->th_data + offinblock,
580 addr, count);
581
582 addr = (char *)addr + count;
583 tftpfile->off += count;
584 size -= count;
585 res -= count;
586
587 if ((tftpfile->islastblock) && (count == inbuffer))
588 break; /* EOF */
589 } else {
590 #ifdef TFTP_DEBUG
591 printf("tftp: block %d not found\n", needblock);
592 #endif
593 return (EINVAL);
594 }
595
596 }
597
598 out:
599 if (resid != NULL)
600 *resid = res;
601 return (rc);
602 }
603
604 static int
tftp_close(struct open_file * f)605 tftp_close(struct open_file *f)
606 {
607 struct tftp_handle *tftpfile;
608 tftpfile = f->f_fsdata;
609
610 if (tftpfile->lastacksent == false)
611 tftp_senderr(tftpfile, 0, "No error: file closed");
612
613 if (tftpfile) {
614 free(tftpfile->path);
615 free(tftpfile->pkt);
616 free(tftpfile->tftp_cache);
617 free(tftpfile);
618 }
619 is_open = 0;
620 return (0);
621 }
622
623 static int
tftp_stat(struct open_file * f,struct stat * sb)624 tftp_stat(struct open_file *f, struct stat *sb)
625 {
626 struct tftp_handle *tftpfile;
627 tftpfile = f->f_fsdata;
628
629 sb->st_mode = 0444 | S_IFREG;
630 sb->st_nlink = 1;
631 sb->st_uid = 0;
632 sb->st_gid = 0;
633 sb->st_size = tftpfile->tftp_tsize;
634 return (0);
635 }
636
637 static off_t
tftp_seek(struct open_file * f,off_t offset,int where)638 tftp_seek(struct open_file *f, off_t offset, int where)
639 {
640 struct tftp_handle *tftpfile;
641 tftpfile = f->f_fsdata;
642
643 switch (where) {
644 case SEEK_SET:
645 tftpfile->off = offset;
646 break;
647 case SEEK_CUR:
648 tftpfile->off += offset;
649 break;
650 default:
651 errno = EOFFSET;
652 return (-1);
653 }
654 return (tftpfile->off);
655 }
656
657 static int
tftp_preload(struct open_file * f)658 tftp_preload(struct open_file *f)
659 {
660 struct tftp_handle *tftpfile;
661 char *cache;
662 int rc;
663 #ifdef TFTP_DEBUG
664 time_t start, end;
665 #endif
666
667 tftpfile = f->f_fsdata;
668 cache = malloc(sizeof(char) * tftpfile->tftp_tsize);
669 if (cache == NULL) {
670 printf("Couldn't allocate %ju bytes for preload caching"
671 ", disabling caching\n",
672 (uintmax_t)sizeof(char) * tftpfile->tftp_tsize);
673 return (-1);
674 }
675
676 #ifdef TFTP_DEBUG
677 start = getsecs();
678 printf("Preloading %s ", tftpfile->path);
679 #endif
680 if (tftpfile->currblock == 1)
681 bcopy(tftpfile->tftp_hdr->th_data,
682 cache,
683 tftpfile->validsize);
684 else
685 tftpfile->currblock = 0;
686
687 while (tftpfile->islastblock == 0) {
688 twiddle(32);
689 rc = tftp_getnextblock(tftpfile);
690 if (rc) {
691 free(cache);
692 printf("Got TFTP error %d, disabling caching\n", rc);
693 return (rc);
694 }
695 bcopy(tftpfile->tftp_hdr->th_data,
696 cache + (tftpfile->tftp_blksize * (tftpfile->currblock - 1)),
697 tftpfile->validsize);
698 }
699 #ifdef TFTP_DEBUG
700 end = getsecs();
701 printf("\nPreloaded %s (%ju bytes) during %jd seconds\n",
702 tftpfile->path, (intmax_t)tftpfile->tftp_tsize,
703 (intmax_t)end - start);
704 #endif
705
706 tftpfile->tftp_cache = cache;
707 return (0);
708 }
709
710 static int
tftp_set_blksize(struct tftp_handle * h,const char * str)711 tftp_set_blksize(struct tftp_handle *h, const char *str)
712 {
713 char *endptr;
714 int new_blksize;
715 int ret = 0;
716
717 if (h == NULL || str == NULL)
718 return (ret);
719
720 new_blksize =
721 (unsigned int)strtol(str, &endptr, 0);
722
723 /*
724 * Only accept blksize value if it is numeric.
725 * RFC2348 specifies that acceptable values are 8-65464.
726 * Let's choose a limit less than MAXRSPACE.
727 */
728 if (*endptr == '\0' && new_blksize >= 8 &&
729 new_blksize <= TFTP_MAX_BLKSIZE) {
730 h->tftp_blksize = new_blksize;
731 ret = 1;
732 }
733
734 return (ret);
735 }
736
737 /*
738 * In RFC2347, the TFTP Option Acknowledgement package (OACK)
739 * is used to acknowledge a client's option negotiation request.
740 * The format of an OACK packet is:
741 * +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
742 * | opc | opt1 | 0 | value1 | 0 | optN | 0 | valueN | 0 |
743 * +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
744 *
745 * opc
746 * The opcode field contains a 6, for Option Acknowledgment.
747 *
748 * opt1
749 * The first option acknowledgment, copied from the original
750 * request.
751 *
752 * value1
753 * The acknowledged value associated with the first option. If
754 * and how this value may differ from the original request is
755 * detailed in the specification for the option.
756 *
757 * optN, valueN
758 * The final option/value acknowledgment pair.
759 */
760 static int
tftp_parse_oack(struct tftp_handle * h,char * buf,size_t len)761 tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len)
762 {
763 /*
764 * We parse the OACK strings into an array
765 * of name-value pairs.
766 */
767 char *tftp_options[128] = { 0 };
768 char *val = buf;
769 int i = 0;
770 int option_idx = 0;
771 int blksize_is_set = 0;
772 int tsize = 0;
773
774 unsigned int orig_blksize;
775
776 while (option_idx < 128 && i < len) {
777 if (buf[i] == '\0') {
778 if (&buf[i] > val) {
779 tftp_options[option_idx] = val;
780 val = &buf[i] + 1;
781 ++option_idx;
782 }
783 }
784 ++i;
785 }
786
787 /* Save the block size we requested for sanity check later. */
788 orig_blksize = h->tftp_blksize;
789
790 /*
791 * Parse individual TFTP options.
792 * * "blksize" is specified in RFC2348.
793 * * "tsize" is specified in RFC2349.
794 */
795 for (i = 0; i < option_idx; i += 2) {
796 if (strcasecmp(tftp_options[i], "blksize") == 0) {
797 if (i + 1 < option_idx)
798 blksize_is_set =
799 tftp_set_blksize(h, tftp_options[i + 1]);
800 } else if (strcasecmp(tftp_options[i], "tsize") == 0) {
801 if (i + 1 < option_idx)
802 tsize = strtol(tftp_options[i + 1], NULL, 10);
803 if (tsize != 0)
804 h->tftp_tsize = tsize;
805 } else {
806 /*
807 * Do not allow any options we did not expect to be
808 * ACKed.
809 */
810 printf("unexpected tftp option '%s'\n",
811 tftp_options[i]);
812 return (-1);
813 }
814 }
815
816 if (!blksize_is_set) {
817 /*
818 * If TFTP blksize was not set, try defaulting
819 * to the legacy TFTP blksize of SEGSIZE(512)
820 */
821 h->tftp_blksize = SEGSIZE;
822 } else if (h->tftp_blksize > orig_blksize) {
823 /*
824 * Server should not be proposing block sizes that
825 * exceed what we said we can handle.
826 */
827 printf("unexpected blksize %u\n", h->tftp_blksize);
828 return (-1);
829 }
830
831 #ifdef TFTP_DEBUG
832 printf("tftp_blksize: %u\n", h->tftp_blksize);
833 printf("tftp_tsize: %lu\n", h->tftp_tsize);
834 #endif
835 return (0);
836 }
837