summaryrefslogtreecommitdiffstats
path: root/lib/libstand/tftp.c
blob: 001cbfd6d1f01e25962066d70069903cf3985333 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
/*	$NetBSD: tftp.c,v 1.4 1997/09/17 16:57:07 drochner Exp $	 */

/*
 * Copyright (c) 1996
 *	Matthias Drochner.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed for the NetBSD Project
 *	by Matthias Drochner.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

/*
 * Simple TFTP implementation for libsa.
 * Assumes:
 *  - socket descriptor (int) at open_file->f_devdata
 *  - server host IP in global servip
 * Restrictions:
 *  - read only
 *  - lseek only with SEEK_SET or SEEK_CUR
 *  - no big time differences between transfers (<tftp timeout)
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <netinet/in.h>
#include <netinet/udp.h>
#include <netinet/in_systm.h>
#include <arpa/tftp.h>

#include <string.h>

#include "stand.h"
#include "net.h"
#include "netif.h"

#include "tftp.h"

struct tftp_handle;

static int	tftp_open(const char *path, struct open_file *f);
static int	tftp_close(struct open_file *f);
static int	tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len);
static int	tftp_read(struct open_file *f, void *buf, size_t size, size_t *resid);
static int	tftp_write(struct open_file *f, void *buf, size_t size, size_t *resid);
static off_t	tftp_seek(struct open_file *f, off_t offset, int where);
static int	tftp_set_blksize(struct tftp_handle *h, const char *str);
static int	tftp_stat(struct open_file *f, struct stat *sb);
static ssize_t sendrecv_tftp(struct tftp_handle *h,
    ssize_t (*sproc)(struct iodesc *, void *, size_t),
    void *sbuf, size_t ssize,
    ssize_t (*rproc)(struct tftp_handle *h, void *, ssize_t, time_t, unsigned short *),
    void *rbuf, size_t rsize, unsigned short *rtype);

struct fs_ops tftp_fsops = {
	"tftp",
	tftp_open,
	tftp_close,
	tftp_read,
	tftp_write,
	tftp_seek,
	tftp_stat,
	null_readdir
};

extern struct in_addr servip;

static int      tftpport = 2000;
static int	is_open = 0;

/*
 * The legacy TFTP_BLKSIZE value was SEGSIZE(512).
 * TFTP_REQUESTED_BLKSIZE of 1428 is (Ethernet MTU, less the TFTP, UDP and
 * IP header lengths).
 */
#define TFTP_REQUESTED_BLKSIZE 1428

/*
 * Choose a blksize big enough so we can test with Ethernet
 * Jumbo frames in the future.
 */
#define TFTP_MAX_BLKSIZE 9008

struct tftp_handle {
	struct iodesc  *iodesc;
	int             currblock;	/* contents of lastdata */
	int             islastblock;	/* flag */
	int             validsize;
	int             off;
	char           *path;	/* saved for re-requests */
	unsigned int	tftp_blksize;
	unsigned long	tftp_tsize;
	struct {
		u_char header[HEADER_SIZE];
		struct tftphdr t;
		u_char space[TFTP_MAX_BLKSIZE];
	} __packed __aligned(4) lastdata;
};

#define	TFTP_MAX_ERRCODE EOPTNEG
static const int tftperrors[TFTP_MAX_ERRCODE + 1] = {
	0,			/* ??? */
	ENOENT,
	EPERM,
	ENOSPC,
	EINVAL,			/* ??? */
	EINVAL,			/* ??? */
	EEXIST,
	EINVAL,			/* ??? */
	EINVAL,			/* Option negotiation failed. */
};

static int  tftp_getnextblock(struct tftp_handle *h);

/* send error message back. */
static void
tftp_senderr(struct tftp_handle *h, u_short errcode, const char *msg)
{
	struct {
		u_char header[HEADER_SIZE];
		struct tftphdr  t;
		u_char space[63]; /* +1 from t */
	} __packed __aligned(4) wbuf;
	char           *wtail;
	int             len;

	len = strlen(msg);
	if (len > sizeof(wbuf.space))
		len = sizeof(wbuf.space);

	wbuf.t.th_opcode = htons((u_short) ERROR);
	wbuf.t.th_code   = htons(errcode);

	wtail = wbuf.t.th_msg;
	bcopy(msg, wtail, len);
	wtail[len] = '\0';
	wtail += len + 1;

	sendudp(h->iodesc, &wbuf.t, wtail - (char *) &wbuf.t);
}

static void
tftp_sendack(struct tftp_handle *h)
{
	struct {
		u_char header[HEADER_SIZE];
		struct tftphdr  t;
	} __packed __aligned(4) wbuf;
	char           *wtail;

	wbuf.t.th_opcode = htons((u_short) ACK);
	wtail = (char *) &wbuf.t.th_block;
	wbuf.t.th_block = htons((u_short) h->currblock);
	wtail += 2;

	sendudp(h->iodesc, &wbuf.t, wtail - (char *) &wbuf.t);
}

static ssize_t
recvtftp(struct tftp_handle *h, void *pkt, ssize_t len, time_t tleft,
    unsigned short *rtype)
{
	struct iodesc *d = h->iodesc;
	struct tftphdr *t;

	errno = 0;

	len = readudp(d, pkt, len, tleft);

	if (len < 4)
		return (-1);

	t = (struct tftphdr *) pkt;
	*rtype = ntohs(t->th_opcode);
	switch (ntohs(t->th_opcode)) {
	case DATA: {
		int got;

		if (htons(t->th_block) != d->xid) {
			/*
			 * Expected block?
			 */
			return (-1);
		}
		if (d->xid == 1) {
			/*
			 * First data packet from new port.
			 */
			struct udphdr *uh;
			uh = (struct udphdr *) pkt - 1;
			d->destport = uh->uh_sport;
		} /* else check uh_sport has not changed??? */
		got = len - (t->th_data - (char *) t);
		return got;
	}
	case ERROR:
		if ((unsigned) ntohs(t->th_code) > TFTP_MAX_ERRCODE) {
			printf("illegal tftp error %d\n", ntohs(t->th_code));
			errno = EIO;
		} else {
#ifdef TFTP_DEBUG
			printf("tftp-error %d\n", ntohs(t->th_code));
#endif
			errno = tftperrors[ntohs(t->th_code)];
		}
		return (-1);
	case OACK: {
		struct udphdr *uh;
		int tftp_oack_len;

		/* 
		 * Unexpected OACK. TFTP transfer already in progress. 
		 * Drop the pkt.
		 */
		if (d->xid != 1) {
			return (-1);
		}

		/*
		 * Remember which port this OACK came from, because we need
		 * to send the ACK or errors back to it.
		 */
		uh = (struct udphdr *) pkt - 1;
		d->destport = uh->uh_sport;
		
		/* Parse options ACK-ed by the server. */
		tftp_oack_len = len - sizeof(t->th_opcode);
		if (tftp_parse_oack(h, t->th_u.tu_stuff, tftp_oack_len) != 0) {
			tftp_senderr(h, EOPTNEG, "Malformed OACK");
			errno = EIO;
			return (-1);
		}
		return (0);
	}
	default:
#ifdef TFTP_DEBUG
		printf("tftp type %d not handled\n", ntohs(t->th_opcode));
#endif
		return (-1);
	}
}

/* send request, expect first block (or error) */
static int
tftp_makereq(struct tftp_handle *h)
{
	struct {
		u_char header[HEADER_SIZE];
		struct tftphdr  t;
		u_char space[FNAME_SIZE + 6];
	} __packed __aligned(4) wbuf;
	char           *wtail;
	int             l;
	ssize_t         res;
	struct tftphdr *t;
	char *tftp_blksize = NULL;
	int blksize_l;
	unsigned short rtype = 0;

	/*
	 * Allow overriding default TFTP block size by setting
	 * a tftp.blksize environment variable.
	 */
	if ((tftp_blksize = getenv("tftp.blksize")) != NULL) {
		tftp_set_blksize(h, tftp_blksize);
	}

	wbuf.t.th_opcode = htons((u_short) RRQ);
	wtail = wbuf.t.th_stuff;
	l = strlen(h->path);
#ifdef TFTP_PREPEND_PATH
	if (l > FNAME_SIZE - (sizeof(TFTP_PREPEND_PATH) - 1))
		return (ENAMETOOLONG);
	bcopy(TFTP_PREPEND_PATH, wtail, sizeof(TFTP_PREPEND_PATH) - 1);
	wtail += sizeof(TFTP_PREPEND_PATH) - 1;
#else
	if (l > FNAME_SIZE)
		return (ENAMETOOLONG);
#endif
	bcopy(h->path, wtail, l + 1);
	wtail += l + 1;
	bcopy("octet", wtail, 6);
	wtail += 6;
	bcopy("blksize", wtail, 8);
	wtail += 8;
	blksize_l = sprintf(wtail, "%d", h->tftp_blksize);
	wtail += blksize_l + 1;
	bcopy("tsize", wtail, 6);
	wtail += 6;
	bcopy("0", wtail, 2);
	wtail += 2;

	t = &h->lastdata.t;

	/* h->iodesc->myport = htons(--tftpport); */
	h->iodesc->myport = htons(tftpport + (getsecs() & 0x3ff));
	h->iodesc->destport = htons(IPPORT_TFTP);
	h->iodesc->xid = 1;	/* expected block */

	h->currblock = 0;
	h->islastblock = 0;
	h->validsize = 0;

	res = sendrecv_tftp(h, &sendudp, &wbuf.t, wtail - (char *) &wbuf.t,
		       &recvtftp, t, sizeof(*t) + h->tftp_blksize, &rtype);

	if (rtype == OACK)
		return (tftp_getnextblock(h));

	/* Server ignored our blksize request, revert to TFTP default. */
	h->tftp_blksize = SEGSIZE;

	switch (rtype) {
		case DATA: {
			h->currblock = 1;
			h->validsize = res;
			h->islastblock = 0;
			if (res < h->tftp_blksize) {
				h->islastblock = 1;	/* very short file */
				tftp_sendack(h);
			}
			return (0);
		}
		case ERROR:
		default:
			return (errno);
	}

}

/* ack block, expect next */
static int 
tftp_getnextblock(struct tftp_handle *h)
{
	struct {
		u_char header[HEADER_SIZE];
		struct tftphdr t;
	} __packed __aligned(4) wbuf;
	char           *wtail;
	int             res;
	struct tftphdr *t;
	unsigned short rtype = 0;
	wbuf.t.th_opcode = htons((u_short) ACK);
	wtail = (char *) &wbuf.t.th_block;
	wbuf.t.th_block = htons((u_short) h->currblock);
	wtail += 2;

	t = &h->lastdata.t;

	h->iodesc->xid = h->currblock + 1;	/* expected block */

	res = sendrecv_tftp(h, &sendudp, &wbuf.t, wtail - (char *) &wbuf.t,
		       &recvtftp, t, sizeof(*t) + h->tftp_blksize, &rtype);

	if (res == -1)		/* 0 is OK! */
		return (errno);

	h->currblock++;
	h->validsize = res;
	if (res < h->tftp_blksize)
		h->islastblock = 1;	/* EOF */

	if (h->islastblock == 1) {
		/* Send an ACK for the last block */ 
		wbuf.t.th_block = htons((u_short) h->currblock);
		sendudp(h->iodesc, &wbuf.t, wtail - (char *)&wbuf.t);
	}

	return (0);
}

static int
tftp_open(const char *path, struct open_file *f)
{
	struct tftp_handle *tftpfile;
	struct iodesc  *io;
	int             res;
	size_t          pathsize;
	const char     *extraslash;

	if (strcmp(f->f_dev->dv_name, "net") != 0) {
#ifdef __i386__
		if (strcmp(f->f_dev->dv_name, "pxe") != 0)
			return (EINVAL);
#else
		return (EINVAL);
#endif
	}

	if (is_open)
		return (EBUSY);

	tftpfile = (struct tftp_handle *) malloc(sizeof(*tftpfile));
	if (!tftpfile)
		return (ENOMEM);

	memset(tftpfile, 0, sizeof(*tftpfile));
	tftpfile->tftp_blksize = TFTP_REQUESTED_BLKSIZE;
	tftpfile->iodesc = io = socktodesc(*(int *) (f->f_devdata));
	if (io == NULL)
		return (EINVAL);

	io->destip = servip;
	tftpfile->off = 0;
	pathsize = (strlen(rootpath) + 1 + strlen(path) + 1) * sizeof(char);
	tftpfile->path = malloc(pathsize);
	if (tftpfile->path == NULL) {
		free(tftpfile);
		return(ENOMEM);
	}
	if (rootpath[strlen(rootpath) - 1] == '/' || path[0] == '/')
		extraslash = "";
	else
		extraslash = "/";
	res = snprintf(tftpfile->path, pathsize, "%s%s%s",
	    rootpath, extraslash, path);
	if (res < 0 || res > pathsize) {
		free(tftpfile->path);
		free(tftpfile);
		return(ENOMEM);
	}

	res = tftp_makereq(tftpfile);

	if (res) {
		free(tftpfile->path);
		free(tftpfile);
		return (res);
	}
	f->f_fsdata = (void *) tftpfile;
	is_open = 1;
	return (0);
}

static int
tftp_read(struct open_file *f, void *addr, size_t size,
    size_t *resid /* out */)
{
	struct tftp_handle *tftpfile;
	tftpfile = (struct tftp_handle *) f->f_fsdata;

	while (size > 0) {
		int needblock, count;

		twiddle(32);

		needblock = tftpfile->off / tftpfile->tftp_blksize + 1;

		if (tftpfile->currblock > needblock) {	/* seek backwards */
			tftp_senderr(tftpfile, 0, "No error: read aborted");
			tftp_makereq(tftpfile);	/* no error check, it worked
						 * for open */
		}

		while (tftpfile->currblock < needblock) {
			int res;

			res = tftp_getnextblock(tftpfile);
			if (res) {	/* no answer */
#ifdef TFTP_DEBUG
				printf("tftp: read error\n");
#endif
				return (res);
			}
			if (tftpfile->islastblock)
				break;
		}

		if (tftpfile->currblock == needblock) {
			int offinblock, inbuffer;

			offinblock = tftpfile->off % tftpfile->tftp_blksize;

			inbuffer = tftpfile->validsize - offinblock;
			if (inbuffer < 0) {
#ifdef TFTP_DEBUG
				printf("tftp: invalid offset %d\n",
				    tftpfile->off);
#endif
				return (EINVAL);
			}
			count = (size < inbuffer ? size : inbuffer);
			bcopy(tftpfile->lastdata.t.th_data + offinblock,
			    addr, count);

			addr = (char *)addr + count;
			tftpfile->off += count;
			size -= count;

			if ((tftpfile->islastblock) && (count == inbuffer))
				break;	/* EOF */
		} else {
#ifdef TFTP_DEBUG
			printf("tftp: block %d not found\n", needblock);
#endif
			return (EINVAL);
		}

	}

	if (resid)
		*resid = size;
	return (0);
}

static int 
tftp_close(struct open_file *f)
{
	struct tftp_handle *tftpfile;
	tftpfile = (struct tftp_handle *) f->f_fsdata;

	/* let it time out ... */

	if (tftpfile) {
		free(tftpfile->path);
		free(tftpfile);
	}
	is_open = 0;
	return (0);
}

static int
tftp_write(struct open_file *f __unused, void *start __unused, size_t size __unused,
    size_t *resid __unused /* out */)
{
	return (EROFS);
}

static int 
tftp_stat(struct open_file *f, struct stat *sb)
{
	struct tftp_handle *tftpfile;
	tftpfile = (struct tftp_handle *) f->f_fsdata;

	sb->st_mode = 0444 | S_IFREG;
	sb->st_nlink = 1;
	sb->st_uid = 0;
	sb->st_gid = 0;
	sb->st_size = -1;
	return (0);
}

static off_t
tftp_seek(struct open_file *f, off_t offset, int where)
{
	struct tftp_handle *tftpfile;
	tftpfile = (struct tftp_handle *) f->f_fsdata;

	switch (where) {
	case SEEK_SET:
		tftpfile->off = offset;
		break;
	case SEEK_CUR:
		tftpfile->off += offset;
		break;
	default:
		errno = EOFFSET;
		return (-1);
	}
	return (tftpfile->off);
}

static ssize_t
sendrecv_tftp(struct tftp_handle *h,
    ssize_t (*sproc)(struct iodesc *, void *, size_t),
    void *sbuf, size_t ssize,
    ssize_t (*rproc)(struct tftp_handle *, void *, ssize_t, time_t, unsigned short *),
    void *rbuf, size_t rsize, unsigned short *rtype)
{
	struct iodesc *d = h->iodesc;
	ssize_t cc;
	time_t t, t1, tleft;

#ifdef TFTP_DEBUG
	if (debug)
		printf("sendrecv: called\n");
#endif

	tleft = MINTMO;
	t = t1 = getsecs();
	for (;;) {
		if ((getsecs() - t) > MAXTMO) {
			errno = ETIMEDOUT;
			return -1;
		}

		cc = (*sproc)(d, sbuf, ssize);
		if (cc != -1 && cc < ssize)
			panic("sendrecv: short write! (%zd < %zu)",
			    cc, ssize);

		if (cc == -1) {
			/* Error on transmit; wait before retrying */
			while ((getsecs() - t1) < tleft);
			continue;
		}

recvnext:
		/* Try to get a packet and process it. */
		cc = (*rproc)(h, rbuf, rsize, tleft, rtype);
		/* Return on data, EOF or real error. */
		if (cc != -1 || errno != 0)
			return (cc);
		if ((getsecs() - t1) < tleft) {
		    goto recvnext;
		}

		/* Timed out or didn't get the packet we're waiting for */
		tleft += MINTMO;
		if (tleft > (2 * MINTMO)) {
			tleft = (2 * MINTMO);
		}
		t1 = getsecs();
	}
}

static int
tftp_set_blksize(struct tftp_handle *h, const char *str)
{
        char *endptr;
	int new_blksize;
	int ret = 0;

	if (h == NULL || str == NULL)
		return (ret);

	new_blksize =
	    (unsigned int)strtol(str, &endptr, 0);

	/*
	 * Only accept blksize value if it is numeric.
	 * RFC2348 specifies that acceptable values are 8-65464.
	 * Let's choose a limit less than MAXRSPACE.
	 */
	if (*endptr == '\0' && new_blksize >= 8
	    && new_blksize <= TFTP_MAX_BLKSIZE) {
		h->tftp_blksize = new_blksize;
		ret = 1;
	}

	return (ret);
}

/*
 * In RFC2347, the TFTP Option Acknowledgement package (OACK)
 * is used to acknowledge a client's option negotiation request.
 * The format of an OACK packet is:
 *    +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
 *    |  opc  |  opt1  | 0 | value1 | 0 |  optN  | 0 | valueN | 0 |
 *    +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
 *
 *    opc
 *       The opcode field contains a 6, for Option Acknowledgment.
 *
 *    opt1
 *       The first option acknowledgment, copied from the original
 *       request.
 *
 *    value1
 *       The acknowledged value associated with the first option.  If
 *       and how this value may differ from the original request is
 *       detailed in the specification for the option.
 *
 *    optN, valueN
 *       The final option/value acknowledgment pair.
 */
static int 
tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len)
{
	/* 
	 *  We parse the OACK strings into an array
	 *  of name-value pairs.
	 */
	char *tftp_options[128] = { 0 };
	char *val = buf;
	int i = 0;
	int option_idx = 0;
	int blksize_is_set = 0;
	int tsize = 0;
	
	unsigned int orig_blksize;

	while (option_idx < 128 && i < len) {
		if (buf[i] == '\0') {
			if (&buf[i] > val) {
				tftp_options[option_idx] = val;
				val = &buf[i] + 1;
				++option_idx;
			}
		}
		++i;
	}

	/* Save the block size we requested for sanity check later. */
	orig_blksize = h->tftp_blksize;

	/* 
	 * Parse individual TFTP options.
	 *    * "blksize" is specified in RFC2348.
	 *    * "tsize" is specified in RFC2349.
	 */ 
	for (i = 0; i < option_idx; i += 2) {
	    if (strcasecmp(tftp_options[i], "blksize") == 0) {
		if (i + 1 < option_idx)
			blksize_is_set =
			    tftp_set_blksize(h, tftp_options[i + 1]);
	    } else if (strcasecmp(tftp_options[i], "tsize") == 0) {
		if (i + 1 < option_idx)
			tsize = strtol(tftp_options[i + 1], (char **)NULL, 10);
	    } else {
		/* Do not allow any options we did not expect to be ACKed. */
		printf("unexpected tftp option '%s'\n", tftp_options[i]);
		return (-1);
	    }
	}

	if (!blksize_is_set) {
		/*
		 * If TFTP blksize was not set, try defaulting
		 * to the legacy TFTP blksize of SEGSIZE(512)
		 */
		h->tftp_blksize = SEGSIZE;
	} else if (h->tftp_blksize > orig_blksize) {
		/*
		 * Server should not be proposing block sizes that
		 * exceed what we said we can handle.
		 */
		printf("unexpected blksize %u\n", h->tftp_blksize);
		return (-1);
	}

#ifdef TFTP_DEBUG
	printf("tftp_blksize: %u\n", h->tftp_blksize);
	printf("tftp_tsize: %lu\n", h->tftp_tsize);
#endif
	return 0;
}
OpenPOWER on IntegriCloud