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 servip
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
63struct tftp_handle;
64
65static int	tftp_open(const char *path, struct open_file *f);
66static int	tftp_close(struct open_file *f);
67static int	tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len);
68static int	tftp_read(struct open_file *f, void *buf, size_t size, size_t *resid);
69static int	tftp_write(struct open_file *f, void *buf, size_t size, size_t *resid);
70static off_t	tftp_seek(struct open_file *f, off_t offset, int where);
71static int	tftp_set_blksize(struct tftp_handle *h, const char *str);
72static int	tftp_stat(struct open_file *f, struct stat *sb);
73static ssize_t sendrecv_tftp(struct tftp_handle *h,
74    ssize_t (*sproc)(struct iodesc *, void *, size_t),
75    void *sbuf, size_t ssize,
76    ssize_t (*rproc)(struct tftp_handle *h, void *, ssize_t, time_t, unsigned short *),
77    void *rbuf, size_t rsize, unsigned short *rtype);
78
79struct fs_ops tftp_fsops = {
80	"tftp",
81	tftp_open,
82	tftp_close,
83	tftp_read,
84	tftp_write,
85	tftp_seek,
86	tftp_stat,
87	null_readdir
88};
89
90extern struct in_addr servip;
91
92static int      tftpport = 2000;
93static int	is_open = 0;
94
95/*
96 * The legacy TFTP_BLKSIZE value was SEGSIZE(512).
97 * TFTP_REQUESTED_BLKSIZE of 1428 is (Ethernet MTU, less the TFTP, UDP and
98 * IP header lengths).
99 */
100#define TFTP_REQUESTED_BLKSIZE 1428
101
102/*
103 * Choose a blksize big enough so we can test with Ethernet
104 * Jumbo frames in the future.
105 */
106#define TFTP_MAX_BLKSIZE 9008
107
108struct tftp_handle {
109	struct iodesc  *iodesc;
110	int             currblock;	/* contents of lastdata */
111	int             islastblock;	/* flag */
112	int             validsize;
113	int             off;
114	char           *path;	/* saved for re-requests */
115	unsigned int	tftp_blksize;
116	unsigned long	tftp_tsize;
117	struct {
118		u_char header[HEADER_SIZE];
119		struct tftphdr t;
120		u_char space[TFTP_MAX_BLKSIZE];
121	} __packed __aligned(4) lastdata;
122};
123
124#define	TFTP_MAX_ERRCODE EOPTNEG
125static const int tftperrors[TFTP_MAX_ERRCODE + 1] = {
126	0,			/* ??? */
127	ENOENT,
128	EPERM,
129	ENOSPC,
130	EINVAL,			/* ??? */
131	EINVAL,			/* ??? */
132	EEXIST,
133	EINVAL,			/* ??? */
134	EINVAL,			/* Option negotiation failed. */
135};
136
137static int  tftp_getnextblock(struct tftp_handle *h);
138
139/* send error message back. */
140static void
141tftp_senderr(struct tftp_handle *h, u_short errcode, const char *msg)
142{
143	struct {
144		u_char header[HEADER_SIZE];
145		struct tftphdr  t;
146		u_char space[63]; /* +1 from t */
147	} __packed __aligned(4) wbuf;
148	char           *wtail;
149	int             len;
150
151	len = strlen(msg);
152	if (len > sizeof(wbuf.space))
153		len = sizeof(wbuf.space);
154
155	wbuf.t.th_opcode = htons((u_short) ERROR);
156	wbuf.t.th_code   = htons(errcode);
157
158	wtail = wbuf.t.th_msg;
159	bcopy(msg, wtail, len);
160	wtail[len] = '\0';
161	wtail += len + 1;
162
163	sendudp(h->iodesc, &wbuf.t, wtail - (char *) &wbuf.t);
164}
165
166static void
167tftp_sendack(struct tftp_handle *h)
168{
169	struct {
170		u_char header[HEADER_SIZE];
171		struct tftphdr  t;
172	} __packed __aligned(4) wbuf;
173	char           *wtail;
174
175	wbuf.t.th_opcode = htons((u_short) ACK);
176	wtail = (char *) &wbuf.t.th_block;
177	wbuf.t.th_block = htons((u_short) h->currblock);
178	wtail += 2;
179
180	sendudp(h->iodesc, &wbuf.t, wtail - (char *) &wbuf.t);
181}
182
183static ssize_t
184recvtftp(struct tftp_handle *h, void *pkt, ssize_t len, time_t tleft,
185    unsigned short *rtype)
186{
187	struct iodesc *d = h->iodesc;
188	struct tftphdr *t;
189
190	errno = 0;
191
192	len = readudp(d, pkt, len, tleft);
193
194	if (len < 4)
195		return (-1);
196
197	t = (struct tftphdr *) pkt;
198	*rtype = ntohs(t->th_opcode);
199	switch (ntohs(t->th_opcode)) {
200	case DATA: {
201		int got;
202
203		if (htons(t->th_block) != d->xid) {
204			/*
205			 * Expected block?
206			 */
207			return (-1);
208		}
209		if (d->xid == 1) {
210			/*
211			 * First data packet from new port.
212			 */
213			struct udphdr *uh;
214			uh = (struct udphdr *) pkt - 1;
215			d->destport = uh->uh_sport;
216		} /* else check uh_sport has not changed??? */
217		got = len - (t->th_data - (char *) t);
218		return got;
219	}
220	case ERROR:
221		if ((unsigned) ntohs(t->th_code) > TFTP_MAX_ERRCODE) {
222			printf("illegal tftp error %d\n", ntohs(t->th_code));
223			errno = EIO;
224		} else {
225#ifdef TFTP_DEBUG
226			printf("tftp-error %d\n", ntohs(t->th_code));
227#endif
228			errno = tftperrors[ntohs(t->th_code)];
229		}
230		return (-1);
231	case OACK: {
232		struct udphdr *uh;
233		int tftp_oack_len;
234
235		/*
236		 * Unexpected OACK. TFTP transfer already in progress.
237		 * Drop the pkt.
238		 */
239		if (d->xid != 1) {
240			return (-1);
241		}
242
243		/*
244		 * Remember which port this OACK came from, because we need
245		 * to send the ACK or errors back to it.
246		 */
247		uh = (struct udphdr *) pkt - 1;
248		d->destport = uh->uh_sport;
249
250		/* Parse options ACK-ed by the server. */
251		tftp_oack_len = len - sizeof(t->th_opcode);
252		if (tftp_parse_oack(h, t->th_u.tu_stuff, tftp_oack_len) != 0) {
253			tftp_senderr(h, EOPTNEG, "Malformed OACK");
254			errno = EIO;
255			return (-1);
256		}
257		return (0);
258	}
259	default:
260#ifdef TFTP_DEBUG
261		printf("tftp type %d not handled\n", ntohs(t->th_opcode));
262#endif
263		return (-1);
264	}
265}
266
267/* send request, expect first block (or error) */
268static int
269tftp_makereq(struct tftp_handle *h)
270{
271	struct {
272		u_char header[HEADER_SIZE];
273		struct tftphdr  t;
274		u_char space[FNAME_SIZE + 6];
275	} __packed __aligned(4) wbuf;
276	char           *wtail;
277	int             l;
278	ssize_t         res;
279	struct tftphdr *t;
280	char *tftp_blksize = NULL;
281	int blksize_l;
282	unsigned short rtype = 0;
283
284	/*
285	 * Allow overriding default TFTP block size by setting
286	 * a tftp.blksize environment variable.
287	 */
288	if ((tftp_blksize = getenv("tftp.blksize")) != NULL) {
289		tftp_set_blksize(h, tftp_blksize);
290	}
291
292	wbuf.t.th_opcode = htons((u_short) RRQ);
293	wtail = wbuf.t.th_stuff;
294	l = strlen(h->path);
295	if (l > FNAME_SIZE)
296		return (ENAMETOOLONG);
297	bcopy(h->path, wtail, l + 1);
298	wtail += l + 1;
299	bcopy("octet", wtail, 6);
300	wtail += 6;
301	bcopy("blksize", wtail, 8);
302	wtail += 8;
303	blksize_l = sprintf(wtail, "%d", h->tftp_blksize);
304	wtail += blksize_l + 1;
305	bcopy("tsize", wtail, 6);
306	wtail += 6;
307	bcopy("0", wtail, 2);
308	wtail += 2;
309
310	t = &h->lastdata.t;
311
312	/* h->iodesc->myport = htons(--tftpport); */
313	h->iodesc->myport = htons(tftpport + (getsecs() & 0x3ff));
314	h->iodesc->destport = htons(IPPORT_TFTP);
315	h->iodesc->xid = 1;	/* expected block */
316
317	h->currblock = 0;
318	h->islastblock = 0;
319	h->validsize = 0;
320
321	res = sendrecv_tftp(h, &sendudp, &wbuf.t, wtail - (char *) &wbuf.t,
322		       &recvtftp, t, sizeof(*t) + h->tftp_blksize, &rtype);
323
324	if (rtype == OACK)
325		return (tftp_getnextblock(h));
326
327	/* Server ignored our blksize request, revert to TFTP default. */
328	h->tftp_blksize = SEGSIZE;
329
330	switch (rtype) {
331		case DATA: {
332			h->currblock = 1;
333			h->validsize = res;
334			h->islastblock = 0;
335			if (res < h->tftp_blksize) {
336				h->islastblock = 1;	/* very short file */
337				tftp_sendack(h);
338			}
339			return (0);
340		}
341		case ERROR:
342		default:
343			return (errno);
344	}
345
346}
347
348/* ack block, expect next */
349static int
350tftp_getnextblock(struct tftp_handle *h)
351{
352	struct {
353		u_char header[HEADER_SIZE];
354		struct tftphdr t;
355	} __packed __aligned(4) wbuf;
356	char           *wtail;
357	int             res;
358	struct tftphdr *t;
359	unsigned short rtype = 0;
360	wbuf.t.th_opcode = htons((u_short) ACK);
361	wtail = (char *) &wbuf.t.th_block;
362	wbuf.t.th_block = htons((u_short) h->currblock);
363	wtail += 2;
364
365	t = &h->lastdata.t;
366
367	h->iodesc->xid = h->currblock + 1;	/* expected block */
368
369	res = sendrecv_tftp(h, &sendudp, &wbuf.t, wtail - (char *) &wbuf.t,
370		       &recvtftp, t, sizeof(*t) + h->tftp_blksize, &rtype);
371
372	if (res == -1)		/* 0 is OK! */
373		return (errno);
374
375	h->currblock++;
376	h->validsize = res;
377	if (res < h->tftp_blksize)
378		h->islastblock = 1;	/* EOF */
379
380	if (h->islastblock == 1) {
381		/* Send an ACK for the last block */
382		wbuf.t.th_block = htons((u_short) h->currblock);
383		sendudp(h->iodesc, &wbuf.t, wtail - (char *)&wbuf.t);
384	}
385
386	return (0);
387}
388
389static int
390tftp_open(const char *path, struct open_file *f)
391{
392	struct tftp_handle *tftpfile;
393	struct iodesc  *io;
394	int             res;
395
396#ifndef __i386__
397	if (strcmp(f->f_dev->dv_name, "net") != 0)
398		return (EINVAL);
399#endif
400
401	if (is_open)
402		return (EBUSY);
403
404	tftpfile = (struct tftp_handle *) malloc(sizeof(*tftpfile));
405	if (!tftpfile)
406		return (ENOMEM);
407
408	memset(tftpfile, 0, sizeof(*tftpfile));
409	tftpfile->tftp_blksize = TFTP_REQUESTED_BLKSIZE;
410	tftpfile->iodesc = io = socktodesc(*(int *) (f->f_devdata));
411	if (io == NULL)
412		return (EINVAL);
413
414	io->destip = servip;
415	tftpfile->off = 0;
416	tftpfile->path = strdup(path);
417	if (tftpfile->path == NULL) {
418	    free(tftpfile);
419	    return(ENOMEM);
420	}
421
422	res = tftp_makereq(tftpfile);
423
424	if (res) {
425		free(tftpfile->path);
426		free(tftpfile);
427		return (res);
428	}
429	f->f_fsdata = (void *) tftpfile;
430	is_open = 1;
431	return (0);
432}
433
434static int
435tftp_read(struct open_file *f, void *addr, size_t size,
436    size_t *resid /* out */)
437{
438	struct tftp_handle *tftpfile;
439	static int      tc = 0;
440	tftpfile = (struct tftp_handle *) f->f_fsdata;
441
442	while (size > 0) {
443		int needblock, count;
444
445		if (!(tc++ % 16))
446			twiddle();
447
448		needblock = tftpfile->off / tftpfile->tftp_blksize + 1;
449
450		if (tftpfile->currblock > needblock) {	/* seek backwards */
451			tftp_senderr(tftpfile, 0, "No error: read aborted");
452			tftp_makereq(tftpfile);	/* no error check, it worked
453						 * for open */
454		}
455
456		while (tftpfile->currblock < needblock) {
457			int res;
458
459			res = tftp_getnextblock(tftpfile);
460			if (res) {	/* no answer */
461#ifdef TFTP_DEBUG
462				printf("tftp: read error\n");
463#endif
464				return (res);
465			}
466			if (tftpfile->islastblock)
467				break;
468		}
469
470		if (tftpfile->currblock == needblock) {
471			int offinblock, inbuffer;
472
473			offinblock = tftpfile->off % tftpfile->tftp_blksize;
474
475			inbuffer = tftpfile->validsize - offinblock;
476			if (inbuffer < 0) {
477#ifdef TFTP_DEBUG
478				printf("tftp: invalid offset %d\n",
479				    tftpfile->off);
480#endif
481				return (EINVAL);
482			}
483			count = (size < inbuffer ? size : inbuffer);
484			bcopy(tftpfile->lastdata.t.th_data + offinblock,
485			    addr, count);
486
487			addr = (char *)addr + count;
488			tftpfile->off += count;
489			size -= count;
490
491			if ((tftpfile->islastblock) && (count == inbuffer))
492				break;	/* EOF */
493		} else {
494#ifdef TFTP_DEBUG
495			printf("tftp: block %d not found\n", needblock);
496#endif
497			return (EINVAL);
498		}
499
500	}
501
502	if (resid)
503		*resid = size;
504	return (0);
505}
506
507static int
508tftp_close(struct open_file *f)
509{
510	struct tftp_handle *tftpfile;
511	tftpfile = (struct tftp_handle *) f->f_fsdata;
512
513	/* let it time out ... */
514
515	if (tftpfile) {
516		free(tftpfile->path);
517		free(tftpfile);
518	}
519	is_open = 0;
520	return (0);
521}
522
523static int
524tftp_write(struct open_file *f __unused, void *start __unused, size_t size __unused,
525    size_t *resid __unused /* out */)
526{
527	return (EROFS);
528}
529
530static int
531tftp_stat(struct open_file *f, struct stat *sb)
532{
533	struct tftp_handle *tftpfile;
534	tftpfile = (struct tftp_handle *) f->f_fsdata;
535
536	sb->st_mode = 0444 | S_IFREG;
537	sb->st_nlink = 1;
538	sb->st_uid = 0;
539	sb->st_gid = 0;
540	sb->st_size = -1;
541	return (0);
542}
543
544static off_t
545tftp_seek(struct open_file *f, off_t offset, int where)
546{
547	struct tftp_handle *tftpfile;
548	tftpfile = (struct tftp_handle *) f->f_fsdata;
549
550	switch (where) {
551	case SEEK_SET:
552		tftpfile->off = offset;
553		break;
554	case SEEK_CUR:
555		tftpfile->off += offset;
556		break;
557	default:
558		errno = EOFFSET;
559		return (-1);
560	}
561	return (tftpfile->off);
562}
563
564static ssize_t
565sendrecv_tftp(struct tftp_handle *h,
566    ssize_t (*sproc)(struct iodesc *, void *, size_t),
567    void *sbuf, size_t ssize,
568    ssize_t (*rproc)(struct tftp_handle *, void *, ssize_t, time_t, unsigned short *),
569    void *rbuf, size_t rsize, unsigned short *rtype)
570{
571	struct iodesc *d = h->iodesc;
572	ssize_t cc;
573	time_t t, t1, tleft;
574
575#ifdef TFTP_DEBUG
576	if (debug)
577		printf("sendrecv: called\n");
578#endif
579
580	tleft = MINTMO;
581	t = t1 = getsecs();
582	for (;;) {
583		if ((getsecs() - t) > MAXTMO) {
584			errno = ETIMEDOUT;
585			return -1;
586		}
587
588		cc = (*sproc)(d, sbuf, ssize);
589		if (cc != -1 && cc < ssize)
590			panic("sendrecv: short write! (%zd < %zu)",
591			    cc, ssize);
592
593		if (cc == -1) {
594			/* Error on transmit; wait before retrying */
595			while ((getsecs() - t1) < tleft);
596			continue;
597		}
598
599recvnext:
600		/* Try to get a packet and process it. */
601		cc = (*rproc)(h, rbuf, rsize, tleft, rtype);
602		/* Return on data, EOF or real error. */
603		if (cc != -1 || errno != 0)
604			return (cc);
605		if ((getsecs() - t1) < tleft) {
606		    goto recvnext;
607		}
608
609		/* Timed out or didn't get the packet we're waiting for */
610		tleft += MINTMO;
611		if (tleft > (2 * MINTMO)) {
612			tleft = (2 * MINTMO);
613		}
614		t1 = getsecs();
615	}
616}
617
618static int
619tftp_set_blksize(struct tftp_handle *h, const char *str)
620{
621        char *endptr;
622	int new_blksize;
623	int ret = 0;
624
625	if (h == NULL || str == NULL)
626		return (ret);
627
628	new_blksize =
629	    (unsigned int)strtol(str, &endptr, 0);
630
631	/*
632	 * Only accept blksize value if it is numeric.
633	 * RFC2348 specifies that acceptable values are 8-65464.
634	 * Let's choose a limit less than MAXRSPACE.
635	 */
636	if (*endptr == '\0' && new_blksize >= 8
637	    && new_blksize <= TFTP_MAX_BLKSIZE) {
638		h->tftp_blksize = new_blksize;
639		ret = 1;
640	}
641
642	return (ret);
643}
644
645/*
646 * In RFC2347, the TFTP Option Acknowledgement package (OACK)
647 * is used to acknowledge a client's option negotiation request.
648 * The format of an OACK packet is:
649 *    +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
650 *    |  opc  |  opt1  | 0 | value1 | 0 |  optN  | 0 | valueN | 0 |
651 *    +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
652 *
653 *    opc
654 *       The opcode field contains a 6, for Option Acknowledgment.
655 *
656 *    opt1
657 *       The first option acknowledgment, copied from the original
658 *       request.
659 *
660 *    value1
661 *       The acknowledged value associated with the first option.  If
662 *       and how this value may differ from the original request is
663 *       detailed in the specification for the option.
664 *
665 *    optN, valueN
666 *       The final option/value acknowledgment pair.
667 */
668static int
669tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len)
670{
671	/*
672	 *  We parse the OACK strings into an array
673	 *  of name-value pairs.
674	 */
675	char *tftp_options[128] = { 0 };
676	char *val = buf;
677	int i = 0;
678	int option_idx = 0;
679	int blksize_is_set = 0;
680	int tsize = 0;
681
682	unsigned int orig_blksize;
683
684	while (option_idx < 128 && i < len) {
685		if (buf[i] == '\0') {
686			if (&buf[i] > val) {
687				tftp_options[option_idx] = val;
688				val = &buf[i] + 1;
689				++option_idx;
690			}
691		}
692		++i;
693	}
694
695	/* Save the block size we requested for sanity check later. */
696	orig_blksize = h->tftp_blksize;
697
698	/*
699	 * Parse individual TFTP options.
700	 *    * "blksize" is specified in RFC2348.
701	 *    * "tsize" is specified in RFC2349.
702	 */
703	for (i = 0; i < option_idx; i += 2) {
704	    if (strcasecmp(tftp_options[i], "blksize") == 0) {
705		if (i + 1 < option_idx)
706			blksize_is_set =
707			    tftp_set_blksize(h, tftp_options[i + 1]);
708	    } else if (strcasecmp(tftp_options[i], "tsize") == 0) {
709		if (i + 1 < option_idx)
710			tsize = strtol(tftp_options[i + 1], (char **)NULL, 10);
711	    } else {
712		/* Do not allow any options we did not expect to be ACKed. */
713		printf("unexpected tftp option '%s'\n", tftp_options[i]);
714		return (-1);
715	    }
716	}
717
718	if (!blksize_is_set) {
719		/*
720		 * If TFTP blksize was not set, try defaulting
721		 * to the legacy TFTP blksize of SEGSIZE(512)
722		 */
723		h->tftp_blksize = SEGSIZE;
724	} else if (h->tftp_blksize > orig_blksize) {
725		/*
726		 * Server should not be proposing block sizes that
727		 * exceed what we said we can handle.
728		 */
729		printf("unexpected blksize %u\n", h->tftp_blksize);
730		return (-1);
731	}
732
733#ifdef TFTP_DEBUG
734	printf("tftp_blksize: %u\n", h->tftp_blksize);
735	printf("tftp_tsize: %lu\n", h->tftp_tsize);
736#endif
737	return 0;
738}
739