VirtualBox

source: vbox/trunk/src/VBox/NetworkServices/NAT/proxy_tftpd.c

Last change on this file was 106061, checked in by vboxsync, 3 months ago

Copyright year updates by scm.

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1/* $Id: proxy_tftpd.c 106061 2024-09-16 14:03:52Z vboxsync $ */
2/** @file
3 * NAT Network - TFTP server.
4 */
5
6/*
7 * Copyright (C) 2013-2024 Oracle and/or its affiliates.
8 *
9 * This file is part of VirtualBox base platform packages, as
10 * available from https://www.virtualbox.org.
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation, in version 3 of the
15 * License.
16 *
17 * This program is distributed in the hope that it will be useful, but
18 * WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 * General Public License for more details.
21 *
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, see <https://www.gnu.org/licenses>.
24 *
25 * SPDX-License-Identifier: GPL-3.0-only
26 */
27
28#define LOG_GROUP LOG_GROUP_NAT_SERVICE
29
30#include "winutils.h"
31
32#include "proxy.h"
33#include "tftp.h"
34
35#ifndef RT_OS_WINDOWS
36#include <sys/types.h>
37#include <sys/stat.h>
38#include <errno.h>
39#include <fcntl.h>
40#include <stdarg.h>
41#include <stdio.h>
42#include <string.h>
43#include <unistd.h>
44#else
45#include <sys/types.h>
46#include <sys/stat.h>
47#include <errno.h>
48#include <fcntl.h>
49#include <io.h>
50#include <stdarg.h>
51#include <stdio.h>
52#include <string.h>
53
54# define O_RDONLY _O_RDONLY
55# define S_ISREG(x) ((x) & _S_IFREG)
56#endif
57
58#include "lwip/timers.h"
59#include "lwip/udp.h"
60
61#include <iprt/string.h>
62
63struct xfer {
64 struct udp_pcb *pcb;
65 int fd;
66 unsigned int ack;
67 struct pbuf *pbuf;
68
69 struct pbuf *oack;
70
71 int rexmit;
72
73 ipX_addr_t peer_ip;
74 u16_t peer_port;
75
76 char *filename;
77 int octet;
78
79 /* options */
80 unsigned int blksize;
81 int blksize_from_opt;
82
83 unsigned int timeout;
84 int timeout_from_opt;
85
86 off_t tsize;
87 int tsize_from_opt;
88};
89
90struct tftpd {
91 struct udp_pcb *pcb;
92 char *root;
93
94#define TFTP_MAX_XFERS 3
95 struct xfer xfers[TFTP_MAX_XFERS];
96};
97
98struct tftp_option {
99 const char *name;
100 int (*getopt)(struct xfer *, const char *);
101 int (*ackopt)(struct xfer *, char **, size_t *);
102};
103
104
105static void tftpd_recv(void *, struct udp_pcb *, struct pbuf *, ip_addr_t *, u16_t);
106
107static void tftpd_rrq(struct pbuf *, ip_addr_t *, u16_t);
108
109static void tftp_xfer_recv(void *, struct udp_pcb *, struct pbuf *, ip_addr_t *, u16_t);
110
111static void tftp_recv_ack(struct xfer *, u16_t);
112static void tftp_fillbuf(struct xfer *);
113static void tftp_send(struct xfer *);
114static void tftp_timeout(void *);
115
116static struct xfer *tftp_xfer_alloc(ip_addr_t *, u16_t);
117static int tftp_xfer_create_pcb(struct xfer *);
118static void tftp_xfer_free(struct xfer *);
119
120static int tftp_parse_filename(struct xfer *, char **, size_t *);
121static int tftp_parse_mode(struct xfer *, char **, size_t *);
122static int tftp_parse_option(struct xfer *, char **, size_t *);
123
124static int tftp_opt_blksize(struct xfer *, const char *);
125static int tftp_opt_timeout(struct xfer *, const char *);
126static int tftp_opt_tsize(struct xfer *, const char *);
127
128static char *tftp_getstr(struct xfer *, const char *, char **, size_t *);
129
130static int tftp_ack_blksize(struct xfer *, char **, size_t *);
131static int tftp_ack_timeout(struct xfer *, char **, size_t *);
132static int tftp_ack_tsize(struct xfer *, char **, size_t *);
133
134static int tftp_add_oack(char **, size_t *, const char *, const char *, ...) __attribute__((format(printf, 4, 5)));
135
136static ssize_t tftp_strnlen(char *, size_t);
137
138static int tftp_internal_error(struct xfer *);
139static int tftp_error(struct xfer *, u16_t, const char *, ...) __attribute__((format(printf, 3, 4)));
140static void tftpd_error(ip_addr_t *, u16_t, u16_t, const char *, ...) __attribute__((format(printf, 4, 5)));
141static struct pbuf *tftp_verror(u16_t, const char *, va_list);
142
143
144/* const */ int report_transient_errors = 1;
145static struct tftpd tftpd;
146
147static struct tftp_option tftp_options[] = {
148 { "blksize", tftp_opt_blksize, tftp_ack_blksize }, /* RFC 2348 */
149 { "timeout", tftp_opt_timeout, tftp_ack_timeout }, /* RFC 2349 */
150 { "tsize", tftp_opt_tsize, tftp_ack_tsize }, /* RFC 2349 */
151 { NULL, NULL, NULL }
152};
153
154
155err_t
156tftpd_init(struct netif *proxy_netif, const char *tftproot)
157{
158 size_t len;
159 err_t error;
160
161 tftpd.root = strdup(tftproot);
162 if (tftpd.root == NULL) {
163 DPRINTF0(("%s: failed to allocate tftpd.root\n", __func__));
164 return ERR_MEM;
165 }
166
167 len = strlen(tftproot);
168 if (tftpd.root[len - 1] == '/') {
169 tftpd.root[len - 1] = '\0';
170 }
171
172 tftpd.pcb = udp_new();
173 if (tftpd.pcb == NULL) {
174 DPRINTF0(("%s: failed to allocate PCB\n", __func__));
175 return ERR_MEM;
176 }
177
178 udp_recv(tftpd.pcb, tftpd_recv, NULL);
179
180 error = udp_bind(tftpd.pcb, &proxy_netif->ip_addr, TFTP_SERVER_PORT);
181 if (error != ERR_OK) {
182 DPRINTF0(("%s: failed to bind PCB\n", __func__));
183 return error;
184 }
185
186 return ERR_OK;
187}
188
189
190static void
191tftpd_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p,
192 ip_addr_t *addr, u16_t port)
193{
194 u16_t op;
195
196 LWIP_ASSERT1(pcb == tftpd.pcb);
197
198 LWIP_UNUSED_ARG(pcb); /* only in assert */
199 LWIP_UNUSED_ARG(arg);
200
201 if (pbuf_clen(p) > 1) { /* this code assumes contiguous aligned payload */
202 pbuf_free(p);
203 return;
204 }
205
206 op = ntohs(*(u16_t *)p->payload);
207 switch (op) {
208 case TFTP_RRQ:
209 tftpd_rrq(p, addr, port);
210 break;
211
212 case TFTP_WRQ:
213 tftpd_error(addr, port, TFTP_EACCESS, "Permission denied");
214 break;
215
216 default:
217 tftpd_error(addr, port, TFTP_ENOSYS, "Bad opcode %d", op);
218 break;
219 }
220
221 pbuf_free(p);
222}
223
224
225/**
226 * Parse Read Request packet and start new transfer.
227 */
228static void
229tftpd_rrq(struct pbuf *p, ip_addr_t *addr, u16_t port)
230{
231 struct xfer *xfer;
232 char *s;
233 size_t len;
234 int has_options;
235 int status;
236
237 xfer = tftp_xfer_alloc(addr, port);
238 if (xfer == NULL) {
239 return;
240 }
241
242 /* skip opcode */
243 s = (char *)p->payload + sizeof(u16_t);
244 len = p->len - sizeof(u16_t);
245
246
247 /*
248 * Parse RRQ:
249 * filename, mode, [opt1, value1, [...] ]
250 */
251 status = tftp_parse_filename(xfer, &s, &len);
252 if (status < 0) {
253 goto terminate;
254 }
255
256 status = tftp_parse_mode(xfer, &s, &len);
257 if (status < 0) {
258 goto terminate;
259 }
260
261 has_options = 0;
262 while (len > 0) {
263 status = tftp_parse_option(xfer, &s, &len);
264 if (status < 0) {
265 goto terminate;
266 }
267 has_options += status;
268 }
269
270
271 /*
272 * Create OACK packet if necessary.
273 */
274 if (has_options) {
275 xfer->oack = pbuf_alloc(PBUF_RAW, 128, PBUF_RAM);
276 if (xfer->oack != NULL) {
277 struct tftp_option *o;
278
279 ((u16_t *)xfer->oack->payload)[0] = PP_HTONS(TFTP_OACK);
280
281 s = (char *)xfer->oack->payload + sizeof(u16_t);
282 len = xfer->oack->len - sizeof(u16_t);
283
284 for (o = &tftp_options[0]; o->name != NULL; ++o) {
285 status = (*o->ackopt)(xfer, &s, &len);
286 if (status < 0) {
287 pbuf_free(xfer->oack);
288 xfer->oack = NULL;
289 break;
290 }
291 }
292
293 if (xfer->oack != NULL) {
294 Assert((u16_t)(xfer->oack->len - len) == xfer->oack->len - len);
295 pbuf_realloc(xfer->oack, (u16_t)(xfer->oack->len - len));
296 }
297 }
298 }
299
300
301 /*
302 * Create static pbuf that will be used for all data packets.
303 */
304 xfer->pbuf = pbuf_alloc(PBUF_RAW, xfer->blksize + 4, PBUF_RAM);
305 if (xfer->pbuf == NULL) {
306 tftp_internal_error(xfer);
307 goto terminate;
308 }
309 ((u16_t *)xfer->pbuf->payload)[0] = PP_HTONS(TFTP_DATA);
310
311
312 /*
313 * Finally, create PCB. Before this point any error was reported
314 * from the server port (see tftp_error() for the reason).
315 */
316 status = tftp_xfer_create_pcb(xfer);
317 if (status < 0) {
318 goto terminate;
319 }
320
321 if (xfer->oack) {
322 tftp_send(xfer);
323 }
324 else {
325 /* trigger send of the first data packet */
326 tftp_recv_ack(xfer, 0);
327 }
328
329 return;
330
331 terminate:
332 DPRINTF(("%s: terminated", __func__));
333 tftp_xfer_free(xfer);
334}
335
336
337static void
338tftp_xfer_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p,
339 ip_addr_t *addr, u16_t port)
340{
341 struct xfer *xfer = (struct xfer *)arg;
342 u16_t op;
343
344 LWIP_UNUSED_ARG(pcb); /* assert only */
345 LWIP_UNUSED_ARG(addr);
346 LWIP_UNUSED_ARG(port);
347
348 LWIP_ASSERT1(xfer->pcb == pcb);
349
350 if (p->len < 2) {
351 tftp_error(xfer, TFTP_ENOSYS, "Short packet");
352 tftp_xfer_free(xfer);
353 pbuf_free(p);
354 return;
355 }
356
357 op = ntohs(*(u16_t *)p->payload);
358 if (op == TFTP_ACK) {
359 u16_t ack;
360
361 if (p->len < 4) {
362 tftp_error(xfer, TFTP_ENOSYS, "Short packet");
363 tftp_xfer_free(xfer);
364 pbuf_free(p);
365 return;
366 }
367
368 ack = ntohs(((u16_t *)p->payload)[1]);
369 tftp_recv_ack(xfer, ack);
370 }
371 else if (op == TFTP_ERROR) {
372 tftp_xfer_free(xfer);
373 }
374 else {
375 tftp_error(xfer, TFTP_ENOSYS, "Unexpected opcode %d", op);
376 tftp_xfer_free(xfer);
377 }
378
379 pbuf_free(p);
380}
381
382
383static void
384tftp_recv_ack(struct xfer *xfer, u16_t ack)
385{
386 if (ack != (u16_t)xfer->ack) {
387 DPRINTF2(("%s: expect %u (%u), got %u\n",
388 __func__, (u16_t)xfer->ack, xfer->ack, ack));
389 return;
390 }
391
392 sys_untimeout(tftp_timeout, xfer);
393 xfer->rexmit = 0;
394
395 if (xfer->pbuf->len < xfer->blksize) {
396 DPRINTF(("%s: got final ack %u (%u)\n",
397 __func__, (u16_t)xfer->ack, xfer->ack));
398 tftp_xfer_free(xfer);
399 return;
400 }
401
402 if (xfer->oack != NULL) {
403 pbuf_free(xfer->oack);
404 xfer->oack = NULL;
405 }
406
407 ++xfer->ack;
408 tftp_fillbuf(xfer);
409 tftp_send(xfer);
410}
411
412
413static void
414tftp_send(struct xfer *xfer)
415{
416 struct pbuf *pbuf;
417
418 pbuf = xfer->oack ? xfer->oack : xfer->pbuf;
419 udp_send(xfer->pcb, pbuf);
420 sys_timeout(xfer->timeout * 1000, tftp_timeout, xfer);
421}
422
423
424static void
425tftp_timeout(void *arg)
426{
427 struct xfer *xfer = (struct xfer *)arg;
428 int maxrexmit;
429
430 maxrexmit = xfer->timeout < 60 ? 5 : 3;
431 if (++xfer->rexmit < maxrexmit) {
432 tftp_send(xfer);
433 }
434 else {
435 tftp_xfer_free(xfer);
436 }
437}
438
439
440static void
441tftp_fillbuf(struct xfer *xfer)
442{
443 ssize_t nread;
444
445 DPRINTF2(("%s: reading block %u\n", __func__, xfer->ack));
446
447 ((u16_t *)xfer->pbuf->payload)[1] = htons(xfer->ack);
448 nread = read(xfer->fd, (char *)xfer->pbuf->payload + 4, xfer->blksize);
449
450 if (nread < 0) {
451 tftp_error(xfer, TFTP_EUNDEF, "Read failed");
452 return;
453 }
454
455 pbuf_realloc(xfer->pbuf, nread + 4);
456}
457
458
459/**
460 * Find a free transfer slot (without a pcb). Record peer's IP
461 * address and port, but don't allocate a pcb yet.
462 *
463 * We delay creation of the pcb in response to the original request
464 * until the request is verified and accepted. This makes using
465 * tcpdump(8) easier, since tcpdump does not track TFTP transfers, so
466 * an error reply from a new pcb is not recognized as such and is not
467 * decoded as TFTP (see tftp_error()).
468 *
469 * If the request is rejected, the pcb remains NULL and the transfer
470 * slot remains unallocated. Since all TFTP processing happens on the
471 * lwIP thread, there's no concurrent processing, so we don't need to
472 * "lock" the transfer slot until the pcb is allocated.
473 */
474static struct xfer *
475tftp_xfer_alloc(ip_addr_t *addr, u16_t port)
476{
477 struct xfer *xfer;
478 int i;
479
480 /* Find free xfer slot */
481 xfer = NULL;
482 for (i = 0; i < TFTP_MAX_XFERS; ++i) {
483 if (tftpd.xfers[i].pcb == NULL) {
484 xfer = &tftpd.xfers[i];
485 break;
486 }
487 }
488
489 if (xfer == NULL) {
490 if (report_transient_errors) {
491 tftpd_error(addr, port, TFTP_EUNDEF,
492 "Maximum number of simultaneous connections exceeded");
493 }
494 return NULL;
495 }
496
497 ipX_addr_copy(0, xfer->peer_ip, *ip_2_ipX(addr));
498 xfer->peer_port = port;
499
500 xfer->ack = 0;
501
502 xfer->pbuf = NULL;
503 xfer->oack = NULL;
504 xfer->rexmit = 0;
505
506 xfer->blksize = 512;
507 xfer->blksize_from_opt = 0;
508
509 xfer->timeout = 1;
510 xfer->timeout_from_opt = 0;
511
512 xfer->tsize = -1;
513 xfer->tsize_from_opt = 0;
514
515 return xfer;
516}
517
518
519static int
520tftp_xfer_create_pcb(struct xfer *xfer)
521{
522 struct udp_pcb *pcb;
523 err_t error;
524
525 pcb = udp_new();
526
527 /* Bind */
528 if (pcb != NULL) {
529 error = udp_bind(pcb, ipX_2_ip(&tftpd.pcb->local_ip), 0);
530 if (error != ERR_OK) {
531 udp_remove(pcb);
532 pcb = NULL;
533 }
534 }
535
536 /* Connect */
537 if (pcb != NULL) {
538 error = udp_connect(pcb, ipX_2_ip(&xfer->peer_ip), xfer->peer_port);
539 if (error != ERR_OK) {
540 udp_remove(pcb);
541 pcb = NULL;
542 }
543 }
544
545 if (pcb == NULL) {
546 if (report_transient_errors) {
547 tftp_error(xfer, TFTP_EUNDEF, "Failed to create connection");
548 }
549 return -1;
550 }
551
552 xfer->pcb = pcb;
553 udp_recv(xfer->pcb, tftp_xfer_recv, xfer);
554
555 return 0;
556}
557
558
559static void
560tftp_xfer_free(struct xfer *xfer)
561{
562 sys_untimeout(tftp_timeout, xfer);
563
564 if (xfer->pcb != NULL) {
565 udp_remove(xfer->pcb);
566 xfer->pcb = NULL;
567 }
568
569 if (xfer->fd > 0) {
570 close(xfer->fd);
571 xfer->fd = -1;
572 }
573
574 if (xfer->oack != NULL) {
575 pbuf_free(xfer->oack);
576 xfer->oack = NULL;
577 }
578
579 if (xfer->pbuf != NULL) {
580 pbuf_free(xfer->pbuf);
581 xfer->pbuf = NULL;
582 }
583
584 if (xfer->filename != NULL) {
585 free(xfer->filename);
586 xfer->filename = NULL;
587 }
588}
589
590
591static int
592tftp_parse_filename(struct xfer *xfer, char **ps, size_t *plen)
593{
594 const char *filename;
595 struct stat st;
596 char *pathname;
597 char *s;
598 size_t len;
599 int status;
600
601 filename = tftp_getstr(xfer, "filename", ps, plen);
602 if (filename == NULL) {
603 return -1;
604 }
605
606 DPRINTF(("%s: requested file name: %s\n", __func__, filename));
607 xfer->filename = strdup(filename);
608 if (xfer->filename == NULL) {
609 return tftp_internal_error(xfer);
610 }
611
612 /* replace backslashes with forward slashes */
613 s = xfer->filename;
614 while ((s = strchr(s, '\\')) != NULL) {
615 *s++ = '/';
616 }
617
618 /* deny attempts to break out of tftp dir */
619 if (strncmp(xfer->filename, "../", 3) == 0
620 || strstr(xfer->filename, "/../") != NULL)
621 {
622 return tftp_error(xfer, TFTP_ENOENT, "Permission denied");
623 }
624
625 len = strlen(tftpd.root) + 1 /*slash*/ + strlen(xfer->filename) + 1 /*nul*/;
626 pathname = (char *)malloc(len);
627 if (pathname == NULL) {
628 return tftp_internal_error(xfer);
629 }
630
631 RTStrPrintf(pathname, len, "%s/%s", tftpd.root, xfer->filename);
632/** @todo fix RTStrPrintf because this does not currently work:
633 * status = RTStrPrintf(pathname, len, "%s/%s", tftpd.root, xfer->filename);
634 * if (status < 0) {
635 * return tftp_internal_error(xfer);
636 * }
637 */
638
639 DPRINTF(("%s: full pathname: %s\n", __func__, pathname));
640 xfer->fd = open(pathname, O_RDONLY);
641 if (xfer->fd < 0) {
642 if (errno == EPERM) {
643 return tftp_error(xfer, TFTP_ENOENT, "Permission denied");
644 }
645 else {
646 return tftp_error(xfer, TFTP_ENOENT, "File not found");
647 }
648 }
649
650 status = fstat(xfer->fd, &st);
651 if (status < 0) {
652 return tftp_internal_error(xfer);
653 }
654
655 if (!S_ISREG(st.st_mode)) {
656 return tftp_error(xfer, TFTP_ENOENT, "File not found");
657 }
658
659 xfer->tsize = st.st_size;
660 return 0;
661}
662
663
664static int
665tftp_parse_mode(struct xfer *xfer, char **ps, size_t *plen)
666{
667 const char *modename;
668
669 modename = tftp_getstr(xfer, "mode", ps, plen);
670 if (modename == NULL) {
671 return -1;
672 }
673
674 if (RTStrICmp(modename, "octet") == 0) {
675 xfer->octet = 1;
676 }
677 else if (RTStrICmp(modename, "netascii") == 0) {
678 xfer->octet = 0;
679 /* XXX: not (yet?) */
680 return tftp_error(xfer, TFTP_ENOSYS, "Mode \"netascii\" not supported");
681 }
682 else if (RTStrICmp(modename, "mail") == 0) {
683 return tftp_error(xfer, TFTP_ENOSYS, "Mode \"mail\" not supported");
684 }
685 else {
686 return tftp_error(xfer, TFTP_ENOSYS, "Unknown mode \"%s\"", modename);
687 }
688
689 return 0;
690}
691
692
693static int
694tftp_parse_option(struct xfer *xfer, char **ps, size_t *plen)
695{
696 const char *opt;
697 const char *val;
698 struct tftp_option *o;
699
700 opt = tftp_getstr(xfer, "option name", ps, plen);
701 if (opt == NULL) {
702 return -1;
703 }
704
705 if (*plen == 0) {
706 return tftp_error(xfer, TFTP_EUNDEF, "Missing option value");
707 }
708
709 val = tftp_getstr(xfer, "option value", ps, plen);
710 if (val == NULL) {
711 return -1;
712 }
713
714 /* handle option if known, ignore otherwise */
715 for (o = &tftp_options[0]; o->name != NULL; ++o) {
716 if (RTStrICmp(o->name, opt) == 0) {
717 return (*o->getopt)(xfer, val);
718 }
719 }
720
721 return 0; /* unknown option */
722}
723
724
725static int
726tftp_opt_blksize(struct xfer *xfer, const char *optval)
727{
728 char *end;
729 long blksize;
730
731 errno = 0;
732 blksize = strtol(optval, &end, 10);
733 if (errno != 0 || *end != '\0') {
734 return 0;
735 }
736
737 if (blksize < 8) {
738 return 0;
739 }
740
741 if (blksize > 1428) { /* exceeds ethernet mtu */
742 blksize = 1428;
743 }
744
745 xfer->blksize = blksize;
746 xfer->blksize_from_opt = 1;
747 return 1;
748}
749
750
751static int
752tftp_opt_timeout(struct xfer *xfer, const char *optval)
753{
754 LWIP_UNUSED_ARG(xfer);
755 LWIP_UNUSED_ARG(optval);
756 return 0;
757}
758
759
760static int
761tftp_opt_tsize(struct xfer *xfer, const char *optval)
762{
763 LWIP_UNUSED_ARG(optval); /* must be "0", but we don't check it */
764
765 if (xfer->tsize < 0) {
766 return 0;
767 }
768
769 xfer->tsize_from_opt = 1;
770 return 1;
771}
772
773
774static char *
775tftp_getstr(struct xfer *xfer, const char *msg, char **ps, size_t *plen)
776{
777 char *s;
778 ssize_t slen;
779
780 s = *ps;
781 slen = tftp_strnlen(s, *plen);
782 if (slen < 0) {
783 tftp_error(xfer, TFTP_EUNDEF, "Unterminated %s", msg);
784 return NULL;
785 }
786
787 *ps += slen + 1;
788 *plen -= slen + 1;
789
790 return s;
791}
792
793
794static int
795tftp_ack_blksize(struct xfer *xfer, char **ps, size_t *plen)
796{
797 if (!xfer->blksize_from_opt) {
798 return 0;
799 }
800
801 return tftp_add_oack(ps, plen, "blksize", "%u", xfer->blksize);
802}
803
804
805static int
806tftp_ack_timeout(struct xfer *xfer, char **ps, size_t *plen)
807{
808 if (!xfer->timeout_from_opt) {
809 return 0;
810 }
811
812 return tftp_add_oack(ps, plen, "timeout", "%u", xfer->timeout);
813}
814
815
816static int
817tftp_ack_tsize(struct xfer *xfer, char **ps, size_t *plen)
818{
819 if (!xfer->tsize_from_opt) {
820 return 0;
821 }
822
823 LWIP_ASSERT1(xfer->tsize >= 0);
824 return tftp_add_oack(ps, plen, "tsize",
825 /* XXX: FIXME: want 64 bit */
826 "%lu", (unsigned long)xfer->tsize);
827}
828
829
830static int
831tftp_add_oack(char **ps, size_t *plen,
832 const char *optname, const char *fmt, ...)
833{
834 va_list ap;
835 int sz;
836
837/** @todo Fix RTStrPrintf because this doesn't really work.
838 * sz = RTStrPrintf(*ps, *plen, "%s", optname);
839 * if (sz < 0 || (size_t)sz >= *plen) {
840 * return -1;
841 * } */
842 sz = (int)RTStrPrintf(*ps, *plen, "%s", optname);
843 if (/*sz < 0 ||*/ (size_t)sz >= *plen) {
844 return -1;
845 }
846
847 ++sz; /* for nul byte */
848 *ps += sz;
849 *plen -= sz;
850
851 va_start(ap, fmt);
852 sz = vsnprintf(*ps, *plen, fmt, ap);
853 va_end(ap);
854 if (sz < 0 || (size_t)sz >= *plen) {
855 return -1;
856 }
857
858 ++sz; /* for nul byte */
859 *ps += sz;
860 *plen -= sz;
861
862 return 0;
863}
864
865
866static ssize_t
867tftp_strnlen(char *buf, size_t bufsize)
868{
869 void *end;
870
871 end = memchr(buf, '\0', bufsize);
872 if (end == NULL) {
873 return -1;
874 }
875
876 return (char *)end - buf;
877}
878
879
880static int
881tftp_internal_error(struct xfer *xfer)
882{
883 if (report_transient_errors) {
884 tftp_error(xfer, TFTP_EUNDEF, "Internal error");
885 }
886 return -1;
887}
888
889
890/**
891 * Send an error packet to the peer.
892 *
893 * PCB may not be created yet in which case send the error packet from
894 * the TFTP server port (*).
895 *
896 * (*) We delay creation of the PCB in response to the original
897 * request until the request is verified and accepted. This makes
898 * using tcpdump(8) easier, since tcpdump does not track TFTP
899 * transfers, so an error reply from a new PCB is not recognized as
900 * such and is not decoded as TFTP.
901 *
902 * Always returns -1 for callers to reuse.
903 */
904static int
905tftp_error(struct xfer *xfer, u16_t error, const char *fmt, ...)
906{
907 va_list ap;
908 struct pbuf *q;
909
910 LWIP_ASSERT1(xfer != NULL);
911
912 va_start(ap, fmt);
913 q = tftp_verror(error, fmt, ap);
914 va_end(ap);
915
916 if (q == NULL) {
917 return -1;
918 }
919
920 if (xfer->pcb != NULL) {
921 udp_send(xfer->pcb, q);
922 }
923 else {
924 udp_sendto(tftpd.pcb, q, ipX_2_ip(&xfer->peer_ip), xfer->peer_port);
925 }
926
927 pbuf_free(q);
928 return -1;
929}
930
931
932/**
933 * Send an error packet from TFTP server port to the specified peer.
934 */
935static void
936tftpd_error(ip_addr_t *addr, u16_t port, u16_t error, const char *fmt, ...)
937{
938 va_list ap;
939 struct pbuf *q;
940
941 va_start(ap, fmt);
942 q = tftp_verror(error, fmt, ap);
943 va_end(ap);
944
945 if (q != NULL) {
946 udp_sendto(tftpd.pcb, q, addr, port);
947 pbuf_free(q);
948 }
949}
950
951
952/**
953 * Create ERROR pbuf with formatted error message.
954 */
955static struct pbuf *
956tftp_verror(u16_t error, const char *fmt, va_list ap)
957{
958 struct tftp_error {
959 u16_t opcode; /* TFTP_ERROR */
960 u16_t errcode;
961 char errmsg[512];
962 };
963
964 struct pbuf *p;
965 struct tftp_error *errpkt;
966 int msgsz;
967
968 p = pbuf_alloc(PBUF_TRANSPORT, sizeof(*errpkt), PBUF_RAM);
969 if (p == NULL) {
970 return NULL;
971 }
972
973 errpkt = (struct tftp_error *)p->payload;
974 errpkt->opcode = PP_HTONS(TFTP_ERROR);
975 errpkt->errcode = htons(error);
976
977 msgsz = vsnprintf(errpkt->errmsg, sizeof(errpkt->errmsg), fmt, ap);
978 if (msgsz < 0) {
979 errpkt->errmsg[0] = '\0';
980 msgsz = 1;
981 }
982 else if ((size_t)msgsz < sizeof(errpkt->errmsg)) {
983 ++msgsz; /* for nul byte */
984 }
985 else {
986 msgsz = sizeof(errpkt->errmsg); /* truncated, includes nul byte */
987 }
988
989 pbuf_realloc(p, sizeof(*errpkt) - sizeof(errpkt->errmsg) + msgsz);
990 return p;
991}
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