Fix lurking bug exposed by r18687
[reactos.git] / reactos / services / dhcp / options.c
1 /* $OpenBSD: options.c,v 1.15 2004/12/26 03:17:07 deraadt Exp $ */
2
3 /* DHCP options parsing and reassembly. */
4
5 /*
6 * Copyright (c) 1995, 1996, 1997, 1998 The Internet Software Consortium.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of The Internet Software Consortium nor the names
19 * of its contributors may be used to endorse or promote products derived
20 * from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
23 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
24 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
25 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
26 * DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
27 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
29 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
30 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
31 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
32 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
33 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 * This software has been written for the Internet Software Consortium
37 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
38 * Enterprises. To learn more about the Internet Software Consortium,
39 * see ``http://www.vix.com/isc''. To learn more about Vixie
40 * Enterprises, see ``http://www.vix.com''.
41 */
42
43 #include <ctype.h>
44 #include <string.h>
45
46 #define DHCP_OPTION_DATA
47 #include "rosdhcp.h"
48 #include "dhcpd.h"
49
50 int bad_options = 0;
51 int bad_options_max = 5;
52
53 void parse_options(struct packet *);
54 void parse_option_buffer(struct packet *, unsigned char *, int);
55 int store_options(unsigned char *, int, struct tree_cache **,
56 unsigned char *, int, int, int, int);
57
58
59 /*
60 * Parse all available options out of the specified packet.
61 */
62 void
63 parse_options(struct packet *packet)
64 {
65 /* Initially, zero all option pointers. */
66 memset(packet->options, 0, sizeof(packet->options));
67
68 /* If we don't see the magic cookie, there's nothing to parse. */
69 if (memcmp(packet->raw->options, DHCP_OPTIONS_COOKIE, 4)) {
70 packet->options_valid = 0;
71 return;
72 }
73
74 /*
75 * Go through the options field, up to the end of the packet or
76 * the End field.
77 */
78 parse_option_buffer(packet, &packet->raw->options[4],
79 packet->packet_length - DHCP_FIXED_NON_UDP - 4);
80
81 /*
82 * If we parsed a DHCP Option Overload option, parse more
83 * options out of the buffer(s) containing them.
84 */
85 if (packet->options_valid &&
86 packet->options[DHO_DHCP_OPTION_OVERLOAD].data) {
87 if (packet->options[DHO_DHCP_OPTION_OVERLOAD].data[0] & 1)
88 parse_option_buffer(packet,
89 (unsigned char *)packet->raw->file,
90 sizeof(packet->raw->file));
91 if (packet->options[DHO_DHCP_OPTION_OVERLOAD].data[0] & 2)
92 parse_option_buffer(packet,
93 (unsigned char *)packet->raw->sname,
94 sizeof(packet->raw->sname));
95 }
96 }
97
98 /*
99 * Parse options out of the specified buffer, storing addresses of
100 * option values in packet->options and setting packet->options_valid if
101 * no errors are encountered.
102 */
103 void
104 parse_option_buffer(struct packet *packet,
105 unsigned char *buffer, int length)
106 {
107 unsigned char *s, *t, *end = buffer + length;
108 int len, code;
109
110 for (s = buffer; *s != DHO_END && s < end; ) {
111 code = s[0];
112
113 /* Pad options don't have a length - just skip them. */
114 if (code == DHO_PAD) {
115 s++;
116 continue;
117 }
118 if (s + 2 > end) {
119 len = 65536;
120 goto bogus;
121 }
122
123 /*
124 * All other fields (except end, see above) have a
125 * one-byte length.
126 */
127 len = s[1];
128
129 /*
130 * If the length is outrageous, silently skip the rest,
131 * and mark the packet bad. Unfortunately some crappy
132 * dhcp servers always seem to give us garbage on the
133 * end of a packet. so rather than keep refusing, give
134 * up and try to take one after seeing a few without
135 * anything good.
136 */
137 if (s + len + 2 > end) {
138 bogus:
139 bad_options++;
140 warning("option %s (%d) %s.",
141 dhcp_options[code].name, len,
142 "larger than buffer");
143 if (bad_options == bad_options_max) {
144 packet->options_valid = 1;
145 bad_options = 0;
146 warning("Many bogus options seen in offers. "
147 "Taking this offer in spite of bogus "
148 "options - hope for the best!");
149 } else {
150 warning("rejecting bogus offer.");
151 packet->options_valid = 0;
152 }
153 return;
154 }
155 /*
156 * If we haven't seen this option before, just make
157 * space for it and copy it there.
158 */
159 if (!packet->options[code].data) {
160 if (!(t = calloc(1, len + 1)))
161 error("Can't allocate storage for option %s.",
162 dhcp_options[code].name);
163 /*
164 * Copy and NUL-terminate the option (in case
165 * it's an ASCII string.
166 */
167 memcpy(t, &s[2], len);
168 t[len] = 0;
169 packet->options[code].len = len;
170 packet->options[code].data = t;
171 } else {
172 /*
173 * If it's a repeat, concatenate it to whatever
174 * we last saw. This is really only required
175 * for clients, but what the heck...
176 */
177 t = calloc(1, len + packet->options[code].len + 1);
178 if (!t)
179 error("Can't expand storage for option %s.",
180 dhcp_options[code].name);
181 memcpy(t, packet->options[code].data,
182 packet->options[code].len);
183 memcpy(t + packet->options[code].len,
184 &s[2], len);
185 packet->options[code].len += len;
186 t[packet->options[code].len] = 0;
187 free(packet->options[code].data);
188 packet->options[code].data = t;
189 }
190 s += len + 2;
191 }
192 packet->options_valid = 1;
193 }
194
195 /*
196 * cons options into a big buffer, and then split them out into the
197 * three separate buffers if needed. This allows us to cons up a set of
198 * vendor options using the same routine.
199 */
200 int
201 cons_options(struct packet *inpacket, struct dhcp_packet *outpacket,
202 int mms, struct tree_cache **options,
203 int overload, /* Overload flags that may be set. */
204 int terminate, int bootpp, u_int8_t *prl, int prl_len)
205 {
206 unsigned char priority_list[300], buffer[4096];
207 int priority_len, main_buffer_size, mainbufix, bufix;
208 int option_size, length;
209
210 /*
211 * If the client has provided a maximum DHCP message size, use
212 * that; otherwise, if it's BOOTP, only 64 bytes; otherwise use
213 * up to the minimum IP MTU size (576 bytes).
214 *
215 * XXX if a BOOTP client specifies a max message size, we will
216 * honor it.
217 */
218 if (!mms &&
219 inpacket &&
220 inpacket->options[DHO_DHCP_MAX_MESSAGE_SIZE].data &&
221 (inpacket->options[DHO_DHCP_MAX_MESSAGE_SIZE].len >=
222 sizeof(u_int16_t)))
223 mms = getUShort(
224 inpacket->options[DHO_DHCP_MAX_MESSAGE_SIZE].data);
225
226 if (mms)
227 main_buffer_size = mms - DHCP_FIXED_LEN;
228 else if (bootpp)
229 main_buffer_size = 64;
230 else
231 main_buffer_size = 576 - DHCP_FIXED_LEN;
232
233 if (main_buffer_size > sizeof(buffer))
234 main_buffer_size = sizeof(buffer);
235
236 /* Preload the option priority list with mandatory options. */
237 priority_len = 0;
238 priority_list[priority_len++] = DHO_DHCP_MESSAGE_TYPE;
239 priority_list[priority_len++] = DHO_DHCP_SERVER_IDENTIFIER;
240 priority_list[priority_len++] = DHO_DHCP_LEASE_TIME;
241 priority_list[priority_len++] = DHO_DHCP_MESSAGE;
242
243 /*
244 * If the client has provided a list of options that it wishes
245 * returned, use it to prioritize. Otherwise, prioritize based
246 * on the default priority list.
247 */
248 if (inpacket &&
249 inpacket->options[DHO_DHCP_PARAMETER_REQUEST_LIST].data) {
250 int prlen =
251 inpacket->options[DHO_DHCP_PARAMETER_REQUEST_LIST].len;
252 if (prlen + priority_len > sizeof(priority_list))
253 prlen = sizeof(priority_list) - priority_len;
254
255 memcpy(&priority_list[priority_len],
256 inpacket->options[DHO_DHCP_PARAMETER_REQUEST_LIST].data,
257 prlen);
258 priority_len += prlen;
259 prl = priority_list;
260 } else if (prl) {
261 if (prl_len + priority_len > sizeof(priority_list))
262 prl_len = sizeof(priority_list) - priority_len;
263
264 memcpy(&priority_list[priority_len], prl, prl_len);
265 priority_len += prl_len;
266 prl = priority_list;
267 } else {
268 memcpy(&priority_list[priority_len],
269 dhcp_option_default_priority_list,
270 sizeof_dhcp_option_default_priority_list);
271 priority_len += sizeof_dhcp_option_default_priority_list;
272 }
273
274 /* Copy the options into the big buffer... */
275 option_size = store_options(
276 buffer,
277 (main_buffer_size - 7 + ((overload & 1) ? DHCP_FILE_LEN : 0) +
278 ((overload & 2) ? DHCP_SNAME_LEN : 0)),
279 options, priority_list, priority_len, main_buffer_size,
280 (main_buffer_size + ((overload & 1) ? DHCP_FILE_LEN : 0)),
281 terminate);
282
283 /* Put the cookie up front... */
284 memcpy(outpacket->options, DHCP_OPTIONS_COOKIE, 4);
285 mainbufix = 4;
286
287 /*
288 * If we're going to have to overload, store the overload option
289 * at the beginning. If we can, though, just store the whole
290 * thing in the packet's option buffer and leave it at that.
291 */
292 if (option_size <= main_buffer_size - mainbufix) {
293 memcpy(&outpacket->options[mainbufix],
294 buffer, option_size);
295 mainbufix += option_size;
296 if (mainbufix < main_buffer_size)
297 outpacket->options[mainbufix++] = DHO_END;
298 length = DHCP_FIXED_NON_UDP + mainbufix;
299 } else {
300 outpacket->options[mainbufix++] = DHO_DHCP_OPTION_OVERLOAD;
301 outpacket->options[mainbufix++] = 1;
302 if (option_size >
303 main_buffer_size - mainbufix + DHCP_FILE_LEN)
304 outpacket->options[mainbufix++] = 3;
305 else
306 outpacket->options[mainbufix++] = 1;
307
308 memcpy(&outpacket->options[mainbufix],
309 buffer, main_buffer_size - mainbufix);
310 bufix = main_buffer_size - mainbufix;
311 length = DHCP_FIXED_NON_UDP + mainbufix;
312 if (overload & 1) {
313 if (option_size - bufix <= DHCP_FILE_LEN) {
314 memcpy(outpacket->file,
315 &buffer[bufix], option_size - bufix);
316 mainbufix = option_size - bufix;
317 if (mainbufix < DHCP_FILE_LEN)
318 outpacket->file[mainbufix++] = (char)DHO_END;
319 while (mainbufix < DHCP_FILE_LEN)
320 outpacket->file[mainbufix++] = (char)DHO_PAD;
321 } else {
322 memcpy(outpacket->file,
323 &buffer[bufix], DHCP_FILE_LEN);
324 bufix += DHCP_FILE_LEN;
325 }
326 }
327 if ((overload & 2) && option_size < bufix) {
328 memcpy(outpacket->sname,
329 &buffer[bufix], option_size - bufix);
330
331 mainbufix = option_size - bufix;
332 if (mainbufix < DHCP_SNAME_LEN)
333 outpacket->file[mainbufix++] = (char)DHO_END;
334 while (mainbufix < DHCP_SNAME_LEN)
335 outpacket->file[mainbufix++] = (char)DHO_PAD;
336 }
337 }
338 return (length);
339 }
340
341 /*
342 * Store all the requested options into the requested buffer.
343 */
344 int
345 store_options(unsigned char *buffer, int buflen, struct tree_cache **options,
346 unsigned char *priority_list, int priority_len, int first_cutoff,
347 int second_cutoff, int terminate)
348 {
349 int bufix = 0, option_stored[256], i, ix, tto;
350
351 /* Zero out the stored-lengths array. */
352 memset(option_stored, 0, sizeof(option_stored));
353
354 /*
355 * Copy out the options in the order that they appear in the
356 * priority list...
357 */
358 for (i = 0; i < priority_len; i++) {
359 /* Code for next option to try to store. */
360 int code = priority_list[i];
361 int optstart;
362
363 /*
364 * Number of bytes left to store (some may already have
365 * been stored by a previous pass).
366 */
367 int length;
368
369 /* If no data is available for this option, skip it. */
370 if (!options[code]) {
371 continue;
372 }
373
374 /*
375 * The client could ask for things that are mandatory,
376 * in which case we should avoid storing them twice...
377 */
378 if (option_stored[code])
379 continue;
380 option_stored[code] = 1;
381
382 /* We should now have a constant length for the option. */
383 length = options[code]->len;
384
385 /* Do we add a NUL? */
386 if (terminate && dhcp_options[code].format[0] == 't') {
387 length++;
388 tto = 1;
389 } else
390 tto = 0;
391
392 /* Try to store the option. */
393
394 /*
395 * If the option's length is more than 255, we must
396 * store it in multiple hunks. Store 255-byte hunks
397 * first. However, in any case, if the option data will
398 * cross a buffer boundary, split it across that
399 * boundary.
400 */
401 ix = 0;
402
403 optstart = bufix;
404 while (length) {
405 unsigned char incr = length > 255 ? 255 : length;
406
407 /*
408 * If this hunk of the buffer will cross a
409 * boundary, only go up to the boundary in this
410 * pass.
411 */
412 if (bufix < first_cutoff &&
413 bufix + incr > first_cutoff)
414 incr = first_cutoff - bufix;
415 else if (bufix < second_cutoff &&
416 bufix + incr > second_cutoff)
417 incr = second_cutoff - bufix;
418
419 /*
420 * If this option is going to overflow the
421 * buffer, skip it.
422 */
423 if (bufix + 2 + incr > buflen) {
424 bufix = optstart;
425 break;
426 }
427
428 /* Everything looks good - copy it in! */
429 buffer[bufix] = code;
430 buffer[bufix + 1] = incr;
431 if (tto && incr == length) {
432 memcpy(buffer + bufix + 2,
433 options[code]->value + ix, incr - 1);
434 buffer[bufix + 2 + incr - 1] = 0;
435 } else
436 memcpy(buffer + bufix + 2,
437 options[code]->value + ix, incr);
438 length -= incr;
439 ix += incr;
440 bufix += 2 + incr;
441 }
442 }
443 return (bufix);
444 }
445
446 /*
447 * Format the specified option so that a human can easily read it.
448 */
449 char *
450 pretty_print_option(unsigned int code, unsigned char *data, int len,
451 int emit_commas, int emit_quotes)
452 {
453 static char optbuf[32768]; /* XXX */
454 int hunksize = 0, numhunk = -1, numelem = 0;
455 char fmtbuf[32], *op = optbuf;
456 int i, j, k, opleft = sizeof(optbuf);
457 unsigned char *dp = data;
458 struct in_addr foo;
459 char comma;
460
461 /* Code should be between 0 and 255. */
462 if (code > 255)
463 error("pretty_print_option: bad code %d", code);
464
465 if (emit_commas)
466 comma = ',';
467 else
468 comma = ' ';
469
470 /* Figure out the size of the data. */
471 for (i = 0; dhcp_options[code].format[i]; i++) {
472 if (!numhunk) {
473 warning("%s: Excess information in format string: %s",
474 dhcp_options[code].name,
475 &(dhcp_options[code].format[i]));
476 break;
477 }
478 numelem++;
479 fmtbuf[i] = dhcp_options[code].format[i];
480 switch (dhcp_options[code].format[i]) {
481 case 'A':
482 --numelem;
483 fmtbuf[i] = 0;
484 numhunk = 0;
485 break;
486 case 'X':
487 for (k = 0; k < len; k++)
488 if (!isascii(data[k]) ||
489 !isprint(data[k]))
490 break;
491 if (k == len) {
492 fmtbuf[i] = 't';
493 numhunk = -2;
494 } else {
495 fmtbuf[i] = 'x';
496 hunksize++;
497 comma = ':';
498 numhunk = 0;
499 }
500 fmtbuf[i + 1] = 0;
501 break;
502 case 't':
503 fmtbuf[i] = 't';
504 fmtbuf[i + 1] = 0;
505 numhunk = -2;
506 break;
507 case 'I':
508 case 'l':
509 case 'L':
510 hunksize += 4;
511 break;
512 case 's':
513 case 'S':
514 hunksize += 2;
515 break;
516 case 'b':
517 case 'B':
518 case 'f':
519 hunksize++;
520 break;
521 case 'e':
522 break;
523 default:
524 warning("%s: garbage in format string: %s",
525 dhcp_options[code].name,
526 &(dhcp_options[code].format[i]));
527 break;
528 }
529 }
530
531 /* Check for too few bytes... */
532 if (hunksize > len) {
533 warning("%s: expecting at least %d bytes; got %d",
534 dhcp_options[code].name, hunksize, len);
535 return ("<error>");
536 }
537 /* Check for too many bytes... */
538 if (numhunk == -1 && hunksize < len)
539 warning("%s: %d extra bytes",
540 dhcp_options[code].name, len - hunksize);
541
542 /* If this is an array, compute its size. */
543 if (!numhunk)
544 numhunk = len / hunksize;
545 /* See if we got an exact number of hunks. */
546 if (numhunk > 0 && numhunk * hunksize < len)
547 warning("%s: %d extra bytes at end of array",
548 dhcp_options[code].name, len - numhunk * hunksize);
549
550 /* A one-hunk array prints the same as a single hunk. */
551 if (numhunk < 0)
552 numhunk = 1;
553
554 /* Cycle through the array (or hunk) printing the data. */
555 for (i = 0; i < numhunk; i++) {
556 for (j = 0; j < numelem; j++) {
557 int opcount;
558 switch (fmtbuf[j]) {
559 case 't':
560 if (emit_quotes) {
561 *op++ = '"';
562 opleft--;
563 }
564 for (; dp < data + len; dp++) {
565 if (!isascii(*dp) ||
566 !isprint(*dp)) {
567 if (dp + 1 != data + len ||
568 *dp != 0) {
569 snprintf(op, opleft,
570 "\\%03o", *dp);
571 op += 4;
572 opleft -= 4;
573 }
574 } else if (*dp == '"' ||
575 *dp == '\'' ||
576 *dp == '$' ||
577 *dp == '`' ||
578 *dp == '\\') {
579 *op++ = '\\';
580 *op++ = *dp;
581 opleft -= 2;
582 } else {
583 *op++ = *dp;
584 opleft--;
585 }
586 }
587 if (emit_quotes) {
588 *op++ = '"';
589 opleft--;
590 }
591
592 *op = 0;
593 break;
594 case 'I':
595 foo.s_addr = htonl(getULong(dp));
596 strncpy(op, inet_ntoa(foo), opleft - 1);
597 op[opleft - 1] = ANSI_NULL;
598 opcount = strlen(op);
599 if (opcount >= opleft)
600 goto toobig;
601 opleft -= opcount;
602 dp += 4;
603 break;
604 case 'l':
605 opcount = snprintf(op, opleft, "%ld",
606 (long)getLong(dp));
607 if (opcount >= opleft || opcount == -1)
608 goto toobig;
609 opleft -= opcount;
610 dp += 4;
611 break;
612 case 'L':
613 opcount = snprintf(op, opleft, "%ld",
614 (unsigned long)getULong(dp));
615 if (opcount >= opleft || opcount == -1)
616 goto toobig;
617 opleft -= opcount;
618 dp += 4;
619 break;
620 case 's':
621 opcount = snprintf(op, opleft, "%d",
622 getShort(dp));
623 if (opcount >= opleft || opcount == -1)
624 goto toobig;
625 opleft -= opcount;
626 dp += 2;
627 break;
628 case 'S':
629 opcount = snprintf(op, opleft, "%d",
630 getUShort(dp));
631 if (opcount >= opleft || opcount == -1)
632 goto toobig;
633 opleft -= opcount;
634 dp += 2;
635 break;
636 case 'b':
637 opcount = snprintf(op, opleft, "%d",
638 *(char *)dp++);
639 if (opcount >= opleft || opcount == -1)
640 goto toobig;
641 opleft -= opcount;
642 break;
643 case 'B':
644 opcount = snprintf(op, opleft, "%d", *dp++);
645 if (opcount >= opleft || opcount == -1)
646 goto toobig;
647 opleft -= opcount;
648 break;
649 case 'x':
650 opcount = snprintf(op, opleft, "%x", *dp++);
651 if (opcount >= opleft || opcount == -1)
652 goto toobig;
653 opleft -= opcount;
654 break;
655 case 'f':
656 opcount = (size_t) strncpy(op, *dp++ ? "true" : "false", opleft - 1);
657 op[opleft - 1] = ANSI_NULL;
658 if (opcount >= opleft)
659 goto toobig;
660 opleft -= opcount;
661 break;
662 default:
663 warning("Unexpected format code %c", fmtbuf[j]);
664 }
665 op += strlen(op);
666 opleft -= strlen(op);
667 if (opleft < 1)
668 goto toobig;
669 if (j + 1 < numelem && comma != ':') {
670 *op++ = ' ';
671 opleft--;
672 }
673 }
674 if (i + 1 < numhunk) {
675 *op++ = comma;
676 opleft--;
677 }
678 if (opleft < 1)
679 goto toobig;
680
681 }
682 return (optbuf);
683 toobig:
684 warning("dhcp option too large");
685 return ("<error>");
686 }
687
688 void
689 do_packet(struct interface_info *interface, struct dhcp_packet *packet,
690 int len, unsigned int from_port, struct iaddr from, struct hardware *hfrom)
691 {
692 struct packet tp;
693 int i;
694
695 if (packet->hlen > sizeof(packet->chaddr)) {
696 note("Discarding packet with invalid hlen.");
697 return;
698 }
699
700 memset(&tp, 0, sizeof(tp));
701 tp.raw = packet;
702 tp.packet_length = len;
703 tp.client_port = from_port;
704 tp.client_addr = from;
705 tp.interface = interface;
706 tp.haddr = hfrom;
707
708 parse_options(&tp);
709 if (tp.options_valid &&
710 tp.options[DHO_DHCP_MESSAGE_TYPE].data)
711 tp.packet_type = tp.options[DHO_DHCP_MESSAGE_TYPE].data[0];
712 if (tp.packet_type)
713 dhcp(&tp);
714 else
715 bootp(&tp);
716
717 /* Free the data associated with the options. */
718 for (i = 0; i < 256; i++)
719 if (tp.options[i].len && tp.options[i].data)
720 free(tp.options[i].data);
721 }