about summary refs log tree commit diff
path: root/resolv/res_comp.c
blob: 7da1c3e0f6b232787387e3241e9f563cfc834725 (plain) (blame)
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
/*
 * ++Copyright++ 1985, 1993
 * -
 * Copyright (c) 1985, 1993
 *    The Regents of the University of California.  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 by the University of
 * 	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 * -
 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies, and that
 * the name of Digital Equipment Corporation not be used in advertising or
 * publicity pertaining to distribution of the document or software without
 * specific, written prior permission.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 * -
 * --Copyright--
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)res_comp.c	8.1 (Berkeley) 6/4/93";
static char rcsid[] = "$Id$";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/param.h>
#include <netinet/in.h>
#include <arpa/nameser.h>

#include <stdio.h>
#include <resolv.h>
#include <ctype.h>

#if defined(BSD) && (BSD >= 199103)
# include <unistd.h>
# include <string.h>
#else
# include "../conf/portability.h"
#endif

static int	dn_find __P((u_char *exp_dn, u_char *msg,
			     u_char **dnptrs, u_char **lastdnptr));

/*
 * Expand compressed domain name 'comp_dn' to full domain name.
 * 'msg' is a pointer to the begining of the message,
 * 'eomorig' points to the first location after the message,
 * 'exp_dn' is a pointer to a buffer of size 'length' for the result.
 * Return size of compressed name or -1 if there was an error.
 */
int
dn_expand(msg, eomorig, comp_dn, exp_dn, length)
	const u_char *msg, *eomorig, *comp_dn;
	char *exp_dn;
	int length;
{
	register const u_char *cp;
	register char *dn;
	register int n, c;
	char *eom;
	int len = -1, checked = 0;

	dn = exp_dn;
	cp = comp_dn;
	eom = exp_dn + length;
	/*
	 * fetch next label in domain name
	 */
	while (n = *cp++) {
		/*
		 * Check for indirection
		 */
		switch (n & INDIR_MASK) {
		case 0:
			if (dn != exp_dn) {
				if (dn >= eom)
					return (-1);
				*dn++ = '.';
			}
			if (dn+n >= eom)
				return (-1);
			checked += n + 1;
			while (--n >= 0) {
				if (((c = *cp++) == '.') || (c == '\\')) {
					if (dn + n + 2 >= eom)
						return (-1);
					*dn++ = '\\';
				}
				*dn++ = c;
				if (cp >= eomorig)	/* out of range */
					return (-1);
			}
			break;

		case INDIR_MASK:
			if (len < 0)
				len = cp - comp_dn + 1;
			cp = msg + (((n & 0x3f) << 8) | (*cp & 0xff));
			if (cp < msg || cp >= eomorig)	/* out of range */
				return (-1);
			checked += 2;
			/*
			 * Check for loops in the compressed name;
			 * if we've looked at the whole message,
			 * there must be a loop.
			 */
			if (checked >= eomorig - msg)
				return (-1);
			break;

		default:
			return (-1);			/* flag error */
		}
	}
	*dn = '\0';
	if (len < 0)
		len = cp - comp_dn;
	return (len);
}

/*
 * Compress domain name 'exp_dn' into 'comp_dn'.
 * Return the size of the compressed name or -1.
 * 'length' is the size of the array pointed to by 'comp_dn'.
 * 'dnptrs' is a list of pointers to previous compressed names. dnptrs[0]
 * is a pointer to the beginning of the message. The list ends with NULL.
 * 'lastdnptr' is a pointer to the end of the arrary pointed to
 * by 'dnptrs'. Side effect is to update the list of pointers for
 * labels inserted into the message as we compress the name.
 * If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
 * is NULL, we don't update the list.
 */
int
dn_comp(exp_dn, comp_dn, length, dnptrs, lastdnptr)
	const char *exp_dn;
	u_char *comp_dn, **dnptrs, **lastdnptr;
	int length;
{
	register u_char *cp, *dn;
	register int c, l;
	u_char **cpp, **lpp, *sp, *eob;
	u_char *msg;

	dn = (u_char *)exp_dn;
	cp = comp_dn;
	eob = cp + length;
	lpp = cpp = NULL;
	if (dnptrs != NULL) {
		if ((msg = *dnptrs++) != NULL) {
			for (cpp = dnptrs; *cpp != NULL; cpp++)
				;
			lpp = cpp;	/* end of list to search */
		}
	} else
		msg = NULL;
	for (c = *dn++; c != '\0'; ) {
		/* look to see if we can use pointers */
		if (msg != NULL) {
			if ((l = dn_find(dn-1, msg, dnptrs, lpp)) >= 0) {
				if (cp+1 >= eob)
					return (-1);
				*cp++ = (l >> 8) | INDIR_MASK;
				*cp++ = l % 256;
				return (cp - comp_dn);
			}
			/* not found, save it */
			if (lastdnptr != NULL && cpp < lastdnptr-1) {
				*cpp++ = cp;
				*cpp = NULL;
			}
		}
		sp = cp++;	/* save ptr to length byte */
		do {
			if (c == '.') {
				c = *dn++;
				break;
			}
			if (c == '\\') {
				if ((c = *dn++) == '\0')
					break;
			}
			if (cp >= eob) {
				if (msg != NULL)
					*lpp = NULL;
				return (-1);
			}
			*cp++ = c;
		} while ((c = *dn++) != '\0');
		/* catch trailing '.'s but not '..' */
		if ((l = cp - sp - 1) == 0 && c == '\0') {
			cp--;
			break;
		}
		if (l <= 0 || l > MAXLABEL) {
			if (msg != NULL)
				*lpp = NULL;
			return (-1);
		}
		*sp = l;
	}
	if (cp >= eob) {
		if (msg != NULL)
			*lpp = NULL;
		return (-1);
	}
	*cp++ = '\0';
	return (cp - comp_dn);
}

/*
 * Skip over a compressed domain name. Return the size or -1.
 */
int
__dn_skipname(comp_dn, eom)
	const u_char *comp_dn, *eom;
{
	register const u_char *cp;
	register int n;

	cp = comp_dn;
	while (cp < eom && (n = *cp++)) {
		/*
		 * check for indirection
		 */
		switch (n & INDIR_MASK) {
		case 0:			/* normal case, n == len */
			cp += n;
			continue;
		case INDIR_MASK:	/* indirection */
			cp++;
			break;
		default:		/* illegal type */
			return (-1);
		}
		break;
	}
	if (cp > eom)
		return (-1);
	return (cp - comp_dn);
}

static int
mklower(ch)
	register int ch;
{
	if (isascii(ch) && isupper(ch))
		return (tolower(ch));
	return (ch);
}

/*
 * Search for expanded name from a list of previously compressed names.
 * Return the offset from msg if found or -1.
 * dnptrs is the pointer to the first name on the list,
 * not the pointer to the start of the message.
 */
static int
dn_find(exp_dn, msg, dnptrs, lastdnptr)
	u_char *exp_dn, *msg;
	u_char **dnptrs, **lastdnptr;
{
	register u_char *dn, *cp, **cpp;
	register int n;
	u_char *sp;

	for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
		dn = exp_dn;
		sp = cp = *cpp;
		while (n = *cp++) {
			/*
			 * check for indirection
			 */
			switch (n & INDIR_MASK) {
			case 0:		/* normal case, n == len */
				while (--n >= 0) {
					if (*dn == '.')
						goto next;
					if (*dn == '\\')
						dn++;
					if (mklower(*dn++) != mklower(*cp++))
						goto next;
				}
				if ((n = *dn++) == '\0' && *cp == '\0')
					return (sp - msg);
				if (n == '.')
					continue;
				goto next;

			case INDIR_MASK:	/* indirection */
				cp = msg + (((n & 0x3f) << 8) | *cp);
				break;

			default:	/* illegal type */
				return (-1);
			}
		}
		if (*dn == '\0')
			return (sp - msg);
	next:	;
	}
	return (-1);
}

/*
 * Verify that a domain name uses an acceptable character set.
 */

/*
 * Note the conspicuous absence of ctype macros in these definitions.  On
 * non-ASCII hosts, we can't depend on string literals or ctype macros to
 * tell us anything about network-format data.  The rest of the BIND system
 * is not careful about this, but for some reason, we're doing it right here.
 */
#define PERIOD 0x2e
#define	hyphenchar(c) ((c) == 0x2d)
#define bslashchar(c) ((c) == 0x5c)
#define periodchar(c) ((c) == PERIOD)
#define asterchar(c) ((c) == 0x2a)
#define alphachar(c) (((c) >= 0x41 && (c) <= 0x5a) \
		   || ((c) >= 0x61 && (c) <= 0x7a))
#define digitchar(c) ((c) >= 0x30 && (c) <= 0x39)

#define borderchar(c) (alphachar(c) || digitchar(c))
#define middlechar(c) (borderchar(c) || hyphenchar(c))
#define	domainchar(c) ((c) > 0x20 && (c) < 0x7f)

int
res_hnok(dn)
	const char *dn;
{
	int ppch = '\0', pch = PERIOD, ch = *dn++;

	while (ch != '\0') {
		int nch = *dn++;

		if (periodchar(ch)) {
			/* NULL */;
		} else if (periodchar(pch)) {
			if (!borderchar(ch))
				return (0);
		} else if (periodchar(nch) || nch == '\0') {
			if (!borderchar(ch))
				return (0);
		} else {
			if (!middlechar(ch))
				return (0);
		}
		ppch = pch, pch = ch, ch = nch;
	}
	return (1);
}

/*
 * hostname-like (A, MX, WKS) owners can have "*" as their first label
 * but must otherwise be as a host name.
 */
int
res_ownok(dn)
	const char *dn;
{
	if (asterchar(dn[0]) && periodchar(dn[1]))
		dn += 2;
	return (res_hnok(dn));
}

/*
 * SOA RNAMEs and RP RNAMEs can have any printable character in their first
 * label, but the rest of the name has to look like a host name.
 */
int
res_mailok(dn)
	const char *dn;
{
	int ch, escaped = 0;

	/* "." is a valid missing representation */
	if (*dn == '\0')
		return(1);

	/* otherwise <label>.<hostname> */
	while ((ch = *dn++) != '\0') {
		if (!domainchar(ch))
			return (0);
		if (!escaped && periodchar(ch))
			break;
		if (escaped)
			escaped = 0;
		else if (bslashchar(ch))
			escaped = 1;
	}
	if (periodchar(ch))
		return (res_hnok(dn));
	return(0);
}

/*
 * This function is quite liberal, since RFC 1034's character sets are only
 * recommendations.
 */
int
res_dnok(dn)
	const char *dn;
{
	int ch;

	while ((ch = *dn++) != '\0')
		if (!domainchar(ch))
			return (0);
	return (1);
}

/*
 * Routines to insert/extract short/long's.
 */

u_int16_t
_getshort(msgp)
	register const u_char *msgp;
{
	register u_int16_t u;

	GETSHORT(u, msgp);
	return (u);
}

#ifdef NeXT
/*
 * nExt machines have some funky library conventions, which we must maintain.
 */
u_int16_t
res_getshort(msgp)
	register const u_char *msgp;
{
	return (_getshort(msgp));
}
#endif

u_int32_t
_getlong(msgp)
	register const u_char *msgp;
{
	register u_int32_t u;

	GETLONG(u, msgp);
	return (u);
}

void
#if defined(__STDC__) || defined(__cplusplus)
__putshort(register u_int16_t s, register u_char *msgp)	/* must match proto */
#else
__putshort(s, msgp)
	register u_int16_t s;
	register u_char *msgp;
#endif
{
	PUTSHORT(s, msgp);
}

void
__putlong(l, msgp)
	register u_int32_t l;
	register u_char *msgp;
{
	PUTLONG(l, msgp);
}

#ifdef ultrix
/* ultrix 4.0 had some icky packaging in its libc.a.  alias for it here.
 * there is more gunk of this kind over in res_debug.c.
 */
#undef putshort
void
#if defined(__STDC__) || defined(__cplusplus)
putshort(register u_short s, register u_char *msgp)
#else
putshort(s, msgp)
	register u_short s;
	register u_char *msgp;
#endif
{
	__putshort(s, msgp);
}
#undef putlong
void
putlong(l, msgp)
	register u_int32_t l;
	register u_char *msgp;
{
	__putlong(l, msgp);
}

#undef dn_skipname
dn_skipname(comp_dn, eom)
	const u_char *comp_dn, *eom;
{
	return (__dn_skipname(comp_dn, eom));
}
#endif /* Ultrix 4.0 hackery */