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1/* $OpenBSD: res_comp.c,v 1.8 1997/07/09 01:08:49 millert Exp $ */
2
3/*
4 * ++Copyright++ 1985, 1993
5 * -
6 * Copyright (c) 1985, 1993
7 * The Regents of the University of California. 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 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed by the University of
20 * California, Berkeley and its contributors.
21 * 4. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 * -
37 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
38 *
39 * Permission to use, copy, modify, and distribute this software for any
40 * purpose with or without fee is hereby granted, provided that the above
41 * copyright notice and this permission notice appear in all copies, and that
42 * the name of Digital Equipment Corporation not be used in advertising or
43 * publicity pertaining to distribution of the document or software without
44 * specific, written prior permission.
45 *
46 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
47 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
48 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
49 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
50 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
51 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
52 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
53 * SOFTWARE.
54 * -
55 * --Copyright--
56 */
57
58#if defined(LIBC_SCCS) && !defined(lint)
59#if 0
60static char sccsid[] = "@(#)res_comp.c 8.1 (Berkeley) 6/4/93";
61static char rcsid[] = "$From: res_comp.c,v 8.11 1996/12/02 09:17:22 vixie Exp $";
62#else
63static char rcsid[] = "$OpenBSD: res_comp.c,v 1.8 1997/07/09 01:08:49 millert Exp $";
64#endif
65#endif /* LIBC_SCCS and not lint */
66
67#include <sys/types.h>
68#include <sys/param.h>
69#include <netinet/in.h>
70#include <arpa/nameser.h>
71
72#include <stdio.h>
73#include <resolv.h>
74#include <ctype.h>
75
76#include <unistd.h>
77#include <string.h>
78
79static int dn_find __P((u_char *exp_dn, u_char *msg,
80 u_char **dnptrs, u_char **lastdnptr));
81
82/*
83 * Expand compressed domain name 'comp_dn' to full domain name.
84 * 'msg' is a pointer to the begining of the message,
85 * 'eomorig' points to the first location after the message,
86 * 'exp_dn' is a pointer to a buffer of size 'length' for the result.
87 * Return size of compressed name or -1 if there was an error.
88 */
89int
90dn_expand(msg, eomorig, comp_dn, exp_dn, length)
91 const u_char *msg, *eomorig, *comp_dn;
92 char *exp_dn;
93 int length;
94{
95 register const u_char *cp;
96 register char *dn;
97 register int n, c;
98 char *eom;
99 int len = -1, checked = 0;
100
101 dn = exp_dn;
102 cp = comp_dn;
103 if (length > MAXHOSTNAMELEN-1)
104 length = MAXHOSTNAMELEN-1;
105 eom = exp_dn + length;
106 /*
107 * fetch next label in domain name
108 */
109 while ((n = *cp++)) {
110 /*
111 * Check for indirection
112 */
113 switch (n & INDIR_MASK) {
114 case 0:
115 if (dn != exp_dn) {
116 if (dn >= eom)
117 return (-1);
118 *dn++ = '.';
119 }
120 if (dn+n >= eom)
121 return (-1);
122 checked += n + 1;
123 while (--n >= 0) {
124 if (((c = *cp++) == '.') || (c == '\\')) {
125 if (dn + n + 2 >= eom)
126 return (-1);
127 *dn++ = '\\';
128 }
129 *dn++ = c;
130 if (cp >= eomorig) /* out of range */
131 return (-1);
132 }
133 break;
134
135 case INDIR_MASK:
136 if (len < 0)
137 len = cp - comp_dn + 1;
138 cp = msg + (((n & 0x3f) << 8) | (*cp & 0xff));
139 if (cp < msg || cp >= eomorig) /* out of range */
140 return (-1);
141 checked += 2;
142 /*
143 * Check for loops in the compressed name;
144 * if we've looked at the whole message,
145 * there must be a loop.
146 */
147 if (checked >= eomorig - msg)
148 return (-1);
149 break;
150
151 default:
152 return (-1); /* flag error */
153 }
154 }
155 *dn = '\0';
156 if (len < 0)
157 len = cp - comp_dn;
158 return (len);
159}
160
161/*
162 * Compress domain name 'exp_dn' into 'comp_dn'.
163 * Return the size of the compressed name or -1.
164 * 'length' is the size of the array pointed to by 'comp_dn'.
165 * 'dnptrs' is a list of pointers to previous compressed names. dnptrs[0]
166 * is a pointer to the beginning of the message. The list ends with NULL.
167 * 'lastdnptr' is a pointer to the end of the arrary pointed to
168 * by 'dnptrs'. Side effect is to update the list of pointers for
169 * labels inserted into the message as we compress the name.
170 * If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
171 * is NULL, we don't update the list.
172 */
173int
174dn_comp(exp_dn, comp_dn, length, dnptrs, lastdnptr)
175 const char *exp_dn;
176 u_char *comp_dn, **dnptrs, **lastdnptr;
177 int length;
178{
179 register u_char *cp, *dn;
180 register int c, l;
181 u_char **cpp, **lpp, *sp, *eob;
182 u_char *msg;
183
184 dn = (u_char *)exp_dn;
185 cp = comp_dn;
186 eob = cp + length;
187 lpp = cpp = NULL;
188 if (dnptrs != NULL) {
189 if ((msg = *dnptrs++) != NULL) {
190 for (cpp = dnptrs; *cpp != NULL; cpp++)
191 ;
192 lpp = cpp; /* end of list to search */
193 }
194 } else
195 msg = NULL;
196 for (c = *dn++; c != '\0'; ) {
197 /* look to see if we can use pointers */
198 if (msg != NULL) {
199 if ((l = dn_find(dn-1, msg, dnptrs, lpp)) >= 0) {
200 if (cp+1 >= eob)
201 return (-1);
202 *cp++ = (l >> 8) | INDIR_MASK;
203 *cp++ = l % 256;
204 return (cp - comp_dn);
205 }
206 /* not found, save it */
207 if (lastdnptr != NULL && cpp < lastdnptr-1) {
208 *cpp++ = cp;
209 *cpp = NULL;
210 }
211 }
212 sp = cp++; /* save ptr to length byte */
213 do {
214 if (c == '.') {
215 c = *dn++;
216 break;
217 }
218 if (c == '\\') {
219 if ((c = *dn++) == '\0')
220 break;
221 }
222 if (cp >= eob) {
223 if (msg != NULL)
224 *lpp = NULL;
225 return (-1);
226 }
227 *cp++ = c;
228 } while ((c = *dn++) != '\0');
229 /* catch trailing '.'s but not '..' */
230 if ((l = cp - sp - 1) == 0 && c == '\0') {
231 cp--;
232 break;
233 }
234 if (l <= 0 || l > MAXLABEL) {
235 if (msg != NULL)
236 *lpp = NULL;
237 return (-1);
238 }
239 *sp = l;
240 }
241 if (cp >= eob) {
242 if (msg != NULL)
243 *lpp = NULL;
244 return (-1);
245 }
246 *cp++ = '\0';
247 return (cp - comp_dn);
248}
249
250/*
251 * Skip over a compressed domain name. Return the size or -1.
252 */
253int
254__dn_skipname(comp_dn, eom)
255 const u_char *comp_dn, *eom;
256{
257 register const u_char *cp;
258 register int n;
259
260 cp = comp_dn;
261 while (cp < eom && (n = *cp++)) {
262 /*
263 * check for indirection
264 */
265 switch (n & INDIR_MASK) {
266 case 0: /* normal case, n == len */
267 cp += n;
268 continue;
269 case INDIR_MASK: /* indirection */
270 cp++;
271 break;
272 default: /* illegal type */
273 return (-1);
274 }
275 break;
276 }
277 if (cp > eom)
278 return (-1);
279 return (cp - comp_dn);
280}
281
282static int
283mklower(ch)
284 register int ch;
285{
286 if (isascii(ch) && isupper(ch))
287 return (tolower(ch));
288 return (ch);
289}
290
291/*
292 * Search for expanded name from a list of previously compressed names.
293 * Return the offset from msg if found or -1.
294 * dnptrs is the pointer to the first name on the list,
295 * not the pointer to the start of the message.
296 */
297static int
298dn_find(exp_dn, msg, dnptrs, lastdnptr)
299 u_char *exp_dn, *msg;
300 u_char **dnptrs, **lastdnptr;
301{
302 register u_char *dn, *cp, **cpp;
303 register int n;
304 u_char *sp;
305
306 for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
307 dn = exp_dn;
308 sp = cp = *cpp;
309 while ((n = *cp++)) {
310 /*
311 * check for indirection
312 */
313 switch (n & INDIR_MASK) {
314 case 0: /* normal case, n == len */
315 while (--n >= 0) {
316 if (*dn == '.')
317 goto next;
318 if (*dn == '\\')
319 dn++;
320 if (mklower(*dn++) != mklower(*cp++))
321 goto next;
322 }
323 if ((n = *dn++) == '\0' && *cp == '\0')
324 return (sp - msg);
325 if (n == '.')
326 continue;
327 goto next;
328
329 case INDIR_MASK: /* indirection */
330 cp = msg + (((n & 0x3f) << 8) | *cp);
331 break;
332
333 default: /* illegal type */
334 return (-1);
335 }
336 }
337 if (*dn == '\0')
338 return (sp - msg);
339 next: ;
340 }
341 return (-1);
342}
343
344/*
345 * Verify that a domain name uses an acceptable character set.
346 */
347
348/*
349 * Note the conspicuous absence of ctype macros in these definitions. On
350 * non-ASCII hosts, we can't depend on string literals or ctype macros to
351 * tell us anything about network-format data. The rest of the BIND system
352 * is not careful about this, but for some reason, we're doing it right here.
353 */
354#define PERIOD 0x2e
355#define hyphenchar(c) ((c) == 0x2d)
356#define bslashchar(c) ((c) == 0x5c)
357#define periodchar(c) ((c) == PERIOD)
358#define asterchar(c) ((c) == 0x2a)
359#define alphachar(c) (((c) >= 0x41 && (c) <= 0x5a) \
360 || ((c) >= 0x61 && (c) <= 0x7a))
361#define digitchar(c) ((c) >= 0x30 && (c) <= 0x39)
362
363#define borderchar(c) (alphachar(c) || digitchar(c))
364#define middlechar(c) (borderchar(c) || hyphenchar(c))
365#define domainchar(c) ((c) > 0x20 && (c) < 0x7f)
366
367int
368res_hnok(dn)
369 const char *dn;
370{
371 int pch = PERIOD, ch = *dn++;
372
373 while (ch != '\0') {
374 int nch = *dn++;
375
376 if (periodchar(ch)) {
377 ;
378 } else if (periodchar(pch)) {
379 if (!borderchar(ch))
380 return (0);
381 } else if (periodchar(nch) || nch == '\0') {
382 if (!borderchar(ch))
383 return (0);
384 } else {
385 if (!middlechar(ch))
386 return (0);
387 }
388 pch = ch, ch = nch;
389 }
390 return (1);
391}
392
393/*
394 * hostname-like (A, MX, WKS) owners can have "*" as their first label
395 * but must otherwise be as a host name.
396 */
397int
398res_ownok(dn)
399 const char *dn;
400{
401 if (asterchar(dn[0])) {
402 if (periodchar(dn[1]))
403 return (res_hnok(dn+2));
404 if (dn[1] == '\0')
405 return (1);
406 }
407 return (res_hnok(dn));
408}
409
410/*
411 * SOA RNAMEs and RP RNAMEs can have any printable character in their first
412 * label, but the rest of the name has to look like a host name.
413 */
414int
415res_mailok(dn)
416 const char *dn;
417{
418 int ch, escaped = 0;
419
420 /* "." is a valid missing representation */
421 if (*dn == '\0')
422 return(1);
423
424 /* otherwise <label>.<hostname> */
425 while ((ch = *dn++) != '\0') {
426 if (!domainchar(ch))
427 return (0);
428 if (!escaped && periodchar(ch))
429 break;
430 if (escaped)
431 escaped = 0;
432 else if (bslashchar(ch))
433 escaped = 1;
434 }
435 if (periodchar(ch))
436 return (res_hnok(dn));
437 return(0);
438}
439
440/*
441 * This function is quite liberal, since RFC 1034's character sets are only
442 * recommendations.
443 */
444int
445res_dnok(dn)
446 const char *dn;
447{
448 int ch;
449
450 while ((ch = *dn++) != '\0')
451 if (!domainchar(ch))
452 return (0);
453 return (1);
454}
455
456/*
457 * Routines to insert/extract short/long's.
458 */
459
460u_int16_t
461_getshort(msgp)
462 register const u_char *msgp;
463{
464 register u_int16_t u;
465
466 GETSHORT(u, msgp);
467 return (u);
468}
469
470#ifdef NeXT
471/*
472 * nExt machines have some funky library conventions, which we must maintain.
473 */
474u_int16_t
475res_getshort(msgp)
476 register const u_char *msgp;
477{
478 return (_getshort(msgp));
479}
480#endif
481
482u_int32_t
483_getlong(msgp)
484 register const u_char *msgp;
485{
486 register u_int32_t u;
487
488 GETLONG(u, msgp);
489 return (u);
490}
491
492void
493#if defined(__STDC__) || defined(__cplusplus)
494__putshort(register u_int16_t s, register u_char *msgp) /* must match proto */
495#else
496__putshort(s, msgp)
497 register u_int16_t s;
498 register u_char *msgp;
499#endif
500{
501 PUTSHORT(s, msgp);
502}
503
504void
505__putlong(l, msgp)
506 register u_int32_t l;
507 register u_char *msgp;
508{
509 PUTLONG(l, msgp);
510}