xref: /illumos-gate/usr/src/lib/libresolv2/common/nameser/ns_name.c (revision 55fea89dcaa64928bed4327112404dcb3e07b79f)
1 /*
2  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3  * Copyright (c) 1996,1999 by Internet Software Consortium.
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
15  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include "port_before.h"
19 
20 #include <sys/types.h>
21 
22 #include <netinet/in.h>
23 #include <arpa/nameser.h>
24 
25 #include <errno.h>
26 #include <resolv.h>
27 #include <string.h>
28 #include <ctype.h>
29 #include <stdlib.h>
30 #include <limits.h>
31 
32 #include "port_after.h"
33 
34 #ifdef SPRINTF_CHAR
35 # define SPRINTF(x) strlen(sprintf/**/x)
36 #else
37 # define SPRINTF(x) ((size_t)sprintf x)
38 #endif
39 
40 #define NS_TYPE_ELT			0x40 /*%< EDNS0 extended label type */
41 #define DNS_LABELTYPE_BITSTRING		0x41
42 
43 /* Data. */
44 
45 static const char	digits[] = "0123456789";
46 
47 static const char digitvalue[256] = {
48 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,	/*16*/
49 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*32*/
50 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*48*/
51 	 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1, /*64*/
52 	-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*80*/
53 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*96*/
54 	-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*112*/
55 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*128*/
56 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
57 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
58 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
59 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
60 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
61 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
62 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
63 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*256*/
64 };
65 
66 /* Forward. */
67 
68 static int		special(int);
69 static int		printable(int);
70 static int		dn_find(const u_char *, const u_char *,
71 				const u_char * const *,
72 				const u_char * const *);
73 static int		encode_bitsring(const char **, const char *,
74 					unsigned char **, unsigned char **,
75 					unsigned const char *);
76 static int		labellen(const u_char *);
77 static int		decode_bitstring(const unsigned char **,
78 					 char *, const char *);
79 
80 /* Public. */
81 
82 /*%
83  *	Convert an encoded domain name to printable ascii as per RFC1035.
84 
85  * return:
86  *\li	Number of bytes written to buffer, or -1 (with errno set)
87  *
88  * notes:
89  *\li	The root is returned as "."
90  *\li	All other domains are returned in non absolute form
91  */
92 int
ns_name_ntop(const u_char * src,char * dst,size_t dstsiz)93 ns_name_ntop(const u_char *src, char *dst, size_t dstsiz)
94 {
95 	const u_char *cp;
96 	char *dn, *eom;
97 	u_char c;
98 	u_int n;
99 	int l;
100 
101 	cp = src;
102 	dn = dst;
103 	eom = dst + dstsiz;
104 
105 	while ((n = *cp++) != 0) {
106 		if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
107 			/* Some kind of compression pointer. */
108 			errno = EMSGSIZE;
109 			return (-1);
110 		}
111 		if (dn != dst) {
112 			if (dn >= eom) {
113 				errno = EMSGSIZE;
114 				return (-1);
115 			}
116 			*dn++ = '.';
117 		}
118 		if ((l = labellen(cp - 1)) < 0) {
119 			errno = EMSGSIZE; /*%< XXX */
120 			return (-1);
121 		}
122 		if (dn + l >= eom) {
123 			errno = EMSGSIZE;
124 			return (-1);
125 		}
126 		if ((n & NS_CMPRSFLGS) == NS_TYPE_ELT) {
127 			int m;
128 
129 			if (n != DNS_LABELTYPE_BITSTRING) {
130 				/* XXX: labellen should reject this case */
131 				errno = EINVAL;
132 				return (-1);
133 			}
134 			if ((m = decode_bitstring(&cp, dn, eom)) < 0)
135 			{
136 				errno = EMSGSIZE;
137 				return (-1);
138 			}
139 			dn += m;
140 			continue;
141 		}
142 		for ((void)NULL; l > 0; l--) {
143 			c = *cp++;
144 			if (special(c)) {
145 				if (dn + 1 >= eom) {
146 					errno = EMSGSIZE;
147 					return (-1);
148 				}
149 				*dn++ = '\\';
150 				*dn++ = (char)c;
151 			} else if (!printable(c)) {
152 				if (dn + 3 >= eom) {
153 					errno = EMSGSIZE;
154 					return (-1);
155 				}
156 				*dn++ = '\\';
157 				*dn++ = digits[c / 100];
158 				*dn++ = digits[(c % 100) / 10];
159 				*dn++ = digits[c % 10];
160 			} else {
161 				if (dn >= eom) {
162 					errno = EMSGSIZE;
163 					return (-1);
164 				}
165 				*dn++ = (char)c;
166 			}
167 		}
168 	}
169 	if (dn == dst) {
170 		if (dn >= eom) {
171 			errno = EMSGSIZE;
172 			return (-1);
173 		}
174 		*dn++ = '.';
175 	}
176 	if (dn >= eom) {
177 		errno = EMSGSIZE;
178 		return (-1);
179 	}
180 	*dn++ = '\0';
181 	return (dn - dst);
182 }
183 
184 /*%
185  *	Convert a ascii string into an encoded domain name as per RFC1035.
186  *
187  * return:
188  *
189  *\li	-1 if it fails
190  *\li	1 if string was fully qualified
191  *\li	0 is string was not fully qualified
192  *
193  * notes:
194  *\li	Enforces label and domain length limits.
195  */
196 int
ns_name_pton(const char * src,u_char * dst,size_t dstsiz)197 ns_name_pton(const char *src, u_char *dst, size_t dstsiz) {
198 	return (ns_name_pton2(src, dst, dstsiz, NULL));
199 }
200 
201 /*
202  * ns_name_pton2(src, dst, dstsiz, *dstlen)
203  *	Convert a ascii string into an encoded domain name as per RFC1035.
204  * return:
205  *	-1 if it fails
206  *	1 if string was fully qualified
207  *	0 is string was not fully qualified
208  * side effects:
209  *	fills in *dstlen (if non-NULL)
210  * notes:
211  *	Enforces label and domain length limits.
212  */
213 int
ns_name_pton2(const char * src,u_char * dst,size_t dstsiz,size_t * dstlen)214 ns_name_pton2(const char *src, u_char *dst, size_t dstsiz, size_t *dstlen) {
215 	u_char *label, *bp, *eom;
216 	int c, n, escaped, e = 0;
217 	char *cp;
218 
219 	escaped = 0;
220 	bp = dst;
221 	eom = dst + dstsiz;
222 	label = bp++;
223 
224 	while ((c = *src++) != 0) {
225 		if (escaped) {
226 			if (c == '[') { /*%< start a bit string label */
227 				if ((cp = strchr(src, ']')) == NULL) {
228 					errno = EINVAL; /*%< ??? */
229 					return (-1);
230 				}
231 				if ((e = encode_bitsring(&src, cp + 2,
232 							 &label, &bp, eom))
233 				    != 0) {
234 					errno = e;
235 					return (-1);
236 				}
237 				escaped = 0;
238 				label = bp++;
239 				if ((c = *src++) == 0)
240 					goto done;
241 				else if (c != '.') {
242 					errno = EINVAL;
243 					return	(-1);
244 				}
245 				continue;
246 			}
247 			else if ((cp = strchr(digits, c)) != NULL) {
248 				n = (cp - digits) * 100;
249 				if ((c = *src++) == 0 ||
250 				    (cp = strchr(digits, c)) == NULL) {
251 					errno = EMSGSIZE;
252 					return (-1);
253 				}
254 				n += (cp - digits) * 10;
255 				if ((c = *src++) == 0 ||
256 				    (cp = strchr(digits, c)) == NULL) {
257 					errno = EMSGSIZE;
258 					return (-1);
259 				}
260 				n += (cp - digits);
261 				if (n > 255) {
262 					errno = EMSGSIZE;
263 					return (-1);
264 				}
265 				c = n;
266 			}
267 			escaped = 0;
268 		} else if (c == '\\') {
269 			escaped = 1;
270 			continue;
271 		} else if (c == '.') {
272 			c = (bp - label - 1);
273 			if ((c & NS_CMPRSFLGS) != 0) {	/*%< Label too big. */
274 				errno = EMSGSIZE;
275 				return (-1);
276 			}
277 			if (label >= eom) {
278 				errno = EMSGSIZE;
279 				return (-1);
280 			}
281 			*label = c;
282 			/* Fully qualified ? */
283 			if (*src == '\0') {
284 				if (c != 0) {
285 					if (bp >= eom) {
286 						errno = EMSGSIZE;
287 						return (-1);
288 					}
289 					*bp++ = '\0';
290 				}
291 				if ((bp - dst) > MAXCDNAME) {
292 					errno = EMSGSIZE;
293 					return (-1);
294 				}
295 				if (dstlen != NULL)
296 					*dstlen = (bp - dst);
297 				return (1);
298 			}
299 			if (c == 0 || *src == '.') {
300 				errno = EMSGSIZE;
301 				return (-1);
302 			}
303 			label = bp++;
304 			continue;
305 		}
306 		if (bp >= eom) {
307 			errno = EMSGSIZE;
308 			return (-1);
309 		}
310 		*bp++ = (u_char)c;
311 	}
312 	c = (bp - label - 1);
313 	if ((c & NS_CMPRSFLGS) != 0) {		/*%< Label too big. */
314 		errno = EMSGSIZE;
315 		return (-1);
316 	}
317   done:
318 	if (label >= eom) {
319 		errno = EMSGSIZE;
320 		return (-1);
321 	}
322 	*label = c;
323 	if (c != 0) {
324 		if (bp >= eom) {
325 			errno = EMSGSIZE;
326 			return (-1);
327 		}
328 		*bp++ = 0;
329 	}
330 	if ((bp - dst) > MAXCDNAME) {	/*%< src too big */
331 		errno = EMSGSIZE;
332 		return (-1);
333 	}
334 	if (dstlen != NULL)
335 		*dstlen = (bp - dst);
336 	return (0);
337 }
338 
339 /*%
340  *	Convert a network strings labels into all lowercase.
341  *
342  * return:
343  *\li	Number of bytes written to buffer, or -1 (with errno set)
344  *
345  * notes:
346  *\li	Enforces label and domain length limits.
347  */
348 
349 int
ns_name_ntol(const u_char * src,u_char * dst,size_t dstsiz)350 ns_name_ntol(const u_char *src, u_char *dst, size_t dstsiz)
351 {
352 	const u_char *cp;
353 	u_char *dn, *eom;
354 	u_char c;
355 	u_int n;
356 	int l;
357 
358 	cp = src;
359 	dn = dst;
360 	eom = dst + dstsiz;
361 
362 	if (dn >= eom) {
363 		errno = EMSGSIZE;
364 		return (-1);
365 	}
366 	while ((n = *cp++) != 0) {
367 		if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
368 			/* Some kind of compression pointer. */
369 			errno = EMSGSIZE;
370 			return (-1);
371 		}
372 		*dn++ = n;
373 		if ((l = labellen(cp - 1)) < 0) {
374 			errno = EMSGSIZE;
375 			return (-1);
376 		}
377 		if (dn + l >= eom) {
378 			errno = EMSGSIZE;
379 			return (-1);
380 		}
381 		for ((void)NULL; l > 0; l--) {
382 			c = *cp++;
383 			if (isascii(c) && isupper(c))
384 				*dn++ = tolower(c);
385 			else
386 				*dn++ = c;
387 		}
388 	}
389 	*dn++ = '\0';
390 	return (dn - dst);
391 }
392 
393 /*%
394  *	Unpack a domain name from a message, source may be compressed.
395  *
396  * return:
397  *\li	-1 if it fails, or consumed octets if it succeeds.
398  */
399 int
ns_name_unpack(const u_char * msg,const u_char * eom,const u_char * src,u_char * dst,size_t dstsiz)400 ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
401 	       u_char *dst, size_t dstsiz)
402 {
403 	return (ns_name_unpack2(msg, eom, src, dst, dstsiz, NULL));
404 }
405 
406 /*
407  * ns_name_unpack2(msg, eom, src, dst, dstsiz, *dstlen)
408  *	Unpack a domain name from a message, source may be compressed.
409  * return:
410  *	-1 if it fails, or consumed octets if it succeeds.
411  * side effect:
412  *	fills in *dstlen (if non-NULL).
413  */
414 int
ns_name_unpack2(const u_char * msg,const u_char * eom,const u_char * src,u_char * dst,size_t dstsiz,size_t * dstlen)415 ns_name_unpack2(const u_char *msg, const u_char *eom, const u_char *src,
416 		u_char *dst, size_t dstsiz, size_t *dstlen)
417 {
418 	const u_char *srcp, *dstlim;
419 	u_char *dstp;
420 	int n, len, checked, l;
421 
422 	len = -1;
423 	checked = 0;
424 	dstp = dst;
425 	srcp = src;
426 	dstlim = dst + dstsiz;
427 	if (srcp < msg || srcp >= eom) {
428 		errno = EMSGSIZE;
429 		return (-1);
430 	}
431 	/* Fetch next label in domain name. */
432 	while ((n = *srcp++) != 0) {
433 		/* Check for indirection. */
434 		switch (n & NS_CMPRSFLGS) {
435 		case 0:
436 		case NS_TYPE_ELT:
437 			/* Limit checks. */
438 			if ((l = labellen(srcp - 1)) < 0) {
439 				errno = EMSGSIZE;
440 				return (-1);
441 			}
442 			if (dstp + l + 1 >= dstlim || srcp + l >= eom) {
443 				errno = EMSGSIZE;
444 				return (-1);
445 			}
446 			checked += l + 1;
447 			*dstp++ = n;
448 			memcpy(dstp, srcp, l);
449 			dstp += l;
450 			srcp += l;
451 			break;
452 
453 		case NS_CMPRSFLGS:
454 			if (srcp >= eom) {
455 				errno = EMSGSIZE;
456 				return (-1);
457 			}
458 			if (len < 0)
459 				len = srcp - src + 1;
460 			srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
461 			if (srcp < msg || srcp >= eom) {  /*%< Out of range. */
462 				errno = EMSGSIZE;
463 				return (-1);
464 			}
465 			checked += 2;
466 			/*
467 			 * Check for loops in the compressed name;
468 			 * if we've looked at the whole message,
469 			 * there must be a loop.
470 			 */
471 			if (checked >= eom - msg) {
472 				errno = EMSGSIZE;
473 				return (-1);
474 			}
475 			break;
476 
477 		default:
478 			errno = EMSGSIZE;
479 			return (-1);			/*%< flag error */
480 		}
481 	}
482 	*dstp++ = 0;
483 	if (dstlen != NULL)
484 		*dstlen = dstp - dst;
485 	if (len < 0)
486 		len = srcp - src;
487 	return (len);
488 }
489 
490 /*%
491  *	Pack domain name 'domain' into 'comp_dn'.
492  *
493  * return:
494  *\li	Size of the compressed name, or -1.
495  *
496  * notes:
497  *\li	'dnptrs' is an array of pointers to previous compressed names.
498  *\li	dnptrs[0] is a pointer to the beginning of the message. The array
499  *	ends with NULL.
500  *\li	'lastdnptr' is a pointer to the end of the array pointed to
501  *	by 'dnptrs'.
502  *
503  * Side effects:
504  *\li	The list of pointers in dnptrs is updated for labels inserted into
505  *	the message as we compress the name.  If 'dnptr' is NULL, we don't
506  *	try to compress names. If 'lastdnptr' is NULL, we don't update the
507  *	list.
508  */
509 int
ns_name_pack(const u_char * src,u_char * dst,int dstsiz,const u_char ** dnptrs,const u_char ** lastdnptr)510 ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
511 	     const u_char **dnptrs, const u_char **lastdnptr)
512 {
513 	u_char *dstp;
514 	const u_char **cpp, **lpp, *eob, *msg;
515 	const u_char *srcp;
516 	int n, l, first = 1;
517 
518 	srcp = src;
519 	dstp = dst;
520 	eob = dstp + dstsiz;
521 	lpp = cpp = NULL;
522 	if (dnptrs != NULL) {
523 		if ((msg = *dnptrs++) != NULL) {
524 			for (cpp = dnptrs; *cpp != NULL; cpp++)
525 				(void)NULL;
526 			lpp = cpp;	/*%< end of list to search */
527 		}
528 	} else
529 		msg = NULL;
530 
531 	/* make sure the domain we are about to add is legal */
532 	l = 0;
533 	do {
534 		int l0;
535 
536 		n = *srcp;
537 		if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
538 			errno = EMSGSIZE;
539 			return (-1);
540 		}
541 		if ((l0 = labellen(srcp)) < 0) {
542 			errno = EINVAL;
543 			return (-1);
544 		}
545 		l += l0 + 1;
546 		if (l > MAXCDNAME) {
547 			errno = EMSGSIZE;
548 			return (-1);
549 		}
550 		srcp += l0 + 1;
551 	} while (n != 0);
552 
553 	/* from here on we need to reset compression pointer array on error */
554 	srcp = src;
555 	do {
556 		/* Look to see if we can use pointers. */
557 		n = *srcp;
558 		if (n != 0 && msg != NULL) {
559 			l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
560 				    (const u_char * const *)lpp);
561 			if (l >= 0) {
562 				if (dstp + 1 >= eob) {
563 					goto cleanup;
564 				}
565 				*dstp++ = (l >> 8) | NS_CMPRSFLGS;
566 				*dstp++ = l % 256;
567 				return (dstp - dst);
568 			}
569 			/* Not found, save it. */
570 			if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
571 			    (dstp - msg) < 0x4000 && first) {
572 				*cpp++ = dstp;
573 				*cpp = NULL;
574 				first = 0;
575 			}
576 		}
577 		/* copy label to buffer */
578 		if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
579 			/* Should not happen. */
580 			goto cleanup;
581 		}
582 		n = labellen(srcp);
583 		if (dstp + 1 + n >= eob) {
584 			goto cleanup;
585 		}
586 		memcpy(dstp, srcp, n + 1);
587 		srcp += n + 1;
588 		dstp += n + 1;
589 	} while (n != 0);
590 
591 	if (dstp > eob) {
592 cleanup:
593 		if (msg != NULL)
594 			*lpp = NULL;
595 		errno = EMSGSIZE;
596 		return (-1);
597 	}
598 	return (dstp - dst);
599 }
600 
601 /*%
602  *	Expand compressed domain name to presentation format.
603  *
604  * return:
605  *\li	Number of bytes read out of `src', or -1 (with errno set).
606  *
607  * note:
608  *\li	Root domain returns as "." not "".
609  */
610 int
ns_name_uncompress(const u_char * msg,const u_char * eom,const u_char * src,char * dst,size_t dstsiz)611 ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
612 		   char *dst, size_t dstsiz)
613 {
614 	u_char tmp[NS_MAXCDNAME];
615 	int n;
616 
617 	if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
618 		return (-1);
619 	if (ns_name_ntop(tmp, dst, dstsiz) == -1)
620 		return (-1);
621 	return (n);
622 }
623 
624 /*%
625  *	Compress a domain name into wire format, using compression pointers.
626  *
627  * return:
628  *\li	Number of bytes consumed in `dst' or -1 (with errno set).
629  *
630  * notes:
631  *\li	'dnptrs' is an array of pointers to previous compressed names.
632  *\li	dnptrs[0] is a pointer to the beginning of the message.
633  *\li	The list ends with NULL.  'lastdnptr' is a pointer to the end of the
634  *	array pointed to by 'dnptrs'. Side effect is to update the list of
635  *	pointers for labels inserted into the message as we compress the name.
636  *\li	If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
637  *	is NULL, we don't update the list.
638  */
639 int
ns_name_compress(const char * src,u_char * dst,size_t dstsiz,const u_char ** dnptrs,const u_char ** lastdnptr)640 ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
641 		 const u_char **dnptrs, const u_char **lastdnptr)
642 {
643 	u_char tmp[NS_MAXCDNAME];
644 
645 	if (ns_name_pton(src, tmp, sizeof tmp) == -1)
646 		return (-1);
647 	return (ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
648 }
649 
650 /*%
651  * Reset dnptrs so that there are no active references to pointers at or
652  * after src.
653  */
654 void
ns_name_rollback(const u_char * src,const u_char ** dnptrs,const u_char ** lastdnptr)655 ns_name_rollback(const u_char *src, const u_char **dnptrs,
656 		 const u_char **lastdnptr)
657 {
658 	while (dnptrs < lastdnptr && *dnptrs != NULL) {
659 		if (*dnptrs >= src) {
660 			*dnptrs = NULL;
661 			break;
662 		}
663 		dnptrs++;
664 	}
665 }
666 
667 /*%
668  *	Advance *ptrptr to skip over the compressed name it points at.
669  *
670  * return:
671  *\li	0 on success, -1 (with errno set) on failure.
672  */
673 int
ns_name_skip(const u_char ** ptrptr,const u_char * eom)674 ns_name_skip(const u_char **ptrptr, const u_char *eom)
675 {
676 	const u_char *cp;
677 	u_int n;
678 	int l;
679 
680 	cp = *ptrptr;
681 	while (cp < eom && (n = *cp++) != 0) {
682 		/* Check for indirection. */
683 		switch (n & NS_CMPRSFLGS) {
684 		case 0:			/*%< normal case, n == len */
685 			cp += n;
686 			continue;
687 		case NS_TYPE_ELT: /*%< EDNS0 extended label */
688 			if ((l = labellen(cp - 1)) < 0) {
689 				errno = EMSGSIZE; /*%< XXX */
690 				return (-1);
691 			}
692 			cp += l;
693 			continue;
694 		case NS_CMPRSFLGS:	/*%< indirection */
695 			cp++;
696 			break;
697 		default:		/*%< illegal type */
698 			errno = EMSGSIZE;
699 			return (-1);
700 		}
701 		break;
702 	}
703 	if (cp > eom) {
704 		errno = EMSGSIZE;
705 		return (-1);
706 	}
707 	*ptrptr = cp;
708 	return (0);
709 }
710 
711 /* Find the number of octets an nname takes up, including the root label.
712  * (This is basically ns_name_skip() without compression-pointer support.)
713  * ((NOTE: can only return zero if passed-in namesiz argument is zero.))
714  */
715 ssize_t
ns_name_length(ns_nname_ct nname,size_t namesiz)716 ns_name_length(ns_nname_ct nname, size_t namesiz) {
717 	ns_nname_ct orig = nname;
718 	u_int n;
719 
720 	while (namesiz-- > 0 && (n = *nname++) != 0) {
721 		if ((n & NS_CMPRSFLGS) != 0) {
722 			errno = EISDIR;
723 			return (-1);
724 		}
725 		if (n > namesiz) {
726 			errno = EMSGSIZE;
727 			return (-1);
728 		}
729 		nname += n;
730 		namesiz -= n;
731 	}
732 	return (nname - orig);
733 }
734 
735 /* Compare two nname's for equality.  Return -1 on error (setting errno).
736  */
737 int
ns_name_eq(ns_nname_ct a,size_t as,ns_nname_ct b,size_t bs)738 ns_name_eq(ns_nname_ct a, size_t as, ns_nname_ct b, size_t bs) {
739 	ns_nname_ct ae = a + as, be = b + bs;
740 	int ac, bc;
741 
742 	while (ac = *a, bc = *b, ac != 0 && bc != 0) {
743 		if ((ac & NS_CMPRSFLGS) != 0 || (bc & NS_CMPRSFLGS) != 0) {
744 			errno = EISDIR;
745 			return (-1);
746 		}
747 		if (a + ac >= ae || b + bc >= be) {
748 			errno = EMSGSIZE;
749 			return (-1);
750 		}
751 		if (ac != bc || strncasecmp((const char *) ++a,
752 					    (const char *) ++b, ac) != 0)
753 			return (0);
754 		a += ac, b += bc;
755 	}
756 	return (ac == 0 && bc == 0);
757 }
758 
759 /* Is domain "A" owned by (at or below) domain "B"?
760  */
761 int
ns_name_owned(ns_namemap_ct a,int an,ns_namemap_ct b,int bn)762 ns_name_owned(ns_namemap_ct a, int an, ns_namemap_ct b, int bn) {
763 	/* If A is shorter, it cannot be owned by B. */
764 	if (an < bn)
765 		return (0);
766 
767 	/* If they are unequal before the length of the shorter, A cannot... */
768 	while (bn > 0) {
769 		if (a->len != b->len ||
770 		    strncasecmp((const char *) a->base,
771 				(const char *) b->base, a->len) != 0)
772 			return (0);
773 		a++, an--;
774 		b++, bn--;
775 	}
776 
777 	/* A might be longer or not, but either way, B owns it. */
778 	return (1);
779 }
780 
781 /* Build an array of <base,len> tuples from an nname, top-down order.
782  * Return the number of tuples (labels) thus discovered.
783  */
784 int
ns_name_map(ns_nname_ct nname,size_t namelen,ns_namemap_t map,int mapsize)785 ns_name_map(ns_nname_ct nname, size_t namelen, ns_namemap_t map, int mapsize) {
786 	u_int n;
787 	int l;
788 
789 	n = *nname++;
790 	namelen--;
791 
792 	/* Root zone? */
793 	if (n == 0) {
794 		/* Extra data follows name? */
795 		if (namelen > 0) {
796 			errno = EMSGSIZE;
797 			return (-1);
798 		}
799 		return (0);
800 	}
801 
802 	/* Compression pointer? */
803 	if ((n & NS_CMPRSFLGS) != 0) {
804 		errno = EISDIR;
805 		return (-1);
806 	}
807 
808 	/* Label too long? */
809 	if (n > namelen) {
810 		errno = EMSGSIZE;
811 		return (-1);
812 	}
813 
814 	/* Recurse to get rest of name done first. */
815 	l = ns_name_map(nname + n, namelen - n, map, mapsize);
816 	if (l < 0)
817 		return (-1);
818 
819 	/* Too many labels? */
820 	if (l >= mapsize) {
821 		errno = ENAMETOOLONG;
822 		return (-1);
823 	}
824 
825 	/* We're on our way back up-stack, store current map data. */
826 	map[l].base = nname;
827 	map[l].len = n;
828 	return (l + 1);
829 }
830 
831 /* Count the labels in a domain name.  Root counts, so COM. has two.  This
832  * is to make the result comparable to the result of ns_name_map().
833  */
834 int
ns_name_labels(ns_nname_ct nname,size_t namesiz)835 ns_name_labels(ns_nname_ct nname, size_t namesiz) {
836 	int ret = 0;
837 	u_int n;
838 
839 	while (namesiz-- > 0 && (n = *nname++) != 0) {
840 		if ((n & NS_CMPRSFLGS) != 0) {
841 			errno = EISDIR;
842 			return (-1);
843 		}
844 		if (n > namesiz) {
845 			errno = EMSGSIZE;
846 			return (-1);
847 		}
848 		nname += n;
849 		namesiz -= n;
850 		ret++;
851 	}
852 	return (ret + 1);
853 }
854 
855 /* Private. */
856 
857 /*%
858  *	Thinking in noninternationalized USASCII (per the DNS spec),
859  *	is this characted special ("in need of quoting") ?
860  *
861  * return:
862  *\li	boolean.
863  */
864 static int
special(int ch)865 special(int ch) {
866 	switch (ch) {
867 	case 0x22: /*%< '"' */
868 	case 0x2E: /*%< '.' */
869 	case 0x3B: /*%< ';' */
870 	case 0x5C: /*%< '\\' */
871 	case 0x28: /*%< '(' */
872 	case 0x29: /*%< ')' */
873 	/* Special modifiers in zone files. */
874 	case 0x40: /*%< '@' */
875 	case 0x24: /*%< '$' */
876 		return (1);
877 	default:
878 		return (0);
879 	}
880 }
881 
882 /*%
883  *	Thinking in noninternationalized USASCII (per the DNS spec),
884  *	is this character visible and not a space when printed ?
885  *
886  * return:
887  *\li	boolean.
888  */
889 static int
printable(int ch)890 printable(int ch) {
891 	return (ch > 0x20 && ch < 0x7f);
892 }
893 
894 /*%
895  *	Thinking in noninternationalized USASCII (per the DNS spec),
896  *	convert this character to lower case if it's upper case.
897  */
898 static int
mklower(int ch)899 mklower(int ch) {
900 	if (ch >= 0x41 && ch <= 0x5A)
901 		return (ch + 0x20);
902 	return (ch);
903 }
904 
905 /*%
906  *	Search for the counted-label name in an array of compressed names.
907  *
908  * return:
909  *\li	offset from msg if found, or -1.
910  *
911  * notes:
912  *\li	dnptrs is the pointer to the first name on the list,
913  *\li	not the pointer to the start of the message.
914  */
915 static int
dn_find(const u_char * domain,const u_char * msg,const u_char * const * dnptrs,const u_char * const * lastdnptr)916 dn_find(const u_char *domain, const u_char *msg,
917 	const u_char * const *dnptrs,
918 	const u_char * const *lastdnptr)
919 {
920 	const u_char *dn, *cp, *sp;
921 	const u_char * const *cpp;
922 	u_int n;
923 
924 	for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
925 		sp = *cpp;
926 		/*
927 		 * terminate search on:
928 		 * root label
929 		 * compression pointer
930 		 * unusable offset
931 		 */
932 		while (*sp != 0 && (*sp & NS_CMPRSFLGS) == 0 &&
933 		       (sp - msg) < 0x4000) {
934 			dn = domain;
935 			cp = sp;
936 			while ((n = *cp++) != 0) {
937 				/*
938 				 * check for indirection
939 				 */
940 				switch (n & NS_CMPRSFLGS) {
941 				case 0:		/*%< normal case, n == len */
942 					n = labellen(cp - 1); /*%< XXX */
943 					if (n != *dn++)
944 						goto next;
945 
946 					for ((void)NULL; n > 0; n--)
947 						if (mklower(*dn++) !=
948 						    mklower(*cp++))
949 							goto next;
950 					/* Is next root for both ? */
951 					if (*dn == '\0' && *cp == '\0')
952 						return (sp - msg);
953 					if (*dn)
954 						continue;
955 					goto next;
956 				case NS_CMPRSFLGS:	/*%< indirection */
957 					cp = msg + (((n & 0x3f) << 8) | *cp);
958 					break;
959 
960 				default:	/*%< illegal type */
961 					errno = EMSGSIZE;
962 					return (-1);
963 				}
964 			}
965  next: ;
966 			sp += *sp + 1;
967 		}
968 	}
969 	errno = ENOENT;
970 	return (-1);
971 }
972 
973 static int
decode_bitstring(const unsigned char ** cpp,char * dn,const char * eom)974 decode_bitstring(const unsigned char **cpp, char *dn, const char *eom)
975 {
976 	const unsigned char *cp = *cpp;
977 	char *beg = dn, tc;
978 	int b, blen, plen, i;
979 
980 	if ((blen = (*cp & 0xff)) == 0)
981 		blen = 256;
982 	plen = (blen + 3) / 4;
983 	plen += sizeof("\\[x/]") + (blen > 99 ? 3 : (blen > 9) ? 2 : 1);
984 	if (dn + plen >= eom)
985 		return (-1);
986 
987 	cp++;
988 	i = SPRINTF((dn, "\\[x"));
989 	if (i < 0)
990 		return (-1);
991 	dn += i;
992 	for (b = blen; b > 7; b -= 8, cp++) {
993 		i = SPRINTF((dn, "%02x", *cp & 0xff));
994 		if (i < 0)
995 			return (-1);
996 		dn += i;
997 	}
998 	if (b > 4) {
999 		tc = *cp++;
1000 		i = SPRINTF((dn, "%02x", tc & (0xff << (8 - b))));
1001 		if (i < 0)
1002 			return (-1);
1003 		dn += i;
1004 	} else if (b > 0) {
1005 		tc = *cp++;
1006 		i = SPRINTF((dn, "%1x",
1007 			       ((tc >> 4) & 0x0f) & (0x0f << (4 - b))));
1008 		if (i < 0)
1009 			return (-1);
1010 		dn += i;
1011 	}
1012 	i = SPRINTF((dn, "/%d]", blen));
1013 	if (i < 0)
1014 		return (-1);
1015 	dn += i;
1016 
1017 	*cpp = cp;
1018 	return (dn - beg);
1019 }
1020 
1021 static int
encode_bitsring(const char ** bp,const char * end,unsigned char ** labelp,unsigned char ** dst,unsigned const char * eom)1022 encode_bitsring(const char **bp, const char *end, unsigned char **labelp,
1023 		unsigned char ** dst, unsigned const char *eom)
1024 {
1025 	int afterslash = 0;
1026 	const char *cp = *bp;
1027 	unsigned char *tp;
1028 	char c;
1029 	const char *beg_blen;
1030 	char *end_blen = NULL;
1031 	int value = 0, count = 0, tbcount = 0, blen = 0;
1032 
1033 	beg_blen = end_blen = NULL;
1034 
1035 	/* a bitstring must contain at least 2 characters */
1036 	if (end - cp < 2)
1037 		return (EINVAL);
1038 
1039 	/* XXX: currently, only hex strings are supported */
1040 	if (*cp++ != 'x')
1041 		return (EINVAL);
1042 	if (!isxdigit((*cp) & 0xff)) /*%< reject '\[x/BLEN]' */
1043 		return (EINVAL);
1044 
1045 	for (tp = *dst + 1; cp < end && tp < eom; cp++) {
1046 		switch((c = *cp)) {
1047 		case ']':	/*%< end of the bitstring */
1048 			if (afterslash) {
1049 				if (beg_blen == NULL)
1050 					return (EINVAL);
1051 				blen = (int)strtol(beg_blen, &end_blen, 10);
1052 				if (*end_blen != ']')
1053 					return (EINVAL);
1054 			}
1055 			if (count)
1056 				*tp++ = ((value << 4) & 0xff);
1057 			cp++;	/*%< skip ']' */
1058 			goto done;
1059 		case '/':
1060 			afterslash = 1;
1061 			break;
1062 		default:
1063 			if (afterslash) {
1064 				if (!isdigit(c&0xff))
1065 					return (EINVAL);
1066 				if (beg_blen == NULL) {
1067 
1068 					if (c == '0') {
1069 						/* blen never begings with 0 */
1070 						return (EINVAL);
1071 					}
1072 					beg_blen = cp;
1073 				}
1074 			} else {
1075 				if (!isxdigit(c&0xff))
1076 					return (EINVAL);
1077 				value <<= 4;
1078 				value += digitvalue[(int)c];
1079 				count += 4;
1080 				tbcount += 4;
1081 				if (tbcount > 256)
1082 					return (EINVAL);
1083 				if (count == 8) {
1084 					*tp++ = value;
1085 					count = 0;
1086 				}
1087 			}
1088 			break;
1089 		}
1090 	}
1091   done:
1092 	if (cp >= end || tp >= eom)
1093 		return (EMSGSIZE);
1094 
1095 	/*
1096 	 * bit length validation:
1097 	 * If a <length> is present, the number of digits in the <bit-data>
1098 	 * MUST be just sufficient to contain the number of bits specified
1099 	 * by the <length>. If there are insignificant bits in a final
1100 	 * hexadecimal or octal digit, they MUST be zero.
1101 	 * RFC2673, Section 3.2.
1102 	 */
1103 	if (blen > 0) {
1104 		int traillen;
1105 
1106 		if (((blen + 3) & ~3) != tbcount)
1107 			return (EINVAL);
1108 		traillen = tbcount - blen; /*%< between 0 and 3 */
1109 		if (((value << (8 - traillen)) & 0xff) != 0)
1110 			return (EINVAL);
1111 	}
1112 	else
1113 		blen = tbcount;
1114 	if (blen == 256)
1115 		blen = 0;
1116 
1117 	/* encode the type and the significant bit fields */
1118 	**labelp = DNS_LABELTYPE_BITSTRING;
1119 	**dst = blen;
1120 
1121 	*bp = cp;
1122 	*dst = tp;
1123 
1124 	return (0);
1125 }
1126 
1127 static int
labellen(const u_char * lp)1128 labellen(const u_char *lp)
1129 {
1130 	int bitlen;
1131 	u_char l = *lp;
1132 
1133 	if ((l & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
1134 		/* should be avoided by the caller */
1135 		return (-1);
1136 	}
1137 
1138 	if ((l & NS_CMPRSFLGS) == NS_TYPE_ELT) {
1139 		if (l == DNS_LABELTYPE_BITSTRING) {
1140 			if ((bitlen = *(lp + 1)) == 0)
1141 				bitlen = 256;
1142 			return ((bitlen + 7 ) / 8 + 1);
1143 		}
1144 		return (-1);	/*%< unknwon ELT */
1145 	}
1146 	return (l);
1147 }
1148 
1149 /*! \file */
1150