1 /* $NetBSD: rdataslab.c,v 1.1 2024/02/18 20:57:33 christos Exp $ */
2
3 /*
4 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
5 *
6 * SPDX-License-Identifier: MPL-2.0
7 *
8 * This Source Code Form is subject to the terms of the Mozilla Public
9 * License, v. 2.0. If a copy of the MPL was not distributed with this
10 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
11 *
12 * See the COPYRIGHT file distributed with this work for additional
13 * information regarding copyright ownership.
14 */
15
16 /*! \file */
17
18 #include <stdbool.h>
19 #include <stdlib.h>
20
21 #include <isc/mem.h>
22 #include <isc/region.h>
23 #include <isc/string.h> /* Required for HP/UX (and others?) */
24 #include <isc/util.h>
25
26 #include <dns/rdata.h>
27 #include <dns/rdataset.h>
28 #include <dns/rdataslab.h>
29 #include <dns/result.h>
30
31 /*
32 * The rdataslab structure allows iteration to occur in both load order
33 * and DNSSEC order. The structure is as follows:
34 *
35 * header (reservelen bytes)
36 * record count (2 bytes)
37 * offset table (4 x record count bytes in load order)
38 * data records
39 * data length (2 bytes)
40 * order (2 bytes)
41 * meta data (1 byte for RRSIG's)
42 * data (data length bytes)
43 *
44 * If DNS_RDATASET_FIXED is defined to be zero (0) the format of a
45 * rdataslab is as follows:
46 *
47 * header (reservelen bytes)
48 * record count (2 bytes)
49 * data records
50 * data length (2 bytes)
51 * meta data (1 byte for RRSIG's)
52 * data (data length bytes)
53 *
54 * Offsets are from the end of the header.
55 *
56 * Load order traversal is performed by walking the offset table to find
57 * the start of the record (DNS_RDATASET_FIXED = 1).
58 *
59 * DNSSEC order traversal is performed by walking the data records.
60 *
61 * The order is stored with record to allow for efficient reconstruction
62 * of the offset table following a merge or subtraction.
63 *
64 * The iterator methods in rbtdb support both load order and DNSSEC order
65 * iteration.
66 *
67 * WARNING:
68 * rbtdb.c directly interacts with the slab's raw structures. If the
69 * structure changes then rbtdb.c also needs to be updated to reflect
70 * the changes. See the areas tagged with "RDATASLAB".
71 */
72
73 struct xrdata {
74 dns_rdata_t rdata;
75 unsigned int order;
76 };
77
78 /*% Note: the "const void *" are just to make qsort happy. */
79 static int
compare_rdata(const void * p1,const void * p2)80 compare_rdata(const void *p1, const void *p2) {
81 const struct xrdata *x1 = p1;
82 const struct xrdata *x2 = p2;
83 return (dns_rdata_compare(&x1->rdata, &x2->rdata));
84 }
85
86 #if DNS_RDATASET_FIXED
87 static void
fillin_offsets(unsigned char * offsetbase,unsigned int * offsettable,unsigned length)88 fillin_offsets(unsigned char *offsetbase, unsigned int *offsettable,
89 unsigned length) {
90 unsigned int i, j;
91 unsigned char *raw;
92
93 for (i = 0, j = 0; i < length; i++) {
94 if (offsettable[i] == 0) {
95 continue;
96 }
97
98 /*
99 * Fill in offset table.
100 */
101 raw = &offsetbase[j * 4 + 2];
102 *raw++ = (offsettable[i] & 0xff000000) >> 24;
103 *raw++ = (offsettable[i] & 0xff0000) >> 16;
104 *raw++ = (offsettable[i] & 0xff00) >> 8;
105 *raw = offsettable[i] & 0xff;
106
107 /*
108 * Fill in table index.
109 */
110 raw = offsetbase + offsettable[i] + 2;
111 *raw++ = (j & 0xff00) >> 8;
112 *raw = j++ & 0xff;
113 }
114 }
115 #endif /* if DNS_RDATASET_FIXED */
116
117 isc_result_t
dns_rdataslab_fromrdataset(dns_rdataset_t * rdataset,isc_mem_t * mctx,isc_region_t * region,unsigned int reservelen)118 dns_rdataslab_fromrdataset(dns_rdataset_t *rdataset, isc_mem_t *mctx,
119 isc_region_t *region, unsigned int reservelen) {
120 /*
121 * Use &removed as a sentinel pointer for duplicate
122 * rdata as rdata.data == NULL is valid.
123 */
124 static unsigned char removed;
125 struct xrdata *x;
126 unsigned char *rawbuf;
127 #if DNS_RDATASET_FIXED
128 unsigned char *offsetbase;
129 #endif /* if DNS_RDATASET_FIXED */
130 unsigned int buflen;
131 isc_result_t result;
132 unsigned int nitems;
133 unsigned int nalloc;
134 unsigned int i;
135 #if DNS_RDATASET_FIXED
136 unsigned int *offsettable;
137 #endif /* if DNS_RDATASET_FIXED */
138 unsigned int length;
139
140 buflen = reservelen + 2;
141
142 nitems = dns_rdataset_count(rdataset);
143
144 /*
145 * If there are no rdata then we can just need to allocate a header
146 * with zero a record count.
147 */
148 if (nitems == 0) {
149 if (rdataset->type != 0) {
150 return (ISC_R_FAILURE);
151 }
152 rawbuf = isc_mem_get(mctx, buflen);
153 region->base = rawbuf;
154 region->length = buflen;
155 rawbuf += reservelen;
156 *rawbuf++ = 0;
157 *rawbuf = 0;
158 return (ISC_R_SUCCESS);
159 }
160
161 if (nitems > 0xffff) {
162 return (ISC_R_NOSPACE);
163 }
164
165 /*
166 * Remember the original number of items.
167 */
168 nalloc = nitems;
169 x = isc_mem_get(mctx, nalloc * sizeof(struct xrdata));
170
171 /*
172 * Save all of the rdata members into an array.
173 */
174 result = dns_rdataset_first(rdataset);
175 if (result != ISC_R_SUCCESS && result != ISC_R_NOMORE) {
176 goto free_rdatas;
177 }
178 for (i = 0; i < nalloc && result == ISC_R_SUCCESS; i++) {
179 INSIST(result == ISC_R_SUCCESS);
180 dns_rdata_init(&x[i].rdata);
181 dns_rdataset_current(rdataset, &x[i].rdata);
182 INSIST(x[i].rdata.data != &removed);
183 #if DNS_RDATASET_FIXED
184 x[i].order = i;
185 #endif /* if DNS_RDATASET_FIXED */
186 result = dns_rdataset_next(rdataset);
187 }
188 if (i != nalloc || result != ISC_R_NOMORE) {
189 /*
190 * Somehow we iterated over fewer rdatas than
191 * dns_rdataset_count() said there were or there
192 * were more items than dns_rdataset_count said
193 * there were.
194 */
195 result = ISC_R_FAILURE;
196 goto free_rdatas;
197 }
198
199 /*
200 * Put into DNSSEC order.
201 */
202 if (nalloc > 1U) {
203 qsort(x, nalloc, sizeof(struct xrdata), compare_rdata);
204 }
205
206 /*
207 * Remove duplicates and compute the total storage required.
208 *
209 * If an rdata is not a duplicate, accumulate the storage size
210 * required for the rdata. We do not store the class, type, etc,
211 * just the rdata, so our overhead is 2 bytes for the number of
212 * records, and 8 for each rdata, (length(2), offset(4) and order(2))
213 * and then the rdata itself.
214 */
215 for (i = 1; i < nalloc; i++) {
216 if (compare_rdata(&x[i - 1].rdata, &x[i].rdata) == 0) {
217 x[i - 1].rdata.data = &removed;
218 #if DNS_RDATASET_FIXED
219 /*
220 * Preserve the least order so A, B, A -> A, B
221 * after duplicate removal.
222 */
223 if (x[i - 1].order < x[i].order) {
224 x[i].order = x[i - 1].order;
225 }
226 #endif /* if DNS_RDATASET_FIXED */
227 nitems--;
228 } else {
229 #if DNS_RDATASET_FIXED
230 buflen += (8 + x[i - 1].rdata.length);
231 #else /* if DNS_RDATASET_FIXED */
232 buflen += (2 + x[i - 1].rdata.length);
233 #endif /* if DNS_RDATASET_FIXED */
234 /*
235 * Provide space to store the per RR meta data.
236 */
237 if (rdataset->type == dns_rdatatype_rrsig) {
238 buflen++;
239 }
240 }
241 }
242
243 /*
244 * Don't forget the last item!
245 */
246 #if DNS_RDATASET_FIXED
247 buflen += (8 + x[i - 1].rdata.length);
248 #else /* if DNS_RDATASET_FIXED */
249 buflen += (2 + x[i - 1].rdata.length);
250 #endif /* if DNS_RDATASET_FIXED */
251 /*
252 * Provide space to store the per RR meta data.
253 */
254 if (rdataset->type == dns_rdatatype_rrsig) {
255 buflen++;
256 }
257
258 /*
259 * Ensure that singleton types are actually singletons.
260 */
261 if (nitems > 1 && dns_rdatatype_issingleton(rdataset->type)) {
262 /*
263 * We have a singleton type, but there's more than one
264 * RR in the rdataset.
265 */
266 result = DNS_R_SINGLETON;
267 goto free_rdatas;
268 }
269
270 /*
271 * Allocate the memory, set up a buffer, start copying in
272 * data.
273 */
274 rawbuf = isc_mem_get(mctx, buflen);
275
276 #if DNS_RDATASET_FIXED
277 /* Allocate temporary offset table. */
278 offsettable = isc_mem_get(mctx, nalloc * sizeof(unsigned int));
279 memset(offsettable, 0, nalloc * sizeof(unsigned int));
280 #endif /* if DNS_RDATASET_FIXED */
281
282 region->base = rawbuf;
283 region->length = buflen;
284
285 memset(rawbuf, 0, buflen);
286 rawbuf += reservelen;
287
288 #if DNS_RDATASET_FIXED
289 offsetbase = rawbuf;
290 #endif /* if DNS_RDATASET_FIXED */
291
292 *rawbuf++ = (nitems & 0xff00) >> 8;
293 *rawbuf++ = (nitems & 0x00ff);
294
295 #if DNS_RDATASET_FIXED
296 /* Skip load order table. Filled in later. */
297 rawbuf += nitems * 4;
298 #endif /* if DNS_RDATASET_FIXED */
299
300 for (i = 0; i < nalloc; i++) {
301 if (x[i].rdata.data == &removed) {
302 continue;
303 }
304 #if DNS_RDATASET_FIXED
305 offsettable[x[i].order] = rawbuf - offsetbase;
306 #endif /* if DNS_RDATASET_FIXED */
307 length = x[i].rdata.length;
308 if (rdataset->type == dns_rdatatype_rrsig) {
309 length++;
310 }
311 INSIST(length <= 0xffff);
312 *rawbuf++ = (length & 0xff00) >> 8;
313 *rawbuf++ = (length & 0x00ff);
314 #if DNS_RDATASET_FIXED
315 rawbuf += 2; /* filled in later */
316 #endif /* if DNS_RDATASET_FIXED */
317 /*
318 * Store the per RR meta data.
319 */
320 if (rdataset->type == dns_rdatatype_rrsig) {
321 *rawbuf++ = (x[i].rdata.flags & DNS_RDATA_OFFLINE)
322 ? DNS_RDATASLAB_OFFLINE
323 : 0;
324 }
325 memmove(rawbuf, x[i].rdata.data, x[i].rdata.length);
326 rawbuf += x[i].rdata.length;
327 }
328
329 #if DNS_RDATASET_FIXED
330 fillin_offsets(offsetbase, offsettable, nalloc);
331 isc_mem_put(mctx, offsettable, nalloc * sizeof(unsigned int));
332 #endif /* if DNS_RDATASET_FIXED */
333
334 result = ISC_R_SUCCESS;
335
336 free_rdatas:
337 isc_mem_put(mctx, x, nalloc * sizeof(struct xrdata));
338 return (result);
339 }
340
341 unsigned int
dns_rdataslab_size(unsigned char * slab,unsigned int reservelen)342 dns_rdataslab_size(unsigned char *slab, unsigned int reservelen) {
343 unsigned int count, length;
344 unsigned char *current;
345
346 REQUIRE(slab != NULL);
347
348 current = slab + reservelen;
349 count = *current++ * 256;
350 count += *current++;
351 #if DNS_RDATASET_FIXED
352 current += (4 * count);
353 #endif /* if DNS_RDATASET_FIXED */
354 while (count > 0) {
355 count--;
356 length = *current++ * 256;
357 length += *current++;
358 #if DNS_RDATASET_FIXED
359 current += length + 2;
360 #else /* if DNS_RDATASET_FIXED */
361 current += length;
362 #endif /* if DNS_RDATASET_FIXED */
363 }
364
365 return ((unsigned int)(current - slab));
366 }
367
368 unsigned int
dns_rdataslab_rdatasize(unsigned char * slab,unsigned int reservelen)369 dns_rdataslab_rdatasize(unsigned char *slab, unsigned int reservelen) {
370 unsigned int count, length, rdatalen = 0;
371 unsigned char *current;
372
373 REQUIRE(slab != NULL);
374
375 current = slab + reservelen;
376 count = *current++ * 256;
377 count += *current++;
378 #if DNS_RDATASET_FIXED
379 current += (4 * count);
380 #endif /* if DNS_RDATASET_FIXED */
381 while (count > 0) {
382 count--;
383 length = *current++ * 256;
384 length += *current++;
385 rdatalen += length;
386 #if DNS_RDATASET_FIXED
387 current += length + 2;
388 #else /* if DNS_RDATASET_FIXED */
389 current += length;
390 #endif /* if DNS_RDATASET_FIXED */
391 }
392
393 return (rdatalen);
394 }
395
396 unsigned int
dns_rdataslab_count(unsigned char * slab,unsigned int reservelen)397 dns_rdataslab_count(unsigned char *slab, unsigned int reservelen) {
398 unsigned int count;
399 unsigned char *current;
400
401 REQUIRE(slab != NULL);
402
403 current = slab + reservelen;
404 count = *current++ * 256;
405 count += *current++;
406 return (count);
407 }
408
409 /*
410 * Make the dns_rdata_t 'rdata' refer to the slab item
411 * beginning at '*current', which is part of a slab of type
412 * 'type' and class 'rdclass', and advance '*current' to
413 * point to the next item in the slab.
414 */
415 static void
rdata_from_slab(unsigned char ** current,dns_rdataclass_t rdclass,dns_rdatatype_t type,dns_rdata_t * rdata)416 rdata_from_slab(unsigned char **current, dns_rdataclass_t rdclass,
417 dns_rdatatype_t type, dns_rdata_t *rdata) {
418 unsigned char *tcurrent = *current;
419 isc_region_t region;
420 unsigned int length;
421 bool offline = false;
422
423 length = *tcurrent++ * 256;
424 length += *tcurrent++;
425
426 if (type == dns_rdatatype_rrsig) {
427 if ((*tcurrent & DNS_RDATASLAB_OFFLINE) != 0) {
428 offline = true;
429 }
430 length--;
431 tcurrent++;
432 }
433 region.length = length;
434 #if DNS_RDATASET_FIXED
435 tcurrent += 2;
436 #endif /* if DNS_RDATASET_FIXED */
437 region.base = tcurrent;
438 tcurrent += region.length;
439 dns_rdata_fromregion(rdata, rdclass, type, ®ion);
440 if (offline) {
441 rdata->flags |= DNS_RDATA_OFFLINE;
442 }
443 *current = tcurrent;
444 }
445
446 /*
447 * Return true iff 'slab' (slab data of type 'type' and class 'rdclass')
448 * contains an rdata identical to 'rdata'. This does case insensitive
449 * comparisons per DNSSEC.
450 */
451 static bool
rdata_in_slab(unsigned char * slab,unsigned int reservelen,dns_rdataclass_t rdclass,dns_rdatatype_t type,dns_rdata_t * rdata)452 rdata_in_slab(unsigned char *slab, unsigned int reservelen,
453 dns_rdataclass_t rdclass, dns_rdatatype_t type,
454 dns_rdata_t *rdata) {
455 unsigned int count, i;
456 unsigned char *current;
457 dns_rdata_t trdata = DNS_RDATA_INIT;
458 int n;
459
460 current = slab + reservelen;
461 count = *current++ * 256;
462 count += *current++;
463
464 #if DNS_RDATASET_FIXED
465 current += (4 * count);
466 #endif /* if DNS_RDATASET_FIXED */
467
468 for (i = 0; i < count; i++) {
469 rdata_from_slab(¤t, rdclass, type, &trdata);
470
471 n = dns_rdata_compare(&trdata, rdata);
472 if (n == 0) {
473 return (true);
474 }
475 if (n > 0) { /* In DNSSEC order. */
476 break;
477 }
478 dns_rdata_reset(&trdata);
479 }
480 return (false);
481 }
482
483 isc_result_t
dns_rdataslab_merge(unsigned char * oslab,unsigned char * nslab,unsigned int reservelen,isc_mem_t * mctx,dns_rdataclass_t rdclass,dns_rdatatype_t type,unsigned int flags,unsigned char ** tslabp)484 dns_rdataslab_merge(unsigned char *oslab, unsigned char *nslab,
485 unsigned int reservelen, isc_mem_t *mctx,
486 dns_rdataclass_t rdclass, dns_rdatatype_t type,
487 unsigned int flags, unsigned char **tslabp) {
488 unsigned char *ocurrent, *ostart, *ncurrent, *tstart, *tcurrent, *data;
489 unsigned int ocount, ncount, count, olength, tlength, tcount, length;
490 dns_rdata_t ordata = DNS_RDATA_INIT;
491 dns_rdata_t nrdata = DNS_RDATA_INIT;
492 bool added_something = false;
493 unsigned int oadded = 0;
494 unsigned int nadded = 0;
495 unsigned int nncount = 0;
496 #if DNS_RDATASET_FIXED
497 unsigned int oncount;
498 unsigned int norder = 0;
499 unsigned int oorder = 0;
500 unsigned char *offsetbase;
501 unsigned int *offsettable;
502 #endif /* if DNS_RDATASET_FIXED */
503
504 /*
505 * XXX Need parameter to allow "delete rdatasets in nslab" merge,
506 * or perhaps another merge routine for this purpose.
507 */
508
509 REQUIRE(tslabp != NULL && *tslabp == NULL);
510 REQUIRE(oslab != NULL && nslab != NULL);
511
512 ocurrent = oslab + reservelen;
513 ocount = *ocurrent++ * 256;
514 ocount += *ocurrent++;
515 #if DNS_RDATASET_FIXED
516 ocurrent += (4 * ocount);
517 #endif /* if DNS_RDATASET_FIXED */
518 ostart = ocurrent;
519 ncurrent = nslab + reservelen;
520 ncount = *ncurrent++ * 256;
521 ncount += *ncurrent++;
522 #if DNS_RDATASET_FIXED
523 ncurrent += (4 * ncount);
524 #endif /* if DNS_RDATASET_FIXED */
525 INSIST(ocount > 0 && ncount > 0);
526
527 #if DNS_RDATASET_FIXED
528 oncount = ncount;
529 #endif /* if DNS_RDATASET_FIXED */
530
531 /*
532 * Yes, this is inefficient!
533 */
534
535 /*
536 * Figure out the length of the old slab's data.
537 */
538 olength = 0;
539 for (count = 0; count < ocount; count++) {
540 length = *ocurrent++ * 256;
541 length += *ocurrent++;
542 #if DNS_RDATASET_FIXED
543 olength += length + 8;
544 ocurrent += length + 2;
545 #else /* if DNS_RDATASET_FIXED */
546 olength += length + 2;
547 ocurrent += length;
548 #endif /* if DNS_RDATASET_FIXED */
549 }
550
551 /*
552 * Start figuring out the target length and count.
553 */
554 tlength = reservelen + 2 + olength;
555 tcount = ocount;
556
557 /*
558 * Add in the length of rdata in the new slab that aren't in
559 * the old slab.
560 */
561 do {
562 dns_rdata_init(&nrdata);
563 rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
564 if (!rdata_in_slab(oslab, reservelen, rdclass, type, &nrdata)) {
565 /*
566 * This rdata isn't in the old slab.
567 */
568 #if DNS_RDATASET_FIXED
569 tlength += nrdata.length + 8;
570 #else /* if DNS_RDATASET_FIXED */
571 tlength += nrdata.length + 2;
572 #endif /* if DNS_RDATASET_FIXED */
573 if (type == dns_rdatatype_rrsig) {
574 tlength++;
575 }
576 tcount++;
577 nncount++;
578 added_something = true;
579 }
580 ncount--;
581 } while (ncount > 0);
582 ncount = nncount;
583
584 if (((flags & DNS_RDATASLAB_EXACT) != 0) && (tcount != ncount + ocount))
585 {
586 return (DNS_R_NOTEXACT);
587 }
588
589 if (!added_something && (flags & DNS_RDATASLAB_FORCE) == 0) {
590 return (DNS_R_UNCHANGED);
591 }
592
593 /*
594 * Ensure that singleton types are actually singletons.
595 */
596 if (tcount > 1 && dns_rdatatype_issingleton(type)) {
597 /*
598 * We have a singleton type, but there's more than one
599 * RR in the rdataset.
600 */
601 return (DNS_R_SINGLETON);
602 }
603
604 if (tcount > 0xffff) {
605 return (ISC_R_NOSPACE);
606 }
607
608 /*
609 * Copy the reserved area from the new slab.
610 */
611 tstart = isc_mem_get(mctx, tlength);
612 memmove(tstart, nslab, reservelen);
613 tcurrent = tstart + reservelen;
614 #if DNS_RDATASET_FIXED
615 offsetbase = tcurrent;
616 #endif /* if DNS_RDATASET_FIXED */
617
618 /*
619 * Write the new count.
620 */
621 *tcurrent++ = (tcount & 0xff00) >> 8;
622 *tcurrent++ = (tcount & 0x00ff);
623
624 #if DNS_RDATASET_FIXED
625 /*
626 * Skip offset table.
627 */
628 tcurrent += (tcount * 4);
629
630 offsettable = isc_mem_get(mctx,
631 (ocount + oncount) * sizeof(unsigned int));
632 memset(offsettable, 0, (ocount + oncount) * sizeof(unsigned int));
633 #endif /* if DNS_RDATASET_FIXED */
634
635 /*
636 * Merge the two slabs.
637 */
638 ocurrent = ostart;
639 INSIST(ocount != 0);
640 #if DNS_RDATASET_FIXED
641 oorder = ocurrent[2] * 256 + ocurrent[3];
642 INSIST(oorder < ocount);
643 #endif /* if DNS_RDATASET_FIXED */
644 rdata_from_slab(&ocurrent, rdclass, type, &ordata);
645
646 ncurrent = nslab + reservelen + 2;
647 #if DNS_RDATASET_FIXED
648 ncurrent += (4 * oncount);
649 #endif /* if DNS_RDATASET_FIXED */
650
651 if (ncount > 0) {
652 do {
653 dns_rdata_reset(&nrdata);
654 #if DNS_RDATASET_FIXED
655 norder = ncurrent[2] * 256 + ncurrent[3];
656
657 INSIST(norder < oncount);
658 #endif /* if DNS_RDATASET_FIXED */
659 rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
660 } while (rdata_in_slab(oslab, reservelen, rdclass, type,
661 &nrdata));
662 }
663
664 while (oadded < ocount || nadded < ncount) {
665 bool fromold;
666 if (oadded == ocount) {
667 fromold = false;
668 } else if (nadded == ncount) {
669 fromold = true;
670 } else {
671 fromold = (dns_rdata_compare(&ordata, &nrdata) < 0);
672 }
673 if (fromold) {
674 #if DNS_RDATASET_FIXED
675 offsettable[oorder] = tcurrent - offsetbase;
676 #endif /* if DNS_RDATASET_FIXED */
677 length = ordata.length;
678 data = ordata.data;
679 if (type == dns_rdatatype_rrsig) {
680 length++;
681 data--;
682 }
683 *tcurrent++ = (length & 0xff00) >> 8;
684 *tcurrent++ = (length & 0x00ff);
685 #if DNS_RDATASET_FIXED
686 tcurrent += 2; /* fill in later */
687 #endif /* if DNS_RDATASET_FIXED */
688 memmove(tcurrent, data, length);
689 tcurrent += length;
690 oadded++;
691 if (oadded < ocount) {
692 dns_rdata_reset(&ordata);
693 #if DNS_RDATASET_FIXED
694 oorder = ocurrent[2] * 256 + ocurrent[3];
695 INSIST(oorder < ocount);
696 #endif /* if DNS_RDATASET_FIXED */
697 rdata_from_slab(&ocurrent, rdclass, type,
698 &ordata);
699 }
700 } else {
701 #if DNS_RDATASET_FIXED
702 offsettable[ocount + norder] = tcurrent - offsetbase;
703 #endif /* if DNS_RDATASET_FIXED */
704 length = nrdata.length;
705 data = nrdata.data;
706 if (type == dns_rdatatype_rrsig) {
707 length++;
708 data--;
709 }
710 *tcurrent++ = (length & 0xff00) >> 8;
711 *tcurrent++ = (length & 0x00ff);
712 #if DNS_RDATASET_FIXED
713 tcurrent += 2; /* fill in later */
714 #endif /* if DNS_RDATASET_FIXED */
715 memmove(tcurrent, data, length);
716 tcurrent += length;
717 nadded++;
718 if (nadded < ncount) {
719 do {
720 dns_rdata_reset(&nrdata);
721 #if DNS_RDATASET_FIXED
722 norder = ncurrent[2] * 256 +
723 ncurrent[3];
724 INSIST(norder < oncount);
725 #endif /* if DNS_RDATASET_FIXED */
726 rdata_from_slab(&ncurrent, rdclass,
727 type, &nrdata);
728 } while (rdata_in_slab(oslab, reservelen,
729 rdclass, type, &nrdata));
730 }
731 }
732 }
733
734 #if DNS_RDATASET_FIXED
735 fillin_offsets(offsetbase, offsettable, ocount + oncount);
736
737 isc_mem_put(mctx, offsettable,
738 (ocount + oncount) * sizeof(unsigned int));
739 #endif /* if DNS_RDATASET_FIXED */
740
741 INSIST(tcurrent == tstart + tlength);
742
743 *tslabp = tstart;
744
745 return (ISC_R_SUCCESS);
746 }
747
748 isc_result_t
dns_rdataslab_subtract(unsigned char * mslab,unsigned char * sslab,unsigned int reservelen,isc_mem_t * mctx,dns_rdataclass_t rdclass,dns_rdatatype_t type,unsigned int flags,unsigned char ** tslabp)749 dns_rdataslab_subtract(unsigned char *mslab, unsigned char *sslab,
750 unsigned int reservelen, isc_mem_t *mctx,
751 dns_rdataclass_t rdclass, dns_rdatatype_t type,
752 unsigned int flags, unsigned char **tslabp) {
753 unsigned char *mcurrent, *sstart, *scurrent, *tstart, *tcurrent;
754 unsigned int mcount, scount, rcount, count, tlength, tcount, i;
755 dns_rdata_t srdata = DNS_RDATA_INIT;
756 dns_rdata_t mrdata = DNS_RDATA_INIT;
757 #if DNS_RDATASET_FIXED
758 unsigned char *offsetbase;
759 unsigned int *offsettable;
760 unsigned int order;
761 #endif /* if DNS_RDATASET_FIXED */
762
763 REQUIRE(tslabp != NULL && *tslabp == NULL);
764 REQUIRE(mslab != NULL && sslab != NULL);
765
766 mcurrent = mslab + reservelen;
767 mcount = *mcurrent++ * 256;
768 mcount += *mcurrent++;
769 scurrent = sslab + reservelen;
770 scount = *scurrent++ * 256;
771 scount += *scurrent++;
772 INSIST(mcount > 0 && scount > 0);
773
774 /*
775 * Yes, this is inefficient!
776 */
777
778 /*
779 * Start figuring out the target length and count.
780 */
781 tlength = reservelen + 2;
782 tcount = 0;
783 rcount = 0;
784
785 #if DNS_RDATASET_FIXED
786 mcurrent += 4 * mcount;
787 scurrent += 4 * scount;
788 #endif /* if DNS_RDATASET_FIXED */
789 sstart = scurrent;
790
791 /*
792 * Add in the length of rdata in the mslab that aren't in
793 * the sslab.
794 */
795 for (i = 0; i < mcount; i++) {
796 unsigned char *mrdatabegin = mcurrent;
797 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
798 scurrent = sstart;
799 for (count = 0; count < scount; count++) {
800 dns_rdata_reset(&srdata);
801 rdata_from_slab(&scurrent, rdclass, type, &srdata);
802 if (dns_rdata_compare(&mrdata, &srdata) == 0) {
803 break;
804 }
805 }
806 if (count == scount) {
807 /*
808 * This rdata isn't in the sslab, and thus isn't
809 * being subtracted.
810 */
811 tlength += (unsigned int)(mcurrent - mrdatabegin);
812 tcount++;
813 } else {
814 rcount++;
815 }
816 dns_rdata_reset(&mrdata);
817 }
818
819 #if DNS_RDATASET_FIXED
820 tlength += (4 * tcount);
821 #endif /* if DNS_RDATASET_FIXED */
822
823 /*
824 * Check that all the records originally existed. The numeric
825 * check only works as rdataslabs do not contain duplicates.
826 */
827 if (((flags & DNS_RDATASLAB_EXACT) != 0) && (rcount != scount)) {
828 return (DNS_R_NOTEXACT);
829 }
830
831 /*
832 * Don't continue if the new rdataslab would be empty.
833 */
834 if (tcount == 0) {
835 return (DNS_R_NXRRSET);
836 }
837
838 /*
839 * If nothing is going to change, we can stop.
840 */
841 if (rcount == 0) {
842 return (DNS_R_UNCHANGED);
843 }
844
845 /*
846 * Copy the reserved area from the mslab.
847 */
848 tstart = isc_mem_get(mctx, tlength);
849 memmove(tstart, mslab, reservelen);
850 tcurrent = tstart + reservelen;
851 #if DNS_RDATASET_FIXED
852 offsetbase = tcurrent;
853
854 offsettable = isc_mem_get(mctx, mcount * sizeof(unsigned int));
855 memset(offsettable, 0, mcount * sizeof(unsigned int));
856 #endif /* if DNS_RDATASET_FIXED */
857
858 /*
859 * Write the new count.
860 */
861 *tcurrent++ = (tcount & 0xff00) >> 8;
862 *tcurrent++ = (tcount & 0x00ff);
863
864 #if DNS_RDATASET_FIXED
865 tcurrent += (4 * tcount);
866 #endif /* if DNS_RDATASET_FIXED */
867
868 /*
869 * Copy the parts of mslab not in sslab.
870 */
871 mcurrent = mslab + reservelen;
872 mcount = *mcurrent++ * 256;
873 mcount += *mcurrent++;
874 #if DNS_RDATASET_FIXED
875 mcurrent += (4 * mcount);
876 #endif /* if DNS_RDATASET_FIXED */
877 for (i = 0; i < mcount; i++) {
878 unsigned char *mrdatabegin = mcurrent;
879 #if DNS_RDATASET_FIXED
880 order = mcurrent[2] * 256 + mcurrent[3];
881 INSIST(order < mcount);
882 #endif /* if DNS_RDATASET_FIXED */
883 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
884 scurrent = sstart;
885 for (count = 0; count < scount; count++) {
886 dns_rdata_reset(&srdata);
887 rdata_from_slab(&scurrent, rdclass, type, &srdata);
888 if (dns_rdata_compare(&mrdata, &srdata) == 0) {
889 break;
890 }
891 }
892 if (count == scount) {
893 /*
894 * This rdata isn't in the sslab, and thus should be
895 * copied to the tslab.
896 */
897 unsigned int length;
898 length = (unsigned int)(mcurrent - mrdatabegin);
899 #if DNS_RDATASET_FIXED
900 offsettable[order] = tcurrent - offsetbase;
901 #endif /* if DNS_RDATASET_FIXED */
902 memmove(tcurrent, mrdatabegin, length);
903 tcurrent += length;
904 }
905 dns_rdata_reset(&mrdata);
906 }
907
908 #if DNS_RDATASET_FIXED
909 fillin_offsets(offsetbase, offsettable, mcount);
910
911 isc_mem_put(mctx, offsettable, mcount * sizeof(unsigned int));
912 #endif /* if DNS_RDATASET_FIXED */
913
914 INSIST(tcurrent == tstart + tlength);
915
916 *tslabp = tstart;
917
918 return (ISC_R_SUCCESS);
919 }
920
921 bool
dns_rdataslab_equal(unsigned char * slab1,unsigned char * slab2,unsigned int reservelen)922 dns_rdataslab_equal(unsigned char *slab1, unsigned char *slab2,
923 unsigned int reservelen) {
924 unsigned char *current1, *current2;
925 unsigned int count1, count2;
926 unsigned int length1, length2;
927
928 current1 = slab1 + reservelen;
929 count1 = *current1++ * 256;
930 count1 += *current1++;
931
932 current2 = slab2 + reservelen;
933 count2 = *current2++ * 256;
934 count2 += *current2++;
935
936 if (count1 != count2) {
937 return (false);
938 }
939
940 #if DNS_RDATASET_FIXED
941 current1 += (4 * count1);
942 current2 += (4 * count2);
943 #endif /* if DNS_RDATASET_FIXED */
944
945 while (count1 > 0) {
946 length1 = *current1++ * 256;
947 length1 += *current1++;
948
949 length2 = *current2++ * 256;
950 length2 += *current2++;
951
952 #if DNS_RDATASET_FIXED
953 current1 += 2;
954 current2 += 2;
955 #endif /* if DNS_RDATASET_FIXED */
956
957 if (length1 != length2 ||
958 memcmp(current1, current2, length1) != 0)
959 {
960 return (false);
961 }
962
963 current1 += length1;
964 current2 += length1;
965
966 count1--;
967 }
968 return (true);
969 }
970
971 bool
dns_rdataslab_equalx(unsigned char * slab1,unsigned char * slab2,unsigned int reservelen,dns_rdataclass_t rdclass,dns_rdatatype_t type)972 dns_rdataslab_equalx(unsigned char *slab1, unsigned char *slab2,
973 unsigned int reservelen, dns_rdataclass_t rdclass,
974 dns_rdatatype_t type) {
975 unsigned char *current1, *current2;
976 unsigned int count1, count2;
977 dns_rdata_t rdata1 = DNS_RDATA_INIT;
978 dns_rdata_t rdata2 = DNS_RDATA_INIT;
979
980 current1 = slab1 + reservelen;
981 count1 = *current1++ * 256;
982 count1 += *current1++;
983
984 current2 = slab2 + reservelen;
985 count2 = *current2++ * 256;
986 count2 += *current2++;
987
988 if (count1 != count2) {
989 return (false);
990 }
991
992 #if DNS_RDATASET_FIXED
993 current1 += (4 * count1);
994 current2 += (4 * count2);
995 #endif /* if DNS_RDATASET_FIXED */
996
997 while (count1-- > 0) {
998 rdata_from_slab(¤t1, rdclass, type, &rdata1);
999 rdata_from_slab(¤t2, rdclass, type, &rdata2);
1000 if (dns_rdata_compare(&rdata1, &rdata2) != 0) {
1001 return (false);
1002 }
1003 dns_rdata_reset(&rdata1);
1004 dns_rdata_reset(&rdata2);
1005 }
1006 return (true);
1007 }
1008