xref: /netbsd-src/external/mpl/bind/dist/lib/dns/diff.c (revision bcda20f65a8566e103791ec395f7f499ef322704)
1 /*	$NetBSD: diff.c,v 1.10 2025/01/26 16:25:22 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 <inttypes.h>
19 #include <stdbool.h>
20 #include <stddef.h>
21 #include <stdlib.h>
22 
23 #include <isc/buffer.h>
24 #include <isc/file.h>
25 #include <isc/mem.h>
26 #include <isc/result.h>
27 #include <isc/string.h>
28 #include <isc/util.h>
29 
30 #include <dns/callbacks.h>
31 #include <dns/db.h>
32 #include <dns/diff.h>
33 #include <dns/log.h>
34 #include <dns/rdataclass.h>
35 #include <dns/rdatalist.h>
36 #include <dns/rdataset.h>
37 #include <dns/rdatastruct.h>
38 #include <dns/rdatatype.h>
39 #include <dns/time.h>
40 
41 #define CHECK(op)                            \
42 	do {                                 \
43 		result = (op);               \
44 		if (result != ISC_R_SUCCESS) \
45 			goto failure;        \
46 	} while (0)
47 
48 #define DIFF_COMMON_LOGARGS \
49 	dns_lctx, DNS_LOGCATEGORY_GENERAL, DNS_LOGMODULE_DIFF
50 
51 static dns_rdatatype_t
52 rdata_covers(dns_rdata_t *rdata) {
53 	return rdata->type == dns_rdatatype_rrsig ? dns_rdata_covers(rdata) : 0;
54 }
55 
56 isc_result_t
57 dns_difftuple_create(isc_mem_t *mctx, dns_diffop_t op, const dns_name_t *name,
58 		     dns_ttl_t ttl, dns_rdata_t *rdata, dns_difftuple_t **tp) {
59 	dns_difftuple_t *t;
60 	unsigned int size;
61 	unsigned char *datap;
62 
63 	REQUIRE(tp != NULL && *tp == NULL);
64 
65 	/*
66 	 * Create a new tuple.  The variable-size wire-format name data and
67 	 * rdata immediately follow the dns_difftuple_t structure
68 	 * in memory.
69 	 */
70 	size = sizeof(*t) + name->length + rdata->length;
71 	t = isc_mem_allocate(mctx, size);
72 	t->mctx = NULL;
73 	isc_mem_attach(mctx, &t->mctx);
74 	t->op = op;
75 
76 	datap = (unsigned char *)(t + 1);
77 
78 	memmove(datap, name->ndata, name->length);
79 	dns_name_init(&t->name, NULL);
80 	dns_name_clone(name, &t->name);
81 	t->name.ndata = datap;
82 	datap += name->length;
83 
84 	t->ttl = ttl;
85 
86 	dns_rdata_init(&t->rdata);
87 	dns_rdata_clone(rdata, &t->rdata);
88 	if (rdata->data != NULL) {
89 		memmove(datap, rdata->data, rdata->length);
90 		t->rdata.data = datap;
91 		datap += rdata->length;
92 	} else {
93 		t->rdata.data = NULL;
94 		INSIST(rdata->length == 0);
95 	}
96 
97 	ISC_LINK_INIT(&t->rdata, link);
98 	ISC_LINK_INIT(t, link);
99 	t->magic = DNS_DIFFTUPLE_MAGIC;
100 
101 	INSIST(datap == (unsigned char *)t + size);
102 
103 	*tp = t;
104 	return ISC_R_SUCCESS;
105 }
106 
107 void
108 dns_difftuple_free(dns_difftuple_t **tp) {
109 	dns_difftuple_t *t = *tp;
110 	*tp = NULL;
111 	isc_mem_t *mctx;
112 
113 	REQUIRE(DNS_DIFFTUPLE_VALID(t));
114 
115 	dns_name_invalidate(&t->name);
116 	t->magic = 0;
117 	mctx = t->mctx;
118 	isc_mem_free(mctx, t);
119 	isc_mem_detach(&mctx);
120 }
121 
122 isc_result_t
123 dns_difftuple_copy(dns_difftuple_t *orig, dns_difftuple_t **copyp) {
124 	return dns_difftuple_create(orig->mctx, orig->op, &orig->name,
125 				    orig->ttl, &orig->rdata, copyp);
126 }
127 
128 void
129 dns_diff_init(isc_mem_t *mctx, dns_diff_t *diff) {
130 	diff->mctx = mctx;
131 	ISC_LIST_INIT(diff->tuples);
132 	diff->magic = DNS_DIFF_MAGIC;
133 	diff->size = 0;
134 }
135 
136 void
137 dns_diff_clear(dns_diff_t *diff) {
138 	dns_difftuple_t *t;
139 	REQUIRE(DNS_DIFF_VALID(diff));
140 	while ((t = ISC_LIST_HEAD(diff->tuples)) != NULL) {
141 		ISC_LIST_UNLINK(diff->tuples, t, link);
142 		dns_difftuple_free(&t);
143 	}
144 	diff->size = 0;
145 	ENSURE(ISC_LIST_EMPTY(diff->tuples));
146 }
147 
148 void
149 dns_diff_append(dns_diff_t *diff, dns_difftuple_t **tuplep) {
150 	REQUIRE(DNS_DIFF_VALID(diff));
151 	ISC_LIST_APPEND(diff->tuples, *tuplep, link);
152 	diff->size += 1;
153 	*tuplep = NULL;
154 }
155 
156 bool
157 dns_diff_is_boundary(const dns_diff_t *diff, dns_name_t *new_name) {
158 	REQUIRE(DNS_DIFF_VALID(diff));
159 	REQUIRE(DNS_NAME_VALID(new_name));
160 
161 	if (ISC_LIST_EMPTY(diff->tuples)) {
162 		return false;
163 	}
164 
165 	dns_difftuple_t *tail = ISC_LIST_TAIL(diff->tuples);
166 	return !dns_name_caseequal(&tail->name, new_name);
167 }
168 
169 size_t
170 dns_diff_size(const dns_diff_t *diff) {
171 	REQUIRE(DNS_DIFF_VALID(diff));
172 	return diff->size;
173 }
174 
175 /* XXX this is O(N) */
176 
177 void
178 dns_diff_appendminimal(dns_diff_t *diff, dns_difftuple_t **tuplep) {
179 	dns_difftuple_t *ot, *next_ot;
180 
181 	REQUIRE(DNS_DIFF_VALID(diff));
182 	REQUIRE(DNS_DIFFTUPLE_VALID(*tuplep));
183 
184 	/*
185 	 * Look for an existing tuple with the same owner name,
186 	 * rdata, and TTL.   If we are doing an addition and find a
187 	 * deletion or vice versa, remove both the old and the
188 	 * new tuple since they cancel each other out (assuming
189 	 * that we never delete nonexistent data or add existing
190 	 * data).
191 	 *
192 	 * If we find an old update of the same kind as
193 	 * the one we are doing, there must be a programming
194 	 * error.  We report it but try to continue anyway.
195 	 */
196 	for (ot = ISC_LIST_HEAD(diff->tuples); ot != NULL; ot = next_ot) {
197 		next_ot = ISC_LIST_NEXT(ot, link);
198 		if (dns_name_caseequal(&ot->name, &(*tuplep)->name) &&
199 		    dns_rdata_compare(&ot->rdata, &(*tuplep)->rdata) == 0 &&
200 		    ot->ttl == (*tuplep)->ttl)
201 		{
202 			ISC_LIST_UNLINK(diff->tuples, ot, link);
203 			INSIST(diff->size > 0);
204 			diff->size -= 1;
205 
206 			if ((*tuplep)->op == ot->op) {
207 				UNEXPECTED_ERROR("unexpected non-minimal diff");
208 			} else {
209 				dns_difftuple_free(tuplep);
210 			}
211 			dns_difftuple_free(&ot);
212 			break;
213 		}
214 	}
215 
216 	if (*tuplep != NULL) {
217 		ISC_LIST_APPEND(diff->tuples, *tuplep, link);
218 		diff->size += 1;
219 		*tuplep = NULL;
220 	}
221 }
222 
223 static isc_stdtime_t
224 setresign(dns_rdataset_t *modified) {
225 	dns_rdata_t rdata = DNS_RDATA_INIT;
226 	dns_rdata_rrsig_t sig;
227 	int64_t when;
228 	isc_result_t result;
229 
230 	result = dns_rdataset_first(modified);
231 	INSIST(result == ISC_R_SUCCESS);
232 	dns_rdataset_current(modified, &rdata);
233 	(void)dns_rdata_tostruct(&rdata, &sig, NULL);
234 	if ((rdata.flags & DNS_RDATA_OFFLINE) != 0) {
235 		when = 0;
236 	} else {
237 		when = dns_time64_from32(sig.timeexpire);
238 	}
239 	dns_rdata_reset(&rdata);
240 
241 	result = dns_rdataset_next(modified);
242 	while (result == ISC_R_SUCCESS) {
243 		dns_rdataset_current(modified, &rdata);
244 		(void)dns_rdata_tostruct(&rdata, &sig, NULL);
245 		if ((rdata.flags & DNS_RDATA_OFFLINE) != 0) {
246 			goto next_rr;
247 		}
248 		if (when == 0 || dns_time64_from32(sig.timeexpire) < when) {
249 			when = dns_time64_from32(sig.timeexpire);
250 		}
251 	next_rr:
252 		dns_rdata_reset(&rdata);
253 		result = dns_rdataset_next(modified);
254 	}
255 	INSIST(result == ISC_R_NOMORE);
256 	return (isc_stdtime_t)when;
257 }
258 
259 static void
260 getownercase(dns_rdataset_t *rdataset, dns_name_t *name) {
261 	if (dns_rdataset_isassociated(rdataset)) {
262 		dns_rdataset_getownercase(rdataset, name);
263 	}
264 }
265 
266 static void
267 setownercase(dns_rdataset_t *rdataset, const dns_name_t *name) {
268 	if (dns_rdataset_isassociated(rdataset)) {
269 		dns_rdataset_setownercase(rdataset, name);
270 	}
271 }
272 
273 static const char *
274 optotext(dns_diffop_t op) {
275 	switch (op) {
276 	case DNS_DIFFOP_ADD:
277 		return "add";
278 	case DNS_DIFFOP_ADDRESIGN:
279 		return "add-resign";
280 	case DNS_DIFFOP_DEL:
281 		return "del";
282 	case DNS_DIFFOP_DELRESIGN:
283 		return "del-resign";
284 	default:
285 		return "unknown";
286 	}
287 }
288 
289 static isc_result_t
290 diff_apply(const dns_diff_t *diff, dns_db_t *db, dns_dbversion_t *ver,
291 	   bool warn) {
292 	dns_difftuple_t *t;
293 	dns_dbnode_t *node = NULL;
294 	isc_result_t result;
295 	char namebuf[DNS_NAME_FORMATSIZE];
296 	char typebuf[DNS_RDATATYPE_FORMATSIZE];
297 	char classbuf[DNS_RDATACLASS_FORMATSIZE];
298 
299 	REQUIRE(DNS_DIFF_VALID(diff));
300 	REQUIRE(DNS_DB_VALID(db));
301 
302 	t = ISC_LIST_HEAD(diff->tuples);
303 	while (t != NULL) {
304 		dns_name_t *name;
305 
306 		INSIST(node == NULL);
307 		name = &t->name;
308 		/*
309 		 * Find the node.
310 		 * We create the node if it does not exist.
311 		 * This will cause an empty node to be created if the diff
312 		 * contains a deletion of an RR at a nonexistent name,
313 		 * but such diffs should never be created in the first
314 		 * place.
315 		 */
316 
317 		while (t != NULL && dns_name_equal(&t->name, name)) {
318 			dns_rdatatype_t type, covers;
319 			dns_rdataclass_t rdclass;
320 			dns_diffop_t op;
321 			dns_rdatalist_t rdl;
322 			dns_rdataset_t rds;
323 			dns_rdataset_t ardataset;
324 			unsigned int options;
325 
326 			op = t->op;
327 			type = t->rdata.type;
328 			rdclass = t->rdata.rdclass;
329 			covers = rdata_covers(&t->rdata);
330 
331 			/*
332 			 * Collect a contiguous set of updates with
333 			 * the same operation (add/delete) and RR type
334 			 * into a single rdatalist so that the
335 			 * database rrset merging/subtraction code
336 			 * can work more efficiently than if each
337 			 * RR were merged into / subtracted from
338 			 * the database separately.
339 			 *
340 			 * This is done by linking rdata structures from the
341 			 * diff into "rdatalist".  This uses the rdata link
342 			 * field, not the diff link field, so the structure
343 			 * of the diff itself is not affected.
344 			 */
345 
346 			dns_rdatalist_init(&rdl);
347 			rdl.type = type;
348 			rdl.covers = covers;
349 			rdl.rdclass = t->rdata.rdclass;
350 			rdl.ttl = t->ttl;
351 
352 			node = NULL;
353 			if (type != dns_rdatatype_nsec3 &&
354 			    covers != dns_rdatatype_nsec3)
355 			{
356 				CHECK(dns_db_findnode(db, name, true, &node));
357 			} else {
358 				CHECK(dns_db_findnsec3node(db, name, true,
359 							   &node));
360 			}
361 
362 			while (t != NULL && dns_name_equal(&t->name, name) &&
363 			       t->op == op && t->rdata.type == type &&
364 			       rdata_covers(&t->rdata) == covers)
365 			{
366 				/*
367 				 * Remember the add name for
368 				 * dns_rdataset_setownercase.
369 				 */
370 				name = &t->name;
371 				if (t->ttl != rdl.ttl && warn) {
372 					dns_name_format(name, namebuf,
373 							sizeof(namebuf));
374 					dns_rdatatype_format(t->rdata.type,
375 							     typebuf,
376 							     sizeof(typebuf));
377 					dns_rdataclass_format(t->rdata.rdclass,
378 							      classbuf,
379 							      sizeof(classbuf));
380 					isc_log_write(DIFF_COMMON_LOGARGS,
381 						      ISC_LOG_WARNING,
382 						      "'%s/%s/%s': TTL differs "
383 						      "in "
384 						      "rdataset, adjusting "
385 						      "%lu -> %lu",
386 						      namebuf, typebuf,
387 						      classbuf,
388 						      (unsigned long)t->ttl,
389 						      (unsigned long)rdl.ttl);
390 				}
391 				ISC_LIST_APPEND(rdl.rdata, &t->rdata, link);
392 				t = ISC_LIST_NEXT(t, link);
393 			}
394 
395 			/*
396 			 * Convert the rdatalist into a rdataset.
397 			 */
398 			dns_rdataset_init(&rds);
399 			dns_rdataset_init(&ardataset);
400 			dns_rdatalist_tordataset(&rdl, &rds);
401 			rds.trust = dns_trust_ultimate;
402 
403 			/*
404 			 * Merge the rdataset into the database.
405 			 */
406 			switch (op) {
407 			case DNS_DIFFOP_ADD:
408 			case DNS_DIFFOP_ADDRESIGN:
409 				options = DNS_DBADD_MERGE | DNS_DBADD_EXACT |
410 					  DNS_DBADD_EXACTTTL;
411 				result = dns_db_addrdataset(db, node, ver, 0,
412 							    &rds, options,
413 							    &ardataset);
414 				break;
415 			case DNS_DIFFOP_DEL:
416 			case DNS_DIFFOP_DELRESIGN:
417 				options = DNS_DBSUB_EXACT | DNS_DBSUB_WANTOLD;
418 				result = dns_db_subtractrdataset(db, node, ver,
419 								 &rds, options,
420 								 &ardataset);
421 				break;
422 			default:
423 				UNREACHABLE();
424 			}
425 
426 			if (result == ISC_R_SUCCESS) {
427 				if (rds.type == dns_rdatatype_rrsig &&
428 				    (op == DNS_DIFFOP_DELRESIGN ||
429 				     op == DNS_DIFFOP_ADDRESIGN))
430 				{
431 					isc_stdtime_t resign;
432 					resign = setresign(&ardataset);
433 					dns_db_setsigningtime(db, &ardataset,
434 							      resign);
435 				}
436 				if (op == DNS_DIFFOP_ADD ||
437 				    op == DNS_DIFFOP_ADDRESIGN)
438 				{
439 					setownercase(&ardataset, name);
440 				}
441 				if (op == DNS_DIFFOP_DEL ||
442 				    op == DNS_DIFFOP_DELRESIGN)
443 				{
444 					getownercase(&ardataset, name);
445 				}
446 			} else if (result == DNS_R_UNCHANGED) {
447 				/*
448 				 * This will not happen when executing a
449 				 * dynamic update, because that code will
450 				 * generate strictly minimal diffs.
451 				 * It may happen when receiving an IXFR
452 				 * from a server that is not as careful.
453 				 * Issue a warning and continue.
454 				 */
455 				if (warn) {
456 					dns_name_format(dns_db_origin(db),
457 							namebuf,
458 							sizeof(namebuf));
459 					dns_rdataclass_format(dns_db_class(db),
460 							      classbuf,
461 							      sizeof(classbuf));
462 					isc_log_write(DIFF_COMMON_LOGARGS,
463 						      ISC_LOG_WARNING,
464 						      "%s/%s: dns_diff_apply: "
465 						      "update with no effect",
466 						      namebuf, classbuf);
467 				}
468 				if (op == DNS_DIFFOP_ADD ||
469 				    op == DNS_DIFFOP_ADDRESIGN)
470 				{
471 					setownercase(&ardataset, name);
472 				}
473 				if (op == DNS_DIFFOP_DEL ||
474 				    op == DNS_DIFFOP_DELRESIGN)
475 				{
476 					getownercase(&ardataset, name);
477 				}
478 			} else if (result == DNS_R_NXRRSET) {
479 				/*
480 				 * OK.
481 				 */
482 				if (op == DNS_DIFFOP_DEL ||
483 				    op == DNS_DIFFOP_DELRESIGN)
484 				{
485 					getownercase(&ardataset, name);
486 				}
487 				if (dns_rdataset_isassociated(&ardataset)) {
488 					dns_rdataset_disassociate(&ardataset);
489 				}
490 			} else {
491 				if (result == DNS_R_NOTEXACT) {
492 					dns_name_format(name, namebuf,
493 							sizeof(namebuf));
494 					dns_rdatatype_format(type, typebuf,
495 							     sizeof(typebuf));
496 					dns_rdataclass_format(rdclass, classbuf,
497 							      sizeof(classbuf));
498 					isc_log_write(
499 						DIFF_COMMON_LOGARGS,
500 						ISC_LOG_ERROR,
501 						"dns_diff_apply: %s/%s/%s: %s "
502 						"%s",
503 						namebuf, typebuf, classbuf,
504 						optotext(op),
505 						isc_result_totext(result));
506 				}
507 				if (dns_rdataset_isassociated(&ardataset)) {
508 					dns_rdataset_disassociate(&ardataset);
509 				}
510 				CHECK(result);
511 			}
512 			dns_db_detachnode(db, &node);
513 			if (dns_rdataset_isassociated(&ardataset)) {
514 				dns_rdataset_disassociate(&ardataset);
515 			}
516 		}
517 	}
518 	return ISC_R_SUCCESS;
519 
520 failure:
521 	if (node != NULL) {
522 		dns_db_detachnode(db, &node);
523 	}
524 	return result;
525 }
526 
527 isc_result_t
528 dns_diff_apply(const dns_diff_t *diff, dns_db_t *db, dns_dbversion_t *ver) {
529 	return diff_apply(diff, db, ver, true);
530 }
531 
532 isc_result_t
533 dns_diff_applysilently(const dns_diff_t *diff, dns_db_t *db,
534 		       dns_dbversion_t *ver) {
535 	return diff_apply(diff, db, ver, false);
536 }
537 
538 /* XXX this duplicates lots of code in diff_apply(). */
539 
540 isc_result_t
541 dns_diff_load(const dns_diff_t *diff, dns_rdatacallbacks_t *callbacks) {
542 	dns_difftuple_t *t;
543 	isc_result_t result;
544 
545 	REQUIRE(DNS_DIFF_VALID(diff));
546 
547 	if (callbacks->setup != NULL) {
548 		callbacks->setup(callbacks->add_private);
549 	}
550 
551 	t = ISC_LIST_HEAD(diff->tuples);
552 	while (t != NULL) {
553 		dns_name_t *name;
554 
555 		name = &t->name;
556 		while (t != NULL && dns_name_caseequal(&t->name, name)) {
557 			dns_rdatatype_t type, covers;
558 			dns_diffop_t op;
559 			dns_rdatalist_t rdl;
560 			dns_rdataset_t rds;
561 
562 			op = t->op;
563 			type = t->rdata.type;
564 			covers = rdata_covers(&t->rdata);
565 
566 			dns_rdatalist_init(&rdl);
567 			rdl.type = type;
568 			rdl.covers = covers;
569 			rdl.rdclass = t->rdata.rdclass;
570 			rdl.ttl = t->ttl;
571 
572 			while (t != NULL &&
573 			       dns_name_caseequal(&t->name, name) &&
574 			       t->op == op && t->rdata.type == type &&
575 			       rdata_covers(&t->rdata) == covers)
576 			{
577 				ISC_LIST_APPEND(rdl.rdata, &t->rdata, link);
578 				t = ISC_LIST_NEXT(t, link);
579 			}
580 
581 			/*
582 			 * Convert the rdatalist into a rdataset.
583 			 */
584 			dns_rdataset_init(&rds);
585 			dns_rdatalist_tordataset(&rdl, &rds);
586 			rds.trust = dns_trust_ultimate;
587 
588 			INSIST(op == DNS_DIFFOP_ADD);
589 			result = callbacks->add(callbacks->add_private, name,
590 						&rds DNS__DB_FILELINE);
591 			if (result == DNS_R_UNCHANGED) {
592 				isc_log_write(DIFF_COMMON_LOGARGS,
593 					      ISC_LOG_WARNING,
594 					      "dns_diff_load: "
595 					      "update with no effect");
596 			} else if (result == ISC_R_SUCCESS ||
597 				   result == DNS_R_NXRRSET)
598 			{
599 				/*
600 				 * OK.
601 				 */
602 			} else {
603 				CHECK(result);
604 			}
605 		}
606 	}
607 	result = ISC_R_SUCCESS;
608 
609 failure:
610 	if (callbacks->commit != NULL) {
611 		callbacks->commit(callbacks->add_private);
612 	}
613 	return result;
614 }
615 
616 /*
617  * XXX uses qsort(); a merge sort would be more natural for lists,
618  * and perhaps safer wrt thread stack overflow.
619  */
620 isc_result_t
621 dns_diff_sort(dns_diff_t *diff, dns_diff_compare_func *compare) {
622 	unsigned int length = 0;
623 	unsigned int i;
624 	dns_difftuple_t **v;
625 	dns_difftuple_t *p;
626 	REQUIRE(DNS_DIFF_VALID(diff));
627 
628 	for (p = ISC_LIST_HEAD(diff->tuples); p != NULL;
629 	     p = ISC_LIST_NEXT(p, link))
630 	{
631 		length++;
632 	}
633 	if (length == 0) {
634 		return ISC_R_SUCCESS;
635 	}
636 	v = isc_mem_cget(diff->mctx, length, sizeof(dns_difftuple_t *));
637 	for (i = 0; i < length; i++) {
638 		p = ISC_LIST_HEAD(diff->tuples);
639 		v[i] = p;
640 		ISC_LIST_UNLINK(diff->tuples, p, link);
641 	}
642 	INSIST(ISC_LIST_HEAD(diff->tuples) == NULL);
643 	qsort(v, length, sizeof(v[0]), compare);
644 	for (i = 0; i < length; i++) {
645 		ISC_LIST_APPEND(diff->tuples, v[i], link);
646 	}
647 	isc_mem_cput(diff->mctx, v, length, sizeof(dns_difftuple_t *));
648 	return ISC_R_SUCCESS;
649 }
650 
651 /*
652  * Create an rdataset containing the single RR of the given
653  * tuple.  The caller must allocate the rdata, rdataset and
654  * an rdatalist structure for it to refer to.
655  */
656 
657 static void
658 diff_tuple_tordataset(dns_difftuple_t *t, dns_rdata_t *rdata,
659 		      dns_rdatalist_t *rdl, dns_rdataset_t *rds) {
660 	REQUIRE(DNS_DIFFTUPLE_VALID(t));
661 	REQUIRE(rdl != NULL);
662 	REQUIRE(rds != NULL);
663 
664 	dns_rdatalist_init(rdl);
665 	rdl->type = t->rdata.type;
666 	rdl->rdclass = t->rdata.rdclass;
667 	rdl->ttl = t->ttl;
668 	dns_rdataset_init(rds);
669 	ISC_LINK_INIT(rdata, link);
670 	dns_rdata_clone(&t->rdata, rdata);
671 	ISC_LIST_APPEND(rdl->rdata, rdata, link);
672 	dns_rdatalist_tordataset(rdl, rds);
673 }
674 
675 isc_result_t
676 dns_diff_print(const dns_diff_t *diff, FILE *file) {
677 	isc_result_t result;
678 	dns_difftuple_t *t;
679 	char *mem = NULL;
680 	unsigned int size = 2048;
681 	const char *op = NULL;
682 
683 	REQUIRE(DNS_DIFF_VALID(diff));
684 
685 	mem = isc_mem_get(diff->mctx, size);
686 
687 	for (t = ISC_LIST_HEAD(diff->tuples); t != NULL;
688 	     t = ISC_LIST_NEXT(t, link))
689 	{
690 		isc_buffer_t buf;
691 		isc_region_t r;
692 
693 		dns_rdatalist_t rdl;
694 		dns_rdataset_t rds;
695 		dns_rdata_t rd = DNS_RDATA_INIT;
696 
697 		diff_tuple_tordataset(t, &rd, &rdl, &rds);
698 	again:
699 		isc_buffer_init(&buf, mem, size);
700 		result = dns_rdataset_totext(&rds, &t->name, false, false,
701 					     &buf);
702 
703 		if (result == ISC_R_NOSPACE) {
704 			isc_mem_put(diff->mctx, mem, size);
705 			size += 1024;
706 			mem = isc_mem_get(diff->mctx, size);
707 			goto again;
708 		}
709 
710 		if (result != ISC_R_SUCCESS) {
711 			goto cleanup;
712 		}
713 		/*
714 		 * Get rid of final newline.
715 		 */
716 		INSIST(buf.used >= 1 &&
717 		       ((char *)buf.base)[buf.used - 1] == '\n');
718 		buf.used--;
719 
720 		isc_buffer_usedregion(&buf, &r);
721 		switch (t->op) {
722 		case DNS_DIFFOP_EXISTS:
723 			op = "exists";
724 			break;
725 		case DNS_DIFFOP_ADD:
726 			op = "add";
727 			break;
728 		case DNS_DIFFOP_DEL:
729 			op = "del";
730 			break;
731 		case DNS_DIFFOP_ADDRESIGN:
732 			op = "add re-sign";
733 			break;
734 		case DNS_DIFFOP_DELRESIGN:
735 			op = "del re-sign";
736 			break;
737 		}
738 		if (file != NULL) {
739 			fprintf(file, "%s %.*s\n", op, (int)r.length,
740 				(char *)r.base);
741 		} else {
742 			isc_log_write(DIFF_COMMON_LOGARGS, ISC_LOG_DEBUG(7),
743 				      "%s %.*s", op, (int)r.length,
744 				      (char *)r.base);
745 		}
746 	}
747 	result = ISC_R_SUCCESS;
748 cleanup:
749 	if (mem != NULL) {
750 		isc_mem_put(diff->mctx, mem, size);
751 	}
752 	return result;
753 }
754