contrib/bind9/lib/dns/rpz.c

   1 /*
   2  * Copyright (C) 2011, 2012  Internet Systems Consortium, Inc. ("ISC")
   3  *
   4  * Permission to use, copy, modify, and/or distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
   9  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  10  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  11  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  12  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  13  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  14  * PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 /* $Id$ */
  18
  19 /*! \file */
  20
  21 #include <config.h>
  22
  23 #include <isc/buffer.h>
  24 #include <isc/mem.h>
  25 #include <isc/net.h>
  26 #include <isc/netaddr.h>
  27 #include <isc/print.h>
  28 #include <isc/stdlib.h>
  29 #include <isc/string.h>
  30 #include <isc/util.h>
  31
  32 #include <dns/db.h>
  33 #include <dns/fixedname.h>
  34 #include <dns/log.h>
  35 #include <dns/rdata.h>
  36 #include <dns/rdataset.h>
  37 #include <dns/rdatastruct.h>
  38 #include <dns/result.h>
  39 #include <dns/rpz.h>
  40 #include <dns/view.h>
  41
  42
  43 /*
  44  * Parallel radix trees for databases of response policy IP addresses
  45  *
  46  * The radix or Patricia trees are somewhat specialized to handle response
  47  * policy addresses by representing the two test of IP IP addresses and name
  48  * server IP addresses in a single tree.
  49  *
  50  * Each leaf indicates that an IP address is listed in the IP address or the
  51  * name server IP address policy sub-zone (or both) of the corresponding
  52  * response response zone.  The policy data such as a CNAME or an A record
  53  * is kept in the policy zone.  After an IP address has been found in a radix
  54  * tree, the node in the policy zone's database is found by converting
  55  * the IP address to a domain name in a canonical form.
  56  *
  57  * The response policy zone canonical form of IPv6 addresses is one of:
  58  *      prefix.W.W.W.W.W.W.W.W
  59  *      prefix.WORDS.zz
  60  *      prefix.WORDS.zz.WORDS
  61  *      prefix.zz.WORDS
  62  *  where
  63  *      prefix  is the prefix length of the IPv6 address between 1 and 128
  64  *      W       is a number between 0 and 65535
  65  *      WORDS   is one or more numbers W separated with "."
  66  *      zz      corresponds to :: in the standard IPv6 text representation
  67  *
  68  * The canonical form of IPv4 addresses is:
  69  *      prefix.B.B.B.B
  70  *  where
  71  *      prefix  is the prefix length of the address between 1 and 32
  72  *      B       is a number between 0 and 255
  73  *
  74  * IPv4 addresses are distinguished from IPv6 addresses by having
  75  * 5 labels all of which are numbers, and a prefix between 1 and 32.
  76  */
  77
  78
  79 /*
  80  * Use a private definition of IPv6 addresses because s6_addr32 is not
  81  * always defined and our IPv6 addresses are in non-standard byte order
  82  */
  83 typedef isc_uint32_t            dns_rpz_cidr_word_t;
  84 #define DNS_RPZ_CIDR_WORD_BITS  ((int)sizeof(dns_rpz_cidr_word_t)*8)
  85 #define DNS_RPZ_CIDR_KEY_BITS   ((int)sizeof(dns_rpz_cidr_key_t)*8)
  86 #define DNS_RPZ_CIDR_WORDS      (128/DNS_RPZ_CIDR_WORD_BITS)
  87 typedef struct {
  88         dns_rpz_cidr_word_t     w[DNS_RPZ_CIDR_WORDS];
  89 } dns_rpz_cidr_key_t;
  90
  91 #define ADDR_V4MAPPED           0xffff
  92
  93 #define DNS_RPZ_WORD_MASK(b)                            \
  94         ((b) == 0 ? (dns_rpz_cidr_word_t)(-1)           \
  95                   : ((dns_rpz_cidr_word_t)(-1)          \
  96                     << (DNS_RPZ_CIDR_WORD_BITS - (b))))
  97
  98 #define DNS_RPZ_IP_BIT(ip, bitno) \
  99         (1 & ((ip)->w[(bitno)/DNS_RPZ_CIDR_WORD_BITS] >> \
 100             (DNS_RPZ_CIDR_WORD_BITS - 1 - ((bitno) % DNS_RPZ_CIDR_WORD_BITS))))
 101
 102 typedef struct dns_rpz_cidr_node        dns_rpz_cidr_node_t;
 103 typedef isc_uint8_t                     dns_rpz_cidr_flags_t;
 104 struct dns_rpz_cidr_node {
 105         dns_rpz_cidr_node_t             *parent;
 106         dns_rpz_cidr_node_t             *child[2];
 107         dns_rpz_cidr_key_t              ip;
 108         dns_rpz_cidr_bits_t             bits;
 109         dns_rpz_cidr_flags_t            flags;
 110 #define DNS_RPZ_CIDR_FG_IP       0x01   /* has IP data or is parent of IP */
 111 #define DNS_RPZ_CIDR_FG_IP_DATA  0x02   /* has IP data */
 112 #define DNS_RPZ_CIDR_FG_NSIPv4   0x04   /* has or is parent of NSIPv4 data */
 113 #define DNS_RPZ_CIDR_FG_NSIPv6   0x08   /* has or is parent of NSIPv6 data */
 114 #define DNS_RPZ_CIDR_FG_NSIP_DATA 0x10  /* has NSIP data */
 115 };
 116
 117 struct dns_rpz_cidr {
 118         isc_mem_t               *mctx;
 119         isc_boolean_t           have_nsdname;   /* zone has NSDNAME record */
 120         dns_rpz_cidr_node_t     *root;
 121         dns_name_t              ip_name;        /* RPZ_IP_ZONE.LOCALHOST. */
 122         dns_name_t              nsip_name;      /* RPZ_NSIP_ZONE.LOCALHOST. */
 123         dns_name_t              nsdname_name;   /* RPZ_NSDNAME_ZONE.LOCALHOST */
 124 };
 125
 126 static isc_boolean_t            have_rpz_zones = ISC_FALSE;
 127
 128 const char *
 129 dns_rpz_type2str(dns_rpz_type_t type) {
 130         switch (type) {
 131         case DNS_RPZ_TYPE_QNAME:
 132                 return ("QNAME");
 133         case DNS_RPZ_TYPE_IP:
 134                 return ("IP");
 135         case DNS_RPZ_TYPE_NSIP:
 136                 return ("NSIP");
 137         case DNS_RPZ_TYPE_NSDNAME:
 138                 return ("NSDNAME");
 139         case DNS_RPZ_TYPE_BAD:
 140                 break;
 141         }
 142         FATAL_ERROR(__FILE__, __LINE__,
 143                     "impossible rpz type %d", type);
 144         return ("impossible");
 145 }
 146
 147 dns_rpz_policy_t
 148 dns_rpz_str2policy(const char *str) {
 149         if (str == NULL)
 150                 return (DNS_RPZ_POLICY_ERROR);
 151         if (!strcasecmp(str, "given"))
 152                 return (DNS_RPZ_POLICY_GIVEN);
 153         if (!strcasecmp(str, "disabled"))
 154                 return (DNS_RPZ_POLICY_DISABLED);
 155         if (!strcasecmp(str, "passthru"))
 156                 return (DNS_RPZ_POLICY_PASSTHRU);
 157         if (!strcasecmp(str, "nxdomain"))
 158                 return (DNS_RPZ_POLICY_NXDOMAIN);
 159         if (!strcasecmp(str, "nodata"))
 160                 return (DNS_RPZ_POLICY_NODATA);
 161         if (!strcasecmp(str, "cname"))
 162                 return (DNS_RPZ_POLICY_CNAME);
 163         /*
 164          * Obsolete
 165          */
 166         if (!strcasecmp(str, "no-op"))
 167                 return (DNS_RPZ_POLICY_PASSTHRU);
 168         return (DNS_RPZ_POLICY_ERROR);
 169 }
 170
 171 const char *
 172 dns_rpz_policy2str(dns_rpz_policy_t policy) {
 173         const char *str;
 174
 175         switch (policy) {
 176         case DNS_RPZ_POLICY_PASSTHRU:
 177                 str = "PASSTHRU";
 178                 break;
 179         case DNS_RPZ_POLICY_NXDOMAIN:
 180                 str = "NXDOMAIN";
 181                 break;
 182         case DNS_RPZ_POLICY_NODATA:
 183                 str = "NODATA";
 184                 break;
 185         case DNS_RPZ_POLICY_RECORD:
 186                 str = "records";
 187                 break;
 188         case DNS_RPZ_POLICY_CNAME:
 189         case DNS_RPZ_POLICY_WILDCNAME:
 190                 str = "CNAME";
 191                 break;
 192         default:
 193                 str = "";
 194                 INSIST(0);
 195         }
 196         return (str);
 197 }
 198
 199 /*
 200  * Free the radix tree of a response policy database.
 201  */
 202 void
 203 dns_rpz_cidr_free(dns_rpz_cidr_t **cidrp) {
 204         dns_rpz_cidr_node_t *cur, *child, *parent;
 205         dns_rpz_cidr_t *cidr;
 206
 207         REQUIRE(cidrp != NULL);
 208
 209         cidr = *cidrp;
 210         if (cidr == NULL)
 211                 return;
 212
 213         cur = cidr->root;
 214         while (cur != NULL) {
 215                 /* Depth first. */
 216                 child = cur->child[0];
 217                 if (child != NULL) {
 218                         cur = child;
 219                         continue;
 220                 }
 221                 child = cur->child[1];
 222                 if (child != NULL) {
 223                         cur = child;
 224                         continue;
 225                 }
 226
 227                 /* Delete this leaf and go up. */
 228                 parent = cur->parent;
 229                 if (parent == NULL)
 230                         cidr->root = NULL;
 231                 else
 232                         parent->child[parent->child[1] == cur] = NULL;
 233                 isc_mem_put(cidr->mctx, cur, sizeof(*cur));
 234                 cur = parent;
 235         }
 236
 237         dns_name_free(&cidr->ip_name, cidr->mctx);
 238         dns_name_free(&cidr->nsip_name, cidr->mctx);
 239         dns_name_free(&cidr->nsdname_name, cidr->mctx);
 240         isc_mem_put(cidr->mctx, cidr, sizeof(*cidr));
 241         *cidrp = NULL;
 242 }
 243
 244 /*
 245  * Forget a view's list of policy zones.
 246  */
 247 void
 248 dns_rpz_view_destroy(dns_view_t *view) {
 249         dns_rpz_zone_t *zone;
 250
 251         REQUIRE(view != NULL);
 252
 253         while (!ISC_LIST_EMPTY(view->rpz_zones)) {
 254                 zone = ISC_LIST_HEAD(view->rpz_zones);
 255                 ISC_LIST_UNLINK(view->rpz_zones, zone, link);
 256                 if (dns_name_dynamic(&zone->origin))
 257                         dns_name_free(&zone->origin, view->mctx);
 258                 if (dns_name_dynamic(&zone->nsdname))
 259                         dns_name_free(&zone->nsdname, view->mctx);
 260                 if (dns_name_dynamic(&zone->cname))
 261                         dns_name_free(&zone->cname, view->mctx);
 262                 isc_mem_put(view->mctx, zone, sizeof(*zone));
 263         }
 264 }
 265
 266 /*
 267  * Note that we have at least one response policy zone.
 268  * It would be better for something to tell the rbtdb code that the
 269  * zone is in at least one view's list of policy zones.
 270  */
 271 void
 272 dns_rpz_set_need(isc_boolean_t need) {
 273         have_rpz_zones = need;
 274 }
 275
 276 isc_boolean_t
 277 dns_rpz_needed(void) {
 278         return (have_rpz_zones);
 279 }
 280
 281 /*
 282  * Start a new radix tree for a response policy zone.
 283  */
 284 isc_result_t
 285 dns_rpz_new_cidr(isc_mem_t *mctx, dns_name_t *origin,
 286                  dns_rpz_cidr_t **rbtdb_cidr)
 287 {
 288         isc_result_t result;
 289         dns_rpz_cidr_t *cidr;
 290
 291         REQUIRE(rbtdb_cidr != NULL && *rbtdb_cidr == NULL);
 292
 293         /*
 294          * Only if there is at least one response policy zone.
 295          */
 296         if (!have_rpz_zones)
 297                 return (ISC_R_SUCCESS);
 298
 299         cidr = isc_mem_get(mctx, sizeof(*cidr));
 300         if (cidr == NULL)
 301                 return (ISC_R_NOMEMORY);
 302         memset(cidr, 0, sizeof(*cidr));
 303         cidr->mctx = mctx;
 304
 305         dns_name_init(&cidr->ip_name, NULL);
 306         result = dns_name_fromstring2(&cidr->ip_name, DNS_RPZ_IP_ZONE, origin,
 307                                       DNS_NAME_DOWNCASE, mctx);
 308         if (result != ISC_R_SUCCESS) {
 309                 isc_mem_put(mctx, cidr, sizeof(*cidr));
 310                 return (result);
 311         }
 312
 313         dns_name_init(&cidr->nsip_name, NULL);
 314         result = dns_name_fromstring2(&cidr->nsip_name, DNS_RPZ_NSIP_ZONE,
 315                                       origin, DNS_NAME_DOWNCASE, mctx);
 316         if (result != ISC_R_SUCCESS) {
 317                 dns_name_free(&cidr->ip_name, mctx);
 318                 isc_mem_put(mctx, cidr, sizeof(*cidr));
 319                 return (result);
 320         }
 321
 322         dns_name_init(&cidr->nsdname_name, NULL);
 323         result = dns_name_fromstring2(&cidr->nsdname_name, DNS_RPZ_NSDNAME_ZONE,
 324                                       origin, DNS_NAME_DOWNCASE, mctx);
 325         if (result != ISC_R_SUCCESS) {
 326                 dns_name_free(&cidr->nsip_name, mctx);
 327                 dns_name_free(&cidr->ip_name, mctx);
 328                 isc_mem_put(mctx, cidr, sizeof(*cidr));
 329                 return (result);
 330         }
 331
 332         *rbtdb_cidr = cidr;
 333         return (ISC_R_SUCCESS);
 334 }
 335
 336 /*
 337  * See if a policy zone has IP, NSIP, or NSDNAME rules or records.
 338  */
 339 void
 340 dns_rpz_enabled(dns_rpz_cidr_t *cidr, dns_rpz_st_t *st) {
 341         if (cidr == NULL)
 342                 return;
 343         if (cidr->root != NULL &&
 344             (cidr->root->flags & DNS_RPZ_CIDR_FG_IP) != 0)
 345                 st->state |= DNS_RPZ_HAVE_IP;
 346         if (cidr->root != NULL &&
 347             (cidr->root->flags & DNS_RPZ_CIDR_FG_NSIPv4) != 0)
 348                 st->state |= DNS_RPZ_HAVE_NSIPv4;
 349         if (cidr->root != NULL &&
 350             (cidr->root->flags & DNS_RPZ_CIDR_FG_NSIPv6) != 0)
 351                 st->state |= DNS_RPZ_HAVE_NSIPv6;
 352         if (cidr->have_nsdname)
 353                 st->state |= DNS_RPZ_HAVE_NSDNAME;
 354 }
 355
 356 static inline dns_rpz_cidr_flags_t
 357 get_flags(const dns_rpz_cidr_key_t *ip, dns_rpz_cidr_bits_t prefix,
 358         dns_rpz_type_t rpz_type)
 359 {
 360         if (rpz_type == DNS_RPZ_TYPE_NSIP) {
 361                 if (prefix >= 96 &&
 362                     ip->w[0] == 0 && ip->w[1] == 0 &&
 363                     ip->w[2] == ADDR_V4MAPPED)
 364                         return (DNS_RPZ_CIDR_FG_NSIP_DATA |
 365                                 DNS_RPZ_CIDR_FG_NSIPv4);
 366                 else
 367                         return (DNS_RPZ_CIDR_FG_NSIP_DATA |
 368                                 DNS_RPZ_CIDR_FG_NSIPv6);
 369         } else {
 370                 return (DNS_RPZ_CIDR_FG_IP | DNS_RPZ_CIDR_FG_IP_DATA);
 371         }
 372 }
 373
 374 /*
 375  * Mark a node as having IP or NSIP data and all of its parents
 376  * as members of the IP or NSIP tree.
 377  */
 378 static void
 379 set_node_flags(dns_rpz_cidr_node_t *node, dns_rpz_type_t rpz_type) {
 380         dns_rpz_cidr_flags_t flags;
 381
 382         flags = get_flags(&node->ip, node->bits, rpz_type);
 383         node->flags |= flags;
 384         flags &= ~(DNS_RPZ_CIDR_FG_NSIP_DATA | DNS_RPZ_CIDR_FG_IP_DATA);
 385         for (;;) {
 386                 node = node->parent;
 387                 if (node == NULL)
 388                         return;
 389                 node->flags |= flags;
 390         }
 391 }
 392
 393 /*
 394  * Make a radix tree node.
 395  */
 396 static dns_rpz_cidr_node_t *
 397 new_node(dns_rpz_cidr_t *cidr, const dns_rpz_cidr_key_t *ip,
 398          dns_rpz_cidr_bits_t bits, dns_rpz_cidr_flags_t flags)
 399 {
 400         dns_rpz_cidr_node_t *node;
 401         int i, words, wlen;
 402
 403         node = isc_mem_get(cidr->mctx, sizeof(*node));
 404         if (node == NULL)
 405                 return (NULL);
 406         memset(node, 0, sizeof(*node));
 407
 408         node->flags = flags & ~(DNS_RPZ_CIDR_FG_IP_DATA |
 409                                 DNS_RPZ_CIDR_FG_NSIP_DATA);
 410
 411         node->bits = bits;
 412         words = bits / DNS_RPZ_CIDR_WORD_BITS;
 413         wlen = bits % DNS_RPZ_CIDR_WORD_BITS;
 414         i = 0;
 415         while (i < words) {
 416                 node->ip.w[i] = ip->w[i];
 417                 ++i;
 418         }
 419         if (wlen != 0) {
 420                 node->ip.w[i] = ip->w[i] & DNS_RPZ_WORD_MASK(wlen);
 421                 ++i;
 422         }
 423         while (i < DNS_RPZ_CIDR_WORDS)
 424                 node->ip.w[i++] = 0;
 425
 426         return (node);
 427 }
 428
 429 static void
 430 badname(int level, dns_name_t *name, const char *comment) {
 431         char printname[DNS_NAME_FORMATSIZE];
 432
 433         if (isc_log_wouldlog(dns_lctx, level)) {
 434                 dns_name_format(name, printname, sizeof(printname));
 435                 isc_log_write(dns_lctx, DNS_LOGCATEGORY_RPZ,
 436                               DNS_LOGMODULE_RBTDB, level,
 437                               "invalid rpz \"%s\"%s", printname, comment);
 438         }
 439 }
 440
 441 /*
 442  * Convert an IP address from radix tree binary (host byte order) to
 443  * to its canonical response policy domain name and its name in the
 444  * policy zone.
 445  */
 446 static isc_result_t
 447 ip2name(dns_rpz_cidr_t *cidr, const dns_rpz_cidr_key_t *tgt_ip,
 448         dns_rpz_cidr_bits_t tgt_prefix, dns_rpz_type_t type,
 449         dns_name_t *canon_name, dns_name_t *search_name)
 450 {
 451 #ifndef INET6_ADDRSTRLEN
 452 #define INET6_ADDRSTRLEN 46
 453 #endif
 454         int w[DNS_RPZ_CIDR_WORDS*2];
 455         char str[1+8+1+INET6_ADDRSTRLEN+1];
 456         isc_buffer_t buffer;
 457         dns_name_t *name;
 458         isc_result_t result;
 459         isc_boolean_t zeros;
 460         int i, n, len;
 461
 462         if (tgt_prefix > 96 &&
 463             tgt_ip->w[0] == 0 &&
 464             tgt_ip->w[1] == 0 &&
 465             tgt_ip->w[2] == ADDR_V4MAPPED) {
 466                 len = snprintf(str, sizeof(str), "%d.%d.%d.%d.%d",
 467                                tgt_prefix - 96,
 468                                tgt_ip->w[3] & 0xff,
 469                                (tgt_ip->w[3]>>8) & 0xff,
 470                                (tgt_ip->w[3]>>16) & 0xff,
 471                                (tgt_ip->w[3]>>24) & 0xff);
 472                 if (len == -1 || len > (int)sizeof(str))
 473                         return (ISC_R_FAILURE);
 474         } else {
 475                 for (i = 0; i < DNS_RPZ_CIDR_WORDS; i++) {
 476                         w[i*2+1] = ((tgt_ip->w[DNS_RPZ_CIDR_WORDS-1-i] >> 16)
 477                                     & 0xffff);
 478                         w[i*2] = tgt_ip->w[DNS_RPZ_CIDR_WORDS-1-i] & 0xffff;
 479                 }
 480                 zeros = ISC_FALSE;
 481                 len = snprintf(str, sizeof(str), "%d", tgt_prefix);
 482                 if (len == -1)
 483                         return (ISC_R_FAILURE);
 484                 i = 0;
 485                 while (i < DNS_RPZ_CIDR_WORDS * 2) {
 486                         if (w[i] != 0 || zeros
 487                             || i >= DNS_RPZ_CIDR_WORDS * 2 - 1
 488                             || w[i+1] != 0) {
 489                                 INSIST((size_t)len <= sizeof(str));
 490                                 n = snprintf(&str[len], sizeof(str) - len,
 491                                              ".%x", w[i++]);
 492                                 if (n < 0)
 493                                         return (ISC_R_FAILURE);
 494                                 len += n;
 495                         } else {
 496                                 zeros = ISC_TRUE;
 497                                 INSIST((size_t)len <= sizeof(str));
 498                                 n = snprintf(&str[len], sizeof(str) - len,
 499                                              ".zz");
 500                                 if (n < 0)
 501                                         return (ISC_R_FAILURE);
 502                                 len += n;
 503                                 i += 2;
 504                                 while (i < DNS_RPZ_CIDR_WORDS * 2 && w[i] == 0)
 505                                         ++i;
 506                         }
 507                         if (len > (int)sizeof(str))
 508                                 return (ISC_R_FAILURE);
 509                 }
 510         }
 511
 512         if (canon_name != NULL) {
 513                 isc__buffer_init(&buffer, str, sizeof(str));
 514                 isc__buffer_add(&buffer, len);
 515                 result = dns_name_fromtext(canon_name, &buffer,
 516                                            dns_rootname, 0, NULL);
 517                 if (result != ISC_R_SUCCESS)
 518                         return (result);
 519         }
 520         if (search_name != NULL) {
 521                 isc__buffer_init(&buffer, str, sizeof(str));
 522                 isc__buffer_add(&buffer, len);
 523                 if (type == DNS_RPZ_TYPE_NSIP)
 524                         name = &cidr->nsip_name;
 525                 else
 526                         name = &cidr->ip_name;
 527                 result = dns_name_fromtext(search_name, &buffer, name, 0, NULL);
 528                 if (result != ISC_R_SUCCESS)
 529                         return (result);
 530         }
 531         return (ISC_R_SUCCESS);
 532 }
 533
 534 /*
 535  * Decide which kind of IP address response policy zone a name is in.
 536  */
 537 static dns_rpz_type_t
 538 set_type(dns_rpz_cidr_t *cidr, dns_name_t *name) {
 539
 540         if (dns_name_issubdomain(name, &cidr->ip_name))
 541                 return (DNS_RPZ_TYPE_IP);
 542
 543         /*
 544          * Require `./configure --enable-rpz-nsip` and nsdname
 545          * until consistency problems are resolved.
 546          */
 547 #ifdef ENABLE_RPZ_NSIP
 548         if (dns_name_issubdomain(name, &cidr->nsip_name))
 549                 return (DNS_RPZ_TYPE_NSIP);
 550 #endif
 551
 552 #ifdef ENABLE_RPZ_NSDNAME
 553         if (dns_name_issubdomain(name, &cidr->nsdname_name))
 554                 return (DNS_RPZ_TYPE_NSDNAME);
 555 #endif
 556
 557         return (DNS_RPZ_TYPE_QNAME);
 558 }
 559
 560 /*
 561  * Convert an IP address from canonical response policy domain name form
 562  * to radix tree binary (host byte order).
 563  */
 564 static isc_result_t
 565 name2ipkey(dns_rpz_cidr_t *cidr, int level, dns_name_t *src_name,
 566            dns_rpz_type_t type, dns_rpz_cidr_key_t *tgt_ip,
 567            dns_rpz_cidr_bits_t *tgt_prefix)
 568 {
 569         isc_buffer_t buffer;
 570         unsigned char data[DNS_NAME_MAXWIRE+1];
 571         dns_fixedname_t fname;
 572         dns_name_t *name;
 573         const char *cp, *end;
 574         char *cp2;
 575         int ip_labels;
 576         dns_rpz_cidr_bits_t bits;
 577         unsigned long prefix, l;
 578         int i;
 579
 580         /*
 581          * Need at least enough labels for the shortest name,
 582          * :: or 128.*.RPZ_x_ZONE.rpz.LOCALHOST.
 583          */
 584         ip_labels = dns_name_countlabels(src_name);
 585         ip_labels -= dns_name_countlabels(&cidr->ip_name);
 586         ip_labels--;
 587         if (ip_labels < 1) {
 588                 badname(level, src_name, ", too short");
 589                 return (ISC_R_FAILURE);
 590         }
 591
 592         /*
 593          * Get text for the IP address without RPZ_x_ZONE.rpz.LOCALHOST.
 594          */
 595         dns_fixedname_init(&fname);
 596         name = dns_fixedname_name(&fname);
 597         dns_name_split(src_name, dns_name_countlabels(&cidr->ip_name),
 598                        name, NULL);
 599         isc_buffer_init(&buffer, data, sizeof(data));
 600         dns_name_totext(name, ISC_TRUE, &buffer);
 601         isc_buffer_putuint8(&buffer, '\0');
 602         cp = isc_buffer_base(&buffer);
 603
 604         prefix = strtoul(cp, &cp2, 10);
 605         if (prefix < 1U || prefix > 128U || *cp2 != '.') {
 606                 badname(level, src_name, ", bad prefix length");
 607                 return (ISC_R_FAILURE);
 608         }
 609         cp = cp2+1;
 610
 611         end = isc_buffer_used(&buffer);
 612         if (ip_labels == 4 && !strchr(cp, 'z')) {
 613                 /*
 614                  * Convert an IPv4 address
 615                  * from the form "prefix.w.z.y.x"
 616                  */
 617                 if (prefix > 32U) {
 618                         badname(level, src_name, "; bad IPv4 prefix length");
 619                         return (ISC_R_FAILURE);
 620                 }
 621                 prefix += 96;
 622                 *tgt_prefix = (dns_rpz_cidr_bits_t)prefix;
 623                 tgt_ip->w[0] = 0;
 624                 tgt_ip->w[1] = 0;
 625                 tgt_ip->w[2] = ADDR_V4MAPPED;
 626                 tgt_ip->w[3] = 0;
 627                 for (i = 0; i < 32; i += 8) {
 628                         l = strtoul(cp, &cp2, 10);
 629                         if (l > 255U || (*cp2 != '.' && *cp2 != '\0')) {
 630                                 badname(level, src_name, "; bad IPv4 address");
 631                                 return (ISC_R_FAILURE);
 632                         }
 633                         tgt_ip->w[3] |= l << i;
 634                         cp = cp2 + 1;
 635                 }
 636         } else {
 637                 /*
 638                  * Convert a text IPv6 address.
 639                  */
 640                 *tgt_prefix = (dns_rpz_cidr_bits_t)prefix;
 641                 for (i = 0;
 642                      ip_labels > 0 && i < DNS_RPZ_CIDR_WORDS * 2;
 643                      ip_labels--) {
 644                         if (cp[0] == 'z' && cp[1] == 'z' &&
 645                             (cp[2] == '.' || cp[2] == '\0') &&
 646                             i <= 6) {
 647                                 do {
 648                                         if ((i & 1) == 0)
 649                                             tgt_ip->w[3-i/2] = 0;
 650                                         ++i;
 651                                 } while (ip_labels + i <= 8);
 652                                 cp += 3;
 653                         } else {
 654                                 l = strtoul(cp, &cp2, 16);
 655                                 if (l > 0xffffu ||
 656                                     (*cp2 != '.' && *cp2 != '\0')) {
 657                                         badname(level, src_name, "");
 658                                         return (ISC_R_FAILURE);
 659                                 }
 660                                 if ((i & 1) == 0)
 661                                         tgt_ip->w[3-i/2] = l;
 662                                 else
 663                                         tgt_ip->w[3-i/2] |= l << 16;
 664                                 i++;
 665                                 cp = cp2 + 1;
 666                         }
 667                 }
 668         }
 669         if (cp != end) {
 670                 badname(level, src_name, "");
 671                 return (ISC_R_FAILURE);
 672         }
 673
 674         /*
 675          * Check for 1s after the prefix length.
 676          */
 677         bits = (dns_rpz_cidr_bits_t)prefix;
 678         while (bits < DNS_RPZ_CIDR_KEY_BITS) {
 679                 dns_rpz_cidr_word_t aword;
 680
 681                 i = bits % DNS_RPZ_CIDR_WORD_BITS;
 682                 aword = tgt_ip->w[bits / DNS_RPZ_CIDR_WORD_BITS];
 683                 if ((aword & ~DNS_RPZ_WORD_MASK(i)) != 0) {
 684                         badname(level, src_name, "; wrong prefix length");
 685                         return (ISC_R_FAILURE);
 686                 }
 687                 bits -= i;
 688                 bits += DNS_RPZ_CIDR_WORD_BITS;
 689         }
 690
 691         /*
 692          * Convert the IPv6 address back to a canonical policy domain name
 693          * to ensure that it is in canonical form.
 694          */
 695         if (ISC_R_SUCCESS != ip2name(cidr, tgt_ip, (dns_rpz_cidr_bits_t)prefix,
 696                                      type, NULL, name) ||
 697             !dns_name_equal(src_name, name)) {
 698                 badname(level, src_name, "; not canonical");
 699                 return (ISC_R_FAILURE);
 700         }
 701
 702         return (ISC_R_SUCCESS);
 703 }
 704
 705 /*
 706  * Find first differing bit.
 707  */
 708 static int
 709 ffbit(dns_rpz_cidr_word_t w) {
 710         int bit;
 711
 712         bit = DNS_RPZ_CIDR_WORD_BITS-1;
 713         if ((w & 0xffff0000) != 0) {
 714                 w >>= 16;
 715                 bit -= 16;
 716         }
 717         if ((w & 0xff00) != 0) {
 718                 w >>= 8;
 719                 bit -= 8;
 720         }
 721         if ((w & 0xf0) != 0) {
 722                 w >>= 4;
 723                 bit -= 4;
 724         }
 725         if ((w & 0xc) != 0) {
 726                 w >>= 2;
 727                 bit -= 2;
 728         }
 729         if ((w & 2) != 0)
 730                 --bit;
 731         return (bit);
 732 }
 733
 734 /*
 735  * Find the first differing bit in two keys.
 736  */
 737 static int
 738 diff_keys(const dns_rpz_cidr_key_t *key1, dns_rpz_cidr_bits_t bits1,
 739           const dns_rpz_cidr_key_t *key2, dns_rpz_cidr_bits_t bits2)
 740 {
 741         dns_rpz_cidr_word_t delta;
 742         dns_rpz_cidr_bits_t maxbit, bit;
 743         int i;
 744
 745         maxbit = ISC_MIN(bits1, bits2);
 746
 747         /*
 748          * find the first differing words
 749          */
 750         for (i = 0, bit = 0;
 751              bit <= maxbit;
 752              i++, bit += DNS_RPZ_CIDR_WORD_BITS) {
 753                 delta = key1->w[i] ^ key2->w[i];
 754                 if (delta != 0) {
 755                         bit += ffbit(delta);
 756                         break;
 757                 }
 758         }
 759         return (ISC_MIN(bit, maxbit));
 760 }
 761
 762 /*
 763  * Search a radix tree for an IP address for ordinary lookup
 764  *      or for a CIDR block adding or deleting an entry
 765  * The tree read (for simple search) or write lock must be held by the caller.
 766  *
 767  * Return ISC_R_SUCCESS, ISC_R_NOTFOUND, DNS_R_PARTIALMATCH, ISC_R_EXISTS,
 768  *      ISC_R_NOMEMORY
 769  */
 770 static isc_result_t
 771 search(dns_rpz_cidr_t *cidr, const dns_rpz_cidr_key_t *tgt_ip,
 772        dns_rpz_cidr_bits_t tgt_prefix, dns_rpz_type_t type,
 773        isc_boolean_t create,
 774        dns_rpz_cidr_node_t **found)             /* NULL or longest match node */
 775 {
 776         dns_rpz_cidr_node_t *cur, *parent, *child, *new_parent, *sibling;
 777         int cur_num, child_num;
 778         dns_rpz_cidr_bits_t dbit;
 779         dns_rpz_cidr_flags_t flags, data_flag;
 780         isc_result_t find_result;
 781
 782         flags = get_flags(tgt_ip, tgt_prefix, type);
 783         data_flag = flags & (DNS_RPZ_CIDR_FG_IP_DATA |
 784                              DNS_RPZ_CIDR_FG_NSIP_DATA);
 785
 786         find_result = ISC_R_NOTFOUND;
 787         if (found != NULL)
 788                 *found = NULL;
 789         cur = cidr->root;
 790         parent = NULL;
 791         cur_num = 0;
 792         for (;;) {
 793                 if (cur == NULL) {
 794                         /*
 795                          * No child so we cannot go down.  Fail or
 796                          * add the target as a child of the current parent.
 797                          */
 798                         if (!create)
 799                                 return (find_result);
 800                         child = new_node(cidr, tgt_ip, tgt_prefix, 0);
 801                         if (child == NULL)
 802                                 return (ISC_R_NOMEMORY);
 803                         if (parent == NULL)
 804                                 cidr->root = child;
 805                         else
 806                                 parent->child[cur_num] = child;
 807                         child->parent = parent;
 808                         set_node_flags(child, type);
 809                         if (found != NULL)
 810                                 *found = cur;
 811                         return (ISC_R_SUCCESS);
 812                 }
 813
 814                 /*
 815                  * Pretend a node not in the correct tree does not exist
 816                  * if we are not adding to the tree,
 817                  * If we are adding, then continue down to eventually
 818                  * add a node and mark/put this node in the correct tree.
 819                  */
 820                 if ((cur->flags & flags) == 0 && !create)
 821                         return (find_result);
 822
 823                 dbit = diff_keys(tgt_ip, tgt_prefix, &cur->ip, cur->bits);
 824                 /*
 825                  * dbit <= tgt_prefix and dbit <= cur->bits always.
 826                  * We are finished searching if we matched all of the target.
 827                  */
 828                 if (dbit == tgt_prefix) {
 829                         if (tgt_prefix == cur->bits) {
 830                                 /*
 831                                  * The current node matches the target exactly.
 832                                  * It is the answer if it has data.
 833                                  */
 834                                 if ((cur->flags & data_flag) != 0) {
 835                                         if (create)
 836                                                 return (ISC_R_EXISTS);
 837                                         if (found != NULL)
 838                                                 *found = cur;
 839                                         return (ISC_R_SUCCESS);
 840                                 } else if (create) {
 841                                         /*
 842                                          * The node had no data but does now.
 843                                          */
 844                                         set_node_flags(cur, type);
 845                                         if (found != NULL)
 846                                                 *found = cur;
 847                                         return (ISC_R_SUCCESS);
 848                                 }
 849                                 return (find_result);
 850                         }
 851
 852                         /*
 853                          * We know tgt_prefix < cur_bits which means that
 854                          * the target is shorter than the current node.
 855                          * Add the target as the current node's parent.
 856                          */
 857                         if (!create)
 858                                 return (find_result);
 859
 860                         new_parent = new_node(cidr, tgt_ip, tgt_prefix,
 861                                               cur->flags);
 862                         if (new_parent == NULL)
 863                                 return (ISC_R_NOMEMORY);
 864                         new_parent->parent = parent;
 865                         if (parent == NULL)
 866                                 cidr->root = new_parent;
 867                         else
 868                                 parent->child[cur_num] = new_parent;
 869                         child_num = DNS_RPZ_IP_BIT(&cur->ip, tgt_prefix+1);
 870                         new_parent->child[child_num] = cur;
 871                         cur->parent = new_parent;
 872                         set_node_flags(new_parent, type);
 873                         if (found != NULL)
 874                                 *found = new_parent;
 875                         return (ISC_R_SUCCESS);
 876                 }
 877
 878                 if (dbit == cur->bits) {
 879                         /*
 880                          * We have a partial match by matching of all of the
 881                          * current node but only part of the target.
 882                          * Try to go down.
 883                          */
 884                         if ((cur->flags & data_flag) != 0) {
 885                                 find_result = DNS_R_PARTIALMATCH;
 886                                 if (found != NULL)
 887                                         *found = cur;
 888                         }
 889
 890                         parent = cur;
 891                         cur_num = DNS_RPZ_IP_BIT(tgt_ip, dbit);
 892                         cur = cur->child[cur_num];
 893                         continue;
 894                 }
 895
 896
 897                 /*
 898                  * dbit < tgt_prefix and dbit < cur->bits,
 899                  * so we failed to match both the target and the current node.
 900                  * Insert a fork of a parent above the current node and
 901                  * add the target as a sibling of the current node
 902                  */
 903                 if (!create)
 904                         return (find_result);
 905
 906                 sibling = new_node(cidr, tgt_ip, tgt_prefix, 0);
 907                 if (sibling == NULL)
 908                         return (ISC_R_NOMEMORY);
 909                 new_parent = new_node(cidr, tgt_ip, dbit, cur->flags);
 910                 if (new_parent == NULL) {
 911                         isc_mem_put(cidr->mctx, sibling, sizeof(*sibling));
 912                         return (ISC_R_NOMEMORY);
 913                 }
 914                 new_parent->parent = parent;
 915                 if (parent == NULL)
 916                         cidr->root = new_parent;
 917                 else
 918                         parent->child[cur_num] = new_parent;
 919                 child_num = DNS_RPZ_IP_BIT(tgt_ip, dbit);
 920                 new_parent->child[child_num] = sibling;
 921                 new_parent->child[1-child_num] = cur;
 922                 cur->parent = new_parent;
 923                 sibling->parent = new_parent;
 924                 set_node_flags(sibling, type);
 925                 if (found != NULL)
 926                         *found = sibling;
 927                 return (ISC_R_SUCCESS);
 928         }
 929 }
 930
 931 /*
 932  * Add an IP address to the radix tree of a response policy database.
 933  *      The tree write lock must be held by the caller.
 934  */
 935 void
 936 dns_rpz_cidr_addip(dns_rpz_cidr_t *cidr, dns_name_t *name) {
 937         dns_rpz_cidr_key_t tgt_ip;
 938         dns_rpz_cidr_bits_t tgt_prefix;
 939         dns_rpz_type_t type;
 940
 941         if (cidr == NULL)
 942                 return;
 943
 944         /*
 945          * No worries if the new name is not an IP address.
 946          */
 947         type = set_type(cidr, name);
 948         switch (type) {
 949         case DNS_RPZ_TYPE_IP:
 950         case DNS_RPZ_TYPE_NSIP:
 951                 break;
 952         case DNS_RPZ_TYPE_NSDNAME:
 953                 cidr->have_nsdname = ISC_TRUE;
 954                 return;
 955         case DNS_RPZ_TYPE_QNAME:
 956         case DNS_RPZ_TYPE_BAD:
 957                 return;
 958         }
 959         if (ISC_R_SUCCESS != name2ipkey(cidr, DNS_RPZ_ERROR_LEVEL, name,
 960                                         type, &tgt_ip, &tgt_prefix))
 961                 return;
 962
 963         if (ISC_R_EXISTS == search(cidr, &tgt_ip, tgt_prefix, type,
 964                                    ISC_TRUE, NULL) &&
 965             isc_log_wouldlog(dns_lctx, DNS_RPZ_ERROR_LEVEL)) {
 966                 char printname[DNS_NAME_FORMATSIZE];
 967
 968                 dns_name_format(name, printname, sizeof(printname));
 969                 isc_log_write(dns_lctx, DNS_LOGCATEGORY_RPZ,
 970                               DNS_LOGMODULE_RBTDB, DNS_RPZ_ERROR_LEVEL,
 971                               "duplicate rpz name \"%s\"", printname);
 972         }
 973 }
 974
 975 /*
 976  * Delete an IP address from the radix tree of a response policy database.
 977  *      The tree write lock must be held by the caller.
 978  */
 979 void
 980 dns_rpz_cidr_deleteip(dns_rpz_cidr_t *cidr, dns_name_t *name) {
 981         dns_rpz_cidr_key_t tgt_ip;
 982         dns_rpz_cidr_bits_t tgt_prefix;
 983         dns_rpz_type_t type;
 984         dns_rpz_cidr_node_t *tgt = NULL, *parent, *child;
 985         dns_rpz_cidr_flags_t flags, data_flag;
 986
 987         if (cidr == NULL)
 988                 return;
 989
 990         /*
 991          * Decide which kind of policy zone IP address it is, if either
 992          * and then find its node.
 993          */
 994         type = set_type(cidr, name);
 995         switch (type) {
 996         case DNS_RPZ_TYPE_IP:
 997         case DNS_RPZ_TYPE_NSIP:
 998                 break;
 999         case DNS_RPZ_TYPE_NSDNAME:
1000                 /*
1001                  * We cannot easily count nsdnames because
1002                  * internal rbt nodes get deleted.
1003                  */
1004                 return;
1005         case DNS_RPZ_TYPE_QNAME:
1006         case DNS_RPZ_TYPE_BAD:
1007                 return;
1008         }
1009
1010         /*
1011          * Do not get excited about the deletion of interior rbt nodes.
1012          */
1013         if (ISC_R_SUCCESS != name2ipkey(cidr, DNS_RPZ_DEBUG_LEVEL3, name,
1014                                         type, &tgt_ip, &tgt_prefix))
1015                 return;
1016         if (ISC_R_SUCCESS != search(cidr, &tgt_ip, tgt_prefix, type,
1017                                     ISC_FALSE, &tgt)) {
1018                 if (isc_log_wouldlog(dns_lctx, DNS_RPZ_ERROR_LEVEL)) {
1019                         char printname[DNS_NAME_FORMATSIZE];
1020
1021                         dns_name_format(name, printname, sizeof(printname));
1022                         isc_log_write(dns_lctx, DNS_LOGCATEGORY_RPZ,
1023                                       DNS_LOGMODULE_RBTDB, DNS_RPZ_ERROR_LEVEL,
1024                                       "missing rpz node \"%s\"", printname);
1025                 }
1026                 return;
1027         }
1028
1029         /*
1030          * Mark the node and its parents to reflect the deleted IP address.
1031          */
1032         flags = get_flags(&tgt_ip, tgt_prefix, type);
1033         data_flag = flags & (DNS_RPZ_CIDR_FG_IP_DATA |
1034                               DNS_RPZ_CIDR_FG_NSIP_DATA);
1035         tgt->flags &= ~data_flag;
1036         for (parent = tgt; parent != NULL; parent = parent->parent) {
1037                 if ((parent->flags & data_flag) != 0 ||
1038                     (parent->child[0] != NULL &&
1039                      (parent->child[0]->flags & flags) != 0) ||
1040                     (parent->child[1] != NULL &&
1041                      (parent->child[1]->flags & flags) != 0))
1042                         break;
1043                 parent->flags &= ~flags;
1044         }
1045
1046         /*
1047          * We might need to delete 2 nodes.
1048          */
1049         do {
1050                 /*
1051                  * The node is now useless if it has no data of its own
1052                  * and 0 or 1 children.  We are finished if it is not useless.
1053                  */
1054                 if ((child = tgt->child[0]) != NULL) {
1055                         if (tgt->child[1] != NULL)
1056                                 return;
1057                 } else {
1058                         child = tgt->child[1];
1059                 }
1060                 if ((tgt->flags & (DNS_RPZ_CIDR_FG_IP_DATA |
1061                                  DNS_RPZ_CIDR_FG_NSIP_DATA)) != 0)
1062                         return;
1063
1064                 /*
1065                  * Replace the pointer to this node in the parent with
1066                  * the remaining child or NULL.
1067                  */
1068                 parent = tgt->parent;
1069                 if (parent == NULL) {
1070                         cidr->root = child;
1071                 } else {
1072                         parent->child[parent->child[1] == tgt] = child;
1073                 }
1074                 /*
1075                  * If the child exists fix up its parent pointer.
1076                  */
1077                 if (child != NULL)
1078                         child->parent = parent;
1079                 isc_mem_put(cidr->mctx, tgt, sizeof(*tgt));
1080
1081                 tgt = parent;
1082         } while (tgt != NULL);
1083 }
1084
1085 /*
1086  * Caller must hold tree lock.
1087  * Return  ISC_R_NOTFOUND
1088  *      or ISC_R_SUCCESS and the found entry's canonical and search names
1089  *          and its prefix length
1090  */
1091 isc_result_t
1092 dns_rpz_cidr_find(dns_rpz_cidr_t *cidr, const isc_netaddr_t *netaddr,
1093                   dns_rpz_type_t type, dns_name_t *canon_name,
1094                   dns_name_t *search_name, dns_rpz_cidr_bits_t *prefix)
1095 {
1096         dns_rpz_cidr_key_t tgt_ip;
1097         isc_result_t result;
1098         dns_rpz_cidr_node_t *found;
1099         int i;
1100
1101         /*
1102          * Convert IP address to CIDR tree key.
1103          */
1104         if (netaddr->family == AF_INET) {
1105                 tgt_ip.w[0] = 0;
1106                 tgt_ip.w[1] = 0;
1107                 tgt_ip.w[2] = ADDR_V4MAPPED;
1108                 tgt_ip.w[3] = ntohl(netaddr->type.in.s_addr);
1109         } else if (netaddr->family == AF_INET6) {
1110                 dns_rpz_cidr_key_t src_ip6;
1111
1112                 /*
1113                  * Given the int aligned struct in_addr member of netaddr->type
1114                  * one could cast netaddr->type.in6 to dns_rpz_cidr_key_t *,
1115                  * but there are objections.
1116                  */
1117                 memcpy(src_ip6.w, &netaddr->type.in6, sizeof(src_ip6.w));
1118                 for (i = 0; i < 4; i++) {
1119                         tgt_ip.w[i] = ntohl(src_ip6.w[i]);
1120                 }
1121         } else {
1122                 return (ISC_R_NOTFOUND);
1123         }
1124
1125         result = search(cidr, &tgt_ip, 128, type, ISC_FALSE, &found);
1126         if (result != ISC_R_SUCCESS && result != DNS_R_PARTIALMATCH)
1127                 return (result);
1128
1129         *prefix = found->bits;
1130         return (ip2name(cidr, &found->ip, found->bits, type,
1131                         canon_name, search_name));
1132 }
1133
1134 /*
1135  * Translate CNAME rdata to a QNAME response policy action.
1136  */
1137 dns_rpz_policy_t
1138 dns_rpz_decode_cname(dns_rdataset_t *rdataset, dns_name_t *selfname) {
1139         dns_rdata_t rdata = DNS_RDATA_INIT;
1140         dns_rdata_cname_t cname;
1141         isc_result_t result;
1142
1143         result = dns_rdataset_first(rdataset);
1144         RUNTIME_CHECK(result == ISC_R_SUCCESS);
1145         dns_rdataset_current(rdataset, &rdata);
1146         result = dns_rdata_tostruct(&rdata, &cname, NULL);
1147         RUNTIME_CHECK(result == ISC_R_SUCCESS);
1148         dns_rdata_reset(&rdata);
1149
1150         /*
1151          * CNAME . means NXDOMAIN
1152          */
1153         if (dns_name_equal(&cname.cname, dns_rootname))
1154                 return (DNS_RPZ_POLICY_NXDOMAIN);
1155
1156         if (dns_name_iswildcard(&cname.cname)) {
1157                 /*
1158                  * CNAME *. means NODATA
1159                  */
1160                 if (dns_name_countlabels(&cname.cname) == 2)
1161                         return (DNS_RPZ_POLICY_NODATA);
1162
1163                 /*
1164                  * A qname of www.evil.com and a policy of
1165                  *      *.evil.com    CNAME   *.garden.net
1166                  * gives a result of
1167                  *      evil.com    CNAME   evil.com.garden.net
1168                  */
1169                 if (dns_name_countlabels(&cname.cname) > 2)
1170                         return (DNS_RPZ_POLICY_WILDCNAME);
1171         }
1172
1173         /*
1174          * 128.1.0.127.rpz-ip CNAME  128.1.0.0.127. means "do not rewrite"
1175          */
1176         if (selfname != NULL && dns_name_equal(&cname.cname, selfname))
1177                 return (DNS_RPZ_POLICY_PASSTHRU);
1178
1179         /*
1180          * Any other rdata gives a response consisting of the rdata.
1181          */
1182         return (DNS_RPZ_POLICY_RECORD);
1183 }