contrib/unbound/iterator/iter_utils.c

   1 /*
   2  * iterator/iter_utils.c - iterative resolver module utility functions.
   3  *
   4  * Copyright (c) 2007, NLnet Labs. All rights reserved.
   5  *
   6  * This software is open source.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * Redistributions of source code must retain the above copyright notice,
  13  * this list of conditions and the following disclaimer.
  14  *
  15  * Redistributions in binary form must reproduce the above copyright notice,
  16  * this list of conditions and the following disclaimer in the documentation
  17  * and/or other materials provided with the distribution.
  18  *
  19  * Neither the name of the NLNET LABS nor the names of its contributors may
  20  * be used to endorse or promote products derived from this software without
  21  * specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  24  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  25  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  26  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  27  * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
  29  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  30  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  31  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  32  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  33  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 /**
  37  * \file
  38  *
  39  * This file contains functions to assist the iterator module.
  40  * Configuration options. Forward zones.
  41  */
  42 #include "config.h"
  43 #include "iterator/iter_utils.h"
  44 #include "iterator/iterator.h"
  45 #include "iterator/iter_hints.h"
  46 #include "iterator/iter_fwd.h"
  47 #include "iterator/iter_donotq.h"
  48 #include "iterator/iter_delegpt.h"
  49 #include "iterator/iter_priv.h"
  50 #include "services/cache/infra.h"
  51 #include "services/cache/dns.h"
  52 #include "services/cache/rrset.h"
  53 #include "util/net_help.h"
  54 #include "util/module.h"
  55 #include "util/log.h"
  56 #include "util/config_file.h"
  57 #include "util/regional.h"
  58 #include "util/data/msgparse.h"
  59 #include "util/data/dname.h"
  60 #include "util/random.h"
  61 #include "util/fptr_wlist.h"
  62 #include "validator/val_anchor.h"
  63 #include "validator/val_kcache.h"
  64 #include "validator/val_kentry.h"
  65 #include "validator/val_utils.h"
  66 #include "validator/val_sigcrypt.h"
  67 #include "sldns/sbuffer.h"
  68 #include "sldns/str2wire.h"
  69
  70 /** time when nameserver glue is said to be 'recent' */
  71 #define SUSPICION_RECENT_EXPIRY 86400
  72 /** penalty to validation failed blacklisted IPs */
  73 #define BLACKLIST_PENALTY (USEFUL_SERVER_TOP_TIMEOUT*4)
  74
  75 /** fillup fetch policy array */
  76 static void
  77 fetch_fill(struct iter_env* ie, const char* str)
  78 {
  79         char* s = (char*)str, *e;
  80         int i;
  81         for(i=0; i<ie->max_dependency_depth+1; i++) {
  82                 ie->target_fetch_policy[i] = strtol(s, &e, 10);
  83                 if(s == e)
  84                         fatal_exit("cannot parse fetch policy number %s", s);
  85                 s = e;
  86         }
  87 }
  88
  89 /** Read config string that represents the target fetch policy */
  90 static int
  91 read_fetch_policy(struct iter_env* ie, const char* str)
  92 {
  93         int count = cfg_count_numbers(str);
  94         if(count < 1) {
  95                 log_err("Cannot parse target fetch policy: \"%s\"", str);
  96                 return 0;
  97         }
  98         ie->max_dependency_depth = count - 1;
  99         ie->target_fetch_policy = (int*)calloc(
 100                 (size_t)ie->max_dependency_depth+1, sizeof(int));
 101         if(!ie->target_fetch_policy) {
 102                 log_err("alloc fetch policy: out of memory");
 103                 return 0;
 104         }
 105         fetch_fill(ie, str);
 106         return 1;
 107 }
 108
 109 /** apply config caps whitelist items to name tree */
 110 static int
 111 caps_white_apply_cfg(rbtree_t* ntree, struct config_file* cfg)
 112 {
 113         struct config_strlist* p;
 114         for(p=cfg->caps_whitelist; p; p=p->next) {
 115                 struct name_tree_node* n;
 116                 size_t len;
 117                 uint8_t* nm = sldns_str2wire_dname(p->str, &len);
 118                 if(!nm) {
 119                         log_err("could not parse %s", p->str);
 120                         return 0;
 121                 }
 122                 n = (struct name_tree_node*)calloc(1, sizeof(*n));
 123                 if(!n) {
 124                         log_err("out of memory");
 125                         free(nm);
 126                         return 0;
 127                 }
 128                 n->node.key = n;
 129                 n->name = nm;
 130                 n->len = len;
 131                 n->labs = dname_count_labels(nm);
 132                 n->dclass = LDNS_RR_CLASS_IN;
 133                 if(!name_tree_insert(ntree, n, nm, len, n->labs, n->dclass)) {
 134                         /* duplicate element ignored, idempotent */
 135                         free(n->name);
 136                         free(n);
 137                 }
 138         }
 139         name_tree_init_parents(ntree);
 140         return 1;
 141 }
 142
 143 int
 144 iter_apply_cfg(struct iter_env* iter_env, struct config_file* cfg)
 145 {
 146         int i;
 147         /* target fetch policy */
 148         if(!read_fetch_policy(iter_env, cfg->target_fetch_policy))
 149                 return 0;
 150         for(i=0; i<iter_env->max_dependency_depth+1; i++)
 151                 verbose(VERB_QUERY, "target fetch policy for level %d is %d",
 152                         i, iter_env->target_fetch_policy[i]);
 153
 154         if(!iter_env->donotq)
 155                 iter_env->donotq = donotq_create();
 156         if(!iter_env->donotq || !donotq_apply_cfg(iter_env->donotq, cfg)) {
 157                 log_err("Could not set donotqueryaddresses");
 158                 return 0;
 159         }
 160         if(!iter_env->priv)
 161                 iter_env->priv = priv_create();
 162         if(!iter_env->priv || !priv_apply_cfg(iter_env->priv, cfg)) {
 163                 log_err("Could not set private addresses");
 164                 return 0;
 165         }
 166         if(cfg->caps_whitelist) {
 167                 if(!iter_env->caps_white)
 168                         iter_env->caps_white = rbtree_create(name_tree_compare);
 169                 if(!iter_env->caps_white || !caps_white_apply_cfg(
 170                         iter_env->caps_white, cfg)) {
 171                         log_err("Could not set capsforid whitelist");
 172                         return 0;
 173                 }
 174
 175         }
 176         iter_env->supports_ipv6 = cfg->do_ip6;
 177         iter_env->supports_ipv4 = cfg->do_ip4;
 178         return 1;
 179 }
 180
 181 /** filter out unsuitable targets
 182  * @param iter_env: iterator environment with ipv6-support flag.
 183  * @param env: module environment with infra cache.
 184  * @param name: zone name
 185  * @param namelen: length of name
 186  * @param qtype: query type (host order).
 187  * @param now: current time
 188  * @param a: address in delegation point we are examining.
 189  * @return an integer that signals the target suitability.
 190  *      as follows:
 191  *      -1: The address should be omitted from the list.
 192  *          Because:
 193  *              o The address is bogus (DNSSEC validation failure).
 194  *              o Listed as donotquery
 195  *              o is ipv6 but no ipv6 support (in operating system).
 196  *              o is ipv4 but no ipv4 support (in operating system).
 197  *              o is lame
 198  *      Otherwise, an rtt in milliseconds.
 199  *      0 .. USEFUL_SERVER_TOP_TIMEOUT-1
 200  *              The roundtrip time timeout estimate. less than 2 minutes.
 201  *              Note that util/rtt.c has a MIN_TIMEOUT of 50 msec, thus
 202  *              values 0 .. 49 are not used, unless that is changed.
 203  *      USEFUL_SERVER_TOP_TIMEOUT
 204  *              This value exactly is given for unresponsive blacklisted.
 205  *      USEFUL_SERVER_TOP_TIMEOUT+1
 206  *              For non-blacklisted servers: huge timeout, but has traffic.
 207  *      USEFUL_SERVER_TOP_TIMEOUT*1 ..
 208  *              parent-side lame servers get this penalty. A dispreferential
 209  *              server. (lame in delegpt).
 210  *      USEFUL_SERVER_TOP_TIMEOUT*2 ..
 211  *              dnsseclame servers get penalty
 212  *      USEFUL_SERVER_TOP_TIMEOUT*3 ..
 213  *              recursion lame servers get penalty
 214  *      UNKNOWN_SERVER_NICENESS
 215  *              If no information is known about the server, this is
 216  *              returned. 376 msec or so.
 217  *      +BLACKLIST_PENALTY (of USEFUL_TOP_TIMEOUT*4) for dnssec failed IPs.
 218  *
 219  * When a final value is chosen that is dnsseclame ; dnsseclameness checking
 220  * is turned off (so we do not discard the reply).
 221  * When a final value is chosen that is recursionlame; RD bit is set on query.
 222  * Because of the numbers this means recursionlame also have dnssec lameness
 223  * checking turned off.
 224  */
 225 static int
 226 iter_filter_unsuitable(struct iter_env* iter_env, struct module_env* env,
 227         uint8_t* name, size_t namelen, uint16_t qtype, time_t now,
 228         struct delegpt_addr* a)
 229 {
 230         int rtt, lame, reclame, dnsseclame;
 231         if(a->bogus)
 232                 return -1; /* address of server is bogus */
 233         if(donotq_lookup(iter_env->donotq, &a->addr, a->addrlen)) {
 234                 log_addr(VERB_ALGO, "skip addr on the donotquery list",
 235                         &a->addr, a->addrlen);
 236                 return -1; /* server is on the donotquery list */
 237         }
 238         if(!iter_env->supports_ipv6 && addr_is_ip6(&a->addr, a->addrlen)) {
 239                 return -1; /* there is no ip6 available */
 240         }
 241         if(!iter_env->supports_ipv4 && !addr_is_ip6(&a->addr, a->addrlen)) {
 242                 return -1; /* there is no ip4 available */
 243         }
 244         /* check lameness - need zone , class info */
 245         if(infra_get_lame_rtt(env->infra_cache, &a->addr, a->addrlen,
 246                 name, namelen, qtype, &lame, &dnsseclame, &reclame,
 247                 &rtt, now)) {
 248                 log_addr(VERB_ALGO, "servselect", &a->addr, a->addrlen);
 249                 verbose(VERB_ALGO, "   rtt=%d%s%s%s%s", rtt,
 250                         lame?" LAME":"",
 251                         dnsseclame?" DNSSEC_LAME":"",
 252                         reclame?" REC_LAME":"",
 253                         a->lame?" ADDR_LAME":"");
 254                 if(lame)
 255                         return -1; /* server is lame */
 256                 else if(rtt >= USEFUL_SERVER_TOP_TIMEOUT)
 257                         /* server is unresponsive,
 258                          * we used to return TOP_TIMEOUT, but fairly useless,
 259                          * because if == TOP_TIMEOUT is dropped because
 260                          * blacklisted later, instead, remove it here, so
 261                          * other choices (that are not blacklisted) can be
 262                          * tried */
 263                         return -1;
 264                 /* select remainder from worst to best */
 265                 else if(reclame)
 266                         return rtt+USEFUL_SERVER_TOP_TIMEOUT*3; /* nonpref */
 267                 else if(dnsseclame || a->dnsseclame)
 268                         return rtt+USEFUL_SERVER_TOP_TIMEOUT*2; /* nonpref */
 269                 else if(a->lame)
 270                         return rtt+USEFUL_SERVER_TOP_TIMEOUT+1; /* nonpref */
 271                 else    return rtt;
 272         }
 273         /* no server information present */
 274         if(a->dnsseclame)
 275                 return UNKNOWN_SERVER_NICENESS+USEFUL_SERVER_TOP_TIMEOUT*2; /* nonpref */
 276         else if(a->lame)
 277                 return USEFUL_SERVER_TOP_TIMEOUT+1+UNKNOWN_SERVER_NICENESS; /* nonpref */
 278         return UNKNOWN_SERVER_NICENESS;
 279 }
 280
 281 /** lookup RTT information, and also store fastest rtt (if any) */
 282 static int
 283 iter_fill_rtt(struct iter_env* iter_env, struct module_env* env,
 284         uint8_t* name, size_t namelen, uint16_t qtype, time_t now,
 285         struct delegpt* dp, int* best_rtt, struct sock_list* blacklist)
 286 {
 287         int got_it = 0;
 288         struct delegpt_addr* a;
 289         if(dp->bogus)
 290                 return 0; /* NS bogus, all bogus, nothing found */
 291         for(a=dp->result_list; a; a = a->next_result) {
 292                 a->sel_rtt = iter_filter_unsuitable(iter_env, env,
 293                         name, namelen, qtype, now, a);
 294                 if(a->sel_rtt != -1) {
 295                         if(sock_list_find(blacklist, &a->addr, a->addrlen))
 296                                 a->sel_rtt += BLACKLIST_PENALTY;
 297
 298                         if(!got_it) {
 299                                 *best_rtt = a->sel_rtt;
 300                                 got_it = 1;
 301                         } else if(a->sel_rtt < *best_rtt) {
 302                                 *best_rtt = a->sel_rtt;
 303                         }
 304                 }
 305         }
 306         return got_it;
 307 }
 308
 309 /** filter the address list, putting best targets at front,
 310  * returns number of best targets (or 0, no suitable targets) */
 311 static int
 312 iter_filter_order(struct iter_env* iter_env, struct module_env* env,
 313         uint8_t* name, size_t namelen, uint16_t qtype, time_t now,
 314         struct delegpt* dp, int* selected_rtt, int open_target,
 315         struct sock_list* blacklist)
 316 {
 317         int got_num = 0, low_rtt = 0, swap_to_front;
 318         struct delegpt_addr* a, *n, *prev=NULL;
 319
 320         /* fillup sel_rtt and find best rtt in the bunch */
 321         got_num = iter_fill_rtt(iter_env, env, name, namelen, qtype, now, dp,
 322                 &low_rtt, blacklist);
 323         if(got_num == 0)
 324                 return 0;
 325         if(low_rtt >= USEFUL_SERVER_TOP_TIMEOUT &&
 326                 (delegpt_count_missing_targets(dp) > 0 || open_target > 0)) {
 327                 verbose(VERB_ALGO, "Bad choices, trying to get more choice");
 328                 return 0; /* we want more choice. The best choice is a bad one.
 329                              return 0 to force the caller to fetch more */
 330         }
 331
 332         got_num = 0;
 333         a = dp->result_list;
 334         while(a) {
 335                 /* skip unsuitable targets */
 336                 if(a->sel_rtt == -1) {
 337                         prev = a;
 338                         a = a->next_result;
 339                         continue;
 340                 }
 341                 /* classify the server address and determine what to do */
 342                 swap_to_front = 0;
 343                 if(a->sel_rtt >= low_rtt && a->sel_rtt - low_rtt <= RTT_BAND) {
 344                         got_num++;
 345                         swap_to_front = 1;
 346                 } else if(a->sel_rtt<low_rtt && low_rtt-a->sel_rtt<=RTT_BAND) {
 347                         got_num++;
 348                         swap_to_front = 1;
 349                 }
 350                 /* swap to front if necessary, or move to next result */
 351                 if(swap_to_front && prev) {
 352                         n = a->next_result;
 353                         prev->next_result = n;
 354                         a->next_result = dp->result_list;
 355                         dp->result_list = a;
 356                         a = n;
 357                 } else {
 358                         prev = a;
 359                         a = a->next_result;
 360                 }
 361         }
 362         *selected_rtt = low_rtt;
 363         return got_num;
 364 }
 365
 366 struct delegpt_addr*
 367 iter_server_selection(struct iter_env* iter_env,
 368         struct module_env* env, struct delegpt* dp,
 369         uint8_t* name, size_t namelen, uint16_t qtype, int* dnssec_lame,
 370         int* chase_to_rd, int open_target, struct sock_list* blacklist)
 371 {
 372         int sel;
 373         int selrtt;
 374         struct delegpt_addr* a, *prev;
 375         int num = iter_filter_order(iter_env, env, name, namelen, qtype,
 376                 *env->now, dp, &selrtt, open_target, blacklist);
 377
 378         if(num == 0)
 379                 return NULL;
 380         verbose(VERB_ALGO, "selrtt %d", selrtt);
 381         if(selrtt > BLACKLIST_PENALTY) {
 382                 if(selrtt-BLACKLIST_PENALTY > USEFUL_SERVER_TOP_TIMEOUT*3) {
 383                         verbose(VERB_ALGO, "chase to "
 384                                 "blacklisted recursion lame server");
 385                         *chase_to_rd = 1;
 386                 }
 387                 if(selrtt-BLACKLIST_PENALTY > USEFUL_SERVER_TOP_TIMEOUT*2) {
 388                         verbose(VERB_ALGO, "chase to "
 389                                 "blacklisted dnssec lame server");
 390                         *dnssec_lame = 1;
 391                 }
 392         } else {
 393                 if(selrtt > USEFUL_SERVER_TOP_TIMEOUT*3) {
 394                         verbose(VERB_ALGO, "chase to recursion lame server");
 395                         *chase_to_rd = 1;
 396                 }
 397                 if(selrtt > USEFUL_SERVER_TOP_TIMEOUT*2) {
 398                         verbose(VERB_ALGO, "chase to dnssec lame server");
 399                         *dnssec_lame = 1;
 400                 }
 401                 if(selrtt == USEFUL_SERVER_TOP_TIMEOUT) {
 402                         verbose(VERB_ALGO, "chase to blacklisted lame server");
 403                         return NULL;
 404                 }
 405         }
 406
 407         if(num == 1) {
 408                 a = dp->result_list;
 409                 if(++a->attempts < OUTBOUND_MSG_RETRY)
 410                         return a;
 411                 dp->result_list = a->next_result;
 412                 return a;
 413         }
 414
 415         /* randomly select a target from the list */
 416         log_assert(num > 1);
 417         /* grab secure random number, to pick unexpected server.
 418          * also we need it to be threadsafe. */
 419         sel = ub_random_max(env->rnd, num);
 420         a = dp->result_list;
 421         prev = NULL;
 422         while(sel > 0 && a) {
 423                 prev = a;
 424                 a = a->next_result;
 425                 sel--;
 426         }
 427         if(!a)  /* robustness */
 428                 return NULL;
 429         if(++a->attempts < OUTBOUND_MSG_RETRY)
 430                 return a;
 431         /* remove it from the delegation point result list */
 432         if(prev)
 433                 prev->next_result = a->next_result;
 434         else    dp->result_list = a->next_result;
 435         return a;
 436 }
 437
 438 struct dns_msg*
 439 dns_alloc_msg(sldns_buffer* pkt, struct msg_parse* msg,
 440         struct regional* region)
 441 {
 442         struct dns_msg* m = (struct dns_msg*)regional_alloc(region,
 443                 sizeof(struct dns_msg));
 444         if(!m)
 445                 return NULL;
 446         memset(m, 0, sizeof(*m));
 447         if(!parse_create_msg(pkt, msg, NULL, &m->qinfo, &m->rep, region)) {
 448                 log_err("malloc failure: allocating incoming dns_msg");
 449                 return NULL;
 450         }
 451         return m;
 452 }
 453
 454 struct dns_msg*
 455 dns_copy_msg(struct dns_msg* from, struct regional* region)
 456 {
 457         struct dns_msg* m = (struct dns_msg*)regional_alloc(region,
 458                 sizeof(struct dns_msg));
 459         if(!m)
 460                 return NULL;
 461         m->qinfo = from->qinfo;
 462         if(!(m->qinfo.qname = regional_alloc_init(region, from->qinfo.qname,
 463                 from->qinfo.qname_len)))
 464                 return NULL;
 465         if(!(m->rep = reply_info_copy(from->rep, NULL, region)))
 466                 return NULL;
 467         return m;
 468 }
 469
 470 void
 471 iter_dns_store(struct module_env* env, struct query_info* msgqinf,
 472         struct reply_info* msgrep, int is_referral, time_t leeway, int pside,
 473         struct regional* region, uint16_t flags)
 474 {
 475         if(!dns_cache_store(env, msgqinf, msgrep, is_referral, leeway,
 476                 pside, region, flags))
 477                 log_err("out of memory: cannot store data in cache");
 478 }
 479
 480 int
 481 iter_ns_probability(struct ub_randstate* rnd, int n, int m)
 482 {
 483         int sel;
 484         if(n == m) /* 100% chance */
 485                 return 1;
 486         /* we do not need secure random numbers here, but
 487          * we do need it to be threadsafe, so we use this */
 488         sel = ub_random_max(rnd, m);
 489         return (sel < n);
 490 }
 491
 492 /** detect dependency cycle for query and target */
 493 static int
 494 causes_cycle(struct module_qstate* qstate, uint8_t* name, size_t namelen,
 495         uint16_t t, uint16_t c)
 496 {
 497         struct query_info qinf;
 498         qinf.qname = name;
 499         qinf.qname_len = namelen;
 500         qinf.qtype = t;
 501         qinf.qclass = c;
 502         fptr_ok(fptr_whitelist_modenv_detect_cycle(
 503                 qstate->env->detect_cycle));
 504         return (*qstate->env->detect_cycle)(qstate, &qinf,
 505                 (uint16_t)(BIT_RD|BIT_CD), qstate->is_priming,
 506                 qstate->is_valrec);
 507 }
 508
 509 void
 510 iter_mark_cycle_targets(struct module_qstate* qstate, struct delegpt* dp)
 511 {
 512         struct delegpt_ns* ns;
 513         for(ns = dp->nslist; ns; ns = ns->next) {
 514                 if(ns->resolved)
 515                         continue;
 516                 /* see if this ns as target causes dependency cycle */
 517                 if(causes_cycle(qstate, ns->name, ns->namelen,
 518                         LDNS_RR_TYPE_AAAA, qstate->qinfo.qclass) ||
 519                    causes_cycle(qstate, ns->name, ns->namelen,
 520                         LDNS_RR_TYPE_A, qstate->qinfo.qclass)) {
 521                         log_nametypeclass(VERB_QUERY, "skipping target due "
 522                                 "to dependency cycle (harden-glue: no may "
 523                                 "fix some of the cycles)",
 524                                 ns->name, LDNS_RR_TYPE_A,
 525                                 qstate->qinfo.qclass);
 526                         ns->resolved = 1;
 527                 }
 528         }
 529 }
 530
 531 void
 532 iter_mark_pside_cycle_targets(struct module_qstate* qstate, struct delegpt* dp)
 533 {
 534         struct delegpt_ns* ns;
 535         for(ns = dp->nslist; ns; ns = ns->next) {
 536                 if(ns->done_pside4 && ns->done_pside6)
 537                         continue;
 538                 /* see if this ns as target causes dependency cycle */
 539                 if(causes_cycle(qstate, ns->name, ns->namelen,
 540                         LDNS_RR_TYPE_A, qstate->qinfo.qclass)) {
 541                         log_nametypeclass(VERB_QUERY, "skipping target due "
 542                                 "to dependency cycle", ns->name,
 543                                 LDNS_RR_TYPE_A, qstate->qinfo.qclass);
 544                         ns->done_pside4 = 1;
 545                 }
 546                 if(causes_cycle(qstate, ns->name, ns->namelen,
 547                         LDNS_RR_TYPE_AAAA, qstate->qinfo.qclass)) {
 548                         log_nametypeclass(VERB_QUERY, "skipping target due "
 549                                 "to dependency cycle", ns->name,
 550                                 LDNS_RR_TYPE_AAAA, qstate->qinfo.qclass);
 551                         ns->done_pside6 = 1;
 552                 }
 553         }
 554 }
 555
 556 int
 557 iter_dp_is_useless(struct query_info* qinfo, uint16_t qflags,
 558         struct delegpt* dp)
 559 {
 560         struct delegpt_ns* ns;
 561         /* check:
 562          *      o RD qflag is on.
 563          *      o no addresses are provided.
 564          *      o all NS items are required glue.
 565          * OR
 566          *      o RD qflag is on.
 567          *      o no addresses are provided.
 568          *      o the query is for one of the nameservers in dp,
 569          *        and that nameserver is a glue-name for this dp.
 570          */
 571         if(!(qflags&BIT_RD))
 572                 return 0;
 573         /* either available or unused targets */
 574         if(dp->usable_list || dp->result_list)
 575                 return 0;
 576
 577         /* see if query is for one of the nameservers, which is glue */
 578         if( (qinfo->qtype == LDNS_RR_TYPE_A ||
 579                 qinfo->qtype == LDNS_RR_TYPE_AAAA) &&
 580                 dname_subdomain_c(qinfo->qname, dp->name) &&
 581                 delegpt_find_ns(dp, qinfo->qname, qinfo->qname_len))
 582                 return 1;
 583
 584         for(ns = dp->nslist; ns; ns = ns->next) {
 585                 if(ns->resolved) /* skip failed targets */
 586                         continue;
 587                 if(!dname_subdomain_c(ns->name, dp->name))
 588                         return 0; /* one address is not required glue */
 589         }
 590         return 1;
 591 }
 592
 593 int
 594 iter_indicates_dnssec(struct module_env* env, struct delegpt* dp,
 595         struct dns_msg* msg, uint16_t dclass)
 596 {
 597         struct trust_anchor* a;
 598         /* information not available, !env->anchors can be common */
 599         if(!env || !env->anchors || !dp || !dp->name)
 600                 return 0;
 601         /* a trust anchor exists with this name, RRSIGs expected */
 602         if((a=anchor_find(env->anchors, dp->name, dp->namelabs, dp->namelen,
 603                 dclass))) {
 604                 lock_basic_unlock(&a->lock);
 605                 return 1;
 606         }
 607         /* see if DS rrset was given, in AUTH section */
 608         if(msg && msg->rep &&
 609                 reply_find_rrset_section_ns(msg->rep, dp->name, dp->namelen,
 610                 LDNS_RR_TYPE_DS, dclass))
 611                 return 1;
 612         /* look in key cache */
 613         if(env->key_cache) {
 614                 struct key_entry_key* kk = key_cache_obtain(env->key_cache,
 615                         dp->name, dp->namelen, dclass, env->scratch, *env->now);
 616                 if(kk) {
 617                         if(query_dname_compare(kk->name, dp->name) == 0) {
 618                           if(key_entry_isgood(kk) || key_entry_isbad(kk)) {
 619                                 regional_free_all(env->scratch);
 620                                 return 1;
 621                           } else if(key_entry_isnull(kk)) {
 622                                 regional_free_all(env->scratch);
 623                                 return 0;
 624                           }
 625                         }
 626                         regional_free_all(env->scratch);
 627                 }
 628         }
 629         return 0;
 630 }
 631
 632 int
 633 iter_msg_has_dnssec(struct dns_msg* msg)
 634 {
 635         size_t i;
 636         if(!msg || !msg->rep)
 637                 return 0;
 638         for(i=0; i<msg->rep->an_numrrsets + msg->rep->ns_numrrsets; i++) {
 639                 if(((struct packed_rrset_data*)msg->rep->rrsets[i]->
 640                         entry.data)->rrsig_count > 0)
 641                         return 1;
 642         }
 643         /* empty message has no DNSSEC info, with DNSSEC the reply is
 644          * not empty (NSEC) */
 645         return 0;
 646 }
 647
 648 int iter_msg_from_zone(struct dns_msg* msg, struct delegpt* dp,
 649         enum response_type type, uint16_t dclass)
 650 {
 651         if(!msg || !dp || !msg->rep || !dp->name)
 652                 return 0;
 653         /* SOA RRset - always from reply zone */
 654         if(reply_find_rrset_section_an(msg->rep, dp->name, dp->namelen,
 655                 LDNS_RR_TYPE_SOA, dclass) ||
 656            reply_find_rrset_section_ns(msg->rep, dp->name, dp->namelen,
 657                 LDNS_RR_TYPE_SOA, dclass))
 658                 return 1;
 659         if(type == RESPONSE_TYPE_REFERRAL) {
 660                 size_t i;
 661                 /* if it adds a single label, i.e. we expect .com,
 662                  * and referral to example.com. NS ... , then origin zone
 663                  * is .com. For a referral to sub.example.com. NS ... then
 664                  * we do not know, since example.com. may be in between. */
 665                 for(i=0; i<msg->rep->an_numrrsets+msg->rep->ns_numrrsets;
 666                         i++) {
 667                         struct ub_packed_rrset_key* s = msg->rep->rrsets[i];
 668                         if(ntohs(s->rk.type) == LDNS_RR_TYPE_NS &&
 669                                 ntohs(s->rk.rrset_class) == dclass) {
 670                                 int l = dname_count_labels(s->rk.dname);
 671                                 if(l == dp->namelabs + 1 &&
 672                                         dname_strict_subdomain(s->rk.dname,
 673                                         l, dp->name, dp->namelabs))
 674                                         return 1;
 675                         }
 676                 }
 677                 return 0;
 678         }
 679         log_assert(type==RESPONSE_TYPE_ANSWER || type==RESPONSE_TYPE_CNAME);
 680         /* not a referral, and not lame delegation (upwards), so,
 681          * any NS rrset must be from the zone itself */
 682         if(reply_find_rrset_section_an(msg->rep, dp->name, dp->namelen,
 683                 LDNS_RR_TYPE_NS, dclass) ||
 684            reply_find_rrset_section_ns(msg->rep, dp->name, dp->namelen,
 685                 LDNS_RR_TYPE_NS, dclass))
 686                 return 1;
 687         /* a DNSKEY set is expected at the zone apex as well */
 688         /* this is for 'minimal responses' for DNSKEYs */
 689         if(reply_find_rrset_section_an(msg->rep, dp->name, dp->namelen,
 690                 LDNS_RR_TYPE_DNSKEY, dclass))
 691                 return 1;
 692         return 0;
 693 }
 694
 695 /**
 696  * check equality of two rrsets
 697  * @param k1: rrset
 698  * @param k2: rrset
 699  * @return true if equal
 700  */
 701 static int
 702 rrset_equal(struct ub_packed_rrset_key* k1, struct ub_packed_rrset_key* k2)
 703 {
 704         struct packed_rrset_data* d1 = (struct packed_rrset_data*)
 705                 k1->entry.data;
 706         struct packed_rrset_data* d2 = (struct packed_rrset_data*)
 707                 k2->entry.data;
 708         size_t i, t;
 709         if(k1->rk.dname_len != k2->rk.dname_len ||
 710                 k1->rk.flags != k2->rk.flags ||
 711                 k1->rk.type != k2->rk.type ||
 712                 k1->rk.rrset_class != k2->rk.rrset_class ||
 713                 query_dname_compare(k1->rk.dname, k2->rk.dname) != 0)
 714                 return 0;
 715         if(     /* do not check ttl: d1->ttl != d2->ttl || */
 716                 d1->count != d2->count ||
 717                 d1->rrsig_count != d2->rrsig_count ||
 718                 d1->trust != d2->trust ||
 719                 d1->security != d2->security)
 720                 return 0;
 721         t = d1->count + d1->rrsig_count;
 722         for(i=0; i<t; i++) {
 723                 if(d1->rr_len[i] != d2->rr_len[i] ||
 724                         /* no ttl check: d1->rr_ttl[i] != d2->rr_ttl[i] ||*/
 725                         memcmp(d1->rr_data[i], d2->rr_data[i],
 726                                 d1->rr_len[i]) != 0)
 727                         return 0;
 728         }
 729         return 1;
 730 }
 731
 732 int
 733 reply_equal(struct reply_info* p, struct reply_info* q, struct regional* region)
 734 {
 735         size_t i;
 736         if(p->flags != q->flags ||
 737                 p->qdcount != q->qdcount ||
 738                 /* do not check TTL, this may differ */
 739                 /*
 740                 p->ttl != q->ttl ||
 741                 p->prefetch_ttl != q->prefetch_ttl ||
 742                 */
 743                 p->security != q->security ||
 744                 p->an_numrrsets != q->an_numrrsets ||
 745                 p->ns_numrrsets != q->ns_numrrsets ||
 746                 p->ar_numrrsets != q->ar_numrrsets ||
 747                 p->rrset_count != q->rrset_count)
 748                 return 0;
 749         for(i=0; i<p->rrset_count; i++) {
 750                 if(!rrset_equal(p->rrsets[i], q->rrsets[i])) {
 751                         if(!rrset_canonical_equal(region, p->rrsets[i],
 752                                 q->rrsets[i])) {
 753                                 regional_free_all(region);
 754                                 return 0;
 755                         }
 756                         regional_free_all(region);
 757                 }
 758         }
 759         return 1;
 760 }
 761
 762 void
 763 caps_strip_reply(struct reply_info* rep)
 764 {
 765         size_t i;
 766         if(!rep) return;
 767         /* see if message is a referral, in which case the additional and
 768          * NS record cannot be removed */
 769         /* referrals have the AA flag unset (strict check, not elsewhere in
 770          * unbound, but for 0x20 this is very convenient). */
 771         if(!(rep->flags&BIT_AA))
 772                 return;
 773         /* remove the additional section from the reply */
 774         if(rep->ar_numrrsets != 0) {
 775                 verbose(VERB_ALGO, "caps fallback: removing additional section");
 776                 rep->rrset_count -= rep->ar_numrrsets;
 777                 rep->ar_numrrsets = 0;
 778         }
 779         /* is there an NS set in the authority section to remove? */
 780         /* the failure case (Cisco firewalls) only has one rrset in authsec */
 781         for(i=rep->an_numrrsets; i<rep->an_numrrsets+rep->ns_numrrsets; i++) {
 782                 struct ub_packed_rrset_key* s = rep->rrsets[i];
 783                 if(ntohs(s->rk.type) == LDNS_RR_TYPE_NS) {
 784                         /* remove NS rrset and break from loop (loop limits
 785                          * have changed) */
 786                         /* move last rrset into this position (there is no
 787                          * additional section any more) */
 788                         verbose(VERB_ALGO, "caps fallback: removing NS rrset");
 789                         if(i < rep->rrset_count-1)
 790                                 rep->rrsets[i]=rep->rrsets[rep->rrset_count-1];
 791                         rep->rrset_count --;
 792                         rep->ns_numrrsets --;
 793                         break;
 794                 }
 795         }
 796 }
 797
 798 int caps_failed_rcode(struct reply_info* rep)
 799 {
 800         return !(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR ||
 801                 FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN);
 802 }
 803
 804 void
 805 iter_store_parentside_rrset(struct module_env* env,
 806         struct ub_packed_rrset_key* rrset)
 807 {
 808         struct rrset_ref ref;
 809         rrset = packed_rrset_copy_alloc(rrset, env->alloc, *env->now);
 810         if(!rrset) {
 811                 log_err("malloc failure in store_parentside_rrset");
 812                 return;
 813         }
 814         rrset->rk.flags |= PACKED_RRSET_PARENT_SIDE;
 815         rrset->entry.hash = rrset_key_hash(&rrset->rk);
 816         ref.key = rrset;
 817         ref.id = rrset->id;
 818         /* ignore ret: if it was in the cache, ref updated */
 819         (void)rrset_cache_update(env->rrset_cache, &ref, env->alloc, *env->now);
 820 }
 821
 822 /** fetch NS record from reply, if any */
 823 static struct ub_packed_rrset_key*
 824 reply_get_NS_rrset(struct reply_info* rep)
 825 {
 826         size_t i;
 827         for(i=0; i<rep->rrset_count; i++) {
 828                 if(rep->rrsets[i]->rk.type == htons(LDNS_RR_TYPE_NS)) {
 829                         return rep->rrsets[i];
 830                 }
 831         }
 832         return NULL;
 833 }
 834
 835 void
 836 iter_store_parentside_NS(struct module_env* env, struct reply_info* rep)
 837 {
 838         struct ub_packed_rrset_key* rrset = reply_get_NS_rrset(rep);
 839         if(rrset) {
 840                 log_rrset_key(VERB_ALGO, "store parent-side NS", rrset);
 841                 iter_store_parentside_rrset(env, rrset);
 842         }
 843 }
 844
 845 void iter_store_parentside_neg(struct module_env* env,
 846         struct query_info* qinfo, struct reply_info* rep)
 847 {
 848         /* TTL: NS from referral in iq->deleg_msg,
 849          *      or first RR from iq->response,
 850          *      or servfail5secs if !iq->response */
 851         time_t ttl = NORR_TTL;
 852         struct ub_packed_rrset_key* neg;
 853         struct packed_rrset_data* newd;
 854         if(rep) {
 855                 struct ub_packed_rrset_key* rrset = reply_get_NS_rrset(rep);
 856                 if(!rrset && rep->rrset_count != 0) rrset = rep->rrsets[0];
 857                 if(rrset) ttl = ub_packed_rrset_ttl(rrset);
 858         }
 859         /* create empty rrset to store */
 860         neg = (struct ub_packed_rrset_key*)regional_alloc(env->scratch,
 861                         sizeof(struct ub_packed_rrset_key));
 862         if(!neg) {
 863                 log_err("out of memory in store_parentside_neg");
 864                 return;
 865         }
 866         memset(&neg->entry, 0, sizeof(neg->entry));
 867         neg->entry.key = neg;
 868         neg->rk.type = htons(qinfo->qtype);
 869         neg->rk.rrset_class = htons(qinfo->qclass);
 870         neg->rk.flags = 0;
 871         neg->rk.dname = regional_alloc_init(env->scratch, qinfo->qname,
 872                 qinfo->qname_len);
 873         if(!neg->rk.dname) {
 874                 log_err("out of memory in store_parentside_neg");
 875                 return;
 876         }
 877         neg->rk.dname_len = qinfo->qname_len;
 878         neg->entry.hash = rrset_key_hash(&neg->rk);
 879         newd = (struct packed_rrset_data*)regional_alloc_zero(env->scratch,
 880                 sizeof(struct packed_rrset_data) + sizeof(size_t) +
 881                 sizeof(uint8_t*) + sizeof(time_t) + sizeof(uint16_t));
 882         if(!newd) {
 883                 log_err("out of memory in store_parentside_neg");
 884                 return;
 885         }
 886         neg->entry.data = newd;
 887         newd->ttl = ttl;
 888         /* entry must have one RR, otherwise not valid in cache.
 889          * put in one RR with empty rdata: those are ignored as nameserver */
 890         newd->count = 1;
 891         newd->rrsig_count = 0;
 892         newd->trust = rrset_trust_ans_noAA;
 893         newd->rr_len = (size_t*)((uint8_t*)newd +
 894                 sizeof(struct packed_rrset_data));
 895         newd->rr_len[0] = 0 /* zero len rdata */ + sizeof(uint16_t);
 896         packed_rrset_ptr_fixup(newd);
 897         newd->rr_ttl[0] = newd->ttl;
 898         sldns_write_uint16(newd->rr_data[0], 0 /* zero len rdata */);
 899         /* store it */
 900         log_rrset_key(VERB_ALGO, "store parent-side negative", neg);
 901         iter_store_parentside_rrset(env, neg);
 902 }
 903
 904 int
 905 iter_lookup_parent_NS_from_cache(struct module_env* env, struct delegpt* dp,
 906         struct regional* region, struct query_info* qinfo)
 907 {
 908         struct ub_packed_rrset_key* akey;
 909         akey = rrset_cache_lookup(env->rrset_cache, dp->name,
 910                 dp->namelen, LDNS_RR_TYPE_NS, qinfo->qclass,
 911                 PACKED_RRSET_PARENT_SIDE, *env->now, 0);
 912         if(akey) {
 913                 log_rrset_key(VERB_ALGO, "found parent-side NS in cache", akey);
 914                 dp->has_parent_side_NS = 1;
 915                 /* and mark the new names as lame */
 916                 if(!delegpt_rrset_add_ns(dp, region, akey, 1)) {
 917                         lock_rw_unlock(&akey->entry.lock);
 918                         return 0;
 919                 }
 920                 lock_rw_unlock(&akey->entry.lock);
 921         }
 922         return 1;
 923 }
 924
 925 int iter_lookup_parent_glue_from_cache(struct module_env* env,
 926         struct delegpt* dp, struct regional* region, struct query_info* qinfo)
 927 {
 928         struct ub_packed_rrset_key* akey;
 929         struct delegpt_ns* ns;
 930         size_t num = delegpt_count_targets(dp);
 931         for(ns = dp->nslist; ns; ns = ns->next) {
 932                 /* get cached parentside A */
 933                 akey = rrset_cache_lookup(env->rrset_cache, ns->name,
 934                         ns->namelen, LDNS_RR_TYPE_A, qinfo->qclass,
 935                         PACKED_RRSET_PARENT_SIDE, *env->now, 0);
 936                 if(akey) {
 937                         log_rrset_key(VERB_ALGO, "found parent-side", akey);
 938                         ns->done_pside4 = 1;
 939                         /* a negative-cache-element has no addresses it adds */
 940                         if(!delegpt_add_rrset_A(dp, region, akey, 1))
 941                                 log_err("malloc failure in lookup_parent_glue");
 942                         lock_rw_unlock(&akey->entry.lock);
 943                 }
 944                 /* get cached parentside AAAA */
 945                 akey = rrset_cache_lookup(env->rrset_cache, ns->name,
 946                         ns->namelen, LDNS_RR_TYPE_AAAA, qinfo->qclass,
 947                         PACKED_RRSET_PARENT_SIDE, *env->now, 0);
 948                 if(akey) {
 949                         log_rrset_key(VERB_ALGO, "found parent-side", akey);
 950                         ns->done_pside6 = 1;
 951                         /* a negative-cache-element has no addresses it adds */
 952                         if(!delegpt_add_rrset_AAAA(dp, region, akey, 1))
 953                                 log_err("malloc failure in lookup_parent_glue");
 954                         lock_rw_unlock(&akey->entry.lock);
 955                 }
 956         }
 957         /* see if new (but lame) addresses have become available */
 958         return delegpt_count_targets(dp) != num;
 959 }
 960
 961 int
 962 iter_get_next_root(struct iter_hints* hints, struct iter_forwards* fwd,
 963         uint16_t* c)
 964 {
 965         uint16_t c1 = *c, c2 = *c;
 966         int r1 = hints_next_root(hints, &c1);
 967         int r2 = forwards_next_root(fwd, &c2);
 968         if(!r1 && !r2) /* got none, end of list */
 969                 return 0;
 970         else if(!r1) /* got one, return that */
 971                 *c = c2;
 972         else if(!r2)
 973                 *c = c1;
 974         else if(c1 < c2) /* got both take smallest */
 975                 *c = c1;
 976         else    *c = c2;
 977         return 1;
 978 }
 979
 980 void
 981 iter_scrub_ds(struct dns_msg* msg, struct ub_packed_rrset_key* ns, uint8_t* z)
 982 {
 983         /* Only the DS record for the delegation itself is expected.
 984          * We allow DS for everything between the bailiwick and the
 985          * zonecut, thus DS records must be at or above the zonecut.
 986          * And the DS records must be below the server authority zone.
 987          * The answer section is already scrubbed. */
 988         size_t i = msg->rep->an_numrrsets;
 989         while(i < (msg->rep->an_numrrsets + msg->rep->ns_numrrsets)) {
 990                 struct ub_packed_rrset_key* s = msg->rep->rrsets[i];
 991                 if(ntohs(s->rk.type) == LDNS_RR_TYPE_DS &&
 992                         (!ns || !dname_subdomain_c(ns->rk.dname, s->rk.dname)
 993                         || query_dname_compare(z, s->rk.dname) == 0)) {
 994                         log_nametypeclass(VERB_ALGO, "removing irrelevant DS",
 995                                 s->rk.dname, ntohs(s->rk.type),
 996                                 ntohs(s->rk.rrset_class));
 997                         memmove(msg->rep->rrsets+i, msg->rep->rrsets+i+1,
 998                                 sizeof(struct ub_packed_rrset_key*) *
 999                                 (msg->rep->rrset_count-i-1));
1000                         msg->rep->ns_numrrsets--;
1001                         msg->rep->rrset_count--;
1002                         /* stay at same i, but new record */
1003                         continue;
1004                 }
1005                 i++;
1006         }
1007 }
1008
1009 void iter_dec_attempts(struct delegpt* dp, int d)
1010 {
1011         struct delegpt_addr* a;
1012         for(a=dp->target_list; a; a = a->next_target) {
1013                 if(a->attempts >= OUTBOUND_MSG_RETRY) {
1014                         /* add back to result list */
1015                         a->next_result = dp->result_list;
1016                         dp->result_list = a;
1017                 }
1018                 if(a->attempts > d)
1019                         a->attempts -= d;
1020                 else a->attempts = 0;
1021         }
1022 }
1023
1024 void iter_merge_retry_counts(struct delegpt* dp, struct delegpt* old)
1025 {
1026         struct delegpt_addr* a, *o, *prev;
1027         for(a=dp->target_list; a; a = a->next_target) {
1028                 o = delegpt_find_addr(old, &a->addr, a->addrlen);
1029                 if(o) {
1030                         log_addr(VERB_ALGO, "copy attempt count previous dp",
1031                                 &a->addr, a->addrlen);
1032                         a->attempts = o->attempts;
1033                 }
1034         }
1035         prev = NULL;
1036         a = dp->usable_list;
1037         while(a) {
1038                 if(a->attempts >= OUTBOUND_MSG_RETRY) {
1039                         log_addr(VERB_ALGO, "remove from usable list dp",
1040                                 &a->addr, a->addrlen);
1041                         /* remove from result list */
1042                         if(prev)
1043                                 prev->next_usable = a->next_usable;
1044                         else    dp->usable_list = a->next_usable;
1045                         /* prev stays the same */
1046                         a = a->next_usable;
1047                         continue;
1048                 }
1049                 prev = a;
1050                 a = a->next_usable;
1051         }
1052 }
1053
1054 int
1055 iter_ds_toolow(struct dns_msg* msg, struct delegpt* dp)
1056 {
1057         /* if for query example.com, there is example.com SOA or a subdomain
1058          * of example.com, then we are too low and need to fetch NS. */
1059         size_t i;
1060         /* if we have a DNAME or CNAME we are probably wrong */
1061         /* if we have a qtype DS in the answer section, its fine */
1062         for(i=0; i < msg->rep->an_numrrsets; i++) {
1063                 struct ub_packed_rrset_key* s = msg->rep->rrsets[i];
1064                 if(ntohs(s->rk.type) == LDNS_RR_TYPE_DNAME ||
1065                         ntohs(s->rk.type) == LDNS_RR_TYPE_CNAME) {
1066                         /* not the right answer, maybe too low, check the
1067                          * RRSIG signer name (if there is any) for a hint
1068                          * that it is from the dp zone anyway */
1069                         uint8_t* sname;
1070                         size_t slen;
1071                         val_find_rrset_signer(s, &sname, &slen);
1072                         if(sname && query_dname_compare(dp->name, sname)==0)
1073                                 return 0; /* it is fine, from the right dp */
1074                         return 1;
1075                 }
1076                 if(ntohs(s->rk.type) == LDNS_RR_TYPE_DS)
1077                         return 0; /* fine, we have a DS record */
1078         }
1079         for(i=msg->rep->an_numrrsets;
1080                 i < msg->rep->an_numrrsets + msg->rep->ns_numrrsets; i++) {
1081                 struct ub_packed_rrset_key* s = msg->rep->rrsets[i];
1082                 if(ntohs(s->rk.type) == LDNS_RR_TYPE_SOA) {
1083                         if(dname_subdomain_c(s->rk.dname, msg->qinfo.qname))
1084                                 return 1; /* point is too low */
1085                         if(query_dname_compare(s->rk.dname, dp->name)==0)
1086                                 return 0; /* right dp */
1087                 }
1088                 if(ntohs(s->rk.type) == LDNS_RR_TYPE_NSEC ||
1089                         ntohs(s->rk.type) == LDNS_RR_TYPE_NSEC3) {
1090                         uint8_t* sname;
1091                         size_t slen;
1092                         val_find_rrset_signer(s, &sname, &slen);
1093                         if(sname && query_dname_compare(dp->name, sname)==0)
1094                                 return 0; /* it is fine, from the right dp */
1095                         return 1;
1096                 }
1097         }
1098         /* we do not know */
1099         return 1;
1100 }
1101
1102 int iter_dp_cangodown(struct query_info* qinfo, struct delegpt* dp)
1103 {
1104         /* no delegation point, do not see how we can go down,
1105          * robust check, it should really exist */
1106         if(!dp) return 0;
1107
1108         /* see if dp equals the qname, then we cannot go down further */
1109         if(query_dname_compare(qinfo->qname, dp->name) == 0)
1110                 return 0;
1111         /* if dp is one label above the name we also cannot go down further */
1112         if(dname_count_labels(qinfo->qname) == dp->namelabs+1)
1113                 return 0;
1114         return 1;
1115 }