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_type* 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, time_t prefetch)
 316 {
 317         int got_num = 0, low_rtt = 0, swap_to_front, rtt_band = RTT_BAND;
 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         if(env->cfg->low_rtt_permil != 0 && prefetch == 0 &&
 333                 low_rtt < env->cfg->low_rtt &&
 334                 ub_random_max(env->rnd, 1000) < env->cfg->low_rtt_permil) {
 335                 /* the query is not prefetch, but for a downstream client,
 336                  * there is a low_rtt (fast) server.  We choose that x% of the
 337                  * time */
 338                 /* pick rtt numbers from 0..LOWBAND_RTT */
 339                 rtt_band = env->cfg->low_rtt - low_rtt;
 340         }
 341
 342         got_num = 0;
 343         a = dp->result_list;
 344         while(a) {
 345                 /* skip unsuitable targets */
 346                 if(a->sel_rtt == -1) {
 347                         prev = a;
 348                         a = a->next_result;
 349                         continue;
 350                 }
 351                 /* classify the server address and determine what to do */
 352                 swap_to_front = 0;
 353                 if(a->sel_rtt >= low_rtt && a->sel_rtt - low_rtt <= rtt_band) {
 354                         got_num++;
 355                         swap_to_front = 1;
 356                 } else if(a->sel_rtt<low_rtt && low_rtt-a->sel_rtt<=rtt_band) {
 357                         got_num++;
 358                         swap_to_front = 1;
 359                 }
 360                 /* swap to front if necessary, or move to next result */
 361                 if(swap_to_front && prev) {
 362                         n = a->next_result;
 363                         prev->next_result = n;
 364                         a->next_result = dp->result_list;
 365                         dp->result_list = a;
 366                         a = n;
 367                 } else {
 368                         prev = a;
 369                         a = a->next_result;
 370                 }
 371         }
 372         *selected_rtt = low_rtt;
 373
 374         if (env->cfg->prefer_ip6) {
 375                 int got_num6 = 0;
 376                 int low_rtt6 = 0;
 377                 int i;
 378                 prev = NULL;
 379                 a = dp->result_list;
 380                 for(i = 0; i < got_num; i++) {
 381                         swap_to_front = 0;
 382                         if(a->addr.ss_family == AF_INET6) {
 383                                 got_num6++;
 384                                 swap_to_front = 1;
 385                                 if(low_rtt6 == 0 || a->sel_rtt < low_rtt6) {
 386                                         low_rtt6 = a->sel_rtt;
 387                                 }
 388                         }
 389                         /* swap to front if IPv6, or move to next result */
 390                         if(swap_to_front && prev) {
 391                                 n = a->next_result;
 392                                 prev->next_result = n;
 393                                 a->next_result = dp->result_list;
 394                                 dp->result_list = a;
 395                                 a = n;
 396                         } else {
 397                                 prev = a;
 398                                 a = a->next_result;
 399                         }
 400                 }
 401                 if(got_num6 > 0) {
 402                         got_num = got_num6;
 403                         *selected_rtt = low_rtt6;
 404                 }
 405         }
 406         return got_num;
 407 }
 408
 409 struct delegpt_addr*
 410 iter_server_selection(struct iter_env* iter_env,
 411         struct module_env* env, struct delegpt* dp,
 412         uint8_t* name, size_t namelen, uint16_t qtype, int* dnssec_lame,
 413         int* chase_to_rd, int open_target, struct sock_list* blacklist,
 414         time_t prefetch)
 415 {
 416         int sel;
 417         int selrtt;
 418         struct delegpt_addr* a, *prev;
 419         int num = iter_filter_order(iter_env, env, name, namelen, qtype,
 420                 *env->now, dp, &selrtt, open_target, blacklist, prefetch);
 421
 422         if(num == 0)
 423                 return NULL;
 424         verbose(VERB_ALGO, "selrtt %d", selrtt);
 425         if(selrtt > BLACKLIST_PENALTY) {
 426                 if(selrtt-BLACKLIST_PENALTY > USEFUL_SERVER_TOP_TIMEOUT*3) {
 427                         verbose(VERB_ALGO, "chase to "
 428                                 "blacklisted recursion lame server");
 429                         *chase_to_rd = 1;
 430                 }
 431                 if(selrtt-BLACKLIST_PENALTY > USEFUL_SERVER_TOP_TIMEOUT*2) {
 432                         verbose(VERB_ALGO, "chase to "
 433                                 "blacklisted dnssec lame server");
 434                         *dnssec_lame = 1;
 435                 }
 436         } else {
 437                 if(selrtt > USEFUL_SERVER_TOP_TIMEOUT*3) {
 438                         verbose(VERB_ALGO, "chase to recursion lame server");
 439                         *chase_to_rd = 1;
 440                 }
 441                 if(selrtt > USEFUL_SERVER_TOP_TIMEOUT*2) {
 442                         verbose(VERB_ALGO, "chase to dnssec lame server");
 443                         *dnssec_lame = 1;
 444                 }
 445                 if(selrtt == USEFUL_SERVER_TOP_TIMEOUT) {
 446                         verbose(VERB_ALGO, "chase to blacklisted lame server");
 447                         return NULL;
 448                 }
 449         }
 450
 451         if(num == 1) {
 452                 a = dp->result_list;
 453                 if(++a->attempts < OUTBOUND_MSG_RETRY)
 454                         return a;
 455                 dp->result_list = a->next_result;
 456                 return a;
 457         }
 458
 459         /* randomly select a target from the list */
 460         log_assert(num > 1);
 461         /* grab secure random number, to pick unexpected server.
 462          * also we need it to be threadsafe. */
 463         sel = ub_random_max(env->rnd, num);
 464         a = dp->result_list;
 465         prev = NULL;
 466         while(sel > 0 && a) {
 467                 prev = a;
 468                 a = a->next_result;
 469                 sel--;
 470         }
 471         if(!a)  /* robustness */
 472                 return NULL;
 473         if(++a->attempts < OUTBOUND_MSG_RETRY)
 474                 return a;
 475         /* remove it from the delegation point result list */
 476         if(prev)
 477                 prev->next_result = a->next_result;
 478         else    dp->result_list = a->next_result;
 479         return a;
 480 }
 481
 482 struct dns_msg*
 483 dns_alloc_msg(sldns_buffer* pkt, struct msg_parse* msg,
 484         struct regional* region)
 485 {
 486         struct dns_msg* m = (struct dns_msg*)regional_alloc(region,
 487                 sizeof(struct dns_msg));
 488         if(!m)
 489                 return NULL;
 490         memset(m, 0, sizeof(*m));
 491         if(!parse_create_msg(pkt, msg, NULL, &m->qinfo, &m->rep, region)) {
 492                 log_err("malloc failure: allocating incoming dns_msg");
 493                 return NULL;
 494         }
 495         return m;
 496 }
 497
 498 struct dns_msg*
 499 dns_copy_msg(struct dns_msg* from, struct regional* region)
 500 {
 501         struct dns_msg* m = (struct dns_msg*)regional_alloc(region,
 502                 sizeof(struct dns_msg));
 503         if(!m)
 504                 return NULL;
 505         m->qinfo = from->qinfo;
 506         if(!(m->qinfo.qname = regional_alloc_init(region, from->qinfo.qname,
 507                 from->qinfo.qname_len)))
 508                 return NULL;
 509         if(!(m->rep = reply_info_copy(from->rep, NULL, region)))
 510                 return NULL;
 511         return m;
 512 }
 513
 514 void
 515 iter_dns_store(struct module_env* env, struct query_info* msgqinf,
 516         struct reply_info* msgrep, int is_referral, time_t leeway, int pside,
 517         struct regional* region, uint16_t flags)
 518 {
 519         if(!dns_cache_store(env, msgqinf, msgrep, is_referral, leeway,
 520                 pside, region, flags))
 521                 log_err("out of memory: cannot store data in cache");
 522 }
 523
 524 int
 525 iter_ns_probability(struct ub_randstate* rnd, int n, int m)
 526 {
 527         int sel;
 528         if(n == m) /* 100% chance */
 529                 return 1;
 530         /* we do not need secure random numbers here, but
 531          * we do need it to be threadsafe, so we use this */
 532         sel = ub_random_max(rnd, m);
 533         return (sel < n);
 534 }
 535
 536 /** detect dependency cycle for query and target */
 537 static int
 538 causes_cycle(struct module_qstate* qstate, uint8_t* name, size_t namelen,
 539         uint16_t t, uint16_t c)
 540 {
 541         struct query_info qinf;
 542         qinf.qname = name;
 543         qinf.qname_len = namelen;
 544         qinf.qtype = t;
 545         qinf.qclass = c;
 546         qinf.local_alias = NULL;
 547         fptr_ok(fptr_whitelist_modenv_detect_cycle(
 548                 qstate->env->detect_cycle));
 549         return (*qstate->env->detect_cycle)(qstate, &qinf,
 550                 (uint16_t)(BIT_RD|BIT_CD), qstate->is_priming,
 551                 qstate->is_valrec);
 552 }
 553
 554 void
 555 iter_mark_cycle_targets(struct module_qstate* qstate, struct delegpt* dp)
 556 {
 557         struct delegpt_ns* ns;
 558         for(ns = dp->nslist; ns; ns = ns->next) {
 559                 if(ns->resolved)
 560                         continue;
 561                 /* see if this ns as target causes dependency cycle */
 562                 if(causes_cycle(qstate, ns->name, ns->namelen,
 563                         LDNS_RR_TYPE_AAAA, qstate->qinfo.qclass) ||
 564                    causes_cycle(qstate, ns->name, ns->namelen,
 565                         LDNS_RR_TYPE_A, qstate->qinfo.qclass)) {
 566                         log_nametypeclass(VERB_QUERY, "skipping target due "
 567                                 "to dependency cycle (harden-glue: no may "
 568                                 "fix some of the cycles)",
 569                                 ns->name, LDNS_RR_TYPE_A,
 570                                 qstate->qinfo.qclass);
 571                         ns->resolved = 1;
 572                 }
 573         }
 574 }
 575
 576 void
 577 iter_mark_pside_cycle_targets(struct module_qstate* qstate, struct delegpt* dp)
 578 {
 579         struct delegpt_ns* ns;
 580         for(ns = dp->nslist; ns; ns = ns->next) {
 581                 if(ns->done_pside4 && ns->done_pside6)
 582                         continue;
 583                 /* see if this ns as target causes dependency cycle */
 584                 if(causes_cycle(qstate, ns->name, ns->namelen,
 585                         LDNS_RR_TYPE_A, qstate->qinfo.qclass)) {
 586                         log_nametypeclass(VERB_QUERY, "skipping target due "
 587                                 "to dependency cycle", ns->name,
 588                                 LDNS_RR_TYPE_A, qstate->qinfo.qclass);
 589                         ns->done_pside4 = 1;
 590                 }
 591                 if(causes_cycle(qstate, ns->name, ns->namelen,
 592                         LDNS_RR_TYPE_AAAA, qstate->qinfo.qclass)) {
 593                         log_nametypeclass(VERB_QUERY, "skipping target due "
 594                                 "to dependency cycle", ns->name,
 595                                 LDNS_RR_TYPE_AAAA, qstate->qinfo.qclass);
 596                         ns->done_pside6 = 1;
 597                 }
 598         }
 599 }
 600
 601 int
 602 iter_dp_is_useless(struct query_info* qinfo, uint16_t qflags,
 603         struct delegpt* dp)
 604 {
 605         struct delegpt_ns* ns;
 606         /* check:
 607          *      o RD qflag is on.
 608          *      o no addresses are provided.
 609          *      o all NS items are required glue.
 610          * OR
 611          *      o RD qflag is on.
 612          *      o no addresses are provided.
 613          *      o the query is for one of the nameservers in dp,
 614          *        and that nameserver is a glue-name for this dp.
 615          */
 616         if(!(qflags&BIT_RD))
 617                 return 0;
 618         /* either available or unused targets */
 619         if(dp->usable_list || dp->result_list)
 620                 return 0;
 621
 622         /* see if query is for one of the nameservers, which is glue */
 623         if( (qinfo->qtype == LDNS_RR_TYPE_A ||
 624                 qinfo->qtype == LDNS_RR_TYPE_AAAA) &&
 625                 dname_subdomain_c(qinfo->qname, dp->name) &&
 626                 delegpt_find_ns(dp, qinfo->qname, qinfo->qname_len))
 627                 return 1;
 628
 629         for(ns = dp->nslist; ns; ns = ns->next) {
 630                 if(ns->resolved) /* skip failed targets */
 631                         continue;
 632                 if(!dname_subdomain_c(ns->name, dp->name))
 633                         return 0; /* one address is not required glue */
 634         }
 635         return 1;
 636 }
 637
 638 int
 639 iter_qname_indicates_dnssec(struct module_env* env, struct query_info *qinfo)
 640 {
 641         struct trust_anchor* a;
 642         if(!env || !env->anchors || !qinfo || !qinfo->qname)
 643                 return 0;
 644         /* a trust anchor exists above the name? */
 645         if((a=anchors_lookup(env->anchors, qinfo->qname, qinfo->qname_len,
 646                 qinfo->qclass))) {
 647                 if(a->numDS == 0 && a->numDNSKEY == 0) {
 648                         /* insecure trust point */
 649                         lock_basic_unlock(&a->lock);
 650                         return 0;
 651                 }
 652                 lock_basic_unlock(&a->lock);
 653                 return 1;
 654         }
 655         /* no trust anchor above it. */
 656         return 0;
 657 }
 658
 659 int
 660 iter_indicates_dnssec(struct module_env* env, struct delegpt* dp,
 661         struct dns_msg* msg, uint16_t dclass)
 662 {
 663         struct trust_anchor* a;
 664         /* information not available, !env->anchors can be common */
 665         if(!env || !env->anchors || !dp || !dp->name)
 666                 return 0;
 667         /* a trust anchor exists with this name, RRSIGs expected */
 668         if((a=anchor_find(env->anchors, dp->name, dp->namelabs, dp->namelen,
 669                 dclass))) {
 670                 if(a->numDS == 0 && a->numDNSKEY == 0) {
 671                         /* insecure trust point */
 672                         lock_basic_unlock(&a->lock);
 673                         return 0;
 674                 }
 675                 lock_basic_unlock(&a->lock);
 676                 return 1;
 677         }
 678         /* see if DS rrset was given, in AUTH section */
 679         if(msg && msg->rep &&
 680                 reply_find_rrset_section_ns(msg->rep, dp->name, dp->namelen,
 681                 LDNS_RR_TYPE_DS, dclass))
 682                 return 1;
 683         /* look in key cache */
 684         if(env->key_cache) {
 685                 struct key_entry_key* kk = key_cache_obtain(env->key_cache,
 686                         dp->name, dp->namelen, dclass, env->scratch, *env->now);
 687                 if(kk) {
 688                         if(query_dname_compare(kk->name, dp->name) == 0) {
 689                           if(key_entry_isgood(kk) || key_entry_isbad(kk)) {
 690                                 regional_free_all(env->scratch);
 691                                 return 1;
 692                           } else if(key_entry_isnull(kk)) {
 693                                 regional_free_all(env->scratch);
 694                                 return 0;
 695                           }
 696                         }
 697                         regional_free_all(env->scratch);
 698                 }
 699         }
 700         return 0;
 701 }
 702
 703 int
 704 iter_msg_has_dnssec(struct dns_msg* msg)
 705 {
 706         size_t i;
 707         if(!msg || !msg->rep)
 708                 return 0;
 709         for(i=0; i<msg->rep->an_numrrsets + msg->rep->ns_numrrsets; i++) {
 710                 if(((struct packed_rrset_data*)msg->rep->rrsets[i]->
 711                         entry.data)->rrsig_count > 0)
 712                         return 1;
 713         }
 714         /* empty message has no DNSSEC info, with DNSSEC the reply is
 715          * not empty (NSEC) */
 716         return 0;
 717 }
 718
 719 int iter_msg_from_zone(struct dns_msg* msg, struct delegpt* dp,
 720         enum response_type type, uint16_t dclass)
 721 {
 722         if(!msg || !dp || !msg->rep || !dp->name)
 723                 return 0;
 724         /* SOA RRset - always from reply zone */
 725         if(reply_find_rrset_section_an(msg->rep, dp->name, dp->namelen,
 726                 LDNS_RR_TYPE_SOA, dclass) ||
 727            reply_find_rrset_section_ns(msg->rep, dp->name, dp->namelen,
 728                 LDNS_RR_TYPE_SOA, dclass))
 729                 return 1;
 730         if(type == RESPONSE_TYPE_REFERRAL) {
 731                 size_t i;
 732                 /* if it adds a single label, i.e. we expect .com,
 733                  * and referral to example.com. NS ... , then origin zone
 734                  * is .com. For a referral to sub.example.com. NS ... then
 735                  * we do not know, since example.com. may be in between. */
 736                 for(i=0; i<msg->rep->an_numrrsets+msg->rep->ns_numrrsets;
 737                         i++) {
 738                         struct ub_packed_rrset_key* s = msg->rep->rrsets[i];
 739                         if(ntohs(s->rk.type) == LDNS_RR_TYPE_NS &&
 740                                 ntohs(s->rk.rrset_class) == dclass) {
 741                                 int l = dname_count_labels(s->rk.dname);
 742                                 if(l == dp->namelabs + 1 &&
 743                                         dname_strict_subdomain(s->rk.dname,
 744                                         l, dp->name, dp->namelabs))
 745                                         return 1;
 746                         }
 747                 }
 748                 return 0;
 749         }
 750         log_assert(type==RESPONSE_TYPE_ANSWER || type==RESPONSE_TYPE_CNAME);
 751         /* not a referral, and not lame delegation (upwards), so,
 752          * any NS rrset must be from the zone itself */
 753         if(reply_find_rrset_section_an(msg->rep, dp->name, dp->namelen,
 754                 LDNS_RR_TYPE_NS, dclass) ||
 755            reply_find_rrset_section_ns(msg->rep, dp->name, dp->namelen,
 756                 LDNS_RR_TYPE_NS, dclass))
 757                 return 1;
 758         /* a DNSKEY set is expected at the zone apex as well */
 759         /* this is for 'minimal responses' for DNSKEYs */
 760         if(reply_find_rrset_section_an(msg->rep, dp->name, dp->namelen,
 761                 LDNS_RR_TYPE_DNSKEY, dclass))
 762                 return 1;
 763         return 0;
 764 }
 765
 766 /**
 767  * check equality of two rrsets
 768  * @param k1: rrset
 769  * @param k2: rrset
 770  * @return true if equal
 771  */
 772 static int
 773 rrset_equal(struct ub_packed_rrset_key* k1, struct ub_packed_rrset_key* k2)
 774 {
 775         struct packed_rrset_data* d1 = (struct packed_rrset_data*)
 776                 k1->entry.data;
 777         struct packed_rrset_data* d2 = (struct packed_rrset_data*)
 778                 k2->entry.data;
 779         size_t i, t;
 780         if(k1->rk.dname_len != k2->rk.dname_len ||
 781                 k1->rk.flags != k2->rk.flags ||
 782                 k1->rk.type != k2->rk.type ||
 783                 k1->rk.rrset_class != k2->rk.rrset_class ||
 784                 query_dname_compare(k1->rk.dname, k2->rk.dname) != 0)
 785                 return 0;
 786         if(     /* do not check ttl: d1->ttl != d2->ttl || */
 787                 d1->count != d2->count ||
 788                 d1->rrsig_count != d2->rrsig_count ||
 789                 d1->trust != d2->trust ||
 790                 d1->security != d2->security)
 791                 return 0;
 792         t = d1->count + d1->rrsig_count;
 793         for(i=0; i<t; i++) {
 794                 if(d1->rr_len[i] != d2->rr_len[i] ||
 795                         /* no ttl check: d1->rr_ttl[i] != d2->rr_ttl[i] ||*/
 796                         memcmp(d1->rr_data[i], d2->rr_data[i],
 797                                 d1->rr_len[i]) != 0)
 798                         return 0;
 799         }
 800         return 1;
 801 }
 802
 803 int
 804 reply_equal(struct reply_info* p, struct reply_info* q, struct regional* region)
 805 {
 806         size_t i;
 807         if(p->flags != q->flags ||
 808                 p->qdcount != q->qdcount ||
 809                 /* do not check TTL, this may differ */
 810                 /*
 811                 p->ttl != q->ttl ||
 812                 p->prefetch_ttl != q->prefetch_ttl ||
 813                 */
 814                 p->security != q->security ||
 815                 p->an_numrrsets != q->an_numrrsets ||
 816                 p->ns_numrrsets != q->ns_numrrsets ||
 817                 p->ar_numrrsets != q->ar_numrrsets ||
 818                 p->rrset_count != q->rrset_count)
 819                 return 0;
 820         for(i=0; i<p->rrset_count; i++) {
 821                 if(!rrset_equal(p->rrsets[i], q->rrsets[i])) {
 822                         if(!rrset_canonical_equal(region, p->rrsets[i],
 823                                 q->rrsets[i])) {
 824                                 regional_free_all(region);
 825                                 return 0;
 826                         }
 827                         regional_free_all(region);
 828                 }
 829         }
 830         return 1;
 831 }
 832
 833 void
 834 caps_strip_reply(struct reply_info* rep)
 835 {
 836         size_t i;
 837         if(!rep) return;
 838         /* see if message is a referral, in which case the additional and
 839          * NS record cannot be removed */
 840         /* referrals have the AA flag unset (strict check, not elsewhere in
 841          * unbound, but for 0x20 this is very convenient). */
 842         if(!(rep->flags&BIT_AA))
 843                 return;
 844         /* remove the additional section from the reply */
 845         if(rep->ar_numrrsets != 0) {
 846                 verbose(VERB_ALGO, "caps fallback: removing additional section");
 847                 rep->rrset_count -= rep->ar_numrrsets;
 848                 rep->ar_numrrsets = 0;
 849         }
 850         /* is there an NS set in the authority section to remove? */
 851         /* the failure case (Cisco firewalls) only has one rrset in authsec */
 852         for(i=rep->an_numrrsets; i<rep->an_numrrsets+rep->ns_numrrsets; i++) {
 853                 struct ub_packed_rrset_key* s = rep->rrsets[i];
 854                 if(ntohs(s->rk.type) == LDNS_RR_TYPE_NS) {
 855                         /* remove NS rrset and break from loop (loop limits
 856                          * have changed) */
 857                         /* move last rrset into this position (there is no
 858                          * additional section any more) */
 859                         verbose(VERB_ALGO, "caps fallback: removing NS rrset");
 860                         if(i < rep->rrset_count-1)
 861                                 rep->rrsets[i]=rep->rrsets[rep->rrset_count-1];
 862                         rep->rrset_count --;
 863                         rep->ns_numrrsets --;
 864                         break;
 865                 }
 866         }
 867 }
 868
 869 int caps_failed_rcode(struct reply_info* rep)
 870 {
 871         return !(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR ||
 872                 FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN);
 873 }
 874
 875 void
 876 iter_store_parentside_rrset(struct module_env* env,
 877         struct ub_packed_rrset_key* rrset)
 878 {
 879         struct rrset_ref ref;
 880         rrset = packed_rrset_copy_alloc(rrset, env->alloc, *env->now);
 881         if(!rrset) {
 882                 log_err("malloc failure in store_parentside_rrset");
 883                 return;
 884         }
 885         rrset->rk.flags |= PACKED_RRSET_PARENT_SIDE;
 886         rrset->entry.hash = rrset_key_hash(&rrset->rk);
 887         ref.key = rrset;
 888         ref.id = rrset->id;
 889         /* ignore ret: if it was in the cache, ref updated */
 890         (void)rrset_cache_update(env->rrset_cache, &ref, env->alloc, *env->now);
 891 }
 892
 893 /** fetch NS record from reply, if any */
 894 static struct ub_packed_rrset_key*
 895 reply_get_NS_rrset(struct reply_info* rep)
 896 {
 897         size_t i;
 898         for(i=0; i<rep->rrset_count; i++) {
 899                 if(rep->rrsets[i]->rk.type == htons(LDNS_RR_TYPE_NS)) {
 900                         return rep->rrsets[i];
 901                 }
 902         }
 903         return NULL;
 904 }
 905
 906 void
 907 iter_store_parentside_NS(struct module_env* env, struct reply_info* rep)
 908 {
 909         struct ub_packed_rrset_key* rrset = reply_get_NS_rrset(rep);
 910         if(rrset) {
 911                 log_rrset_key(VERB_ALGO, "store parent-side NS", rrset);
 912                 iter_store_parentside_rrset(env, rrset);
 913         }
 914 }
 915
 916 void iter_store_parentside_neg(struct module_env* env,
 917         struct query_info* qinfo, struct reply_info* rep)
 918 {
 919         /* TTL: NS from referral in iq->deleg_msg,
 920          *      or first RR from iq->response,
 921          *      or servfail5secs if !iq->response */
 922         time_t ttl = NORR_TTL;
 923         struct ub_packed_rrset_key* neg;
 924         struct packed_rrset_data* newd;
 925         if(rep) {
 926                 struct ub_packed_rrset_key* rrset = reply_get_NS_rrset(rep);
 927                 if(!rrset && rep->rrset_count != 0) rrset = rep->rrsets[0];
 928                 if(rrset) ttl = ub_packed_rrset_ttl(rrset);
 929         }
 930         /* create empty rrset to store */
 931         neg = (struct ub_packed_rrset_key*)regional_alloc(env->scratch,
 932                         sizeof(struct ub_packed_rrset_key));
 933         if(!neg) {
 934                 log_err("out of memory in store_parentside_neg");
 935                 return;
 936         }
 937         memset(&neg->entry, 0, sizeof(neg->entry));
 938         neg->entry.key = neg;
 939         neg->rk.type = htons(qinfo->qtype);
 940         neg->rk.rrset_class = htons(qinfo->qclass);
 941         neg->rk.flags = 0;
 942         neg->rk.dname = regional_alloc_init(env->scratch, qinfo->qname,
 943                 qinfo->qname_len);
 944         if(!neg->rk.dname) {
 945                 log_err("out of memory in store_parentside_neg");
 946                 return;
 947         }
 948         neg->rk.dname_len = qinfo->qname_len;
 949         neg->entry.hash = rrset_key_hash(&neg->rk);
 950         newd = (struct packed_rrset_data*)regional_alloc_zero(env->scratch,
 951                 sizeof(struct packed_rrset_data) + sizeof(size_t) +
 952                 sizeof(uint8_t*) + sizeof(time_t) + sizeof(uint16_t));
 953         if(!newd) {
 954                 log_err("out of memory in store_parentside_neg");
 955                 return;
 956         }
 957         neg->entry.data = newd;
 958         newd->ttl = ttl;
 959         /* entry must have one RR, otherwise not valid in cache.
 960          * put in one RR with empty rdata: those are ignored as nameserver */
 961         newd->count = 1;
 962         newd->rrsig_count = 0;
 963         newd->trust = rrset_trust_ans_noAA;
 964         newd->rr_len = (size_t*)((uint8_t*)newd +
 965                 sizeof(struct packed_rrset_data));
 966         newd->rr_len[0] = 0 /* zero len rdata */ + sizeof(uint16_t);
 967         packed_rrset_ptr_fixup(newd);
 968         newd->rr_ttl[0] = newd->ttl;
 969         sldns_write_uint16(newd->rr_data[0], 0 /* zero len rdata */);
 970         /* store it */
 971         log_rrset_key(VERB_ALGO, "store parent-side negative", neg);
 972         iter_store_parentside_rrset(env, neg);
 973 }
 974
 975 int
 976 iter_lookup_parent_NS_from_cache(struct module_env* env, struct delegpt* dp,
 977         struct regional* region, struct query_info* qinfo)
 978 {
 979         struct ub_packed_rrset_key* akey;
 980         akey = rrset_cache_lookup(env->rrset_cache, dp->name,
 981                 dp->namelen, LDNS_RR_TYPE_NS, qinfo->qclass,
 982                 PACKED_RRSET_PARENT_SIDE, *env->now, 0);
 983         if(akey) {
 984                 log_rrset_key(VERB_ALGO, "found parent-side NS in cache", akey);
 985                 dp->has_parent_side_NS = 1;
 986                 /* and mark the new names as lame */
 987                 if(!delegpt_rrset_add_ns(dp, region, akey, 1)) {
 988                         lock_rw_unlock(&akey->entry.lock);
 989                         return 0;
 990                 }
 991                 lock_rw_unlock(&akey->entry.lock);
 992         }
 993         return 1;
 994 }
 995
 996 int iter_lookup_parent_glue_from_cache(struct module_env* env,
 997         struct delegpt* dp, struct regional* region, struct query_info* qinfo)
 998 {
 999         struct ub_packed_rrset_key* akey;
1000         struct delegpt_ns* ns;
1001         size_t num = delegpt_count_targets(dp);
1002         for(ns = dp->nslist; ns; ns = ns->next) {
1003                 /* get cached parentside A */
1004                 akey = rrset_cache_lookup(env->rrset_cache, ns->name,
1005                         ns->namelen, LDNS_RR_TYPE_A, qinfo->qclass,
1006                         PACKED_RRSET_PARENT_SIDE, *env->now, 0);
1007                 if(akey) {
1008                         log_rrset_key(VERB_ALGO, "found parent-side", akey);
1009                         ns->done_pside4 = 1;
1010                         /* a negative-cache-element has no addresses it adds */
1011                         if(!delegpt_add_rrset_A(dp, region, akey, 1))
1012                                 log_err("malloc failure in lookup_parent_glue");
1013                         lock_rw_unlock(&akey->entry.lock);
1014                 }
1015                 /* get cached parentside AAAA */
1016                 akey = rrset_cache_lookup(env->rrset_cache, ns->name,
1017                         ns->namelen, LDNS_RR_TYPE_AAAA, qinfo->qclass,
1018                         PACKED_RRSET_PARENT_SIDE, *env->now, 0);
1019                 if(akey) {
1020                         log_rrset_key(VERB_ALGO, "found parent-side", akey);
1021                         ns->done_pside6 = 1;
1022                         /* a negative-cache-element has no addresses it adds */
1023                         if(!delegpt_add_rrset_AAAA(dp, region, akey, 1))
1024                                 log_err("malloc failure in lookup_parent_glue");
1025                         lock_rw_unlock(&akey->entry.lock);
1026                 }
1027         }
1028         /* see if new (but lame) addresses have become available */
1029         return delegpt_count_targets(dp) != num;
1030 }
1031
1032 int
1033 iter_get_next_root(struct iter_hints* hints, struct iter_forwards* fwd,
1034         uint16_t* c)
1035 {
1036         uint16_t c1 = *c, c2 = *c;
1037         int r1 = hints_next_root(hints, &c1);
1038         int r2 = forwards_next_root(fwd, &c2);
1039         if(!r1 && !r2) /* got none, end of list */
1040                 return 0;
1041         else if(!r1) /* got one, return that */
1042                 *c = c2;
1043         else if(!r2)
1044                 *c = c1;
1045         else if(c1 < c2) /* got both take smallest */
1046                 *c = c1;
1047         else    *c = c2;
1048         return 1;
1049 }
1050
1051 void
1052 iter_scrub_ds(struct dns_msg* msg, struct ub_packed_rrset_key* ns, uint8_t* z)
1053 {
1054         /* Only the DS record for the delegation itself is expected.
1055          * We allow DS for everything between the bailiwick and the
1056          * zonecut, thus DS records must be at or above the zonecut.
1057          * And the DS records must be below the server authority zone.
1058          * The answer section is already scrubbed. */
1059         size_t i = msg->rep->an_numrrsets;
1060         while(i < (msg->rep->an_numrrsets + msg->rep->ns_numrrsets)) {
1061                 struct ub_packed_rrset_key* s = msg->rep->rrsets[i];
1062                 if(ntohs(s->rk.type) == LDNS_RR_TYPE_DS &&
1063                         (!ns || !dname_subdomain_c(ns->rk.dname, s->rk.dname)
1064                         || query_dname_compare(z, s->rk.dname) == 0)) {
1065                         log_nametypeclass(VERB_ALGO, "removing irrelevant DS",
1066                                 s->rk.dname, ntohs(s->rk.type),
1067                                 ntohs(s->rk.rrset_class));
1068                         memmove(msg->rep->rrsets+i, msg->rep->rrsets+i+1,
1069                                 sizeof(struct ub_packed_rrset_key*) *
1070                                 (msg->rep->rrset_count-i-1));
1071                         msg->rep->ns_numrrsets--;
1072                         msg->rep->rrset_count--;
1073                         /* stay at same i, but new record */
1074                         continue;
1075                 }
1076                 i++;
1077         }
1078 }
1079
1080 void iter_dec_attempts(struct delegpt* dp, int d)
1081 {
1082         struct delegpt_addr* a;
1083         for(a=dp->target_list; a; a = a->next_target) {
1084                 if(a->attempts >= OUTBOUND_MSG_RETRY) {
1085                         /* add back to result list */
1086                         a->next_result = dp->result_list;
1087                         dp->result_list = a;
1088                 }
1089                 if(a->attempts > d)
1090                         a->attempts -= d;
1091                 else a->attempts = 0;
1092         }
1093 }
1094
1095 void iter_merge_retry_counts(struct delegpt* dp, struct delegpt* old)
1096 {
1097         struct delegpt_addr* a, *o, *prev;
1098         for(a=dp->target_list; a; a = a->next_target) {
1099                 o = delegpt_find_addr(old, &a->addr, a->addrlen);
1100                 if(o) {
1101                         log_addr(VERB_ALGO, "copy attempt count previous dp",
1102                                 &a->addr, a->addrlen);
1103                         a->attempts = o->attempts;
1104                 }
1105         }
1106         prev = NULL;
1107         a = dp->usable_list;
1108         while(a) {
1109                 if(a->attempts >= OUTBOUND_MSG_RETRY) {
1110                         log_addr(VERB_ALGO, "remove from usable list dp",
1111                                 &a->addr, a->addrlen);
1112                         /* remove from result list */
1113                         if(prev)
1114                                 prev->next_usable = a->next_usable;
1115                         else    dp->usable_list = a->next_usable;
1116                         /* prev stays the same */
1117                         a = a->next_usable;
1118                         continue;
1119                 }
1120                 prev = a;
1121                 a = a->next_usable;
1122         }
1123 }
1124
1125 int
1126 iter_ds_toolow(struct dns_msg* msg, struct delegpt* dp)
1127 {
1128         /* if for query example.com, there is example.com SOA or a subdomain
1129          * of example.com, then we are too low and need to fetch NS. */
1130         size_t i;
1131         /* if we have a DNAME or CNAME we are probably wrong */
1132         /* if we have a qtype DS in the answer section, its fine */
1133         for(i=0; i < msg->rep->an_numrrsets; i++) {
1134                 struct ub_packed_rrset_key* s = msg->rep->rrsets[i];
1135                 if(ntohs(s->rk.type) == LDNS_RR_TYPE_DNAME ||
1136                         ntohs(s->rk.type) == LDNS_RR_TYPE_CNAME) {
1137                         /* not the right answer, maybe too low, check the
1138                          * RRSIG signer name (if there is any) for a hint
1139                          * that it is from the dp zone anyway */
1140                         uint8_t* sname;
1141                         size_t slen;
1142                         val_find_rrset_signer(s, &sname, &slen);
1143                         if(sname && query_dname_compare(dp->name, sname)==0)
1144                                 return 0; /* it is fine, from the right dp */
1145                         return 1;
1146                 }
1147                 if(ntohs(s->rk.type) == LDNS_RR_TYPE_DS)
1148                         return 0; /* fine, we have a DS record */
1149         }
1150         for(i=msg->rep->an_numrrsets;
1151                 i < msg->rep->an_numrrsets + msg->rep->ns_numrrsets; i++) {
1152                 struct ub_packed_rrset_key* s = msg->rep->rrsets[i];
1153                 if(ntohs(s->rk.type) == LDNS_RR_TYPE_SOA) {
1154                         if(dname_subdomain_c(s->rk.dname, msg->qinfo.qname))
1155                                 return 1; /* point is too low */
1156                         if(query_dname_compare(s->rk.dname, dp->name)==0)
1157                                 return 0; /* right dp */
1158                 }
1159                 if(ntohs(s->rk.type) == LDNS_RR_TYPE_NSEC ||
1160                         ntohs(s->rk.type) == LDNS_RR_TYPE_NSEC3) {
1161                         uint8_t* sname;
1162                         size_t slen;
1163                         val_find_rrset_signer(s, &sname, &slen);
1164                         if(sname && query_dname_compare(dp->name, sname)==0)
1165                                 return 0; /* it is fine, from the right dp */
1166                         return 1;
1167                 }
1168         }
1169         /* we do not know */
1170         return 1;
1171 }
1172
1173 int iter_dp_cangodown(struct query_info* qinfo, struct delegpt* dp)
1174 {
1175         /* no delegation point, do not see how we can go down,
1176          * robust check, it should really exist */
1177         if(!dp) return 0;
1178
1179         /* see if dp equals the qname, then we cannot go down further */
1180         if(query_dname_compare(qinfo->qname, dp->name) == 0)
1181                 return 0;
1182         /* if dp is one label above the name we also cannot go down further */
1183         if(dname_count_labels(qinfo->qname) == dp->namelabs+1)
1184                 return 0;
1185         return 1;
1186 }