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https://github.com/NLnetLabs/unbound.git
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fe33f7c72c
git-svn-id: file:///svn/unbound/trunk@682 be551aaa-1e26-0410-a405-d3ace91eadb9
365 lines
10 KiB
C
365 lines
10 KiB
C
/*
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* iterator/iter_utils.c - iterative resolver module utility functions.
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*
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* Copyright (c) 2007, NLnet Labs. All rights reserved.
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*
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* This software is open source.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of the NLNET LABS nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* \file
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*
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* This file contains functions to assist the iterator module.
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* Configuration options. Forward zones.
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*/
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#include "config.h"
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#include "iterator/iter_utils.h"
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#include "iterator/iterator.h"
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#include "iterator/iter_hints.h"
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#include "iterator/iter_fwd.h"
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#include "iterator/iter_donotq.h"
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#include "iterator/iter_delegpt.h"
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#include "services/cache/infra.h"
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#include "services/cache/dns.h"
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#include "services/cache/rrset.h"
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#include "util/net_help.h"
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#include "util/module.h"
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#include "util/log.h"
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#include "util/config_file.h"
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#include "util/region-allocator.h"
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#include "util/data/msgparse.h"
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#include "util/data/dname.h"
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#include "util/random.h"
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#include "util/fptr_wlist.h"
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/** fillup fetch policy array */
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static void
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fetch_fill(struct iter_env* ie, const char* str)
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{
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char* s = (char*)str, *e;
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int i;
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for(i=0; i<ie->max_dependency_depth+1; i++) {
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ie->target_fetch_policy[i] = strtol(s, &e, 10);
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if(s == e)
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fatal_exit("cannot parse fetch policy number %s", s);
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s = e;
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}
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}
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/** Read config string that represents the target fetch policy */
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static int
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read_fetch_policy(struct iter_env* ie, const char* str)
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{
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int count = cfg_count_numbers(str);
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if(count < 1) {
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log_err("Cannot parse target fetch policy: \"%s\"", str);
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return 0;
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}
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ie->max_dependency_depth = count - 1;
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ie->target_fetch_policy = (int*)calloc(
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(size_t)ie->max_dependency_depth+1, sizeof(int));
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if(!ie->target_fetch_policy) {
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log_err("alloc fetch policy: out of memory");
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return 0;
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}
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fetch_fill(ie, str);
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return 1;
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}
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int
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iter_apply_cfg(struct iter_env* iter_env, struct config_file* cfg)
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{
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int i;
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/* target fetch policy */
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if(!read_fetch_policy(iter_env, cfg->target_fetch_policy))
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return 0;
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for(i=0; i<iter_env->max_dependency_depth+1; i++)
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verbose(VERB_DETAIL, "target fetch policy for level %d is %d",
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i, iter_env->target_fetch_policy[i]);
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if(!iter_env->hints)
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iter_env->hints = hints_create();
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if(!iter_env->hints || !hints_apply_cfg(iter_env->hints, cfg)) {
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log_err("Could not set root or stub hints");
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return 0;
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}
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if(!iter_env->fwds)
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iter_env->fwds = forwards_create();
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if(!iter_env->fwds || !forwards_apply_cfg(iter_env->fwds, cfg)) {
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log_err("Could not set forward zones");
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return 0;
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}
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if(!iter_env->donotq)
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iter_env->donotq = donotq_create();
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if(!iter_env->donotq || !donotq_apply_cfg(iter_env->donotq, cfg)) {
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log_err("Could not set donotqueryaddresses");
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return 0;
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}
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iter_env->supports_ipv6 = cfg->do_ip6;
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return 1;
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}
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/** filter out unsuitable targets, return rtt or -1 */
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static int
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iter_filter_unsuitable(struct iter_env* iter_env, struct module_env* env,
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uint8_t* name, size_t namelen, time_t now, struct delegpt_addr* a)
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{
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int rtt;
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int lame;
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if(donotq_lookup(iter_env->donotq, &a->addr, a->addrlen)) {
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return -1; /* server is on the donotquery list */
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}
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if(!iter_env->supports_ipv6 && addr_is_ip6(&a->addr, a->addrlen)) {
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return -1; /* there is no ip6 available */
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}
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/* check lameness - need zone , class info */
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if(infra_get_lame_rtt(env->infra_cache, &a->addr, a->addrlen,
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name, namelen, &lame, &rtt, now)) {
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if(lame)
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return -1; /* server is lame */
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else if(rtt >= USEFUL_SERVER_TOP_TIMEOUT)
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return -1; /* server is unresponsive */
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else return rtt;
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}
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/* no server information present */
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return UNKNOWN_SERVER_NICENESS;
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}
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/** filter the addres list, putting best targets at front,
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* returns number of best targets (or 0, no suitable targets) */
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static int
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iter_filter_order(struct iter_env* iter_env, struct module_env* env,
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uint8_t* name, size_t namelen, time_t now, struct delegpt* dp)
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{
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int got_num = 0, got_rtt = 0, thisrtt, swap_to_front;
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struct delegpt_addr* a, *n, *prev=NULL;
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a = dp->result_list;
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while(a) {
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/* filter out unsuitable targets */
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thisrtt = iter_filter_unsuitable(iter_env, env, name, namelen,
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now, a);
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if(thisrtt == -1) {
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prev = a;
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a = a->next_result;
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continue;
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}
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/* classify the server address and determine what to do */
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swap_to_front = 0;
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if(got_num == 0) {
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got_rtt = thisrtt;
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got_num = 1;
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swap_to_front = 1;
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} else if(thisrtt == got_rtt) {
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got_num++;
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swap_to_front = 1;
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} else if(thisrtt < got_rtt) {
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got_rtt = thisrtt;
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got_num = 1; /* start back at count of 1 */
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swap_to_front = 1;
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}
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/* swap to front if necessary, or move to next result */
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if(swap_to_front && prev) {
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n = a->next_result;
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prev->next_result = n;
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a->next_result = dp->result_list;
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dp->result_list = a;
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a = n;
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} else {
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prev = a;
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a = a->next_result;
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}
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}
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return got_num;
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}
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struct delegpt_addr*
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iter_server_selection(struct iter_env* iter_env,
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struct module_env* env, struct delegpt* dp,
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uint8_t* name, size_t namelen)
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{
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time_t now = time(NULL);
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int sel;
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struct delegpt_addr* a, *prev;
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int num = iter_filter_order(iter_env, env, name, namelen, now, dp);
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if(num == 0)
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return NULL;
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if(num == 1) {
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a = dp->result_list;
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dp->result_list = a->next_result;
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return a;
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}
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/* randomly select a target from the list */
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log_assert(num > 1);
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/* we do not need secure random numbers here, but
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* we do need it to be threadsafe, so we use this */
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sel = ub_random(env->rnd) % num;
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a = dp->result_list;
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prev = NULL;
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while(sel > 0 && a) {
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prev = a;
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a = a->next_result;
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sel--;
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}
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if(!a) /* robustness */
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return NULL;
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/* remove it from the delegation point result list */
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if(prev)
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prev->next_result = a->next_result;
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else dp->result_list = a->next_result;
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return a;
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}
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struct dns_msg*
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dns_alloc_msg(ldns_buffer* pkt, struct msg_parse* msg, struct region* region)
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{
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struct dns_msg* m = (struct dns_msg*)region_alloc(region,
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sizeof(struct dns_msg));
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if(!m)
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return NULL;
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memset(m, 0, sizeof(*m));
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if(!parse_create_msg(pkt, msg, NULL, &m->qinfo, &m->rep, region)) {
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log_err("malloc failure: allocating incoming dns_msg");
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return NULL;
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}
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return m;
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}
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struct dns_msg*
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dns_copy_msg(struct dns_msg* from, struct region* region)
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{
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struct dns_msg* m = (struct dns_msg*)region_alloc(region,
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sizeof(struct dns_msg));
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if(!m)
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return NULL;
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m->qinfo = from->qinfo;
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if(!(m->qinfo.qname = region_alloc_init(region, from->qinfo.qname,
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from->qinfo.qname_len)))
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return NULL;
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if(!(m->rep = reply_info_copy(from->rep, NULL, region)))
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return NULL;
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return m;
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}
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int
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iter_dns_store(struct module_env* env, struct query_info* msgqinf,
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struct reply_info* msgrep, int is_referral)
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{
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return dns_cache_store(env, msgqinf, msgrep, is_referral);
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}
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int
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iter_ns_probability(struct ub_randstate* rnd, int n, int m)
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{
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int sel;
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if(n == m) /* 100% chance */
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return 1;
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/* we do not need secure random numbers here, but
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* we do need it to be threadsafe, so we use this */
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sel = ub_random(rnd) % m;
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return (sel < n);
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}
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/** detect dependency cycle for query and target */
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static int
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causes_cycle(struct module_qstate* qstate, uint8_t* name, size_t namelen,
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uint16_t t, uint16_t c)
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{
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struct query_info qinf;
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qinf.qname = name;
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qinf.qname_len = namelen;
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qinf.qtype = t;
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qinf.qclass = c;
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log_assert(fptr_whitelist_modenv_detect_cycle(
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qstate->env->detect_cycle));
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return (*qstate->env->detect_cycle)(qstate, &qinf,
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(uint16_t)(BIT_RD|BIT_CD), qstate->is_priming);
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}
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void
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iter_mark_cycle_targets(struct module_qstate* qstate, struct delegpt* dp)
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{
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struct delegpt_ns* ns;
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for(ns = dp->nslist; ns; ns = ns->next) {
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if(ns->resolved)
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continue;
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/* see if this ns as target causes dependency cycle */
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if(causes_cycle(qstate, ns->name, ns->namelen,
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LDNS_RR_TYPE_AAAA, qstate->qinfo.qclass) ||
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causes_cycle(qstate, ns->name, ns->namelen,
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LDNS_RR_TYPE_A, qstate->qinfo.qclass)) {
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log_nametypeclass(VERB_DETAIL, "skipping target due "
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"to dependency cycle (harden-glue: no may "
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"fix some of the cycles)",
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ns->name, LDNS_RR_TYPE_A,
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qstate->qinfo.qclass);
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ns->resolved = 1;
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}
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}
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}
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int
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iter_dp_is_useless(struct module_qstate* qstate, struct delegpt* dp)
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{
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struct delegpt_ns* ns;
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/* check:
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* o all NS items are required glue.
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* o no addresses are provided.
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* o RD qflag is on.
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* OR
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* o no addresses are provided.
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* o RD qflag is on.
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* o the query is for one of the nameservers in dp,
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* and that nameserver is a glue-name for this dp.
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*/
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if(!(qstate->query_flags&BIT_RD))
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return 0;
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/* either available or unused targets */
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if(dp->usable_list || dp->result_list)
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return 0;
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/* see if query is for one of the nameservers, which is glue */
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if( (qstate->qinfo.qtype == LDNS_RR_TYPE_A ||
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qstate->qinfo.qtype == LDNS_RR_TYPE_AAAA) &&
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dname_subdomain_c(qstate->qinfo.qname, dp->name) &&
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delegpt_find_ns(dp, qstate->qinfo.qname,
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qstate->qinfo.qname_len))
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return 1;
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for(ns = dp->nslist; ns; ns = ns->next) {
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if(ns->resolved) /* skip failed targets */
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continue;
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if(!dname_subdomain_c(ns->name, dp->name))
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return 0; /* one address is not required glue */
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}
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return 1;
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}
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