[apple/network_cmds.git] / unbound / iterator / iterator.c

/*
 * iterator/iterator.c - iterative resolver DNS query response module
 *
 * Copyright (c) 2007, NLnet Labs. All rights reserved.
 *
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * \file
 *
 * This file contains a module that performs recusive iterative DNS query
 * processing.
 */

#include "config.h"
#include "iterator/iterator.h"
#include "iterator/iter_utils.h"
#include "iterator/iter_hints.h"
#include "iterator/iter_fwd.h"
#include "iterator/iter_donotq.h"
#include "iterator/iter_delegpt.h"
#include "iterator/iter_resptype.h"
#include "iterator/iter_scrub.h"
#include "iterator/iter_priv.h"
#include "validator/val_neg.h"
#include "services/cache/dns.h"
#include "services/cache/infra.h"
#include "util/module.h"
#include "util/netevent.h"
#include "util/net_help.h"
#include "util/regional.h"
#include "util/data/dname.h"
#include "util/data/msgencode.h"
#include "util/fptr_wlist.h"
#include "util/config_file.h"
#include "ldns/rrdef.h"
#include "ldns/wire2str.h"
#include "ldns/parseutil.h"
#include "ldns/sbuffer.h"

int 
iter_init(struct module_env* env, int id)
{
        struct iter_env* iter_env = (struct iter_env*)calloc(1,
                sizeof(struct iter_env));
        if(!iter_env) {
                log_err("malloc failure");
                return 0;
        }
        env->modinfo[id] = (void*)iter_env;
        if(!iter_apply_cfg(iter_env, env->cfg)) {
                log_err("iterator: could not apply configuration settings.");
                return 0;
        }
        return 1;
}

void 
iter_deinit(struct module_env* env, int id)
{
        struct iter_env* iter_env;
        if(!env || !env->modinfo[id])
                return;
        iter_env = (struct iter_env*)env->modinfo[id];
        free(iter_env->target_fetch_policy);
        priv_delete(iter_env->priv);
        donotq_delete(iter_env->donotq);
        free(iter_env);
        env->modinfo[id] = NULL;
}

/** new query for iterator */
static int
iter_new(struct module_qstate* qstate, int id)
{
        struct iter_qstate* iq = (struct iter_qstate*)regional_alloc(
                qstate->region, sizeof(struct iter_qstate));
        qstate->minfo[id] = iq;
        if(!iq) 
                return 0;
        memset(iq, 0, sizeof(*iq));
        iq->state = INIT_REQUEST_STATE;
        iq->final_state = FINISHED_STATE;
        iq->an_prepend_list = NULL;
        iq->an_prepend_last = NULL;
        iq->ns_prepend_list = NULL;
        iq->ns_prepend_last = NULL;
        iq->dp = NULL;
        iq->depth = 0;
        iq->num_target_queries = 0;
        iq->num_current_queries = 0;
        iq->query_restart_count = 0;
        iq->referral_count = 0;
        iq->sent_count = 0;
        iq->target_count = NULL;
        iq->wait_priming_stub = 0;
        iq->refetch_glue = 0;
        iq->dnssec_expected = 0;
        iq->dnssec_lame_query = 0;
        iq->chase_flags = qstate->query_flags;
        /* Start with the (current) qname. */
        iq->qchase = qstate->qinfo;
        outbound_list_init(&iq->outlist);
        return 1;
}

/**
 * Transition to the next state. This can be used to advance a currently
 * processing event. It cannot be used to reactivate a forEvent.
 *
 * @param iq: iterator query state
 * @param nextstate The state to transition to.
 * @return true. This is so this can be called as the return value for the
 *         actual process*State() methods. (Transitioning to the next state
 *         implies further processing).
 */
static int
next_state(struct iter_qstate* iq, enum iter_state nextstate)
{
        /* If transitioning to a "response" state, make sure that there is a
         * response */
        if(iter_state_is_responsestate(nextstate)) {
                if(iq->response == NULL) {
                        log_err("transitioning to response state sans "
                                "response.");
                }
        }
        iq->state = nextstate;
        return 1;
}

/**
 * Transition an event to its final state. Final states always either return
 * a result up the module chain, or reactivate a dependent event. Which
 * final state to transtion to is set in the module state for the event when
 * it was created, and depends on the original purpose of the event.
 *
 * The response is stored in the qstate->buf buffer.
 *
 * @param iq: iterator query state
 * @return false. This is so this method can be used as the return value for
 *         the processState methods. (Transitioning to the final state
 */
static int
final_state(struct iter_qstate* iq)
{
        return next_state(iq, iq->final_state);
}

/**
 * Callback routine to handle errors in parent query states
 * @param qstate: query state that failed.
 * @param id: module id.
 * @param super: super state.
 */
static void
error_supers(struct module_qstate* qstate, int id, struct module_qstate* super)
{
        struct iter_qstate* super_iq = (struct iter_qstate*)super->minfo[id];

        if(qstate->qinfo.qtype == LDNS_RR_TYPE_A ||
                qstate->qinfo.qtype == LDNS_RR_TYPE_AAAA) {
                /* mark address as failed. */
                struct delegpt_ns* dpns = NULL;
                if(super_iq->dp)
                        dpns = delegpt_find_ns(super_iq->dp, 
                                qstate->qinfo.qname, qstate->qinfo.qname_len);
                if(!dpns) {
                        /* not interested */
                        verbose(VERB_ALGO, "subq error, but not interested");
                        log_query_info(VERB_ALGO, "superq", &super->qinfo);
                        if(super_iq->dp)
                                delegpt_log(VERB_ALGO, super_iq->dp);
                        log_assert(0);
                        return;
                } else {
                        /* see if the failure did get (parent-lame) info */
                        if(!cache_fill_missing(super->env, 
                                super_iq->qchase.qclass, super->region, 
                                super_iq->dp))
                                log_err("out of memory adding missing");
                }
                dpns->resolved = 1; /* mark as failed */
                super_iq->num_target_queries--; 
        }
        if(qstate->qinfo.qtype == LDNS_RR_TYPE_NS) {
                /* prime failed to get delegation */
                super_iq->dp = NULL;
        }
        /* evaluate targets again */
        super_iq->state = QUERYTARGETS_STATE; 
        /* super becomes runnable, and will process this change */
}

/**
 * Return an error to the client
 * @param qstate: our query state
 * @param id: module id
 * @param rcode: error code (DNS errcode).
 * @return: 0 for use by caller, to make notation easy, like:
 *      return error_response(..). 
 */
static int
error_response(struct module_qstate* qstate, int id, int rcode)
{
        verbose(VERB_QUERY, "return error response %s", 
                sldns_lookup_by_id(sldns_rcodes, rcode)?
                sldns_lookup_by_id(sldns_rcodes, rcode)->name:"??");
        qstate->return_rcode = rcode;
        qstate->return_msg = NULL;
        qstate->ext_state[id] = module_finished;
        return 0;
}

/**
 * Return an error to the client and cache the error code in the
 * message cache (so per qname, qtype, qclass).
 * @param qstate: our query state
 * @param id: module id
 * @param rcode: error code (DNS errcode).
 * @return: 0 for use by caller, to make notation easy, like:
 *      return error_response(..). 
 */
static int
error_response_cache(struct module_qstate* qstate, int id, int rcode)
{
        /* store in cache */
        struct reply_info err;
        if(qstate->prefetch_leeway > NORR_TTL) {
                verbose(VERB_ALGO, "error response for prefetch in cache");
                /* attempt to adjust the cache entry prefetch */
                if(dns_cache_prefetch_adjust(qstate->env, &qstate->qinfo,
                        NORR_TTL, qstate->query_flags))
                        return error_response(qstate, id, rcode);
                /* if that fails (not in cache), fall through to store err */
        }
        memset(&err, 0, sizeof(err));
        err.flags = (uint16_t)(BIT_QR | BIT_RA);
        FLAGS_SET_RCODE(err.flags, rcode);
        err.qdcount = 1;
        err.ttl = NORR_TTL;
        err.prefetch_ttl = PREFETCH_TTL_CALC(err.ttl);
        /* do not waste time trying to validate this servfail */
        err.security = sec_status_indeterminate;
        verbose(VERB_ALGO, "store error response in message cache");
        iter_dns_store(qstate->env, &qstate->qinfo, &err, 0, 0, 0, NULL,
                qstate->query_flags);
        return error_response(qstate, id, rcode);
}

/** check if prepend item is duplicate item */
static int
prepend_is_duplicate(struct ub_packed_rrset_key** sets, size_t to,
        struct ub_packed_rrset_key* dup)
{
        size_t i;
        for(i=0; i<to; i++) {
                if(sets[i]->rk.type == dup->rk.type &&
                        sets[i]->rk.rrset_class == dup->rk.rrset_class &&
                        sets[i]->rk.dname_len == dup->rk.dname_len &&
                        query_dname_compare(sets[i]->rk.dname, dup->rk.dname)
                        == 0)
                        return 1;
        }
        return 0;
}

/** prepend the prepend list in the answer and authority section of dns_msg */
static int
iter_prepend(struct iter_qstate* iq, struct dns_msg* msg, 
        struct regional* region)
{
        struct iter_prep_list* p;
        struct ub_packed_rrset_key** sets;
        size_t num_an = 0, num_ns = 0;;
        for(p = iq->an_prepend_list; p; p = p->next)
                num_an++;
        for(p = iq->ns_prepend_list; p; p = p->next)
                num_ns++;
        if(num_an + num_ns == 0)
                return 1;
        verbose(VERB_ALGO, "prepending %d rrsets", (int)num_an + (int)num_ns);
        sets = regional_alloc(region, (num_an+num_ns+msg->rep->rrset_count) *
                sizeof(struct ub_packed_rrset_key*));
        if(!sets) 
                return 0;
        /* ANSWER section */
        num_an = 0;
        for(p = iq->an_prepend_list; p; p = p->next) {
                sets[num_an++] = p->rrset;
        }
        memcpy(sets+num_an, msg->rep->rrsets, msg->rep->an_numrrsets *
                sizeof(struct ub_packed_rrset_key*));
        /* AUTH section */
        num_ns = 0;
        for(p = iq->ns_prepend_list; p; p = p->next) {
                if(prepend_is_duplicate(sets+msg->rep->an_numrrsets+num_an,
                        num_ns, p->rrset) || prepend_is_duplicate(
                        msg->rep->rrsets+msg->rep->an_numrrsets, 
                        msg->rep->ns_numrrsets, p->rrset))
                        continue;
                sets[msg->rep->an_numrrsets + num_an + num_ns++] = p->rrset;
        }
        memcpy(sets + num_an + msg->rep->an_numrrsets + num_ns, 
                msg->rep->rrsets + msg->rep->an_numrrsets, 
                (msg->rep->ns_numrrsets + msg->rep->ar_numrrsets) *
                sizeof(struct ub_packed_rrset_key*));

        /* NXDOMAIN rcode can stay if we prepended DNAME/CNAMEs, because
         * this is what recursors should give. */
        msg->rep->rrset_count += num_an + num_ns;
        msg->rep->an_numrrsets += num_an;
        msg->rep->ns_numrrsets += num_ns;
        msg->rep->rrsets = sets;
        return 1;
}

/**
 * Add rrset to ANSWER prepend list
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param rrset: rrset to add.
 * @return false on failure (malloc).
 */
static int
iter_add_prepend_answer(struct module_qstate* qstate, struct iter_qstate* iq,
        struct ub_packed_rrset_key* rrset)
{
        struct iter_prep_list* p = (struct iter_prep_list*)regional_alloc(
                qstate->region, sizeof(struct iter_prep_list));
        if(!p)
                return 0;
        p->rrset = rrset;
        p->next = NULL;
        /* add at end */
        if(iq->an_prepend_last)
                iq->an_prepend_last->next = p;
        else    iq->an_prepend_list = p;
        iq->an_prepend_last = p;
        return 1;
}

/**
 * Add rrset to AUTHORITY prepend list
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param rrset: rrset to add.
 * @return false on failure (malloc).
 */
static int
iter_add_prepend_auth(struct module_qstate* qstate, struct iter_qstate* iq,
        struct ub_packed_rrset_key* rrset)
{
        struct iter_prep_list* p = (struct iter_prep_list*)regional_alloc(
                qstate->region, sizeof(struct iter_prep_list));
        if(!p)
                return 0;
        p->rrset = rrset;
        p->next = NULL;
        /* add at end */
        if(iq->ns_prepend_last)
                iq->ns_prepend_last->next = p;
        else    iq->ns_prepend_list = p;
        iq->ns_prepend_last = p;
        return 1;
}

/**
 * Given a CNAME response (defined as a response containing a CNAME or DNAME
 * that does not answer the request), process the response, modifying the
 * state as necessary. This follows the CNAME/DNAME chain and returns the
 * final query name.
 *
 * sets the new query name, after following the CNAME/DNAME chain.
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param msg: the response.
 * @param mname: returned target new query name.
 * @param mname_len: length of mname.
 * @return false on (malloc) error.
 */
static int
handle_cname_response(struct module_qstate* qstate, struct iter_qstate* iq,
        struct dns_msg* msg, uint8_t** mname, size_t* mname_len)
{
        size_t i;
        /* Start with the (current) qname. */
        *mname = iq->qchase.qname;
        *mname_len = iq->qchase.qname_len;

        /* Iterate over the ANSWER rrsets in order, looking for CNAMEs and 
         * DNAMES. */
        for(i=0; i<msg->rep->an_numrrsets; i++) {
                struct ub_packed_rrset_key* r = msg->rep->rrsets[i];
                /* If there is a (relevant) DNAME, add it to the list.
                 * We always expect there to be CNAME that was generated 
                 * by this DNAME following, so we don't process the DNAME 
                 * directly.  */
                if(ntohs(r->rk.type) == LDNS_RR_TYPE_DNAME &&
                        dname_strict_subdomain_c(*mname, r->rk.dname)) {
                        if(!iter_add_prepend_answer(qstate, iq, r))
                                return 0;
                        continue;
                }

                if(ntohs(r->rk.type) == LDNS_RR_TYPE_CNAME &&
                        query_dname_compare(*mname, r->rk.dname) == 0) {
                        /* Add this relevant CNAME rrset to the prepend list.*/
                        if(!iter_add_prepend_answer(qstate, iq, r))
                                return 0;
                        get_cname_target(r, mname, mname_len);
                }

                /* Other rrsets in the section are ignored. */
        }
        /* add authority rrsets to authority prepend, for wildcarded CNAMEs */
        for(i=msg->rep->an_numrrsets; i<msg->rep->an_numrrsets +
                msg->rep->ns_numrrsets; i++) {
                struct ub_packed_rrset_key* r = msg->rep->rrsets[i];
                /* only add NSEC/NSEC3, as they may be needed for validation */
                if(ntohs(r->rk.type) == LDNS_RR_TYPE_NSEC ||
                        ntohs(r->rk.type) == LDNS_RR_TYPE_NSEC3) {
                        if(!iter_add_prepend_auth(qstate, iq, r))
                                return 0;
                }
        }
        return 1;
}

/** create target count structure for this query */
static void
target_count_create(struct iter_qstate* iq)
{
        if(!iq->target_count) {
                iq->target_count = (int*)calloc(2, sizeof(int));
                /* if calloc fails we simply do not track this number */
                if(iq->target_count)
                        iq->target_count[0] = 1;
        }
}

static void
target_count_increase(struct iter_qstate* iq, int num)
{
        target_count_create(iq);
        if(iq->target_count)
                iq->target_count[1] += num;
}

/**
 * Generate a subrequest.
 * Generate a local request event. Local events are tied to this module, and
 * have a correponding (first tier) event that is waiting for this event to
 * resolve to continue.
 *
 * @param qname The query name for this request.
 * @param qnamelen length of qname
 * @param qtype The query type for this request.
 * @param qclass The query class for this request.
 * @param qstate The event that is generating this event.
 * @param id: module id.
 * @param iq: The iterator state that is generating this event.
 * @param initial_state The initial response state (normally this
 *          is QUERY_RESP_STATE, unless it is known that the request won't
 *          need iterative processing
 * @param finalstate The final state for the response to this request.
 * @param subq_ret: if newly allocated, the subquerystate, or NULL if it does
 *      not need initialisation.
 * @param v: if true, validation is done on the subquery.
 * @return false on error (malloc).
 */
static int
generate_sub_request(uint8_t* qname, size_t qnamelen, uint16_t qtype, 
        uint16_t qclass, struct module_qstate* qstate, int id,
        struct iter_qstate* iq, enum iter_state initial_state, 
        enum iter_state finalstate, struct module_qstate** subq_ret, int v)
{
        struct module_qstate* subq = NULL;
        struct iter_qstate* subiq = NULL;
        uint16_t qflags = 0; /* OPCODE QUERY, no flags */
        struct query_info qinf;
        int prime = (finalstate == PRIME_RESP_STATE)?1:0;
        int valrec = 0;
        qinf.qname = qname;
        qinf.qname_len = qnamelen;
        qinf.qtype = qtype;
        qinf.qclass = qclass;

        /* RD should be set only when sending the query back through the INIT
         * state. */
        if(initial_state == INIT_REQUEST_STATE)
                qflags |= BIT_RD;
        /* We set the CD flag so we can send this through the "head" of 
         * the resolution chain, which might have a validator. We are 
         * uninterested in validating things not on the direct resolution 
         * path.  */
        if(!v) {
                qflags |= BIT_CD;
                valrec = 1;
        }
        
        /* attach subquery, lookup existing or make a new one */
        fptr_ok(fptr_whitelist_modenv_attach_sub(qstate->env->attach_sub));
        if(!(*qstate->env->attach_sub)(qstate, &qinf, qflags, prime, valrec,
                &subq)) {
                return 0;
        }
        *subq_ret = subq;
        if(subq) {
                /* initialise the new subquery */
                subq->curmod = id;
                subq->ext_state[id] = module_state_initial;
                subq->minfo[id] = regional_alloc(subq->region, 
                        sizeof(struct iter_qstate));
                if(!subq->minfo[id]) {
                        log_err("init subq: out of memory");
                        fptr_ok(fptr_whitelist_modenv_kill_sub(
                                qstate->env->kill_sub));
                        (*qstate->env->kill_sub)(subq);
                        return 0;
                }
                subiq = (struct iter_qstate*)subq->minfo[id];
                memset(subiq, 0, sizeof(*subiq));
                subiq->num_target_queries = 0;
                target_count_create(iq);
                subiq->target_count = iq->target_count;
                if(iq->target_count)
                        iq->target_count[0] ++; /* extra reference */
                subiq->num_current_queries = 0;
                subiq->depth = iq->depth+1;
                outbound_list_init(&subiq->outlist);
                subiq->state = initial_state;
                subiq->final_state = finalstate;
                subiq->qchase = subq->qinfo;
                subiq->chase_flags = subq->query_flags;
                subiq->refetch_glue = 0;
        }
        return 1;
}

/**
 * Generate and send a root priming request.
 * @param qstate: the qtstate that triggered the need to prime.
 * @param iq: iterator query state.
 * @param id: module id.
 * @param qclass: the class to prime.
 * @return 0 on failure
 */
static int
prime_root(struct module_qstate* qstate, struct iter_qstate* iq, int id,
        uint16_t qclass)
{
        struct delegpt* dp;
        struct module_qstate* subq;
        verbose(VERB_DETAIL, "priming . %s NS", 
                sldns_lookup_by_id(sldns_rr_classes, (int)qclass)?
                sldns_lookup_by_id(sldns_rr_classes, (int)qclass)->name:"??");
        dp = hints_lookup_root(qstate->env->hints, qclass);
        if(!dp) {
                verbose(VERB_ALGO, "Cannot prime due to lack of hints");
                return 0;
        }
        /* Priming requests start at the QUERYTARGETS state, skipping 
         * the normal INIT state logic (which would cause an infloop). */
        if(!generate_sub_request((uint8_t*)"\000", 1, LDNS_RR_TYPE_NS, 
                qclass, qstate, id, iq, QUERYTARGETS_STATE, PRIME_RESP_STATE,
                &subq, 0)) {
                verbose(VERB_ALGO, "could not prime root");
                return 0;
        }
        if(subq) {
                struct iter_qstate* subiq = 
                        (struct iter_qstate*)subq->minfo[id];
                /* Set the initial delegation point to the hint.
                 * copy dp, it is now part of the root prime query. 
                 * dp was part of in the fixed hints structure. */
                subiq->dp = delegpt_copy(dp, subq->region);
                if(!subiq->dp) {
                        log_err("out of memory priming root, copydp");
                        fptr_ok(fptr_whitelist_modenv_kill_sub(
                                qstate->env->kill_sub));
                        (*qstate->env->kill_sub)(subq);
                        return 0;
                }
                /* there should not be any target queries. */
                subiq->num_target_queries = 0; 
                subiq->dnssec_expected = iter_indicates_dnssec(
                        qstate->env, subiq->dp, NULL, subq->qinfo.qclass);
        }
        
        /* this module stops, our submodule starts, and does the query. */
        qstate->ext_state[id] = module_wait_subquery;
        return 1;
}

/**
 * Generate and process a stub priming request. This method tests for the
 * need to prime a stub zone, so it is safe to call for every request.
 *
 * @param qstate: the qtstate that triggered the need to prime.
 * @param iq: iterator query state.
 * @param id: module id.
 * @param qname: request name.
 * @param qclass: request class.
 * @return true if a priming subrequest was made, false if not. The will only
 *         issue a priming request if it detects an unprimed stub.
 *         Uses value of 2 to signal during stub-prime in root-prime situation
 *         that a noprime-stub is available and resolution can continue.
 */
static int
prime_stub(struct module_qstate* qstate, struct iter_qstate* iq, int id,
        uint8_t* qname, uint16_t qclass)
{
        /* Lookup the stub hint. This will return null if the stub doesn't 
         * need to be re-primed. */
        struct iter_hints_stub* stub;
        struct delegpt* stub_dp;
        struct module_qstate* subq;

        if(!qname) return 0;
        stub = hints_lookup_stub(qstate->env->hints, qname, qclass, iq->dp);
        /* The stub (if there is one) does not need priming. */
        if(!stub)
                return 0;
        stub_dp = stub->dp;

        /* is it a noprime stub (always use) */
        if(stub->noprime) {
                int r = 0;
                if(iq->dp == NULL) r = 2;
                /* copy the dp out of the fixed hints structure, so that
                 * it can be changed when servicing this query */
                iq->dp = delegpt_copy(stub_dp, qstate->region);
                if(!iq->dp) {
                        log_err("out of memory priming stub");
                        (void)error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                        return 1; /* return 1 to make module stop, with error */
                }
                log_nametypeclass(VERB_DETAIL, "use stub", stub_dp->name, 
                        LDNS_RR_TYPE_NS, qclass);
                return r;
        }

        /* Otherwise, we need to (re)prime the stub. */
        log_nametypeclass(VERB_DETAIL, "priming stub", stub_dp->name, 
                LDNS_RR_TYPE_NS, qclass);

        /* Stub priming events start at the QUERYTARGETS state to avoid the
         * redundant INIT state processing. */
        if(!generate_sub_request(stub_dp->name, stub_dp->namelen, 
                LDNS_RR_TYPE_NS, qclass, qstate, id, iq,
                QUERYTARGETS_STATE, PRIME_RESP_STATE, &subq, 0)) {
                verbose(VERB_ALGO, "could not prime stub");
                (void)error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                return 1; /* return 1 to make module stop, with error */
        }
        if(subq) {
                struct iter_qstate* subiq = 
                        (struct iter_qstate*)subq->minfo[id];

                /* Set the initial delegation point to the hint. */
                /* make copy to avoid use of stub dp by different qs/threads */
                subiq->dp = delegpt_copy(stub_dp, subq->region);
                if(!subiq->dp) {
                        log_err("out of memory priming stub, copydp");
                        fptr_ok(fptr_whitelist_modenv_kill_sub(
                                qstate->env->kill_sub));
                        (*qstate->env->kill_sub)(subq);
                        (void)error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                        return 1; /* return 1 to make module stop, with error */
                }
                /* there should not be any target queries -- although there 
                 * wouldn't be anyway, since stub hints never have 
                 * missing targets. */
                subiq->num_target_queries = 0; 
                subiq->wait_priming_stub = 1;
                subiq->dnssec_expected = iter_indicates_dnssec(
                        qstate->env, subiq->dp, NULL, subq->qinfo.qclass);
        }
        
        /* this module stops, our submodule starts, and does the query. */
        qstate->ext_state[id] = module_wait_subquery;
        return 1;
}

/**
 * Generate A and AAAA checks for glue that is in-zone for the referral
 * we just got to obtain authoritative information on the adresses.
 *
 * @param qstate: the qtstate that triggered the need to prime.
 * @param iq: iterator query state.
 * @param id: module id.
 */
static void
generate_a_aaaa_check(struct module_qstate* qstate, struct iter_qstate* iq, 
        int id)
{
        struct iter_env* ie = (struct iter_env*)qstate->env->modinfo[id];
        struct module_qstate* subq;
        size_t i;
        struct reply_info* rep = iq->response->rep;
        struct ub_packed_rrset_key* s;
        log_assert(iq->dp);

        if(iq->depth == ie->max_dependency_depth)
                return;
        /* walk through additional, and check if in-zone,
         * only relevant A, AAAA are left after scrub anyway */
        for(i=rep->an_numrrsets+rep->ns_numrrsets; i<rep->rrset_count; i++) {
                s = rep->rrsets[i];
                /* check *ALL* addresses that are transmitted in additional*/
                /* is it an address ? */
                if( !(ntohs(s->rk.type)==LDNS_RR_TYPE_A ||
                        ntohs(s->rk.type)==LDNS_RR_TYPE_AAAA)) {
                        continue;
                }
                /* is this query the same as the A/AAAA check for it */
                if(qstate->qinfo.qtype == ntohs(s->rk.type) &&
                        qstate->qinfo.qclass == ntohs(s->rk.rrset_class) &&
                        query_dname_compare(qstate->qinfo.qname, 
                                s->rk.dname)==0 &&
                        (qstate->query_flags&BIT_RD) && 
                        !(qstate->query_flags&BIT_CD))
                        continue;

                /* generate subrequest for it */
                log_nametypeclass(VERB_ALGO, "schedule addr fetch", 
                        s->rk.dname, ntohs(s->rk.type), 
                        ntohs(s->rk.rrset_class));
                if(!generate_sub_request(s->rk.dname, s->rk.dname_len, 
                        ntohs(s->rk.type), ntohs(s->rk.rrset_class),
                        qstate, id, iq,
                        INIT_REQUEST_STATE, FINISHED_STATE, &subq, 1)) {
                        verbose(VERB_ALGO, "could not generate addr check");
                        return;
                }
                /* ignore subq - not need for more init */
        }
}

/**
 * Generate a NS check request to obtain authoritative information
 * on an NS rrset.
 *
 * @param qstate: the qtstate that triggered the need to prime.
 * @param iq: iterator query state.
 * @param id: module id.
 */
static void
generate_ns_check(struct module_qstate* qstate, struct iter_qstate* iq, int id)
{
        struct iter_env* ie = (struct iter_env*)qstate->env->modinfo[id];
        struct module_qstate* subq;
        log_assert(iq->dp);

        if(iq->depth == ie->max_dependency_depth)
                return;
        /* is this query the same as the nscheck? */
        if(qstate->qinfo.qtype == LDNS_RR_TYPE_NS &&
                query_dname_compare(iq->dp->name, qstate->qinfo.qname)==0 &&
                (qstate->query_flags&BIT_RD) && !(qstate->query_flags&BIT_CD)){
                /* spawn off A, AAAA queries for in-zone glue to check */
                generate_a_aaaa_check(qstate, iq, id);
                return;
        }

        log_nametypeclass(VERB_ALGO, "schedule ns fetch", 
                iq->dp->name, LDNS_RR_TYPE_NS, iq->qchase.qclass);
        if(!generate_sub_request(iq->dp->name, iq->dp->namelen, 
                LDNS_RR_TYPE_NS, iq->qchase.qclass, qstate, id, iq,
                INIT_REQUEST_STATE, FINISHED_STATE, &subq, 1)) {
                verbose(VERB_ALGO, "could not generate ns check");
                return;
        }
        if(subq) {
                struct iter_qstate* subiq = 
                        (struct iter_qstate*)subq->minfo[id];

                /* make copy to avoid use of stub dp by different qs/threads */
                /* refetch glue to start higher up the tree */
                subiq->refetch_glue = 1;
                subiq->dp = delegpt_copy(iq->dp, subq->region);
                if(!subiq->dp) {
                        log_err("out of memory generating ns check, copydp");
                        fptr_ok(fptr_whitelist_modenv_kill_sub(
                                qstate->env->kill_sub));
                        (*qstate->env->kill_sub)(subq);
                        return;
                }
        }
}

/**
 * Generate a DNSKEY prefetch query to get the DNSKEY for the DS record we
 * just got in a referral (where we have dnssec_expected, thus have trust
 * anchors above it).  Note that right after calling this routine the
 * iterator detached subqueries (because of following the referral), and thus
 * the DNSKEY query becomes detached, its return stored in the cache for
 * later lookup by the validator.  This cache lookup by the validator avoids
 * the roundtrip incurred by the DNSKEY query.  The DNSKEY query is now
 * performed at about the same time the original query is sent to the domain,
 * thus the two answers are likely to be returned at about the same time,
 * saving a roundtrip from the validated lookup.
 *
 * @param qstate: the qtstate that triggered the need to prime.
 * @param iq: iterator query state.
 * @param id: module id.
 */
static void
generate_dnskey_prefetch(struct module_qstate* qstate, 
        struct iter_qstate* iq, int id)
{
        struct module_qstate* subq;
        log_assert(iq->dp);

        /* is this query the same as the prefetch? */
        if(qstate->qinfo.qtype == LDNS_RR_TYPE_DNSKEY &&
                query_dname_compare(iq->dp->name, qstate->qinfo.qname)==0 &&
                (qstate->query_flags&BIT_RD) && !(qstate->query_flags&BIT_CD)){
                return;
        }

        /* if the DNSKEY is in the cache this lookup will stop quickly */
        log_nametypeclass(VERB_ALGO, "schedule dnskey prefetch", 
                iq->dp->name, LDNS_RR_TYPE_DNSKEY, iq->qchase.qclass);
        if(!generate_sub_request(iq->dp->name, iq->dp->namelen, 
                LDNS_RR_TYPE_DNSKEY, iq->qchase.qclass, qstate, id, iq,
                INIT_REQUEST_STATE, FINISHED_STATE, &subq, 0)) {
                /* we'll be slower, but it'll work */
                verbose(VERB_ALGO, "could not generate dnskey prefetch");
                return;
        }
        if(subq) {
                struct iter_qstate* subiq = 
                        (struct iter_qstate*)subq->minfo[id];
                /* this qstate has the right delegation for the dnskey lookup*/
                /* make copy to avoid use of stub dp by different qs/threads */
                subiq->dp = delegpt_copy(iq->dp, subq->region);
                /* if !subiq->dp, it'll start from the cache, no problem */
        }
}

/**
 * See if the query needs forwarding.
 * 
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @return true if the request is forwarded, false if not.
 *      If returns true but, iq->dp is NULL then a malloc failure occurred.
 */
static int
forward_request(struct module_qstate* qstate, struct iter_qstate* iq)
{
        struct delegpt* dp;
        uint8_t* delname = iq->qchase.qname;
        size_t delnamelen = iq->qchase.qname_len;
        if(iq->refetch_glue) {
                delname = iq->dp->name;
                delnamelen = iq->dp->namelen;
        }
        /* strip one label off of DS query to lookup higher for it */
        if( (iq->qchase.qtype == LDNS_RR_TYPE_DS || iq->refetch_glue)
                && !dname_is_root(iq->qchase.qname))
                dname_remove_label(&delname, &delnamelen);
        dp = forwards_lookup(qstate->env->fwds, delname, iq->qchase.qclass);
        if(!dp) 
                return 0;
        /* send recursion desired to forward addr */
        iq->chase_flags |= BIT_RD; 
        iq->dp = delegpt_copy(dp, qstate->region);
        /* iq->dp checked by caller */
        verbose(VERB_ALGO, "forwarding request");
        return 1;
}

/** 
 * Process the initial part of the request handling. This state roughly
 * corresponds to resolver algorithms steps 1 (find answer in cache) and 2
 * (find the best servers to ask).
 *
 * Note that all requests start here, and query restarts revisit this state.
 *
 * This state either generates: 1) a response, from cache or error, 2) a
 * priming event, or 3) forwards the request to the next state (init2,
 * generally).
 *
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param ie: iterator shared global environment.
 * @param id: module id.
 * @return true if the event needs more request processing immediately,
 *         false if not.
 */
static int
processInitRequest(struct module_qstate* qstate, struct iter_qstate* iq,
        struct iter_env* ie, int id)
{
        uint8_t* delname;
        size_t delnamelen;
        struct dns_msg* msg;

        log_query_info(VERB_DETAIL, "resolving", &qstate->qinfo);
        /* check effort */

        /* We enforce a maximum number of query restarts. This is primarily a
         * cheap way to prevent CNAME loops. */
        if(iq->query_restart_count > MAX_RESTART_COUNT) {
                verbose(VERB_QUERY, "request has exceeded the maximum number"
                        " of query restarts with %d", iq->query_restart_count);
                return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
        }

        /* We enforce a maximum recursion/dependency depth -- in general, 
         * this is unnecessary for dependency loops (although it will 
         * catch those), but it provides a sensible limit to the amount 
         * of work required to answer a given query. */
        verbose(VERB_ALGO, "request has dependency depth of %d", iq->depth);
        if(iq->depth > ie->max_dependency_depth) {
                verbose(VERB_QUERY, "request has exceeded the maximum "
                        "dependency depth with depth of %d", iq->depth);
                return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
        }

        /* If the request is qclass=ANY, setup to generate each class */
        if(qstate->qinfo.qclass == LDNS_RR_CLASS_ANY) {
                iq->qchase.qclass = 0;
                return next_state(iq, COLLECT_CLASS_STATE);
        }

        /* Resolver Algorithm Step 1 -- Look for the answer in local data. */

        /* This either results in a query restart (CNAME cache response), a
         * terminating response (ANSWER), or a cache miss (null). */
        
        if(qstate->blacklist) {
                /* if cache, or anything else, was blacklisted then
                 * getting older results from cache is a bad idea, no cache */
                verbose(VERB_ALGO, "cache blacklisted, going to the network");
                msg = NULL;
        } else {
                msg = dns_cache_lookup(qstate->env, iq->qchase.qname, 
                        iq->qchase.qname_len, iq->qchase.qtype, 
                        iq->qchase.qclass, qstate->query_flags,
                        qstate->region, qstate->env->scratch);
                if(!msg && qstate->env->neg_cache) {
                        /* lookup in negative cache; may result in 
                         * NOERROR/NODATA or NXDOMAIN answers that need validation */
                        msg = val_neg_getmsg(qstate->env->neg_cache, &iq->qchase,
                                qstate->region, qstate->env->rrset_cache,
                                qstate->env->scratch_buffer, 
                                *qstate->env->now, 1/*add SOA*/, NULL);
                }
                /* item taken from cache does not match our query name, thus
                 * security needs to be re-examined later */
                if(msg && query_dname_compare(qstate->qinfo.qname,
                        iq->qchase.qname) != 0)
                        msg->rep->security = sec_status_unchecked;
        }
        if(msg) {
                /* handle positive cache response */
                enum response_type type = response_type_from_cache(msg, 
                        &iq->qchase);
                if(verbosity >= VERB_ALGO) {
                        log_dns_msg("msg from cache lookup", &msg->qinfo, 
                                msg->rep);
                        verbose(VERB_ALGO, "msg ttl is %d, prefetch ttl %d", 
                                (int)msg->rep->ttl, 
                                (int)msg->rep->prefetch_ttl);
                }

                if(type == RESPONSE_TYPE_CNAME) {
                        uint8_t* sname = 0;
                        size_t slen = 0;
                        verbose(VERB_ALGO, "returning CNAME response from "
                                "cache");
                        if(!handle_cname_response(qstate, iq, msg, 
                                &sname, &slen))
                                return error_response(qstate, id, 
                                        LDNS_RCODE_SERVFAIL);
                        iq->qchase.qname = sname;
                        iq->qchase.qname_len = slen;
                        /* This *is* a query restart, even if it is a cheap 
                         * one. */
                        iq->dp = NULL;
                        iq->refetch_glue = 0;
                        iq->query_restart_count++;
                        iq->sent_count = 0;
                        sock_list_insert(&qstate->reply_origin, NULL, 0, qstate->region);
                        return next_state(iq, INIT_REQUEST_STATE);
                }

                /* if from cache, NULL, else insert 'cache IP' len=0 */
                if(qstate->reply_origin)
                        sock_list_insert(&qstate->reply_origin, NULL, 0, qstate->region);
                /* it is an answer, response, to final state */
                verbose(VERB_ALGO, "returning answer from cache.");
                iq->response = msg;
                return final_state(iq);
        }
        
        /* attempt to forward the request */
        if(forward_request(qstate, iq))
        {
                if(!iq->dp) {
                        log_err("alloc failure for forward dp");
                        return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                }
                iq->refetch_glue = 0;
                /* the request has been forwarded.
                 * forwarded requests need to be immediately sent to the 
                 * next state, QUERYTARGETS. */
                return next_state(iq, QUERYTARGETS_STATE);
        }

        /* Resolver Algorithm Step 2 -- find the "best" servers. */

        /* first, adjust for DS queries. To avoid the grandparent problem, 
         * we just look for the closest set of server to the parent of qname.
         * When re-fetching glue we also need to ask the parent.
         */
        if(iq->refetch_glue) {
                if(!iq->dp) {
                        log_err("internal or malloc fail: no dp for refetch");
                        return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                }
                delname = iq->dp->name;
                delnamelen = iq->dp->namelen;
        } else {
                delname = iq->qchase.qname;
                delnamelen = iq->qchase.qname_len;
        }
        if(iq->qchase.qtype == LDNS_RR_TYPE_DS || iq->refetch_glue ||
           (iq->qchase.qtype == LDNS_RR_TYPE_NS && qstate->prefetch_leeway)) {
                /* remove first label from delname, root goes to hints,
                 * but only to fetch glue, not for qtype=DS. */
                /* also when prefetching an NS record, fetch it again from
                 * its parent, just as if it expired, so that you do not
                 * get stuck on an older nameserver that gives old NSrecords */
                if(dname_is_root(delname) && (iq->refetch_glue ||
                        (iq->qchase.qtype == LDNS_RR_TYPE_NS &&
                        qstate->prefetch_leeway)))
                        delname = NULL; /* go to root priming */
                else    dname_remove_label(&delname, &delnamelen);
        }
        /* delname is the name to lookup a delegation for. If NULL rootprime */
        while(1) {
                
                /* Lookup the delegation in the cache. If null, then the 
                 * cache needs to be primed for the qclass. */
                if(delname)
                     iq->dp = dns_cache_find_delegation(qstate->env, delname, 
                        delnamelen, iq->qchase.qtype, iq->qchase.qclass, 
                        qstate->region, &iq->deleg_msg,
                        *qstate->env->now+qstate->prefetch_leeway);
                else iq->dp = NULL;

                /* If the cache has returned nothing, then we have a 
                 * root priming situation. */
                if(iq->dp == NULL) {
                        /* if there is a stub, then no root prime needed */
                        int r = prime_stub(qstate, iq, id, delname,
                                iq->qchase.qclass);
                        if(r == 2)
                                break; /* got noprime-stub-zone, continue */
                        else if(r)
                                return 0; /* stub prime request made */
                        if(forwards_lookup_root(qstate->env->fwds, 
                                iq->qchase.qclass)) {
                                /* forward zone root, no root prime needed */
                                /* fill in some dp - safety belt */
                                iq->dp = hints_lookup_root(qstate->env->hints, 
                                        iq->qchase.qclass);
                                if(!iq->dp) {
                                        log_err("internal error: no hints dp");
                                        return error_response(qstate, id, 
                                                LDNS_RCODE_SERVFAIL);
                                }
                                iq->dp = delegpt_copy(iq->dp, qstate->region);
                                if(!iq->dp) {
                                        log_err("out of memory in safety belt");
                                        return error_response(qstate, id, 
                                                LDNS_RCODE_SERVFAIL);
                                }
                                return next_state(iq, INIT_REQUEST_2_STATE);
                        }
                        /* Note that the result of this will set a new
                         * DelegationPoint based on the result of priming. */
                        if(!prime_root(qstate, iq, id, iq->qchase.qclass))
                                return error_response(qstate, id, 
                                        LDNS_RCODE_REFUSED);

                        /* priming creates and sends a subordinate query, with 
                         * this query as the parent. So further processing for 
                         * this event will stop until reactivated by the 
                         * results of priming. */
                        return 0;
                }

                /* see if this dp not useless.
                 * It is useless if:
                 *      o all NS items are required glue. 
                 *        or the query is for NS item that is required glue.
                 *      o no addresses are provided.
                 *      o RD qflag is on.
                 * Instead, go up one level, and try to get even further
                 * If the root was useless, use safety belt information. 
                 * Only check cache returns, because replies for servers
                 * could be useless but lead to loops (bumping into the
                 * same server reply) if useless-checked.
                 */
                if(iter_dp_is_useless(&qstate->qinfo, qstate->query_flags, 
                        iq->dp)) {
                        if(dname_is_root(iq->dp->name)) {
                                /* use safety belt */
                                verbose(VERB_QUERY, "Cache has root NS but "
                                "no addresses. Fallback to the safety belt.");
                                iq->dp = hints_lookup_root(qstate->env->hints, 
                                        iq->qchase.qclass);
                                /* note deleg_msg is from previous lookup,
                                 * but RD is on, so it is not used */
                                if(!iq->dp) {
                                        log_err("internal error: no hints dp");
                                        return error_response(qstate, id, 
                                                LDNS_RCODE_REFUSED);
                                }
                                iq->dp = delegpt_copy(iq->dp, qstate->region);
                                if(!iq->dp) {
                                        log_err("out of memory in safety belt");
                                        return error_response(qstate, id, 
                                                LDNS_RCODE_SERVFAIL);
                                }
                                break;
                        } else {
                                verbose(VERB_ALGO, 
                                        "cache delegation was useless:");
                                delegpt_log(VERB_ALGO, iq->dp);
                                /* go up */
                                delname = iq->dp->name;
                                delnamelen = iq->dp->namelen;
                                dname_remove_label(&delname, &delnamelen);
                        }
                } else break;
        }

        verbose(VERB_ALGO, "cache delegation returns delegpt");
        delegpt_log(VERB_ALGO, iq->dp);

        /* Otherwise, set the current delegation point and move on to the 
         * next state. */
        return next_state(iq, INIT_REQUEST_2_STATE);
}

/** 
 * Process the second part of the initial request handling. This state
 * basically exists so that queries that generate root priming events have
 * the same init processing as ones that do not. Request events that reach
 * this state must have a valid currentDelegationPoint set.
 *
 * This part is primarly handling stub zone priming. Events that reach this
 * state must have a current delegation point.
 *
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param id: module id.
 * @return true if the event needs more request processing immediately,
 *         false if not.
 */
static int
processInitRequest2(struct module_qstate* qstate, struct iter_qstate* iq,
        int id)
{
        uint8_t* delname;
        size_t delnamelen;
        log_query_info(VERB_QUERY, "resolving (init part 2): ", 
                &qstate->qinfo);

        if(iq->refetch_glue) {
                if(!iq->dp) {
                        log_err("internal or malloc fail: no dp for refetch");
                        return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                }
                delname = iq->dp->name;
                delnamelen = iq->dp->namelen;
        } else {
                delname = iq->qchase.qname;
                delnamelen = iq->qchase.qname_len;
        }
        if(iq->qchase.qtype == LDNS_RR_TYPE_DS || iq->refetch_glue) {
                if(!dname_is_root(delname))
                        dname_remove_label(&delname, &delnamelen);
                iq->refetch_glue = 0; /* if CNAME causes restart, no refetch */
        }
        /* Check to see if we need to prime a stub zone. */
        if(prime_stub(qstate, iq, id, delname, iq->qchase.qclass)) {
                /* A priming sub request was made */
                return 0;
        }

        /* most events just get forwarded to the next state. */
        return next_state(iq, INIT_REQUEST_3_STATE);
}

/** 
 * Process the third part of the initial request handling. This state exists
 * as a separate state so that queries that generate stub priming events
 * will get the tail end of the init process but not repeat the stub priming
 * check.
 *
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param id: module id.
 * @return true, advancing the event to the QUERYTARGETS_STATE.
 */
static int
processInitRequest3(struct module_qstate* qstate, struct iter_qstate* iq, 
        int id)
{
        log_query_info(VERB_QUERY, "resolving (init part 3): ", 
                &qstate->qinfo);
        /* if the cache reply dp equals a validation anchor or msg has DS,
         * then DNSSEC RRSIGs are expected in the reply */
        iq->dnssec_expected = iter_indicates_dnssec(qstate->env, iq->dp, 
                iq->deleg_msg, iq->qchase.qclass);

        /* If the RD flag wasn't set, then we just finish with the 
         * cached referral as the response. */
        if(!(qstate->query_flags & BIT_RD)) {
                iq->response = iq->deleg_msg;
                if(verbosity >= VERB_ALGO && iq->response)
                        log_dns_msg("no RD requested, using delegation msg", 
                                &iq->response->qinfo, iq->response->rep);
                if(qstate->reply_origin)
                        sock_list_insert(&qstate->reply_origin, NULL, 0, qstate->region);
                return final_state(iq);
        }
        /* After this point, unset the RD flag -- this query is going to 
         * be sent to an auth. server. */
        iq->chase_flags &= ~BIT_RD;

        /* if dnssec expected, fetch key for the trust-anchor or cached-DS */
        if(iq->dnssec_expected && qstate->env->cfg->prefetch_key &&
                !(qstate->query_flags&BIT_CD)) {
                generate_dnskey_prefetch(qstate, iq, id);
                fptr_ok(fptr_whitelist_modenv_detach_subs(
                        qstate->env->detach_subs));
                (*qstate->env->detach_subs)(qstate);
        }

        /* Jump to the next state. */
        return next_state(iq, QUERYTARGETS_STATE);
}

/**
 * Given a basic query, generate a parent-side "target" query. 
 * These are subordinate queries for missing delegation point target addresses,
 * for which only the parent of the delegation provides correct IP addresses.
 *
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param id: module id.
 * @param name: target qname.
 * @param namelen: target qname length.
 * @param qtype: target qtype (either A or AAAA).
 * @param qclass: target qclass.
 * @return true on success, false on failure.
 */
static int
generate_parentside_target_query(struct module_qstate* qstate, 
        struct iter_qstate* iq, int id, uint8_t* name, size_t namelen, 
        uint16_t qtype, uint16_t qclass)
{
        struct module_qstate* subq;
        if(!generate_sub_request(name, namelen, qtype, qclass, qstate, 
                id, iq, INIT_REQUEST_STATE, FINISHED_STATE, &subq, 0))
                return 0;
        if(subq) {
                struct iter_qstate* subiq = 
                        (struct iter_qstate*)subq->minfo[id];
                /* blacklist the cache - we want to fetch parent stuff */
                sock_list_insert(&subq->blacklist, NULL, 0, subq->region);
                subiq->query_for_pside_glue = 1;
                if(dname_subdomain_c(name, iq->dp->name)) {
                        subiq->dp = delegpt_copy(iq->dp, subq->region);
                        subiq->dnssec_expected = iter_indicates_dnssec(
                                qstate->env, subiq->dp, NULL, 
                                subq->qinfo.qclass);
                        subiq->refetch_glue = 1;
                } else {
                        subiq->dp = dns_cache_find_delegation(qstate->env, 
                                name, namelen, qtype, qclass, subq->region,
                                &subiq->deleg_msg,
                                *qstate->env->now+subq->prefetch_leeway); 
                        /* if no dp, then it's from root, refetch unneeded */
                        if(subiq->dp) { 
                                subiq->dnssec_expected = iter_indicates_dnssec(
                                        qstate->env, subiq->dp, NULL, 
                                        subq->qinfo.qclass);
                                subiq->refetch_glue = 1;
                        }
                }
        }
        log_nametypeclass(VERB_QUERY, "new pside target", name, qtype, qclass);
        return 1;
}

/**
 * Given a basic query, generate a "target" query. These are subordinate
 * queries for missing delegation point target addresses.
 *
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param id: module id.
 * @param name: target qname.
 * @param namelen: target qname length.
 * @param qtype: target qtype (either A or AAAA).
 * @param qclass: target qclass.
 * @return true on success, false on failure.
 */
static int
generate_target_query(struct module_qstate* qstate, struct iter_qstate* iq,
        int id, uint8_t* name, size_t namelen, uint16_t qtype, uint16_t qclass)
{
        struct module_qstate* subq;
        if(!generate_sub_request(name, namelen, qtype, qclass, qstate, 
                id, iq, INIT_REQUEST_STATE, FINISHED_STATE, &subq, 0))
                return 0;
        log_nametypeclass(VERB_QUERY, "new target", name, qtype, qclass);
        return 1;
}

/**
 * Given an event at a certain state, generate zero or more target queries
 * for it's current delegation point.
 *
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param ie: iterator shared global environment.
 * @param id: module id.
 * @param maxtargets: The maximum number of targets to query for.
 *      if it is negative, there is no maximum number of targets.
 * @param num: returns the number of queries generated and processed, 
 *      which may be zero if there were no missing targets.
 * @return false on error.
 */
static int
query_for_targets(struct module_qstate* qstate, struct iter_qstate* iq,
        struct iter_env* ie, int id, int maxtargets, int* num)
{
        int query_count = 0;
        struct delegpt_ns* ns;
        int missing;
        int toget = 0;

        if(iq->depth == ie->max_dependency_depth)
                return 0;
        if(iq->depth > 0 && iq->target_count &&
                iq->target_count[1] > MAX_TARGET_COUNT) {
                verbose(VERB_QUERY, "request has exceeded the maximum "
                        "number of glue fetches %d", iq->target_count[1]);
                return 0;
        }

        iter_mark_cycle_targets(qstate, iq->dp);
        missing = (int)delegpt_count_missing_targets(iq->dp);
        log_assert(maxtargets != 0); /* that would not be useful */

        /* Generate target requests. Basically, any missing targets 
         * are queried for here, regardless if it is necessary to do 
         * so to continue processing. */
        if(maxtargets < 0 || maxtargets > missing)
                toget = missing;
        else    toget = maxtargets;
        if(toget == 0) {
                *num = 0;
                return 1;
        }
        /* select 'toget' items from the total of 'missing' items */
        log_assert(toget <= missing);

        /* loop over missing targets */
        for(ns = iq->dp->nslist; ns; ns = ns->next) {
                if(ns->resolved)
                        continue;

                /* randomly select this item with probability toget/missing */
                if(!iter_ns_probability(qstate->env->rnd, toget, missing)) {
                        /* do not select this one, next; select toget number
                         * of items from a list one less in size */
                        missing --;
                        continue;
                }

                if(ie->supports_ipv6 && !ns->got6) {
                        /* Send the AAAA request. */
                        if(!generate_target_query(qstate, iq, id, 
                                ns->name, ns->namelen,
                                LDNS_RR_TYPE_AAAA, iq->qchase.qclass)) {
                                *num = query_count;
                                if(query_count > 0)
                                        qstate->ext_state[id] = module_wait_subquery;
                                return 0;
                        }
                        query_count++;
                }
                /* Send the A request. */
                if(ie->supports_ipv4 && !ns->got4) {
                        if(!generate_target_query(qstate, iq, id, 
                                ns->name, ns->namelen, 
                                LDNS_RR_TYPE_A, iq->qchase.qclass)) {
                                *num = query_count;
                                if(query_count > 0)
                                        qstate->ext_state[id] = module_wait_subquery;
                                return 0;
                        }
                        query_count++;
                }

                /* mark this target as in progress. */
                ns->resolved = 1;
                missing--;
                toget--;
                if(toget == 0)
                        break;
        }
        *num = query_count;
        if(query_count > 0)
                qstate->ext_state[id] = module_wait_subquery;

        return 1;
}

/** see if last resort is possible - does config allow queries to parent */
static int
can_have_last_resort(struct module_env* env, struct delegpt* dp,
        struct iter_qstate* iq)
{
        struct delegpt* fwddp;
        struct iter_hints_stub* stub;
        /* do not process a last resort (the parent side) if a stub
         * or forward is configured, because we do not want to go 'above'
         * the configured servers */
        if(!dname_is_root(dp->name) && (stub = (struct iter_hints_stub*)
                name_tree_find(&env->hints->tree, dp->name, dp->namelen,
                dp->namelabs, iq->qchase.qclass)) &&
                /* has_parent side is turned off for stub_first, where we
                 * are allowed to go to the parent */
                stub->dp->has_parent_side_NS) {
                verbose(VERB_QUERY, "configured stub servers failed -- returning SERVFAIL");
                return 0;
        }
        if((fwddp = forwards_find(env->fwds, dp->name, iq->qchase.qclass)) &&
                /* has_parent_side is turned off for forward_first, where
                 * we are allowed to go to the parent */
                fwddp->has_parent_side_NS) {
                verbose(VERB_QUERY, "configured forward servers failed -- returning SERVFAIL");
                return 0;
        }
        return 1;
}

/**
 * Called by processQueryTargets when it would like extra targets to query
 * but it seems to be out of options.  At last resort some less appealing
 * options are explored.  If there are no more options, the result is SERVFAIL
 *
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param ie: iterator shared global environment.
 * @param id: module id.
 * @return true if the event requires more request processing immediately,
 *         false if not. 
 */
static int
processLastResort(struct module_qstate* qstate, struct iter_qstate* iq,
        struct iter_env* ie, int id)
{
        struct delegpt_ns* ns;
        int query_count = 0;
        verbose(VERB_ALGO, "No more query targets, attempting last resort");
        log_assert(iq->dp);

        if(!can_have_last_resort(qstate->env, iq->dp, iq)) {
                /* fail -- no more targets, no more hope of targets, no hope 
                 * of a response. */
                return error_response_cache(qstate, id, LDNS_RCODE_SERVFAIL);
        }
        if(!iq->dp->has_parent_side_NS && dname_is_root(iq->dp->name)) {
                struct delegpt* p = hints_lookup_root(qstate->env->hints,
                        iq->qchase.qclass);
                if(p) {
                        struct delegpt_ns* ns;
                        struct delegpt_addr* a;
                        iq->chase_flags &= ~BIT_RD; /* go to authorities */
                        for(ns = p->nslist; ns; ns=ns->next) {
                                (void)delegpt_add_ns(iq->dp, qstate->region,
                                        ns->name, ns->lame);
                        }
                        for(a = p->target_list; a; a=a->next_target) {
                                (void)delegpt_add_addr(iq->dp, qstate->region,
                                        &a->addr, a->addrlen, a->bogus,
                                        a->lame);
                        }
                }
                iq->dp->has_parent_side_NS = 1;
        } else if(!iq->dp->has_parent_side_NS) {
                if(!iter_lookup_parent_NS_from_cache(qstate->env, iq->dp,
                        qstate->region, &qstate->qinfo) 
                        || !iq->dp->has_parent_side_NS) {
                        /* if: malloc failure in lookup go up to try */
                        /* if: no parent NS in cache - go up one level */
                        verbose(VERB_ALGO, "try to grab parent NS");
                        iq->store_parent_NS = iq->dp;
                        iq->chase_flags &= ~BIT_RD; /* go to authorities */
                        iq->deleg_msg = NULL;
                        iq->refetch_glue = 1;
                        iq->query_restart_count++;
                        iq->sent_count = 0;
                        return next_state(iq, INIT_REQUEST_STATE);
                }
        }
        /* see if that makes new names available */
        if(!cache_fill_missing(qstate->env, iq->qchase.qclass, 
                qstate->region, iq->dp))
                log_err("out of memory in cache_fill_missing");
        if(iq->dp->usable_list) {
                verbose(VERB_ALGO, "try parent-side-name, w. glue from cache");
                return next_state(iq, QUERYTARGETS_STATE);
        }
        /* try to fill out parent glue from cache */
        if(iter_lookup_parent_glue_from_cache(qstate->env, iq->dp,
                qstate->region, &qstate->qinfo)) {
                /* got parent stuff from cache, see if we can continue */
                verbose(VERB_ALGO, "try parent-side glue from cache");
                return next_state(iq, QUERYTARGETS_STATE);
        }
        /* query for an extra name added by the parent-NS record */
        if(delegpt_count_missing_targets(iq->dp) > 0) {
                int qs = 0;
                verbose(VERB_ALGO, "try parent-side target name");
                if(!query_for_targets(qstate, iq, ie, id, 1, &qs)) {
                        return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                }
                iq->num_target_queries += qs;
                target_count_increase(iq, qs);
                if(qs != 0) {
                        qstate->ext_state[id] = module_wait_subquery;
                        return 0; /* and wait for them */
                }
        }
        if(iq->depth == ie->max_dependency_depth) {
                verbose(VERB_QUERY, "maxdepth and need more nameservers, fail");
                return error_response_cache(qstate, id, LDNS_RCODE_SERVFAIL);
        }
        if(iq->depth > 0 && iq->target_count &&
                iq->target_count[1] > MAX_TARGET_COUNT) {
                verbose(VERB_QUERY, "request has exceeded the maximum "
                        "number of glue fetches %d", iq->target_count[1]);
                return error_response_cache(qstate, id, LDNS_RCODE_SERVFAIL);
        }
        /* mark cycle targets for parent-side lookups */
        iter_mark_pside_cycle_targets(qstate, iq->dp);
        /* see if we can issue queries to get nameserver addresses */
        /* this lookup is not randomized, but sequential. */
        for(ns = iq->dp->nslist; ns; ns = ns->next) {
                /* query for parent-side A and AAAA for nameservers */
                if(ie->supports_ipv6 && !ns->done_pside6) {
                        /* Send the AAAA request. */
                        if(!generate_parentside_target_query(qstate, iq, id, 
                                ns->name, ns->namelen,
                                LDNS_RR_TYPE_AAAA, iq->qchase.qclass))
                                return error_response(qstate, id,
                                        LDNS_RCODE_SERVFAIL);
                        ns->done_pside6 = 1;
                        query_count++;
                }
                if(ie->supports_ipv4 && !ns->done_pside4) {
                        /* Send the A request. */
                        if(!generate_parentside_target_query(qstate, iq, id, 
                                ns->name, ns->namelen, 
                                LDNS_RR_TYPE_A, iq->qchase.qclass))
                                return error_response(qstate, id,
                                        LDNS_RCODE_SERVFAIL);
                        ns->done_pside4 = 1;
                        query_count++;
                }
                if(query_count != 0) { /* suspend to await results */
                        verbose(VERB_ALGO, "try parent-side glue lookup");
                        iq->num_target_queries += query_count;
                        target_count_increase(iq, query_count);
                        qstate->ext_state[id] = module_wait_subquery;
                        return 0;
                }
        }

        /* if this was a parent-side glue query itself, then store that
         * failure in cache. */
        if(iq->query_for_pside_glue && !iq->pside_glue)
                iter_store_parentside_neg(qstate->env, &qstate->qinfo,
                        iq->deleg_msg?iq->deleg_msg->rep:
                        (iq->response?iq->response->rep:NULL));

        verbose(VERB_QUERY, "out of query targets -- returning SERVFAIL");
        /* fail -- no more targets, no more hope of targets, no hope 
         * of a response. */
        return error_response_cache(qstate, id, LDNS_RCODE_SERVFAIL);
}

/** 
 * Try to find the NS record set that will resolve a qtype DS query. Due
 * to grandparent/grandchild reasons we did not get a proper lookup right
 * away.  We need to create type NS queries until we get the right parent
 * for this lookup.  We remove labels from the query to find the right point.
 * If we end up at the old dp name, then there is no solution.
 * 
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param id: module id.
 * @return true if the event requires more immediate processing, false if
 *         not. This is generally only true when forwarding the request to
 *         the final state (i.e., on answer).
 */
static int
processDSNSFind(struct module_qstate* qstate, struct iter_qstate* iq, int id)
{
        struct module_qstate* subq = NULL;
        verbose(VERB_ALGO, "processDSNSFind");

        if(!iq->dsns_point) {
                /* initialize */
                iq->dsns_point = iq->qchase.qname;
                iq->dsns_point_len = iq->qchase.qname_len;
        }
        /* robustcheck for internal error: we are not underneath the dp */
        if(!dname_subdomain_c(iq->dsns_point, iq->dp->name)) {
                return error_response_cache(qstate, id, LDNS_RCODE_SERVFAIL);
        }

        /* go up one (more) step, until we hit the dp, if so, end */
        dname_remove_label(&iq->dsns_point, &iq->dsns_point_len);
        if(query_dname_compare(iq->dsns_point, iq->dp->name) == 0) {
                /* there was no inbetween nameserver, use the old delegation
                 * point again.  And this time, because dsns_point is nonNULL
                 * we are going to accept the (bad) result */
                iq->state = QUERYTARGETS_STATE;
                return 1;
        }
        iq->state = DSNS_FIND_STATE;

        /* spawn NS lookup (validation not needed, this is for DS lookup) */
        log_nametypeclass(VERB_ALGO, "fetch nameservers", 
                iq->dsns_point, LDNS_RR_TYPE_NS, iq->qchase.qclass);
        if(!generate_sub_request(iq->dsns_point, iq->dsns_point_len, 
                LDNS_RR_TYPE_NS, iq->qchase.qclass, qstate, id, iq,
                INIT_REQUEST_STATE, FINISHED_STATE, &subq, 0)) {
                return error_response_cache(qstate, id, LDNS_RCODE_SERVFAIL);
        }

        return 0;
}
        
/** 
 * This is the request event state where the request will be sent to one of
 * its current query targets. This state also handles issuing target lookup
 * queries for missing target IP addresses. Queries typically iterate on
 * this state, both when they are just trying different targets for a given
 * delegation point, and when they change delegation points. This state
 * roughly corresponds to RFC 1034 algorithm steps 3 and 4.
 *
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param ie: iterator shared global environment.
 * @param id: module id.
 * @return true if the event requires more request processing immediately,
 *         false if not. This state only returns true when it is generating
 *         a SERVFAIL response because the query has hit a dead end.
 */
static int
processQueryTargets(struct module_qstate* qstate, struct iter_qstate* iq,
        struct iter_env* ie, int id)
{
        int tf_policy;
        struct delegpt_addr* target;
        struct outbound_entry* outq;

        /* NOTE: a request will encounter this state for each target it 
         * needs to send a query to. That is, at least one per referral, 
         * more if some targets timeout or return throwaway answers. */

        log_query_info(VERB_QUERY, "processQueryTargets:", &qstate->qinfo);
        verbose(VERB_ALGO, "processQueryTargets: targetqueries %d, "
                "currentqueries %d sentcount %d", iq->num_target_queries, 
                iq->num_current_queries, iq->sent_count);

        /* Make sure that we haven't run away */
        /* FIXME: is this check even necessary? */
        if(iq->referral_count > MAX_REFERRAL_COUNT) {
                verbose(VERB_QUERY, "request has exceeded the maximum "
                        "number of referrrals with %d", iq->referral_count);
                return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
        }
        if(iq->sent_count > MAX_SENT_COUNT) {
                verbose(VERB_QUERY, "request has exceeded the maximum "
                        "number of sends with %d", iq->sent_count);
                return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
        }
        
        /* Make sure we have a delegation point, otherwise priming failed
         * or another failure occurred */
        if(!iq->dp) {
                verbose(VERB_QUERY, "Failed to get a delegation, giving up");
                return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
        }
        if(!ie->supports_ipv6)
                delegpt_no_ipv6(iq->dp);
        if(!ie->supports_ipv4)
                delegpt_no_ipv4(iq->dp);
        delegpt_log(VERB_ALGO, iq->dp);

        if(iq->num_current_queries>0) {
                /* already busy answering a query, this restart is because
                 * more delegpt addrs became available, wait for existing
                 * query. */
                verbose(VERB_ALGO, "woke up, but wait for outstanding query");
                qstate->ext_state[id] = module_wait_reply;
                return 0;
        }

        tf_policy = 0;
        /* < not <=, because although the array is large enough for <=, the
         * generated query will immediately be discarded due to depth and
         * that servfail is cached, which is not good as opportunism goes. */
        if(iq->depth < ie->max_dependency_depth
                && iq->sent_count < TARGET_FETCH_STOP) {
                tf_policy = ie->target_fetch_policy[iq->depth];
        }

        /* if in 0x20 fallback get as many targets as possible */
        if(iq->caps_fallback) {
                int extra = 0;
                size_t naddr, nres, navail;
                if(!query_for_targets(qstate, iq, ie, id, -1, &extra)) {
                        return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                }
                iq->num_target_queries += extra;
                target_count_increase(iq, extra);
                if(iq->num_target_queries > 0) {
                        /* wait to get all targets, we want to try em */
                        verbose(VERB_ALGO, "wait for all targets for fallback");
                        qstate->ext_state[id] = module_wait_reply;
                        return 0;
                }
                /* did we do enough fallback queries already? */
                delegpt_count_addr(iq->dp, &naddr, &nres, &navail);
                /* the current caps_server is the number of fallbacks sent.
                 * the original query is one that matched too, so we have
                 * caps_server+1 number of matching queries now */
                if(iq->caps_server+1 >= naddr*3 ||
                        iq->caps_server+1 >= MAX_SENT_COUNT) {
                        /* we're done, process the response */
                        verbose(VERB_ALGO, "0x20 fallback had %d responses "
                                "match for %d wanted, done.", 
                                (int)iq->caps_server+1, (int)naddr*3);
                        iq->caps_fallback = 0;
                        iter_dec_attempts(iq->dp, 3); /* space for fallback */
                        iq->num_current_queries++; /* RespState decrements it*/
                        iq->referral_count++; /* make sure we don't loop */
                        iq->sent_count = 0;
                        iq->state = QUERY_RESP_STATE;
                        return 1;
                }
                verbose(VERB_ALGO, "0x20 fallback number %d", 
                        (int)iq->caps_server);

        /* if there is a policy to fetch missing targets 
         * opportunistically, do it. we rely on the fact that once a 
         * query (or queries) for a missing name have been issued, 
         * they will not show up again. */
        } else if(tf_policy != 0) {
                int extra = 0;
                verbose(VERB_ALGO, "attempt to get extra %d targets", 
                        tf_policy);
                (void)query_for_targets(qstate, iq, ie, id, tf_policy, &extra);
                /* errors ignored, these targets are not strictly necessary for
                 * this result, we do not have to reply with SERVFAIL */
                iq->num_target_queries += extra;
                target_count_increase(iq, extra);
        }

        /* Add the current set of unused targets to our queue. */
        delegpt_add_unused_targets(iq->dp);

        /* Select the next usable target, filtering out unsuitable targets. */
        target = iter_server_selection(ie, qstate->env, iq->dp, 
                iq->dp->name, iq->dp->namelen, iq->qchase.qtype,
                &iq->dnssec_lame_query, &iq->chase_to_rd, 
                iq->num_target_queries, qstate->blacklist);

        /* If no usable target was selected... */
        if(!target) {
                /* Here we distinguish between three states: generate a new 
                 * target query, just wait, or quit (with a SERVFAIL).
                 * We have the following information: number of active 
                 * target queries, number of active current queries, 
                 * the presence of missing targets at this delegation 
                 * point, and the given query target policy. */
                
                /* Check for the wait condition. If this is true, then 
                 * an action must be taken. */
                if(iq->num_target_queries==0 && iq->num_current_queries==0) {
                        /* If there is nothing to wait for, then we need 
                         * to distinguish between generating (a) new target 
                         * query, or failing. */
                        if(delegpt_count_missing_targets(iq->dp) > 0) {
                                int qs = 0;
                                verbose(VERB_ALGO, "querying for next "
                                        "missing target");
                                if(!query_for_targets(qstate, iq, ie, id, 
                                        1, &qs)) {
                                        return error_response(qstate, id,
                                                LDNS_RCODE_SERVFAIL);
                                }
                                if(qs == 0 && 
                                   delegpt_count_missing_targets(iq->dp) == 0){
                                        /* it looked like there were missing
                                         * targets, but they did not turn up.
                                         * Try the bad choices again (if any),
                                         * when we get back here missing==0,
                                         * so this is not a loop. */
                                        return 1;
                                }
                                iq->num_target_queries += qs;
                                target_count_increase(iq, qs);
                        }
                        /* Since a target query might have been made, we 
                         * need to check again. */
                        if(iq->num_target_queries == 0) {
                                return processLastResort(qstate, iq, ie, id);
                        }
                }

                /* otherwise, we have no current targets, so submerge 
                 * until one of the target or direct queries return. */
                if(iq->num_target_queries>0 && iq->num_current_queries>0) {
                        verbose(VERB_ALGO, "no current targets -- waiting "
                                "for %d targets to resolve or %d outstanding"
                                " queries to respond", iq->num_target_queries, 
                                iq->num_current_queries);
                        qstate->ext_state[id] = module_wait_reply;
                } else if(iq->num_target_queries>0) {
                        verbose(VERB_ALGO, "no current targets -- waiting "
                                "for %d targets to resolve.",
                                iq->num_target_queries);
                        qstate->ext_state[id] = module_wait_subquery;
                } else {
                        verbose(VERB_ALGO, "no current targets -- waiting "
                                "for %d outstanding queries to respond.",
                                iq->num_current_queries);
                        qstate->ext_state[id] = module_wait_reply;
                }
                return 0;
        }

        /* We have a valid target. */
        if(verbosity >= VERB_QUERY) {
                log_query_info(VERB_QUERY, "sending query:", &iq->qchase);
                log_name_addr(VERB_QUERY, "sending to target:", iq->dp->name, 
                        &target->addr, target->addrlen);
                verbose(VERB_ALGO, "dnssec status: %s%s",
                        iq->dnssec_expected?"expected": "not expected",
                        iq->dnssec_lame_query?" but lame_query anyway": "");
        }
        fptr_ok(fptr_whitelist_modenv_send_query(qstate->env->send_query));
        outq = (*qstate->env->send_query)(
                iq->qchase.qname, iq->qchase.qname_len, 
                iq->qchase.qtype, iq->qchase.qclass, 
                iq->chase_flags | (iq->chase_to_rd?BIT_RD:0), EDNS_DO|BIT_CD, 
                iq->dnssec_expected, iq->caps_fallback, &target->addr,
                target->addrlen, iq->dp->name, iq->dp->namelen, qstate);
        if(!outq) {
                log_addr(VERB_DETAIL, "error sending query to auth server", 
                        &target->addr, target->addrlen);
                return next_state(iq, QUERYTARGETS_STATE);
        }
        outbound_list_insert(&iq->outlist, outq);
        iq->num_current_queries++;
        iq->sent_count++;
        qstate->ext_state[id] = module_wait_reply;

        return 0;
}

/** find NS rrset in given list */
static struct ub_packed_rrset_key*
find_NS(struct reply_info* rep, size_t from, size_t to)
{
        size_t i;
        for(i=from; i<to; i++) {
                if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NS)
                        return rep->rrsets[i];
        }
        return NULL;
}


/** 
 * Process the query response. All queries end up at this state first. This
 * process generally consists of analyzing the response and routing the
 * event to the next state (either bouncing it back to a request state, or
 * terminating the processing for this event).
 * 
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param id: module id.
 * @return true if the event requires more immediate processing, false if
 *         not. This is generally only true when forwarding the request to
 *         the final state (i.e., on answer).
 */
static int
processQueryResponse(struct module_qstate* qstate, struct iter_qstate* iq,
        int id)
{
        int dnsseclame = 0;
        enum response_type type;
        iq->num_current_queries--;
        if(iq->response == NULL) {
                iq->chase_to_rd = 0;
                iq->dnssec_lame_query = 0;
                verbose(VERB_ALGO, "query response was timeout");
                return next_state(iq, QUERYTARGETS_STATE);
        }
        type = response_type_from_server(
                (int)((iq->chase_flags&BIT_RD) || iq->chase_to_rd),
                iq->response, &iq->qchase, iq->dp);
        iq->chase_to_rd = 0;
        if(type == RESPONSE_TYPE_REFERRAL && (iq->chase_flags&BIT_RD)) {
                /* When forwarding (RD bit is set), we handle referrals 
                 * differently. No queries should be sent elsewhere */
                type = RESPONSE_TYPE_ANSWER;
        }
        if(iq->dnssec_expected && !iq->dnssec_lame_query &&
                !(iq->chase_flags&BIT_RD) 
                && type != RESPONSE_TYPE_LAME 
                && type != RESPONSE_TYPE_REC_LAME 
                && type != RESPONSE_TYPE_THROWAWAY 
                && type != RESPONSE_TYPE_UNTYPED) {
                /* a possible answer, see if it is missing DNSSEC */
                /* but not when forwarding, so we dont mark fwder lame */
                if(!iter_msg_has_dnssec(iq->response)) {
                        /* Mark this address as dnsseclame in this dp,
                         * because that will make serverselection disprefer
                         * it, but also, once it is the only final option,
                         * use dnssec-lame-bypass if it needs to query there.*/
                        if(qstate->reply) {
                                struct delegpt_addr* a = delegpt_find_addr(
                                        iq->dp, &qstate->reply->addr,
                                        qstate->reply->addrlen);
                                if(a) a->dnsseclame = 1;
                        }
                        /* test the answer is from the zone we expected,
                         * otherwise, (due to parent,child on same server), we
                         * might mark the server,zone lame inappropriately */
                        if(!iter_msg_from_zone(iq->response, iq->dp, type,
                                iq->qchase.qclass))
                                qstate->reply = NULL;
                        type = RESPONSE_TYPE_LAME;
                        dnsseclame = 1;
                }
        } else iq->dnssec_lame_query = 0;
        /* see if referral brings us close to the target */
        if(type == RESPONSE_TYPE_REFERRAL) {
                struct ub_packed_rrset_key* ns = find_NS(
                        iq->response->rep, iq->response->rep->an_numrrsets,
                        iq->response->rep->an_numrrsets 
                        + iq->response->rep->ns_numrrsets);
                if(!ns) ns = find_NS(iq->response->rep, 0, 
                                iq->response->rep->an_numrrsets);
                if(!ns || !dname_strict_subdomain_c(ns->rk.dname, iq->dp->name) 
                        || !dname_subdomain_c(iq->qchase.qname, ns->rk.dname)){
                        verbose(VERB_ALGO, "bad referral, throwaway");
                        type = RESPONSE_TYPE_THROWAWAY;
                } else
                        iter_scrub_ds(iq->response, ns, iq->dp->name);
        } else iter_scrub_ds(iq->response, NULL, NULL);

        /* handle each of the type cases */
        if(type == RESPONSE_TYPE_ANSWER) {
                /* ANSWER type responses terminate the query algorithm, 
                 * so they sent on their */
                if(verbosity >= VERB_DETAIL) {
                        verbose(VERB_DETAIL, "query response was %s",
                                FLAGS_GET_RCODE(iq->response->rep->flags)
                                ==LDNS_RCODE_NXDOMAIN?"NXDOMAIN ANSWER":
                                (iq->response->rep->an_numrrsets?"ANSWER":
                                "nodata ANSWER"));
                }
                /* if qtype is DS, check we have the right level of answer,
                 * like grandchild answer but we need the middle, reject it */
                if(iq->qchase.qtype == LDNS_RR_TYPE_DS && !iq->dsns_point
                        && !(iq->chase_flags&BIT_RD)
                        && iter_ds_toolow(iq->response, iq->dp)
                        && iter_dp_cangodown(&iq->qchase, iq->dp)) {
                        /* close down outstanding requests to be discarded */
                        outbound_list_clear(&iq->outlist);
                        iq->num_current_queries = 0;
                        fptr_ok(fptr_whitelist_modenv_detach_subs(
                                qstate->env->detach_subs));
                        (*qstate->env->detach_subs)(qstate);
                        iq->num_target_queries = 0;
                        return processDSNSFind(qstate, iq, id);
                }
                iter_dns_store(qstate->env, &iq->response->qinfo,
                        iq->response->rep, 0, qstate->prefetch_leeway,
                        iq->dp&&iq->dp->has_parent_side_NS,
                        qstate->region, qstate->query_flags);
                /* close down outstanding requests to be discarded */
                outbound_list_clear(&iq->outlist);
                iq->num_current_queries = 0;
                fptr_ok(fptr_whitelist_modenv_detach_subs(
                        qstate->env->detach_subs));
                (*qstate->env->detach_subs)(qstate);
                iq->num_target_queries = 0;
                if(qstate->reply)
                        sock_list_insert(&qstate->reply_origin, 
                                &qstate->reply->addr, qstate->reply->addrlen, 
                                qstate->region);
                return final_state(iq);
        } else if(type == RESPONSE_TYPE_REFERRAL) {
                /* REFERRAL type responses get a reset of the 
                 * delegation point, and back to the QUERYTARGETS_STATE. */
                verbose(VERB_DETAIL, "query response was REFERRAL");

                /* if hardened, only store referral if we asked for it */
                if(!qstate->env->cfg->harden_referral_path ||
                    (  qstate->qinfo.qtype == LDNS_RR_TYPE_NS 
                        && (qstate->query_flags&BIT_RD) 
                        && !(qstate->query_flags&BIT_CD)
                           /* we know that all other NS rrsets are scrubbed
                            * away, thus on referral only one is left.
                            * see if that equals the query name... */
                        && ( /* auth section, but sometimes in answer section*/
                          reply_find_rrset_section_ns(iq->response->rep,
                                iq->qchase.qname, iq->qchase.qname_len,
                                LDNS_RR_TYPE_NS, iq->qchase.qclass)
                          || reply_find_rrset_section_an(iq->response->rep,
                                iq->qchase.qname, iq->qchase.qname_len,
                                LDNS_RR_TYPE_NS, iq->qchase.qclass)
                          )
                    )) {
                        /* Store the referral under the current query */
                        /* no prefetch-leeway, since its not the answer */
                        iter_dns_store(qstate->env, &iq->response->qinfo,
                                iq->response->rep, 1, 0, 0, NULL, 0);
                        if(iq->store_parent_NS)
                                iter_store_parentside_NS(qstate->env, 
                                        iq->response->rep);
                        if(qstate->env->neg_cache)
                                val_neg_addreferral(qstate->env->neg_cache, 
                                        iq->response->rep, iq->dp->name);
                }
                /* store parent-side-in-zone-glue, if directly queried for */
                if(iq->query_for_pside_glue && !iq->pside_glue) {
                        iq->pside_glue = reply_find_rrset(iq->response->rep, 
                                iq->qchase.qname, iq->qchase.qname_len, 
                                iq->qchase.qtype, iq->qchase.qclass);
                        if(iq->pside_glue) {
                                log_rrset_key(VERB_ALGO, "found parent-side "
                                        "glue", iq->pside_glue);
                                iter_store_parentside_rrset(qstate->env,
                                        iq->pside_glue);
                        }
                }

                /* Reset the event state, setting the current delegation 
                 * point to the referral. */
                iq->deleg_msg = iq->response;
                iq->dp = delegpt_from_message(iq->response, qstate->region);
                if(!iq->dp)
                        return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                if(!cache_fill_missing(qstate->env, iq->qchase.qclass, 
                        qstate->region, iq->dp))
                        return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                if(iq->store_parent_NS && query_dname_compare(iq->dp->name,
                        iq->store_parent_NS->name) == 0)
                        iter_merge_retry_counts(iq->dp, iq->store_parent_NS);
                delegpt_log(VERB_ALGO, iq->dp);
                /* Count this as a referral. */
                iq->referral_count++;
                iq->sent_count = 0;
                /* see if the next dp is a trust anchor, or a DS was sent
                 * along, indicating dnssec is expected for next zone */
                iq->dnssec_expected = iter_indicates_dnssec(qstate->env, 
                        iq->dp, iq->response, iq->qchase.qclass);
                /* if dnssec, validating then also fetch the key for the DS */
                if(iq->dnssec_expected && qstate->env->cfg->prefetch_key &&
                        !(qstate->query_flags&BIT_CD))
                        generate_dnskey_prefetch(qstate, iq, id);

                /* spawn off NS and addr to auth servers for the NS we just
                 * got in the referral. This gets authoritative answer
                 * (answer section trust level) rrset. 
                 * right after, we detach the subs, answer goes to cache. */
                if(qstate->env->cfg->harden_referral_path)
                        generate_ns_check(qstate, iq, id);

                /* stop current outstanding queries. 
                 * FIXME: should the outstanding queries be waited for and
                 * handled? Say by a subquery that inherits the outbound_entry.
                 */
                outbound_list_clear(&iq->outlist);
                iq->num_current_queries = 0;
                fptr_ok(fptr_whitelist_modenv_detach_subs(
                        qstate->env->detach_subs));
                (*qstate->env->detach_subs)(qstate);
                iq->num_target_queries = 0;
                verbose(VERB_ALGO, "cleared outbound list for next round");
                return next_state(iq, QUERYTARGETS_STATE);
        } else if(type == RESPONSE_TYPE_CNAME) {
                uint8_t* sname = NULL;
                size_t snamelen = 0;
                /* CNAME type responses get a query restart (i.e., get a 
                 * reset of the query state and go back to INIT_REQUEST_STATE).
                 */
                verbose(VERB_DETAIL, "query response was CNAME");
                if(verbosity >= VERB_ALGO)
                        log_dns_msg("cname msg", &iq->response->qinfo, 
                                iq->response->rep);
                /* if qtype is DS, check we have the right level of answer,
                 * like grandchild answer but we need the middle, reject it */
                if(iq->qchase.qtype == LDNS_RR_TYPE_DS && !iq->dsns_point
                        && !(iq->chase_flags&BIT_RD)
                        && iter_ds_toolow(iq->response, iq->dp)
                        && iter_dp_cangodown(&iq->qchase, iq->dp)) {
                        outbound_list_clear(&iq->outlist);
                        iq->num_current_queries = 0;
                        fptr_ok(fptr_whitelist_modenv_detach_subs(
                                qstate->env->detach_subs));
                        (*qstate->env->detach_subs)(qstate);
                        iq->num_target_queries = 0;
                        return processDSNSFind(qstate, iq, id);
                }
                /* Process the CNAME response. */
                if(!handle_cname_response(qstate, iq, iq->response, 
                        &sname, &snamelen))
                        return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                /* cache the CNAME response under the current query */
                /* NOTE : set referral=1, so that rrsets get stored but not 
                 * the partial query answer (CNAME only). */
                /* prefetchleeway applied because this updates answer parts */
                iter_dns_store(qstate->env, &iq->response->qinfo,
                        iq->response->rep, 1, qstate->prefetch_leeway,
                        iq->dp&&iq->dp->has_parent_side_NS, NULL,
                        qstate->query_flags);
                /* set the current request's qname to the new value. */
                iq->qchase.qname = sname;
                iq->qchase.qname_len = snamelen;
                /* Clear the query state, since this is a query restart. */
                iq->deleg_msg = NULL;
                iq->dp = NULL;
                iq->dsns_point = NULL;
                /* Note the query restart. */
                iq->query_restart_count++;
                iq->sent_count = 0;

                /* stop current outstanding queries. 
                 * FIXME: should the outstanding queries be waited for and
                 * handled? Say by a subquery that inherits the outbound_entry.
                 */
                outbound_list_clear(&iq->outlist);
                iq->num_current_queries = 0;
                fptr_ok(fptr_whitelist_modenv_detach_subs(
                        qstate->env->detach_subs));
                (*qstate->env->detach_subs)(qstate);
                iq->num_target_queries = 0;
                if(qstate->reply)
                        sock_list_insert(&qstate->reply_origin, 
                                &qstate->reply->addr, qstate->reply->addrlen, 
                                qstate->region);
                verbose(VERB_ALGO, "cleared outbound list for query restart");
                /* go to INIT_REQUEST_STATE for new qname. */
                return next_state(iq, INIT_REQUEST_STATE);
        } else if(type == RESPONSE_TYPE_LAME) {
                /* Cache the LAMEness. */
                verbose(VERB_DETAIL, "query response was %sLAME",
                        dnsseclame?"DNSSEC ":"");
                if(!dname_subdomain_c(iq->qchase.qname, iq->dp->name)) {
                        log_err("mark lame: mismatch in qname and dpname");
                        /* throwaway this reply below */
                } else if(qstate->reply) {
                        /* need addr for lameness cache, but we may have
                         * gotten this from cache, so test to be sure */
                        if(!infra_set_lame(qstate->env->infra_cache, 
                                &qstate->reply->addr, qstate->reply->addrlen, 
                                iq->dp->name, iq->dp->namelen, 
                                *qstate->env->now, dnsseclame, 0,
                                iq->qchase.qtype))
                                log_err("mark host lame: out of memory");
                }
        } else if(type == RESPONSE_TYPE_REC_LAME) {
                /* Cache the LAMEness. */
                verbose(VERB_DETAIL, "query response REC_LAME: "
                        "recursive but not authoritative server");
                if(!dname_subdomain_c(iq->qchase.qname, iq->dp->name)) {
                        log_err("mark rec_lame: mismatch in qname and dpname");
                        /* throwaway this reply below */
                } else if(qstate->reply) {
                        /* need addr for lameness cache, but we may have
                         * gotten this from cache, so test to be sure */
                        verbose(VERB_DETAIL, "mark as REC_LAME");
                        if(!infra_set_lame(qstate->env->infra_cache, 
                                &qstate->reply->addr, qstate->reply->addrlen, 
                                iq->dp->name, iq->dp->namelen, 
                                *qstate->env->now, 0, 1, iq->qchase.qtype))
                                log_err("mark host lame: out of memory");
                } 
        } else if(type == RESPONSE_TYPE_THROWAWAY) {
                /* LAME and THROWAWAY responses are handled the same way. 
                 * In this case, the event is just sent directly back to 
                 * the QUERYTARGETS_STATE without resetting anything, 
                 * because, clearly, the next target must be tried. */
                verbose(VERB_DETAIL, "query response was THROWAWAY");
        } else {
                log_warn("A query response came back with an unknown type: %d",
                        (int)type);
        }

        /* LAME, THROWAWAY and "unknown" all end up here.
         * Recycle to the QUERYTARGETS state to hopefully try a 
         * different target. */
        return next_state(iq, QUERYTARGETS_STATE);
}

/**
 * Return priming query results to interested super querystates.
 * 
 * Sets the delegation point and delegation message (not nonRD queries).
 * This is a callback from walk_supers.
 *
 * @param qstate: priming query state that finished.
 * @param id: module id.
 * @param forq: the qstate for which priming has been done.
 */
static void
prime_supers(struct module_qstate* qstate, int id, struct module_qstate* forq)
{
        struct iter_qstate* foriq = (struct iter_qstate*)forq->minfo[id];
        struct delegpt* dp = NULL;

        log_assert(qstate->is_priming || foriq->wait_priming_stub);
        log_assert(qstate->return_rcode == LDNS_RCODE_NOERROR);
        /* Convert our response to a delegation point */
        dp = delegpt_from_message(qstate->return_msg, forq->region);
        if(!dp) {
                /* if there is no convertable delegation point, then 
                 * the ANSWER type was (presumably) a negative answer. */
                verbose(VERB_ALGO, "prime response was not a positive "
                        "ANSWER; failing");
                foriq->dp = NULL;
                foriq->state = QUERYTARGETS_STATE;
                return;
        }

        log_query_info(VERB_DETAIL, "priming successful for", &qstate->qinfo);
        delegpt_log(VERB_ALGO, dp);
        foriq->dp = dp;
        foriq->deleg_msg = dns_copy_msg(qstate->return_msg, forq->region);
        if(!foriq->deleg_msg) {
                log_err("copy prime response: out of memory");
                foriq->dp = NULL;
                foriq->state = QUERYTARGETS_STATE;
                return;
        }

        /* root priming responses go to init stage 2, priming stub 
         * responses to to stage 3. */
        if(foriq->wait_priming_stub) {
                foriq->state = INIT_REQUEST_3_STATE;
                foriq->wait_priming_stub = 0;
        } else  foriq->state = INIT_REQUEST_2_STATE;
        /* because we are finished, the parent will be reactivated */
}

/** 
 * This handles the response to a priming query. This is used to handle both
 * root and stub priming responses. This is basically the equivalent of the
 * QUERY_RESP_STATE, but will not handle CNAME responses and will treat
 * REFERRALs as ANSWERS. It will also update and reactivate the originating
 * event.
 *
 * @param qstate: query state.
 * @param id: module id.
 * @return true if the event needs more immediate processing, false if not.
 *         This state always returns false.
 */
static int
processPrimeResponse(struct module_qstate* qstate, int id)
{
        struct iter_qstate* iq = (struct iter_qstate*)qstate->minfo[id];
        enum response_type type;
        iq->response->rep->flags &= ~(BIT_RD|BIT_RA); /* ignore rec-lame */
        type = response_type_from_server(
                (int)((iq->chase_flags&BIT_RD) || iq->chase_to_rd), 
                iq->response, &iq->qchase, iq->dp);
        if(type == RESPONSE_TYPE_ANSWER) {
                qstate->return_rcode = LDNS_RCODE_NOERROR;
                qstate->return_msg = iq->response;
        } else {
                qstate->return_rcode = LDNS_RCODE_SERVFAIL;
                qstate->return_msg = NULL;
        }

        /* validate the root or stub after priming (if enabled).
         * This is the same query as the prime query, but with validation.
         * Now that we are primed, the additional queries that validation
         * may need can be resolved, such as DLV. */
        if(qstate->env->cfg->harden_referral_path) {
                struct module_qstate* subq = NULL;
                log_nametypeclass(VERB_ALGO, "schedule prime validation", 
                        qstate->qinfo.qname, qstate->qinfo.qtype,
                        qstate->qinfo.qclass);
                if(!generate_sub_request(qstate->qinfo.qname, 
                        qstate->qinfo.qname_len, qstate->qinfo.qtype,
                        qstate->qinfo.qclass, qstate, id, iq,
                        INIT_REQUEST_STATE, FINISHED_STATE, &subq, 1)) {
                        verbose(VERB_ALGO, "could not generate prime check");
                }
                generate_a_aaaa_check(qstate, iq, id);
        }

        /* This event is finished. */
        qstate->ext_state[id] = module_finished;
        return 0;
}

/** 
 * Do final processing on responses to target queries. Events reach this
 * state after the iterative resolution algorithm terminates. This state is
 * responsible for reactiving the original event, and housekeeping related
 * to received target responses (caching, updating the current delegation
 * point, etc).
 * Callback from walk_supers for every super state that is interested in 
 * the results from this query.
 *
 * @param qstate: query state.
 * @param id: module id.
 * @param forq: super query state.
 */
static void
processTargetResponse(struct module_qstate* qstate, int id,
        struct module_qstate* forq)
{
        struct iter_qstate* iq = (struct iter_qstate*)qstate->minfo[id];
        struct iter_qstate* foriq = (struct iter_qstate*)forq->minfo[id];
        struct ub_packed_rrset_key* rrset;
        struct delegpt_ns* dpns;
        log_assert(qstate->return_rcode == LDNS_RCODE_NOERROR);

        foriq->state = QUERYTARGETS_STATE;
        log_query_info(VERB_ALGO, "processTargetResponse", &qstate->qinfo);
        log_query_info(VERB_ALGO, "processTargetResponse super", &forq->qinfo);

        /* check to see if parent event is still interested (in orig name).  */
        if(!foriq->dp) {
                verbose(VERB_ALGO, "subq: parent not interested, was reset");
                return; /* not interested anymore */
        }
        dpns = delegpt_find_ns(foriq->dp, qstate->qinfo.qname,
                        qstate->qinfo.qname_len);
        if(!dpns) {
                /* If not interested, just stop processing this event */
                verbose(VERB_ALGO, "subq: parent not interested anymore");
                /* could be because parent was jostled out of the cache,
                   and a new identical query arrived, that does not want it*/
                return;
        }

        /* Tell the originating event that this target query has finished
         * (regardless if it succeeded or not). */
        foriq->num_target_queries--;

        /* if iq->query_for_pside_glue then add the pside_glue (marked lame) */
        if(iq->pside_glue) {
                /* if the pside_glue is NULL, then it could not be found,
                 * the done_pside is already set when created and a cache
                 * entry created in processFinished so nothing to do here */
                log_rrset_key(VERB_ALGO, "add parentside glue to dp", 
                        iq->pside_glue);
                if(!delegpt_add_rrset(foriq->dp, forq->region, 
                        iq->pside_glue, 1))
                        log_err("out of memory adding pside glue");
        }

        /* This response is relevant to the current query, so we 
         * add (attempt to add, anyway) this target(s) and reactivate 
         * the original event. 
         * NOTE: we could only look for the AnswerRRset if the 
         * response type was ANSWER. */
        rrset = reply_find_answer_rrset(&iq->qchase, qstate->return_msg->rep);
        if(rrset) {
                /* if CNAMEs have been followed - add new NS to delegpt. */
                /* BTW. RFC 1918 says NS should not have got CNAMEs. Robust. */
                if(!delegpt_find_ns(foriq->dp, rrset->rk.dname, 
                        rrset->rk.dname_len)) {
                        /* if dpns->lame then set newcname ns lame too */
                        if(!delegpt_add_ns(foriq->dp, forq->region, 
                                rrset->rk.dname, dpns->lame))
                                log_err("out of memory adding cnamed-ns");
                }
                /* if dpns->lame then set the address(es) lame too */
                if(!delegpt_add_rrset(foriq->dp, forq->region, rrset, 
                        dpns->lame))
                        log_err("out of memory adding targets");
                verbose(VERB_ALGO, "added target response");
                delegpt_log(VERB_ALGO, foriq->dp);
        } else {
                verbose(VERB_ALGO, "iterator TargetResponse failed");
                dpns->resolved = 1; /* fail the target */
        }
}

/**
 * Process response for DS NS Find queries, that attempt to find the delegation
 * point where we ask the DS query from.
 *
 * @param qstate: query state.
 * @param id: module id.
 * @param forq: super query state.
 */
static void
processDSNSResponse(struct module_qstate* qstate, int id,
        struct module_qstate* forq)
{
        struct iter_qstate* foriq = (struct iter_qstate*)forq->minfo[id];

        /* if the finished (iq->response) query has no NS set: continue
         * up to look for the right dp; nothing to change, do DPNSstate */
        if(qstate->return_rcode != LDNS_RCODE_NOERROR)
                return; /* seek further */
        /* find the NS RRset (without allowing CNAMEs) */
        if(!reply_find_rrset(qstate->return_msg->rep, qstate->qinfo.qname,
                qstate->qinfo.qname_len, LDNS_RR_TYPE_NS,
                qstate->qinfo.qclass)){
                return; /* seek further */
        }

        /* else, store as DP and continue at querytargets */
        foriq->state = QUERYTARGETS_STATE;
        foriq->dp = delegpt_from_message(qstate->return_msg, forq->region);
        if(!foriq->dp) {
                log_err("out of memory in dsns dp alloc");
                return; /* dp==NULL in QUERYTARGETS makes SERVFAIL */
        }
        /* success, go query the querytargets in the new dp (and go down) */
}

/**
 * Process response for qclass=ANY queries for a particular class.
 * Append to result or error-exit.
 *
 * @param qstate: query state.
 * @param id: module id.
 * @param forq: super query state.
 */
static void
processClassResponse(struct module_qstate* qstate, int id,
        struct module_qstate* forq)
{
        struct iter_qstate* foriq = (struct iter_qstate*)forq->minfo[id];
        struct dns_msg* from = qstate->return_msg;
        log_query_info(VERB_ALGO, "processClassResponse", &qstate->qinfo);
        log_query_info(VERB_ALGO, "processClassResponse super", &forq->qinfo);
        if(qstate->return_rcode != LDNS_RCODE_NOERROR) {
                /* cause servfail for qclass ANY query */
                foriq->response = NULL;
                foriq->state = FINISHED_STATE;
                return;
        }
        /* append result */
        if(!foriq->response) {
                /* allocate the response: copy RCODE, sec_state */
                foriq->response = dns_copy_msg(from, forq->region);
                if(!foriq->response) {
                        log_err("malloc failed for qclass ANY response"); 
                        foriq->state = FINISHED_STATE;
                        return;
                }
                foriq->response->qinfo.qclass = forq->qinfo.qclass;
                /* qclass ANY does not receive the AA flag on replies */
                foriq->response->rep->authoritative = 0; 
        } else {
                struct dns_msg* to = foriq->response;
                /* add _from_ this response _to_ existing collection */
                /* if there are records, copy RCODE */
                /* lower sec_state if this message is lower */
                if(from->rep->rrset_count != 0) {
                        size_t n = from->rep->rrset_count+to->rep->rrset_count;
                        struct ub_packed_rrset_key** dest, **d;
                        /* copy appropriate rcode */
                        to->rep->flags = from->rep->flags;
                        /* copy rrsets */
                        dest = regional_alloc(forq->region, sizeof(dest[0])*n);
                        if(!dest) {
                                log_err("malloc failed in collect ANY"); 
                                foriq->state = FINISHED_STATE;
                                return;
                        }
                        d = dest;
                        /* copy AN */
                        memcpy(dest, to->rep->rrsets, to->rep->an_numrrsets
                                * sizeof(dest[0]));
                        dest += to->rep->an_numrrsets;
                        memcpy(dest, from->rep->rrsets, from->rep->an_numrrsets
                                * sizeof(dest[0]));
                        dest += from->rep->an_numrrsets;
                        /* copy NS */
                        memcpy(dest, to->rep->rrsets+to->rep->an_numrrsets,
                                to->rep->ns_numrrsets * sizeof(dest[0]));
                        dest += to->rep->ns_numrrsets;
                        memcpy(dest, from->rep->rrsets+from->rep->an_numrrsets,
                                from->rep->ns_numrrsets * sizeof(dest[0]));
                        dest += from->rep->ns_numrrsets;
                        /* copy AR */
                        memcpy(dest, to->rep->rrsets+to->rep->an_numrrsets+
                                to->rep->ns_numrrsets,
                                to->rep->ar_numrrsets * sizeof(dest[0]));
                        dest += to->rep->ar_numrrsets;
                        memcpy(dest, from->rep->rrsets+from->rep->an_numrrsets+
                                from->rep->ns_numrrsets,
                                from->rep->ar_numrrsets * sizeof(dest[0]));
                        /* update counts */
                        to->rep->rrsets = d;
                        to->rep->an_numrrsets += from->rep->an_numrrsets;
                        to->rep->ns_numrrsets += from->rep->ns_numrrsets;
                        to->rep->ar_numrrsets += from->rep->ar_numrrsets;
                        to->rep->rrset_count = n;
                }
                if(from->rep->security < to->rep->security) /* lowest sec */
                        to->rep->security = from->rep->security;
                if(from->rep->qdcount != 0) /* insert qd if appropriate */
                        to->rep->qdcount = from->rep->qdcount;
                if(from->rep->ttl < to->rep->ttl) /* use smallest TTL */
                        to->rep->ttl = from->rep->ttl;
                if(from->rep->prefetch_ttl < to->rep->prefetch_ttl)
                        to->rep->prefetch_ttl = from->rep->prefetch_ttl;
        }
        /* are we done? */
        foriq->num_current_queries --;
        if(foriq->num_current_queries == 0)
                foriq->state = FINISHED_STATE;
}
        
/** 
 * Collect class ANY responses and make them into one response.  This
 * state is started and it creates queries for all classes (that have
 * root hints).  The answers are then collected.
 *
 * @param qstate: query state.
 * @param id: module id.
 * @return true if the event needs more immediate processing, false if not.
 */
static int
processCollectClass(struct module_qstate* qstate, int id)
{
        struct iter_qstate* iq = (struct iter_qstate*)qstate->minfo[id];
        struct module_qstate* subq;
        /* If qchase.qclass == 0 then send out queries for all classes.
         * Otherwise, do nothing (wait for all answers to arrive and the
         * processClassResponse to put them together, and that moves us
         * towards the Finished state when done. */
        if(iq->qchase.qclass == 0) {
                uint16_t c = 0;
                iq->qchase.qclass = LDNS_RR_CLASS_ANY;
                while(iter_get_next_root(qstate->env->hints,
                        qstate->env->fwds, &c)) {
                        /* generate query for this class */
                        log_nametypeclass(VERB_ALGO, "spawn collect query",
                                qstate->qinfo.qname, qstate->qinfo.qtype, c);
                        if(!generate_sub_request(qstate->qinfo.qname,
                                qstate->qinfo.qname_len, qstate->qinfo.qtype,
                                c, qstate, id, iq, INIT_REQUEST_STATE,
                                FINISHED_STATE, &subq, 
                                (int)!(qstate->query_flags&BIT_CD))) {
                                return error_response(qstate, id, 
                                        LDNS_RCODE_SERVFAIL);
                        }
                        /* ignore subq, no special init required */
                        iq->num_current_queries ++;
                        if(c == 0xffff)
                                break;
                        else c++;
                }
                /* if no roots are configured at all, return */
                if(iq->num_current_queries == 0) {
                        verbose(VERB_ALGO, "No root hints or fwds, giving up "
                                "on qclass ANY");
                        return error_response(qstate, id, LDNS_RCODE_REFUSED);
                }
                /* return false, wait for queries to return */
        }
        /* if woke up here because of an answer, wait for more answers */
        return 0;
}

/** 
 * This handles the final state for first-tier responses (i.e., responses to
 * externally generated queries).
 *
 * @param qstate: query state.
 * @param iq: iterator query state.
 * @param id: module id.
 * @return true if the event needs more processing, false if not. Since this
 *         is the final state for an event, it always returns false.
 */
static int
processFinished(struct module_qstate* qstate, struct iter_qstate* iq,
        int id)
{
        log_query_info(VERB_QUERY, "finishing processing for", 
                &qstate->qinfo);

        /* store negative cache element for parent side glue. */
        if(iq->query_for_pside_glue && !iq->pside_glue)
                iter_store_parentside_neg(qstate->env, &qstate->qinfo,
                        iq->deleg_msg?iq->deleg_msg->rep:
                        (iq->response?iq->response->rep:NULL));
        if(!iq->response) {
                verbose(VERB_ALGO, "No response is set, servfail");
                return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
        }

        /* Make sure that the RA flag is set (since the presence of 
         * this module means that recursion is available) */
        iq->response->rep->flags |= BIT_RA;

        /* Clear the AA flag */
        /* FIXME: does this action go here or in some other module? */
        iq->response->rep->flags &= ~BIT_AA;

        /* make sure QR flag is on */
        iq->response->rep->flags |= BIT_QR;

        /* we have finished processing this query */
        qstate->ext_state[id] = module_finished;

        /* TODO:  we are using a private TTL, trim the response. */
        /* if (mPrivateTTL > 0){IterUtils.setPrivateTTL(resp, mPrivateTTL); } */

        /* prepend any items we have accumulated */
        if(iq->an_prepend_list || iq->ns_prepend_list) {
                if(!iter_prepend(iq, iq->response, qstate->region)) {
                        log_err("prepend rrsets: out of memory");
                        return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                }
                /* reset the query name back */
                iq->response->qinfo = qstate->qinfo;
                /* the security state depends on the combination */
                iq->response->rep->security = sec_status_unchecked;
                /* store message with the finished prepended items,
                 * but only if we did recursion. The nonrecursion referral
                 * from cache does not need to be stored in the msg cache. */
                if(qstate->query_flags&BIT_RD) {
                        iter_dns_store(qstate->env, &qstate->qinfo, 
                                iq->response->rep, 0, qstate->prefetch_leeway,
                                iq->dp&&iq->dp->has_parent_side_NS,
                                qstate->region, qstate->query_flags);
                }
        }
        qstate->return_rcode = LDNS_RCODE_NOERROR;
        qstate->return_msg = iq->response;
        return 0;
}

/*
 * Return priming query results to interestes super querystates.
 * 
 * Sets the delegation point and delegation message (not nonRD queries).
 * This is a callback from walk_supers.
 *
 * @param qstate: query state that finished.
 * @param id: module id.
 * @param super: the qstate to inform.
 */
void
iter_inform_super(struct module_qstate* qstate, int id, 
        struct module_qstate* super)
{
        if(!qstate->is_priming && super->qinfo.qclass == LDNS_RR_CLASS_ANY)
                processClassResponse(qstate, id, super);
        else if(super->qinfo.qtype == LDNS_RR_TYPE_DS && ((struct iter_qstate*)
                super->minfo[id])->state == DSNS_FIND_STATE)
                processDSNSResponse(qstate, id, super);
        else if(qstate->return_rcode != LDNS_RCODE_NOERROR)
                error_supers(qstate, id, super);
        else if(qstate->is_priming)
                prime_supers(qstate, id, super);
        else    processTargetResponse(qstate, id, super);
}

/**
 * Handle iterator state.
 * Handle events. This is the real processing loop for events, responsible
 * for moving events through the various states. If a processing method
 * returns true, then it will be advanced to the next state. If false, then
 * processing will stop.
 *
 * @param qstate: query state.
 * @param ie: iterator shared global environment.
 * @param iq: iterator query state.
 * @param id: module id.
 */
static void
iter_handle(struct module_qstate* qstate, struct iter_qstate* iq,
        struct iter_env* ie, int id)
{
        int cont = 1;
        while(cont) {
                verbose(VERB_ALGO, "iter_handle processing q with state %s",
                        iter_state_to_string(iq->state));
                switch(iq->state) {
                        case INIT_REQUEST_STATE:
                                cont = processInitRequest(qstate, iq, ie, id);
                                break;
                        case INIT_REQUEST_2_STATE:
                                cont = processInitRequest2(qstate, iq, id);
                                break;
                        case INIT_REQUEST_3_STATE:
                                cont = processInitRequest3(qstate, iq, id);
                                break;
                        case QUERYTARGETS_STATE:
                                cont = processQueryTargets(qstate, iq, ie, id);
                                break;
                        case QUERY_RESP_STATE:
                                cont = processQueryResponse(qstate, iq, id);
                                break;
                        case PRIME_RESP_STATE:
                                cont = processPrimeResponse(qstate, id);
                                break;
                        case COLLECT_CLASS_STATE:
                                cont = processCollectClass(qstate, id);
                                break;
                        case DSNS_FIND_STATE:
                                cont = processDSNSFind(qstate, iq, id);
                                break;
                        case FINISHED_STATE:
                                cont = processFinished(qstate, iq, id);
                                break;
                        default:
                                log_warn("iterator: invalid state: %d",
                                        iq->state);
                                cont = 0;
                                break;
                }
        }
}

/** 
 * This is the primary entry point for processing request events. Note that
 * this method should only be used by external modules.
 * @param qstate: query state.
 * @param ie: iterator shared global environment.
 * @param iq: iterator query state.
 * @param id: module id.
 */
static void
process_request(struct module_qstate* qstate, struct iter_qstate* iq,
        struct iter_env* ie, int id)
{
        /* external requests start in the INIT state, and finish using the
         * FINISHED state. */
        iq->state = INIT_REQUEST_STATE;
        iq->final_state = FINISHED_STATE;
        verbose(VERB_ALGO, "process_request: new external request event");
        iter_handle(qstate, iq, ie, id);
}

/** process authoritative server reply */
static void
process_response(struct module_qstate* qstate, struct iter_qstate* iq, 
        struct iter_env* ie, int id, struct outbound_entry* outbound,
        enum module_ev event)
{
        struct msg_parse* prs;
        struct edns_data edns;
        sldns_buffer* pkt;

        verbose(VERB_ALGO, "process_response: new external response event");
        iq->response = NULL;
        iq->state = QUERY_RESP_STATE;
        if(event == module_event_noreply || event == module_event_error) {
                if(event == module_event_noreply && iq->sent_count >= 3 &&
                        qstate->env->cfg->use_caps_bits_for_id &&
                        !iq->caps_fallback) {
                        /* start fallback */
                        iq->caps_fallback = 1;
                        iq->caps_server = 0;
                        iq->caps_reply = NULL;
                        iq->state = QUERYTARGETS_STATE;
                        iq->num_current_queries--;
                        /* need fresh attempts for the 0x20 fallback, if
                         * that was the cause for the failure */
                        iter_dec_attempts(iq->dp, 3);
                        verbose(VERB_DETAIL, "Capsforid: timeouts, starting fallback");
                        goto handle_it;
                }
                goto handle_it;
        }
        if( (event != module_event_reply && event != module_event_capsfail)
                || !qstate->reply) {
                log_err("Bad event combined with response");
                outbound_list_remove(&iq->outlist, outbound);
                (void)error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                return;
        }

        /* parse message */
        prs = (struct msg_parse*)regional_alloc(qstate->env->scratch, 
                sizeof(struct msg_parse));
        if(!prs) {
                log_err("out of memory on incoming message");
                /* like packet got dropped */
                goto handle_it;
        }
        memset(prs, 0, sizeof(*prs));
        memset(&edns, 0, sizeof(edns));
        pkt = qstate->reply->c->buffer;
        sldns_buffer_set_position(pkt, 0);
        if(parse_packet(pkt, prs, qstate->env->scratch) != LDNS_RCODE_NOERROR) {
                verbose(VERB_ALGO, "parse error on reply packet");
                goto handle_it;
        }
        /* edns is not examined, but removed from message to help cache */
        if(parse_extract_edns(prs, &edns) != LDNS_RCODE_NOERROR)
                goto handle_it;
        /* remove CD-bit, we asked for in case we handle validation ourself */
        prs->flags &= ~BIT_CD;

        /* normalize and sanitize: easy to delete items from linked lists */
        if(!scrub_message(pkt, prs, &iq->qchase, iq->dp->name, 
                qstate->env->scratch, qstate->env, ie))
                goto handle_it;

        /* allocate response dns_msg in region */
        iq->response = dns_alloc_msg(pkt, prs, qstate->region);
        if(!iq->response)
                goto handle_it;
        log_query_info(VERB_DETAIL, "response for", &qstate->qinfo);
        log_name_addr(VERB_DETAIL, "reply from", iq->dp->name, 
                &qstate->reply->addr, qstate->reply->addrlen);
        if(verbosity >= VERB_ALGO)
                log_dns_msg("incoming scrubbed packet:", &iq->response->qinfo, 
                        iq->response->rep);
        
        if(event == module_event_capsfail || iq->caps_fallback) {
                if(!iq->caps_fallback) {
                        /* start fallback */
                        iq->caps_fallback = 1;
                        iq->caps_server = 0;
                        iq->caps_reply = iq->response->rep;
                        iq->state = QUERYTARGETS_STATE;
                        iq->num_current_queries--;
                        verbose(VERB_DETAIL, "Capsforid: starting fallback");
                        goto handle_it;
                } else {
                        /* check if reply is the same, otherwise, fail */
                        if(!iq->caps_reply) {
                                iq->caps_reply = iq->response->rep;
                                iq->caps_server = -1; /*become zero at ++,
                                so that we start the full set of trials */
                        } else if(!reply_equal(iq->response->rep, iq->caps_reply,
                                qstate->env->scratch)) {
                                verbose(VERB_DETAIL, "Capsforid fallback: "
                                        "getting different replies, failed");
                                outbound_list_remove(&iq->outlist, outbound);
                                (void)error_response(qstate, id, 
                                        LDNS_RCODE_SERVFAIL);
                                return;
                        }
                        /* continue the fallback procedure at next server */
                        iq->caps_server++;
                        iq->state = QUERYTARGETS_STATE;
                        iq->num_current_queries--;
                        verbose(VERB_DETAIL, "Capsforid: reply is equal. "
                                "go to next fallback");
                        goto handle_it;
                }
        }
        iq->caps_fallback = 0; /* if we were in fallback, 0x20 is OK now */

handle_it:
        outbound_list_remove(&iq->outlist, outbound);
        iter_handle(qstate, iq, ie, id);
}

void 
iter_operate(struct module_qstate* qstate, enum module_ev event, int id,
        struct outbound_entry* outbound)
{
        struct iter_env* ie = (struct iter_env*)qstate->env->modinfo[id];
        struct iter_qstate* iq = (struct iter_qstate*)qstate->minfo[id];
        verbose(VERB_QUERY, "iterator[module %d] operate: extstate:%s event:%s", 
                id, strextstate(qstate->ext_state[id]), strmodulevent(event));
        if(iq) log_query_info(VERB_QUERY, "iterator operate: query", 
                &qstate->qinfo);
        if(iq && qstate->qinfo.qname != iq->qchase.qname)
                log_query_info(VERB_QUERY, "iterator operate: chased to", 
                        &iq->qchase);

        /* perform iterator state machine */
        if((event == module_event_new || event == module_event_pass) && 
                iq == NULL) {
                if(!iter_new(qstate, id)) {
                        (void)error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                        return;
                }
                iq = (struct iter_qstate*)qstate->minfo[id];
                process_request(qstate, iq, ie, id);
                return;
        }
        if(iq && event == module_event_pass) {
                iter_handle(qstate, iq, ie, id);
                return;
        }
        if(iq && outbound) {
                process_response(qstate, iq, ie, id, outbound, event);
                return;
        }
        if(event == module_event_error) {
                verbose(VERB_ALGO, "got called with event error, giving up");
                (void)error_response(qstate, id, LDNS_RCODE_SERVFAIL);
                return;
        }

        log_err("bad event for iterator");
        (void)error_response(qstate, id, LDNS_RCODE_SERVFAIL);
}

void 
iter_clear(struct module_qstate* qstate, int id)
{
        struct iter_qstate* iq;
        if(!qstate)
                return;
        iq = (struct iter_qstate*)qstate->minfo[id];
        if(iq) {
                outbound_list_clear(&iq->outlist);
                if(iq->target_count && --iq->target_count[0] == 0)
                        free(iq->target_count);
                iq->num_current_queries = 0;
        }
        qstate->minfo[id] = NULL;
}

size_t 
iter_get_mem(struct module_env* env, int id)
{
        struct iter_env* ie = (struct iter_env*)env->modinfo[id];
        if(!ie)
                return 0;
        return sizeof(*ie) + sizeof(int)*((size_t)ie->max_dependency_depth+1)
                + donotq_get_mem(ie->donotq) + priv_get_mem(ie->priv);
}

/**
 * The iterator function block 
 */
static struct module_func_block iter_block = {
        "iterator",
        &iter_init, &iter_deinit, &iter_operate, &iter_inform_super, 
        &iter_clear, &iter_get_mem
};

struct module_func_block* 
iter_get_funcblock(void)
{
        return &iter_block;
}

const char* 
iter_state_to_string(enum iter_state state)
{
        switch (state)
        {
        case INIT_REQUEST_STATE :
                return "INIT REQUEST STATE";
        case INIT_REQUEST_2_STATE :
                return "INIT REQUEST STATE (stage 2)";
        case INIT_REQUEST_3_STATE:
                return "INIT REQUEST STATE (stage 3)";
        case QUERYTARGETS_STATE :
                return "QUERY TARGETS STATE";
        case PRIME_RESP_STATE :
                return "PRIME RESPONSE STATE";
        case COLLECT_CLASS_STATE :
                return "COLLECT CLASS STATE";
        case DSNS_FIND_STATE :
                return "DSNS FIND STATE";
        case QUERY_RESP_STATE :
                return "QUERY RESPONSE STATE";
        case FINISHED_STATE :
                return "FINISHED RESPONSE STATE";
        default :
                return "UNKNOWN ITER STATE";
        }
}

int 
iter_state_is_responsestate(enum iter_state s)
{
        switch(s) {
                case INIT_REQUEST_STATE :
                case INIT_REQUEST_2_STATE :
                case INIT_REQUEST_3_STATE :
                case QUERYTARGETS_STATE :
                case COLLECT_CLASS_STATE :
                        return 0;
                default:
                        break;
        }
        return 1;
}