/src/unbound/services/mesh.c

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/*
 * services/mesh.c - deal with mesh of query states and handle events for that.
 *
 * 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 functions to assist in dealing with a mesh of
 * query states. This mesh is supposed to be thread-specific.
 * It consists of query states (per qname, qtype, qclass) and connections
 * between query states and the super and subquery states, and replies to
 * send back to clients.
 */
#include "config.h"
#include "services/mesh.h"
#include "services/outbound_list.h"
#include "services/cache/dns.h"
#include "services/cache/rrset.h"
#include "util/log.h"
#include "util/net_help.h"
#include "util/module.h"
#include "util/regional.h"
#include "util/data/msgencode.h"
#include "util/timehist.h"
#include "util/fptr_wlist.h"
#include "util/alloc.h"
#include "util/config_file.h"
#include "util/edns.h"
#include "sldns/sbuffer.h"
#include "sldns/wire2str.h"
#include "services/localzone.h"
#include "util/data/dname.h"
#include "respip/respip.h"
#include "services/listen_dnsport.h"

#ifdef CLIENT_SUBNET
#include "edns-subnet/subnetmod.h"
#include "edns-subnet/edns-subnet.h"
#endif

/** subtract timers and the values do not overflow or become negative */
static void
timeval_subtract(struct timeval* d, const struct timeval* end, const struct timeval* start)
{
#ifndef S_SPLINT_S
  time_t end_usec = end->tv_usec;
  d->tv_sec = end->tv_sec - start->tv_sec;
  if(end_usec < start->tv_usec) {
    end_usec += 1000000;
    d->tv_sec--;
  }
  d->tv_usec = end_usec - start->tv_usec;
#endif
}

/** add timers and the values do not overflow or become negative */
static void
timeval_add(struct timeval* d, const struct timeval* add)
{
#ifndef S_SPLINT_S
  d->tv_sec += add->tv_sec;
  d->tv_usec += add->tv_usec;
  if(d->tv_usec >= 1000000 ) {
    d->tv_usec -= 1000000;
    d->tv_sec++;
  }
#endif
}

/** divide sum of timers to get average */
static void
timeval_divide(struct timeval* avg, const struct timeval* sum, size_t d)
{
#ifndef S_SPLINT_S
  size_t leftover;
  if(d <= 0) {
    avg->tv_sec = 0;
    avg->tv_usec = 0;
    return;
  }
  avg->tv_sec = sum->tv_sec / d;
  avg->tv_usec = sum->tv_usec / d;
  /* handle fraction from seconds divide */
  leftover = sum->tv_sec - avg->tv_sec*d;
  if(leftover <= 0)
    leftover = 0;
  avg->tv_usec += (((long long)leftover)*((long long)1000000))/d;
  if(avg->tv_sec < 0)
    avg->tv_sec = 0;
  if(avg->tv_usec < 0)
    avg->tv_usec = 0;
#endif
}

/** histogram compare of time values */
static int
timeval_smaller(const struct timeval* x, const struct timeval* y)
{
#ifndef S_SPLINT_S
  if(x->tv_sec < y->tv_sec)
    return 1;
  else if(x->tv_sec == y->tv_sec) {
    if(x->tv_usec <= y->tv_usec)
      return 1;
    else  return 0;
  }
  else  return 0;
#endif
}

/**
 * Compare two response-ip client info entries for the purpose of mesh state
 * compare.  It returns 0 if ci_a and ci_b are considered equal; otherwise
 * 1 or -1 (they mean 'ci_a is larger/smaller than ci_b', respectively, but
 * in practice it should be only used to mean they are different).
 * We cannot share the mesh state for two queries if different response-ip
 * actions can apply in the end, even if those queries are otherwise identical.
 * For this purpose we compare tag lists and tag action lists; they should be
 * identical to share the same state.
 * For tag data, we don't look into the data content, as it can be
 * expensive; unless tag data are not defined for both or they point to the
 * exact same data in memory (i.e., they come from the same ACL entry), we
 * consider these data different.
 * Likewise, if the client info is associated with views, we don't look into
 * the views.  They are considered different unless they are exactly the same
 * even if the views only differ in the names.
 */
static int
client_info_compare(const struct respip_client_info* ci_a,
  const struct respip_client_info* ci_b)
{
  int cmp;

  if(!ci_a && !ci_b)
    return 0;
  if(ci_a && !ci_b)
    return -1;
  if(!ci_a && ci_b)
    return 1;
  if(ci_a->taglen != ci_b->taglen)
    return (ci_a->taglen < ci_b->taglen) ? -1 : 1;
  if(ci_a->taglist && !ci_b->taglist)
    return -1;
  if(!ci_a->taglist && ci_b->taglist)
    return 1;
  if(ci_a->taglist && ci_b->taglist) {
    cmp = memcmp(ci_a->taglist, ci_b->taglist, ci_a->taglen);
    if(cmp != 0)
      return cmp;
  }
  if(ci_a->tag_actions_size != ci_b->tag_actions_size)
    return (ci_a->tag_actions_size < ci_b->tag_actions_size) ?
      -1 : 1;
  if(ci_a->tag_actions && !ci_b->tag_actions)
    return -1;
  if(!ci_a->tag_actions && ci_b->tag_actions)
    return 1;
  if(ci_a->tag_actions && ci_b->tag_actions) {
    cmp = memcmp(ci_a->tag_actions, ci_b->tag_actions,
      ci_a->tag_actions_size);
    if(cmp != 0)
      return cmp;
  }
  if(ci_a->tag_datas != ci_b->tag_datas)
    return ci_a->tag_datas < ci_b->tag_datas ? -1 : 1;
  if(ci_a->view != ci_b->view)
    return ci_a->view < ci_b->view ? -1 : 1;
  /* For the unbound daemon these should be non-NULL and identical,
   * but we check that just in case. */
  if(ci_a->respip_set != ci_b->respip_set)
    return ci_a->respip_set < ci_b->respip_set ? -1 : 1;
  return 0;
}

int
mesh_state_compare(const void* ap, const void* bp)
{
  struct mesh_state* a = (struct mesh_state*)ap;
  struct mesh_state* b = (struct mesh_state*)bp;
  int cmp;

  if(a->unique < b->unique)
    return -1;
  if(a->unique > b->unique)
    return 1;

  if(a->s.is_priming && !b->s.is_priming)
    return -1;
  if(!a->s.is_priming && b->s.is_priming)
    return 1;

  if(a->s.is_valrec && !b->s.is_valrec)
    return -1;
  if(!a->s.is_valrec && b->s.is_valrec)
    return 1;

  if((a->s.query_flags&BIT_RD) && !(b->s.query_flags&BIT_RD))
    return -1;
  if(!(a->s.query_flags&BIT_RD) && (b->s.query_flags&BIT_RD))
    return 1;

  if((a->s.query_flags&BIT_CD) && !(b->s.query_flags&BIT_CD))
    return -1;
  if(!(a->s.query_flags&BIT_CD) && (b->s.query_flags&BIT_CD))
    return 1;

  cmp = query_info_compare(&a->s.qinfo, &b->s.qinfo);
  if(cmp != 0)
    return cmp;
  return client_info_compare(a->s.client_info, b->s.client_info);
}

int
mesh_state_ref_compare(const void* ap, const void* bp)
{
  struct mesh_state_ref* a = (struct mesh_state_ref*)ap;
  struct mesh_state_ref* b = (struct mesh_state_ref*)bp;
  return mesh_state_compare(a->s, b->s);
}

struct mesh_area* 
mesh_create(struct module_stack* stack, struct module_env* env)
{
  struct mesh_area* mesh = calloc(1, sizeof(struct mesh_area));
  if(!mesh) {
    log_err("mesh area alloc: out of memory");
    return NULL;
  }
  mesh->histogram = timehist_setup();
  mesh->qbuf_bak = sldns_buffer_new(env->cfg->msg_buffer_size);
  if(!mesh->histogram || !mesh->qbuf_bak) {
    free(mesh);
    log_err("mesh area alloc: out of memory");
    return NULL;
  }
  mesh->mods = *stack;
  mesh->env = env;
  rbtree_init(&mesh->run, &mesh_state_compare);
  rbtree_init(&mesh->all, &mesh_state_compare);
  mesh->num_reply_addrs = 0;
  mesh->num_reply_states = 0;
  mesh->num_detached_states = 0;
  mesh->num_forever_states = 0;
  mesh->stats_jostled = 0;
  mesh->stats_dropped = 0;
  mesh->ans_expired = 0;
  mesh->max_reply_states = env->cfg->num_queries_per_thread;
  mesh->max_forever_states = (mesh->max_reply_states+1)/2;
#ifndef S_SPLINT_S
  mesh->jostle_max.tv_sec = (time_t)(env->cfg->jostle_time / 1000);
  mesh->jostle_max.tv_usec = (time_t)((env->cfg->jostle_time % 1000)
    *1000);
#endif
  return mesh;
}

/** help mesh delete delete mesh states */
static void
mesh_delete_helper(rbnode_type* n)
{
  struct mesh_state* mstate = (struct mesh_state*)n->key;
  /* perform a full delete, not only 'cleanup' routine,
   * because other callbacks expect a clean state in the mesh.
   * For 're-entrant' calls */
  mesh_state_delete(&mstate->s);
  /* but because these delete the items from the tree, postorder
   * traversal and rbtree rebalancing do not work together */
}

void 
mesh_delete(struct mesh_area* mesh)
{
  if(!mesh)
    return;
  /* free all query states */
  while(mesh->all.count)
    mesh_delete_helper(mesh->all.root);
  timehist_delete(mesh->histogram);
  sldns_buffer_free(mesh->qbuf_bak);
  free(mesh);
}

void
mesh_delete_all(struct mesh_area* mesh)
{
  /* free all query states */
  while(mesh->all.count)
    mesh_delete_helper(mesh->all.root);
  mesh->stats_dropped += mesh->num_reply_addrs;
  /* clear mesh area references */
  rbtree_init(&mesh->run, &mesh_state_compare);
  rbtree_init(&mesh->all, &mesh_state_compare);
  mesh->num_reply_addrs = 0;
  mesh->num_reply_states = 0;
  mesh->num_detached_states = 0;
  mesh->num_forever_states = 0;
  mesh->forever_first = NULL;
  mesh->forever_last = NULL;
  mesh->jostle_first = NULL;
  mesh->jostle_last = NULL;
}

int mesh_make_new_space(struct mesh_area* mesh, sldns_buffer* qbuf)
{
  struct mesh_state* m = mesh->jostle_first;
  /* free space is available */
  if(mesh->num_reply_states < mesh->max_reply_states)
    return 1;
  /* try to kick out a jostle-list item */
  if(m && m->reply_list && m->list_select == mesh_jostle_list) {
    /* how old is it? */
    struct timeval age;
    timeval_subtract(&age, mesh->env->now_tv, 
      &m->reply_list->start_time);
    if(timeval_smaller(&mesh->jostle_max, &age)) {
      /* its a goner */
      log_nametypeclass(VERB_ALGO, "query jostled out to "
        "make space for a new one",
        m->s.qinfo.qname, m->s.qinfo.qtype,
        m->s.qinfo.qclass);
      /* backup the query */
      if(qbuf) sldns_buffer_copy(mesh->qbuf_bak, qbuf);
      /* notify supers */
      if(m->super_set.count > 0) {
        verbose(VERB_ALGO, "notify supers of failure");
        m->s.return_msg = NULL;
        m->s.return_rcode = LDNS_RCODE_SERVFAIL;
        mesh_walk_supers(mesh, m);
      }
      mesh->stats_jostled ++;
      mesh_state_delete(&m->s);
      /* restore the query - note that the qinfo ptr to
       * the querybuffer is then correct again. */
      if(qbuf) sldns_buffer_copy(qbuf, mesh->qbuf_bak);
      return 1;
    }
  }
  /* no space for new item */
  return 0;
}

struct dns_msg*
mesh_serve_expired_lookup(struct module_qstate* qstate,
  struct query_info* lookup_qinfo)
{
  hashvalue_type h;
  struct lruhash_entry* e;
  struct dns_msg* msg;
  struct reply_info* data;
  struct msgreply_entry* key;
  time_t timenow = *qstate->env->now;
  int must_validate = (!(qstate->query_flags&BIT_CD)
    || qstate->env->cfg->ignore_cd) && qstate->env->need_to_validate;
  /* Lookup cache */
  h = query_info_hash(lookup_qinfo, qstate->query_flags);
  e = slabhash_lookup(qstate->env->msg_cache, h, lookup_qinfo, 0);
  if(!e) return NULL;

  key = (struct msgreply_entry*)e->key;
  data = (struct reply_info*)e->data;
  msg = tomsg(qstate->env, &key->key, data, qstate->region, timenow,
    qstate->env->cfg->serve_expired, qstate->env->scratch);
  if(!msg)
    goto bail_out;

  /* Check CNAME chain (if any)
   * This is part of tomsg above; no need to check now. */

  /* Check security status of the cached answer.
   * tomsg above has a subset of these checks, so we are leaving
   * these as is.
   * In case of bogus or revalidation we don't care to reply here. */
  if(must_validate && (msg->rep->security == sec_status_bogus ||
    msg->rep->security == sec_status_secure_sentinel_fail)) {
    verbose(VERB_ALGO, "Serve expired: bogus answer found in cache");
    goto bail_out;
  } else if(msg->rep->security == sec_status_unchecked && must_validate) {
    verbose(VERB_ALGO, "Serve expired: unchecked entry needs "
      "validation");
    goto bail_out; /* need to validate cache entry first */
  } else if(msg->rep->security == sec_status_secure &&
    !reply_all_rrsets_secure(msg->rep) && must_validate) {
      verbose(VERB_ALGO, "Serve expired: secure entry"
        " changed status");
      goto bail_out; /* rrset changed, re-verify */
  }

  lock_rw_unlock(&e->lock);
  return msg;

bail_out:
  lock_rw_unlock(&e->lock);
  return NULL;
}


/** Init the serve expired data structure */
static int
mesh_serve_expired_init(struct mesh_state* mstate, int timeout)
{
  struct timeval t;

  /* Create serve_expired_data if not there yet */
  if(!mstate->s.serve_expired_data) {
    mstate->s.serve_expired_data = (struct serve_expired_data*)
      regional_alloc_zero(
        mstate->s.region, sizeof(struct serve_expired_data));
    if(!mstate->s.serve_expired_data)
      return 0;
  }

  /* Don't overwrite the function if already set */
  mstate->s.serve_expired_data->get_cached_answer =
    mstate->s.serve_expired_data->get_cached_answer?
    mstate->s.serve_expired_data->get_cached_answer:
    &mesh_serve_expired_lookup;

  /* In case this timer already popped, start it again */
  if(!mstate->s.serve_expired_data->timer) {
    mstate->s.serve_expired_data->timer = comm_timer_create(
      mstate->s.env->worker_base, mesh_serve_expired_callback, mstate);
    if(!mstate->s.serve_expired_data->timer)
      return 0;
#ifndef S_SPLINT_S
    t.tv_sec = timeout/1000;
    t.tv_usec = (timeout%1000)*1000;
#endif
    comm_timer_set(mstate->s.serve_expired_data->timer, &t);
  }
  return 1;
}

void mesh_new_client(struct mesh_area* mesh, struct query_info* qinfo,
  struct respip_client_info* cinfo, uint16_t qflags,
  struct edns_data* edns, struct comm_reply* rep, uint16_t qid,
  int rpz_passthru)
{
  struct mesh_state* s = NULL;
  int unique = unique_mesh_state(edns->opt_list_in, mesh->env);
  int was_detached = 0;
  int was_noreply = 0;
  int added = 0;
  int timeout = mesh->env->cfg->serve_expired?
    mesh->env->cfg->serve_expired_client_timeout:0;
  struct sldns_buffer* r_buffer = rep->c->buffer;
  if(rep->c->tcp_req_info) {
    r_buffer = rep->c->tcp_req_info->spool_buffer;
  }
  if(!unique)
    s = mesh_area_find(mesh, cinfo, qinfo, qflags&(BIT_RD|BIT_CD), 0, 0);
  /* does this create a new reply state? */
  if(!s || s->list_select == mesh_no_list) {
    if(!mesh_make_new_space(mesh, rep->c->buffer)) {
      verbose(VERB_ALGO, "Too many queries. dropping "
        "incoming query.");
      comm_point_drop_reply(rep);
      mesh->stats_dropped++;
      return;
    }
    /* for this new reply state, the reply address is free,
     * so the limit of reply addresses does not stop reply states*/
  } else {
    /* protect our memory usage from storing reply addresses */
    if(mesh->num_reply_addrs > mesh->max_reply_states*16) {
      verbose(VERB_ALGO, "Too many requests queued. "
        "dropping incoming query.");
      comm_point_drop_reply(rep);
      mesh->stats_dropped++;
      return;
    }
  }
  /* see if it already exists, if not, create one */
  if(!s) {
#ifdef UNBOUND_DEBUG
    struct rbnode_type* n;
#endif
    s = mesh_state_create(mesh->env, qinfo, cinfo,
      qflags&(BIT_RD|BIT_CD), 0, 0);
    if(!s) {
      log_err("mesh_state_create: out of memory; SERVFAIL");
      if(!inplace_cb_reply_servfail_call(mesh->env, qinfo, NULL, NULL,
        LDNS_RCODE_SERVFAIL, edns, rep, mesh->env->scratch, mesh->env->now_tv))
          edns->opt_list_inplace_cb_out = NULL;
      error_encode(r_buffer, LDNS_RCODE_SERVFAIL,
        qinfo, qid, qflags, edns);
      comm_point_send_reply(rep);
      return;
    }
    if(unique)
      mesh_state_make_unique(s);
    s->s.rpz_passthru = rpz_passthru;
    /* copy the edns options we got from the front */
    if(edns->opt_list_in) {
      s->s.edns_opts_front_in = edns_opt_copy_region(edns->opt_list_in,
        s->s.region);
      if(!s->s.edns_opts_front_in) {
        log_err("mesh_state_create: out of memory; SERVFAIL");
        if(!inplace_cb_reply_servfail_call(mesh->env, qinfo, NULL,
          NULL, LDNS_RCODE_SERVFAIL, edns, rep, mesh->env->scratch, mesh->env->now_tv))
            edns->opt_list_inplace_cb_out = NULL;
        error_encode(r_buffer, LDNS_RCODE_SERVFAIL,
          qinfo, qid, qflags, edns);
        comm_point_send_reply(rep);
        return;
      }
    }

#ifdef UNBOUND_DEBUG
    n =
#else
    (void)
#endif
    rbtree_insert(&mesh->all, &s->node);
    log_assert(n != NULL);
    /* set detached (it is now) */
    mesh->num_detached_states++;
    added = 1;
  }
  if(!s->reply_list && !s->cb_list) {
    was_noreply = 1;
    if(s->super_set.count == 0) {
      was_detached = 1;
    }
  }
  /* add reply to s */
  if(!mesh_state_add_reply(s, edns, rep, qid, qflags, qinfo)) {
    log_err("mesh_new_client: out of memory; SERVFAIL");
    goto servfail_mem;
  }
  if(rep->c->tcp_req_info) {
    if(!tcp_req_info_add_meshstate(rep->c->tcp_req_info, mesh, s)) {
      log_err("mesh_new_client: out of memory add tcpreqinfo");
      goto servfail_mem;
    }
  }
  if(rep->c->use_h2) {
    http2_stream_add_meshstate(rep->c->h2_stream, mesh, s);
  }
  /* add serve expired timer if required and not already there */
  if(timeout && !mesh_serve_expired_init(s, timeout)) {
    log_err("mesh_new_client: out of memory initializing serve expired");
    goto servfail_mem;
  }
  /* update statistics */
  if(was_detached) {
    log_assert(mesh->num_detached_states > 0);
    mesh->num_detached_states--;
  }
  if(was_noreply) {
    mesh->num_reply_states ++;
  }
  mesh->num_reply_addrs++;
  if(s->list_select == mesh_no_list) {
    /* move to either the forever or the jostle_list */
    if(mesh->num_forever_states < mesh->max_forever_states) {
      mesh->num_forever_states ++;
      mesh_list_insert(s, &mesh->forever_first, 
        &mesh->forever_last);
      s->list_select = mesh_forever_list;
    } else {
      mesh_list_insert(s, &mesh->jostle_first, 
        &mesh->jostle_last);
      s->list_select = mesh_jostle_list;
    }
  }
  if(added)
    mesh_run(mesh, s, module_event_new, NULL);
  return;

servfail_mem:
  if(!inplace_cb_reply_servfail_call(mesh->env, qinfo, &s->s,
    NULL, LDNS_RCODE_SERVFAIL, edns, rep, mesh->env->scratch, mesh->env->now_tv))
      edns->opt_list_inplace_cb_out = NULL;
  error_encode(r_buffer, LDNS_RCODE_SERVFAIL,
    qinfo, qid, qflags, edns);
  comm_point_send_reply(rep);
  if(added)
    mesh_state_delete(&s->s);
  return;
}

int 
mesh_new_callback(struct mesh_area* mesh, struct query_info* qinfo,
  uint16_t qflags, struct edns_data* edns, sldns_buffer* buf, 
  uint16_t qid, mesh_cb_func_type cb, void* cb_arg, int rpz_passthru)
{
  struct mesh_state* s = NULL;
  int unique = unique_mesh_state(edns->opt_list_in, mesh->env);
  int timeout = mesh->env->cfg->serve_expired?
    mesh->env->cfg->serve_expired_client_timeout:0;
  int was_detached = 0;
  int was_noreply = 0;
  int added = 0;
  if(!unique)
    s = mesh_area_find(mesh, NULL, qinfo, qflags&(BIT_RD|BIT_CD), 0, 0);

  /* there are no limits on the number of callbacks */

  /* see if it already exists, if not, create one */
  if(!s) {
#ifdef UNBOUND_DEBUG
    struct rbnode_type* n;
#endif
    s = mesh_state_create(mesh->env, qinfo, NULL,
      qflags&(BIT_RD|BIT_CD), 0, 0);
    if(!s) {
      return 0;
    }
    if(unique)
      mesh_state_make_unique(s);
    s->s.rpz_passthru = rpz_passthru;
    if(edns->opt_list_in) {
      s->s.edns_opts_front_in = edns_opt_copy_region(edns->opt_list_in,
        s->s.region);
      if(!s->s.edns_opts_front_in) {
        return 0;
      }
    }
#ifdef UNBOUND_DEBUG
    n =
#else
    (void)
#endif
    rbtree_insert(&mesh->all, &s->node);
    log_assert(n != NULL);
    /* set detached (it is now) */
    mesh->num_detached_states++;
    added = 1;
  }
  if(!s->reply_list && !s->cb_list) {
    was_noreply = 1;
    if(s->super_set.count == 0) {
      was_detached = 1;
    }
  }
  /* add reply to s */
  if(!mesh_state_add_cb(s, edns, buf, cb, cb_arg, qid, qflags)) {
    if(added)
      mesh_state_delete(&s->s);
    return 0;
  }
  /* add serve expired timer if not already there */
  if(timeout && !mesh_serve_expired_init(s, timeout)) {
    return 0;
  }
  /* update statistics */
  if(was_detached) {
    log_assert(mesh->num_detached_states > 0);
    mesh->num_detached_states--;
  }
  if(was_noreply) {
    mesh->num_reply_states ++;
  }
  mesh->num_reply_addrs++;
  if(added)
    mesh_run(mesh, s, module_event_new, NULL);
  return 1;
}

/* Internal backend routine of mesh_new_prefetch().  It takes one additional
 * parameter, 'run', which controls whether to run the prefetch state
 * immediately.  When this function is called internally 'run' could be
 * 0 (false), in which case the new state is only made runnable so it
 * will not be run recursively on top of the current state. */
static void mesh_schedule_prefetch(struct mesh_area* mesh,
  struct query_info* qinfo, uint16_t qflags, time_t leeway, int run,
  int rpz_passthru)
{
  struct mesh_state* s = mesh_area_find(mesh, NULL, qinfo,
    qflags&(BIT_RD|BIT_CD), 0, 0);
#ifdef UNBOUND_DEBUG
  struct rbnode_type* n;
#endif
  /* already exists, and for a different purpose perhaps.
   * if mesh_no_list, keep it that way. */
  if(s) {
    /* make it ignore the cache from now on */
    if(!s->s.blacklist)
      sock_list_insert(&s->s.blacklist, NULL, 0, s->s.region);
    if(s->s.prefetch_leeway < leeway)
      s->s.prefetch_leeway = leeway;
    return;
  }
  if(!mesh_make_new_space(mesh, NULL)) {
    verbose(VERB_ALGO, "Too many queries. dropped prefetch.");
    mesh->stats_dropped ++;
    return;
  }

  s = mesh_state_create(mesh->env, qinfo, NULL,
    qflags&(BIT_RD|BIT_CD), 0, 0);
  if(!s) {
    log_err("prefetch mesh_state_create: out of memory");
    return;
  }
#ifdef UNBOUND_DEBUG
  n =
#else
  (void)
#endif
  rbtree_insert(&mesh->all, &s->node);
  log_assert(n != NULL);
  /* set detached (it is now) */
  mesh->num_detached_states++;
  /* make it ignore the cache */
  sock_list_insert(&s->s.blacklist, NULL, 0, s->s.region);
  s->s.prefetch_leeway = leeway;

  if(s->list_select == mesh_no_list) {
    /* move to either the forever or the jostle_list */
    if(mesh->num_forever_states < mesh->max_forever_states) {
      mesh->num_forever_states ++;
      mesh_list_insert(s, &mesh->forever_first,
        &mesh->forever_last);
      s->list_select = mesh_forever_list;
    } else {
      mesh_list_insert(s, &mesh->jostle_first,
        &mesh->jostle_last);
      s->list_select = mesh_jostle_list;
    }
  }
  s->s.rpz_passthru = rpz_passthru;

  if(!run) {
#ifdef UNBOUND_DEBUG
    n =
#else
    (void)
#endif
    rbtree_insert(&mesh->run, &s->run_node);
    log_assert(n != NULL);
    return;
  }

  mesh_run(mesh, s, module_event_new, NULL);
}

#ifdef CLIENT_SUBNET
/* Same logic as mesh_schedule_prefetch but tailored to the subnet module logic
 * like passing along the comm_reply info. This will be faked into an EDNS
 * option for processing by the subnet module if the client has not already
 * attached its own ECS data. */
static void mesh_schedule_prefetch_subnet(struct mesh_area* mesh,
  struct query_info* qinfo, uint16_t qflags, time_t leeway, int run,
  int rpz_passthru, struct comm_reply* rep, struct edns_option* edns_list)
{
  struct mesh_state* s = NULL;
  struct edns_option* opt = NULL;
#ifdef UNBOUND_DEBUG
  struct rbnode_type* n;
#endif
  if(!mesh_make_new_space(mesh, NULL)) {
    verbose(VERB_ALGO, "Too many queries. dropped prefetch.");
    mesh->stats_dropped ++;
    return;
  }

  s = mesh_state_create(mesh->env, qinfo, NULL,
    qflags&(BIT_RD|BIT_CD), 0, 0);
  if(!s) {
    log_err("prefetch_subnet mesh_state_create: out of memory");
    return;
  }
  mesh_state_make_unique(s);

  opt = edns_opt_list_find(edns_list, mesh->env->cfg->client_subnet_opcode);
  if(opt) {
    /* Use the client's ECS data */
    if(!edns_opt_list_append(&s->s.edns_opts_front_in, opt->opt_code,
      opt->opt_len, opt->opt_data, s->s.region)) {
      log_err("prefetch_subnet edns_opt_list_append: out of memory");
      return;
    }
  } else {
    /* Store the client's address. Later in the subnet module,
     * it is decided whether to include an ECS option or not.
     */
    s->s.client_addr =  rep->client_addr;
  }
#ifdef UNBOUND_DEBUG
  n =
#else
  (void)
#endif
  rbtree_insert(&mesh->all, &s->node);
  log_assert(n != NULL);
  /* set detached (it is now) */
  mesh->num_detached_states++;
  /* make it ignore the cache */
  sock_list_insert(&s->s.blacklist, NULL, 0, s->s.region);
  s->s.prefetch_leeway = leeway;

  if(s->list_select == mesh_no_list) {
    /* move to either the forever or the jostle_list */
    if(mesh->num_forever_states < mesh->max_forever_states) {
      mesh->num_forever_states ++;
      mesh_list_insert(s, &mesh->forever_first,
        &mesh->forever_last);
      s->list_select = mesh_forever_list;
    } else {
      mesh_list_insert(s, &mesh->jostle_first,
        &mesh->jostle_last);
      s->list_select = mesh_jostle_list;
    }
  }
  s->s.rpz_passthru = rpz_passthru;

  if(!run) {
#ifdef UNBOUND_DEBUG
    n =
#else
    (void)
#endif
    rbtree_insert(&mesh->run, &s->run_node);
    log_assert(n != NULL);
    return;
  }

  mesh_run(mesh, s, module_event_new, NULL);
}
#endif /* CLIENT_SUBNET */

void mesh_new_prefetch(struct mesh_area* mesh, struct query_info* qinfo,
  uint16_t qflags, time_t leeway, int rpz_passthru,
  struct comm_reply* rep, struct edns_option* opt_list)
{
  (void)opt_list;
  (void)rep;
#ifdef CLIENT_SUBNET
  if(rep)
    mesh_schedule_prefetch_subnet(mesh, qinfo, qflags, leeway, 1,
      rpz_passthru, rep, opt_list);
  else
#endif
    mesh_schedule_prefetch(mesh, qinfo, qflags, leeway, 1,
      rpz_passthru);
}

void mesh_report_reply(struct mesh_area* mesh, struct outbound_entry* e,
        struct comm_reply* reply, int what)
{
  enum module_ev event = module_event_reply;
  e->qstate->reply = reply;
  if(what != NETEVENT_NOERROR) {
    event = module_event_noreply;
    if(what == NETEVENT_CAPSFAIL)
      event = module_event_capsfail;
  }
  mesh_run(mesh, e->qstate->mesh_info, event, e);
}

struct mesh_state*
mesh_state_create(struct module_env* env, struct query_info* qinfo,
  struct respip_client_info* cinfo, uint16_t qflags, int prime,
  int valrec)
{
  struct regional* region = alloc_reg_obtain(env->alloc);
  struct mesh_state* mstate;
  int i;
  if(!region)
    return NULL;
  mstate = (struct mesh_state*)regional_alloc(region, 
    sizeof(struct mesh_state));
  if(!mstate) {
    alloc_reg_release(env->alloc, region);
    return NULL;
  }
  memset(mstate, 0, sizeof(*mstate));
  mstate->node = *RBTREE_NULL;
  mstate->run_node = *RBTREE_NULL;
  mstate->node.key = mstate;
  mstate->run_node.key = mstate;
  mstate->reply_list = NULL;
  mstate->list_select = mesh_no_list;
  mstate->replies_sent = 0;
  rbtree_init(&mstate->super_set, &mesh_state_ref_compare);
  rbtree_init(&mstate->sub_set, &mesh_state_ref_compare);
  mstate->num_activated = 0;
  mstate->unique = NULL;
  /* init module qstate */
  mstate->s.qinfo.qtype = qinfo->qtype;
  mstate->s.qinfo.qclass = qinfo->qclass;
  mstate->s.qinfo.local_alias = NULL;
  mstate->s.qinfo.qname_len = qinfo->qname_len;
  mstate->s.qinfo.qname = regional_alloc_init(region, qinfo->qname,
    qinfo->qname_len);
  if(!mstate->s.qinfo.qname) {
    alloc_reg_release(env->alloc, region);
    return NULL;
  }
  if(cinfo) {
    mstate->s.client_info = regional_alloc_init(region, cinfo,
      sizeof(*cinfo));
    if(!mstate->s.client_info) {
      alloc_reg_release(env->alloc, region);
      return NULL;
    }
  }
  /* remove all weird bits from qflags */
  mstate->s.query_flags = (qflags & (BIT_RD|BIT_CD));
  mstate->s.is_priming = prime;
  mstate->s.is_valrec = valrec;
  mstate->s.reply = NULL;
  mstate->s.region = region;
  mstate->s.curmod = 0;
  mstate->s.return_msg = 0;
  mstate->s.return_rcode = LDNS_RCODE_NOERROR;
  mstate->s.env = env;
  mstate->s.mesh_info = mstate;
  mstate->s.prefetch_leeway = 0;
  mstate->s.serve_expired_data = NULL;
  mstate->s.no_cache_lookup = 0;
  mstate->s.no_cache_store = 0;
  mstate->s.need_refetch = 0;
  mstate->s.was_ratelimited = 0;
  mstate->s.qstarttime = *env->now;

  /* init modules */
  for(i=0; i<env->mesh->mods.num; i++) {
    mstate->s.minfo[i] = NULL;
    mstate->s.ext_state[i] = module_state_initial;
  }
  /* init edns option lists */
  mstate->s.edns_opts_front_in = NULL;
  mstate->s.edns_opts_back_out = NULL;
  mstate->s.edns_opts_back_in = NULL;
  mstate->s.edns_opts_front_out = NULL;

  return mstate;
}

int
mesh_state_is_unique(struct mesh_state* mstate)
{
  return mstate->unique != NULL;
}

void
mesh_state_make_unique(struct mesh_state* mstate)
{
  mstate->unique = mstate;
}

void 
mesh_state_cleanup(struct mesh_state* mstate)
{
  struct mesh_area* mesh;
  int i;
  if(!mstate)
    return;
  mesh = mstate->s.env->mesh;
  /* Stop and delete the serve expired timer */
  if(mstate->s.serve_expired_data && mstate->s.serve_expired_data->timer) {
    comm_timer_delete(mstate->s.serve_expired_data->timer);
    mstate->s.serve_expired_data->timer = NULL;
  }
  /* drop unsent replies */
  if(!mstate->replies_sent) {
    struct mesh_reply* rep = mstate->reply_list;
    struct mesh_cb* cb;
    /* in tcp_req_info, the mstates linked are removed, but
     * the reply_list is now NULL, so the remove-from-empty-list
     * takes no time and also it does not do the mesh accounting */
    mstate->reply_list = NULL;
    for(; rep; rep=rep->next) {
      comm_point_drop_reply(&rep->query_reply);
      log_assert(mesh->num_reply_addrs > 0);
      mesh->num_reply_addrs--;
    }
    while((cb = mstate->cb_list)!=NULL) {
      mstate->cb_list = cb->next;
      fptr_ok(fptr_whitelist_mesh_cb(cb->cb));
      (*cb->cb)(cb->cb_arg, LDNS_RCODE_SERVFAIL, NULL,
        sec_status_unchecked, NULL, 0);
      log_assert(mesh->num_reply_addrs > 0);
      mesh->num_reply_addrs--;
    }
  }

  /* de-init modules */
  for(i=0; i<mesh->mods.num; i++) {
    fptr_ok(fptr_whitelist_mod_clear(mesh->mods.mod[i]->clear));
    (*mesh->mods.mod[i]->clear)(&mstate->s, i);
    mstate->s.minfo[i] = NULL;
    mstate->s.ext_state[i] = module_finished;
  }
  alloc_reg_release(mstate->s.env->alloc, mstate->s.region);
}

void 
mesh_state_delete(struct module_qstate* qstate)
{
  struct mesh_area* mesh;
  struct mesh_state_ref* super, ref;
  struct mesh_state* mstate;
  if(!qstate)
    return;
  mstate = qstate->mesh_info;
  mesh = mstate->s.env->mesh;
  mesh_detach_subs(&mstate->s);
  if(mstate->list_select == mesh_forever_list) {
    mesh->num_forever_states --;
    mesh_list_remove(mstate, &mesh->forever_first, 
      &mesh->forever_last);
  } else if(mstate->list_select == mesh_jostle_list) {
    mesh_list_remove(mstate, &mesh->jostle_first, 
      &mesh->jostle_last);
  }
  if(!mstate->reply_list && !mstate->cb_list
    && mstate->super_set.count == 0) {
    log_assert(mesh->num_detached_states > 0);
    mesh->num_detached_states--;
  }
  if(mstate->reply_list || mstate->cb_list) {
    log_assert(mesh->num_reply_states > 0);
    mesh->num_reply_states--;
  }
  ref.node.key = &ref;
  ref.s = mstate;
  RBTREE_FOR(super, struct mesh_state_ref*, &mstate->super_set) {
    (void)rbtree_delete(&super->s->sub_set, &ref);
  }
  (void)rbtree_delete(&mesh->run, mstate);
  (void)rbtree_delete(&mesh->all, mstate);
  mesh_state_cleanup(mstate);
}

/** helper recursive rbtree find routine */
static int
find_in_subsub(struct mesh_state* m, struct mesh_state* tofind, size_t *c)
{
  struct mesh_state_ref* r;
  if((*c)++ > MESH_MAX_SUBSUB)
    return 1;
  RBTREE_FOR(r, struct mesh_state_ref*, &m->sub_set) {
    if(r->s == tofind || find_in_subsub(r->s, tofind, c))
      return 1;
  }
  return 0;
}

/** find cycle for already looked up mesh_state */
static int
mesh_detect_cycle_found(struct module_qstate* qstate, struct mesh_state* dep_m)
{
  struct mesh_state* cyc_m = qstate->mesh_info;
  size_t counter = 0;
  if(!dep_m)
    return 0;
  if(dep_m == cyc_m || find_in_subsub(dep_m, cyc_m, &counter)) {
    if(counter > MESH_MAX_SUBSUB)
      return 2;
    return 1;
  }
  return 0;
}

void mesh_detach_subs(struct module_qstate* qstate)
{
  struct mesh_area* mesh = qstate->env->mesh;
  struct mesh_state_ref* ref, lookup;
#ifdef UNBOUND_DEBUG
  struct rbnode_type* n;
#endif
  lookup.node.key = &lookup;
  lookup.s = qstate->mesh_info;
  RBTREE_FOR(ref, struct mesh_state_ref*, &qstate->mesh_info->sub_set) {
#ifdef UNBOUND_DEBUG
    n =
#else
    (void)
#endif
    rbtree_delete(&ref->s->super_set, &lookup);
    log_assert(n != NULL); /* must have been present */
    if(!ref->s->reply_list && !ref->s->cb_list
      && ref->s->super_set.count == 0) {
      mesh->num_detached_states++;
      log_assert(mesh->num_detached_states + 
        mesh->num_reply_states <= mesh->all.count);
    }
  }
  rbtree_init(&qstate->mesh_info->sub_set, &mesh_state_ref_compare);
}

int mesh_add_sub(struct module_qstate* qstate, struct query_info* qinfo,
        uint16_t qflags, int prime, int valrec, struct module_qstate** newq,
  struct mesh_state** sub)
{
  /* find it, if not, create it */
  struct mesh_area* mesh = qstate->env->mesh;
  *sub = mesh_area_find(mesh, NULL, qinfo, qflags,
    prime, valrec);
  if(mesh_detect_cycle_found(qstate, *sub)) {
    verbose(VERB_ALGO, "attach failed, cycle detected");
    return 0;
  }
  if(!*sub) {
#ifdef UNBOUND_DEBUG
    struct rbnode_type* n;
#endif
    /* create a new one */
    *sub = mesh_state_create(qstate->env, qinfo, NULL, qflags, prime,
      valrec);
    if(!*sub) {
      log_err("mesh_attach_sub: out of memory");
      return 0;
    }
#ifdef UNBOUND_DEBUG
    n =
#else
    (void)
#endif
    rbtree_insert(&mesh->all, &(*sub)->node);
    log_assert(n != NULL);
    /* set detached (it is now) */
    mesh->num_detached_states++;
    /* set new query state to run */
#ifdef UNBOUND_DEBUG
    n =
#else
    (void)
#endif
    rbtree_insert(&mesh->run, &(*sub)->run_node);
    log_assert(n != NULL);
    *newq = &(*sub)->s;
  } else
    *newq = NULL;
  return 1;
}

int mesh_attach_sub(struct module_qstate* qstate, struct query_info* qinfo,
        uint16_t qflags, int prime, int valrec, struct module_qstate** newq)
{
  struct mesh_area* mesh = qstate->env->mesh;
  struct mesh_state* sub = NULL;
  int was_detached;
  if(!mesh_add_sub(qstate, qinfo, qflags, prime, valrec, newq, &sub))
    return 0;
  was_detached = (sub->super_set.count == 0);
  if(!mesh_state_attachment(qstate->mesh_info, sub))
    return 0;
  /* if it was a duplicate  attachment, the count was not zero before */
  if(!sub->reply_list && !sub->cb_list && was_detached && 
    sub->super_set.count == 1) {
    /* it used to be detached, before this one got added */
    log_assert(mesh->num_detached_states > 0);
    mesh->num_detached_states--;
  }
  /* *newq will be run when inited after the current module stops */
  return 1;
}

int mesh_state_attachment(struct mesh_state* super, struct mesh_state* sub)
{
#ifdef UNBOUND_DEBUG
  struct rbnode_type* n;
#endif
  struct mesh_state_ref* subref; /* points to sub, inserted in super */
  struct mesh_state_ref* superref; /* points to super, inserted in sub */
  if( !(subref = regional_alloc(super->s.region,
    sizeof(struct mesh_state_ref))) ||
    !(superref = regional_alloc(sub->s.region,
    sizeof(struct mesh_state_ref))) ) {
    log_err("mesh_state_attachment: out of memory");
    return 0;
  }
  superref->node.key = superref;
  superref->s = super;
  subref->node.key = subref;
  subref->s = sub;
  if(!rbtree_insert(&sub->super_set, &superref->node)) {
    /* this should not happen, iterator and validator do not
     * attach subqueries that are identical. */
    /* already attached, we are done, nothing todo.
     * since superref and subref already allocated in region,
     * we cannot free them */
    return 1;
  }
#ifdef UNBOUND_DEBUG
  n =
#else
  (void)
#endif
  rbtree_insert(&super->sub_set, &subref->node);
  log_assert(n != NULL); /* we checked above if statement, the reverse
    administration should not fail now, unless they are out of sync */
  return 1;
}

/**
 * callback results to mesh cb entry
 * @param m: mesh state to send it for.
 * @param rcode: if not 0, error code.
 * @param rep: reply to send (or NULL if rcode is set).
 * @param r: callback entry
 * @param start_time: the time to pass to callback functions, it is 0 or
 *  a value from one of the packets if the mesh state had packets.
 */
static void
mesh_do_callback(struct mesh_state* m, int rcode, struct reply_info* rep,
  struct mesh_cb* r, struct timeval* start_time)
{
  int secure;
  char* reason = NULL;
  int was_ratelimited = m->s.was_ratelimited;
  /* bogus messages are not made into servfail, sec_status passed
   * to the callback function */
  if(rep && rep->security == sec_status_secure)
    secure = 1;
  else  secure = 0;
  if(!rep && rcode == LDNS_RCODE_NOERROR)
    rcode = LDNS_RCODE_SERVFAIL;
  if(!rcode && (rep->security == sec_status_bogus ||
    rep->security == sec_status_secure_sentinel_fail)) {
    if(!(reason = errinf_to_str_bogus(&m->s)))
      rcode = LDNS_RCODE_SERVFAIL;
  }
  /* send the reply */
  if(rcode) {
    if(rcode == LDNS_RCODE_SERVFAIL) {
      if(!inplace_cb_reply_servfail_call(m->s.env, &m->s.qinfo, &m->s,
        rep, rcode, &r->edns, NULL, m->s.region, start_time))
          r->edns.opt_list_inplace_cb_out = NULL;
    } else {
      if(!inplace_cb_reply_call(m->s.env, &m->s.qinfo, &m->s, rep, rcode,
        &r->edns, NULL, m->s.region, start_time))
          r->edns.opt_list_inplace_cb_out = NULL;
    }
    fptr_ok(fptr_whitelist_mesh_cb(r->cb));
    (*r->cb)(r->cb_arg, rcode, r->buf, sec_status_unchecked, NULL,
      was_ratelimited);
  } else {
    size_t udp_size = r->edns.udp_size;
    sldns_buffer_clear(r->buf);
    r->edns.edns_version = EDNS_ADVERTISED_VERSION;
    r->edns.udp_size = EDNS_ADVERTISED_SIZE;
    r->edns.ext_rcode = 0;
    r->edns.bits &= EDNS_DO;

    if(!inplace_cb_reply_call(m->s.env, &m->s.qinfo, &m->s, rep,
      LDNS_RCODE_NOERROR, &r->edns, NULL, m->s.region, start_time) ||
      !reply_info_answer_encode(&m->s.qinfo, rep, r->qid, 
      r->qflags, r->buf, 0, 1, 
      m->s.env->scratch, udp_size, &r->edns, 
      (int)(r->edns.bits & EDNS_DO), secure)) 
    {
      fptr_ok(fptr_whitelist_mesh_cb(r->cb));
      (*r->cb)(r->cb_arg, LDNS_RCODE_SERVFAIL, r->buf,
        sec_status_unchecked, NULL, 0);
    } else {
      fptr_ok(fptr_whitelist_mesh_cb(r->cb));
      (*r->cb)(r->cb_arg, LDNS_RCODE_NOERROR, r->buf,
        rep->security, reason, was_ratelimited);
    }
  }
  free(reason);
  log_assert(m->s.env->mesh->num_reply_addrs > 0);
  m->s.env->mesh->num_reply_addrs--;
}

static inline int
mesh_is_rpz_respip_tcponly_action(struct mesh_state const* m)
{
  struct respip_action_info const* respip_info = m->s.respip_action_info;
  return respip_info == NULL
      ? 0
      : (respip_info->rpz_used
      && !respip_info->rpz_disabled
      && respip_info->action == respip_truncate);
}

static inline int
mesh_is_udp(struct mesh_reply const* r) {
  return r->query_reply.c->type == comm_udp;
}

/**
 * Send reply to mesh reply entry
 * @param m: mesh state to send it for.
 * @param rcode: if not 0, error code.
 * @param rep: reply to send (or NULL if rcode is set).
 * @param r: reply entry
 * @param r_buffer: buffer to use for reply entry.
 * @param prev: previous reply, already has its answer encoded in buffer.
 * @param prev_buffer: buffer for previous reply.
 */
static void
mesh_send_reply(struct mesh_state* m, int rcode, struct reply_info* rep,
  struct mesh_reply* r, struct sldns_buffer* r_buffer,
  struct mesh_reply* prev, struct sldns_buffer* prev_buffer)
{
  struct timeval end_time;
  struct timeval duration;
  int secure;
  /* briefly set the replylist to null in case the
   * meshsendreply calls tcpreqinfo sendreply that
   * comm_point_drops because of size, and then the
   * null stops the mesh state remove and thus
   * reply_list modification and accounting */
  struct mesh_reply* rlist = m->reply_list;

  /* rpz: apply actions */
  rcode = mesh_is_udp(r) && mesh_is_rpz_respip_tcponly_action(m)
      ? (rcode|BIT_TC) : rcode;

  /* examine security status */
  if(m->s.env->need_to_validate && (!(r->qflags&BIT_CD) ||
    m->s.env->cfg->ignore_cd) && rep && 
    (rep->security <= sec_status_bogus ||
    rep->security == sec_status_secure_sentinel_fail)) {
    rcode = LDNS_RCODE_SERVFAIL;
    if(m->s.env->cfg->stat_extended)
      m->s.env->mesh->ans_bogus++;
  }
  if(rep && rep->security == sec_status_secure)
    secure = 1;
  else  secure = 0;
  if(!rep && rcode == LDNS_RCODE_NOERROR)
    rcode = LDNS_RCODE_SERVFAIL;
  if(r->query_reply.c->use_h2) {
    r->query_reply.c->h2_stream = r->h2_stream;
    /* Mesh reply won't exist for long anymore. Make it impossible
     * for HTTP/2 stream to refer to mesh state, in case
     * connection gets cleanup before HTTP/2 stream close. */
    r->h2_stream->mesh_state = NULL;
  }
  /* send the reply */
  /* We don't reuse the encoded answer if:
   * - either the previous or current response has a local alias.  We could
   *   compare the alias records and still reuse the previous answer if they
   *   are the same, but that would be complicated and error prone for the
   *   relatively minor case. So we err on the side of safety.
   * - there are registered callback functions for the given rcode, as these
   *   need to be called for each reply. */
  if(((rcode != LDNS_RCODE_SERVFAIL &&
      !m->s.env->inplace_cb_lists[inplace_cb_reply]) ||
    (rcode == LDNS_RCODE_SERVFAIL &&
      !m->s.env->inplace_cb_lists[inplace_cb_reply_servfail])) &&
    prev && prev_buffer && prev->qflags == r->qflags &&
    !prev->local_alias && !r->local_alias &&
    prev->edns.edns_present == r->edns.edns_present &&
    prev->edns.bits == r->edns.bits &&
    prev->edns.udp_size == r->edns.udp_size &&
    edns_opt_list_compare(prev->edns.opt_list_out, r->edns.opt_list_out) == 0 &&
    edns_opt_list_compare(prev->edns.opt_list_inplace_cb_out, r->edns.opt_list_inplace_cb_out) == 0
    ) {
    /* if the previous reply is identical to this one, fix ID */
    if(prev_buffer != r_buffer)
      sldns_buffer_copy(r_buffer, prev_buffer);
    sldns_buffer_write_at(r_buffer, 0, &r->qid, sizeof(uint16_t));
    sldns_buffer_write_at(r_buffer, 12, r->qname,
      m->s.qinfo.qname_len);
    m->reply_list = NULL;
    comm_point_send_reply(&r->query_reply);
    m->reply_list = rlist;
  } else if(rcode) {
    m->s.qinfo.qname = r->qname;
    m->s.qinfo.local_alias = r->local_alias;
    if(rcode == LDNS_RCODE_SERVFAIL) {
      if(!inplace_cb_reply_servfail_call(m->s.env, &m->s.qinfo, &m->s,
        rep, rcode, &r->edns, &r->query_reply, m->s.region, &r->start_time))
          r->edns.opt_list_inplace_cb_out = NULL;
    } else { 
      if(!inplace_cb_reply_call(m->s.env, &m->s.qinfo, &m->s, rep, rcode,
        &r->edns, &r->query_reply, m->s.region, &r->start_time))
          r->edns.opt_list_inplace_cb_out = NULL;
    }
    /* Send along EDE BOGUS EDNS0 option when answer is bogus */
    if(m->s.env->cfg->ede && rcode == LDNS_RCODE_SERVFAIL &&
      m->s.env->need_to_validate && (!(r->qflags&BIT_CD) ||
      m->s.env->cfg->ignore_cd) && rep &&
      (rep->security <= sec_status_bogus ||
      rep->security == sec_status_secure_sentinel_fail)) {
      char *reason = m->s.env->cfg->val_log_level >= 2
        ? errinf_to_str_bogus(&m->s) : NULL;

      /* During validation the EDE code can be received via two
       * code paths. One code path fills the reply_info EDE, and
       * the other fills it in the errinf_strlist. These paths
       * intersect at some points, but where is opaque due to
       * the complexity of the validator. At the time of writing
       * we make the choice to prefer the EDE from errinf_strlist
       * but a compelling reason to do otherwise is just as valid
       */
      sldns_ede_code reason_bogus = errinf_to_reason_bogus(&m->s);
      if ((reason_bogus == LDNS_EDE_DNSSEC_BOGUS &&
        rep->reason_bogus != LDNS_EDE_NONE) ||
        reason_bogus == LDNS_EDE_NONE) {
          reason_bogus = rep->reason_bogus;
      }

      if(reason_bogus != LDNS_EDE_NONE) {
        edns_opt_list_append_ede(&r->edns.opt_list_out,
          m->s.region, reason_bogus, reason);
      }
      free(reason);
    }
    error_encode(r_buffer, rcode, &m->s.qinfo, r->qid,
      r->qflags, &r->edns);
    m->reply_list = NULL;
    comm_point_send_reply(&r->query_reply);
    m->reply_list = rlist;
  } else {
    size_t udp_size = r->edns.udp_size;
    r->edns.edns_version = EDNS_ADVERTISED_VERSION;
    r->edns.udp_size = EDNS_ADVERTISED_SIZE;
    r->edns.ext_rcode = 0;
    r->edns.bits &= EDNS_DO;
    m->s.qinfo.qname = r->qname;
    m->s.qinfo.local_alias = r->local_alias;
    if(!inplace_cb_reply_call(m->s.env, &m->s.qinfo, &m->s, rep,
      LDNS_RCODE_NOERROR, &r->edns, &r->query_reply, m->s.region, &r->start_time) ||
      !reply_info_answer_encode(&m->s.qinfo, rep, r->qid, 
      r->qflags, r_buffer, 0, 1, m->s.env->scratch,
      udp_size, &r->edns, (int)(r->edns.bits & EDNS_DO),
      secure)) 
    {
      if(!inplace_cb_reply_servfail_call(m->s.env, &m->s.qinfo, &m->s,
      rep, LDNS_RCODE_SERVFAIL, &r->edns, &r->query_reply, m->s.region, &r->start_time))
        r->edns.opt_list_inplace_cb_out = NULL;
      /* internal server error (probably malloc failure) so no
       * EDE (RFC8914) needed */
      error_encode(r_buffer, LDNS_RCODE_SERVFAIL,
        &m->s.qinfo, r->qid, r->qflags, &r->edns);
    }
    m->reply_list = NULL;
    comm_point_send_reply(&r->query_reply);
    m->reply_list = rlist;
  }
  /* account */
  log_assert(m->s.env->mesh->num_reply_addrs > 0);
  m->s.env->mesh->num_reply_addrs--;
  end_time = *m->s.env->now_tv;
  timeval_subtract(&duration, &end_time, &r->start_time);
  verbose(VERB_ALGO, "query took " ARG_LL "d.%6.6d sec",
    (long long)duration.tv_sec, (int)duration.tv_usec);
  m->s.env->mesh->replies_sent++;
  timeval_add(&m->s.env->mesh->replies_sum_wait, &duration);
  timehist_insert(m->s.env->mesh->histogram, &duration);
  if(m->s.env->cfg->stat_extended) {
    uint16_t rc = FLAGS_GET_RCODE(sldns_buffer_read_u16_at(
      r_buffer, 2));
    if(secure) m->s.env->mesh->ans_secure++;
    m->s.env->mesh->ans_rcode[ rc ] ++;
    if(rc == 0 && LDNS_ANCOUNT(sldns_buffer_begin(r_buffer)) == 0)
      m->s.env->mesh->ans_nodata++;
  }
  /* Log reply sent */
  if(m->s.env->cfg->log_replies) {
    log_reply_info(NO_VERBOSE, &m->s.qinfo,
      &r->query_reply.client_addr,
      r->query_reply.client_addrlen, duration, 0, r_buffer);
  }
}

void mesh_query_done(struct mesh_state* mstate)
{
  struct mesh_reply* r;
  struct mesh_reply* prev = NULL;
  struct sldns_buffer* prev_buffer = NULL;
  struct mesh_cb* c;
  struct reply_info* rep = (mstate->s.return_msg?
    mstate->s.return_msg->rep:NULL);
  struct timeval tv = {0, 0};
  /* No need for the serve expired timer anymore; we are going to reply. */
  if(mstate->s.serve_expired_data) {
    comm_timer_delete(mstate->s.serve_expired_data->timer);
    mstate->s.serve_expired_data->timer = NULL;
  }
  if(mstate->s.return_rcode == LDNS_RCODE_SERVFAIL ||
    (rep && FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_SERVFAIL)) {
    /* we are SERVFAILing; check for expired answer here */
    mesh_serve_expired_callback(mstate);
    if((mstate->reply_list || mstate->cb_list)
    && mstate->s.env->cfg->log_servfail
    && !mstate->s.env->cfg->val_log_squelch) {
      char* err = errinf_to_str_servfail(&mstate->s);
      if(err)
        log_err("%s", err);
      free(err);
    }
  }
  for(r = mstate->reply_list; r; r = r->next) {
    tv = r->start_time;

    /* if a response-ip address block has been stored the
     *  information should be logged for each client. */
    if(mstate->s.respip_action_info &&
      mstate->s.respip_action_info->addrinfo) {
      respip_inform_print(mstate->s.respip_action_info,
        r->qname, mstate->s.qinfo.qtype,
        mstate->s.qinfo.qclass, r->local_alias,
        &r->query_reply.client_addr,
        r->query_reply.client_addrlen);
      if(mstate->s.env->cfg->stat_extended &&
        mstate->s.respip_action_info->rpz_used) {
        if(mstate->s.respip_action_info->rpz_disabled)
          mstate->s.env->mesh->rpz_action[RPZ_DISABLED_ACTION]++;
        if(mstate->s.respip_action_info->rpz_cname_override)
          mstate->s.env->mesh->rpz_action[RPZ_CNAME_OVERRIDE_ACTION]++;
        else
          mstate->s.env->mesh->rpz_action[respip_action_to_rpz_action(
            mstate->s.respip_action_info->action)]++;
      }
    }

    /* if this query is determined to be dropped during the
     * mesh processing, this is the point to take that action. */
    if(mstate->s.is_drop) {
      /* briefly set the reply_list to NULL, so that the
       * tcp req info cleanup routine that calls the mesh
       * to deregister the meshstate for it is not done
       * because the list is NULL and also accounting is not
       * done there, but instead we do that here. */
      struct mesh_reply* reply_list = mstate->reply_list;
      mstate->reply_list = NULL;
      comm_point_drop_reply(&r->query_reply);
      mstate->reply_list = reply_list;
    } else {
      struct sldns_buffer* r_buffer = r->query_reply.c->buffer;
      if(r->query_reply.c->tcp_req_info) {
        r_buffer = r->query_reply.c->tcp_req_info->spool_buffer;
        prev_buffer = NULL;
      }
      mesh_send_reply(mstate, mstate->s.return_rcode, rep,
        r, r_buffer, prev, prev_buffer);
      if(r->query_reply.c->tcp_req_info) {
        tcp_req_info_remove_mesh_state(r->query_reply.c->tcp_req_info, mstate);
        r_buffer = NULL;
      }
      prev = r;
      prev_buffer = r_buffer;
    }
  }
  if(mstate->reply_list) {
    mstate->reply_list = NULL;
    if(!mstate->reply_list && !mstate->cb_list) {
      /* was a reply state, not anymore */
      log_assert(mstate->s.env->mesh->num_reply_states > 0);
      mstate->s.env->mesh->num_reply_states--;
    }
    if(!mstate->reply_list && !mstate->cb_list &&
      mstate->super_set.count == 0)
      mstate->s.env->mesh->num_detached_states++;
  }
  mstate->replies_sent = 1;
  while((c = mstate->cb_list) != NULL) {
    /* take this cb off the list; so that the list can be
     * changed, eg. by adds from the callback routine */
    if(!mstate->reply_list && mstate->cb_list && !c->next) {
      /* was a reply state, not anymore */
      log_assert(mstate->s.env->mesh->num_reply_states > 0);
      mstate->s.env->mesh->num_reply_states--;
    }
    mstate->cb_list = c->next;
    if(!mstate->reply_list && !mstate->cb_list &&
      mstate->super_set.count == 0)
      mstate->s.env->mesh->num_detached_states++;
    mesh_do_callback(mstate, mstate->s.return_rcode, rep, c, &tv);
  }
}

void mesh_walk_supers(struct mesh_area* mesh, struct mesh_state* mstate)
{
  struct mesh_state_ref* ref;
  RBTREE_FOR(ref, struct mesh_state_ref*, &mstate->super_set)
  {
    /* make super runnable */
    (void)rbtree_insert(&mesh->run, &ref->s->run_node);
    /* callback the function to inform super of result */
    fptr_ok(fptr_whitelist_mod_inform_super(
      mesh->mods.mod[ref->s->s.curmod]->inform_super));
    (*mesh->mods.mod[ref->s->s.curmod]->inform_super)(&mstate->s, 
      ref->s->s.curmod, &ref->s->s);
    /* copy state that is always relevant to super */
    copy_state_to_super(&mstate->s, ref->s->s.curmod, &ref->s->s);
  }
}

struct mesh_state* mesh_area_find(struct mesh_area* mesh,
  struct respip_client_info* cinfo, struct query_info* qinfo,
  uint16_t qflags, int prime, int valrec)
{
  struct mesh_state key;
  struct mesh_state* result;

  key.node.key = &key;
  key.s.is_priming = prime;
  key.s.is_valrec = valrec;
  key.s.qinfo = *qinfo;
  key.s.query_flags = qflags;
  /* We are searching for a similar mesh state when we DO want to
   * aggregate the state. Thus unique is set to NULL. (default when we
   * desire aggregation).*/
  key.unique = NULL;
  key.s.client_info = cinfo;
  
  result = (struct mesh_state*)rbtree_search(&mesh->all, &key);
  return result;
}

int mesh_state_add_cb(struct mesh_state* s, struct edns_data* edns,
        sldns_buffer* buf, mesh_cb_func_type cb, void* cb_arg,
  uint16_t qid, uint16_t qflags)
{
  struct mesh_cb* r = regional_alloc(s->s.region, 
    sizeof(struct mesh_cb));
  if(!r)
    return 0;
  r->buf = buf;
  log_assert(fptr_whitelist_mesh_cb(cb)); /* early failure ifmissing*/
  r->cb = cb;
  r->cb_arg = cb_arg;
  r->edns = *edns;
  if(edns->opt_list_in && !(r->edns.opt_list_in =
      edns_opt_copy_region(edns->opt_list_in, s->s.region)))
    return 0;
  if(edns->opt_list_out && !(r->edns.opt_list_out =
      edns_opt_copy_region(edns->opt_list_out, s->s.region)))
    return 0;
  if(edns->opt_list_inplace_cb_out && !(r->edns.opt_list_inplace_cb_out =
      edns_opt_copy_region(edns->opt_list_inplace_cb_out, s->s.region)))
    return 0;
  r->qid = qid;
  r->qflags = qflags;
  r->next = s->cb_list;
  s->cb_list = r;
  return 1;

}

int mesh_state_add_reply(struct mesh_state* s, struct edns_data* edns,
        struct comm_reply* rep, uint16_t qid, uint16_t qflags,
        const struct query_info* qinfo)
{
  struct mesh_reply* r = regional_alloc(s->s.region,
    sizeof(struct mesh_reply));
  if(!r)
    return 0;
  r->query_reply = *rep;
  r->edns = *edns;
  if(edns->opt_list_in && !(r->edns.opt_list_in =
      edns_opt_copy_region(edns->opt_list_in, s->s.region)))
    return 0;
  if(edns->opt_list_out && !(r->edns.opt_list_out =
      edns_opt_copy_region(edns->opt_list_out, s->s.region)))
    return 0;
  if(edns->opt_list_inplace_cb_out && !(r->edns.opt_list_inplace_cb_out =
      edns_opt_copy_region(edns->opt_list_inplace_cb_out, s->s.region)))
    return 0;
  r->qid = qid;
  r->qflags = qflags;
  r->start_time = *s->s.env->now_tv;
  r->next = s->reply_list;
  r->qname = regional_alloc_init(s->s.region, qinfo->qname,
    s->s.qinfo.qname_len);
  if(!r->qname)
    return 0;
  if(rep->c->use_h2)
    r->h2_stream = rep->c->h2_stream;

  /* Data related to local alias stored in 'qinfo' (if any) is ephemeral
   * and can be different for different original queries (even if the
   * replaced query name is the same).  So we need to make a deep copy
   * and store the copy for each reply info. */
  if(qinfo->local_alias) {
    struct packed_rrset_data* d;
    struct packed_rrset_data* dsrc;
    r->local_alias = regional_alloc_zero(s->s.region,
      sizeof(*qinfo->local_alias));
    if(!r->local_alias)
      return 0;
    r->local_alias->rrset = regional_alloc_init(s->s.region,
      qinfo->local_alias->rrset,
      sizeof(*qinfo->local_alias->rrset));
    if(!r->local_alias->rrset)
      return 0;
    dsrc = qinfo->local_alias->rrset->entry.data;

    /* In the current implementation, a local alias must be
     * a single CNAME RR (see worker_handle_request()). */
    log_assert(!qinfo->local_alias->next && dsrc->count == 1 &&
      qinfo->local_alias->rrset->rk.type ==
      htons(LDNS_RR_TYPE_CNAME));
    /* we should make a local copy for the owner name of
     * the RRset */
    r->local_alias->rrset->rk.dname_len =
      qinfo->local_alias->rrset->rk.dname_len;
    r->local_alias->rrset->rk.dname = regional_alloc_init(
      s->s.region, qinfo->local_alias->rrset->rk.dname,
      qinfo->local_alias->rrset->rk.dname_len);
    if(!r->local_alias->rrset->rk.dname)
      return 0;

    /* the rrset is not packed, like in the cache, but it is
     * individually allocated with an allocator from localzone. */
    d = regional_alloc_zero(s->s.region, sizeof(*d));
    if(!d)
      return 0;
    r->local_alias->rrset->entry.data = d;
    if(!rrset_insert_rr(s->s.region, d, dsrc->rr_data[0],
      dsrc->rr_len[0], dsrc->rr_ttl[0], "CNAME local alias"))
      return 0;
  } else
    r->local_alias = NULL;

  s->reply_list = r;
  return 1;
}

/* Extract the query info and flags from 'mstate' into '*qinfop' and '*qflags'.
 * Since this is only used for internal refetch of otherwise-expired answer,
 * we simply ignore the rare failure mode when memory allocation fails. */
static void
mesh_copy_qinfo(struct mesh_state* mstate, struct query_info** qinfop,
  uint16_t* qflags)
{
  struct regional* region = mstate->s.env->scratch;
  struct query_info* qinfo;

  qinfo = regional_alloc_init(region, &mstate->s.qinfo, sizeof(*qinfo));
  if(!qinfo)
    return;
  qinfo->qname = regional_alloc_init(region, qinfo->qname,
    qinfo->qname_len);
  if(!qinfo->qname)
    return;
  *qinfop = qinfo;
  *qflags = mstate->s.query_flags;
}

/**
 * Continue processing the mesh state at another module.
 * Handles module to modules transfer of control.
 * Handles module finished.
 * @param mesh: the mesh area.
 * @param mstate: currently active mesh state.
 *  Deleted if finished, calls _done and _supers to 
 *  send replies to clients and inform other mesh states.
 *  This in turn may create additional runnable mesh states.
 * @param s: state at which the current module exited.
 * @param ev: the event sent to the module.
 *  returned is the event to send to the next module.
 * @return true if continue processing at the new module.
 *  false if not continued processing is needed.
 */
static int
mesh_continue(struct mesh_area* mesh, struct mesh_state* mstate,
  enum module_ext_state s, enum module_ev* ev)
{
  mstate->num_activated++;
  if(mstate->num_activated > MESH_MAX_ACTIVATION) {
    /* module is looping. Stop it. */
    log_err("internal error: looping module (%s) stopped",
      mesh->mods.mod[mstate->s.curmod]->name);
    log_query_info(NO_VERBOSE, "pass error for qstate",
      &mstate->s.qinfo);
    s = module_error;
  }
  if(s == module_wait_module || s == module_restart_next) {
    /* start next module */
    mstate->s.curmod++;
    if(mesh->mods.num == mstate->s.curmod) {
      log_err("Cannot pass to next module; at last module");
      log_query_info(VERB_QUERY, "pass error for qstate",
        &mstate->s.qinfo);
      mstate->s.curmod--;
      return mesh_continue(mesh, mstate, module_error, ev);
    }
    if(s == module_restart_next) {
      int curmod = mstate->s.curmod;
      for(; mstate->s.curmod < mesh->mods.num; 
        mstate->s.curmod++) {
        fptr_ok(fptr_whitelist_mod_clear(
          mesh->mods.mod[mstate->s.curmod]->clear));
        (*mesh->mods.mod[mstate->s.curmod]->clear)
          (&mstate->s, mstate->s.curmod);
        mstate->s.minfo[mstate->s.curmod] = NULL;
      }
      mstate->s.curmod = curmod;
    }
    *ev = module_event_pass;
    return 1;
  }
  if(s == module_wait_subquery && mstate->sub_set.count == 0) {
    log_err("module cannot wait for subquery, subquery list empty");
    log_query_info(VERB_QUERY, "pass error for qstate",
      &mstate->s.qinfo);
    s = module_error;
  }
  if(s == module_error && mstate->s.return_rcode == LDNS_RCODE_NOERROR) {
    /* error is bad, handle pass back up below */
    mstate->s.return_rcode = LDNS_RCODE_SERVFAIL;
  }
  if(s == module_error) {
    mesh_query_done(mstate);
    mesh_walk_supers(mesh, mstate);
    mesh_state_delete(&mstate->s);
    return 0;
  }
  if(s == module_finished) {
    if(mstate->s.curmod == 0) {
      struct query_info* qinfo = NULL;
      uint16_t qflags;
      int rpz_p = 0;

      mesh_query_done(mstate);
      mesh_walk_supers(mesh, mstate);

      /* If the answer to the query needs to be refetched
       * from an external DNS server, we'll need to schedule
       * a prefetch after removing the current state, so
       * we need to make a copy of the query info here. */
      if(mstate->s.need_refetch) {
        mesh_copy_qinfo(mstate, &qinfo, &qflags);
        rpz_p = mstate->s.rpz_passthru;
      }

      mesh_state_delete(&mstate->s);
      if(qinfo) {
        mesh_schedule_prefetch(mesh, qinfo, qflags,
          0, 1, rpz_p);
      }
      return 0;
    }
    /* pass along the locus of control */
    mstate->s.curmod --;
    *ev = module_event_moddone;
    return 1;
  }
  return 0;
}

void mesh_run(struct mesh_area* mesh, struct mesh_state* mstate,
  enum module_ev ev, struct outbound_entry* e)
{
  enum module_ext_state s;
  verbose(VERB_ALGO, "mesh_run: start");
  while(mstate) {
    /* run the module */
    fptr_ok(fptr_whitelist_mod_operate(
      mesh->mods.mod[mstate->s.curmod]->operate));
    (*mesh->mods.mod[mstate->s.curmod]->operate)
      (&mstate->s, ev, mstate->s.curmod, e);

    /* examine results */
    mstate->s.reply = NULL;
    regional_free_all(mstate->s.env->scratch);
    s = mstate->s.ext_state[mstate->s.curmod];
    verbose(VERB_ALGO, "mesh_run: %s module exit state is %s", 
      mesh->mods.mod[mstate->s.curmod]->name, strextstate(s));
    e = NULL;
    if(mesh_continue(mesh, mstate, s, &ev))
      continue;

    /* run more modules */
    ev = module_event_pass;
    if(mesh->run.count > 0) {
      /* pop random element off the runnable tree */
      mstate = (struct mesh_state*)mesh->run.root->key;
      (void)rbtree_delete(&mesh->run, mstate);
    } else mstate = NULL;
  }
  if(verbosity >= VERB_ALGO) {
    mesh_stats(mesh, "mesh_run: end");
    mesh_log_list(mesh);
  }
}

void 
mesh_log_list(struct mesh_area* mesh)
{
  char buf[30];
  struct mesh_state* m;
  int num = 0;
  RBTREE_FOR(m, struct mesh_state*, &mesh->all) {
    snprintf(buf, sizeof(buf), "%d%s%s%s%s%s%s mod%d %s%s", 
      num++, (m->s.is_priming)?"p":"",  /* prime */
      (m->s.is_valrec)?"v":"",  /* prime */
      (m->s.query_flags&BIT_RD)?"RD":"",
      (m->s.query_flags&BIT_CD)?"CD":"",
      (m->super_set.count==0)?"d":"", /* detached */
      (m->sub_set.count!=0)?"c":"",  /* children */
      m->s.curmod, (m->reply_list)?"rep":"", /*hasreply*/
      (m->cb_list)?"cb":"" /* callbacks */
      ); 
    log_query_info(VERB_ALGO, buf, &m->s.qinfo);
  }
}

void 
mesh_stats(struct mesh_area* mesh, const char* str)
{
  verbose(VERB_DETAIL, "%s %u recursion states (%u with reply, "
    "%u detached), %u waiting replies, %u recursion replies "
    "sent, %d replies dropped, %d states jostled out", 
    str, (unsigned)mesh->all.count, 
    (unsigned)mesh->num_reply_states,
    (unsigned)mesh->num_detached_states,
    (unsigned)mesh->num_reply_addrs,
    (unsigned)mesh->replies_sent,
    (unsigned)mesh->stats_dropped,
    (unsigned)mesh->stats_jostled);
  if(mesh->replies_sent > 0) {
    struct timeval avg;
    timeval_divide(&avg, &mesh->replies_sum_wait, 
      mesh->replies_sent);
    log_info("average recursion processing time "
      ARG_LL "d.%6.6d sec",
      (long long)avg.tv_sec, (int)avg.tv_usec);
    log_info("histogram of recursion processing times");
    timehist_log(mesh->histogram, "recursions");
  }
}

void 
mesh_stats_clear(struct mesh_area* mesh)
{
  if(!mesh)
    return;
  mesh->replies_sent = 0;
  mesh->replies_sum_wait.tv_sec = 0;
  mesh->replies_sum_wait.tv_usec = 0;
  mesh->stats_jostled = 0;
  mesh->stats_dropped = 0;
  timehist_clear(mesh->histogram);
  mesh->ans_secure = 0;
  mesh->ans_bogus = 0;
  mesh->ans_expired = 0;
  memset(&mesh->ans_rcode[0], 0, sizeof(size_t)*UB_STATS_RCODE_NUM);
  memset(&mesh->rpz_action[0], 0, sizeof(size_t)*UB_STATS_RPZ_ACTION_NUM);
  mesh->ans_nodata = 0;
}

size_t 
mesh_get_mem(struct mesh_area* mesh)
{
  struct mesh_state* m;
  size_t s = sizeof(*mesh) + sizeof(struct timehist) +
    sizeof(struct th_buck)*mesh->histogram->num +
    sizeof(sldns_buffer) + sldns_buffer_capacity(mesh->qbuf_bak);
  RBTREE_FOR(m, struct mesh_state*, &mesh->all) {
    /* all, including m itself allocated in qstate region */
    s += regional_get_mem(m->s.region);
  }
  return s;
}

int 
mesh_detect_cycle(struct module_qstate* qstate, struct query_info* qinfo,
  uint16_t flags, int prime, int valrec)
{
  struct mesh_area* mesh = qstate->env->mesh;
  struct mesh_state* dep_m = NULL;
  dep_m = mesh_area_find(mesh, NULL, qinfo, flags, prime, valrec);
  return mesh_detect_cycle_found(qstate, dep_m);
}

void mesh_list_insert(struct mesh_state* m, struct mesh_state** fp,
        struct mesh_state** lp)
{
  /* insert as last element */
  m->prev = *lp;
  m->next = NULL;
  if(*lp)
    (*lp)->next = m;
  else  *fp = m;
  *lp = m;
}

void mesh_list_remove(struct mesh_state* m, struct mesh_state** fp,
        struct mesh_state** lp)
{
  if(m->next)
    m->next->prev = m->prev;
  else  *lp = m->prev;
  if(m->prev)
    m->prev->next = m->next;
  else  *fp = m->next;
}

void mesh_state_remove_reply(struct mesh_area* mesh, struct mesh_state* m,
  struct comm_point* cp)
{
  struct mesh_reply* n, *prev = NULL;
  n = m->reply_list;
  /* when in mesh_cleanup, it sets the reply_list to NULL, so that
   * there is no accounting twice */
  if(!n) return; /* nothing to remove, also no accounting needed */
  while(n) {
    if(n->query_reply.c == cp) {
      /* unlink it */
      if(prev) prev->next = n->next;
      else m->reply_list = n->next;
      /* delete it, but allocated in m region */
      log_assert(mesh->num_reply_addrs > 0);
      mesh->num_reply_addrs--;

      /* prev = prev; */
      n = n->next;
      continue;
    }
    prev = n;
    n = n->next;
  }
  /* it was not detached (because it had a reply list), could be now */
  if(!m->reply_list && !m->cb_list
    && m->super_set.count == 0) {
    mesh->num_detached_states++;
  }
  /* if not replies any more in mstate, it is no longer a reply_state */
  if(!m->reply_list && !m->cb_list) {
    log_assert(mesh->num_reply_states > 0);
    mesh->num_reply_states--;
  }
}


static int
apply_respip_action(struct module_qstate* qstate,
  const struct query_info* qinfo, struct respip_client_info* cinfo,
  struct respip_action_info* actinfo, struct reply_info* rep,
  struct ub_packed_rrset_key** alias_rrset,
  struct reply_info** encode_repp, struct auth_zones* az)
{
  if(qinfo->qtype != LDNS_RR_TYPE_A &&
    qinfo->qtype != LDNS_RR_TYPE_AAAA &&
    qinfo->qtype != LDNS_RR_TYPE_ANY)
    return 1;

  if(!respip_rewrite_reply(qinfo, cinfo, rep, encode_repp, actinfo,
    alias_rrset, 0, qstate->region, az, NULL))
    return 0;

  /* xxx_deny actions mean dropping the reply, unless the original reply
   * was redirected to response-ip data. */
  if((actinfo->action == respip_deny ||
    actinfo->action == respip_inform_deny) &&
    *encode_repp == rep)
    *encode_repp = NULL;

  return 1;
}

void
mesh_serve_expired_callback(void* arg)
{
  struct mesh_state* mstate = (struct mesh_state*) arg;
  struct module_qstate* qstate = &mstate->s;
  struct mesh_reply* r;
  struct mesh_area* mesh = qstate->env->mesh;
  struct dns_msg* msg;
  struct mesh_cb* c;
  struct mesh_reply* prev = NULL;
  struct sldns_buffer* prev_buffer = NULL;
  struct sldns_buffer* r_buffer = NULL;
  struct reply_info* partial_rep = NULL;
  struct ub_packed_rrset_key* alias_rrset = NULL;
  struct reply_info* encode_rep = NULL;
  struct respip_action_info actinfo;
  struct query_info* lookup_qinfo = &qstate->qinfo;
  struct query_info qinfo_tmp;
  struct timeval tv = {0, 0};
  int must_validate = (!(qstate->query_flags&BIT_CD)
    || qstate->env->cfg->ignore_cd) && qstate->env->need_to_validate;
  if(!qstate->serve_expired_data) return;
  verbose(VERB_ALGO, "Serve expired: Trying to reply with expired data");
  comm_timer_delete(qstate->serve_expired_data->timer);
  qstate->serve_expired_data->timer = NULL;
  /* If is_drop or no_cache_lookup (modules that handle their own cache e.g.,
   * subnetmod) ignore stale data from the main cache. */
  if(qstate->no_cache_lookup || qstate->is_drop) {
    verbose(VERB_ALGO,
      "Serve expired: Not allowed to look into cache for stale");
    return;
  }
  /* The following while is used instead of the `goto lookup_cache`
   * like in the worker. */
  while(1) {
    fptr_ok(fptr_whitelist_serve_expired_lookup(
      qstate->serve_expired_data->get_cached_answer));
    msg = (*qstate->serve_expired_data->get_cached_answer)(qstate,
      lookup_qinfo);
    if(!msg)
      return;
    /* Reset these in case we pass a second time from here. */
    encode_rep = msg->rep;
    memset(&actinfo, 0, sizeof(actinfo));
    actinfo.action = respip_none;
    alias_rrset = NULL;
    if((mesh->use_response_ip || mesh->use_rpz) &&
      !partial_rep && !apply_respip_action(qstate, &qstate->qinfo,
      qstate->client_info, &actinfo, msg->rep, &alias_rrset, &encode_rep,
      qstate->env->auth_zones)) {
      return;
    } else if(partial_rep &&
      !respip_merge_cname(partial_rep, &qstate->qinfo, msg->rep,
      qstate->client_info, must_validate, &encode_rep, qstate->region,
      qstate->env->auth_zones)) {
      return;
    }
    if(!encode_rep || alias_rrset) {
      if(!encode_rep) {
        /* Needs drop */
        return;
      } else {
        /* A partial CNAME chain is found. */
        partial_rep = encode_rep;
      }
    }
    /* We've found a partial reply ending with an
    * alias.  Replace the lookup qinfo for the
    * alias target and lookup the cache again to
    * (possibly) complete the reply.  As we're
    * passing the "base" reply, there will be no
    * more alias chasing. */
    if(partial_rep) {
      memset(&qinfo_tmp, 0, sizeof(qinfo_tmp));
      get_cname_target(alias_rrset, &qinfo_tmp.qname,
        &qinfo_tmp.qname_len);
      if(!qinfo_tmp.qname) {
        log_err("Serve expired: unexpected: invalid answer alias");
        return;
      }
      qinfo_tmp.qtype = qstate->qinfo.qtype;
      qinfo_tmp.qclass = qstate->qinfo.qclass;
      lookup_qinfo = &qinfo_tmp;
      continue;
    }
    break;
  }

  if(verbosity >= VERB_ALGO)
    log_dns_msg("Serve expired lookup", &qstate->qinfo, msg->rep);

  for(r = mstate->reply_list; r; r = r->next) {
    tv = r->start_time;

    /* If address info is returned, it means the action should be an
    * 'inform' variant and the information should be logged. */
    if(actinfo.addrinfo) {
      respip_inform_print(&actinfo, r->qname,
        qstate->qinfo.qtype, qstate->qinfo.qclass,
        r->local_alias, &r->query_reply.client_addr,
        r->query_reply.client_addrlen);

      if(qstate->env->cfg->stat_extended && actinfo.rpz_used) {
        if(actinfo.rpz_disabled)
          qstate->env->mesh->rpz_action[RPZ_DISABLED_ACTION]++;
        if(actinfo.rpz_cname_override)
          qstate->env->mesh->rpz_action[RPZ_CNAME_OVERRIDE_ACTION]++;
        else
          qstate->env->mesh->rpz_action[
            respip_action_to_rpz_action(actinfo.action)]++;
      }
    }

    /* Add EDE Stale Answer (RCF8914). Ignore global ede as this is
     * warning instead of an error */
    if (r->edns.edns_present && qstate->env->cfg->ede_serve_expired &&
      qstate->env->cfg->ede) {
      edns_opt_list_append_ede(&r->edns.opt_list_out,
        mstate->s.region, LDNS_EDE_STALE_ANSWER, NULL);
    }

    r_buffer = r->query_reply.c->buffer;
    if(r->query_reply.c->tcp_req_info)
      r_buffer = r->query_reply.c->tcp_req_info->spool_buffer;
    mesh_send_reply(mstate, LDNS_RCODE_NOERROR, msg->rep,
      r, r_buffer, prev, prev_buffer);
    if(r->query_reply.c->tcp_req_info)
      tcp_req_info_remove_mesh_state(r->query_reply.c->tcp_req_info, mstate);
    prev = r;
    prev_buffer = r_buffer;

    /* Account for each reply sent. */
    mesh->ans_expired++;

  }
  if(mstate->reply_list) {
    mstate->reply_list = NULL;
    if(!mstate->reply_list && !mstate->cb_list) {
      log_assert(mesh->num_reply_states > 0);
      mesh->num_reply_states--;
      if(mstate->super_set.count == 0) {
        mesh->num_detached_states++;
      }
    }
  }
  while((c = mstate->cb_list) != NULL) {
    /* take this cb off the list; so that the list can be
     * changed, eg. by adds from the callback routine */
    if(!mstate->reply_list && mstate->cb_list && !c->next) {
      /* was a reply state, not anymore */
      log_assert(qstate->env->mesh->num_reply_states > 0);
      qstate->env->mesh->num_reply_states--;
    }
    mstate->cb_list = c->next;
    if(!mstate->reply_list && !mstate->cb_list &&
      mstate->super_set.count == 0)
      qstate->env->mesh->num_detached_states++;
    mesh_do_callback(mstate, LDNS_RCODE_NOERROR, msg->rep, c, &tv);
  }
}

int mesh_jostle_exceeded(struct mesh_area* mesh)
{
  if(mesh->all.count < mesh->max_reply_states)
    return 0;
  return 1;
}

Coverage Report

Created: 2023-03-26 06:07