/***************************************************************************

 *                                  _   _ ____  _

 *  Project                     ___| | | |  _ \| |

 *                             / __| | | | |_) | |

 *                            | (__| |_| |  _ <| |___

 *                             \___|\___/|_| \_\_____|

 *

 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.

 *

 * This software is licensed as described in the file COPYING, which

 * you should have received as part of this distribution. The terms

 * are also available at https://curl.se/docs/copyright.html.

 *

 * You may opt to use, copy, modify, merge, publish, distribute and/or sell

 * copies of the Software, and permit persons to whom the Software is

 * furnished to do so, under the terms of the COPYING file.

 *

 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY

 * KIND, either express or implied.

 *

 * SPDX-License-Identifier: curl

 *

 ***************************************************************************/

#include "curl_setup.h"

/***********************************************************************

 * Only for threaded name resolves builds

 **********************************************************************/

#ifdef USE_RESOLV_THREADED

#ifdef HAVE_NETINET_IN_H

#include <netinet/in.h>

#endif

#ifdef HAVE_NETDB_H

#include <netdb.h>

#endif

#ifdef HAVE_ARPA_INET_H

#include <arpa/inet.h>

#endif

#ifdef __VMS

#include <in.h>

#include <inet.h>

#endif

#ifdef HAVE_GETADDRINFO

#define RESOLVER_ENOMEM  EAI_MEMORY  /* = WSA_NOT_ENOUGH_MEMORY on Windows */

#else

#define RESOLVER_ENOMEM  SOCKENOMEM

#endif

#include "urldata.h"

#include "cfilters.h"

#include "curl_addrinfo.h"

#include "curl_trc.h"

#include "hostip.h"

#include "httpsrr.h"

#include "url.h"

#include "multiif.h"

#include "curl_threads.h"

#include "progress.h"

#include "rand.h"

#include "select.h"

#include "thrdqueue.h"

#include "curlx/strparse.h"

#include "curlx/wait.h"

#ifdef USE_ARES

#include <ares.h>

#ifdef USE_HTTPSRR

#define USE_HTTPSRR_ARES  /* the combo */

#endif

#endif

/*

 * Curl_async_global_init()

 * Called from curl_global_init() to initialize global resolver environment.

 * Does nothing here.

 */

int Curl_async_global_init(void)

{

#if defined(USE_ARES) && defined(CARES_HAVE_ARES_LIBRARY_INIT)

  if(ares_library_init(ARES_LIB_INIT_ALL)) {

    return CURLE_FAILED_INIT;

  }

#endif

  return CURLE_OK;

}

/*

 * Curl_async_global_cleanup()

 * Called from curl_global_cleanup() to destroy global resolver environment.

 * Does nothing here.

 */

void Curl_async_global_cleanup(void)

{

#if defined(USE_ARES) && defined(CARES_HAVE_ARES_LIBRARY_INIT)

  ares_library_cleanup();

#endif

}

#ifdef CURLVERBOSE

#define CURL_ASYN_ITEM_DESC_LEN   64

#define async_item_description(x)   (x)->description

#else

#define async_item_description(x)   NULL

#endif

struct async_thrdd_item {

  struct Curl_addrinfo *res;

#ifdef CURLVERBOSE

  char description[CURL_ASYN_ITEM_DESC_LEN];

#endif

  int sock_error;

  uint32_t mid;

  uint32_t resolv_id;

  uint16_t port;

  uint8_t transport;

  uint8_t dns_queries;

#ifdef DEBUGBUILD

  uint32_t delay_ms;

  uint32_t delay_fail_ms;

#endif

  char hostname[1];

};

/* Give up reference to add_ctx */

static void async_thrdd_item_destroy(struct async_thrdd_item *item)

{

  if(item) {

    if(item->res)

      Curl_freeaddrinfo(item->res);

    curlx_free(item);

  }

}

/* Initialize context for threaded resolver */

static struct async_thrdd_item *async_thrdd_item_create(

  struct Curl_easy *data,

  uint32_t resolv_id, uint8_t dns_queries,

  const char *hostname, uint16_t port,

  uint8_t transport)

{

  size_t hostlen = strlen(hostname);

  struct async_thrdd_item *item;

  item = curlx_calloc(1, sizeof(*item) + hostlen);

  if(!item)

    return NULL;

  if(hostlen) /* NUL byte of name already in struct size */

    memcpy(item->hostname, hostname, hostlen);

  item->mid = data->mid;

  item->resolv_id = resolv_id;

  item->dns_queries = dns_queries;

  item->port = port;

  item->transport = transport;

#ifdef CURLVERBOSE

  curl_msnprintf(item->description, sizeof(item->description),

                 "[%" FMT_OFF_T "/%u] %s %s:%u",

                 data->id, item->resolv_id,

                 Curl_resolv_query_str(dns_queries),

                 item->hostname, item->port);

#endif

#ifdef DEBUGBUILD

  {

    const char *p = getenv("CURL_DBG_RESOLV_DELAY");

    if(p) {

      curl_off_t l;

      if(!curlx_str_number(&p, &l, UINT32_MAX)) {

        item->delay_ms = (uint32_t)l;

      }

    }

    p = getenv("CURL_DBG_RESOLV_FAIL_DELAY");

    if(p) {

      curl_off_t l;

      if(!curlx_str_number(&p, &l, UINT32_MAX)) {

        unsigned char c = 0;

        Curl_rand_bytes(data, FALSE, &c, 1);

        item->delay_fail_ms = (uint32_t)l + c;

      }

    }

  }

#endif

  return item;

}

#ifdef USE_HTTPSRR_ARES

static void async_thrdd_rr_done(void *user_data, ares_status_t status,

                                size_t timeouts,

                                const ares_dns_record_t *dnsrec)

{

  struct Curl_resolv_async *async = user_data;

  struct async_thrdd_ctx *thrdd = async ? &async->thrdd : NULL;

  (void)timeouts;

  if(!thrdd)

    return;

  async->dns_responses |= CURL_DNSQ_HTTPS;

  async->queries_ongoing--;

  async->done = !async->queries_ongoing;

  if((ARES_SUCCESS == status) && dnsrec)

    async->result = Curl_httpsrr_from_ares(dnsrec, &thrdd->rr.hinfo);

}

static CURLcode async_rr_start(struct Curl_easy *data,

                               struct Curl_resolv_async *async)

{

  struct async_thrdd_ctx *thrdd = &async->thrdd;

  int status;

  char *rrname = NULL;

  DEBUGASSERT(!thrdd->rr.channel);

  if(async->port != 443) {

    rrname = curl_maprintf("_%d_.https.%s", async->port, async->hostname);

    if(!rrname)

      return CURLE_OUT_OF_MEMORY;

  }

  status = ares_init_options(&thrdd->rr.channel, NULL, 0);

  if(status != ARES_SUCCESS) {

    thrdd->rr.channel = NULL;

    curlx_free(rrname);

    return CURLE_FAILED_INIT;

  }

#ifdef DEBUGBUILD

  if(getenv("CURL_DNS_SERVER")) {

    const char *servers = getenv("CURL_DNS_SERVER");

    status = ares_set_servers_ports_csv(thrdd->rr.channel, servers);

    if(status) {

      curlx_free(rrname);

      return CURLE_FAILED_INIT;

    }

  }

#endif

  memset(&thrdd->rr.hinfo, 0, sizeof(thrdd->rr.hinfo));

  thrdd->rr.hinfo.rrname = rrname;

  async->queries_ongoing++;

  ares_query_dnsrec(thrdd->rr.channel,

                    rrname ? rrname : async->hostname, ARES_CLASS_IN,

                    ARES_REC_TYPE_HTTPS,

                    async_thrdd_rr_done, async, NULL);

  CURL_TRC_DNS(data, "[HTTPS-RR] initiated request for %s",

               rrname ? rrname : async->hostname);

  return CURLE_OK;

}

#endif

void Curl_async_thrdd_shutdown(struct Curl_easy *data,

                               struct Curl_resolv_async *async)

{

  Curl_async_thrdd_destroy(data, async);

}

struct async_thrdd_match_ctx {

  uint32_t mid;

  uint32_t resolv_id;

};

static bool async_thrdd_match_item(void *qitem, void *match_data)

{

  const struct async_thrdd_match_ctx *ctx = match_data;

  struct async_thrdd_item *item = qitem;

  return (item->mid == ctx->mid) && (item->resolv_id == ctx->resolv_id);

}

void Curl_async_thrdd_destroy(struct Curl_easy *data,

                              struct Curl_resolv_async *async)

{

  (void)data;

  if(async->queries_ongoing && !async->done &&

     data->multi && data->multi->resolv_thrdq) {

    /* Remove any resolve items still queued */

    struct async_thrdd_match_ctx mctx;

    mctx.mid = data->mid;

    mctx.resolv_id = async->id;

    Curl_thrdq_clear(data->multi->resolv_thrdq,

                     async_thrdd_match_item, &mctx);

  }

#ifdef USE_HTTPSRR_ARES

  if(async->thrdd.rr.channel) {

    ares_destroy(async->thrdd.rr.channel);

    async->thrdd.rr.channel = NULL;

  }

  Curl_httpsrr_cleanup(&async->thrdd.rr.hinfo);

#endif

  async_thrdd_item_destroy(async->thrdd.res_A);

  async->thrdd.res_A = NULL;

  async_thrdd_item_destroy(async->thrdd.res_AAAA);

  async->thrdd.res_AAAA = NULL;

}

/*

 * Waits for a resolve to finish. This function should be avoided since using

 * this risk getting the multi interface to "hang".

 */

CURLcode Curl_async_await(struct Curl_easy *data, uint32_t resolv_id,

                          struct Curl_dns_entry **pdns)

{

  struct Curl_resolv_async *async = Curl_async_get(data, resolv_id);

  struct async_thrdd_ctx *thrdd = async ? &async->thrdd : NULL;

  timediff_t milli, ms;

  if(!thrdd)

    return CURLE_FAILED_INIT;

  while(async->queries_ongoing && !async->done) {

    Curl_async_thrdd_multi_process(data->multi);

    if(async->done)

      break;

    ms = curlx_ptimediff_ms(Curl_pgrs_now(data), &async->start);

    if(ms < 3)

      milli = 0;

    else if(ms <= 50)

      milli = ms / 3;

    else if(ms <= 250)

      milli = 50;

    else

      milli = 200;

    CURL_TRC_DNS(data, "await, waiting %" FMT_TIMEDIFF_T "ms", milli);

    curlx_wait_ms(milli);

  }

  return Curl_async_take_result(data, async, pdns);

}

#ifdef HAVE_GETADDRINFO

/* Process the item, using Curl_getaddrinfo_ex() */

static void async_thrdd_item_process(void *arg)

{

  struct async_thrdd_item *item = arg;

  struct addrinfo hints;

  char service[12];

  int pf = PF_INET;

  int rc;

#ifdef DEBUGBUILD

  if(item->delay_ms) {

    curlx_wait_ms(item->delay_ms);

  }

  if(item->delay_fail_ms) {

    curlx_wait_ms(item->delay_fail_ms);

    return;

  }

#endif

  memset(&hints, 0, sizeof(hints));

#ifdef CURLRES_IPV6

  if(item->dns_queries & CURL_DNSQ_AAAA) {

    pf = (item->dns_queries & CURL_DNSQ_A) ? PF_UNSPEC : PF_INET6;

  }

#endif

  hints.ai_family = pf;

  hints.ai_socktype = Curl_socktype_for_transport(item->transport);

  hints.ai_protocol = Curl_protocol_for_transport(item->transport);

#ifdef __APPLE__

  /* If we leave `ai_flags == 0` then macOS is looking for IPV4MAPPED

   * when doing AAAA queries. We do not want this "help". */

  hints.ai_flags = AI_ADDRCONFIG;

#endif

  curl_msnprintf(service, sizeof(service), "%u", item->port);

#ifdef AI_NUMERICSERV

  hints.ai_flags |= AI_NUMERICSERV;

#endif

  rc = Curl_getaddrinfo_ex(item->hostname, service, &hints, &item->res);

  if(rc) {

    item->sock_error = SOCKERRNO ? SOCKERRNO : rc;

    if(item->sock_error == 0)

      item->sock_error = RESOLVER_ENOMEM;

  }

  else {

    Curl_addrinfo_set_port(item->res, item->port);

  }

}

#else /* HAVE_GETADDRINFO */

/* Process the item, using Curl_ipv4_resolve_r() */

static void async_thrdd_item_process(void *arg)

{

  struct async_thrdd_item *item = arg;

#ifdef DEBUGBUILD

  if(item->delay_ms) {

    curlx_wait_ms(item->delay_ms);

  }

  if(item->delay_fail_ms) {

    curlx_wait_ms(item->delay_fail_ms);

    return;

  }

#endif

  item->res = Curl_ipv4_resolve_r(item->hostname, item->port);

  if(!item->res) {

    item->sock_error = SOCKERRNO;

    if(item->sock_error == 0)

      item->sock_error = RESOLVER_ENOMEM;

  }

}

#endif /* HAVE_GETADDRINFO */

#ifdef ENABLE_WAKEUP

static void async_thrdd_event(const struct curl_thrdq *tqueue,

                              Curl_thrdq_event ev,

                              void *user_data)

{

  struct Curl_multi *multi = user_data;

  (void)tqueue;

  switch(ev) {

  case CURL_THRDQ_EV_ITEM_DONE:

    (void)curl_multi_wakeup(multi);

    break;

  default:

    break;

  }

}

#else

#define async_thrdd_event   NULL

#endif

static void async_thrdd_item_free(void *item)

{

  async_thrdd_item_destroy(item);

}

/* Create a thread queue for processing resolv items */

CURLcode Curl_async_thrdd_multi_init(struct Curl_multi *multi,

                                     uint32_t min_threads,

                                     uint32_t max_threads,

                                     uint32_t idle_time_ms)

{

  CURLcode result;

  DEBUGASSERT(!multi->resolv_thrdq);

  result = Curl_thrdq_create(&multi->resolv_thrdq, "DNS", 0,

                             min_threads, max_threads, idle_time_ms,

                             async_thrdd_item_free,

                             async_thrdd_item_process,

                             async_thrdd_event,

                             multi);

#ifdef DEBUGBUILD

  if(!result) {

    const char *p = getenv("CURL_DBG_RESOLV_MAX_THREADS");

    if(p) {

      curl_off_t l;

      if(!curlx_str_number(&p, &l, UINT32_MAX)) {

        result = Curl_async_thrdd_multi_set_props(

          multi, min_threads, (uint32_t)l, idle_time_ms);

      }

    }

  }

#endif

  return result;

}

/* Tear down the thread queue, joining active threads or detaching them */

void Curl_async_thrdd_multi_destroy(struct Curl_multi *multi, bool join)

{

  if(multi->resolv_thrdq) {

#ifdef CURLVERBOSE

    CURL_TRC_DNS(multi->admin, "destroy thread queue+pool, join=%d", join);

    Curl_thrdq_trace(multi->resolv_thrdq, multi->admin);

#endif

    Curl_thrdq_destroy(multi->resolv_thrdq, join);

    multi->resolv_thrdq = NULL;

  }

}

#ifdef CURLVERBOSE

static void async_thrdd_report_item(struct Curl_easy *data,

                                    struct async_thrdd_item *item)

{

  char buf[MAX_IPADR_LEN];

  struct dynbuf tmp;

  const char *sep = "";

  const struct Curl_addrinfo *ai = item->res;

  int ai_family = (item->dns_queries & CURL_DNSQ_AAAA) ? AF_INET6 : AF_INET;

  CURLcode result;

  if(!CURL_TRC_DNS_is_verbose(data))

    return;

  curlx_dyn_init(&tmp, 1024);

  for(; ai; ai = ai->ai_next) {

    if(ai->ai_family == ai_family) {

      Curl_printable_address(ai, buf, sizeof(buf));

      result = curlx_dyn_addf(&tmp, "%s%s", sep, buf);

      if(result) {

        CURL_TRC_DNS(data, "too many IP, cannot show");

        goto out;

      }

      sep = ", ";

    }

  }

  CURL_TRC_DNS(data, "Host %s:%u resolved IPv%c: %s",

               item->hostname, item->port,

               (item->dns_queries & CURL_DNSQ_AAAA) ? '6' : '4',

               (curlx_dyn_len(&tmp) ? curlx_dyn_ptr(&tmp) : "(none)"));

out:

  curlx_dyn_free(&tmp);

}

#endif /* CURLVERBOSE */

/* Process the receiving end of the thread queue, dispatching

 * processed items to their transfer when it can still be found

 * and has an `async` state present. Otherwise, destroy the item. */

void Curl_async_thrdd_multi_process(struct Curl_multi *multi)

{

  struct Curl_easy *data;

  void *qitem;

  while(!Curl_thrdq_recv(multi->resolv_thrdq, &qitem)) {

    /* dispatch resolve result */

    struct async_thrdd_item *item = qitem;

    struct Curl_resolv_async *async = NULL;

    data = Curl_multi_get_easy(multi, item->mid);

    if(data)

      async = Curl_async_get(data, item->resolv_id);

    if(async) {

      struct async_thrdd_item **pdest = &async->thrdd.res_A;

      async->dns_responses |= item->dns_queries;

      --async->queries_ongoing;

      async->done = !async->queries_ongoing;

#ifdef CURLRES_IPV6

      if(item->dns_queries & CURL_DNSQ_AAAA)

        pdest = &async->thrdd.res_AAAA;

#endif

      if(!*pdest) {

        VERBOSE(async_thrdd_report_item(data, item));

        *pdest = item;

        item = NULL;

      }

      else

        DEBUGASSERT(0); /* should not receive duplicates here */

      Curl_multi_mark_dirty(data);

    }

    async_thrdd_item_free(item);

  }

#ifdef CURLVERBOSE

  Curl_thrdq_trace(multi->resolv_thrdq, multi->admin);

#endif

}

CURLcode Curl_async_thrdd_multi_set_props(struct Curl_multi *multi,

                                          uint32_t min_threads,

                                          uint32_t max_threads,

                                          uint32_t idle_time_ms)

{

  return Curl_thrdq_set_props(multi->resolv_thrdq, 0,

                              min_threads, max_threads, idle_time_ms);

}

static CURLcode async_thrdd_query(struct Curl_easy *data,

                                  struct Curl_resolv_async *async,

                                  uint8_t dns_queries)

{

  struct async_thrdd_item *item;

  CURLcode result;

  item = async_thrdd_item_create(data, async->id, dns_queries,

                                 async->hostname, async->port,

                                 async->transport);

  if(!item) {

    result = CURLE_OUT_OF_MEMORY;

    goto out;

  }

  CURL_TRC_DNS(data, "queueing query %s", item->description);

  result = Curl_thrdq_send(data->multi->resolv_thrdq, item,

                           async_item_description(item), async->timeout_ms);

  if(result)

    goto out;

  item = NULL;

  async->queries_ongoing++;

out:

  if(item)

    async_thrdd_item_free(item);

  return result;

}

CURLcode Curl_async_getaddrinfo(struct Curl_easy *data,

                                struct Curl_resolv_async *async)

{

  CURLcode result = CURLE_FAILED_INIT;

  void *resolver = NULL;

  if(async->queries_ongoing || async->done)

    return CURLE_FAILED_INIT;

#ifdef USE_HTTPSRR_ARES

  DEBUGASSERT(!async->thrdd.rr.channel);

  if((async->dns_queries & CURL_DNSQ_HTTPS) && !async->is_ipaddr) {

    result = async_rr_start(data, async);

    if(result)

      goto out;

    resolver = async->thrdd.rr.channel;

  }

#endif

  result = Curl_resolv_announce_start(data, resolver);

  if(result)

    return result;

#ifdef CURLRES_IPV6

  /* Do not start an AAAA query for an ipv4 address when

   * we will start an A query for it. */

  if((async->dns_queries & CURL_DNSQ_AAAA) &&

     !(async->is_ipv4addr && (async->dns_queries & CURL_DNSQ_A))) {

    result = async_thrdd_query(data, async, CURL_DNSQ_AAAA);

    if(result)

      goto out;

  }

#endif

  if(async->dns_queries & CURL_DNSQ_A) {

    result = async_thrdd_query(data, async, CURL_DNSQ_A);

    if(result)

      goto out;

  }

#ifdef CURLVERBOSE

  Curl_thrdq_trace(data->multi->resolv_thrdq, data);

#endif

out:

  if(result)

    CURL_TRC_DNS(data, "error queueing query %s:%d -> %d",

                 async->hostname, async->port, result);

  return result;

}

CURLcode Curl_async_pollset(struct Curl_easy *data,

                            struct Curl_resolv_async *async,

                            struct easy_pollset *ps)

{

  timediff_t timeout_ms;

  timeout_ms = Curl_async_timeleft_ms(data, async);

#ifdef USE_HTTPSRR_ARES

  if(async->thrdd.rr.channel) {

    CURLcode result = Curl_ares_pollset(data, async->thrdd.rr.channel, ps);

    if(result)

      return result;

    timeout_ms = Curl_ares_timeout_ms(data, async, async->thrdd.rr.channel);

  }

#else

  (void)ps;

#endif

  if(!async->done) {

#ifndef ENABLE_WAKEUP

    timediff_t stutter_ms, elapsed_ms;

    elapsed_ms = curlx_ptimediff_ms(Curl_pgrs_now(data), &async->start);

    if(elapsed_ms < 3)

      stutter_ms = 1;

    else if(elapsed_ms <= 50)

      stutter_ms = elapsed_ms / 3;

    else if(elapsed_ms <= 250)

      stutter_ms = 50;

    else

      stutter_ms = 200;

    timeout_ms = CURLMIN(stutter_ms, timeout_ms);

#endif

    Curl_expire(data, timeout_ms, EXPIRE_ASYNC_NAME);

  }

  return CURLE_OK;

}

/*

 * Curl_async_take_result() is called repeatedly to check if a previous

 * name resolve request has completed. It should also make sure to time-out if

 * the operation seems to take too long.

 */

CURLcode Curl_async_take_result(struct Curl_easy *data,

                                struct Curl_resolv_async *async,

                                struct Curl_dns_entry **pdns)

{

  struct async_thrdd_ctx *thrdd = &async->thrdd;

  struct Curl_dns_entry *dns = NULL;

  CURLcode result = CURLE_OK;

  DEBUGASSERT(pdns);

  *pdns = NULL;

  if(!async->queries_ongoing && !async->done) {

    DEBUGASSERT(0);

    return CURLE_FAILED_INIT;

  }

#ifdef USE_HTTPSRR_ARES

  /* best effort, ignore errors */

  if(thrdd->rr.channel)

    (void)Curl_ares_perform(thrdd->rr.channel, 0);

#endif

#ifndef ENABLE_WAKEUP

  Curl_async_thrdd_multi_process(data->multi);

#endif

  if(!async->done)

    return CURLE_AGAIN;

  Curl_expire_done(data, EXPIRE_ASYNC_NAME);

  if(async->result) {

    result = async->result;

    goto out;

  }

  if((thrdd->res_A && thrdd->res_A->res) ||

     (thrdd->res_AAAA && thrdd->res_AAAA->res)) {

    dns = Curl_dnscache_mk_entry2(

      data, async->dns_queries,

      thrdd->res_A ? &thrdd->res_A->res : NULL,

      thrdd->res_AAAA ? &thrdd->res_AAAA->res : NULL,

      async->hostname, async->port);

    if(!dns) {

      result = CURLE_OUT_OF_MEMORY;

      goto out;

    }

#ifdef USE_HTTPSRR_ARES

    if(thrdd->rr.channel) {

      struct Curl_https_rrinfo *lhrr = NULL;

      if(thrdd->rr.hinfo.complete) {

        lhrr = Curl_httpsrr_dup_move(&thrdd->rr.hinfo);

        if(!lhrr) {

          result = CURLE_OUT_OF_MEMORY;

          goto out;

        }

      }

      Curl_httpsrr_trace(data, lhrr);

      Curl_dns_entry_set_https_rr(dns, lhrr);

    }

#endif

  }

  if(dns) {

    *pdns = dns;

    dns = NULL;

  }

#ifdef CURLVERBOSE

  Curl_thrdq_trace(data->multi->resolv_thrdq, data);

#endif

out:

  Curl_dns_entry_unlink(data, &dns);

  Curl_async_thrdd_shutdown(data, async);

  if(!result && !*pdns)

    result = Curl_async_failed(data, async, NULL);

  if(result &&

     (result != CURLE_COULDNT_RESOLVE_HOST) &&

     (result != CURLE_COULDNT_RESOLVE_PROXY)) {

    CURL_TRC_DNS(data, "Error %d resolving %s:%d",

                 result, async->hostname, async->port);

  }

  return result;

}

static const struct Curl_addrinfo *async_thrdd_get_ai(

  const struct Curl_addrinfo *ai,

  int ai_family, unsigned int index)

{

  unsigned int i = 0;

  for(i = 0; ai; ai = ai->ai_next) {

    if(ai->ai_family == ai_family) {

      if(i == index)

        return ai;

      ++i;

    }

  }

  return NULL;

}

const struct Curl_addrinfo *Curl_async_get_ai(struct Curl_easy *data,

                                              struct Curl_resolv_async *async,

                                              int ai_family,

                                              unsigned int index)

{

  struct async_thrdd_ctx *thrdd = &async->thrdd;

  (void)data;

  switch(ai_family) {

  case AF_INET:

    if(thrdd->res_A)

      return async_thrdd_get_ai(thrdd->res_A->res, ai_family, index);

    break;

  case AF_INET6:

    if(thrdd->res_AAAA)

      return async_thrdd_get_ai(thrdd->res_AAAA->res, ai_family, index);

    break;

  default:

    break;

  }

  return NULL;

}

#ifdef USE_HTTPSRR

const struct Curl_https_rrinfo *Curl_async_get_https(

  struct Curl_easy *data,

  struct Curl_resolv_async *async)

{

#ifdef USE_HTTPSRR_ARES

  if(Curl_async_knows_https(data, async))

    return &async->thrdd.rr.hinfo;

#else

  (void)data;

  (void)async;

#endif

  return NULL;

}

bool Curl_async_knows_https(struct Curl_easy *data,

                            struct Curl_resolv_async *async)

{

  (void)data;

  if(async->dns_queries & CURL_DNSQ_HTTPS)

    return ((async->dns_responses & CURL_DNSQ_HTTPS) || async->done);

  return TRUE; /* we know it will never come */

}

#endif /* USE_HTTPSRR */

#endif /* USE_RESOLV_THREADED */