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

 *                                  _   _ ____  _

 *  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"

#ifndef CURL_DISABLE_HTTP

#include "urldata.h"

#include <curl/curl.h>

#include "curl_trc.h"

#include "cfilters.h"

#include "connect.h"

#include "hostip.h"

#include "multiif.h"

#include "cf-https-connect.h"

#include "http2.h"

#include "select.h"

#include "vquic/vquic.h"

typedef enum {

  CF_HC_INIT,

  CF_HC_CONNECT,

  CF_HC_SUCCESS,

  CF_HC_FAILURE

} cf_hc_state;

struct cf_hc_baller {

  const char *name;

  struct Curl_cfilter *cf;

  CURLcode result;

  struct curltime started;

  int reply_ms;

  uint8_t transport;

  enum alpnid alpn_id;

  BIT(shutdown);

};

static void cf_hc_baller_reset(struct cf_hc_baller *b,

                               struct Curl_easy *data)

{

  if(b->cf) {

    Curl_conn_cf_close(b->cf, data);

    Curl_conn_cf_discard_chain(&b->cf, data);

    b->cf = NULL;

  }

  b->result = CURLE_OK;

  b->reply_ms = -1;

}

static bool cf_hc_baller_is_active(struct cf_hc_baller *b)

{

  return b->cf && !b->result;

}

static bool cf_hc_baller_has_started(struct cf_hc_baller *b)

{

  return !!b->cf;

}

static int cf_hc_baller_reply_ms(struct cf_hc_baller *b,

                                 struct Curl_easy *data)

{

  if(b->cf && (b->reply_ms < 0))

    b->cf->cft->query(b->cf, data, CF_QUERY_CONNECT_REPLY_MS,

                      &b->reply_ms, NULL);

  return b->reply_ms;

}

static bool cf_hc_baller_data_pending(struct cf_hc_baller *b,

                                      const struct Curl_easy *data)

{

  return b->cf && !b->result && b->cf->cft->has_data_pending(b->cf, data);

}

static bool cf_hc_baller_needs_flush(struct cf_hc_baller *b,

                                     struct Curl_easy *data)

{

  return b->cf && !b->result && Curl_conn_cf_needs_flush(b->cf, data);

}

static CURLcode cf_hc_baller_cntrl(struct cf_hc_baller *b,

                                   struct Curl_easy *data,

                                   int event, int arg1, void *arg2)

{

  if(b->cf && !b->result)

    return Curl_conn_cf_cntrl(b->cf, data, FALSE, event, arg1, arg2);

  return CURLE_OK;

}

struct cf_hc_ctx {

  cf_hc_state state;

  struct curltime started;  /* when connect started */

  CURLcode result;          /* overall result */

  struct cf_hc_baller ballers[2];

  size_t baller_count;

  timediff_t soft_eyeballs_timeout_ms;

  timediff_t hard_eyeballs_timeout_ms;

};

static void cf_hc_baller_assign(struct cf_hc_baller *b,

                                enum alpnid alpn_id,

                                uint8_t def_transport)

{

  b->alpn_id = alpn_id;

  b->transport = def_transport;

  switch(b->alpn_id) {

  case ALPN_h3:

    b->name = "h3";

    b->transport = TRNSPRT_QUIC;

    break;

  case ALPN_h2:

    b->name = "h2";

    break;

  case ALPN_h1:

    b->name = "h1";

    break;

  default:

    b->result = CURLE_FAILED_INIT;

    break;

  }

}

static void cf_hc_baller_init(struct cf_hc_baller *b,

                              struct Curl_cfilter *cf,

                              struct Curl_easy *data,

                              uint8_t transport)

{

  struct Curl_cfilter *save = cf->next;

  cf->next = NULL;

  b->started = curlx_now();

  switch(b->alpn_id) {

  case ALPN_h3:

    transport = TRNSPRT_QUIC;

    break;

  default:

    break;

  }

  if(!b->result)

    b->result = Curl_cf_setup_insert_after(cf, data, transport,

                                           CURL_CF_SSL_ENABLE);

  b->cf = cf->next;

  cf->next = save;

}

static CURLcode cf_hc_baller_connect(struct cf_hc_baller *b,

                                     struct Curl_cfilter *cf,

                                     struct Curl_easy *data,

                                     bool *done)

{

  struct Curl_cfilter *save = cf->next;

  cf->next = b->cf;

  b->result = Curl_conn_cf_connect(cf->next, data, done);

  b->cf = cf->next; /* it might mutate */

  cf->next = save;

  return b->result;

}

static void cf_hc_reset(struct Curl_cfilter *cf, struct Curl_easy *data)

{

  struct cf_hc_ctx *ctx = cf->ctx;

  size_t i;

  if(ctx) {

    for(i = 0; i < ctx->baller_count; ++i)

      cf_hc_baller_reset(&ctx->ballers[i], data);

    ctx->state = CF_HC_INIT;

    ctx->result = CURLE_OK;

    ctx->hard_eyeballs_timeout_ms = data->set.happy_eyeballs_timeout;

    ctx->soft_eyeballs_timeout_ms = data->set.happy_eyeballs_timeout / 4;

  }

}

static CURLcode baller_connected(struct Curl_cfilter *cf,

                                 struct Curl_easy *data,

                                 struct cf_hc_baller *winner)

{

  struct cf_hc_ctx *ctx = cf->ctx;

  CURLcode result = CURLE_OK;

  int reply_ms;

  size_t i;

  DEBUGASSERT(winner->cf);

  for(i = 0; i < ctx->baller_count; ++i)

    if(winner != &ctx->ballers[i])

      cf_hc_baller_reset(&ctx->ballers[i], data);

  reply_ms = cf_hc_baller_reply_ms(winner, data);

  if(reply_ms >= 0)

    CURL_TRC_CF(data, cf, "connect+handshake %s: %dms, 1st data: %dms",

                winner->name,

                (int)curlx_timediff_ms(curlx_now(),

                                       winner->started), reply_ms);

  else

    CURL_TRC_CF(data, cf, "deferred handshake %s: %dms",

                winner->name, (int)curlx_timediff_ms(curlx_now(),

                                                     winner->started));

  /* install the winning filter below this one. */

  cf->next = winner->cf;

  winner->cf = NULL;

#ifdef USE_NGHTTP2

  {

    /* Using nghttp2, we add the filter "below" us, so when the conn

     * closes, we tear it down for a fresh reconnect */

    const char *alpn = Curl_conn_cf_get_alpn_negotiated(cf->next, data);

    if(alpn && !strcmp("h2", alpn)) {

      result = Curl_http2_switch_at(cf, data);

      if(result) {

        ctx->state = CF_HC_FAILURE;

        ctx->result = result;

        return result;

      }

    }

  }

#endif

  ctx->state = CF_HC_SUCCESS;

  cf->connected = TRUE;

  return result;

}

static bool time_to_start_next(struct Curl_cfilter *cf,

                               struct Curl_easy *data,

                               size_t idx, struct curltime now)

{

  struct cf_hc_ctx *ctx = cf->ctx;

  timediff_t elapsed_ms;

  size_t i;

  if(idx >= ctx->baller_count)

    return FALSE;

  if(cf_hc_baller_has_started(&ctx->ballers[idx]))

    return FALSE;

  for(i = 0; i < idx; i++) {

    if(!ctx->ballers[i].result)

      break;

  }

  if(i == idx) {

    CURL_TRC_CF(data, cf, "all previous attempts failed, starting %s",

                ctx->ballers[idx].name);

    return TRUE;

  }

  elapsed_ms = curlx_timediff_ms(now, ctx->started);

  if(elapsed_ms >= ctx->hard_eyeballs_timeout_ms) {

    CURL_TRC_CF(data, cf, "hard timeout of %" FMT_TIMEDIFF_T "ms reached, "

                "starting %s",

                ctx->hard_eyeballs_timeout_ms, ctx->ballers[idx].name);

    return TRUE;

  }

  if((idx > 0) && (elapsed_ms >= ctx->soft_eyeballs_timeout_ms)) {

    if(cf_hc_baller_reply_ms(&ctx->ballers[idx - 1], data) < 0) {

      CURL_TRC_CF(data, cf, "soft timeout of %" FMT_TIMEDIFF_T "ms reached, "

                  "%s has not seen any data, starting %s",

                  ctx->soft_eyeballs_timeout_ms,

                  ctx->ballers[idx - 1].name, ctx->ballers[idx].name);

      return TRUE;

    }

    /* set the effective hard timeout again */

    Curl_expire(data, ctx->hard_eyeballs_timeout_ms - elapsed_ms,

                EXPIRE_ALPN_EYEBALLS);

  }

  return FALSE;

}

static CURLcode cf_hc_connect(struct Curl_cfilter *cf,

                              struct Curl_easy *data,

                              bool *done)

{

  struct cf_hc_ctx *ctx = cf->ctx;

  struct curltime now;

  CURLcode result = CURLE_OK;

  size_t i, failed_ballers;

  if(cf->connected) {

    *done = TRUE;

    return CURLE_OK;

  }

  *done = FALSE;

  now = curlx_now();

  switch(ctx->state) {

  case CF_HC_INIT:

    DEBUGASSERT(!cf->next);

    for(i = 0; i < ctx->baller_count; i++)

      DEBUGASSERT(!ctx->ballers[i].cf);

    CURL_TRC_CF(data, cf, "connect, init");

    ctx->started = now;

    cf_hc_baller_init(&ctx->ballers[0], cf, data, ctx->ballers[0].transport);

    if(ctx->baller_count > 1) {

      Curl_expire(data, ctx->soft_eyeballs_timeout_ms, EXPIRE_ALPN_EYEBALLS);

      CURL_TRC_CF(data, cf, "set next attempt to start in %" FMT_TIMEDIFF_T

                  "ms", ctx->soft_eyeballs_timeout_ms);

    }

    ctx->state = CF_HC_CONNECT;

    FALLTHROUGH();

  case CF_HC_CONNECT:

    if(cf_hc_baller_is_active(&ctx->ballers[0])) {

      result = cf_hc_baller_connect(&ctx->ballers[0], cf, data, done);

      if(!result && *done) {

        result = baller_connected(cf, data, &ctx->ballers[0]);

        goto out;

      }

    }

    if(time_to_start_next(cf, data, 1, now)) {

      cf_hc_baller_init(&ctx->ballers[1], cf, data, ctx->ballers[1].transport);

    }

    if((ctx->baller_count > 1) && cf_hc_baller_is_active(&ctx->ballers[1])) {

      CURL_TRC_CF(data, cf, "connect, check %s", ctx->ballers[1].name);

      result = cf_hc_baller_connect(&ctx->ballers[1], cf, data, done);

      if(!result && *done) {

        result = baller_connected(cf, data, &ctx->ballers[1]);

        goto out;

      }

    }

    failed_ballers = 0;

    for(i = 0; i < ctx->baller_count; i++) {

      if(ctx->ballers[i].result)

        ++failed_ballers;

    }

    if(failed_ballers == ctx->baller_count) {

      /* all have failed. we give up */

      CURL_TRC_CF(data, cf, "connect, all attempts failed");

      for(i = 0; i < ctx->baller_count; i++) {

        if(ctx->ballers[i].result) {

          result = ctx->ballers[i].result;

          break;

        }

      }

      ctx->state = CF_HC_FAILURE;

      goto out;

    }

    result = CURLE_OK;

    *done = FALSE;

    break;

  case CF_HC_FAILURE:

    result = ctx->result;

    cf->connected = FALSE;

    *done = FALSE;

    break;

  case CF_HC_SUCCESS:

    result = CURLE_OK;

    cf->connected = TRUE;

    *done = TRUE;

    break;

  }

out:

  CURL_TRC_CF(data, cf, "connect -> %d, done=%d", result, *done);

  return result;

}

static CURLcode cf_hc_shutdown(struct Curl_cfilter *cf,

                               struct Curl_easy *data, bool *done)

{

  struct cf_hc_ctx *ctx = cf->ctx;

  size_t i;

  CURLcode result = CURLE_OK;

  DEBUGASSERT(data);

  if(cf->connected) {

    *done = TRUE;

    return CURLE_OK;

  }

  /* shutdown all ballers that have not done so already. If one fails,

   * continue shutting down others until all are shutdown. */

  for(i = 0; i < ctx->baller_count; i++) {

    struct cf_hc_baller *b = &ctx->ballers[i];

    bool bdone = FALSE;

    if(!cf_hc_baller_is_active(b) || b->shutdown)

      continue;

    b->result = b->cf->cft->do_shutdown(b->cf, data, &bdone);

    if(b->result || bdone)

      b->shutdown = TRUE; /* treat a failed shutdown as done */

  }

  *done = TRUE;

  for(i = 0; i < ctx->baller_count; i++) {

    if(!ctx->ballers[i].shutdown)

      *done = FALSE;

  }

  if(*done) {

    for(i = 0; i < ctx->baller_count; i++) {

      if(ctx->ballers[i].result)

        result = ctx->ballers[i].result;

    }

  }

  CURL_TRC_CF(data, cf, "shutdown -> %d, done=%d", result, *done);

  return result;

}

static CURLcode cf_hc_adjust_pollset(struct Curl_cfilter *cf,

                                     struct Curl_easy *data,

                                     struct easy_pollset *ps)

{

  CURLcode result = CURLE_OK;

  if(!cf->connected) {

    struct cf_hc_ctx *ctx = cf->ctx;

    size_t i;

    for(i = 0; (i < ctx->baller_count) && !result; i++) {

      struct cf_hc_baller *b = &ctx->ballers[i];

      if(!cf_hc_baller_is_active(b))

        continue;

      result = Curl_conn_cf_adjust_pollset(b->cf, data, ps);

    }

    CURL_TRC_CF(data, cf, "adjust_pollset -> %d, %d socks", result, ps->n);

  }

  return result;

}

static bool cf_hc_data_pending(struct Curl_cfilter *cf,

                               const struct Curl_easy *data)

{

  struct cf_hc_ctx *ctx = cf->ctx;

  size_t i;

  if(cf->connected)

    return cf->next->cft->has_data_pending(cf->next, data);

  for(i = 0; i < ctx->baller_count; i++)

    if(cf_hc_baller_data_pending(&ctx->ballers[i], data))

      return TRUE;

  return FALSE;

}

static struct curltime cf_get_max_baller_time(struct Curl_cfilter *cf,

                                              struct Curl_easy *data,

                                              int query)

{

  struct cf_hc_ctx *ctx = cf->ctx;

  struct curltime t, tmax;

  size_t i;

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

  for(i = 0; i < ctx->baller_count; i++) {

    struct Curl_cfilter *cfb = ctx->ballers[i].cf;

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

    if(cfb && !cfb->cft->query(cfb, data, query, NULL, &t)) {

      if((t.tv_sec || t.tv_usec) && curlx_timediff_us(t, tmax) > 0)

        tmax = t;

    }

  }

  return tmax;

}

static CURLcode cf_hc_query(struct Curl_cfilter *cf,

                            struct Curl_easy *data,

                            int query, int *pres1, void *pres2)

{

  struct cf_hc_ctx *ctx = cf->ctx;

  size_t i;

  if(!cf->connected) {

    switch(query) {

    case CF_QUERY_TIMER_CONNECT: {

      struct curltime *when = pres2;

      *when = cf_get_max_baller_time(cf, data, CF_QUERY_TIMER_CONNECT);

      return CURLE_OK;

    }

    case CF_QUERY_TIMER_APPCONNECT: {

      struct curltime *when = pres2;

      *when = cf_get_max_baller_time(cf, data, CF_QUERY_TIMER_APPCONNECT);

      return CURLE_OK;

    }

    case CF_QUERY_NEED_FLUSH: {

      for(i = 0; i < ctx->baller_count; i++)

        if(cf_hc_baller_needs_flush(&ctx->ballers[i], data)) {

          *pres1 = TRUE;

          return CURLE_OK;

        }

      break;

    }

    default:

      break;

    }

  }

  return cf->next ?

    cf->next->cft->query(cf->next, data, query, pres1, pres2) :

    CURLE_UNKNOWN_OPTION;

}

static CURLcode cf_hc_cntrl(struct Curl_cfilter *cf,

                            struct Curl_easy *data,

                            int event, int arg1, void *arg2)

{

  struct cf_hc_ctx *ctx = cf->ctx;

  CURLcode result = CURLE_OK;

  size_t i;

  if(!cf->connected) {

    for(i = 0; i < ctx->baller_count; i++) {

      result = cf_hc_baller_cntrl(&ctx->ballers[i], data, event, arg1, arg2);

      if(result && (result != CURLE_AGAIN))

        goto out;

    }

    result = CURLE_OK;

  }

out:

  return result;

}

static void cf_hc_close(struct Curl_cfilter *cf, struct Curl_easy *data)

{

  CURL_TRC_CF(data, cf, "close");

  cf_hc_reset(cf, data);

  cf->connected = FALSE;

  if(cf->next) {

    cf->next->cft->do_close(cf->next, data);

    Curl_conn_cf_discard_chain(&cf->next, data);

  }

}

static void cf_hc_destroy(struct Curl_cfilter *cf, struct Curl_easy *data)

{

  struct cf_hc_ctx *ctx = cf->ctx;

  (void)data;

  CURL_TRC_CF(data, cf, "destroy");

  cf_hc_reset(cf, data);

  Curl_safefree(ctx);

}

struct Curl_cftype Curl_cft_http_connect = {

  "HTTPS-CONNECT",

  0,

  CURL_LOG_LVL_NONE,

  cf_hc_destroy,

  cf_hc_connect,

  cf_hc_close,

  cf_hc_shutdown,

  cf_hc_adjust_pollset,

  cf_hc_data_pending,

  Curl_cf_def_send,

  Curl_cf_def_recv,

  cf_hc_cntrl,

  Curl_cf_def_conn_is_alive,

  Curl_cf_def_conn_keep_alive,

  cf_hc_query,

};

static CURLcode cf_hc_create(struct Curl_cfilter **pcf,

                             struct Curl_easy *data,

                             enum alpnid *alpnids, size_t alpn_count,

                             uint8_t def_transport)

{

  struct Curl_cfilter *cf = NULL;

  struct cf_hc_ctx *ctx;

  CURLcode result = CURLE_OK;

  size_t i;

  ctx = curlx_calloc(1, sizeof(*ctx));

  if(!ctx) {

    result = CURLE_OUT_OF_MEMORY;

    goto out;

  }

  DEBUGASSERT(alpnids);

  DEBUGASSERT(alpn_count);

  DEBUGASSERT(alpn_count <= CURL_ARRAYSIZE(ctx->ballers));

  if(!alpn_count || (alpn_count > CURL_ARRAYSIZE(ctx->ballers))) {

    failf(data, "https-connect filter create with unsupported %zu ALPN ids",

          alpn_count);

    result = CURLE_FAILED_INIT;

    goto out;

  }

  for(i = 0; i < alpn_count; ++i)

    cf_hc_baller_assign(&ctx->ballers[i], alpnids[i], def_transport);

  for(; i < CURL_ARRAYSIZE(ctx->ballers); ++i)

    ctx->ballers[i].alpn_id = ALPN_none;

  ctx->baller_count = alpn_count;

  result = Curl_cf_create(&cf, &Curl_cft_http_connect, ctx);

  if(result)

    goto out;

  ctx = NULL;

  cf_hc_reset(cf, data);

out:

  *pcf = result ? NULL : cf;

  curlx_free(ctx);

  return result;

}

static CURLcode cf_http_connect_add(struct Curl_easy *data,

                                    struct connectdata *conn,

                                    int sockindex,

                                    enum alpnid *alpn_ids, size_t alpn_count,

                                    uint8_t def_transport)

{

  struct Curl_cfilter *cf;

  CURLcode result = CURLE_OK;

  DEBUGASSERT(data);

  result = cf_hc_create(&cf, data, alpn_ids, alpn_count, def_transport);

  if(result)

    goto out;

  Curl_conn_cf_add(data, conn, sockindex, cf);

out:

  return result;

}

static bool cf_https_alpns_contain(enum alpnid id,

                                   enum alpnid *list, size_t len)

{

  size_t i;

  for(i = 0; i < len; ++i) {

    if(id == list[i])

      return TRUE;

  }

  return FALSE;

}

CURLcode Curl_cf_https_setup(struct Curl_easy *data,

                             struct connectdata *conn,

                             int sockindex)

{

  enum alpnid alpn_ids[2];

  size_t alpn_count = 0;

  CURLcode result = CURLE_OK;

  struct Curl_cfilter cf_fake, *cf = NULL;

  (void)sockindex;

  /* we want to log for the filter before we create it, fake it. */

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

  cf_fake.cft = &Curl_cft_http_connect;

  cf = &cf_fake;

  if(conn->bits.tls_enable_alpn) {

#ifdef USE_HTTPSRR

    /* Is there an HTTPSRR use its ALPNs here.

     * We are here after having selected a connection to a host+port and

     * can no longer change that. Any HTTPSRR advice for other hosts and ports

     * we need to ignore. */

    struct Curl_dns_entry *dns = data->state.dns[sockindex];

    struct Curl_https_rrinfo *rr = dns ? dns->hinfo : NULL;

    if(rr && !rr->no_def_alpn &&  /* ALPNs are defaults */

       (!rr->target ||      /* for same host */

        !rr->target[0] ||

        (rr->target[0] == '.' &&

         !rr->target[1])) &&

       (rr->port < 0 ||    /* for same port */

        rr->port == conn->remote_port)) {

      size_t i;

      for(i = 0; i < CURL_ARRAYSIZE(rr->alpns) &&

                 alpn_count < CURL_ARRAYSIZE(alpn_ids); ++i) {

        enum alpnid alpn = rr->alpns[i];

        if(cf_https_alpns_contain(alpn, alpn_ids, alpn_count))

          continue;

        switch(alpn) {

        case ALPN_h3:

          if(Curl_conn_may_http3(data, conn, conn->transport_wanted))

            break;  /* not possible */

          if(data->state.http_neg.allowed & CURL_HTTP_V3x) {

            CURL_TRC_CF(data, cf, "adding h3 via HTTPS-RR");

            alpn_ids[alpn_count++] = alpn;

          }

          break;

        case ALPN_h2:

          if(data->state.http_neg.allowed & CURL_HTTP_V2x) {

            CURL_TRC_CF(data, cf, "adding h2 via HTTPS-RR");

            alpn_ids[alpn_count++] = alpn;

          }

          break;

        case ALPN_h1:

          if(data->state.http_neg.allowed & CURL_HTTP_V1x) {

            CURL_TRC_CF(data, cf, "adding h1 via HTTPS-RR");

            alpn_ids[alpn_count++] = alpn;

          }

          break;

        default: /* ignore */

          break;

        }

      }

    }

#endif

    if((alpn_count < CURL_ARRAYSIZE(alpn_ids)) &&

       (data->state.http_neg.wanted & CURL_HTTP_V3x) &&

       !cf_https_alpns_contain(ALPN_h3, alpn_ids, alpn_count)) {

      result = Curl_conn_may_http3(data, conn, conn->transport_wanted);

      if(!result) {

        CURL_TRC_CF(data, cf, "adding wanted h3");

        alpn_ids[alpn_count++] = ALPN_h3;

      }

      else if(data->state.http_neg.wanted == CURL_HTTP_V3x)

        goto out; /* only h3 allowed, not possible, error out */

    }

    if((alpn_count < CURL_ARRAYSIZE(alpn_ids)) &&

       (data->state.http_neg.wanted & CURL_HTTP_V2x) &&

       !cf_https_alpns_contain(ALPN_h2, alpn_ids, alpn_count)) {

      CURL_TRC_CF(data, cf, "adding wanted h2");

      alpn_ids[alpn_count++] = ALPN_h2;

    }

    else if((alpn_count < CURL_ARRAYSIZE(alpn_ids)) &&

            (data->state.http_neg.wanted & CURL_HTTP_V1x) &&

            !cf_https_alpns_contain(ALPN_h1, alpn_ids, alpn_count)) {

      CURL_TRC_CF(data, cf, "adding wanted h1");

      alpn_ids[alpn_count++] = ALPN_h1;

    }

  }

  /* If we identified ALPNs to use, install our filter. Otherwise,

   * install nothing, so our call will use a default connect setup. */

  if(alpn_count) {

    result = cf_http_connect_add(data, conn, sockindex,

                                 alpn_ids, alpn_count,

                                 conn->transport_wanted);

  }

out:

  return result;

}

#endif /* !CURL_DISABLE_HTTP */