/* MIT License
 *
 * Copyright (c) 1998 Massachusetts Institute of Technology
 * Copyright (c) The c-ares project and its contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * SPDX-License-Identifier: MIT
 */

#include "ares_setup.h"

#ifdef HAVE_LIMITS_H
#  include <limits.h>
#endif

#include "ares.h"
#include "ares_private.h"

/* return time offset between now and (future) check, in milliseconds */
static long timeoffset(const struct timeval *now, const struct timeval *check)
{
  return (check->tv_sec - now->tv_sec) * 1000 +
         (check->tv_usec - now->tv_usec) / 1000;
}

struct timeval *ares_timeout(const struct ares_channeldata *channel,
                             struct timeval *maxtv,
                             struct timeval *tvbuf)
{
  struct query       *query;
  ares__slist_node_t *node;
  struct timeval      now;
  long                offset;

  /* The minimum timeout of all queries is always the first entry in
   * channel->queries_by_timeout */
  node = ares__slist_node_first(channel->queries_by_timeout);
  /* no queries/timeout */
  if (node == NULL) {
    return maxtv; /* <-- maxtv can be null though, hrm */
  }

  query = ares__slist_node_val(node);

  now = ares__tvnow();

  offset = timeoffset(&now, &query->timeout);
  if (offset < 0) {
    offset = 0;
  }
  if (offset > (long)INT_MAX) {
    offset = INT_MAX;
  }

  tvbuf->tv_sec  = offset / 1000;
  tvbuf->tv_usec = (offset % 1000) * 1000;

  if (maxtv == NULL) {
    return tvbuf;
  }

  /* Return the minimum time between maxtv and tvbuf */

  if (tvbuf->tv_sec > maxtv->tv_sec) {
    return maxtv;
  }
  if (tvbuf->tv_sec < maxtv->tv_sec) {
    return tvbuf;
  }

  if (tvbuf->tv_usec > maxtv->tv_usec) {
    return maxtv;
  }

  return tvbuf;
}
