1
2/* Copyright 1998 by the Massachusetts Institute of Technology.
3 *
4 * Permission to use, copy, modify, and distribute this
5 * software and its documentation for any purpose and without
6 * fee is hereby granted, provided that the above copyright
7 * notice appear in all copies and that both that copyright
8 * notice and this permission notice appear in supporting
9 * documentation, and that the name of M.I.T. not be used in
10 * advertising or publicity pertaining to distribution of the
11 * software without specific, written prior permission.
12 * M.I.T. makes no representations about the suitability of
13 * this software for any purpose.  It is provided "as is"
14 * without express or implied warranty.
15 */
16
17#include "ares_setup.h"
18
19#ifdef HAVE_SYS_TIME_H
20#include <sys/time.h>
21#endif
22
23#include <time.h>
24
25#include "ares.h"
26#include "ares_private.h"
27
28/* WARNING: Beware that this is linear in the number of outstanding
29 * requests! You are probably far better off just calling ares_process()
30 * once per second, rather than calling ares_timeout() to figure out
31 * when to next call ares_process().
32 */
33struct timeval *ares_timeout(ares_channel channel, struct timeval *maxtv,
34                             struct timeval *tvbuf)
35{
36  struct query *query;
37  struct list_node* list_head;
38  struct list_node* list_node;
39  struct timeval now;
40  struct timeval nextstop;
41  long offset, min_offset;
42
43  /* No queries, no timeout (and no fetch of the current time). */
44  if (ares__is_list_empty(&(channel->all_queries)))
45    return maxtv;
46
47  /* Find the minimum timeout for the current set of queries. */
48  now = ares__tvnow();
49  min_offset = -1;
50
51  list_head = &(channel->all_queries);
52  for (list_node = list_head->next; list_node != list_head;
53       list_node = list_node->next)
54    {
55      query = list_node->data;
56      if (query->timeout.tv_sec == 0)
57        continue;
58      offset = ares__timeoffset(&now, &query->timeout);
59      if (offset < 0)
60        offset = 0;
61      if (min_offset == -1 || offset < min_offset)
62        min_offset = offset;
63    }
64
65  if(min_offset != -1) {
66    nextstop.tv_sec = min_offset/1000;
67    nextstop.tv_usec = (min_offset%1000)*1000;
68  }
69
70  /* If we found a minimum timeout and it's sooner than the one specified in
71   * maxtv (if any), return it.  Otherwise go with maxtv.
72   */
73  if (min_offset != -1 && (!maxtv || ares__timedout(maxtv, &nextstop)))
74    {
75      *tvbuf = nextstop;
76      return tvbuf;
77    }
78  else
79    return maxtv;
80}
81