lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame] | 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_LIMITS_H |
| 20 | #include <limits.h> |
| 21 | #endif |
| 22 | |
| 23 | #include "ares.h" |
| 24 | #include "ares_private.h" |
| 25 | |
| 26 | /* return time offset between now and (future) check, in milliseconds */ |
| 27 | static long timeoffset(struct timeval *now, struct timeval *check) |
| 28 | { |
| 29 | return (check->tv_sec - now->tv_sec)*1000 + |
| 30 | (check->tv_usec - now->tv_usec)/1000; |
| 31 | } |
| 32 | |
| 33 | /* WARNING: Beware that this is linear in the number of outstanding |
| 34 | * requests! You are probably far better off just calling ares_process() |
| 35 | * once per second, rather than calling ares_timeout() to figure out |
| 36 | * when to next call ares_process(). |
| 37 | */ |
| 38 | struct timeval *ares_timeout(ares_channel channel, struct timeval *maxtv, |
| 39 | struct timeval *tvbuf) |
| 40 | { |
| 41 | struct query *query; |
| 42 | struct list_node* list_head; |
| 43 | struct list_node* list_node; |
| 44 | struct timeval now; |
| 45 | struct timeval nextstop; |
| 46 | long offset, min_offset; |
| 47 | |
| 48 | /* No queries, no timeout (and no fetch of the current time). */ |
| 49 | if (ares__is_list_empty(&(channel->all_queries))) |
| 50 | return maxtv; |
| 51 | |
| 52 | /* Find the minimum timeout for the current set of queries. */ |
| 53 | now = ares__tvnow(); |
| 54 | min_offset = -1; |
| 55 | |
| 56 | list_head = &(channel->all_queries); |
| 57 | for (list_node = list_head->next; list_node != list_head; |
| 58 | list_node = list_node->next) |
| 59 | { |
| 60 | query = list_node->data; |
| 61 | if (query->timeout.tv_sec == 0) |
| 62 | continue; |
| 63 | offset = timeoffset(&now, &query->timeout); |
| 64 | if (offset < 0) |
| 65 | offset = 0; |
| 66 | if (min_offset == -1 || offset < min_offset) |
| 67 | min_offset = offset; |
| 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) |
| 74 | { |
| 75 | int ioffset = (min_offset > (long)INT_MAX) ? INT_MAX : (int)min_offset; |
| 76 | |
| 77 | nextstop.tv_sec = ioffset/1000; |
| 78 | nextstop.tv_usec = (ioffset%1000)*1000; |
| 79 | |
| 80 | if (!maxtv || ares__timedout(maxtv, &nextstop)) |
| 81 | { |
| 82 | *tvbuf = nextstop; |
| 83 | return tvbuf; |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | return maxtv; |
| 88 | } |