res_state.c revision 289315 
1/*-
2 * Copyright (c) 2006 The FreeBSD Project. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 *
25 * $FreeBSD: head/lib/libc/resolv/res_state.c 289315 2015-10-14 14:26:44Z vangyzen $
26 */
27
28#include <sys/types.h>
29#include <sys/stat.h>
30#include <sys/time.h>
31#include <netinet/in.h>
32#include <arpa/nameser.h>
33#include <resolv.h>
34#include <stdlib.h>
35
36#include "namespace.h"
37#include "reentrant.h"
38#include "un-namespace.h"
39
40#undef _res
41
42struct __res_state _res;
43
44static thread_key_t res_key;
45static once_t res_init_once = ONCE_INITIALIZER;
46static int res_thr_keycreated = 0;
47
48static void
49free_res(void *ptr)
50{
51	res_state statp = ptr;
52
53	if (statp->_u._ext.ext != NULL)
54		res_ndestroy(statp);
55	free(statp);
56}
57
58static void
59res_keycreate(void)
60{
61	res_thr_keycreated = thr_keycreate(&res_key, free_res) == 0;
62}
63
64static res_state
65res_check_reload(res_state statp)
66{
67	struct timespec now;
68	struct stat sb;
69
70	if ((statp->options & RES_INIT) == 0 || statp->reload_period == 0) {
71		return (statp);
72	}
73
74	if (clock_gettime(CLOCK_MONOTONIC_FAST, &now) != 0 ||
75	    (now.tv_sec - statp->conf_stat) < statp->reload_period) {
76		return (statp);
77	}
78
79	statp->conf_stat = now.tv_sec;
80	if (stat(_PATH_RESCONF, &sb) == 0 &&
81	    (sb.st_mtim.tv_sec  != statp->conf_mtim.tv_sec ||
82	     sb.st_mtim.tv_nsec != statp->conf_mtim.tv_nsec)) {
83		statp->options &= ~RES_INIT;
84	}
85
86	return (statp);
87}
88
89res_state
90__res_state(void)
91{
92	res_state statp;
93
94	if (thr_main() != 0)
95		return res_check_reload(&_res);
96
97	if (thr_once(&res_init_once, res_keycreate) != 0 ||
98	    !res_thr_keycreated)
99		return (&_res);
100
101	statp = thr_getspecific(res_key);
102	if (statp != NULL)
103		return res_check_reload(statp);
104	statp = calloc(1, sizeof(*statp));
105	if (statp == NULL)
106		return (&_res);
107#ifdef __BIND_RES_TEXT
108	statp->options = RES_TIMEOUT;			/* Motorola, et al. */
109#endif
110	if (thr_setspecific(res_key, statp) == 0)
111		return (statp);
112	free(statp);
113	return (&_res);
114}
115