res_state.c revision 331722 
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: stable/11/lib/libc/resolv/res_state.c 331722 2018-03-29 02:50:57Z eadler $
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#include "res_private.h"
41
42#undef _res
43
44struct __res_state _res;
45
46static thread_key_t res_key;
47static once_t res_init_once = ONCE_INITIALIZER;
48static int res_thr_keycreated = 0;
49
50static void
51free_res(void *ptr)
52{
53	res_state statp = ptr;
54
55	if (statp->_u._ext.ext != NULL)
56		res_ndestroy(statp);
57	free(statp);
58}
59
60static void
61res_keycreate(void)
62{
63	res_thr_keycreated = thr_keycreate(&res_key, free_res) == 0;
64}
65
66static res_state
67res_check_reload(res_state statp)
68{
69	struct timespec now;
70	struct stat sb;
71	struct __res_state_ext *ext;
72
73	if ((statp->options & RES_INIT) == 0) {
74		return (statp);
75	}
76
77	ext = statp->_u._ext.ext;
78	if (ext == NULL || ext->reload_period == 0) {
79		return (statp);
80	}
81
82	if (clock_gettime(CLOCK_MONOTONIC_FAST, &now) != 0 ||
83	    (now.tv_sec - ext->conf_stat) < ext->reload_period) {
84		return (statp);
85	}
86
87	ext->conf_stat = now.tv_sec;
88	if (stat(_PATH_RESCONF, &sb) == 0 &&
89	    (sb.st_mtim.tv_sec  != ext->conf_mtim.tv_sec ||
90	     sb.st_mtim.tv_nsec != ext->conf_mtim.tv_nsec)) {
91		statp->options &= ~RES_INIT;
92	}
93
94	return (statp);
95}
96
97res_state
98__res_state(void)
99{
100	res_state statp;
101
102	if (thr_main() != 0)
103		return res_check_reload(&_res);
104
105	if (thr_once(&res_init_once, res_keycreate) != 0 ||
106	    !res_thr_keycreated)
107		return (&_res);
108
109	statp = thr_getspecific(res_key);
110	if (statp != NULL)
111		return res_check_reload(statp);
112	statp = calloc(1, sizeof(*statp));
113	if (statp == NULL)
114		return (&_res);
115#ifdef __BIND_RES_TEXT
116	statp->options = RES_TIMEOUT;			/* Motorola, et al. */
117#endif
118	if (thr_setspecific(res_key, statp) == 0)
119		return (statp);
120	free(statp);
121	return (&_res);
122}
123