1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2006 The FreeBSD Project. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 * $FreeBSD$
28 */
29
30#include <sys/types.h>
31#include <sys/stat.h>
32#include <sys/time.h>
33#include <netinet/in.h>
34#include <arpa/nameser.h>
35#include <resolv.h>
36#include <stdlib.h>
37
38#include "namespace.h"
39#include "reentrant.h"
40#include "un-namespace.h"
41
42#include "res_private.h"
43
44#undef _res
45
46struct __res_state _res;
47
48static thread_key_t res_key;
49static once_t res_init_once = ONCE_INITIALIZER;
50static int res_thr_keycreated = 0;
51
52static void
53free_res(void *ptr)
54{
55	res_state statp = ptr;
56
57	if (statp->_u._ext.ext != NULL)
58		res_ndestroy(statp);
59	free(statp);
60}
61
62static void
63res_keycreate(void)
64{
65	res_thr_keycreated = thr_keycreate(&res_key, free_res) == 0;
66}
67
68static res_state
69res_check_reload(res_state statp)
70{
71	struct timespec now;
72	struct stat sb;
73	struct __res_state_ext *ext;
74
75	if ((statp->options & RES_INIT) == 0) {
76		return (statp);
77	}
78
79	ext = statp->_u._ext.ext;
80	if (ext == NULL || ext->reload_period == 0) {
81		return (statp);
82	}
83
84	if (clock_gettime(CLOCK_MONOTONIC_FAST, &now) != 0 ||
85	    (now.tv_sec - ext->conf_stat) < ext->reload_period) {
86		return (statp);
87	}
88
89	ext->conf_stat = now.tv_sec;
90	if (stat(_PATH_RESCONF, &sb) == 0 &&
91	    (sb.st_mtim.tv_sec  != ext->conf_mtim.tv_sec ||
92	     sb.st_mtim.tv_nsec != ext->conf_mtim.tv_nsec)) {
93		statp->options &= ~RES_INIT;
94	}
95
96	return (statp);
97}
98
99res_state
100__res_state(void)
101{
102	res_state statp;
103
104	if (thr_main() != 0)
105		return res_check_reload(&_res);
106
107	if (thr_once(&res_init_once, res_keycreate) != 0 ||
108	    !res_thr_keycreated)
109		return (&_res);
110
111	statp = thr_getspecific(res_key);
112	if (statp != NULL)
113		return res_check_reload(statp);
114	statp = calloc(1, sizeof(*statp));
115	if (statp == NULL)
116		return (&_res);
117#ifdef __BIND_RES_TEXT
118	statp->options = RES_TIMEOUT;			/* Motorola, et al. */
119#endif
120	if (thr_setspecific(res_key, statp) == 0)
121		return (statp);
122	free(statp);
123	return (&_res);
124}
125