1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
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
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
44 struct __res_state _res;
45
46 static thread_key_t res_key;
47 static once_t res_init_once = ONCE_INITIALIZER;
48 static int res_thr_keycreated = 0;
49
50 static void
free_res(void * ptr)51 free_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
60 static void
res_keycreate(void)61 res_keycreate(void)
62 {
63 res_thr_keycreated = thr_keycreate(&res_key, free_res) == 0;
64 }
65
66 static res_state
res_check_reload(res_state statp)67 res_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
97 res_state
__res_state(void)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