xref: /freebsd/lib/libc/resolv/res_state.c (revision 7ef62cebc2f965b0f640263e179276928885e33d)
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  * $FreeBSD$
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 
46 struct __res_state _res;
47 
48 static thread_key_t res_key;
49 static once_t res_init_once = ONCE_INITIALIZER;
50 static int res_thr_keycreated = 0;
51 
52 static void
53 free_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 
62 static void
63 res_keycreate(void)
64 {
65 	res_thr_keycreated = thr_keycreate(&res_key, free_res) == 0;
66 }
67 
68 static res_state
69 res_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 
99 res_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