1 /* $NetBSD: res_state.c,v 1.6 2008/04/28 20:23:02 martin Exp $ */
2
3 /*-
4 * Copyright (c) 2004 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Christos Zoulas.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 /* Note to Haiku Developers:
33 -------------------------
34 This file contains the thread-safe versions of res functions, taken from
35 NetBSD's libpthread directory. Do *not* replace it with the legacy
36 single-threaded version from NetBSD's netresolv directory.
37 */
38
39 #include <sys/cdefs.h>
40 #if defined(LIBC_SCCS) && !defined(lint)
41 __RCSID("$NetBSD: res_state.c,v 1.6 2008/04/28 20:23:02 martin Exp $");
42 #endif
43
44 #include <sys/types.h>
45 #include <sys/queue.h>
46 #include <arpa/inet.h>
47 #include <arpa/nameser.h>
48 #include <stdlib.h>
49 #include <unistd.h>
50 #include <resolv.h>
51 #include <netdb.h>
52
53 #include <pthread.h>
54
55 struct __res_state _nres
56 # if defined(__BIND_RES_TEXT)
57 = { .retrans = RES_TIMEOUT, } /*%< Motorola, et al. */
58 # endif
59 ;
60
61 static SLIST_HEAD(, _res_st) res_list = LIST_HEAD_INITIALIZER(&res_list);
62
63 struct _res_st {
64 /* __res_put_state() assumes st_res is the first member. */
65 struct __res_state st_res;
66
67 SLIST_ENTRY(_res_st) st_list;
68 };
69
70 static pthread_mutex_t res_mtx = PTHREAD_MUTEX_INITIALIZER;
71
72 res_state __res_state(void);
73 res_state __res_get_state(void);
74 void __res_put_state(res_state);
75
76 #ifdef RES_STATE_DEBUG
77 static void
res_state_debug(const char * msg,void * p)78 res_state_debug(const char *msg, void *p)
79 {
80 char buf[512];
81 pthread_t self = pthread__self();
82 int len = snprintf(buf, sizeof(buf), "%p: %s %p\n", self, msg, p);
83
84 (void)write(STDOUT_FILENO, buf, (size_t)len);
85 }
86 #else
87 #define res_state_debug(a, b)
88 #endif
89
90
91 res_state
__res_get_state(void)92 __res_get_state(void)
93 {
94 res_state res;
95 struct _res_st *st;
96 pthread_mutex_lock(&res_mtx);
97 st = SLIST_FIRST(&res_list);
98 if (st != NULL) {
99 SLIST_REMOVE_HEAD(&res_list, st_list);
100 pthread_mutex_unlock(&res_mtx);
101 res = &st->st_res;
102 res_state_debug("checkout from list", st);
103 } else {
104 pthread_mutex_unlock(&res_mtx);
105 st = malloc(sizeof(*st));
106 if (st == NULL) {
107 h_errno = NETDB_INTERNAL;
108 return NULL;
109 }
110 res = &st->st_res;
111 res->options = 0;
112 res_state_debug("alloc new", res);
113 }
114 if ((res->options & RES_INIT) == 0) {
115 if (res_ninit(res) == -1) {
116 h_errno = NETDB_INTERNAL;
117 free(st);
118 return NULL;
119 }
120 }
121 return res;
122 }
123
124 void
125 /*ARGSUSED*/
__res_put_state(res_state res)126 __res_put_state(res_state res)
127 {
128 struct _res_st *st = (struct _res_st *)(void *)res;
129
130 res_state_debug("free", res);
131 pthread_mutex_lock(&res_mtx);
132 SLIST_INSERT_HEAD(&res_list, st, st_list);
133 pthread_mutex_unlock(&res_mtx);
134 }
135
136
137 /*
138 * This is aliased via a macro to _res.
139 * This function is not thread safe.
140 */
141 res_state
__res_state(void)142 __res_state(void)
143 {
144 if ((_nres.options & RES_INIT) == 0 && res_ninit(&_nres) == -1) {
145 h_errno = NETDB_INTERNAL;
146 return NULL;
147 }
148
149 return &_nres;
150 }
151