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
55struct __res_state _nres
56# if defined(__BIND_RES_TEXT)
57	= { .retrans = RES_TIMEOUT, }	/*%< Motorola, et al. */
58# endif
59	;
60
61static SLIST_HEAD(, _res_st) res_list = LIST_HEAD_INITIALIZER(&res_list);
62
63struct _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
70static pthread_mutex_t res_mtx = PTHREAD_MUTEX_INITIALIZER;
71
72res_state __res_state(void);
73res_state __res_get_state(void);
74void __res_put_state(res_state);
75
76#ifdef RES_STATE_DEBUG
77static void
78res_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
91res_state
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
124void
125/*ARGSUSED*/
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 */
141res_state
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