140 lines
3.8 KiB
C
140 lines
3.8 KiB
C
/* $NetBSD: res_state.c,v 1.7 2022/02/12 14:59:32 riastradh Exp $ */
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/*-
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* Copyright (c) 2004 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Christos Zoulas.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#if defined(LIBC_SCCS) && !defined(lint)
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__RCSID("$NetBSD: res_state.c,v 1.7 2022/02/12 14:59:32 riastradh Exp $");
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#endif
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/* Need to use libc-private names for atomic operations. */
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#include "../../common/lib/libc/atomic/atomic_op_namespace.h"
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#include <sys/types.h>
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#include <sys/queue.h>
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#include <arpa/inet.h>
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#include <arpa/nameser.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <resolv.h>
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#include <netdb.h>
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#include "pthread.h"
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#include "pthread_int.h"
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static SLIST_HEAD(, _res_st) res_list = LIST_HEAD_INITIALIZER(&res_list);
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struct _res_st {
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/* __res_put_state() assumes st_res is the first member. */
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struct __res_state st_res;
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SLIST_ENTRY(_res_st) st_list;
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};
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static pthread_mutex_t res_mtx = PTHREAD_MUTEX_INITIALIZER;
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res_state __res_state(void);
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res_state __res_get_state(void);
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void __res_put_state(res_state);
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#ifdef RES_STATE_DEBUG
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static void
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res_state_debug(const char *msg, void *p)
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{
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char buf[512];
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pthread_t self = pthread__self();
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int len = snprintf(buf, sizeof(buf), "%p: %s %p\n", self, msg, p);
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(void)write(STDOUT_FILENO, buf, (size_t)len);
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}
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#else
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#define res_state_debug(a, b)
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#endif
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res_state
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__res_get_state(void)
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{
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res_state res;
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struct _res_st *st;
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pthread_mutex_lock(&res_mtx);
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st = SLIST_FIRST(&res_list);
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if (st != NULL) {
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SLIST_REMOVE_HEAD(&res_list, st_list);
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pthread_mutex_unlock(&res_mtx);
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res = &st->st_res;
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res_state_debug("checkout from list", st);
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} else {
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pthread_mutex_unlock(&res_mtx);
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st = malloc(sizeof(*st));
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if (st == NULL) {
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h_errno = NETDB_INTERNAL;
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return NULL;
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}
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res = &st->st_res;
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res->options = 0;
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res_state_debug("alloc new", res);
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}
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if ((res->options & RES_INIT) == 0) {
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if (res_ninit(res) == -1) {
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h_errno = NETDB_INTERNAL;
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free(st);
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return NULL;
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}
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}
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return res;
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}
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void
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/*ARGSUSED*/
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__res_put_state(res_state res)
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{
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struct _res_st *st = (struct _res_st *)(void *)res;
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res_state_debug("free", res);
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pthread_mutex_lock(&res_mtx);
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SLIST_INSERT_HEAD(&res_list, st, st_list);
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pthread_mutex_unlock(&res_mtx);
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}
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/*
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* This is aliased via a macro to _res; don't allow multi-threaded programs
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* to use it.
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*/
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res_state
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__res_state(void)
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{
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static const char res[] = "_res is not supported for multi-threaded"
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" programs.\n";
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(void)write(STDERR_FILENO, res, sizeof(res) - 1);
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abort();
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return NULL;
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}
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