gethostbyaddr.c
上传用户:tsgydb
上传日期:2007-04-14
资源大小:10674k
文件大小:5k
- /*
- * Copyright (c) 1985, 1988 Regents of the University of California.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- * must display the following acknowledgement:
- * This product includes software developed by the University of
- * California, Berkeley and its contributors.
- * 4. Neither the name of the University nor the names of its contributors
- * may be used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
- #if defined(LIBC_SCCS) && !defined(lint)
- /*static char *sccsid = "from: @(#)gethostbyaddr.c 6.45 (Berkeley) 2/24/91";*/
- static char *rcsid = "$Id$";
- #endif /* LIBC_SCCS and not lint */
- #include <pthread.h>
- #include <stdio.h>
- #include <string.h>
- #include <stdlib.h>
- #include <netdb.h>
- #include <netinet/in.h>
- #include <resolv.h>
- #include <netinet/in.h>
- #include <errno.h>
- #include <sys/socket.h>
- #include "res_internal.h"
- static struct hostent *file_find_addr(const char *addr, int len, int type,
- struct hostent *result, char *buf,
- int bufsize, int *errval);
- struct hostent *gethostbyaddr(const char *addr, int len, int type)
- {
- struct res_data *data = _res_init();
- if (!data)
- return NULL;
- if (!data->buf) {
- data->buf = malloc(sizeof(struct hostent) + HOST_BUFSIZE);
- if (!data->buf) {
- errno = 0;
- data->errval = NO_RECOVERY;
- return NULL;
- }
- }
- return gethostbyaddr_r(addr, len, type, (struct hostent *) data->buf,
- data->buf + sizeof(struct hostent), HOST_BUFSIZE,
- &data->errval);
- }
- struct hostent *gethostbyaddr_r(const char *addr, int len, int type,
- struct hostent *result, char *buf, int bufsize,
- int *errval)
- {
- struct res_data *data;
- querybuf qbuf;
- char lookups[MAXDNSLUS], addrbuf[MAXDNAME], *abuf;
- struct hostent *hp;
- int n, i;
- /* Default failure condition is not a range error and not recoverable. */
- errno = 0;
- *errval = NO_RECOVERY;
-
- data = _res_init();
- if (!data)
- return NULL;
- if (type != AF_INET)
- return NULL;
- sprintf(addrbuf, "%u.%u.%u.%u.in-addr.arpa",
- (unsigned)addr[3] & 0xff, (unsigned)addr[2] & 0xff,
- (unsigned)addr[1] & 0xff, (unsigned)addr[0] & 0xff);
- memcpy(lookups, data->state.lookups, sizeof(lookups));
- if (*lookups == 0)
- strncpy(lookups, "bf", sizeof(lookups));
- hp = NULL;
- for (i = 0; i < MAXDNSLUS && hp == NULL && lookups[i]; i++) {
- switch (lookups[i]) {
- case 'b':
- /* Allocate space for a one-item list of addresses. */
- abuf = SP(SP(buf, char *, 2), struct in_addr, 1);
- if (abuf > buf + bufsize) {
- errno = ERANGE;
- return NULL;
- }
- /* Perform and parse the query. */
- n = res_query(addrbuf, C_IN, T_PTR, (char *)&qbuf, sizeof(qbuf));
- if (n < 0)
- break;
- hp = _res_parse_answer(&qbuf, n, 1, result, abuf,
- bufsize - (abuf - buf), errval);
- if (hp == NULL)
- break;
- /* Fill in our own address list. */
- result->h_addrtype = type;
- result->h_length = len;
- result->h_addr_list = (char **) ALIGN(buf, char *);
- result->h_addr_list[0] = ALIGN(&result->h_addr_list[2],
- struct in_addr);
- result->h_addr_list[1] = NULL;
- break;
- case 'f':
- hp = file_find_addr(addr, len, type, result, buf, bufsize, errval);
- break;
- }
- }
- return hp;
- }
- static struct hostent *file_find_addr(const char *addr, int len, int type,
- struct hostent *result, char *buf,
- int bufsize, int *errval)
- {
- FILE *fp = NULL;
- pthread_mutex_lock(&host_iterate_lock);
- sethostent(0);
- while ((result = gethostent_r(result, buf, bufsize, errval)) != NULL) {
- /* Check the entry against the given address. */
- if (result->h_addrtype == type &&
- memcmp(result->h_addr, addr, len) == 0)
- break;
- }
- pthread_mutex_unlock(&host_iterate_lock);
- if (!result && errno != ERANGE)
- *errval = HOST_NOT_FOUND;
- return result;
- }