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/*
* 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: @(#)res_search.c 6.45 (Berkeley) 2/24/91";*/
static char *rcsid = "$Id$";
#endif /* LIBC_SCCS and not lint */
#include <pthread.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <resolv.h>
#include <netdb.h>
#include "res_internal.h"
static char *search_aliases(const char *name, char *buf, int bufsize);
int res_search(const char *name, int class, int type, unsigned char *answer,
int anslen)
{
struct res_data *data;
const char *p;
int num_dots, len, result, no_data = 0, error;
char buf[2 * MAXDNAME + 2], *domain, **dptr, *alias;
data = _res_init();
if (!data)
return -1;
/* Count the dots in name, and get a pointer to the end of name. */
num_dots = 0;
for (p = name; *p; p++) {
if (*p == '.')
num_dots++;
}
len = p - name;
/* If there aren't any dots, check to see if name is an alias for
* another host. If so, try the resolved alias as a fully-qualified
* name. */
alias = search_aliases(name, buf, sizeof(buf));
if (alias != NULL)
return res_query(alias, class, type, answer, anslen);
/* If there's a trailing dot, try to strip it off and query the name. */
if (len > 0 && p[-1] == '.') {
if (len > sizeof(buf)) {
/* It's too long; just query the original name. */
return res_query(name, class, type, answer, anslen);
} else {
/* Copy the name without the trailing dot and query. */
memcpy(buf, name, len - 1);
buf[len] = 0;
return res_query(buf, class, type, answer, anslen);
}
}
if (data->state.options & RES_DNSRCH) {
/* If RES_DNSRCH is set, query all the domains until we get a
* definitive answer. */
for (dptr = data->state.dnsrch; *dptr; dptr++) {
domain = *dptr;
sprintf(buf, "%.*s.%.*s", MAXDNAME, name, MAXDNAME, domain);
result = res_query(buf, class, type, answer, anslen);
if (result > 0)
return result;
if (data->errval == NO_DATA)
no_data = 1;
else if (data->errval != HOST_NOT_FOUND)
break;
}
} else if (num_dots == 0 && data->state.options & RES_DEFNAMES) {
/* If RES_DEFNAMES is set and there is no dot, query the default
* domain. */
domain = data->state.defdname;
sprintf(buf, "%.*s.%.%s", MAXDNAME, name, MAXDNAME, domain);
result = res_query(buf, class, type, answer, anslen);
if (result > 0)
return result;
if (data->errval == NO_DATA)
no_data = 1;
}
/* If all the domain queries failed, try the name as fully-qualified.
* Only do this if there is at least one dot in the name. */
if (num_dots > 0) {
result = res_query(name, class, type, answer, anslen);
if (result > 0)
return result;
}
if (no_data)
data->errval = NO_DATA;
return -1;
}
static char *search_aliases(const char *name, char *buf, int bufsize)
{
FILE *fp;
char *filename, *p;
int len;
filename = getenv("HOSTALIASES");
if (filename == NULL)
return NULL;
fp = fopen(filename, "r");
if (fp == NULL)
return NULL;
len = strlen(name);
while (fgets(buf, bufsize, fp)) {
/* Get the first word from the buffer. */
p = buf;
while (*p && !isspace(*p))
p++;
if (!*p)
break;
/* Null-terminate the first word and compare it with the name. */
*p = 0;
if (strcasecmp(buf, name) != 0)
continue;
p++;
while (isspace(*p))
p++;
fclose(fp);
return (*p) ? p : NULL;
}
fclose(fp);
return NULL;
}
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