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- /*
- * Adopted to Mint-Net 1994, Kay Roemer
- */
-
- /*
- * Copyright (c) 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[] = "@(#)res_query.c 5.11 (Berkeley) 3/6/91";
- #endif /* LIBC_SCCS and not lint */
-
- #include "socklib.h"
- #include <sys/param.h>
- #include <netinet/in.h>
- #include <arpa/inet.h>
- #include <arpa/nameser.h>
- #include <netdb.h>
- #include <resolv.h>
- #include <stdio.h>
- #include <ctype.h>
- #include <errno.h>
- #include <stdlib.h>
- #include <string.h>
-
- #ifdef __MINT__
- #define strcasecmp(a,b) stricmp(a,b)
- #endif
-
- #if PACKETSZ > 1024
- #define MAXPACKET PACKETSZ
- #else
- #define MAXPACKET 1024
- #endif
-
- int h_errno;
-
- /*
- * Formulate a normal query, send, and await answer.
- * Returned answer is placed in supplied buffer "answer".
- * Perform preliminary check of answer, returning success only
- * if no error is indicated and the answer count is nonzero.
- * Return the size of the response on success, -1 on error.
- * Error number is left in h_errno.
- * Caller must parse answer and determine whether it answers the question.
- */
- int
- res_query(name, class, type, answer, anslen)
- const char *name; /* domain name */
- int class, type; /* class and type of query */
- u_char *answer; /* buffer to put answer */
- int anslen; /* size of answer buffer */
- {
- char buf[MAXPACKET];
- HEADER *hp;
- int n;
-
- if ((_res.options & RES_INIT) == 0 && res_init() == -1)
- return (-1);
- #ifdef DEBUG
- if (_res.options & RES_DEBUG)
- printf("res_query(%s, %d, %d)\n", name, class, type);
- #endif
- n = res_mkquery(QUERY, name, class, type, (char *)NULL, 0, NULL,
- buf, sizeof(buf));
-
- if (n <= 0) {
- #ifdef DEBUG
- if (_res.options & RES_DEBUG)
- printf("res_query: mkquery failed\n");
- #endif
- h_errno = NO_RECOVERY;
- return (n);
- }
- n = res_send(buf, n, (char *)answer, anslen);
- if (n < 0) {
- #ifdef DEBUG
- if (_res.options & RES_DEBUG)
- printf("res_query: send error\n");
- #endif
- h_errno = TRY_AGAIN;
- return(n);
- }
-
- hp = (HEADER *) answer;
- if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
- #ifdef DEBUG
- if (_res.options & RES_DEBUG)
- printf("rcode = %d, ancount=%d\n", hp->rcode,
- ntohs(hp->ancount));
- #endif
- switch (hp->rcode) {
- case NXDOMAIN:
- h_errno = HOST_NOT_FOUND;
- break;
- case SERVFAIL:
- h_errno = TRY_AGAIN;
- break;
- case NOERROR:
- h_errno = NO_DATA;
- break;
- case FORMERR:
- case NOTIMP:
- case REFUSED:
- default:
- h_errno = NO_RECOVERY;
- break;
- }
- return (-1);
- }
- return(n);
- }
-
- /*
- * Formulate a normal query, send, and retrieve answer in supplied buffer.
- * Return the size of the response on success, -1 on error.
- * If enabled, implement search rules until answer or unrecoverable failure
- * is detected. Error number is left in h_errno.
- * Only useful for queries in the same name hierarchy as the local host
- * (not, for example, for host address-to-name lookups in domain in-addr.arpa).
- */
- int
- res_search(name, class, type, answer, anslen)
- char *name; /* domain name */
- int class, type; /* class and type of query */
- u_char *answer; /* buffer to put answer */
- int anslen; /* size of answer */
- {
- register char *cp, **domain;
- int n, ret, got_nodata = 0;
- char *__hostalias();
-
- if ((_res.options & RES_INIT) == 0 && res_init() == -1)
- return (-1);
-
- errno = 0;
- h_errno = HOST_NOT_FOUND; /* default, if we never query */
- for (cp = name, n = 0; *cp; cp++)
- if (*cp == '.')
- n++;
- if (n == 0 && (cp = __hostalias(name)))
- return (res_query(cp, class, type, answer, anslen));
-
- /*
- * We do at least one level of search if
- * - there is no dot and RES_DEFNAME is set, or
- * - there is at least one dot, there is no trailing dot,
- * and RES_DNSRCH is set.
- */
- if ((n == 0 && _res.options & RES_DEFNAMES) ||
- (n != 0 && *--cp != '.' && _res.options & RES_DNSRCH))
- for (domain = _res.dnsrch; *domain; domain++) {
- ret = res_querydomain(name, *domain, class, type,
- answer, anslen);
- if (ret > 0)
- return (ret);
- /*
- * If no server present, give up.
- * If name isn't found in this domain,
- * keep trying higher domains in the search list
- * (if that's enabled).
- * On a NO_DATA error, keep trying, otherwise
- * a wildcard entry of another type could keep us
- * from finding this entry higher in the domain.
- * If we get some other error (negative answer or
- * server failure), then stop searching up,
- * but try the input name below in case it's fully-qualified.
- */
- if (errno == ECONNREFUSED) {
- h_errno = TRY_AGAIN;
- return (-1);
- }
- if (h_errno == NO_DATA)
- got_nodata++;
- if ((h_errno != HOST_NOT_FOUND && h_errno != NO_DATA) ||
- (_res.options & RES_DNSRCH) == 0)
- break;
- }
- /*
- * If the search/default failed, try the name as fully-qualified,
- * but only if it contained at least one dot (even trailing).
- * This is purely a heuristic; we assume that any reasonable query
- * about a top-level domain (for servers, SOA, etc) will not use
- * res_search.
- */
- if (n && (ret = res_querydomain(name, (char *)NULL, class, type,
- answer, anslen)) > 0)
- return (ret);
- if (got_nodata)
- h_errno = NO_DATA;
- return (-1);
- }
-
- /*
- * Perform a call on res_query on the concatenation of name and domain,
- * removing a trailing dot from name if domain is NULL.
- */
- int
- res_querydomain(name, domain, class, type, answer, anslen)
- char *name, *domain;
- int class, type; /* class and type of query */
- u_char *answer; /* buffer to put answer */
- int anslen; /* size of answer */
- {
- char nbuf[2*MAXDNAME+2];
- char *longname = nbuf;
- int n;
-
- #ifdef DEBUG
- if (_res.options & RES_DEBUG)
- printf("res_querydomain(%s, %s, %d, %d)\n",
- name, domain, class, type);
- #endif
- if (domain == NULL) {
- /*
- * Check for trailing '.';
- * copy without '.' if present.
- */
- n = strlen(name) - 1;
- if (name[n] == '.' && n < sizeof(nbuf) - 1) {
- bcopy(name, nbuf, n);
- nbuf[n] = '\0';
- } else
- longname = name;
- } else
- (void)sprintf(nbuf, "%.*s.%.*s",
- MAXDNAME, name, MAXDNAME, domain);
-
- return (res_query(longname, class, type, answer, anslen));
- }
-
- char *
- __hostalias(name)
- register const char *name;
- {
- register char *C1, *C2;
- FILE *fp;
- char *file, *getenv(), *strcpy(), *strncpy();
- char buf[BUFSIZ];
- static char abuf[MAXDNAME];
- extern int strcasecmp (const char *, const char *);
-
- file = getenv("HOSTALIASES");
- if (file == NULL || (fp = fopen(file, "rt")) == NULL)
- return (NULL);
- buf[sizeof(buf) - 1] = '\0';
- while (fgets(buf, sizeof(buf), fp)) {
- for (C1 = buf; *C1 && !isspace(*C1); ++C1);
- if (!*C1)
- break;
- *C1 = '\0';
- if (!strcasecmp(buf, name)) {
- while (isspace(*++C1));
- if (!*C1)
- break;
- for (C2 = C1 + 1; *C2 && !isspace(*C2); ++C2);
- abuf[sizeof(abuf) - 1] = *C2 = '\0';
- (void)strncpy(abuf, C1, sizeof(abuf) - 1);
- fclose(fp);
- return (abuf);
- }
- }
- fclose(fp);
- return (NULL);
- }
-