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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /resolv/res_query.c
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initial import
Diffstat (limited to 'resolv/res_query.c')
-rw-r--r--resolv/res_query.c384
1 files changed, 384 insertions, 0 deletions
diff --git a/resolv/res_query.c b/resolv/res_query.c
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+/*
+ * ++Copyright++ 1988, 1993
+ * -
+ * Copyright (c) 1988, 1993
+ * The 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.
+ * -
+ * Portions Copyright (c) 1993 by Digital Equipment Corporation.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies, and that
+ * the name of Digital Equipment Corporation not be used in advertising or
+ * publicity pertaining to distribution of the document or software without
+ * specific, written prior permission.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
+ * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
+ * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+ * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+ * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
+ * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
+ * SOFTWARE.
+ * -
+ * --Copyright--
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+static char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
+static char rcsid[] = "$Id$";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/param.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <arpa/nameser.h>
+
+#include <stdio.h>
+#include <netdb.h>
+#include <resolv.h>
+#include <ctype.h>
+#include <errno.h>
+#if defined(BSD) && (BSD >= 199306)
+# include <stdlib.h>
+# include <string.h>
+#else
+# include "../conf/portability.h"
+#endif
+
+#if defined(USE_OPTIONS_H)
+# include <../conf/options.h>
+#endif
+
+#if PACKETSZ > 1024
+#define MAXPACKET PACKETSZ
+#else
+#define MAXPACKET 1024
+#endif
+
+char *__hostalias __P((const char *));
+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 */
+{
+ u_char buf[MAXPACKET];
+ register HEADER *hp = (HEADER *) answer;
+ int n;
+
+ hp->rcode = NOERROR; /* default */
+
+ if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
+ h_errno = NETDB_INTERNAL;
+ 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, 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, 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);
+ }
+
+ 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 code, if any, is left in h_errno.
+ */
+int
+res_search(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 */
+{
+ register const char *cp, * const *domain;
+ HEADER *hp = (HEADER *) answer;
+ u_int dots;
+ int trailing_dot, ret, saved_herrno;
+ int got_nodata = 0, got_servfail = 0, tried_as_is = 0;
+
+ if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
+ h_errno = NETDB_INTERNAL;
+ return (-1);
+ }
+ errno = 0;
+ h_errno = HOST_NOT_FOUND; /* default, if we never query */
+ dots = 0;
+ for (cp = name; *cp; cp++)
+ dots += (*cp == '.');
+ trailing_dot = 0;
+ if (cp > name && *--cp == '.')
+ trailing_dot++;
+
+ /*
+ * if there aren't any dots, it could be a user-level alias
+ */
+ if (!dots && (cp = __hostalias(name)) != NULL)
+ return (res_query(cp, class, type, answer, anslen));
+
+ /*
+ * If there are dots in the name already, let's just give it a try
+ * 'as is'. The threshold can be set with the "ndots" option.
+ */
+ saved_herrno = -1;
+ if (dots >= _res.ndots) {
+ ret = res_querydomain(name, NULL, class, type, answer, anslen);
+ if (ret > 0)
+ return (ret);
+ saved_herrno = h_errno;
+ tried_as_is++;
+ }
+
+ /*
+ * 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 ((!dots && (_res.options & RES_DEFNAMES)) ||
+ (dots && !trailing_dot && (_res.options & RES_DNSRCH))) {
+ int done = 0;
+
+ for (domain = (const char * const *)_res.dnsrch;
+ *domain && !done;
+ 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);
+ }
+
+ switch (h_errno) {
+ case NO_DATA:
+ got_nodata++;
+ /* FALLTHROUGH */
+ case HOST_NOT_FOUND:
+ /* keep trying */
+ break;
+ case TRY_AGAIN:
+ if (hp->rcode == SERVFAIL) {
+ /* try next search element, if any */
+ got_servfail++;
+ break;
+ }
+ /* FALLTHROUGH */
+ default:
+ /* anything else implies that we're done */
+ done++;
+ }
+
+ /* if we got here for some reason other than DNSRCH,
+ * we only wanted one iteration of the loop, so stop.
+ */
+ if (!(_res.options & RES_DNSRCH))
+ done++;
+ }
+ }
+
+ /* if we have not already tried the name "as is", do that now.
+ * note that we do this regardless of how many dots were in the
+ * name or whether it ends with a dot.
+ */
+ if (!tried_as_is) {
+ ret = res_querydomain(name, NULL, class, type, answer, anslen);
+ if (ret > 0)
+ return (ret);
+ }
+
+ /* if we got here, we didn't satisfy the search.
+ * if we did an initial full query, return that query's h_errno
+ * (note that we wouldn't be here if that query had succeeded).
+ * else if we ever got a nodata, send that back as the reason.
+ * else send back meaningless h_errno, that being the one from
+ * the last DNSRCH we did.
+ */
+ if (saved_herrno != -1)
+ h_errno = saved_herrno;
+ else if (got_nodata)
+ h_errno = NO_DATA;
+ else if (got_servfail)
+ h_errno = TRY_AGAIN;
+ 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)
+ const 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];
+ const char *longname = nbuf;
+ int n;
+
+#ifdef DEBUG
+ if (_res.options & RES_DEBUG)
+ printf(";; res_querydomain(%s, %s, %d, %d)\n",
+ name, domain?domain:"<Nil>", class, type);
+#endif
+ if (domain == NULL) {
+ /*
+ * Check for trailing '.';
+ * copy without '.' if present.
+ */
+ n = strlen(name) - 1;
+ if (n != (0 - 1) && name[n] == '.' && n < sizeof(nbuf) - 1) {
+ bcopy(name, nbuf, n);
+ nbuf[n] = '\0';
+ } else
+ longname = name;
+ } else
+ 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 *cp1, *cp2;
+ FILE *fp;
+ char *file;
+ char buf[BUFSIZ];
+ static char abuf[MAXDNAME];
+
+ file = getenv("HOSTALIASES");
+ if (file == NULL || (fp = fopen(file, "r")) == NULL)
+ return (NULL);
+ buf[sizeof(buf) - 1] = '\0';
+ while (fgets(buf, sizeof(buf), fp)) {
+ for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1)
+ ;
+ if (!*cp1)
+ break;
+ *cp1 = '\0';
+ if (!strcasecmp(buf, name)) {
+ while (isspace(*++cp1))
+ ;
+ if (!*cp1)
+ break;
+ for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)
+ ;
+ abuf[sizeof(abuf) - 1] = *cp2 = '\0';
+ strncpy(abuf, cp1, sizeof(abuf) - 1);
+ fclose(fp);
+ return (abuf);
+ }
+ }
+ fclose(fp);
+ return (NULL);
+}