res_send.c

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/*
 * ++Copyright++ 1985, 1989, 1993
 * -
 * Copyright (c) 1985, 1989, 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_send.c	8.1 (Berkeley) 6/4/93";
static char rcsid[] = "$Id: res_send.c,v 1.2 1994/07/28 21:56:28 roland Exp $";
#endif /* LIBC_SCCS and not lint */

	/* change this to "0"
	 * if you talk to a lot
	 * of multi-homed SunOS
	 * ("broken") name servers.
	 */
#define	CHECK_SRVR_ADDR	1	/* XXX - should be in options.h */

/*
 * Send query to name server and wait for reply.
 */

#include <sys/param.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <arpa/inet.h>

#include <stdio.h>
#include <errno.h>
#include <resolv.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

void _res_close __P((void));

static int s = -1;	/* socket used for communications */
static int connected = 0;	/* is the socket connected */
static int vc = 0;	/* is the socket a virtual ciruit? */

#ifndef FD_SET
/* XXX - should be in portability.h */
#define	NFDBITS		32
#define	FD_SETSIZE	32
#define	FD_SET(n, p)	((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
#define	FD_CLR(n, p)	((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
#define	FD_ISSET(n, p)	((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
#define FD_ZERO(p)	bzero((char *)(p), sizeof(*(p)))
#endif

#ifndef DEBUG
#   define Dprint(cond, args) /*empty*/
#   define DprintQ(cond, args, query) /*empty*/
#   define Aerror(file, string, error, address) /*empty*/
#   define Perror(file, string, error) /*empty*/
#else
#   define Dprint(cond, args) if (cond) {fprintf args;} else {}
#   define DprintQ(cond, args, query) if (cond) {\
			fprintf args;\
			__p_query(query);\
		} else {}
    static void
    Aerror(file, string, error, address)
	FILE *file;
	char *string;
	int error;
	struct sockaddr_in address;
    {
	int save = errno;

	if (_res.options & RES_DEBUG) {
		fprintf(file, "res_send: %s ([%s].%d): %s\n",
			string,
			inet_ntoa(address.sin_addr),
			address.sin_port,
			strerror(error));
	}
	errno = save;
    }
    static void
    Perror(file, string, error)
	FILE *file;
	char *string;
	int error;
    {
	int save = errno;

	if (_res.options & RES_DEBUG) {
		fprintf(file, "res_send: %s: %s\n",
			string, strerror(error));
	}
	errno = save;
    }
#endif

static res_send_qhook Qhook = NULL;
static res_send_rhook Rhook = NULL;

void
res_send_setqhook(hook)
	res_send_qhook hook;
{
	Qhook = hook;
}

void
res_send_setrhook(hook)
	res_send_rhook hook;
{
	Rhook = hook;
}

/* int
 * our_server(ina)
 *	looks up "ina" in _res.ns_addr_list[]
 * returns:
 *	0  : not found
 *	>0 : found
 * author:
 *	paul vixie, 29may94
 */
static int
our_server(inp)
	const struct sockaddr_in *inp;
{
	struct sockaddr_in ina;
	register int ns, ret;

	ina = *inp;
	ret = 0;
	for (ns = 0;  ns < _res.nscount;  ns++) {
		register const struct sockaddr_in *srv = &_res.nsaddr_list[ns];

		if (srv->sin_family == ina.sin_family &&
		    srv->sin_port == ina.sin_port &&
		    (srv->sin_addr.s_addr == INADDR_ANY ||
		     srv->sin_addr.s_addr == ina.sin_addr.s_addr)) {
			ret++;
			break;
		}
	}
	return (ret);
}

/* int
 * name_in_query(name, type, class, buf, eom)
 *	look for (name,type,class) in the query section of packet (buf,eom)
 * returns:
 *	-1 : format error
 *	0  : not found
 *	>0 : found
 */
static int
name_in_query(name, type, class, buf, eom)
	const char *name;
	register int type, class;
	const u_char *buf, *eom;
{
	register const u_char *cp = buf + HFIXEDSZ;
	int qdcount = ntohs(((HEADER*)buf)->qdcount);

	while (qdcount-- > 0) {
		char tname[MAXDNAME+1];
		register int n, ttype, tclass;

		n = dn_expand(buf, eom, cp, tname, sizeof tname);
		if (n < 0)
			return (-1);
		cp += n;
		ttype = _getshort(cp);	cp += INT16SZ;
		tclass = _getshort(cp); cp += INT16SZ;
		if (ttype == type &&
		    tclass == class &&
		    strcasecmp(tname, name) == 0)
			return (1);
	}
	return (0);
}

/* int
 * queries_match(buf1, eom1, buf2, eom2)
 *	is there a 1:1 mapping of (name,type,class)
 *	in (buf1,eom1) and (buf2,eom2)?
 * returns:
 *	-1 : format error
 *	0  : not a 1:1 mapping
 *	>0 : is a 1:1 mapping
 */
static int
queries_match(buf1, eom1, buf2, eom2)
	const u_char *buf1, *eom1;
	const u_char *buf2, *eom2;
{
	register const u_char *cp = buf1 + HFIXEDSZ;
	int qdcount = ntohs(((HEADER*)buf1)->qdcount);

	if (qdcount != ntohs(((HEADER*)buf2)->qdcount))
		return (0);
	while (qdcount-- > 0) {
		char tname[MAXDNAME+1];
		register int n, ttype, tclass;

		n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
		if (n < 0)
			return (-1);
		cp += n;
		ttype = _getshort(cp);	cp += INT16SZ;
		tclass = _getshort(cp); cp += INT16SZ;
		if (!name_in_query(tname, ttype, tclass, buf2, eom2))
			return (0);
	}
	return (1);
}

int
res_send(buf, buflen, ans, anssiz)
	const u_char	*buf;
	int		buflen;
	u_char		*ans;
	int		anssiz;
{
	HEADER		*hp = (HEADER *) buf;
	HEADER		*anhp = (HEADER *) ans;
	int		gotsomewhere = 0,
			connreset = 0,
			terrno = ETIMEDOUT;

	register int	n;
	int		try, v_circuit, resplen, ns;
	u_int		badns;	/* XXX NSMAX can't exceed #/bits in this var */

	DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_QUERY),
		(stdout, ";; res_send()\n"), buf);
	if (!(_res.options & RES_INIT)) {
		if (res_init() == -1)
			return (-1);
	}
	v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ;
	badns = 0;

	/*
	 * Send request, RETRY times, or until successful
	 */
	for (try = 0; try < _res.retry; try++) {
	    for (ns = 0; ns < _res.nscount; ns++) {
		struct sockaddr_in *nsap = &_res.nsaddr_list[ns];
    same_ns:
		if (badns & (1<<ns)) {
			_res_close();
			goto next_ns;
		}

		if (Qhook) {
			int done = 0, loops = 0;

			do {
				res_sendhookact act;

				act = (*Qhook)(&nsap,
					       &buf,
					       &buflen,
					       ans,
					       anssiz,
					       &resplen);
				switch (act) {
				case res_goahead:
					done = 1;
					break;
				case res_nextns:
					_res_close();
					goto next_ns;
				case res_done:
					return (resplen);
				case res_modified:
					/* give the hook another try */
					if (++loops < 42) /*doug adams*/
						break;
					/*FALLTHROUGH*/
				case res_error:
					/*FALLTHROUGH*/
				default:
					return (-1);
				}
			} while (!done);
		}

		Dprint(_res.options & RES_DEBUG,
		       (stdout, ";; Querying server (# %d) address = %s\n",
			ns+1, inet_ntoa(nsap->sin_addr)));

		if (v_circuit) {
			int		truncated;
			struct iovec	iov[2];
			u_short		len;
			u_char		*cp;

			/*
			 * Use virtual circuit;
			 * at most one attempt per server.
			 */
			try = _res.retry;
			truncated = 0;
			if ((s < 0) || (!vc)) {
				if (s >= 0)
					_res_close();

				s = socket(AF_INET, SOCK_STREAM, PF_UNSPEC);
				if (s < 0) {
					terrno = errno;
					Perror(stderr, "socket(vc)", errno);
					return (-1);
				}
				if (connect(s,
					    (struct sockaddr *)nsap,
					    sizeof(struct sockaddr))
				    < 0) {
					terrno = errno;
					Aerror(stderr, "connect/vc",
					       errno, *nsap);
					badns |= (1<<ns);