res_send.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

/*
 * 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.
 */

/*
 * Portions Copyright (c) 1996 by Internet Software Consortium.
 *
 * 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)res_send.c	8.1 (Berkeley) 6/4/93";
static char orig_rcsid[] = "From: Id: res_send.c,v 8.20 1998/04/06 23:27:51 halley Exp $";
static char rcsid[] = "$Id: res_send.c,v 1.5 2002/07/24 13:25:06 joel Exp $";
#endif /* LIBC_SCCS and not lint */

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

#include <sys/types.h>
#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 <errno.h>
#include <netdb.h>
#include <resolv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#if !defined(__rtems__)
#include <poll.h>
#endif

#include "res_config.h"

#if !defined(__rtems__)

#ifdef NOPOLL			/* libc_r doesn't wrap poll yet() */
static int use_poll = 0;
#else
static int use_poll = 1;	/* adapt to poll() syscall availability */
				/* 0 = not present, 1 = try it, 2 = exists */
#endif
#endif

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 circuit? */
static res_send_qhook Qhook = NULL;
static res_send_rhook Rhook = NULL;


#define CAN_RECONNECT 1

#ifndef DEBUG
#   define Dprint(cond, args) /*empty*/
#   define DprintQ(cond, args, query, size) /*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, size) if (cond) {\
			fprintf args;\
			__fp_nquery(query, size, stdout);\
		} 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].%u): %s\n",
			string,
			inet_ntoa(address.sin_addr),
			ntohs(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

void
res_send_setqhook(hook)
	res_send_qhook hook;
{

	Qhook = hook;
}

void
res_send_setrhook(hook)
	res_send_rhook hook;
{

	Rhook = hook;
}

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

	ina = *inp;
	ret = 0;
	for (ns = 0;  ns < _res.nscount;  ns++) {
		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
 * res_nameinquery(name, type, class, buf, eom)
 *	look for (name,type,class) in the query section of packet (buf,eom)
 * requires:
 *	buf + HFIXEDSZ <= eom
 * returns:
 *	-1 : format error
 *	0  : not found
 *	>0 : found
 * author:
 *	paul vixie, 29may94
 */
int
res_nameinquery(name, type, class, buf, eom)
	const char *name;
	int type, class;
	const u_char *buf, *eom;
{
	const u_char *cp = buf + HFIXEDSZ;
	int qdcount = ntohs(((HEADER*)buf)->qdcount);

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

		n = dn_expand(buf, eom, cp, tname, sizeof tname);
		if (n < 0)
			return (-1);
		cp += n;
		if (cp + 2 * INT16SZ > eom)
			return (-1);
		ttype = ns_get16(cp); cp += INT16SZ;
		tclass = ns_get16(cp); cp += INT16SZ;
		if (ttype == type &&
		    tclass == class &&
		    strcasecmp(tname, name) == 0)
			return (1);
	}
	return (0);
}

/* int
 * res_queriesmatch(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
 * author:
 *	paul vixie, 29may94
 */
int
res_queriesmatch(buf1, eom1, buf2, eom2)
	const u_char *buf1, *eom1;
	const u_char *buf2, *eom2;
{
	const u_char *cp = buf1 + HFIXEDSZ;
	int qdcount = ntohs(((HEADER*)buf1)->qdcount);

	if (buf1 + HFIXEDSZ > eom1 || buf2 + HFIXEDSZ > eom2)
		return (-1);

	/*
	 * Only header section present in replies to
	 * dynamic update packets.
	 */
	if ( (((HEADER *)buf1)->opcode == ns_o_update) &&
	     (((HEADER *)buf2)->opcode == ns_o_update) )
		return (1);

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

		n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
		if (n < 0)
			return (-1);
		cp += n;
		if (cp + 2 * INT16SZ > eom1)
			return (-1);
		ttype = ns_get16(cp);	cp += INT16SZ;
		tclass = ns_get16(cp); cp += INT16SZ;
		if (!res_nameinquery(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, connreset, terrno, try, v_circuit, resplen, ns, n;
	u_int badns;	/* XXX NSMAX can't exceed #/bits in this variable */

	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
		/* errno should have been set by res_init() in this case. */
		return (-1);
	}
	if (anssiz < HFIXEDSZ) {
		errno = EINVAL;
		return (-1);
	}
	DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_QUERY),
		(stdout, ";; res_send()\n"), buf, buflen);
	v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ;
	gotsomewhere = 0;
	connreset = 0;
	terrno = ETIMEDOUT;
	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;
#if !defined(__rtems__)
			struct iovec iov[2];
#endif
			u_short len;
			u_char *cp;

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

				s = socket(PF_INET, SOCK_STREAM, 0);
				if (s < 0) {
					terrno = errno;
					Perror(stderr, "socket(vc)", errno);
					return (-1);
				}
				errno = 0;
				if (connect(s, (struct sockaddr *)nsap,
					    sizeof *nsap) < 0) {
					terrno = errno;
					Aerror(stderr, "connect/vc",
					       errno, *nsap);
					badns |= (1 << ns);
					res_close();
					goto next_ns;
				}
				vc = 1;
			}
			/*
			 * Send length & message
			 */
			putshort((u_short)buflen, (u_char*)&len);
#if !defined(__rtems__)
			iov[0].iov_base = (caddr_t)&len;
			iov[0].iov_len = INT16SZ;
			iov[1].iov_base = (caddr_t)buf;
			iov[1].iov_len = buflen;
			if (writev(s, iov, 2) != (INT16SZ + buflen)) {
#else
			/*
			 * RTEMS doesn't have writev (yet)
			 */
			if ((write (s, &len, INT16SZ) != INT16SZ)
			 || (write (s, buf, buflen) != buflen)) {
#endif
				terrno = errno;
				Perror(stderr, "write failed", errno);
				badns |= (1 << ns);
				res_close();
				goto next_ns;
			}
			/*
			 * Receive length & response
			 */
read_len:
			cp = ans;
			len = INT16SZ;
			while ((n = read(s, (char *)cp, (int)len)) > 0) {
				cp += n;
				if ((len -= n) <= 0)
					break;
			}
			if (n <= 0) {
				terrno = errno;
				Perror(stderr, "read failed", errno);
				res_close();
				/*
				 * A long running process might get its TCP
				 * connection reset if the remote server was
				 * restarted.  Requery the server instead of
				 * trying a new one.  When there is only one
				 * server, this means that a query might work
				 * instead of failing.  We only allow one reset
				 * per query to prevent looping.
				 */
				if (terrno == ECONNRESET && !connreset) {
					connreset = 1;
					res_close();
					goto same_ns;