ns_forw.c

早期freebsd实现

#if !defined(lint) && !defined(SABER)
static char sccsid[] = "@(#)ns_forw.c	4.32 (Berkeley) 3/3/91";
static char rcsid[] = "$Id: ns_forw.c,v 4.9.1.8 1993/12/06 00:43:02 vixie Exp $";
#endif /* not lint */

/*
 * ++Copyright++ 1986
 * -
 * Copyright (c) 1986
 *    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--
 */

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

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

#include "named.h"

/*
 * Forward the query to get the answer since its not in the database.
 * Returns FW_OK if a request struct is allocated and the query sent.
 * Returns FW_DUP if this is a duplicate of a pending request. 
 * Returns FW_NOSERVER if there were no addresses for the nameservers.
 * Returns FW_SERVFAIL on malloc error or if asked to do something
 * dangerous, such as fwd to ourselves or fwd to the host that asked us.
 *
 * (no action is taken on errors and qpp is not filled in.)
 */
int
ns_forw(nsp, msg, msglen, fp, qsp, dfd, qpp, dname)
	struct databuf *nsp[];
	u_char *msg;
	int msglen;
	struct sockaddr_in *fp;
	struct qstream *qsp;
	int dfd;
	struct qinfo **qpp;
	char *dname;
{
	register struct qinfo *qp;
	HEADER *hp;
	u_int16_t id;
	int n;

	dprintf(3, (ddt, "ns_forw()\n"));


	hp = (HEADER *) msg;
	id = hp->id;
	/* Look at them all */
	for (qp = qhead; qp!=QINFO_NULL; qp = qp->q_link) {
		if (qp->q_id == id &&
		    bcmp((char *)&qp->q_from, fp, sizeof(qp->q_from)) == 0 &&
		    ((qp->q_cmsglen == 0 && qp->q_msglen == msglen &&
		     bcmp((char *)qp->q_msg+2, msg+2, msglen-2) == 0) ||
		    (qp->q_cmsglen == msglen &&
		     bcmp((char *)qp->q_cmsg+2, msg+2, msglen-2) == 0))) {
			dprintf(3, (ddt,
				    "forw: dropped DUP id=%d\n", ntohs(id)));
			stats[S_DUPQUERIES].cnt++;
			return (FW_DUP);
		}
	}

	qp = qnew();
	qp->q_from = *fp;	/* nslookup wants to know this */
	if ((n = nslookup(nsp, qp, dname, "ns_forw")) < 0) {
		dprintf(2, (ddt, "forw: nslookup reports danger\n"));
		qfree(qp);
		return (FW_SERVFAIL);
	} else if (n == 0 && !(forward_only && fwdtab)) {
		dprintf(2, (ddt, "forw: no nameservers found\n"));
		qfree(qp);
		return (FW_NOSERVER);
	}
	qp->q_stream = qsp;
	qp->q_curaddr = 0;
	qp->q_fwd = fwdtab;
	qp->q_dfd = dfd;
	qp->q_id = id;
	qp->q_expire = tt.tv_sec + RETRY_TIMEOUT*2;
	hp->id = qp->q_nsid = htons((u_int16_t)++nsid);
	hp->ancount = 0;
	hp->nscount = 0;
	hp->arcount = 0;
	if ((qp->q_msg = malloc((unsigned)msglen)) == NULL) {
		syslog(LOG_ERR, "forw: %m");
		qfree(qp);
		return (FW_SERVFAIL);
	}
	bcopy(msg, qp->q_msg, qp->q_msglen = msglen);
	if (!qp->q_fwd) {
		hp->rd = 0;
		qp->q_addr[0].stime = tt;
	}

#ifdef SLAVE_FORWARD
	if (forward_only)
		schedretry(qp, (time_t)slave_retry);
	else
#endif /* SLAVE_FORWARD */
	schedretry(qp, qp->q_fwd ?(2*RETRYBASE) :retrytime(qp));

	dprintf(1, (ddt,
		"forw: forw -> [%s].%d ds=%d nsid=%d id=%d %dms retry %dsec\n",
			inet_ntoa(Q_NEXTADDR(qp,0)->sin_addr),
			ntohs(Q_NEXTADDR(qp,0)->sin_port), ds,
			ntohs(qp->q_nsid), ntohs(qp->q_id),
			(qp->q_addr[0].nsdata != NULL)
				? qp->q_addr[0].nsdata->d_nstime
				: -1,
			qp->q_time - tt.tv_sec));
#ifdef DEBUG
	if (debug >= 10)
		fp_query((char *)msg, ddt);
#endif
	if (sendto(ds, msg, msglen, 0, (struct sockaddr *)Q_NEXTADDR(qp,0),
		   sizeof(struct sockaddr_in)) < 0) {
			dprintf(5, (ddt,
				    "error returning msg errno=%d\n", errno));
	}
	stats[S_OUTPKTS].cnt++;
	if (qpp)
		*qpp = qp;
	hp->rd = 1;
	return (0);
}

/* struct qdatagram *
 * aIsUs(addr)
 *	scan the datagramq (our list of interface addresses) for "addr"
 * returns:
 *	pointer to qdatagram entry or NULL if no match is found
 * notes:
 *	INADDR_ANY ([0.0.0.0]) is on the datagramq, so it's considered "us"
 * author:
 *	Paul Vixie (DECWRL) April 1991
 */
struct qdatagram *
aIsUs(addr)
	struct in_addr addr;
{
	struct qdatagram *dqp;

	for (dqp = datagramq;  dqp != QDATAGRAM_NULL;  dqp = dqp->dq_next) {
		if (addr.s_addr == dqp->dq_addr.s_addr) {
			return dqp;
		}
	}
	return NULL;
}

/* haveComplained(tag1, tag2)
 *	check to see if we have complained about (tag1,tag2) recently
 *	(note that these are declared as pointers but are never deref'd)
 * returns:
 *	boolean: have we complained recently?
 * side-effects:
 *	outdated complaint records removed from our static list
 * author:
 *	Paul Vixie (DECWRL) April 1991
 */
int
haveComplained(tag1, tag2)
	char *tag1, *tag2;
{
	struct complaint {
		char *tag1, *tag2;
		time_t expire;
		struct complaint *next;
	};
	static struct complaint *List = NULL;
	struct complaint *cur, *next, *prev;
	int r = 0;

	for (cur = List, prev = NULL;  cur;  prev = cur, cur = next) {
		next = cur->next;
		if (tt.tv_sec > cur->expire) {
			if (prev)
				prev->next = next;
			else
				List = next;
			free((char*) cur);
			cur = prev;
		} else if ((tag1 == cur->tag1) && (tag2 == cur->tag2)) {
			r++;
		}
	}
	if (!r) {
		cur = (struct complaint *)malloc(sizeof(struct complaint));
		cur->tag1 = tag1;
		cur->tag2 = tag2;
		cur->expire = tt.tv_sec + INIT_REFRESH;	/* "10 minutes" */
		cur->next = NULL;
		if (prev)
			prev->next = cur;
		else
			List = cur;
	}
	return r;
}

/* void
 * nslookupComplain(sysloginfo, queryname, complaint, dname, a_rr)
 *	Issue a complaint about a dangerous situation found by nslookup().
 * params:
 *	sysloginfo is a string identifying the complainant.
 *	queryname is the domain name associated with the problem.
 *	complaint is a string describing what is wrong.
 *	dname and a_rr are the problematic other name server.
 */
void
nslookupComplain(sysloginfo, queryname, complaint, dname, a_rr)
	char *sysloginfo, *queryname, *complaint, *dname;
	register struct databuf *a_rr;
{
	dprintf(2, (ddt, "NS '%s' %s\n", dname, complaint));
	if (sysloginfo && queryname && !haveComplained(queryname, complaint))
	{
		char buf[512];

		/* syslog only takes 5 params */
		sprintf(buf, "%s: query(%s) %s (%s:%s)",
			sysloginfo, queryname,
			complaint, dname, inet_ntoa(
			    *(struct in_addr*)a_rr->d_data
			));
		syslog(LOG_INFO, buf);
	}
}

/*
 * nslookup(nsp, qp, syslogdname, sysloginfo)
 *	Lookup the address for each nameserver in `nsp' and add it to
 * 	the list saved in the qinfo structure pointed to by `qp'.
 *	Omits information about nameservers that we shouldn't ask.
 *	Detects the following dangerous operations:
 *		One of the A records for one of the nameservers in nsp
 *		refers to the address of one of our own interfaces;
 *		One of the A records refers to the nameserver port on
 *		the host that asked us this question.
 * returns: the number of addresses added, or -1 if a dangerous operation
 *	is detected.
 * side effects:
 *	if a dangerous situation is detected and (syslogdname && sysloginfo),
 *	calls syslog.
 */
int
nslookup(nsp, qp, syslogdname, sysloginfo)
	struct databuf *nsp[];
	register struct qinfo *qp;
	char *syslogdname;
	char *sysloginfo;
{
	register struct namebuf *np;
	register struct databuf *dp, *nsdp;
	register struct qserv *qs;
	register int n, i;
	struct hashbuf *tmphtp;
	char *dname, *fname;
	int oldn, naddr, class, found_arr;
	time_t curtime;
	int qcomp();

	dprintf(3, (ddt, "nslookup(nsp=0x%x, qp=0x%x, \"%s\")\n",
		    nsp, qp, syslogdname));

	naddr = n = qp->q_naddr;
	curtime = (u_long) tt.tv_sec;
	while ((nsdp = *nsp++) != NULL) {
		class = nsdp->d_class;
		dname = (char *)nsdp->d_data;
		dprintf(3, (ddt, "nslookup: NS \"%s\" c=%d t=%d (0x%x)\n",
			    dname, class, nsdp->d_type, nsdp->d_flags));

		/* don't put in people we have tried */
		for (i = 0; i < qp->q_nusedns; i++) {
			if (qp->q_usedns[i] == nsdp) {
				dprintf(2, (ddt,
					    "skipping used NS w/name %s\n",
					    nsdp->d_data));
				goto skipserver;
			}
		}

		tmphtp = ((nsdp->d_flags & DB_F_HINT) ?fcachetab :hashtab);
		np = nlookup(dname, &tmphtp, &fname, 1);
		if (np == NULL || fname != dname) {
			dprintf(3, (ddt, "%s: not found %s %x\n",
				    dname, fname, np));
			continue;
		}
		found_arr = 0;
		oldn = n;

		/* look for name server addresses */
		for (dp = np->n_data;  dp != NULL;  dp = dp->d_next) {
			if (dp->d_type == T_CNAME && dp->d_class == class)
				goto skipserver;
			if (dp->d_type != T_A || dp->d_class != class)
				continue;
#ifdef NCACHE
			if (dp->d_rcode)
				continue;
#endif
			/*
			 * Don't use records that may become invalid to
			 * reference later when we do the rtt computation.
			 * Never delete our safety-belt information!
			 */
			if ((dp->d_zone == 0) &&
			    (dp->d_ttl < (curtime+900)) &&
			    !(dp->d_flags & DB_F_HINT) )
		        {
				dprintf(3, (ddt,
					    "nslookup: stale entry '%s'\n",
					    np->n_dname));
				/* Cache invalidate the NS RR's */
				if (dp->d_ttl < curtime)
					delete_all(np, class, T_A);
				n = oldn;
				break;
			}
#ifdef VALIDATE
			/* [e-mail] validation procedure, maintains a
			 * table of server names-addresses used recently
			 */
			store_name_addr(dname, (struct in_addr *)dp->d_data,
					syslogdname, sysloginfo);
#endif /*VALIDATE*/

			found_arr++;
			/* don't put in duplicates */
			qs = qp->q_addr;
			for (i = 0; i < n; i++, qs++)
				if (qs->ns_addr.sin_addr.s_addr ==
				    ((struct in_addr *)dp->d_data)->s_addr)
					goto skipaddr;
			qs->ns_addr.sin_family = AF_INET;
			qs->ns_addr.sin_port = ns_port;
			qs->ns_addr.sin_addr = *(struct in_addr *)dp->d_data;
			qs->ns = nsdp;
			qs->nsdata = dp;
			qp->q_addr[n].nretry = 0;	/* XXX - why not qs? */
			/*
			 * if we are being asked to fwd a query whose
			 * nameserver list includes our own name/address(es),
			 * then we have detected a lame delegation and rather
			 * than melt down the network and hose down the other
			 * servers (who will hose us in return), we'll return
			 * -1 here which will cause SERVFAIL to be sent to
			 * the client's resolver which will hopefully then
			 * shut up.
			 *
			 * (originally done in nsContainsUs by vix@dec mar92;
			 * moved into nslookup by apb@und jan1993)
			 */
			if (aIsUs(*(struct in_addr *)dp->d_data)) {
			    static char *complaint = "contains our address";
			    nslookupComplain(sysloginfo, syslogdname,
					complaint, dname, dp);
			    return -1;
			}
			/*
			 * If we want to forward to a host that asked us
			 * this question then either we or they are sick
			 * (unless they asked from some port other than
			 * their nameserver port).  (apb@und jan1993)
			 */
			if (bcmp((char *)&qp->q_from, &qs->ns_addr,
			    sizeof(qp->q_from)) == 0)
			{
			    static char *complaint = "forwarding loop";
			    nslookupComplain(sysloginfo, syslogdname,
					complaint, dname, dp);
			    return -1;
			}
			n++;
			if (n >= NSMAX)
				goto out;
	skipaddr:	;
		}
		dprintf(8, (ddt, "nslookup: %d ns addrs\n", n));
		if (found_arr == 0 && !(qp->q_flags & Q_SYSTEM))
			(void) sysquery(dname, class, T_A, NULL, 0);