getinfo.c

一个可用的dns服务器源代码

/*
 * ++Copyright++ 1985, 1989
 * -
 * Copyright (c) 1985, 1989
 *    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--
 */

#ifndef lint
static char sccsid[] = "@(#)getinfo.c	5.26 (Berkeley) 3/21/91";
static char rcsid[] = "$Id: getinfo.c,v 8.6 1996/12/02 09:17:24 vixie Exp $";
#endif /* not lint */

/*
 ******************************************************************************
 *
 *  getinfo.c --
 *
 *	Routines to create requests to name servers
 *	and interpret the answers.
 *
 *	Adapted from 4.3BSD BIND gethostnamadr.c
 *
 ******************************************************************************
 */

#ifndef WINNT
#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#endif 
#include <nameser.h>
#include <inet.h>
#include <resolv.h>
#include <stdio.h>
#include <ctype.h>
#include "res.h"
#include "portability.h"

extern char *_res_resultcodes[];
extern char *res_skip();

static char *addr_list[MAXADDRS + 1];

static char *host_aliases[MAXALIASES];
static int   host_aliases_len[MAXALIASES];
static u_char  hostbuf[BUFSIZ+1];

typedef struct {
    char *name;
    char *domain[MAXDOMAINS];
    int   numDomains;
    char *address[MAXADDRS];
    int   numAddresses;
} ServerTable;

ServerTable server[MAXSERVERS];

typedef union {
    HEADER qb1;
    u_char qb2[PACKETSZ*2];
} querybuf;

typedef union {
    int32_t al;
    char ac;
} align;

#define GetShort(cp)	_getshort(cp); cp += INT16SZ;

/*
 * Forward references
 */

int GetHostDomain(struct in_addr *nsAddrPtr, int queryClass, int queryType, char *name, 
              char *domain, HostInfo *hostPtr, Boolean isServer);
static int GetAnswer(struct in_addr	*nsAddrPtr, int queryType, char *msg, int msglen, Boolean iquery, 
                     register HostInfo	*hostPtr, Boolean isServer);


/*
 ******************************************************************************
 *
 *  GetAnswer --
 *
 *	Interprets an answer packet and retrieves the following
 *	information:
 *
 *  Results:
 *      SUCCESS         the info was retrieved.
 *      NO_INFO         the packet did not contain an answer.
 *	NONAUTH		non-authoritative information was found.
 *      ERROR           the answer was malformed.
 *      Other errors    returned in the packet header.
 *
 ******************************************************************************
 */

static int
GetAnswer(nsAddrPtr, queryType, msg, msglen, iquery, hostPtr, isServer)
    struct in_addr	*nsAddrPtr;
    char		*msg;
    int			queryType;
    int			msglen;
    Boolean		iquery;
    register HostInfo	*hostPtr;
    Boolean		isServer;
{
    register HEADER	*headerPtr;
    register u_char	*cp;
    querybuf		answer;
    char		**aliasPtr;
    u_char		*eom, *bp;
    char		**addrPtr;
    char		*namePtr;
    char		*dnamePtr;
    int			type, class;
    int			qdcount, ancount, arcount, nscount, buflen;
    int			origClass;
    int			numAliases = 0;
    int			numAddresses = 0;
    int			n, i, j;
    int			len;
    int			dlen;
    int			status;
    int			numServers;
    Boolean		haveAnswer;
    Boolean		printedAnswers = FALSE;

#ifndef GUI
 filePtr = stdout;
#else
 filePtr = outputfile;
#endif
    /*
     *  If the hostPtr was used before, free up the calloc'd areas.
     */
    FreeHostInfoPtr(hostPtr);

    status = SendRequest(nsAddrPtr, msg, msglen, (char *) &answer,
			    sizeof(answer), &n);

    if (status != SUCCESS) {
	    if (_res.options & RES_DEBUG2)
		    printf("SendRequest failed\n");
	    return (status);
    }
    eom = (u_char *) &answer + n;

    headerPtr = (HEADER *) &answer;

    if (headerPtr->rcode != NOERROR) {
	return (headerPtr->rcode);
    }

    qdcount = ntohs( (u_short) headerPtr->qdcount);
    ancount = ntohs( (u_short) headerPtr->ancount);
    arcount = ntohs( (u_short) headerPtr->arcount);
    nscount = ntohs( (u_short) headerPtr->nscount);

    /*
     * If there are no answer, n.s. or additional records
     * then return with an error.
     */
    if (ancount == 0 && nscount == 0 && arcount == 0) {
	return (NO_INFO);
    }


    bp	   = hostbuf;
    buflen = sizeof(hostbuf);
    cp	   = (u_char *) &answer + HFIXEDSZ;

    /* Skip over question section. */
    while (qdcount-- > 0) {
	cp += dn_skipname(cp, eom) + QFIXEDSZ;
    }

    aliasPtr	= host_aliases;
    addrPtr	= addr_list;
    haveAnswer	= FALSE;

    /*
     * Scan through the answer resource records.
     * Answers for address query types are saved.
     * Other query type answers are just printed.
     */
    if (ancount != 0) {
	if (!isServer && !headerPtr->aa) {
#ifndef GUI
	    printf("Non-authoritative answer:\n");
#else
	    fprintf(outputfile,"Non-authoritative answer:\n");
#endif
	}

	if (queryType != T_A && !(iquery && queryType == T_PTR)) {
	    while (--ancount >= 0 && cp < eom) {
		if ((cp = (u_char *)Print_rr(cp,
		    (char *)&answer, eom, filePtr)) == NULL) {
		    return(ERROR);
		}
	    }
	    printedAnswers = TRUE;
	} else {
	    while (--ancount >= 0 && cp < eom) {
		n = dn_expand(answer.qb2, eom, cp, (char *)bp, buflen);
		if (n < 0) {
		    return(ERROR);
		}
		cp   += n;
		type  = GetShort(cp);
		class = GetShort(cp);
		cp   += INT32SZ;	/* skip TTL */
		dlen  = GetShort(cp);
		if (type == T_CNAME) {
		    /*
		     * Found an alias.
		     */
		    cp += dlen;
		    if (aliasPtr >= &host_aliases[MAXALIASES-1]) {
			continue;
		    }
		    *aliasPtr++ = (char *)bp;
		    n = strlen((char *)bp) + 1;
		    host_aliases_len[numAliases] = n;
		    numAliases++;
		    bp += n;
		    buflen -= n;
		    continue;
		} else if (type == T_PTR) {
		    /*
		     *  Found a "pointer" to the real name.
		     */
		    n = dn_expand(answer.qb2, eom, cp, (char *)bp, buflen);
		    if (n < 0) {
			cp += n;
			continue;
		    }
		    cp += n;
		    len = strlen((char *)bp) + 1;
		    hostPtr->name = Calloc(1, len);
		    bcopy(bp, hostPtr->name, len);
		    haveAnswer = TRUE;
		    break;
		} else if (type != T_A) {
		    cp += dlen;
		    continue;
		}
		if (haveAnswer) {
		    /*
		     * If we've already got 1 address, we aren't interested
		     * in addresses with a different length or class.
		     */
		    if (dlen != hostPtr->addrLen) {
			cp += dlen;
			continue;
		    }
		    if (class != origClass) {
			cp += dlen;
			continue;
		    }
		} else {
		    /*
		     * First address: record its length and class so we
		     * only save additonal ones with the same attributes.
		     */
		    hostPtr->addrLen = dlen;
		    origClass = class;
		    hostPtr->addrType = (class == C_IN) ? AF_INET : AF_UNSPEC;
		    len = strlen((char *)bp) + 1;
		    hostPtr->name = Calloc(1, len);
		    bcopy(bp, hostPtr->name, len);
		}
		bp += (((u_int32_t)bp) % sizeof(align));

		if (bp + dlen >= &hostbuf[sizeof(hostbuf)]) {
		    if (_res.options & RES_DEBUG) {
			printf("Size (%d) too big\n", dlen);
		    }
		    break;
		}
		if (numAddresses >= MAXADDRS) {
#ifndef GUI
			fprintf(stderr,"MAXADDRS exceeded: skipping address\n");
#else
			fprintf(outputfile,"MAXADDRS exceeded: skipping address\n");
#endif
			cp += dlen;
			continue;
		}
		bcopy(cp, *addrPtr++ = (char *)bp, dlen);
		bp +=dlen;
		cp += dlen;
		numAddresses++;
		haveAnswer = TRUE;
	    }
	}
    }

    if ((queryType == T_A || queryType == T_PTR) && haveAnswer) {

	/*
	 *  Go through the alias and address lists and return them
	 *  in the hostPtr variable.
	 */

	if (numAliases > 0) {
	    hostPtr->aliases =
		(char **) Calloc(1 + numAliases, sizeof(char *));
	    for (i = 0; i < numAliases; i++) {
		hostPtr->aliases[i] = Calloc(1, host_aliases_len[i]);
		bcopy(host_aliases[i],
		      hostPtr->aliases[i],
		      host_aliases_len[i]);
	    }
	    hostPtr->aliases[i] = NULL;
	}
	if (numAddresses > 0) {
	    hostPtr->addrList =
		(char **)Calloc(1+numAddresses, sizeof(char *));
	    for (i = 0; i < numAddresses; i++) {
		hostPtr->addrList[i] = Calloc(1, hostPtr->addrLen);
		bcopy(addr_list[i], hostPtr->addrList[i], hostPtr->addrLen);
	    }
	    hostPtr->addrList[i] = NULL;
	}
#ifdef verbose
	if (headerPtr->aa || nscount == 0) {
	    hostPtr->servers = NULL;
	    return (SUCCESS);
	}
#else
	hostPtr->servers = NULL;
	return (SUCCESS);
#endif
    }

    /*
     * At this point, for the T_A query type, only empty answers remain.
     * For other query types, additional information might be found
     * in the additional resource records part.
     */

    if (!headerPtr->aa && (queryType != T_A) && (nscount > 0 || arcount > 0)) {
	if (printedAnswers) {
	    putchar('\n');
	}
#ifndef GUI
	printf("Authoritative answers can be found from:\n");
#else
	fprintf(outputfile,"Authoritative answers can be found from:\n");
#endif
    }

    cp = (u_char *)res_skip((char *) &answer, 2, eom);

    numServers = 0;
    if (queryType != T_A) {
	/*
	 * If we don't need to save the record, just print it.
	 */
	while (--nscount >= 0 && cp < eom) {
	    if ((cp = (u_char *)Print_rr(cp,
		(char *) &answer, eom, filePtr)) == NULL) {
		return(ERROR);
	    }
	}
    } else {
	while (--nscount >= 0 && cp < eom) {
	    /*
	     *  Go through the NS records and retrieve the names of hosts
	     *  that serve the requested domain.
	     */

	    n = dn_expand(answer.qb2, eom, cp, (char *)bp, buflen);
	    if (n < 0) {
		return(ERROR);
	    }
	    cp += n;
	    len = strlen((char *)bp) + 1;
	    dnamePtr = Calloc(1, len);   /* domain name */
	    bcopy(bp, dnamePtr, len);

	    type  = GetShort(cp);
	    class = GetShort(cp);
	    cp   += INT32SZ;	/* skip TTL */
	    dlen  = GetShort(cp);

	    if (type != T_NS) {
		cp += dlen;
	    } else {