/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2015 Gary Mills
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All Rights Reserved   */

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <netdb.h>
#include "crossl.h"

/*
 * Kludge to time out quickly if there is no /etc/resolv.conf
 * and a TCP connection to the local DNS server fails.
 *
 * Moved function from res_send.c to res_mkquery.c.  This
 * solves a long timeout problem with nslookup.
 *
 * __areweinnamed is needed because there is a possibility that the
 * user might do bad things to resolv.conf and cause in.named to call
 * _confcheck and deadlock the server.
 */

int __areweinnamed()
{
        return (0);
}

static int _confcheck()
{
        int ns;
        struct stat rc_stat;
        struct sockaddr_in ns_sin;


        /* First, we check to see if /etc/resolv.conf exists.
         * If it doesn't, then localhost is mostlikely to be
         * the nameserver.
         */
        if (stat(_PATH_RESCONF, &rc_stat) == -1 && errno == ENOENT) {

                /* Next, we check to see if _res.nsaddr is set to loopback.
                 * If it isn't, it has been altered by the application
                 * explicitly and we then want to bail with success.
                 */
                if (__areweinnamed())
                        return (0);

                if (_res.nsaddr.sin_addr.S_un.S_addr == htonl(INADDR_LOOPBACK)) {

                        /* Lastly, we try to connect to the TCP port of the
                         * nameserver.  If this fails, then we know that
                         * DNS is misconfigured and we can quickly exit.
                         */
                        ns = socket(AF_INET, SOCK_STREAM, 0);
                        IN_SET_LOOPBACK_ADDR(&ns_sin);
                        ns_sin.sin_port = htons(NAMESERVER_PORT);
                        if (connect(ns, (struct sockaddr *) &ns_sin,
                                    sizeof ns_sin) == -1) {
                                (void) close(ns);
                                return(-1);
                        }
                        else {
                                (void) close(ns);
                                return(0);
                        }
                }

                return(0);
        }

        return (0);
}

/*
 * Form all types of queries.
 * Returns the size of the result or -1.
 */
int
res_mkquery(op, dname, class, type, data, datalen, newrr, buf, buflen)
        int op;                 /* opcode of query */
        char *dname;            /* domain name */
        int class, type;        /* class and type of query */
        char *data;             /* resource record data */
        int datalen;            /* length of data */
        struct rrec *newrr;     /* new rr for modify or append */
        char *buf;              /* buffer to put query */
        int buflen;             /* size of buffer */
{
        register HEADER *hp;
        register u_char *cp;
        register int n;
        u_char *dnptrs[10], **dpp, **lastdnptr;

#ifdef DEBUG
        if (_res.options & RES_DEBUG)
                printf("res_mkquery(%d, %s, %d, %d)\n", op, dname, class, type);
#endif /* DEBUG */

        /*
         * Check to see if we can bailout quickly.
         * Also rerun res_init if we failed in the past.
         */

        if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
                h_errno = NO_RECOVERY;
                return(-1);
        }

        if (_confcheck() == -1) {
                _res.options &= ~RES_INIT;
                h_errno = NO_RECOVERY;
                return(-1);
        }

        /*
         * Initialize header fields.
         */
        if ((buf == NULL) || (buflen < sizeof (HEADER)))
                return (-1);
#ifdef SYSV
        (void) memset(buf, 0, sizeof (HEADER));
#else
        bzero(buf, sizeof (HEADER));
#endif
        hp = (HEADER *) buf;
        hp->id = htons(++_res.id);
        hp->opcode = op;
        hp->pr = (_res.options & RES_PRIMARY) != 0;
        hp->rd = (_res.options & RES_RECURSE) != 0;
        hp->rcode = NOERROR;
        cp = (u_char *)(buf + sizeof (HEADER));
        buflen -= sizeof (HEADER);
        dpp = dnptrs;
        *dpp++ = (u_char *)buf;
        *dpp++ = NULL;
        lastdnptr = dnptrs + sizeof (dnptrs) / sizeof (dnptrs[0]);
        /*
         * perform opcode specific processing
         */
        switch (op) {
        case QUERY:
                if ((buflen -= QFIXEDSZ) < 0)
                        return (-1);
                if ((n = dn_comp((u_char *)dname, cp, buflen,
                    dnptrs, lastdnptr)) < 0)
                        return (-1);
                cp += n;
                buflen -= n;
                putshort(type, cp);
                cp += sizeof (u_short);
                putshort(class, cp);
                cp += sizeof (u_short);
                hp->qdcount = htons(1);
                if (op == QUERY || data == NULL)
                        break;
                /*
                 * Make an additional record for completion domain.
                 */
                buflen -= RRFIXEDSZ;
                if ((n = dn_comp((u_char *)data, cp, buflen,
                    dnptrs, lastdnptr)) < 0)
                        return (-1);
                cp += n;
                buflen -= n;
                putshort(T_NULL, cp);
                cp += sizeof (u_short);
                putshort(class, cp);
                cp += sizeof (u_short);
                putlong(0, cp);
                cp += sizeof (u_long);
                putshort(0, cp);
                cp += sizeof (u_short);
                hp->arcount = htons(1);
                break;

        case IQUERY:
                /*
                 * Initialize answer section
                 */
                if (buflen < 1 + RRFIXEDSZ + datalen)
                        return (-1);
                *cp++ = '\0';   /* no domain name */
                putshort(type, cp);
                cp += sizeof (u_short);
                putshort(class, cp);
                cp += sizeof (u_short);
                putlong(0, cp);
                cp += sizeof (u_long);
                putshort(datalen, cp);
                cp += sizeof (u_short);
                if (datalen) {
#ifdef SYSV
                        (void) memcpy((void *)cp, (void *)data, datalen);
#else
                        bcopy(data, cp, datalen);
#endif
                        cp += datalen;
                }
                hp->ancount = htons(1);
                break;

#ifdef ALLOW_UPDATES
        /*
         * For UPDATEM/UPDATEMA, do UPDATED/UPDATEDA followed by UPDATEA
         * (Record to be modified is followed by its replacement in msg.)
         */
        case UPDATEM:
        case UPDATEMA:

        case UPDATED:
                /*
                 * The res code for UPDATED and UPDATEDA is the same; user
                 * calls them differently: specifies data for UPDATED; server
                 * ignores data if specified for UPDATEDA.
                 */
        case UPDATEDA:
                buflen -= RRFIXEDSZ + datalen;
                if ((n = dn_comp((u_char *)dname, cp, buflen,
                    dnptrs, lastdnptr)) < 0)
                        return (-1);
                cp += n;
                putshort(type, cp);
                cp += sizeof (u_short);
                putshort(class, cp);
                cp += sizeof (u_short);
                putlong(0, cp);
                cp += sizeof (u_long);
                putshort(datalen, cp);
                cp += sizeof (u_short);
                if (datalen) {
#ifdef SYSV
                        memcpy((void *)cp, (void *)data, datalen);
#else
                        bcopy(data, cp, datalen);
#endif
                        cp += datalen;
                }
                if ((op == UPDATED) || (op == UPDATEDA)) {
                        hp->ancount = htons(0);
                        break;
                }
                /* Else UPDATEM/UPDATEMA, so drop into code for UPDATEA */

        case UPDATEA:   /* Add new resource record */
                buflen -= RRFIXEDSZ + datalen;
                if ((n = dn_comp((u_char *)dname, cp, buflen,
                    dnptrs, lastdnptr)) < 0)
                        return (-1);
                cp += n;
                putshort(newrr->r_type, cp);
                cp += sizeof (u_short);
                putshort(newrr->r_class, cp);
                cp += sizeof (u_short);
                putlong(0, cp);
                cp += sizeof (u_long);
                putshort(newrr->r_size, cp);
                cp += sizeof (u_short);
                if (newrr->r_size) {
#ifdef SYSV
                        memcpy((void *)cp, newrr->r_data, newrr->r_size);
#else
                        bcopy(newrr->r_data, cp, newrr->r_size);
#endif
                        cp += newrr->r_size;
                }
                hp->ancount = htons(0);
                break;

#endif /* ALLOW_UPDATES */
        }
        return ((char *)cp - buf);
}