/*
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation. Portions created by Netscape are
 * Copyright (C) 1998-1999 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s):
 */
/*
 *  Copyright (c) 1995 Regents of the University of Michigan.
 *  All rights reserved.
 */
/*
 * nsldapi_getdxbyname - retrieve DX records from the DNS (from
 * TXT records for now)
 */

#include <stdio.h>

#ifdef LDAP_DNS

XXX not MT-safe XXX

#include <string.h>
#include <ctype.h>

#ifdef macintosh
#include <stdlib.h>
#include "macos.h"
#endif /* macintosh */

#ifdef _WINDOWS
#include <windows.h>
#endif

#if !defined(macintosh) && !defined(DOS) && !defined( _WINDOWS )
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <resolv.h>
#endif
#include "ldap-int.h"

#if defined( DOS )
#include "msdos.h"
#endif /* DOS */


#ifdef NEEDPROTOS
static char ** decode_answer( unsigned char *answer, int len );
#else /* NEEDPROTOS */
static char **decode_answer();
#endif /* NEEDPROTOS */

extern int h_errno;
extern char *h_errlist[];


#define MAX_TO_SORT     32


/*
 * nsldapi_getdxbyname - lookup DNS DX records for domain and return an ordered
 *      array.
 */
char **
nsldapi_getdxbyname( char *domain )
{
    unsigned char       buf[ PACKETSZ ];
    char                **dxs;
    int                 rc;

    LDAPDebug( LDAP_DEBUG_TRACE, "nsldapi_getdxbyname( %s )\n", domain, 0, 0 );

    memset( buf, 0, sizeof( buf ));

    /* XXX not MT safe XXX */
    if (( rc = res_search( domain, C_IN, T_TXT, buf, sizeof( buf ))) < 0
                || ( dxs = decode_answer( buf, rc )) == NULL ) {
        /*
         * punt:  return list conisting of the original domain name only
         */
        if (( dxs = (char **)NSLDAPI_MALLOC( 2 * sizeof( char * ))) == NULL ||
                ( dxs[ 0 ] = nsldapi_strdup( domain )) == NULL ) {
            if ( dxs != NULL ) {
                NSLDAPI_FREE( dxs );
            }
            dxs = NULL;
        } else {
            dxs[ 1 ] = NULL;
        }
    }

    return( dxs );
}


static char **
decode_answer( unsigned char *answer, int len )
{
    HEADER              *hp;
    char                buf[ 256 ], **dxs;
    unsigned char       *eom, *p;
    int                 ancount, err, rc, type, class, dx_count, rr_len;
    int                 dx_pref[ MAX_TO_SORT ];

#ifdef LDAP_DEBUG
    if ( ldap_debug & LDAP_DEBUG_PACKETS ) {
/*      __p_query( answer );    */
    }
#endif /* LDAP_DEBUG */

    dxs = NULL;
    hp = (HEADER *)answer;
    eom = answer + len;

    if ( ntohs( hp->qdcount ) != 1 ) {
        h_errno = NO_RECOVERY;
        return( NULL );
    }

    ancount = ntohs( hp->ancount );
    if ( ancount < 1 ) {
        h_errno = NO_DATA;
        return( NULL );
    }

    /*
     * skip over the query
     */
    p = answer + HFIXEDSZ;
    if (( rc = dn_expand( answer, eom, p, buf, sizeof( buf ))) < 0 ) {
        h_errno = NO_RECOVERY;
        return( NULL );
    }
    p += ( rc + QFIXEDSZ );

    /*
     * pull out the answers we are interested in
     */
    err = dx_count = 0;
    while ( ancount > 0 && err == 0 && p < eom ) {
        if (( rc = dn_expand( answer, eom, p, buf, sizeof( buf ))) < 0 ) {
            err = NO_RECOVERY;
            continue;
        }
        p += rc;        /* skip over name */
        type = _getshort( p );
        p += INT16SZ;
        class = _getshort( p );
        p += INT16SZ;
        p += INT32SZ;           /* skip over TTL */
        rr_len = _getshort( p );
        p += INT16SZ;
        if ( class == C_IN && type == T_TXT ) {
            int         i, n, pref, txt_len;
            char        *q, *r;

            q = (char *)p;
            while ( q < (char *)p + rr_len && err == 0 ) {
                if ( *q >= 3 && strncasecmp( q + 1, "dx:", 3 ) == 0 ) {
                    txt_len = *q - 3;
                    r = q + 4;
                    while ( isspace( *r )) {
                        ++r;
                        --txt_len;
                    }
                    pref = 0;
                    while ( isdigit( *r )) {
                        pref *= 10;
                        pref += ( *r - '0' );
                        ++r;
                        --txt_len;
                    }
                    if ( dx_count < MAX_TO_SORT - 1 ) {
                        dx_pref[ dx_count ] = pref;
                    }
                    while ( isspace( *r )) {
                        ++r;
                        --txt_len;
                    }
                    if ( dx_count == 0 ) {
                        dxs = (char **)NSLDAPI_MALLOC( 2 * sizeof( char * ));
                    } else {
                        dxs = (char **)NSLDAPI_REALLOC( dxs,
                                ( dx_count + 2 ) * sizeof( char * ));
                    }
                    if ( dxs == NULL || ( dxs[ dx_count ] =
                            (char *)NSLDAPI_CALLOC( 1, txt_len + 1 ))
                            == NULL ) {
                        err = NO_RECOVERY;
                        continue;
                    }
                    SAFEMEMCPY( dxs[ dx_count ], r, txt_len );
                    dxs[ ++dx_count ] = NULL;
                }
                q += ( *q + 1 );        /* move past last TXT record */
            }
        }
        p += rr_len;
    }

    if ( err == 0 ) {
        if ( dx_count == 0 ) {
            err = NO_DATA;
        } else {
            /*
             * sort records based on associated preference value
             */
            int         i, j, sort_count, tmp_pref;
            char        *tmp_dx;

            sort_count = ( dx_count < MAX_TO_SORT ) ? dx_count : MAX_TO_SORT;
            for ( i = 0; i < sort_count; ++i ) {
                for ( j = i + 1; j < sort_count; ++j ) {
                    if ( dx_pref[ i ] > dx_pref[ j ] ) {
                        tmp_pref = dx_pref[ i ];
                        dx_pref[ i ] = dx_pref[ j ];
                        dx_pref[ j ] = tmp_pref;
                        tmp_dx = dxs[ i ];
                        dxs[ i ] = dxs[ j ];
                        dxs[ j ] = tmp_dx;
                    }
                }
            }
        }
    }

    h_errno = err;
    return( dxs );
}

#endif /* LDAP_DNS */