res_comp.cpp

/*	$NetBSD: res_comp.c,v 1.6 2004/05/22 23:47:09 christos Exp $	*/

/*
 * Copyright (c) 1985, 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.
 */

/*
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Portions Copyright (c) 1996-1999 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 ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC 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.
 */

#include <arpa/nameser.h>
#include <ctype.h>
#include <netinet/in.h>
#include <string.h>
#include <unistd.h>

#include "resolv_private.h"

/*
 * Expand compressed domain name 'src' to full domain name.
 * 'msg' is a pointer to the begining of the message,
 * 'eom' points to the first location after the message,
 * 'dst' is a pointer to a buffer of size 'dstsiz' for the result.
 * Return size of compressed name or -1 if there was an error.
 */
int dn_expand(const uint8_t* msg, const uint8_t* eom, const uint8_t* src, char* dst, int dstsiz) {
    int n = ns_name_uncompress(msg, eom, src, dst, (size_t) dstsiz);

    if (n > 0 && dst[0] == '.') dst[0] = '\0';
    return (n);
}

/*
 * Pack domain name 'exp_dn' in presentation form into 'comp_dn'.
 * Return the size of the compressed name or -1.
 * 'length' is the size of the array pointed to by 'comp_dn'.
 */
int dn_comp(const char* src, uint8_t* dst, int dstsiz, uint8_t** dnptrs, uint8_t** lastdnptr) {
    return (ns_name_compress(src, dst, (size_t)dstsiz, (const uint8_t**)dnptrs,
                             (const uint8_t**)lastdnptr));
}

/*
 * Skip over a compressed domain name. Return the size or -1.
 */
int dn_skipname(const uint8_t* ptr, const uint8_t* eom) {
    const uint8_t* saveptr = ptr;

    if (ns_name_skip(&ptr, eom) == -1) return (-1);
    return (ptr - saveptr);
}

/*
 * Verify that a domain name uses an acceptable character set.
 */

/*
 * Note the conspicuous absence of ctype macros in these definitions.  On
 * non-ASCII hosts, we can't depend on string literals or ctype macros to
 * tell us anything about network-format data.  The rest of the BIND system
 * is not careful about this, but for some reason, we're doing it right here.
 */

/* BIONIC: We also accept underscores in the middle of labels.
 *         This extension is needed to make resolution on some VPN networks
 *         work properly.
 */

#define PERIOD 0x2e
#define hyphenchar(c) ((c) == 0x2d)
#define bslashchar(c) ((c) == 0x5c)
#define periodchar(c) ((c) == PERIOD)
#define asterchar(c) ((c) == 0x2a)
#define alphachar(c) (((c) >= 0x41 && (c) <= 0x5a) || ((c) >= 0x61 && (c) <= 0x7a))
#define digitchar(c) ((c) >= 0x30 && (c) <= 0x39)
#define underscorechar(c) ((c) == 0x5f)

#define borderchar(c) (alphachar(c) || digitchar(c))
#define middlechar(c) (borderchar(c) || hyphenchar(c) || underscorechar(c))
#define domainchar(c) ((c) > 0x20 && (c) < 0x7f)

int res_hnok(const char* dn) {
    int pch = PERIOD, ch = *dn++;

    while (ch != '\0') {
        int nch = *dn++;

        if (periodchar(ch)) {
            ;
        } else if (periodchar(pch)) {
            if (!borderchar(ch)) return (0);
        } else if (periodchar(nch) || nch == '\0') {
            if (!borderchar(ch)) return (0);
        } else {
            if (!middlechar(ch)) return (0);
        }
        pch = ch, ch = nch;
    }
    return (1);
}

/*
 * hostname-like (A, MX, WKS) owners can have "*" as their first label
 * but must otherwise be as a host name.
 */
int res_ownok(const char* dn) {
    if (asterchar(dn[0])) {
        if (periodchar(dn[1])) return (res_hnok(dn + 2));
        if (dn[1] == '\0') return (1);
    }
    return (res_hnok(dn));
}

/*
 * SOA RNAMEs and RP RNAMEs can have any printable character in their first
 * label, but the rest of the name has to look like a host name.
 */
int res_mailok(const char* dn) {
    int ch, escaped = 0;

    /* "." is a valid missing representation */
    if (*dn == '\0') return (1);

    /* otherwise <label>.<hostname> */
    while ((ch = *dn++) != '\0') {
        if (!domainchar(ch)) return (0);
        if (!escaped && periodchar(ch)) break;
        if (escaped)
            escaped = 0;
        else if (bslashchar(ch))
            escaped = 1;
    }
    if (periodchar(ch)) return (res_hnok(dn));
    return (0);
}

/*
 * This function is quite liberal, since RFC 1034's character sets are only
 * recommendations.
 */
int res_dnok(const char* dn) {
    int ch;

    while ((ch = *dn++) != '\0')
        if (!domainchar(ch)) return (0);
    return (1);
}