/* Syntax checking for DNS domain names.
Copyright (C) 1995-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/*
* 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.
* 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.
*/
/*
* 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
* CONSORTIUM 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 <resolv.h>
#include <shlib-compat.h>
/* Return true if the string consists of printable ASCII characters
only. */
static bool
printable_string (const char *dn)
{
while (true)
{
char ch = *dn;
if (ch == '\0')
return true;
if (ch <= ' ' || ch > '~')
return false;
++dn;
}
}
/* Return true if DN points to a name consisting only of [0-9a-zA-Z_-]
characters. DN must be in DNS wire format, without
compression. */
static bool
binary_hnok (const unsigned char *dn)
{
while (true)
{
size_t label_length = *dn;
if (label_length == 0)
break;
++dn;
const unsigned char *label_end = dn + label_length;
do
{
unsigned char ch = *dn;
if (!(('0' <= ch && ch <= '9')
|| ('A' <= ch && ch <= 'Z')
|| ('a' <= ch && ch <= 'z')
|| ch == '-' || ch == '_'))
return false;
++dn;
}
while (dn < label_end);
}
return true;
}
/* Return true if the binary domain name has a first labels which
starts with '-'. */
static inline bool
binary_leading_dash (const unsigned char *dn)
{
return dn[0] > 0 && dn[1] == '-';
}
/* Return 1 if res_hnok is a valid host name. Labels must only
contain [0-9a-zA-Z_-] characters, and the name must not start with
a '-'. The latter is to avoid confusion with program options. */
int
___res_hnok (const char *dn)
{
unsigned char buf[NS_MAXCDNAME];
if (!printable_string (dn)
|| __ns_name_pton (dn, buf, sizeof (buf)) < 0
|| binary_leading_dash (buf))
return 0;
return binary_hnok (buf);
}
versioned_symbol (libc, ___res_hnok, res_hnok, GLIBC_2_34);
versioned_symbol (libc, ___res_hnok, __libc_res_hnok, GLIBC_PRIVATE);
libc_hidden_ver (___res_hnok, __libc_res_hnok)
#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_34)
compat_symbol (libresolv, ___res_hnok, __res_hnok, GLIBC_2_0);
#endif
/* 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)
{
unsigned char buf[NS_MAXCDNAME];
if (!printable_string (dn)
|| __ns_name_pton (dn, buf, sizeof (buf)) < 0
|| binary_leading_dash (buf))
return 0;
if (buf[0] == 1 && buf [1] == '*')
/* Skip over the leading "*." part. */
return binary_hnok (buf + 2);
else
return binary_hnok (buf);
}
versioned_symbol (libc, ___res_ownok, res_ownok, GLIBC_2_34);
#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_34)
compat_symbol (libresolv, ___res_ownok, __res_ownok, GLIBC_2_0);
#endif
/* SOA RNAMEs and RP RNAMEs can have any byte in their first label,
but the rest of the name has to look like a host name. */
int
___res_mailok (const char *dn)
{
unsigned char buf[NS_MAXCDNAME];
if (!printable_string (dn)
|| __ns_name_pton (dn, buf, sizeof (buf)) < 0)
return 0;
unsigned char label_length = buf[0];
/* "." is a valid missing representation */
if (label_length == 0)
return 1;
/* Skip over the first label. */
unsigned char *tail = buf + 1 + label_length;
if (*tail == 0)
/* More than one label is required (except for "."). */
return 0;
return binary_hnok (tail);
}
versioned_symbol (libc, ___res_mailok, res_mailok, GLIBC_2_34);
#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_34)
compat_symbol (libresolv, ___res_mailok, __res_mailok, GLIBC_2_0);
#endif
/* Return 1 if DN is a syntactically valid domain name. Empty names
are accepted. */
int
___res_dnok (const char *dn)
{
unsigned char buf[NS_MAXCDNAME];
return printable_string (dn) && __ns_name_pton (dn, buf, sizeof (buf)) >= 0;
}
versioned_symbol (libc, ___res_dnok, res_dnok, GLIBC_2_34);
versioned_symbol (libc, ___res_dnok, __libc_res_dnok, GLIBC_PRIVATE);
libc_hidden_ver (___res_dnok, __libc_res_dnok)
#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_34)
compat_symbol (libresolv, ___res_dnok, __res_dnok, GLIBC_2_0);
#endif