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c79327bf00
During package parsing, only the binary representation is available, and it is convenient to check that directly for conformance with host name requirements. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
225 lines
8.1 KiB
C
225 lines
8.1 KiB
C
/* Syntax checking for DNS domain names.
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Copyright (C) 1995-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/*
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* Copyright (c) 1985, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Portions Copyright (c) 1993 by Digital Equipment Corporation.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies, and that
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* the name of Digital Equipment Corporation not be used in advertising or
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* publicity pertaining to distribution of the document or software without
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* specific, written prior permission.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
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* WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
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* CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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* SOFTWARE.
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*/
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/*
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* Portions Copyright (c) 1996-1999 by Internet Software Consortium.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
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* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
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* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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* SOFTWARE.
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*/
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#include <arpa/nameser.h>
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#include <resolv.h>
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#include <shlib-compat.h>
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/* Return true if the string consists of printable ASCII characters
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only. */
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static bool
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printable_string (const char *dn)
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{
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while (true)
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{
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char ch = *dn;
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if (ch == '\0')
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return true;
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if (ch <= ' ' || ch > '~')
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return false;
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++dn;
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}
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}
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/* Return true if DN points to a name consisting only of [0-9a-zA-Z_-]
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characters. DN must be in DNS wire format, without
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compression. */
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static bool
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binary_hnok (const unsigned char *dn)
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{
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while (true)
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{
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size_t label_length = *dn;
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if (label_length == 0)
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break;
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++dn;
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const unsigned char *label_end = dn + label_length;
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do
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{
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unsigned char ch = *dn;
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if (!(('0' <= ch && ch <= '9')
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|| ('A' <= ch && ch <= 'Z')
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|| ('a' <= ch && ch <= 'z')
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|| ch == '-' || ch == '_'))
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return false;
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++dn;
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}
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while (dn < label_end);
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}
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return true;
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}
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/* Return true if the binary domain name has a first labels which
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starts with '-'. */
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static inline bool
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binary_leading_dash (const unsigned char *dn)
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{
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return dn[0] > 0 && dn[1] == '-';
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}
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bool
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__res_binary_hnok (const unsigned char *dn)
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{
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return !binary_leading_dash (dn) && binary_hnok (dn);
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}
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/* Return 1 if res_hnok is a valid host name. Labels must only
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contain [0-9a-zA-Z_-] characters, and the name must not start with
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a '-'. The latter is to avoid confusion with program options. */
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int
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___res_hnok (const char *dn)
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{
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unsigned char buf[NS_MAXCDNAME];
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return (printable_string (dn)
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&& __ns_name_pton (dn, buf, sizeof (buf)) >= 0
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&& __res_binary_hnok (buf));
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}
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versioned_symbol (libc, ___res_hnok, res_hnok, GLIBC_2_34);
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versioned_symbol (libc, ___res_hnok, __libc_res_hnok, GLIBC_PRIVATE);
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libc_hidden_ver (___res_hnok, __libc_res_hnok)
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#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_34)
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compat_symbol (libresolv, ___res_hnok, __res_hnok, GLIBC_2_0);
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#endif
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/* Hostname-like (A, MX, WKS) owners can have "*" as their first label
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but must otherwise be as a host name. */
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int
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___res_ownok (const char *dn)
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{
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unsigned char buf[NS_MAXCDNAME];
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if (!printable_string (dn)
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|| __ns_name_pton (dn, buf, sizeof (buf)) < 0
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|| binary_leading_dash (buf))
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return 0;
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if (buf[0] == 1 && buf [1] == '*')
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/* Skip over the leading "*." part. */
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return binary_hnok (buf + 2);
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else
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return binary_hnok (buf);
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}
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versioned_symbol (libc, ___res_ownok, res_ownok, GLIBC_2_34);
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#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_34)
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compat_symbol (libresolv, ___res_ownok, __res_ownok, GLIBC_2_0);
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#endif
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/* SOA RNAMEs and RP RNAMEs can have any byte in their first label,
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but the rest of the name has to look like a host name. */
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int
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___res_mailok (const char *dn)
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{
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unsigned char buf[NS_MAXCDNAME];
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if (!printable_string (dn)
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|| __ns_name_pton (dn, buf, sizeof (buf)) < 0)
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return 0;
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unsigned char label_length = buf[0];
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/* "." is a valid missing representation */
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if (label_length == 0)
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return 1;
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/* Skip over the first label. */
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unsigned char *tail = buf + 1 + label_length;
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if (*tail == 0)
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/* More than one label is required (except for "."). */
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return 0;
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return binary_hnok (tail);
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}
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versioned_symbol (libc, ___res_mailok, res_mailok, GLIBC_2_34);
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#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_34)
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compat_symbol (libresolv, ___res_mailok, __res_mailok, GLIBC_2_0);
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#endif
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/* Return 1 if DN is a syntactically valid domain name. Empty names
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are accepted. */
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int
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___res_dnok (const char *dn)
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{
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unsigned char buf[NS_MAXCDNAME];
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return printable_string (dn) && __ns_name_pton (dn, buf, sizeof (buf)) >= 0;
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}
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versioned_symbol (libc, ___res_dnok, res_dnok, GLIBC_2_34);
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versioned_symbol (libc, ___res_dnok, __libc_res_dnok, GLIBC_PRIVATE);
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libc_hidden_ver (___res_dnok, __libc_res_dnok)
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#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_34)
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compat_symbol (libresolv, ___res_dnok, __res_dnok, GLIBC_2_0);
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#endif
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