1 /* Expanding a compressed DNS domain name to its presentation form.
2    Copyright (C) 1995-2022 Free Software Foundation, Inc.
3    This file is part of the GNU C Library.
4 
5    The GNU C Library is free software; you can redistribute it and/or
6    modify it under the terms of the GNU Lesser General Public
7    License as published by the Free Software Foundation; either
8    version 2.1 of the License, or (at your option) any later version.
9 
10    The GNU C Library is distributed in the hope that it will be useful,
11    but WITHOUT ANY WARRANTY; without even the implied warranty of
12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13    Lesser General Public License for more details.
14 
15    You should have received a copy of the GNU Lesser General Public
16    License along with the GNU C Library; if not, see
17    <https://www.gnu.org/licenses/>.  */
18 
19 /*
20  * Copyright (c) 1985, 1993
21  *    The Regents of the University of California.  All rights reserved.
22  *
23  * Redistribution and use in source and binary forms, with or without
24  * modification, are permitted provided that the following conditions
25  * are met:
26  * 1. Redistributions of source code must retain the above copyright
27  *    notice, this list of conditions and the following disclaimer.
28  * 2. Redistributions in binary form must reproduce the above copyright
29  *    notice, this list of conditions and the following disclaimer in the
30  *    documentation and/or other materials provided with the distribution.
31  * 4. Neither the name of the University nor the names of its contributors
32  *    may be used to endorse or promote products derived from this software
33  *    without specific prior written permission.
34  *
35  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
36  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
37  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
38  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
39  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
40  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
41  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
42  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
43  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
44  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
45  * SUCH DAMAGE.
46  */
47 
48 /*
49  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
50  *
51  * Permission to use, copy, modify, and distribute this software for any
52  * purpose with or without fee is hereby granted, provided that the above
53  * copyright notice and this permission notice appear in all copies, and that
54  * the name of Digital Equipment Corporation not be used in advertising or
55  * publicity pertaining to distribution of the document or software without
56  * specific, written prior permission.
57  *
58  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
59  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
60  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
61  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
62  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
63  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
64  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
65  * SOFTWARE.
66  */
67 
68 /*
69  * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
70  *
71  * Permission to use, copy, modify, and distribute this software for any
72  * purpose with or without fee is hereby granted, provided that the above
73  * copyright notice and this permission notice appear in all copies.
74  *
75  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
76  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
77  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
78  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
79  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
80  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
81  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
82  * SOFTWARE.
83  */
84 
85 #include <arpa/nameser.h>
86 #include <resolv.h>
87 #include <shlib-compat.h>
88 
89 /* Expand compressed domain name COMP_DN to full domain name.  MSG is
90    a pointer to the beginning of the message, EOMORIG points to the
91    first location after the message, EXP_DN is a pointer to a buffer
92    of size LENGTH for the result.  Returns size of compressed name or
93    -1 if there was an error.  */
94 int
___dn_expand(const unsigned char * msg,const unsigned char * eom,const unsigned char * src,char * dst,int dstsiz)95 ___dn_expand (const unsigned char *msg, const unsigned char *eom,
96               const unsigned char *src, char *dst, int dstsiz)
97 {
98   int n = __ns_name_uncompress (msg, eom, src, dst, (size_t) dstsiz);
99   if (n > 0 && dst[0] == '.')
100     dst[0] = '\0';
101   return n;
102 }
103 versioned_symbol (libc, ___dn_expand, dn_expand, GLIBC_2_34);
104 versioned_symbol (libc, ___dn_expand, __libc_dn_expand, GLIBC_PRIVATE);
105 libc_hidden_ver (___dn_expand, __libc_dn_expand);
106 
107 #if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_2)
108 compat_symbol (libresolv, ___dn_expand, dn_expand, GLIBC_2_0);
109 #endif
110 #if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_2, GLIBC_2_34)
111 compat_symbol (libresolv, ___dn_expand, __dn_expand, GLIBC_2_2);
112 #endif
113