1 /* HOSTALIASES-based name resolution. Internal function.
2 Copyright (C) 2015-2023 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) 1988, 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 <ctype.h>
87 #include <resolv-internal.h>
88 #include <resolv_context.h>
89 #include <stdio.h>
90 #include <stdlib.h>
91 #include <string.h>
92
93 const char *
94 __res_context_hostalias (struct resolv_context *ctx,
95 const char *name, char *dst, size_t siz)
96 {
97 char *file, *cp1, *cp2;
98 char buf[BUFSIZ];
99 FILE *fp;
100
101 if (ctx->resp->options & RES_NOALIASES)
102 return NULL;
103 file = getenv ("HOSTALIASES");
104 if (file == NULL || (fp = fopen (file, "rce")) == NULL)
105 return NULL;
106 buf[sizeof (buf) - 1] = '\0';
107 while (__fgets_unlocked (buf, sizeof (buf), fp))
108 {
109 for (cp1 = buf; *cp1 && !isspace (*cp1); ++cp1)
110 ;
111 if (!*cp1)
112 break;
113 *cp1 = '\0';
114 if (__libc_ns_samename (buf, name) == 1)
115 {
116 while (isspace (*++cp1))
117 ;
118 if (!*cp1)
119 break;
120 for (cp2 = cp1 + 1; *cp2 && !isspace (*cp2); ++cp2)
121 ;
122 *cp2 = '\0';
123 strncpy (dst, cp1, siz - 1);
124 dst[siz - 1] = '\0';
125 fclose (fp);
126 return dst;
127 }
128 }
129 fclose (fp);
130 return NULL;
131 }
132 libc_hidden_def (__res_context_hostalias)