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[netbsd-mini2440.git] / external / bsd / libbind / dist / nameser / ns_samedomain.c
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1 /* $NetBSD$ */
3 /*
4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
5 * Copyright (c) 1995,1999 by Internet Software Consortium.
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
20 #ifndef lint
21 static const char rcsid[] = "Id: ns_samedomain.c,v 1.6 2005/04/27 04:56:40 sra Exp";
22 #endif
24 #include "port_before.h"
26 #include <sys/types.h>
27 #include <arpa/nameser.h>
28 #include <errno.h>
29 #include <string.h>
31 #include "port_after.h"
33 /*%
34 * Check whether a name belongs to a domain.
36 * Inputs:
37 *\li a - the domain whose ancestory is being verified
38 *\li b - the potential ancestor we're checking against
40 * Return:
41 *\li boolean - is a at or below b?
43 * Notes:
44 *\li Trailing dots are first removed from name and domain.
45 * Always compare complete subdomains, not only whether the
46 * domain name is the trailing string of the given name.
48 *\li "host.foobar.top" lies in "foobar.top" and in "top" and in ""
49 * but NOT in "bar.top"
52 int
53 ns_samedomain(const char *a, const char *b) {
54 size_t la, lb;
55 int diff, i, escaped;
56 const char *cp;
58 la = strlen(a);
59 lb = strlen(b);
61 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */
62 if (la != 0U && a[la - 1] == '.') {
63 escaped = 0;
64 /* Note this loop doesn't get executed if la==1. */
65 for (i = la - 2; i >= 0; i--)
66 if (a[i] == '\\') {
67 if (escaped)
68 escaped = 0;
69 else
70 escaped = 1;
71 } else
72 break;
73 if (!escaped)
74 la--;
77 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */
78 if (lb != 0U && b[lb - 1] == '.') {
79 escaped = 0;
80 /* note this loop doesn't get executed if lb==1 */
81 for (i = lb - 2; i >= 0; i--)
82 if (b[i] == '\\') {
83 if (escaped)
84 escaped = 0;
85 else
86 escaped = 1;
87 } else
88 break;
89 if (!escaped)
90 lb--;
93 /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */
94 if (lb == 0U)
95 return (1);
97 /* 'b' longer than 'a' means 'a' can't be in 'b'. */
98 if (lb > la)
99 return (0);
101 /* 'a' and 'b' being equal at this point indicates sameness. */
102 if (lb == la)
103 return (strncasecmp(a, b, lb) == 0);
105 /* Ok, we know la > lb. */
107 diff = la - lb;
110 * If 'a' is only 1 character longer than 'b', then it can't be
111 * a subdomain of 'b' (because of the need for the '.' label
112 * separator).
114 if (diff < 2)
115 return (0);
118 * If the character before the last 'lb' characters of 'b'
119 * isn't '.', then it can't be a match (this lets us avoid
120 * having "foobar.com" match "bar.com").
122 if (a[diff - 1] != '.')
123 return (0);
126 * We're not sure about that '.', however. It could be escaped
127 * and thus not a really a label separator.
129 escaped = 0;
130 for (i = diff - 2; i >= 0; i--)
131 if (a[i] == '\\') {
132 if (escaped)
133 escaped = 0;
134 else
135 escaped = 1;
136 } else
137 break;
138 if (escaped)
139 return (0);
141 /* Now compare aligned trailing substring. */
142 cp = a + diff;
143 return (strncasecmp(cp, b, lb) == 0);
147 * is "a" a subdomain of "b"?
150 ns_subdomain(const char *a, const char *b) {
151 return (ns_samename(a, b) != 1 && ns_samedomain(a, b));
155 * make a canonical copy of domain name "src"
157 * notes:
158 * \code
159 * foo -> foo.
160 * foo. -> foo.
161 * foo.. -> foo.
162 * foo\. -> foo\..
163 * foo\\. -> foo\\.
164 * \endcode
168 ns_makecanon(const char *src, char *dst, size_t dstsize) {
169 size_t n = strlen(src);
171 if (n + sizeof "." > dstsize) { /*%< Note: sizeof == 2 */
172 errno = EMSGSIZE;
173 return (-1);
175 strcpy(dst, src);
176 while (n >= 1U && dst[n - 1] == '.') /*%< Ends in "." */
177 if (n >= 2U && dst[n - 2] == '\\' && /*%< Ends in "\." */
178 (n < 3U || dst[n - 3] != '\\')) /*%< But not "\\." */
179 break;
180 else
181 dst[--n] = '\0';
182 dst[n++] = '.';
183 dst[n] = '\0';
184 return (0);
188 * determine whether domain name "a" is the same as domain name "b"
190 * return:
191 *\li -1 on error
192 *\li 0 if names differ
193 *\li 1 if names are the same
197 ns_samename(const char *a, const char *b) {
198 char ta[NS_MAXDNAME], tb[NS_MAXDNAME];
200 if (ns_makecanon(a, ta, sizeof ta) < 0 ||
201 ns_makecanon(b, tb, sizeof tb) < 0)
202 return (-1);
203 if (strcasecmp(ta, tb) == 0)
204 return (1);
205 else
206 return (0);
209 /*! \file */