2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (c) 1995,1999 by Internet Software Consortium.
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
15 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
19 static const char rcsid
[] = "$Id: ns_samedomain.c,v 1.6 2005/04/27 04:56:40 sra Exp $";
22 #include "port_before.h"
24 #include <sys/types.h>
25 #include <arpa/nameser.h>
29 #include "port_after.h"
32 * Check whether a name belongs to a domain.
35 *\li a - the domain whose ancestory is being verified
36 *\li b - the potential ancestor we're checking against
39 *\li boolean - is a at or below b?
42 *\li Trailing dots are first removed from name and domain.
43 * Always compare complete subdomains, not only whether the
44 * domain name is the trailing string of the given name.
46 *\li "host.foobar.top" lies in "foobar.top" and in "top" and in ""
47 * but NOT in "bar.top"
51 ns_samedomain(const char *a
, const char *b
) {
59 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */
60 if (la
!= 0U && a
[la
- 1] == '.') {
62 /* Note this loop doesn't get executed if la==1. */
63 for (i
= la
- 2; i
>= 0; i
--)
75 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */
76 if (lb
!= 0U && b
[lb
- 1] == '.') {
78 /* note this loop doesn't get executed if lb==1 */
79 for (i
= lb
- 2; i
>= 0; i
--)
91 /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */
95 /* 'b' longer than 'a' means 'a' can't be in 'b'. */
99 /* 'a' and 'b' being equal at this point indicates sameness. */
101 return (strncasecmp(a
, b
, lb
) == 0);
103 /* Ok, we know la > lb. */
108 * If 'a' is only 1 character longer than 'b', then it can't be
109 * a subdomain of 'b' (because of the need for the '.' label
116 * If the character before the last 'lb' characters of 'b'
117 * isn't '.', then it can't be a match (this lets us avoid
118 * having "foobar.com" match "bar.com").
120 if (a
[diff
- 1] != '.')
124 * We're not sure about that '.', however. It could be escaped
125 * and thus not a really a label separator.
128 for (i
= diff
- 2; i
>= 0; i
--)
139 /* Now compare aligned trailing substring. */
141 return (strncasecmp(cp
, b
, lb
) == 0);
148 * is "a" a subdomain of "b"?
151 ns_subdomain(const char *a
, const char *b
) {
152 return (ns_samename(a
, b
) != 1 && ns_samedomain(a
, b
));
157 * make a canonical copy of domain name "src"
170 ns_makecanon(const char *src
, char *dst
, size_t dstsize
) {
171 size_t n
= strlen(src
);
173 if (n
+ sizeof "." > dstsize
) { /*%< Note: sizeof == 2 */
178 while (n
>= 1U && dst
[n
- 1] == '.') /*%< Ends in "." */
179 if (n
>= 2U && dst
[n
- 2] == '\\' && /*%< Ends in "\." */
180 (n
< 3U || dst
[n
- 3] != '\\')) /*%< But not "\\." */
190 * determine whether domain name "a" is the same as domain name "b"
194 *\li 0 if names differ
195 *\li 1 if names are the same
199 ns_samename(const char *a
, const char *b
) {
200 char ta
[NS_MAXDNAME
], tb
[NS_MAXDNAME
];
202 if (ns_makecanon(a
, ta
, sizeof ta
) < 0 ||
203 ns_makecanon(b
, tb
, sizeof tb
) < 0)
205 if (strcasecmp(ta
, tb
) == 0)