2 * Copyright (c) 1995,1999 by Internet Software Consortium.
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
8 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
9 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
10 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
11 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
12 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
13 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
14 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
18 #if !defined(_LIBC) && !defined(lint)
19 static const char rcsid
[] = "$BINDId: ns_samedomain.c,v 8.9 1999/10/15 21:06:51 vixie Exp $";
22 #include <sys/types.h>
23 #include <arpa/nameser.h>
30 * Check whether a name belongs to a domain.
32 * a - the domain whose ancestory is being verified
33 * b - the potential ancestor we're checking against
35 * boolean - is a at or below b?
37 * Trailing dots are first removed from name and domain.
38 * Always compare complete subdomains, not only whether the
39 * domain name is the trailing string of the given name.
41 * "host.foobar.top" lies in "foobar.top" and in "top" and in ""
42 * but NOT in "bar.top"
46 ns_samedomain(const char *a
, const char *b
) {
54 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */
55 if (la
!= 0 && a
[la
- 1] == '.') {
57 /* Note this loop doesn't get executed if la==1. */
58 for (i
= la
- 2; i
>= 0; i
--)
70 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */
71 if (lb
!= 0 && b
[lb
- 1] == '.') {
73 /* note this loop doesn't get executed if lb==1 */
74 for (i
= lb
- 2; i
>= 0; i
--)
86 /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */
90 /* 'b' longer than 'a' means 'a' can't be in 'b'. */
94 /* 'a' and 'b' being equal at this point indicates sameness. */
96 return (strncasecmp(a
, b
, lb
) == 0);
98 /* Ok, we know la > lb. */
103 * If 'a' is only 1 character longer than 'b', then it can't be
104 * a subdomain of 'b' (because of the need for the '.' label
111 * If the character before the last 'lb' characters of 'b'
112 * isn't '.', then it can't be a match (this lets us avoid
113 * having "foobar.com" match "bar.com").
115 if (a
[diff
- 1] != '.')
119 * We're not sure about that '.', however. It could be escaped
120 * and thus not a really a label separator.
123 for (i
= diff
- 2; i
>= 0; i
--)
134 /* Now compare aligned trailing substring. */
136 return (strncasecmp(cp
, b
, lb
) == 0);
142 * is "a" a subdomain of "b"?
145 ns_subdomain(const char *a
, const char *b
) {
146 return (ns_samename(a
, b
) != 1 && ns_samedomain(a
, b
));
151 * ns_makecanon(src, dst, dstsize)
152 * make a canonical copy of domain name "src"
162 ns_makecanon(const char *src
, char *dst
, size_t dstsize
) {
163 size_t n
= strlen(src
);
165 if (n
+ sizeof "." > dstsize
) {
166 __set_errno (EMSGSIZE
);
170 while (n
> 0 && dst
[n
- 1] == '.') /* Ends in "." */
171 if (n
> 1 && dst
[n
- 2] == '\\' && /* Ends in "\." */
172 (n
< 2 || dst
[n
- 3] != '\\')) /* But not "\\." */
184 * determine whether domain name "a" is the same as domain name "b"
188 * 1 if names are the same
192 ns_samename(const char *a
, const char *b
) {
193 char ta
[NS_MAXDNAME
], tb
[NS_MAXDNAME
];
195 if (ns_makecanon(a
, ta
, sizeof ta
) < 0 ||
196 ns_makecanon(b
, tb
, sizeof tb
) < 0)
198 if (strcasecmp(ta
, tb
) == 0)