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 1.1.2.2.4.2 2004/03/16 12:34:17 marka Exp $";
21 #include <sys/cdefs.h>
22 __FBSDID("$FreeBSD$");
24 #include "port_before.h"
26 #include <sys/types.h>
27 #include <arpa/nameser.h>
31 #include "port_after.h"
36 * Check whether a name belongs to a domain.
38 * a - the domain whose ancestory is being verified
39 * b - the potential ancestor we're checking against
41 * boolean - is a at or below b?
43 * Trailing dots are first removed from name and domain.
44 * Always compare complete subdomains, not only whether the
45 * domain name is the trailing string of the given name.
47 * "host.foobar.top" lies in "foobar.top" and in "top" and in ""
48 * but NOT in "bar.top"
52 ns_samedomain(const char *a, const char *b) {
60 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */
61 if (la != 0U && a[la - 1] == '.') {
63 /* Note this loop doesn't get executed if la==1. */
64 for (i = la - 2; i >= 0; i--)
76 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */
77 if (lb != 0U && b[lb - 1] == '.') {
79 /* note this loop doesn't get executed if lb==1 */
80 for (i = lb - 2; i >= 0; i--)
92 /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */
96 /* 'b' longer than 'a' means 'a' can't be in 'b'. */
100 /* 'a' and 'b' being equal at this point indicates sameness. */
102 return (strncasecmp(a, b, lb) == 0);
104 /* Ok, we know la > lb. */
109 * If 'a' is only 1 character longer than 'b', then it can't be
110 * a subdomain of 'b' (because of the need for the '.' label
117 * If the character before the last 'lb' characters of 'b'
118 * isn't '.', then it can't be a match (this lets us avoid
119 * having "foobar.com" match "bar.com").
121 if (a[diff - 1] != '.')
125 * We're not sure about that '.', however. It could be escaped
126 * and thus not a really a label separator.
129 for (i = diff - 2; i >= 0; i--)
140 /* Now compare aligned trailing substring. */
142 return (strncasecmp(cp, b, lb) == 0);
149 * is "a" a subdomain of "b"?
152 ns_subdomain(const char *a, const char *b) {
153 return (ns_samename(a, b) != 1 && ns_samedomain(a, b));
159 * ns_makecanon(src, dst, dstsize)
160 * 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 "\\." */
192 * determine whether domain name "a" is the same as domain name "b"
196 * 1 if names are the same
200 ns_samename(const char *a, const char *b) {
201 char ta[NS_MAXDNAME], tb[NS_MAXDNAME];
203 if (ns_makecanon(a, ta, sizeof ta) < 0 ||
204 ns_makecanon(b, tb, sizeof tb) < 0)
206 if (strcasecmp(ta, tb) == 0)