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.
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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
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14 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
19 static const char rcsid[] = "$Id: ns_samedomain.c,v 1.3 2001/01/16 22:33:09 mellon Exp $";
22 #include <sys/types.h>
26 #include <netinet/in.h>
27 #include <sys/socket.h>
29 #include "minires/minires.h"
30 #include "arpa/nameser.h"
35 * Check whether a name belongs to a domain.
37 * a - the domain whose ancestory is being verified
38 * b - the potential ancestor we're checking against
40 * boolean - is a at or below b?
42 * 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 * "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 != 0 && 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 != 0 && 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);
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));
156 * ns_makecanon(src, dst, dstsize)
157 * make a canonical copy of domain name "src"
167 ns_makecanon(const char *src, char *dst, size_t dstsize) {
168 size_t n = strlen(src);
170 if (n + sizeof "." > dstsize) {
174 while (n > 0 && dst[n - 1] == '.') /* Ends in "." */
175 if (n > 1 && dst[n - 2] == '\\' && /* Ends in "\." */
176 (n < 2 || dst[n - 3] != '\\')) /* But not "\\." */
182 return ISC_R_SUCCESS;
188 * determine whether domain name "a" is the same as domain name "b"
192 * 1 if names are the same
196 ns_samename(const char *a, const char *b) {
197 char ta[NS_MAXDNAME], tb[NS_MAXDNAME];
200 status = ns_makecanon(a, ta, sizeof ta);
201 if (status != ISC_R_SUCCESS)
203 status = ns_makecanon(b, tb, sizeof tb);
204 if (status != ISC_R_SUCCESS)
206 if (strcasecmp(ta, tb) == 0)