1 /* $NetBSD: ns_samedomain.c,v 1.2 2004/05/20 20:35:05 christos Exp $ */
2
3 /*
4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
5 * Copyright (c) 1995,1999 by Internet Software Consortium.
6 *
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.
10 *
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.
18 */
19
20 #include <sys/cdefs.h>
21 #ifndef lint
22 #ifdef notdef
23 static const char rcsid[] = "Id: ns_samedomain.c,v 1.1.2.2.4.2 2004/03/16 12:34:17 marka Exp";
24 #else
25 __RCSID("$NetBSD: ns_samedomain.c,v 1.2 2004/05/20 20:35:05 christos Exp $");
26 #endif
27 #endif
28
29 #include <sys/types.h>
30 #include "arpa_nameser.h"
31 #include <errno.h>
32 #include <string.h>
33
34 #ifndef _LIBC
35 /*
36 * int
37 * ns_samedomain(a, b)
38 * Check whether a name belongs to a domain.
39 * Inputs:
40 * a - the domain whose ancestory is being verified
41 * b - the potential ancestor we're checking against
42 * Return:
43 * boolean - is a at or below b?
44 * Notes:
45 * Trailing dots are first removed from name and domain.
46 * Always compare complete subdomains, not only whether the
47 * domain name is the trailing string of the given name.
48 *
49 * "host.foobar.top" lies in "foobar.top" and in "top" and in ""
50 * but NOT in "bar.top"
51 */
52
53 int
ns_samedomain(const char * a,const char * b)54 ns_samedomain(const char *a, const char *b) {
55 size_t la, lb;
56 int diff, i, escaped;
57 const char *cp;
58
59 la = strlen(a);
60 lb = strlen(b);
61
62 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */
63 if (la != 0U && a[la - 1] == '.') {
64 escaped = 0;
65 /* Note this loop doesn't get executed if la==1. */
66 for (i = la - 2; i >= 0; i--)
67 if (a[i] == '\\') {
68 if (escaped)
69 escaped = 0;
70 else
71 escaped = 1;
72 } else
73 break;
74 if (!escaped)
75 la--;
76 }
77
78 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */
79 if (lb != 0U && b[lb - 1] == '.') {
80 escaped = 0;
81 /* note this loop doesn't get executed if lb==1 */
82 for (i = lb - 2; i >= 0; i--)
83 if (b[i] == '\\') {
84 if (escaped)
85 escaped = 0;
86 else
87 escaped = 1;
88 } else
89 break;
90 if (!escaped)
91 lb--;
92 }
93
94 /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */
95 if (lb == 0U)
96 return (1);
97
98 /* 'b' longer than 'a' means 'a' can't be in 'b'. */
99 if (lb > la)
100 return (0);
101
102 /* 'a' and 'b' being equal at this point indicates sameness. */
103 if (lb == la)
104 return (strncasecmp(a, b, lb) == 0);
105
106 /* Ok, we know la > lb. */
107
108 diff = la - lb;
109
110 /*
111 * If 'a' is only 1 character longer than 'b', then it can't be
112 * a subdomain of 'b' (because of the need for the '.' label
113 * separator).
114 */
115 if (diff < 2)
116 return (0);
117
118 /*
119 * If the character before the last 'lb' characters of 'b'
120 * isn't '.', then it can't be a match (this lets us avoid
121 * having "foobar.com" match "bar.com").
122 */
123 if (a[diff - 1] != '.')
124 return (0);
125
126 /*
127 * We're not sure about that '.', however. It could be escaped
128 * and thus not a really a label separator.
129 */
130 escaped = 0;
131 for (i = diff - 2; i >= 0; i--)
132 if (a[i] == '\\') {
133 if (escaped)
134 escaped = 0;
135 else
136 escaped = 1;
137 } else
138 break;
139 if (escaped)
140 return (0);
141
142 /* Now compare aligned trailing substring. */
143 cp = a + diff;
144 return (strncasecmp(cp, b, lb) == 0);
145 }
146
147 /*
148 * int
149 * ns_subdomain(a, b)
150 * is "a" a subdomain of "b"?
151 */
152 int
ns_subdomain(const char * a,const char * b)153 ns_subdomain(const char *a, const char *b) {
154 return (ns_samename(a, b) != 1 && ns_samedomain(a, b));
155 }
156 #endif
157
158 /*
159 * int
160 * ns_makecanon(src, dst, dstsize)
161 * make a canonical copy of domain name "src"
162 * notes:
163 * foo -> foo.
164 * foo. -> foo.
165 * foo.. -> foo.
166 * foo\. -> foo\..
167 * foo\\. -> foo\\.
168 */
169
170 int
ns_makecanon(const char * src,char * dst,size_t dstsize)171 ns_makecanon(const char *src, char *dst, size_t dstsize) {
172 size_t n = strlen(src);
173
174 if (n + sizeof "." > dstsize) { /* Note: sizeof == 2 */
175 errno = EMSGSIZE;
176 return (-1);
177 }
178 strcpy(dst, src);
179 while (n >= 1U && dst[n - 1] == '.') /* Ends in "." */
180 if (n >= 2U && dst[n - 2] == '\\' && /* Ends in "\." */
181 (n < 3U || dst[n - 3] != '\\')) /* But not "\\." */
182 break;
183 else
184 dst[--n] = '\0';
185 dst[n++] = '.';
186 dst[n] = '\0';
187 return (0);
188 }
189
190 /*
191 * int
192 * ns_samename(a, b)
193 * determine whether domain name "a" is the same as domain name "b"
194 * return:
195 * -1 on error
196 * 0 if names differ
197 * 1 if names are the same
198 */
199
200 int
ns_samename(const char * a,const char * b)201 ns_samename(const char *a, const char *b) {
202 char ta[NS_MAXDNAME], tb[NS_MAXDNAME];
203
204 if (ns_makecanon(a, ta, sizeof ta) < 0 ||
205 ns_makecanon(b, tb, sizeof tb) < 0)
206 return (-1);
207 if (strcasecmp(ta, tb) == 0)
208 return (1);
209 else
210 return (0);
211 }
212