1 /* $NetBSD: ns_samedomain.c,v 1.8 2012/11/22 20:22:31 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 1.6 2005/04/27 04:56:40 sra Exp";
24 #else
25 //__RCSID("$NetBSD: ns_samedomain.c,v 1.8 2012/11/22 20:22:31 christos Exp $");
26 #endif
27 #endif
28
29 #include "port_before.h"
30
31 #include <sys/types.h>
32 #include <arpa/nameser.h>
33 #include <errno.h>
34 #include <string.h>
35
36 #include "port_after.h"
37
38 #ifdef _LIBRESOLV
39 /*%
40 * Check whether a name belongs to a domain.
41 *
42 * Inputs:
43 *\li a - the domain whose ancestory is being verified
44 *\li b - the potential ancestor we're checking against
45 *
46 * Return:
47 *\li boolean - is a at or below b?
48 *
49 * Notes:
50 *\li Trailing dots are first removed from name and domain.
51 * Always compare complete subdomains, not only whether the
52 * domain name is the trailing string of the given name.
53 *
54 *\li "host.foobar.top" lies in "foobar.top" and in "top" and in ""
55 * but NOT in "bar.top"
56 */
57
58 int
ns_samedomain(const char * a,const char * b)59 ns_samedomain(const char *a, const char *b) {
60 size_t la, lb, i;
61 int diff, escaped;
62 const char *cp;
63
64 la = strlen(a);
65 lb = strlen(b);
66
67 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */
68 if (la != 0U && a[la - 1] == '.') {
69 escaped = 0;
70 /* Note this loop doesn't get executed if la==1. */
71 for (i = la - 1; i > 0; i--)
72 if (a[i - 1] == '\\') {
73 if (escaped)
74 escaped = 0;
75 else
76 escaped = 1;
77 } else
78 break;
79 if (!escaped)
80 la--;
81 }
82
83 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */
84 if (lb != 0U && b[lb - 1] == '.') {
85 escaped = 0;
86 /* note this loop doesn't get executed if lb==1 */
87 for (i = lb - 1; i > 0; i--)
88 if (b[i - 1] == '\\') {
89 if (escaped)
90 escaped = 0;
91 else
92 escaped = 1;
93 } else
94 break;
95 if (!escaped)
96 lb--;
97 }
98
99 /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */
100 if (lb == 0U)
101 return (1);
102
103 /* 'b' longer than 'a' means 'a' can't be in 'b'. */
104 if (lb > la)
105 return (0);
106
107 /* 'a' and 'b' being equal at this point indicates sameness. */
108 if (lb == la)
109 return (strncasecmp(a, b, lb) == 0);
110
111 /* Ok, we know la > lb. */
112
113 diff = (int)(la - lb);
114
115 /*
116 * If 'a' is only 1 character longer than 'b', then it can't be
117 * a subdomain of 'b' (because of the need for the '.' label
118 * separator).
119 */
120 if (diff < 2)
121 return (0);
122
123 /*
124 * If the character before the last 'lb' characters of 'b'
125 * isn't '.', then it can't be a match (this lets us avoid
126 * having "foobar.com" match "bar.com").
127 */
128 if (a[diff - 1] != '.')
129 return (0);
130
131 /*
132 * We're not sure about that '.', however. It could be escaped
133 * and thus not a really a label separator.
134 */
135 escaped = 0;
136 for (i = diff - 1; i > 0; i--)
137 if (a[i - 1] == '\\') {
138 if (escaped)
139 escaped = 0;
140 else
141 escaped = 1;
142 } else
143 break;
144 if (escaped)
145 return (0);
146
147 /* Now compare aligned trailing substring. */
148 cp = a + diff;
149 return (strncasecmp(cp, b, lb) == 0);
150 }
151
152 /*%
153 * is "a" a subdomain of "b"?
154 */
155 int
ns_subdomain(const char * a,const char * b)156 ns_subdomain(const char *a, const char *b) {
157 return (ns_samename(a, b) != 1 && ns_samedomain(a, b));
158 }
159 #endif
160 #define _LIBC
161 #ifdef _LIBC
162 /*%
163 * make a canonical copy of domain name "src"
164 *
165 * notes:
166 * \code
167 * foo -> foo.
168 * foo. -> foo.
169 * foo.. -> foo.
170 * foo\. -> foo\..
171 * foo\\. -> foo\\.
172 * \endcode
173 */
174
175 int
ns_makecanon(const char * src,char * dst,size_t dstsize)176 ns_makecanon(const char *src, char *dst, size_t dstsize) {
177 size_t n = strlen(src);
178
179 if (n + sizeof "." > dstsize) { /*%< Note: sizeof == 2 */
180 errno = EMSGSIZE;
181 return (-1);
182 }
183 strcpy(dst, src);
184 while (n >= 1U && dst[n - 1] == '.') /*%< Ends in "." */
185 if (n >= 2U && dst[n - 2] == '\\' && /*%< Ends in "\." */
186 (n < 3U || dst[n - 3] != '\\')) /*%< But not "\\." */
187 break;
188 else
189 dst[--n] = '\0';
190 dst[n++] = '.';
191 dst[n] = '\0';
192 return (0);
193 }
194
195 /*%
196 * determine whether domain name "a" is the same as domain name "b"
197 *
198 * return:
199 *\li -1 on error
200 *\li 0 if names differ
201 *\li 1 if names are the same
202 */
203
204 int
ns_samename(const char * a,const char * b)205 ns_samename(const char *a, const char *b) {
206 char ta[NS_MAXDNAME], tb[NS_MAXDNAME];
207
208 if (ns_makecanon(a, ta, sizeof ta) < 0 ||
209 ns_makecanon(b, tb, sizeof tb) < 0)
210 return (-1);
211 if (strcasecmp(ta, tb) == 0)
212 return (1);
213 else
214 return (0);
215 }
216 #endif
217 /*! \file */
218