1/*
2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (c) 1995,1999 by Internet Software Consortium.
4 *
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.
8 *
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.
16 */
17
18#ifndef lint
19static const char rcsid[] = "$Id: ns_samedomain.c,v 1.1.2.2.4.2 2004/03/16 12:34:17 marka Exp $";
20#endif
21#include <sys/cdefs.h>
22__FBSDID("$FreeBSD: head/lib/libc/nameser/ns_samedomain.c 158787 2006-05-21 11:19:36Z ume $");
23
24#include "port_before.h"
25
26#include <sys/types.h>
27#include <arpa/nameser.h>
28#include <errno.h>
29#include <string.h>
30
31#include "port_after.h"
32
33/*
34 * int
35 * ns_samedomain(a, b)
36 * Check whether a name belongs to a domain.
37 * Inputs:
38 * a - the domain whose ancestory is being verified
39 * b - the potential ancestor we're checking against
40 * Return:
41 * boolean - is a at or below b?
42 * Notes:
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.
46 *
47 * "host.foobar.top" lies in "foobar.top" and in "top" and in ""
48 * but NOT in "bar.top"
49 */
50
51int
52ns_samedomain(const char *a, const char *b) {
53 size_t la, lb;
54 int diff, i, escaped;
55 const char *cp;
56
57 la = strlen(a);
58 lb = strlen(b);
59
60 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */
61 if (la != 0U && a[la - 1] == '.') {
62 escaped = 0;
63 /* Note this loop doesn't get executed if la==1. */
64 for (i = la - 2; i >= 0; i--)
65 if (a[i] == '\\') {
66 if (escaped)
67 escaped = 0;
68 else
69 escaped = 1;
70 } else
71 break;
72 if (!escaped)
73 la--;
74 }
75
76 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */
77 if (lb != 0U && b[lb - 1] == '.') {
78 escaped = 0;
79 /* note this loop doesn't get executed if lb==1 */
80 for (i = lb - 2; i >= 0; i--)
81 if (b[i] == '\\') {
82 if (escaped)
83 escaped = 0;
84 else
85 escaped = 1;
86 } else
87 break;
88 if (!escaped)
89 lb--;
90 }
91
92 /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */
93 if (lb == 0U)
94 return (1);
95
96 /* 'b' longer than 'a' means 'a' can't be in 'b'. */
97 if (lb > la)
98 return (0);
99
100 /* 'a' and 'b' being equal at this point indicates sameness. */
101 if (lb == la)
102 return (strncasecmp(a, b, lb) == 0);
103
104 /* Ok, we know la > lb. */
105
106 diff = la - lb;
107
108 /*
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
111 * separator).
112 */
113 if (diff < 2)
114 return (0);
115
116 /*
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").
120 */
121 if (a[diff - 1] != '.')
122 return (0);
123
124 /*
125 * We're not sure about that '.', however. It could be escaped
126 * and thus not a really a label separator.
127 */
128 escaped = 0;
129 for (i = diff - 2; i >= 0; i--)
130 if (a[i] == '\\') {
131 if (escaped)
132 escaped = 0;
133 else
134 escaped = 1;
135 } else
136 break;
137 if (escaped)
138 return (0);
139
140 /* Now compare aligned trailing substring. */
141 cp = a + diff;
142 return (strncasecmp(cp, b, lb) == 0);
143}
144
145#ifndef _LIBC
146/*
147 * int
148 * ns_subdomain(a, b)
149 * is "a" a subdomain of "b"?
150 */
151int
152ns_subdomain(const char *a, const char *b) {
153 return (ns_samename(a, b) != 1 && ns_samedomain(a, b));
154}
155#endif
156
157/*
158 * int
159 * ns_makecanon(src, dst, dstsize)
160 * make a canonical copy of domain name "src"
161 * notes:
162 * foo -> foo.
163 * foo. -> foo.
164 * foo.. -> foo.
165 * foo\. -> foo\..
166 * foo\\. -> foo\\.
167 */
168
169int
170ns_makecanon(const char *src, char *dst, size_t dstsize) {
171 size_t n = strlen(src);
172
173 if (n + sizeof "." > dstsize) { /* Note: sizeof == 2 */
174 errno = EMSGSIZE;
175 return (-1);
176 }
177 strcpy(dst, src);
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 "\\." */
181 break;
182 else
183 dst[--n] = '\0';
184 dst[n++] = '.';
185 dst[n] = '\0';
186 return (0);
187}
188
189/*
190 * int
191 * ns_samename(a, b)
192 * determine whether domain name "a" is the same as domain name "b"
193 * return:
194 * -1 on error
195 * 0 if names differ
196 * 1 if names are the same
197 */
198
199int
200ns_samename(const char *a, const char *b) {
201 char ta[NS_MAXDNAME], tb[NS_MAXDNAME];
202
203 if (ns_makecanon(a, ta, sizeof ta) < 0 ||
204 ns_makecanon(b, tb, sizeof tb) < 0)
205 return (-1);
206 if (strcasecmp(ta, tb) == 0)
207 return (1);
208 else
209 return (0);
210}