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b43b13ac UD |
1 | /* |
2 | * Copyright (c) 1995,1999 by Internet Software Consortium. | |
3 | * | |
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. | |
7 | * | |
8 | * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS | |
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 | |
12 | * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR | |
13 | * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS | |
14 | * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS | |
15 | * SOFTWARE. | |
16 | */ | |
17 | ||
e685e07d UD |
18 | #if !defined(_LIBC) && !defined(lint) |
19 | static const char rcsid[] = "$BINDId: ns_samedomain.c,v 8.9 1999/10/15 21:06:51 vixie Exp $"; | |
b43b13ac UD |
20 | #endif |
21 | ||
22 | #include <sys/types.h> | |
23 | #include <arpa/nameser.h> | |
24 | #include <errno.h> | |
25 | #include <string.h> | |
26 | ||
27 | /* | |
28 | * int | |
29 | * ns_samedomain(a, b) | |
30 | * Check whether a name belongs to a domain. | |
31 | * Inputs: | |
32 | * a - the domain whose ancestory is being verified | |
33 | * b - the potential ancestor we're checking against | |
34 | * Return: | |
35 | * boolean - is a at or below b? | |
36 | * Notes: | |
37 | * Trailing dots are first removed from name and domain. | |
38 | * Always compare complete subdomains, not only whether the | |
39 | * domain name is the trailing string of the given name. | |
40 | * | |
41 | * "host.foobar.top" lies in "foobar.top" and in "top" and in "" | |
42 | * but NOT in "bar.top" | |
43 | */ | |
44 | ||
45 | int | |
46 | ns_samedomain(const char *a, const char *b) { | |
47 | size_t la, lb; | |
48 | int diff, i, escaped; | |
49 | const char *cp; | |
50 | ||
51 | la = strlen(a); | |
52 | lb = strlen(b); | |
53 | ||
54 | /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */ | |
55 | if (la != 0 && a[la - 1] == '.') { | |
56 | escaped = 0; | |
57 | /* Note this loop doesn't get executed if la==1. */ | |
58 | for (i = la - 2; i >= 0; i--) | |
59 | if (a[i] == '\\') { | |
60 | if (escaped) | |
61 | escaped = 0; | |
62 | else | |
63 | escaped = 1; | |
64 | } else | |
65 | break; | |
66 | if (!escaped) | |
67 | la--; | |
68 | } | |
69 | ||
70 | /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */ | |
71 | if (lb != 0 && b[lb - 1] == '.') { | |
72 | escaped = 0; | |
73 | /* note this loop doesn't get executed if lb==1 */ | |
74 | for (i = lb - 2; i >= 0; i--) | |
75 | if (b[i] == '\\') { | |
76 | if (escaped) | |
77 | escaped = 0; | |
78 | else | |
79 | escaped = 1; | |
80 | } else | |
81 | break; | |
82 | if (!escaped) | |
83 | lb--; | |
84 | } | |
85 | ||
86 | /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */ | |
87 | if (lb == 0) | |
88 | return (1); | |
89 | ||
90 | /* 'b' longer than 'a' means 'a' can't be in 'b'. */ | |
91 | if (lb > la) | |
92 | return (0); | |
93 | ||
94 | /* 'a' and 'b' being equal at this point indicates sameness. */ | |
95 | if (lb == la) | |
96 | return (strncasecmp(a, b, lb) == 0); | |
97 | ||
98 | /* Ok, we know la > lb. */ | |
99 | ||
100 | diff = la - lb; | |
101 | ||
102 | /* | |
103 | * If 'a' is only 1 character longer than 'b', then it can't be | |
104 | * a subdomain of 'b' (because of the need for the '.' label | |
105 | * separator). | |
106 | */ | |
107 | if (diff < 2) | |
108 | return (0); | |
109 | ||
110 | /* | |
111 | * If the character before the last 'lb' characters of 'b' | |
112 | * isn't '.', then it can't be a match (this lets us avoid | |
113 | * having "foobar.com" match "bar.com"). | |
114 | */ | |
115 | if (a[diff - 1] != '.') | |
116 | return (0); | |
117 | ||
118 | /* | |
119 | * We're not sure about that '.', however. It could be escaped | |
120 | * and thus not a really a label separator. | |
121 | */ | |
122 | escaped = 0; | |
123 | for (i = diff - 2; i >= 0; i--) | |
124 | if (a[i] == '\\') | |
125 | if (escaped) | |
126 | escaped = 0; | |
127 | else | |
128 | escaped = 1; | |
129 | else | |
130 | break; | |
131 | if (escaped) | |
132 | return (0); | |
133 | ||
134 | /* Now compare aligned trailing substring. */ | |
135 | cp = a + diff; | |
136 | return (strncasecmp(cp, b, lb) == 0); | |
137 | } | |
138 | ||
139 | /* | |
140 | * int | |
141 | * ns_subdomain(a, b) | |
142 | * is "a" a subdomain of "b"? | |
143 | */ | |
144 | int | |
145 | ns_subdomain(const char *a, const char *b) { | |
146 | return (ns_samename(a, b) != 1 && ns_samedomain(a, b)); | |
147 | } | |
148 | ||
149 | /* | |
150 | * int | |
151 | * ns_makecanon(src, dst, dstsize) | |
152 | * make a canonical copy of domain name "src" | |
153 | * notes: | |
154 | * foo -> foo. | |
155 | * foo. -> foo. | |
156 | * foo.. -> foo. | |
157 | * foo\. -> foo\.. | |
158 | * foo\\. -> foo\\. | |
159 | */ | |
160 | ||
161 | int | |
162 | ns_makecanon(const char *src, char *dst, size_t dstsize) { | |
163 | size_t n = strlen(src); | |
164 | ||
165 | if (n + sizeof "." > dstsize) { | |
166 | __set_errno (EMSGSIZE); | |
167 | return (-1); | |
168 | } | |
169 | strcpy(dst, src); | |
170 | while (n > 0 && dst[n - 1] == '.') /* Ends in "." */ | |
171 | if (n > 1 && dst[n - 2] == '\\' && /* Ends in "\." */ | |
172 | (n < 2 || dst[n - 3] != '\\')) /* But not "\\." */ | |
173 | break; | |
174 | else | |
175 | dst[--n] = '\0'; | |
176 | dst[n++] = '.'; | |
177 | dst[n] = '\0'; | |
178 | return (0); | |
179 | } | |
180 | ||
181 | /* | |
182 | * int | |
183 | * ns_samename(a, b) | |
184 | * determine whether domain name "a" is the same as domain name "b" | |
185 | * return: | |
186 | * -1 on error | |
187 | * 0 if names differ | |
188 | * 1 if names are the same | |
189 | */ | |
190 | ||
191 | int | |
192 | ns_samename(const char *a, const char *b) { | |
193 | char ta[NS_MAXDNAME], tb[NS_MAXDNAME]; | |
194 | ||
195 | if (ns_makecanon(a, ta, sizeof ta) < 0 || | |
196 | ns_makecanon(b, tb, sizeof tb) < 0) | |
197 | return (-1); | |
198 | if (strcasecmp(ta, tb) == 0) | |
199 | return (1); | |
200 | else | |
201 | return (0); | |
202 | } |