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b43b13ac | 1 | /* |
cd5743fd | 2 | * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") |
b43b13ac UD |
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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS | |
10 | * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES | |
11 | * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE | |
12 | * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL | |
13 | * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR | |
14 | * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS | |
15 | * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS | |
16 | * SOFTWARE. | |
17 | */ | |
18 | ||
e685e07d UD |
19 | #if !defined(_LIBC) && !defined(lint) |
20 | static const char rcsid[] = "$BINDId: ns_samedomain.c,v 8.9 1999/10/15 21:06:51 vixie Exp $"; | |
b43b13ac UD |
21 | #endif |
22 | ||
23 | #include <sys/types.h> | |
24 | #include <arpa/nameser.h> | |
25 | #include <errno.h> | |
26 | #include <string.h> | |
27 | ||
cd5743fd | 28 | /*% |
b43b13ac | 29 | * Check whether a name belongs to a domain. |
cd5743fd | 30 | * |
b43b13ac | 31 | * Inputs: |
cd5743fd UD |
32 | *\li a - the domain whose ancestory is being verified |
33 | *\li b - the potential ancestor we're checking against | |
34 | * | |
b43b13ac | 35 | * Return: |
cd5743fd UD |
36 | *\li boolean - is a at or below b? |
37 | * | |
b43b13ac | 38 | * Notes: |
cd5743fd | 39 | *\li Trailing dots are first removed from name and domain. |
b43b13ac UD |
40 | * Always compare complete subdomains, not only whether the |
41 | * domain name is the trailing string of the given name. | |
42 | * | |
cd5743fd | 43 | *\li "host.foobar.top" lies in "foobar.top" and in "top" and in "" |
b43b13ac UD |
44 | * but NOT in "bar.top" |
45 | */ | |
46 | ||
47 | int | |
48 | ns_samedomain(const char *a, const char *b) { | |
49 | size_t la, lb; | |
50 | int diff, i, escaped; | |
51 | const char *cp; | |
52 | ||
53 | la = strlen(a); | |
54 | lb = strlen(b); | |
55 | ||
56 | /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */ | |
cd5743fd | 57 | if (la != 0U && a[la - 1] == '.') { |
b43b13ac UD |
58 | escaped = 0; |
59 | /* Note this loop doesn't get executed if la==1. */ | |
60 | for (i = la - 2; i >= 0; i--) | |
61 | if (a[i] == '\\') { | |
62 | if (escaped) | |
63 | escaped = 0; | |
64 | else | |
65 | escaped = 1; | |
66 | } else | |
67 | break; | |
68 | if (!escaped) | |
69 | la--; | |
70 | } | |
71 | ||
72 | /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */ | |
cd5743fd | 73 | if (lb != 0U && b[lb - 1] == '.') { |
b43b13ac UD |
74 | escaped = 0; |
75 | /* note this loop doesn't get executed if lb==1 */ | |
76 | for (i = lb - 2; i >= 0; i--) | |
77 | if (b[i] == '\\') { | |
78 | if (escaped) | |
79 | escaped = 0; | |
80 | else | |
81 | escaped = 1; | |
82 | } else | |
83 | break; | |
84 | if (!escaped) | |
85 | lb--; | |
86 | } | |
87 | ||
88 | /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */ | |
cd5743fd | 89 | if (lb == 0U) |
b43b13ac UD |
90 | return (1); |
91 | ||
92 | /* 'b' longer than 'a' means 'a' can't be in 'b'. */ | |
93 | if (lb > la) | |
94 | return (0); | |
95 | ||
96 | /* 'a' and 'b' being equal at this point indicates sameness. */ | |
97 | if (lb == la) | |
98 | return (strncasecmp(a, b, lb) == 0); | |
99 | ||
100 | /* Ok, we know la > lb. */ | |
101 | ||
102 | diff = la - lb; | |
103 | ||
104 | /* | |
105 | * If 'a' is only 1 character longer than 'b', then it can't be | |
106 | * a subdomain of 'b' (because of the need for the '.' label | |
107 | * separator). | |
108 | */ | |
109 | if (diff < 2) | |
110 | return (0); | |
111 | ||
112 | /* | |
113 | * If the character before the last 'lb' characters of 'b' | |
114 | * isn't '.', then it can't be a match (this lets us avoid | |
115 | * having "foobar.com" match "bar.com"). | |
116 | */ | |
117 | if (a[diff - 1] != '.') | |
118 | return (0); | |
119 | ||
120 | /* | |
121 | * We're not sure about that '.', however. It could be escaped | |
122 | * and thus not a really a label separator. | |
123 | */ | |
124 | escaped = 0; | |
125 | for (i = diff - 2; i >= 0; i--) | |
cd5743fd | 126 | if (a[i] == '\\') { |
b43b13ac UD |
127 | if (escaped) |
128 | escaped = 0; | |
129 | else | |
130 | escaped = 1; | |
cd5743fd | 131 | } else |
b43b13ac UD |
132 | break; |
133 | if (escaped) | |
134 | return (0); | |
cd5743fd | 135 | |
b43b13ac UD |
136 | /* Now compare aligned trailing substring. */ |
137 | cp = a + diff; | |
138 | return (strncasecmp(cp, b, lb) == 0); | |
139 | } | |
cd5743fd | 140 | libresolv_hidden_def (ns_samedomain) |
b43b13ac | 141 | |
cd5743fd | 142 | /*% |
b43b13ac UD |
143 | * is "a" a subdomain of "b"? |
144 | */ | |
145 | int | |
146 | ns_subdomain(const char *a, const char *b) { | |
147 | return (ns_samename(a, b) != 1 && ns_samedomain(a, b)); | |
148 | } | |
149 | ||
cd5743fd | 150 | /*% |
b43b13ac | 151 | * make a canonical copy of domain name "src" |
cd5743fd | 152 | * |
b43b13ac | 153 | * notes: |
cd5743fd | 154 | * \code |
b43b13ac UD |
155 | * foo -> foo. |
156 | * foo. -> foo. | |
157 | * foo.. -> foo. | |
158 | * foo\. -> foo\.. | |
159 | * foo\\. -> foo\\. | |
cd5743fd | 160 | * \endcode |
b43b13ac UD |
161 | */ |
162 | ||
163 | int | |
164 | ns_makecanon(const char *src, char *dst, size_t dstsize) { | |
165 | size_t n = strlen(src); | |
166 | ||
cd5743fd | 167 | if (n + sizeof "." > dstsize) { /*%< Note: sizeof == 2 */ |
b43b13ac UD |
168 | __set_errno (EMSGSIZE); |
169 | return (-1); | |
170 | } | |
171 | strcpy(dst, src); | |
cd5743fd UD |
172 | while (n >= 1U && dst[n - 1] == '.') /*%< Ends in "." */ |
173 | if (n >= 2U && dst[n - 2] == '\\' && /*%< Ends in "\." */ | |
174 | (n < 3U || dst[n - 3] != '\\')) /*%< But not "\\." */ | |
b43b13ac UD |
175 | break; |
176 | else | |
177 | dst[--n] = '\0'; | |
178 | dst[n++] = '.'; | |
179 | dst[n] = '\0'; | |
180 | return (0); | |
181 | } | |
cd5743fd | 182 | libresolv_hidden_def (ns_makecanon) |
b43b13ac | 183 | |
cd5743fd | 184 | /*% |
b43b13ac | 185 | * determine whether domain name "a" is the same as domain name "b" |
cd5743fd | 186 | * |
b43b13ac | 187 | * return: |
cd5743fd UD |
188 | *\li -1 on error |
189 | *\li 0 if names differ | |
190 | *\li 1 if names are the same | |
b43b13ac UD |
191 | */ |
192 | ||
193 | int | |
194 | ns_samename(const char *a, const char *b) { | |
195 | char ta[NS_MAXDNAME], tb[NS_MAXDNAME]; | |
196 | ||
197 | if (ns_makecanon(a, ta, sizeof ta) < 0 || | |
198 | ns_makecanon(b, tb, sizeof tb) < 0) | |
199 | return (-1); | |
200 | if (strcasecmp(ta, tb) == 0) | |
201 | return (1); | |
202 | else | |
203 | return (0); | |
204 | } | |
cd5743fd UD |
205 | libresolv_hidden_def (ns_samename) |
206 | ||
207 | /*! \file */ |