]>
Commit | Line | Data |
---|---|---|
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 | ||
b43b13ac UD |
19 | #include <sys/types.h> |
20 | #include <arpa/nameser.h> | |
21 | #include <errno.h> | |
22 | #include <string.h> | |
23 | ||
cd5743fd | 24 | /*% |
b43b13ac | 25 | * Check whether a name belongs to a domain. |
cd5743fd | 26 | * |
b43b13ac | 27 | * Inputs: |
c0c3f78a | 28 | *\li a - the domain whose ancestry is being verified |
cd5743fd UD |
29 | *\li b - the potential ancestor we're checking against |
30 | * | |
b43b13ac | 31 | * Return: |
cd5743fd UD |
32 | *\li boolean - is a at or below b? |
33 | * | |
b43b13ac | 34 | * Notes: |
cd5743fd | 35 | *\li Trailing dots are first removed from name and domain. |
b43b13ac UD |
36 | * Always compare complete subdomains, not only whether the |
37 | * domain name is the trailing string of the given name. | |
38 | * | |
cd5743fd | 39 | *\li "host.foobar.top" lies in "foobar.top" and in "top" and in "" |
b43b13ac UD |
40 | * but NOT in "bar.top" |
41 | */ | |
42 | ||
43 | int | |
44 | ns_samedomain(const char *a, const char *b) { | |
45 | size_t la, lb; | |
46 | int diff, i, escaped; | |
47 | const char *cp; | |
48 | ||
49 | la = strlen(a); | |
50 | lb = strlen(b); | |
51 | ||
52 | /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */ | |
cd5743fd | 53 | if (la != 0U && a[la - 1] == '.') { |
b43b13ac UD |
54 | escaped = 0; |
55 | /* Note this loop doesn't get executed if la==1. */ | |
56 | for (i = la - 2; i >= 0; i--) | |
57 | if (a[i] == '\\') { | |
58 | if (escaped) | |
59 | escaped = 0; | |
60 | else | |
61 | escaped = 1; | |
62 | } else | |
63 | break; | |
64 | if (!escaped) | |
65 | la--; | |
66 | } | |
67 | ||
68 | /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */ | |
cd5743fd | 69 | if (lb != 0U && b[lb - 1] == '.') { |
b43b13ac UD |
70 | escaped = 0; |
71 | /* note this loop doesn't get executed if lb==1 */ | |
72 | for (i = lb - 2; i >= 0; i--) | |
73 | if (b[i] == '\\') { | |
74 | if (escaped) | |
75 | escaped = 0; | |
76 | else | |
77 | escaped = 1; | |
78 | } else | |
79 | break; | |
80 | if (!escaped) | |
81 | lb--; | |
82 | } | |
83 | ||
84 | /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */ | |
cd5743fd | 85 | if (lb == 0U) |
b43b13ac UD |
86 | return (1); |
87 | ||
88 | /* 'b' longer than 'a' means 'a' can't be in 'b'. */ | |
89 | if (lb > la) | |
90 | return (0); | |
91 | ||
92 | /* 'a' and 'b' being equal at this point indicates sameness. */ | |
93 | if (lb == la) | |
94 | return (strncasecmp(a, b, lb) == 0); | |
95 | ||
96 | /* Ok, we know la > lb. */ | |
97 | ||
98 | diff = la - lb; | |
99 | ||
100 | /* | |
101 | * If 'a' is only 1 character longer than 'b', then it can't be | |
102 | * a subdomain of 'b' (because of the need for the '.' label | |
103 | * separator). | |
104 | */ | |
105 | if (diff < 2) | |
106 | return (0); | |
107 | ||
108 | /* | |
109 | * If the character before the last 'lb' characters of 'b' | |
110 | * isn't '.', then it can't be a match (this lets us avoid | |
111 | * having "foobar.com" match "bar.com"). | |
112 | */ | |
113 | if (a[diff - 1] != '.') | |
114 | return (0); | |
115 | ||
116 | /* | |
117 | * We're not sure about that '.', however. It could be escaped | |
118 | * and thus not a really a label separator. | |
119 | */ | |
120 | escaped = 0; | |
121 | for (i = diff - 2; i >= 0; i--) | |
cd5743fd | 122 | if (a[i] == '\\') { |
b43b13ac UD |
123 | if (escaped) |
124 | escaped = 0; | |
125 | else | |
126 | escaped = 1; | |
cd5743fd | 127 | } else |
b43b13ac UD |
128 | break; |
129 | if (escaped) | |
130 | return (0); | |
cd5743fd | 131 | |
b43b13ac UD |
132 | /* Now compare aligned trailing substring. */ |
133 | cp = a + diff; | |
134 | return (strncasecmp(cp, b, lb) == 0); | |
135 | } | |
cd5743fd | 136 | libresolv_hidden_def (ns_samedomain) |
b43b13ac | 137 | |
cd5743fd | 138 | /*% |
b43b13ac UD |
139 | * is "a" a subdomain of "b"? |
140 | */ | |
141 | int | |
142 | ns_subdomain(const char *a, const char *b) { | |
143 | return (ns_samename(a, b) != 1 && ns_samedomain(a, b)); | |
144 | } | |
145 | ||
cd5743fd | 146 | /*% |
b43b13ac | 147 | * make a canonical copy of domain name "src" |
cd5743fd | 148 | * |
b43b13ac | 149 | * notes: |
cd5743fd | 150 | * \code |
b43b13ac UD |
151 | * foo -> foo. |
152 | * foo. -> foo. | |
153 | * foo.. -> foo. | |
154 | * foo\. -> foo\.. | |
155 | * foo\\. -> foo\\. | |
cd5743fd | 156 | * \endcode |
b43b13ac UD |
157 | */ |
158 | ||
159 | int | |
160 | ns_makecanon(const char *src, char *dst, size_t dstsize) { | |
161 | size_t n = strlen(src); | |
162 | ||
cd5743fd | 163 | if (n + sizeof "." > dstsize) { /*%< Note: sizeof == 2 */ |
b43b13ac UD |
164 | __set_errno (EMSGSIZE); |
165 | return (-1); | |
166 | } | |
167 | strcpy(dst, src); | |
cd5743fd UD |
168 | while (n >= 1U && dst[n - 1] == '.') /*%< Ends in "." */ |
169 | if (n >= 2U && dst[n - 2] == '\\' && /*%< Ends in "\." */ | |
170 | (n < 3U || dst[n - 3] != '\\')) /*%< But not "\\." */ | |
b43b13ac UD |
171 | break; |
172 | else | |
173 | dst[--n] = '\0'; | |
174 | dst[n++] = '.'; | |
175 | dst[n] = '\0'; | |
176 | return (0); | |
177 | } | |
cd5743fd | 178 | libresolv_hidden_def (ns_makecanon) |
b43b13ac | 179 | |
cd5743fd | 180 | /*% |
b43b13ac | 181 | * determine whether domain name "a" is the same as domain name "b" |
cd5743fd | 182 | * |
b43b13ac | 183 | * return: |
cd5743fd UD |
184 | *\li -1 on error |
185 | *\li 0 if names differ | |
186 | *\li 1 if names are the same | |
b43b13ac UD |
187 | */ |
188 | ||
189 | int | |
190 | ns_samename(const char *a, const char *b) { | |
191 | char ta[NS_MAXDNAME], tb[NS_MAXDNAME]; | |
192 | ||
193 | if (ns_makecanon(a, ta, sizeof ta) < 0 || | |
194 | ns_makecanon(b, tb, sizeof tb) < 0) | |
195 | return (-1); | |
196 | if (strcasecmp(ta, tb) == 0) | |
197 | return (1); | |
198 | else | |
199 | return (0); | |
200 | } | |
cd5743fd UD |
201 | libresolv_hidden_def (ns_samename) |
202 | ||
203 | /*! \file */ |