1: /*
2: * Copyright (c) 2004,2009 by Internet Systems Consortium, Inc. ("ISC")
3: * Copyright (c) 1995-2003 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: * Internet Systems Consortium, Inc.
18: * 950 Charter Street
19: * Redwood City, CA 94063
20: * <info@isc.org>
21: * https://www.isc.org/
22: */
23:
24: #ifndef lint
25: static const char rcsid[] = "$Id: ns_samedomain.c,v 1.1.1.1 2012/10/09 09:06:54 misho Exp $";
26: #endif
27:
28: #include <sys/types.h>
29: #include <errno.h>
30: #include <string.h>
31:
32: #include <netinet/in.h>
33: #include <sys/socket.h>
34:
35: #include "minires/minires.h"
36: #include "arpa/nameser.h"
37:
38: /*
39: * int
40: * ns_samedomain(a, b)
41: * Check whether a name belongs to a domain.
42: * Inputs:
43: * a - the domain whose ancestory is being verified
44: * b - the potential ancestor we're checking against
45: * Return:
46: * boolean - is a at or below b?
47: * Notes:
48: * Trailing dots are first removed from name and domain.
49: * Always compare complete subdomains, not only whether the
50: * domain name is the trailing string of the given name.
51: *
52: * "host.foobar.top" lies in "foobar.top" and in "top" and in ""
53: * but NOT in "bar.top"
54: */
55:
56: int
57: ns_samedomain(const char *a, const char *b) {
58: size_t la, lb;
59: int diff, i, escaped;
60: const char *cp;
61:
62: la = strlen(a);
63: lb = strlen(b);
64:
65: /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */
66: if (la != 0 && a[la - 1] == '.') {
67: escaped = 0;
68: /* Note this loop doesn't get executed if la==1. */
69: for (i = la - 2; i >= 0; i--)
70: if (a[i] == '\\') {
71: if (escaped)
72: escaped = 0;
73: else
74: escaped = 1;
75: } else
76: break;
77: if (!escaped)
78: la--;
79: }
80:
81: /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */
82: if (lb != 0 && b[lb - 1] == '.') {
83: escaped = 0;
84: /* note this loop doesn't get executed if lb==1 */
85: for (i = lb - 2; i >= 0; i--)
86: if (b[i] == '\\') {
87: if (escaped)
88: escaped = 0;
89: else
90: escaped = 1;
91: } else
92: break;
93: if (!escaped)
94: lb--;
95: }
96:
97: /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */
98: if (lb == 0)
99: return (1);
100:
101: /* 'b' longer than 'a' means 'a' can't be in 'b'. */
102: if (lb > la)
103: return (0);
104:
105: /* 'a' and 'b' being equal at this point indicates sameness. */
106: if (lb == la)
107: return (strncasecmp(a, b, lb) == 0);
108:
109: /* Ok, we know la > lb. */
110:
111: diff = la - lb;
112:
113: /*
114: * If 'a' is only 1 character longer than 'b', then it can't be
115: * a subdomain of 'b' (because of the need for the '.' label
116: * separator).
117: */
118: if (diff < 2)
119: return (0);
120:
121: /*
122: * If the character before the last 'lb' characters of 'b'
123: * isn't '.', then it can't be a match (this lets us avoid
124: * having "foobar.com" match "bar.com").
125: */
126: if (a[diff - 1] != '.')
127: return (0);
128:
129: /*
130: * We're not sure about that '.', however. It could be escaped
131: * and thus not a really a label separator.
132: */
133: escaped = 0;
134: for (i = diff - 2; i >= 0; i--)
135: if (a[i] == '\\') {
136: if (escaped)
137: escaped = 0;
138: else
139: escaped = 1;
140: } else
141: break;
142: if (escaped)
143: return (0);
144:
145: /* Now compare aligned trailing substring. */
146: cp = a + diff;
147: return (strncasecmp(cp, b, lb) == 0);
148: }
149:
150: /*
151: * int
152: * ns_subdomain(a, b)
153: * is "a" a subdomain of "b"?
154: */
155: int
156: ns_subdomain(const char *a, const char *b) {
157: return (ns_samename(a, b) != 1 && ns_samedomain(a, b));
158: }
159:
160: /*
161: * int
162: * ns_makecanon(src, dst, dstsize)
163: * make a canonical copy of domain name "src"
164: * notes:
165: * foo -> foo.
166: * foo. -> foo.
167: * foo.. -> foo.
168: * foo\. -> foo\..
169: * foo\\. -> foo\\.
170: */
171:
172: isc_result_t
173: ns_makecanon(const char *src, char *dst, size_t dstsize) {
174: size_t n = strlen(src);
175:
176: if (n + sizeof "." > dstsize) {
177: return ISC_R_NOSPACE;
178: }
179: strcpy(dst, src);
180: while (n > 0 && dst[n - 1] == '.') /* Ends in "." */
181: if (n > 1 && dst[n - 2] == '\\' && /* Ends in "\." */
182: (n < 2 || dst[n - 3] != '\\')) /* But not "\\." */
183: break;
184: else
185: dst[--n] = '\0';
186: dst[n++] = '.';
187: dst[n] = '\0';
188: return ISC_R_SUCCESS;
189: }
190:
191: /*
192: * int
193: * ns_samename(a, b)
194: * determine whether domain name "a" is the same as domain name "b"
195: * return:
196: * -1 on error
197: * 0 if names differ
198: * 1 if names are the same
199: */
200:
201: int
202: ns_samename(const char *a, const char *b) {
203: char ta[NS_MAXDNAME], tb[NS_MAXDNAME];
204: isc_result_t status;
205:
206: status = ns_makecanon(a, ta, sizeof ta);
207: if (status != ISC_R_SUCCESS)
208: return status;
209: status = ns_makecanon(b, tb, sizeof tb);
210: if (status != ISC_R_SUCCESS)
211: return (-1);
212: if (strcasecmp(ta, tb) == 0)
213: return (1);
214: else
215: return (0);
216: }
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