[0d928a0] | 1 | /* |
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| 2 | * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") |
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| 3 | * Copyright (c) 1995,1999 by Internet Software Consortium. |
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| 4 | * |
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| 5 | * Permission to use, copy, modify, and distribute this software for any |
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| 6 | * purpose with or without fee is hereby granted, provided that the above |
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| 7 | * copyright notice and this permission notice appear in all copies. |
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| 8 | * |
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| 9 | * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES |
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| 10 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
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| 11 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR |
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| 12 | * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
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| 13 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
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| 14 | * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT |
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| 15 | * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
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| 16 | */ |
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| 17 | |
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| 18 | #ifndef lint |
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| 19 | static const char rcsid[] = "$Id: ns_samedomain.c,v 1.5.18.1 2005/04/27 05:01:09 sra Exp $"; |
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| 20 | #endif |
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| 21 | #include <sys/cdefs.h> |
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| 22 | __FBSDID("$FreeBSD$"); |
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| 23 | |
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| 24 | #include "port_before.h" |
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| 25 | |
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| 26 | #include <sys/types.h> |
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| 27 | #include <arpa/nameser.h> |
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| 28 | #include <errno.h> |
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| 29 | #include <string.h> |
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| 30 | |
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| 31 | #include "port_after.h" |
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| 32 | |
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| 33 | /*% |
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| 34 | * Check whether a name belongs to a domain. |
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| 35 | * |
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| 36 | * Inputs: |
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| 37 | *\li a - the domain whose ancestory is being verified |
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| 38 | *\li b - the potential ancestor we're checking against |
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| 39 | * |
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| 40 | * Return: |
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| 41 | *\li boolean - is a at or below b? |
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| 42 | * |
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| 43 | * Notes: |
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| 44 | *\li Trailing dots are first removed from name and domain. |
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| 45 | * Always compare complete subdomains, not only whether the |
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| 46 | * domain name is the trailing string of the given name. |
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| 47 | * |
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| 48 | *\li "host.foobar.top" lies in "foobar.top" and in "top" and in "" |
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| 49 | * but NOT in "bar.top" |
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| 50 | */ |
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| 51 | |
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| 52 | int |
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| 53 | ns_samedomain(const char *a, const char *b) { |
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| 54 | size_t la, lb; |
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| 55 | int diff, i, escaped; |
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| 56 | const char *cp; |
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| 57 | |
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| 58 | la = strlen(a); |
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| 59 | lb = strlen(b); |
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| 60 | |
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| 61 | /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */ |
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| 62 | if (la != 0U && a[la - 1] == '.') { |
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| 63 | escaped = 0; |
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| 64 | /* Note this loop doesn't get executed if la==1. */ |
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| 65 | for (i = la - 2; i >= 0; i--) |
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| 66 | if (a[i] == '\\') { |
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| 67 | if (escaped) |
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| 68 | escaped = 0; |
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| 69 | else |
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| 70 | escaped = 1; |
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| 71 | } else |
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| 72 | break; |
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| 73 | if (!escaped) |
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| 74 | la--; |
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| 75 | } |
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| 76 | |
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| 77 | /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */ |
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| 78 | if (lb != 0U && b[lb - 1] == '.') { |
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| 79 | escaped = 0; |
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| 80 | /* note this loop doesn't get executed if lb==1 */ |
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| 81 | for (i = lb - 2; i >= 0; i--) |
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| 82 | if (b[i] == '\\') { |
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| 83 | if (escaped) |
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| 84 | escaped = 0; |
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| 85 | else |
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| 86 | escaped = 1; |
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| 87 | } else |
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| 88 | break; |
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| 89 | if (!escaped) |
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| 90 | lb--; |
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| 91 | } |
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| 92 | |
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| 93 | /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */ |
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| 94 | if (lb == 0U) |
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| 95 | return (1); |
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| 96 | |
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| 97 | /* 'b' longer than 'a' means 'a' can't be in 'b'. */ |
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| 98 | if (lb > la) |
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| 99 | return (0); |
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| 100 | |
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| 101 | /* 'a' and 'b' being equal at this point indicates sameness. */ |
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| 102 | if (lb == la) |
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| 103 | return (strncasecmp(a, b, lb) == 0); |
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| 104 | |
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| 105 | /* Ok, we know la > lb. */ |
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| 106 | |
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| 107 | diff = la - lb; |
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| 108 | |
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| 109 | /* |
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| 110 | * If 'a' is only 1 character longer than 'b', then it can't be |
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| 111 | * a subdomain of 'b' (because of the need for the '.' label |
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| 112 | * separator). |
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| 113 | */ |
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| 114 | if (diff < 2) |
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| 115 | return (0); |
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| 116 | |
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| 117 | /* |
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| 118 | * If the character before the last 'lb' characters of 'b' |
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| 119 | * isn't '.', then it can't be a match (this lets us avoid |
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| 120 | * having "foobar.com" match "bar.com"). |
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| 121 | */ |
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| 122 | if (a[diff - 1] != '.') |
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| 123 | return (0); |
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| 124 | |
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| 125 | /* |
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| 126 | * We're not sure about that '.', however. It could be escaped |
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| 127 | * and thus not a really a label separator. |
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| 128 | */ |
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| 129 | escaped = 0; |
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| 130 | for (i = diff - 2; i >= 0; i--) |
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| 131 | if (a[i] == '\\') { |
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| 132 | if (escaped) |
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| 133 | escaped = 0; |
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| 134 | else |
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| 135 | escaped = 1; |
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| 136 | } else |
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| 137 | break; |
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| 138 | if (escaped) |
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| 139 | return (0); |
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| 140 | |
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| 141 | /* Now compare aligned trailing substring. */ |
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| 142 | cp = a + diff; |
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| 143 | return (strncasecmp(cp, b, lb) == 0); |
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| 144 | } |
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| 145 | |
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| 146 | #ifndef _LIBC |
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| 147 | /*% |
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| 148 | * is "a" a subdomain of "b"? |
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| 149 | */ |
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| 150 | int |
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| 151 | ns_subdomain(const char *a, const char *b) { |
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| 152 | return (ns_samename(a, b) != 1 && ns_samedomain(a, b)); |
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| 153 | } |
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| 154 | #endif |
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| 155 | |
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| 156 | /*% |
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| 157 | * make a canonical copy of domain name "src" |
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| 158 | * |
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| 159 | * notes: |
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| 160 | * \code |
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| 161 | * foo -> foo. |
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| 162 | * foo. -> foo. |
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| 163 | * foo.. -> foo. |
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| 164 | * foo\. -> foo\.. |
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| 165 | * foo\\. -> foo\\. |
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| 166 | * \endcode |
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| 167 | */ |
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| 168 | |
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| 169 | int |
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| 170 | ns_makecanon(const char *src, char *dst, size_t dstsize) { |
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| 171 | size_t n = strlen(src); |
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| 172 | |
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| 173 | if (n + sizeof "." > dstsize) { /*%< Note: sizeof == 2 */ |
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| 174 | errno = EMSGSIZE; |
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| 175 | return (-1); |
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| 176 | } |
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| 177 | strcpy(dst, src); |
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| 178 | while (n >= 1U && dst[n - 1] == '.') /*%< Ends in "." */ |
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| 179 | if (n >= 2U && dst[n - 2] == '\\' && /*%< Ends in "\." */ |
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| 180 | (n < 3U || dst[n - 3] != '\\')) /*%< But not "\\." */ |
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| 181 | break; |
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| 182 | else |
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| 183 | dst[--n] = '\0'; |
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| 184 | dst[n++] = '.'; |
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| 185 | dst[n] = '\0'; |
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| 186 | return (0); |
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| 187 | } |
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| 188 | |
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| 189 | /*% |
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| 190 | * determine whether domain name "a" is the same as domain name "b" |
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| 191 | * |
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| 192 | * return: |
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| 193 | *\li -1 on error |
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| 194 | *\li 0 if names differ |
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| 195 | *\li 1 if names are the same |
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| 196 | */ |
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| 197 | |
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| 198 | int |
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| 199 | ns_samename(const char *a, const char *b) { |
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| 200 | char ta[NS_MAXDNAME], tb[NS_MAXDNAME]; |
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| 201 | |
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| 202 | if (ns_makecanon(a, ta, sizeof ta) < 0 || |
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| 203 | ns_makecanon(b, tb, sizeof tb) < 0) |
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| 204 | return (-1); |
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| 205 | if (strcasecmp(ta, tb) == 0) |
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| 206 | return (1); |
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| 207 | else |
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| 208 | return (0); |
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| 209 | } |
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| 210 | |
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| 211 | /*! \file */ |
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