1 /* $NetBSD: ns_samedomain.c,v 1.1.1.1 2009/04/12 15:33:49 christos Exp $ */ 2 3 /* 4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 5 * Copyright (c) 1995,1999 by Internet Software Consortium. 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18 */ 19 20 #ifndef lint 21 static const char rcsid[] = "Id: ns_samedomain.c,v 1.6 2005/04/27 04:56:40 sra Exp"; 22 #endif 23 24 #include "port_before.h" 25 26 #include <sys/types.h> 27 #include <arpa/nameser.h> 28 #include <errno.h> 29 #include <string.h> 30 31 #include "port_after.h" 32 33 /*% 34 * Check whether a name belongs to a domain. 35 * 36 * Inputs: 37 *\li a - the domain whose ancestory is being verified 38 *\li b - the potential ancestor we're checking against 39 * 40 * Return: 41 *\li boolean - is a at or below b? 42 * 43 * Notes: 44 *\li Trailing dots are first removed from name and domain. 45 * Always compare complete subdomains, not only whether the 46 * domain name is the trailing string of the given name. 47 * 48 *\li "host.foobar.top" lies in "foobar.top" and in "top" and in "" 49 * but NOT in "bar.top" 50 */ 51 52 int 53 ns_samedomain(const char *a, const char *b) { 54 size_t la, lb; 55 int diff, i, escaped; 56 const char *cp; 57 58 la = strlen(a); 59 lb = strlen(b); 60 61 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */ 62 if (la != 0U && a[la - 1] == '.') { 63 escaped = 0; 64 /* Note this loop doesn't get executed if la==1. */ 65 for (i = la - 2; i >= 0; i--) 66 if (a[i] == '\\') { 67 if (escaped) 68 escaped = 0; 69 else 70 escaped = 1; 71 } else 72 break; 73 if (!escaped) 74 la--; 75 } 76 77 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */ 78 if (lb != 0U && b[lb - 1] == '.') { 79 escaped = 0; 80 /* note this loop doesn't get executed if lb==1 */ 81 for (i = lb - 2; i >= 0; i--) 82 if (b[i] == '\\') { 83 if (escaped) 84 escaped = 0; 85 else 86 escaped = 1; 87 } else 88 break; 89 if (!escaped) 90 lb--; 91 } 92 93 /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */ 94 if (lb == 0U) 95 return (1); 96 97 /* 'b' longer than 'a' means 'a' can't be in 'b'. */ 98 if (lb > la) 99 return (0); 100 101 /* 'a' and 'b' being equal at this point indicates sameness. */ 102 if (lb == la) 103 return (strncasecmp(a, b, lb) == 0); 104 105 /* Ok, we know la > lb. */ 106 107 diff = la - lb; 108 109 /* 110 * If 'a' is only 1 character longer than 'b', then it can't be 111 * a subdomain of 'b' (because of the need for the '.' label 112 * separator). 113 */ 114 if (diff < 2) 115 return (0); 116 117 /* 118 * If the character before the last 'lb' characters of 'b' 119 * isn't '.', then it can't be a match (this lets us avoid 120 * having "foobar.com" match "bar.com"). 121 */ 122 if (a[diff - 1] != '.') 123 return (0); 124 125 /* 126 * We're not sure about that '.', however. It could be escaped 127 * and thus not a really a label separator. 128 */ 129 escaped = 0; 130 for (i = diff - 2; i >= 0; i--) 131 if (a[i] == '\\') { 132 if (escaped) 133 escaped = 0; 134 else 135 escaped = 1; 136 } else 137 break; 138 if (escaped) 139 return (0); 140 141 /* Now compare aligned trailing substring. */ 142 cp = a + diff; 143 return (strncasecmp(cp, b, lb) == 0); 144 } 145 146 /*% 147 * is "a" a subdomain of "b"? 148 */ 149 int 150 ns_subdomain(const char *a, const char *b) { 151 return (ns_samename(a, b) != 1 && ns_samedomain(a, b)); 152 } 153 154 /*% 155 * make a canonical copy of domain name "src" 156 * 157 * notes: 158 * \code 159 * foo -> foo. 160 * foo. -> foo. 161 * foo.. -> foo. 162 * foo\. -> foo\.. 163 * foo\\. -> foo\\. 164 * \endcode 165 */ 166 167 int 168 ns_makecanon(const char *src, char *dst, size_t dstsize) { 169 size_t n = strlen(src); 170 171 if (n + sizeof "." > dstsize) { /*%< Note: sizeof == 2 */ 172 errno = EMSGSIZE; 173 return (-1); 174 } 175 strcpy(dst, src); 176 while (n >= 1U && dst[n - 1] == '.') /*%< Ends in "." */ 177 if (n >= 2U && dst[n - 2] == '\\' && /*%< Ends in "\." */ 178 (n < 3U || dst[n - 3] != '\\')) /*%< But not "\\." */ 179 break; 180 else 181 dst[--n] = '\0'; 182 dst[n++] = '.'; 183 dst[n] = '\0'; 184 return (0); 185 } 186 187 /*% 188 * determine whether domain name "a" is the same as domain name "b" 189 * 190 * return: 191 *\li -1 on error 192 *\li 0 if names differ 193 *\li 1 if names are the same 194 */ 195 196 int 197 ns_samename(const char *a, const char *b) { 198 char ta[NS_MAXDNAME], tb[NS_MAXDNAME]; 199 200 if (ns_makecanon(a, ta, sizeof ta) < 0 || 201 ns_makecanon(b, tb, sizeof tb) < 0) 202 return (-1); 203 if (strcasecmp(ta, tb) == 0) 204 return (1); 205 else 206 return (0); 207 } 208 209 /*! \file */ 210