1 /* 2 * Copyright 2003 Sun Microsystems, Inc. All rights reserved. 3 * Use is subject to license terms. 4 */ 5 6 #pragma ident "%Z%%M% %I% %E% SMI" 7 8 /* 9 * Copyright (c) 1995,1999 by Internet Software Consortium. 10 * 11 * Permission to use, copy, modify, and distribute this software for any 12 * purpose with or without fee is hereby granted, provided that the above 13 * copyright notice and this permission notice appear in all copies. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS 16 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE 18 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 19 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 20 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 21 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 22 * SOFTWARE. 23 */ 24 25 #ifndef lint 26 static const char rcsid[] = "$Id: ns_samedomain.c,v 8.11 2003/04/14 14:52:48 vixie Exp $"; 27 #endif 28 29 #include "port_before.h" 30 31 #include <sys/types.h> 32 #include <arpa/nameser.h> 33 #include <errno.h> 34 #include <string.h> 35 36 #include "port_after.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 int 173 ns_makecanon(const char *src, char *dst, size_t dstsize) { 174 size_t n = strlen(src); 175 176 if (n + sizeof "." > dstsize) { /* Note: sizeof == 2 */ 177 errno = EMSGSIZE; 178 return (-1); 179 } 180 strcpy(dst, src); 181 while (n >= 1 && dst[n - 1] == '.') /* Ends in "." */ 182 if (n >= 2 && dst[n - 2] == '\\' && /* Ends in "\." */ 183 (n < 3 || dst[n - 3] != '\\')) /* But not "\\." */ 184 break; 185 else 186 dst[--n] = '\0'; 187 dst[n++] = '.'; 188 dst[n] = '\0'; 189 return (0); 190 } 191 192 /* 193 * int 194 * ns_samename(a, b) 195 * determine whether domain name "a" is the same as domain name "b" 196 * return: 197 * -1 on error 198 * 0 if names differ 199 * 1 if names are the same 200 */ 201 202 int 203 ns_samename(const char *a, const char *b) { 204 char ta[NS_MAXDNAME], tb[NS_MAXDNAME]; 205 206 if (ns_makecanon(a, ta, sizeof ta) < 0 || 207 ns_makecanon(b, tb, sizeof tb) < 0) 208 return (-1); 209 if (strcasecmp(ta, tb) == 0) 210 return (1); 211 else 212 return (0); 213 } 214