1 /* $NetBSD: ns_samedomain.c,v 1.2 2004/05/20 20:35:05 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 #include <sys/cdefs.h> 21 #ifndef lint 22 #ifdef notdef 23 static const char rcsid[] = "Id: ns_samedomain.c,v 1.1.2.2.4.2 2004/03/16 12:34:17 marka Exp"; 24 #else 25 __RCSID("$NetBSD: ns_samedomain.c,v 1.2 2004/05/20 20:35:05 christos Exp $"); 26 #endif 27 #endif 28 29 #include <sys/types.h> 30 #include "arpa_nameser.h" 31 #include <errno.h> 32 #include <string.h> 33 34 #ifndef _LIBC 35 /* 36 * int 37 * ns_samedomain(a, b) 38 * Check whether a name belongs to a domain. 39 * Inputs: 40 * a - the domain whose ancestory is being verified 41 * b - the potential ancestor we're checking against 42 * Return: 43 * boolean - is a at or below b? 44 * Notes: 45 * Trailing dots are first removed from name and domain. 46 * Always compare complete subdomains, not only whether the 47 * domain name is the trailing string of the given name. 48 * 49 * "host.foobar.top" lies in "foobar.top" and in "top" and in "" 50 * but NOT in "bar.top" 51 */ 52 53 int 54 ns_samedomain(const char *a, const char *b) { 55 size_t la, lb; 56 int diff, i, escaped; 57 const char *cp; 58 59 la = strlen(a); 60 lb = strlen(b); 61 62 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */ 63 if (la != 0U && a[la - 1] == '.') { 64 escaped = 0; 65 /* Note this loop doesn't get executed if la==1. */ 66 for (i = la - 2; i >= 0; i--) 67 if (a[i] == '\\') { 68 if (escaped) 69 escaped = 0; 70 else 71 escaped = 1; 72 } else 73 break; 74 if (!escaped) 75 la--; 76 } 77 78 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */ 79 if (lb != 0U && b[lb - 1] == '.') { 80 escaped = 0; 81 /* note this loop doesn't get executed if lb==1 */ 82 for (i = lb - 2; i >= 0; i--) 83 if (b[i] == '\\') { 84 if (escaped) 85 escaped = 0; 86 else 87 escaped = 1; 88 } else 89 break; 90 if (!escaped) 91 lb--; 92 } 93 94 /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */ 95 if (lb == 0U) 96 return (1); 97 98 /* 'b' longer than 'a' means 'a' can't be in 'b'. */ 99 if (lb > la) 100 return (0); 101 102 /* 'a' and 'b' being equal at this point indicates sameness. */ 103 if (lb == la) 104 return (strncasecmp(a, b, lb) == 0); 105 106 /* Ok, we know la > lb. */ 107 108 diff = la - lb; 109 110 /* 111 * If 'a' is only 1 character longer than 'b', then it can't be 112 * a subdomain of 'b' (because of the need for the '.' label 113 * separator). 114 */ 115 if (diff < 2) 116 return (0); 117 118 /* 119 * If the character before the last 'lb' characters of 'b' 120 * isn't '.', then it can't be a match (this lets us avoid 121 * having "foobar.com" match "bar.com"). 122 */ 123 if (a[diff - 1] != '.') 124 return (0); 125 126 /* 127 * We're not sure about that '.', however. It could be escaped 128 * and thus not a really a label separator. 129 */ 130 escaped = 0; 131 for (i = diff - 2; i >= 0; i--) 132 if (a[i] == '\\') { 133 if (escaped) 134 escaped = 0; 135 else 136 escaped = 1; 137 } else 138 break; 139 if (escaped) 140 return (0); 141 142 /* Now compare aligned trailing substring. */ 143 cp = a + diff; 144 return (strncasecmp(cp, b, lb) == 0); 145 } 146 147 /* 148 * int 149 * ns_subdomain(a, b) 150 * is "a" a subdomain of "b"? 151 */ 152 int 153 ns_subdomain(const char *a, const char *b) { 154 return (ns_samename(a, b) != 1 && ns_samedomain(a, b)); 155 } 156 #endif 157 158 /* 159 * int 160 * ns_makecanon(src, dst, dstsize) 161 * make a canonical copy of domain name "src" 162 * notes: 163 * foo -> foo. 164 * foo. -> foo. 165 * foo.. -> foo. 166 * foo\. -> foo\.. 167 * foo\\. -> foo\\. 168 */ 169 170 int 171 ns_makecanon(const char *src, char *dst, size_t dstsize) { 172 size_t n = strlen(src); 173 174 if (n + sizeof "." > dstsize) { /* Note: sizeof == 2 */ 175 errno = EMSGSIZE; 176 return (-1); 177 } 178 strcpy(dst, src); 179 while (n >= 1U && dst[n - 1] == '.') /* Ends in "." */ 180 if (n >= 2U && dst[n - 2] == '\\' && /* Ends in "\." */ 181 (n < 3U || dst[n - 3] != '\\')) /* But not "\\." */ 182 break; 183 else 184 dst[--n] = '\0'; 185 dst[n++] = '.'; 186 dst[n] = '\0'; 187 return (0); 188 } 189 190 /* 191 * int 192 * ns_samename(a, b) 193 * determine whether domain name "a" is the same as domain name "b" 194 * return: 195 * -1 on error 196 * 0 if names differ 197 * 1 if names are the same 198 */ 199 200 int 201 ns_samename(const char *a, const char *b) { 202 char ta[NS_MAXDNAME], tb[NS_MAXDNAME]; 203 204 if (ns_makecanon(a, ta, sizeof ta) < 0 || 205 ns_makecanon(b, tb, sizeof tb) < 0) 206 return (-1); 207 if (strcasecmp(ta, tb) == 0) 208 return (1); 209 else 210 return (0); 211 } 212
