1 /* $NetBSD: ns_samedomain.c,v 1.8 2012/11/22 20:22:31 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 1.6 2005/04/27 04:56:40 sra Exp"; 24 #else 25 __RCSID("$NetBSD: ns_samedomain.c,v 1.8 2012/11/22 20:22:31 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 #ifdef _LIBRESOLV 35 /* 36 * Check whether a name belongs to a domain. 37 * 38 * Inputs: 39 * a - the domain whose ancestory is being verified 40 * b - the potential ancestor we're checking against 41 * 42 * Return: 43 * boolean - is a at or below b? 44 * 45 * Notes: 46 * Trailing dots are first removed from name and domain. 47 * Always compare complete subdomains, not only whether the 48 * domain name is the trailing string of the given name. 49 * 50 * "host.foobar.top" lies in "foobar.top" and in "top" and in "" 51 * but NOT in "bar.top" 52 */ 53 54 int 55 ns_samedomain(const char *a, const char *b) { 56 size_t la, lb, i; 57 int diff, escaped; 58 const char *cp; 59 60 la = strlen(a); 61 lb = strlen(b); 62 63 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */ 64 if (la != 0U && a[la - 1] == '.') { 65 escaped = 0; 66 /* Note this loop doesn't get executed if la==1. */ 67 for (i = la - 1; i > 0; i--) 68 if (a[i - 1] == '\\') { 69 if (escaped) 70 escaped = 0; 71 else 72 escaped = 1; 73 } else 74 break; 75 if (!escaped) 76 la--; 77 } 78 79 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */ 80 if (lb != 0U && b[lb - 1] == '.') { 81 escaped = 0; 82 /* note this loop doesn't get executed if lb==1 */ 83 for (i = lb - 1; i > 0; i--) 84 if (b[i - 1] == '\\') { 85 if (escaped) 86 escaped = 0; 87 else 88 escaped = 1; 89 } else 90 break; 91 if (!escaped) 92 lb--; 93 } 94 95 /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */ 96 if (lb == 0U) 97 return (1); 98 99 /* 'b' longer than 'a' means 'a' can't be in 'b'. */ 100 if (lb > la) 101 return (0); 102 103 /* 'a' and 'b' being equal at this point indicates sameness. */ 104 if (lb == la) 105 return (strncasecmp(a, b, lb) == 0); 106 107 /* Ok, we know la > lb. */ 108 109 diff = (int)(la - lb); 110 111 /* 112 * If 'a' is only 1 character longer than 'b', then it can't be 113 * a subdomain of 'b' (because of the need for the '.' label 114 * separator). 115 */ 116 if (diff < 2) 117 return (0); 118 119 /* 120 * If the character before the last 'lb' characters of 'b' 121 * isn't '.', then it can't be a match (this lets us avoid 122 * having "foobar.com" match "bar.com"). 123 */ 124 if (a[diff - 1] != '.') 125 return (0); 126 127 /* 128 * We're not sure about that '.', however. It could be escaped 129 * and thus not a really a label separator. 130 */ 131 escaped = 0; 132 for (i = diff - 1; i > 0; i--) 133 if (a[i - 1] == '\\') { 134 if (escaped) 135 escaped = 0; 136 else 137 escaped = 1; 138 } else 139 break; 140 if (escaped) 141 return (0); 142 143 /* Now compare aligned trailing substring. */ 144 cp = a + diff; 145 return (strncasecmp(cp, b, lb) == 0); 146 } 147 148 /* 149 * is "a" a subdomain of "b"? 150 */ 151 int 152 ns_subdomain(const char *a, const char *b) { 153 return (ns_samename(a, b) != 1 && ns_samedomain(a, b)); 154 } 155 #endif 156 157 #ifdef _LIBC 158 /* 159 * make a canonical copy of domain name "src" 160 * 161 * notes: 162 * foo -> foo. 163 * foo. -> foo. 164 * foo.. -> foo. 165 * foo\. -> foo\.. 166 * foo\\. -> foo\\. 167 */ 168 169 int 170 ns_makecanon(const char *src, char *dst, size_t dstsize) { 171 size_t n = strlen(src); 172 173 if (n + sizeof "." > dstsize) { /* Note: sizeof == 2 */ 174 errno = EMSGSIZE; 175 return (-1); 176 } 177 strcpy(dst, src); 178 while (n >= 1U && dst[n - 1] == '.') /* Ends in "." */ 179 if (n >= 2U && dst[n - 2] == '\\' && /* Ends in "\." */ 180 (n < 3U || dst[n - 3] != '\\')) /* But not "\\." */ 181 break; 182 else 183 dst[--n] = '\0'; 184 dst[n++] = '.'; 185 dst[n] = '\0'; 186 return (0); 187 } 188 189 /* 190 * determine whether domain name "a" is the same as domain name "b" 191 * 192 * return: 193 * -1 on error 194 * 0 if names differ 195 * 1 if names are the same 196 */ 197 198 int 199 ns_samename(const char *a, const char *b) { 200 char ta[NS_MAXDNAME], tb[NS_MAXDNAME]; 201 202 if (ns_makecanon(a, ta, sizeof ta) < 0 || 203 ns_makecanon(b, tb, sizeof tb) < 0) 204 return (-1); 205 if (strcasecmp(ta, tb) == 0) 206 return (1); 207 else 208 return (0); 209 } 210 #endif 211
