1 /* 2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 3 * Copyright (c) 1995,1999 by Internet Software Consortium. 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 15 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #ifndef lint 19 static const char rcsid[] = "$Id: ns_samedomain.c,v 1.1.2.2.4.2 2004/03/16 12:34:17 marka Exp $"; 20 #endif 21 #include <sys/cdefs.h> 22 __FBSDID("$FreeBSD$"); 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 * int 35 * ns_samedomain(a, b) 36 * Check whether a name belongs to a domain. 37 * Inputs: 38 * a - the domain whose ancestory is being verified 39 * b - the potential ancestor we're checking against 40 * Return: 41 * boolean - is a at or below b? 42 * Notes: 43 * Trailing dots are first removed from name and domain. 44 * Always compare complete subdomains, not only whether the 45 * domain name is the trailing string of the given name. 46 * 47 * "host.foobar.top" lies in "foobar.top" and in "top" and in "" 48 * but NOT in "bar.top" 49 */ 50 51 int 52 ns_samedomain(const char *a, const char *b) { 53 size_t la, lb; 54 int diff, i, escaped; 55 const char *cp; 56 57 la = strlen(a); 58 lb = strlen(b); 59 60 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */ 61 if (la != 0U && a[la - 1] == '.') { 62 escaped = 0; 63 /* Note this loop doesn't get executed if la==1. */ 64 for (i = la - 2; i >= 0; i--) 65 if (a[i] == '\\') { 66 if (escaped) 67 escaped = 0; 68 else 69 escaped = 1; 70 } else 71 break; 72 if (!escaped) 73 la--; 74 } 75 76 /* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */ 77 if (lb != 0U && b[lb - 1] == '.') { 78 escaped = 0; 79 /* note this loop doesn't get executed if lb==1 */ 80 for (i = lb - 2; i >= 0; i--) 81 if (b[i] == '\\') { 82 if (escaped) 83 escaped = 0; 84 else 85 escaped = 1; 86 } else 87 break; 88 if (!escaped) 89 lb--; 90 } 91 92 /* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */ 93 if (lb == 0U) 94 return (1); 95 96 /* 'b' longer than 'a' means 'a' can't be in 'b'. */ 97 if (lb > la) 98 return (0); 99 100 /* 'a' and 'b' being equal at this point indicates sameness. */ 101 if (lb == la) 102 return (strncasecmp(a, b, lb) == 0); 103 104 /* Ok, we know la > lb. */ 105 106 diff = la - lb; 107 108 /* 109 * If 'a' is only 1 character longer than 'b', then it can't be 110 * a subdomain of 'b' (because of the need for the '.' label 111 * separator). 112 */ 113 if (diff < 2) 114 return (0); 115 116 /* 117 * If the character before the last 'lb' characters of 'b' 118 * isn't '.', then it can't be a match (this lets us avoid 119 * having "foobar.com" match "bar.com"). 120 */ 121 if (a[diff - 1] != '.') 122 return (0); 123 124 /* 125 * We're not sure about that '.', however. It could be escaped 126 * and thus not a really a label separator. 127 */ 128 escaped = 0; 129 for (i = diff - 2; i >= 0; i--) 130 if (a[i] == '\\') { 131 if (escaped) 132 escaped = 0; 133 else 134 escaped = 1; 135 } else 136 break; 137 if (escaped) 138 return (0); 139 140 /* Now compare aligned trailing substring. */ 141 cp = a + diff; 142 return (strncasecmp(cp, b, lb) == 0); 143 } 144 145 #ifndef _LIBC 146 /* 147 * int 148 * ns_subdomain(a, b) 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 /* 158 * int 159 * ns_makecanon(src, dst, dstsize) 160 * make a canonical copy of domain name "src" 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 * int 191 * ns_samename(a, b) 192 * determine whether domain name "a" is the same as domain name "b" 193 * return: 194 * -1 on error 195 * 0 if names differ 196 * 1 if names are the same 197 */ 198 199 int 200 ns_samename(const char *a, const char *b) { 201 char ta[NS_MAXDNAME], tb[NS_MAXDNAME]; 202 203 if (ns_makecanon(a, ta, sizeof ta) < 0 || 204 ns_makecanon(b, tb, sizeof tb) < 0) 205 return (-1); 206 if (strcasecmp(ta, tb) == 0) 207 return (1); 208 else 209 return (0); 210 } 211