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 #ifndef _LIBC 34 /* 35 * int 36 * ns_samedomain(a, b) 37 * Check whether a name belongs to a domain. 38 * Inputs: 39 * a - the domain whose ancestory is being verified 40 * b - the potential ancestor we're checking against 41 * Return: 42 * boolean - is a at or below b? 43 * Notes: 44 * 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 * "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 * 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