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glibc/resolv/ns_samedomain.c
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/* | |
* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") | |
* Copyright (c) 1995,1999 by Internet Software Consortium. | |
* | |
* Permission to use, copy, modify, and distribute this software for any | |
* purpose with or without fee is hereby granted, provided that the above | |
* copyright notice and this permission notice appear in all copies. | |
* | |
* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS | |
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES | |
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE | |
* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL | |
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR | |
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS | |
* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS | |
* SOFTWARE. | |
*/ | |
#if !defined(_LIBC) && !defined(lint) | |
static const char rcsid[] = "$BINDId: ns_samedomain.c,v 8.9 1999/10/15 21:06:51 vixie Exp $"; | |
#endif | |
#include <sys/types.h> | |
#include <arpa/nameser.h> | |
#include <errno.h> | |
#include <string.h> | |
/*% | |
* Check whether a name belongs to a domain. | |
* | |
* Inputs: | |
*\li a - the domain whose ancestry is being verified | |
*\li b - the potential ancestor we're checking against | |
* | |
* Return: | |
*\li boolean - is a at or below b? | |
* | |
* Notes: | |
*\li Trailing dots are first removed from name and domain. | |
* Always compare complete subdomains, not only whether the | |
* domain name is the trailing string of the given name. | |
* | |
*\li "host.foobar.top" lies in "foobar.top" and in "top" and in "" | |
* but NOT in "bar.top" | |
*/ | |
int | |
ns_samedomain(const char *a, const char *b) { | |
size_t la, lb; | |
int diff, i, escaped; | |
const char *cp; | |
la = strlen(a); | |
lb = strlen(b); | |
/* Ignore a trailing label separator (i.e. an unescaped dot) in 'a'. */ | |
if (la != 0U && a[la - 1] == '.') { | |
escaped = 0; | |
/* Note this loop doesn't get executed if la==1. */ | |
for (i = la - 2; i >= 0; i--) | |
if (a[i] == '\\') { | |
if (escaped) | |
escaped = 0; | |
else | |
escaped = 1; | |
} else | |
break; | |
if (!escaped) | |
la--; | |
} | |
/* Ignore a trailing label separator (i.e. an unescaped dot) in 'b'. */ | |
if (lb != 0U && b[lb - 1] == '.') { | |
escaped = 0; | |
/* note this loop doesn't get executed if lb==1 */ | |
for (i = lb - 2; i >= 0; i--) | |
if (b[i] == '\\') { | |
if (escaped) | |
escaped = 0; | |
else | |
escaped = 1; | |
} else | |
break; | |
if (!escaped) | |
lb--; | |
} | |
/* lb == 0 means 'b' is the root domain, so 'a' must be in 'b'. */ | |
if (lb == 0U) | |
return (1); | |
/* 'b' longer than 'a' means 'a' can't be in 'b'. */ | |
if (lb > la) | |
return (0); | |
/* 'a' and 'b' being equal at this point indicates sameness. */ | |
if (lb == la) | |
return (strncasecmp(a, b, lb) == 0); | |
/* Ok, we know la > lb. */ | |
diff = la - lb; | |
/* | |
* If 'a' is only 1 character longer than 'b', then it can't be | |
* a subdomain of 'b' (because of the need for the '.' label | |
* separator). | |
*/ | |
if (diff < 2) | |
return (0); | |
/* | |
* If the character before the last 'lb' characters of 'b' | |
* isn't '.', then it can't be a match (this lets us avoid | |
* having "foobar.com" match "bar.com"). | |
*/ | |
if (a[diff - 1] != '.') | |
return (0); | |
/* | |
* We're not sure about that '.', however. It could be escaped | |
* and thus not a really a label separator. | |
*/ | |
escaped = 0; | |
for (i = diff - 2; i >= 0; i--) | |
if (a[i] == '\\') { | |
if (escaped) | |
escaped = 0; | |
else | |
escaped = 1; | |
} else | |
break; | |
if (escaped) | |
return (0); | |
/* Now compare aligned trailing substring. */ | |
cp = a + diff; | |
return (strncasecmp(cp, b, lb) == 0); | |
} | |
libresolv_hidden_def (ns_samedomain) | |
/*% | |
* is "a" a subdomain of "b"? | |
*/ | |
int | |
ns_subdomain(const char *a, const char *b) { | |
return (ns_samename(a, b) != 1 && ns_samedomain(a, b)); | |
} | |
/*% | |
* make a canonical copy of domain name "src" | |
* | |
* notes: | |
* \code | |
* foo -> foo. | |
* foo. -> foo. | |
* foo.. -> foo. | |
* foo\. -> foo\.. | |
* foo\\. -> foo\\. | |
* \endcode | |
*/ | |
int | |
ns_makecanon(const char *src, char *dst, size_t dstsize) { | |
size_t n = strlen(src); | |
if (n + sizeof "." > dstsize) { /*%< Note: sizeof == 2 */ | |
__set_errno (EMSGSIZE); | |
return (-1); | |
} | |
strcpy(dst, src); | |
while (n >= 1U && dst[n - 1] == '.') /*%< Ends in "." */ | |
if (n >= 2U && dst[n - 2] == '\\' && /*%< Ends in "\." */ | |
(n < 3U || dst[n - 3] != '\\')) /*%< But not "\\." */ | |
break; | |
else | |
dst[--n] = '\0'; | |
dst[n++] = '.'; | |
dst[n] = '\0'; | |
return (0); | |
} | |
libresolv_hidden_def (ns_makecanon) | |
/*% | |
* determine whether domain name "a" is the same as domain name "b" | |
* | |
* return: | |
*\li -1 on error | |
*\li 0 if names differ | |
*\li 1 if names are the same | |
*/ | |
int | |
ns_samename(const char *a, const char *b) { | |
char ta[NS_MAXDNAME], tb[NS_MAXDNAME]; | |
if (ns_makecanon(a, ta, sizeof ta) < 0 || | |
ns_makecanon(b, tb, sizeof tb) < 0) | |
return (-1); | |
if (strcasecmp(ta, tb) == 0) | |
return (1); | |
else | |
return (0); | |
} | |
libresolv_hidden_def (ns_samename) | |
/*! \file */ |