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