diff options
Diffstat (limited to 'lib/libc/nameser/ns_samedomain.c')
| -rw-r--r-- | lib/libc/nameser/ns_samedomain.c | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/lib/libc/nameser/ns_samedomain.c b/lib/libc/nameser/ns_samedomain.c new file mode 100644 index 000000000000..9c43c79e4c6d --- /dev/null +++ b/lib/libc/nameser/ns_samedomain.c @@ -0,0 +1,211 @@ +/* + * 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 ISC DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC 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. + */ + +#ifndef lint +static const char rcsid[] = "$Id: ns_samedomain.c,v 1.5.18.1 2005/04/27 05:01:09 sra Exp $"; +#endif +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include "port_before.h" + +#include <sys/types.h> +#include <arpa/nameser.h> +#include <errno.h> +#include <string.h> + +#include "port_after.h" + +/*% + * Check whether a name belongs to a domain. + * + * Inputs: + *\li a - the domain whose ancestory 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); +} + +#ifndef _LIBC +/*% + * 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)); +} +#endif + +/*% + * 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 */ + 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); +} + +/*% + * 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); +} + +/*! \file */ |