diff options
Diffstat (limited to 'resolv/ns_samedomain.c')
| -rw-r--r-- | resolv/ns_samedomain.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/resolv/ns_samedomain.c b/resolv/ns_samedomain.c new file mode 100644 index 0000000..bac5a63 --- /dev/null +++ b/resolv/ns_samedomain.c @@ -0,0 +1,202 @@ +/* + * 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. + */ + +#ifndef lint +static const char rcsid[] = "$Id$"; +#endif + +#include <sys/types.h> +#include <arpa/nameser.h> +#include <errno.h> +#include <string.h> + +/* + * int + * ns_samedomain(a, b) + * Check whether a name belongs to a domain. + * Inputs: + * a - the domain whose ancestory is being verified + * b - the potential ancestor we're checking against + * Return: + * boolean - is a at or below b? + * Notes: + * 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. + * + * "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 != 0 && 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 != 0 && 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 == 0) + 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); +} + +/* + * int + * ns_subdomain(a, b) + * 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)); +} + +/* + * int + * ns_makecanon(src, dst, dstsize) + * make a canonical copy of domain name "src" + * notes: + * foo -> foo. + * foo. -> foo. + * foo.. -> foo. + * foo\. -> foo\.. + * foo\\. -> foo\\. + */ + +int +ns_makecanon(const char *src, char *dst, size_t dstsize) { + size_t n = strlen(src); + + if (n + sizeof "." > dstsize) { + __set_errno (EMSGSIZE); + return (-1); + } + strcpy(dst, src); + while (n > 0 && dst[n - 1] == '.') /* Ends in "." */ + if (n > 1 && dst[n - 2] == '\\' && /* Ends in "\." */ + (n < 2 || dst[n - 3] != '\\')) /* But not "\\." */ + break; + else + dst[--n] = '\0'; + dst[n++] = '.'; + dst[n] = '\0'; + return (0); +} + +/* + * int + * ns_samename(a, b) + * determine whether domain name "a" is the same as domain name "b" + * return: + * -1 on error + * 0 if names differ + * 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); +} |