/*
 * Copyright (c) 2005 Sendmail, Inc. and its suppliers.
 *	All rights reserved.
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the sendmail distribution.
 */

#include "sm/generic.h"
SM_RCSID("@(#)$Id: validdomain.c,v 1.5 2006/12/25 20:37:01 ca Exp $")

#include "sm/assert.h"
#include "sm/error.h"
#include "sm/ctype.h"
#include "sm/net.h"
#include "sm/rfc2821.h"
#include "sm/str.h"
#include "sm/misc.h"

/*
**  VALIDDOMAIN -- check whether a domain is syntactically valid
**
**	Parameters:
**		str -- string that stores domain
**		flags -- flags to influence checks
**
**	Returns:
**		true iff domain is syntactically valid
*/

bool
validdomain(sm_str_P str, uint flags)
{
	uint i, len, beginsub;
	uchar ch, lastch;

	if (NULL == str)
		return false;
	len = sm_str_getlen(str);
	if (0 == len)
		return false;
	ch = sm_str_rd_elem(str, 0);

	if (ch == '[') {
		sm_ret_T ret;
		char *begin, *end;
		ipv4_T ipv4;

		begin = (char *) sm_str_getdata(str);
		if (NULL == begin)
			return true;
		ret = sm_inet_a2ipv4(begin, &end, &ipv4);
		return sm_is_success(ret);
	}

	beginsub = 0;
	do {
		/*
		**  Domain = (sub-domain 1*("." sub-domain)) / address-literal
		**  sub-domain = Let-dig [Ldh-str]
		**  Let-dig = ALPHA / DIGIT
		**  Ldh-str = *( ALPHA / DIGIT / "-" ) Let-dig
		*/

		ch = sm_str_rd_elem(str, beginsub);
		if (!ISALNUM(ch))
			return false;
		for (i = beginsub; i < len; ++i) {
			lastch = ch;
			ch = sm_str_rd_elem(str, i);
			if ('.' == ch) {
				if (!ISALNUM(lastch))
					return false;
				beginsub = i + 1;
				break;
			}
			if (!(ISALNUM(ch) || ch == '-'
			      || (HAS_R2821(flags, R2821__) && ch == '_')))
				return false;
		}
		SM_ASSERT(i >= len || '.' == ch);
		if ('.' == ch && beginsub >= len)
			return !HAS_R2821(flags, R2821_NO_TRLDOT);
	} while (i < len);
	if (!ISALNUM(ch)) {
		if ('.' == ch)
			return !HAS_R2821(flags, R2821_NO_TRLDOT);
		return false;
	}
	return true;
}