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	/*
	* Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package sun.security.x509;

	import java.io.IOException;
	import java.util.Locale;

	import sun.security.util.*;

	/**
	* This class implements the DNSName as required by the GeneralNames
	* ASN.1 object.
	* <p>
	* [RFC5280] When the subjectAltName extension contains a domain name system
	* label, the domain name MUST be stored in the dNSName (an IA5String).
	* The name MUST be in the "preferred name syntax", as specified by
	* Section 3.5 of [RFC1034] and as modified by Section 2.1 of
	* [RFC1123]. Note that while uppercase and lowercase letters are
	* allowed in domain names, no significance is attached to the case. In
	* addition, while the string " " is a legal domain name, subjectAltName
	* extensions with a dNSName of " " MUST NOT be used. Finally, the use
	* of the DNS representation for Internet mail addresses
	* (subscriber.example.com instead of subscriber@example.com) MUST NOT
	* be used; such identities are to be encoded as rfc822Name.
	* <p>
	* @author Amit Kapoor
	* @author Hemma Prafullchandra
	*/
	public class DNSName implements GeneralNameInterface {
	private String name;

	private static final String alphaDigits =
	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

	/**
	* Create the DNSName object from the passed encoded Der value.
	*
	* @param derValue the encoded DER DNSName.
	* @exception IOException on error.
	*/
	public DNSName(DerValue derValue) throws IOException {
	name = derValue.getIA5String();
	}

	/**
	* Create the DNSName object with the specified name.
	*
	* @param name the DNSName.
	* @throws IOException if the name is not a valid DNSName subjectAltName
	*/
	public DNSName(String name) throws IOException {
	if (name == null \|\| name.length() == 0)
	throw new IOException("DNSName must not be null or empty");
	if (name.contains(" "))
	throw new IOException("DNSName with blank components is not permitted");
	if (name.startsWith(".") \|\| name.endsWith("."))
	throw new IOException("DNSName may not begin or end with a .");
	/*
	* Name will consist of label components separated by "."
	* startIndex is the index of the first character of a component
	* endIndex is the index of the last character of a component plus 1
	*/
	for (int endIndex,startIndex = 0; startIndex < name.length(); startIndex = endIndex+1) {
	endIndex = name.indexOf('.', startIndex);
	if (endIndex < 0) {
	endIndex = name.length();
	}
	if (endIndex - startIndex < 1)
	throw new IOException("DNSName with empty components are not permitted");

	// RFC 1123: DNSName components must begin with a letter or digit
	if (alphaDigits.indexOf(name.charAt(startIndex)) < 0)
	throw new IOException("DNSName components must begin with a letter or digit");
	//nonStartIndex: index for characters in the component beyond the first one
	for (int nonStartIndex=startIndex+1; nonStartIndex < endIndex; nonStartIndex++) {
	char x = name.charAt(nonStartIndex);
	if ((alphaDigits).indexOf(x) < 0 && x != '-')
	throw new IOException("DNSName components must consist of letters, digits, and hyphens");
	}
	}
	this.name = name;
	}


	/**
	* Return the type of the GeneralName.
	*/
	public int getType() {
	return (GeneralNameInterface.NAME_DNS);
	}

	/**
	* Return the actual name value of the GeneralName.
	*/
	public String getName() {
	return name;
	}

	/**
	* Encode the DNSName into the DerOutputStream.
	*
	* @param out the DER stream to encode the DNSName to.
	* @exception IOException on encoding errors.
	*/
	public void encode(DerOutputStream out) throws IOException {
	out.putIA5String(name);
	}

	/**
	* Convert the name into user readable string.
	*/
	public String toString() {
	return ("DNSName: " + name);
	}

	/**
	* Compares this name with another, for equality.
	*
	* @return true iff the names are equivalent
	* according to RFC5280.
	*/
	public boolean equals(Object obj) {
	if (this == obj)
	return true;

	if (!(obj instanceof DNSName))
	return false;

	DNSName other = (DNSName)obj;

	// RFC5280 mandates that these names are
	// not case-sensitive
	return name.equalsIgnoreCase(other.name);
	}

	/**
	* Returns the hash code value for this object.
	*
	* @return a hash code value for this object.
	*/
	public int hashCode() {
	return name.toUpperCase(Locale.ENGLISH).hashCode();
	}

	/**
	* Return type of constraint inputName places on this name:<ul>
	* <li>NAME_DIFF_TYPE = -1: input name is different type from name (i.e. does not constrain).
	* <li>NAME_MATCH = 0: input name matches name.
	* <li>NAME_NARROWS = 1: input name narrows name (is lower in the naming subtree)
	* <li>NAME_WIDENS = 2: input name widens name (is higher in the naming subtree)
	* <li>NAME_SAME_TYPE = 3: input name does not match or narrow name, but is same type.
	* </ul>. These results are used in checking NameConstraints during
	* certification path verification.
	* <p>
	* RFC5280: DNS name restrictions are expressed as host.example.com.
	* Any DNS name that can be constructed by simply adding zero or more
	* labels to the left-hand side of the name satisfies the name constraint.
	* For example, www.host.example.com would satisfy the constraint but
	* host1.example.com would not.
	* <p>
	* draft-ietf-pkix-new-part1-00.txt: DNSName restrictions are expressed as foo.bar.com.
	* Any DNSName that
	* can be constructed by simply adding to the left hand side of the name
	* satisfies the name constraint. For example, www.foo.bar.com would
	* satisfy the constraint but foo1.bar.com would not.
	* <p>
	* RFC1034: By convention, domain names can be stored with arbitrary case, but
	* domain name comparisons for all present domain functions are done in a
	* case-insensitive manner, assuming an ASCII character set, and a high
	* order zero bit.
	* <p>
	* @param inputName to be checked for being constrained
	* @returns constraint type above
	* @throws UnsupportedOperationException if name is not exact match, but narrowing and widening are
	* not supported for this name type.
	*/
	public int constrains(GeneralNameInterface inputName) throws UnsupportedOperationException {
	int constraintType;
	if (inputName == null)
	constraintType = NAME_DIFF_TYPE;
	else if (inputName.getType() != NAME_DNS)
	constraintType = NAME_DIFF_TYPE;
	else {
	String inName =
	(((DNSName)inputName).getName()).toLowerCase(Locale.ENGLISH);
	String thisName = name.toLowerCase(Locale.ENGLISH);
	if (inName.equals(thisName))
	constraintType = NAME_MATCH;
	else if (thisName.endsWith(inName)) {
	int inNdx = thisName.lastIndexOf(inName);
	if (thisName.charAt(inNdx-1) == '.' )
	constraintType = NAME_WIDENS;
	else
	constraintType = NAME_SAME_TYPE;
	} else if (inName.endsWith(thisName)) {
	int ndx = inName.lastIndexOf(thisName);
	if (inName.charAt(ndx-1) == '.' )
	constraintType = NAME_NARROWS;
	else
	constraintType = NAME_SAME_TYPE;
	} else {
	constraintType = NAME_SAME_TYPE;
	}
	}
	return constraintType;
	}

	/**
	* Return subtree depth of this name for purposes of determining
	* NameConstraints minimum and maximum bounds and for calculating
	* path lengths in name subtrees.
	*
	* @returns distance of name from root
	* @throws UnsupportedOperationException if not supported for this name type
	*/
	public int subtreeDepth() throws UnsupportedOperationException {
	// subtree depth is always at least 1
	int sum = 1;

	// count dots
	for (int i = name.indexOf('.'); i >= 0; i = name.indexOf('.', i + 1)) {
	++sum;
	}

	return sum;
	}

	}

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