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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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.

[RFC2459] When the subjectAltName extension contains a domain name service
label, the domain name MUST be stored in the dNSName (an IA5String).
The name MUST be in the "preferred name syntax," as specified by RFC
1034 [RFC 1034]. Note that while upper and lower case letters are
allowed in domain names, no signifigance is attached to the case.  In
addition, while the string " " is a legal domain name, subjectAltName
extensions with a dNSName " " are not permitted.  Finally, the use of
the DNS representation for Internet mail addresses (wpolk.nist.gov
instead of wpolk@nist.gov) is not permitted; such identities are to
be encoded as rfc822Name.

Author:
Amit Kapoor, Hemma Prafullchandra/**
 * This class implements the DNSName as required by the GeneralNames
 * ASN.1 object.
 * <p>
 * [RFC2459] When the subjectAltName extension contains a domain name service
 * label, the domain name MUST be stored in the dNSName (an IA5String).
 * The name MUST be in the "preferred name syntax," as specified by RFC
 * 1034 [RFC 1034]. Note that while upper and lower case letters are
 * allowed in domain names, no signifigance is attached to the case.  In
 * addition, while the string " " is a legal domain name, subjectAltName
 * extensions with a dNSName " " are not permitted.  Finally, the use of
 * the DNS representation for Internet mail addresses (wpolk.nist.gov
 * instead of wpolk@nist.gov) is not permitted; 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 alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
    private static final String digitsAndHyphen = "0123456789-";
    private static final String alphaDigitsAndHyphen = alpha + digitsAndHyphen;

    
Create the DNSName object from the passed encoded Der value.
Params:
derValue – the encoded DER DNSName.
Throws:
IOException – on error./**
     * 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.
Params:
name – the DNSName.
Throws:
IOException – if the name is not a valid DNSName subjectAltName/**
     * 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("DNS name must not be null");
        if (name.indexOf(' ') != -1)
            throw new IOException("DNS names or NameConstraints with blank components are not permitted");
        if (name.charAt(0) == '.' || name.charAt(name.length() -1) == '.')
            throw new IOException("DNS names or NameConstraints 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 SubjectAltNames with empty components are not permitted");

            //DNSName components must begin with a letter A-Z or a-z
            if (alpha.indexOf(name.charAt(startIndex)) < 0)
                throw new IOException("DNSName components must begin with a letter");
            //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 ((alphaDigitsAndHyphen).indexOf(x) < 0)
                    throw new IOException("DNSName components must consist of letters, digits, and hyphens");
            }
        }
        this.name = name;
    }

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

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

    
Encode the DNS name into the DerOutputStream.
Params:
out – the DER stream to encode the DNSName to.
Throws:
IOException – on encoding errors./**
     * Encode the DNS name 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.
/**
     * Convert the name into user readable string.
     */
    public String toString() {
        return ("DNSName: " + name);
    }

    
Compares this name with another, for equality.
Returns:
true iff the names are equivalent
according to RFC2459./**
     * Compares this name with another, for equality.
     *
     * @return true iff the names are equivalent
     * according to RFC2459.
     */
    public boolean equals(Object obj) {
        if (this == obj)
            return true;

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

        DNSName other = (DNSName)obj;

        // RFC2459 mandates that these names are
        // not case-sensitive
        return name.equalsIgnoreCase(other.name);
    }

    
Returns the hash code value for this object.
Returns:
a hash code value for this object./**
     * 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:

  
NAME_DIFF_TYPE = -1: input name is different type from name (i.e. does not constrain).
  
NAME_MATCH = 0: input name matches name.
  
NAME_NARROWS = 1: input name narrows name (is lower in the naming subtree)
  
NAME_WIDENS = 2: input name widens name (is higher in the naming subtree)
  
NAME_SAME_TYPE = 3: input name does not match or narrow name, but is same type.
.  These results are used in checking NameConstraints during
certification path verification.

RFC2459: DNS name restrictions are expressed as foo.bar.com. Any subdomain
satisfies the name constraint. For example, www.foo.bar.com would
satisfy the constraint but bigfoo.bar.com would not.

draft-ietf-pkix-new-part1-00.txt:  DNS name restrictions are expressed as foo.bar.com.
Any DNS name 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.

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.

Params:
inputName – to be checked for being constrained
Throws:
UnsupportedOperationException – if name is not exact match, but narrowing and widening are
         not supported for this name type.
@returns
constraint type above/**
     * 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>
     * RFC2459: DNS name restrictions are expressed as foo.bar.com. Any subdomain
     * satisfies the name constraint. For example, www.foo.bar.com would
     * satisfy the constraint but bigfoo.bar.com would not.
     * <p>
     * draft-ietf-pkix-new-part1-00.txt:  DNS name restrictions are expressed as foo.bar.com.
     * Any DNS name 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.
Throws:
UnsupportedOperationException – if not supported for this name type
@returns
distance of name from root/**
     * 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;
    }

}