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package sun.security.x509;

import java.io.IOException;
import java.io.OutputStream;
import java.util.Enumeration;

import sun.security.util.*;


This represents the Subject Alternative Name Extension.
This extension, if present, allows the subject to specify multiple
alternative names.

Extensions are represented as a sequence of the extension identifier
(Object Identifier), a boolean flag stating whether the extension is to
be treated as being critical and the extension value itself (this is again
a DER encoding of the extension value).


The ASN.1 syntax for this is:

SubjectAltName ::= GeneralNames
GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName



Author:Amit Kapoor, Hemma Prafullchandra
See Also:
/**
 * This represents the Subject Alternative Name Extension.
 *
 * This extension, if present, allows the subject to specify multiple
 * alternative names.
 *
 * <p>Extensions are represented as a sequence of the extension identifier
 * (Object Identifier), a boolean flag stating whether the extension is to
 * be treated as being critical and the extension value itself (this is again
 * a DER encoding of the extension value).
 * <p>
 * The ASN.1 syntax for this is:
 * <pre>
 * SubjectAltName ::= GeneralNames
 * GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName
 * </pre>
 * @author Amit Kapoor
 * @author Hemma Prafullchandra
 * @see Extension
 * @see CertAttrSet
 */
public class SubjectAlternativeNameExtension extends Extension
implements CertAttrSet<String> {
    
Identifier for this attribute, to be used with the
get, set, delete methods of Certificate, x509 type.

/**
     * Identifier for this attribute, to be used with the
     * get, set, delete methods of Certificate, x509 type.
     */
    public static final String IDENT =
                         "x509.info.extensions.SubjectAlternativeName";
    
Attribute names.

/**
     * Attribute names.
     */
    public static final String NAME = "SubjectAlternativeName";
    public static final String SUBJECT_NAME = "subject_name";

    // private data members
    GeneralNames        names = null;

    // Encode this extension
    private void encodeThis() throws IOException {
        if (names == null || names.isEmpty()) {
            this.extensionValue = null;
            return;
        }
        DerOutputStream os = new DerOutputStream();
        names.encode(os);
        this.extensionValue = os.toByteArray();
    }

    
Create a SubjectAlternativeNameExtension with the passed GeneralNames.
The extension is marked non-critical.

Params:
  • names – the GeneralNames for the subject.
Throws:
/**
     * Create a SubjectAlternativeNameExtension with the passed GeneralNames.
     * The extension is marked non-critical.
     *
     * @param names the GeneralNames for the subject.
     * @exception IOException on error.
     */
    public SubjectAlternativeNameExtension(GeneralNames names)
    throws IOException {
        this(Boolean.FALSE, names);
    }

    
Create a SubjectAlternativeNameExtension with the specified
criticality and GeneralNames.

Params:
  • critical – true if the extension is to be treated as critical.
  • names – the GeneralNames for the subject.
Throws:
/**
     * Create a SubjectAlternativeNameExtension with the specified
     * criticality and GeneralNames.
     *
     * @param critical true if the extension is to be treated as critical.
     * @param names the GeneralNames for the subject.
     * @exception IOException on error.
     */
    public SubjectAlternativeNameExtension(Boolean critical, GeneralNames names)
    throws IOException {
        this.names = names;
        this.extensionId = PKIXExtensions.SubjectAlternativeName_Id;
        this.critical = critical.booleanValue();
        encodeThis();
    }

    
Create a default SubjectAlternativeNameExtension. The extension
is marked non-critical.

/**
     * Create a default SubjectAlternativeNameExtension. The extension
     * is marked non-critical.
     */
    public SubjectAlternativeNameExtension() {
        extensionId = PKIXExtensions.SubjectAlternativeName_Id;
        critical = false;
        names = new GeneralNames();
    }

    
Create the extension from the passed DER encoded value.

Params:
  • critical – true if the extension is to be treated as critical.
  • value – an array of DER encoded bytes of the actual value.
Throws:
/**
     * Create the extension from the passed DER encoded value.
     *
     * @param critical true if the extension is to be treated as critical.
     * @param value an array of DER encoded bytes of the actual value.
     * @exception ClassCastException if value is not an array of bytes
     * @exception IOException on error.
     */
    public SubjectAlternativeNameExtension(Boolean critical, Object value)
    throws IOException {
        this.extensionId = PKIXExtensions.SubjectAlternativeName_Id;
        this.critical = critical.booleanValue();

        this.extensionValue = (byte[]) value;
        DerValue val = new DerValue(this.extensionValue);
        if (val.data == null) {
            names = new GeneralNames();
            return;
        }

        names = new GeneralNames(val);
    }

    
Returns a printable representation of the SubjectAlternativeName.

/**
     * Returns a printable representation of the SubjectAlternativeName.
     */
    public String toString() {

        String result = super.toString() + "SubjectAlternativeName [\n";
        if(names == null) {
            result += "  null\n";
        } else {
            for(GeneralName name: names.names()) {
                result += "  "+name+"\n";
            }
        }
        result += "]\n";
        return result;
    }

    
Write the extension to the OutputStream.

Params:
  • out – the OutputStream to write the extension to.
Throws:
/**
     * Write the extension to the OutputStream.
     *
     * @param out the OutputStream to write the extension to.
     * @exception IOException on encoding errors.
     */
    public void encode(OutputStream out) throws IOException {
        DerOutputStream tmp = new DerOutputStream();
        if (extensionValue == null) {
            extensionId = PKIXExtensions.SubjectAlternativeName_Id;
            critical = false;
            encodeThis();
        }
        super.encode(tmp);
        out.write(tmp.toByteArray());
    }

    
Set the attribute value.

/**
     * Set the attribute value.
     */
    public void set(String name, Object obj) throws IOException {
        if (name.equalsIgnoreCase(SUBJECT_NAME)) {
            if (!(obj instanceof GeneralNames)) {
              throw new IOException("Attribute value should be of " +
                                    "type GeneralNames.");
            }
            names = (GeneralNames)obj;
        } else {
          throw new IOException("Attribute name not recognized by " +
                        "CertAttrSet:SubjectAlternativeName.");
        }
        encodeThis();
    }

    
Get the attribute value.

/**
     * Get the attribute value.
     */
    public GeneralNames get(String name) throws IOException {
        if (name.equalsIgnoreCase(SUBJECT_NAME)) {
            return (names);
        } else {
          throw new IOException("Attribute name not recognized by " +
                        "CertAttrSet:SubjectAlternativeName.");
        }
    }

    
Delete the attribute value.

/**
     * Delete the attribute value.
     */
    public void delete(String name) throws IOException {
        if (name.equalsIgnoreCase(SUBJECT_NAME)) {
            names = null;
        } else {
          throw new IOException("Attribute name not recognized by " +
                        "CertAttrSet:SubjectAlternativeName.");
        }
        encodeThis();
    }

    
Return an enumeration of names of attributes existing within this
attribute.

/**
     * Return an enumeration of names of attributes existing within this
     * attribute.
     */
    public Enumeration<String> getElements() {
        AttributeNameEnumeration elements = new AttributeNameEnumeration();
        elements.addElement(SUBJECT_NAME);

        return (elements.elements());
    }

    
Return the name of this attribute.

/**
     * Return the name of this attribute.
     */
    public String getName() {
        return (NAME);
    }
}