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package com.sun.security.sasl;

import javax.security.sasl.*;

Implements the EXTERNAL SASL client mechanism.
(RFC 2222).
The EXTERNAL mechanism returns the optional authorization ID as
the initial response. It processes no challenges.
Author:
Rosanna Lee/**
  * Implements the EXTERNAL SASL client mechanism.
  * (<A HREF="http://www.ietf.org/rfc/rfc2222.txt">RFC 2222</A>).
  * The EXTERNAL mechanism returns the optional authorization ID as
  * the initial response. It processes no challenges.
  *
  * @author Rosanna Lee
  */
final class ExternalClient implements SaslClient {
    private byte[] username;
    private boolean completed = false;

    
Constructs an External mechanism with optional authorization ID.
Params:
authorizationID – If non-null, used to specify authorization ID.
Throws:
SaslException – if cannot convert authorizationID into UTF-8
    representation./**
     * Constructs an External mechanism with optional authorization ID.
     *
     * @param authorizationID If non-null, used to specify authorization ID.
     * @throws SaslException if cannot convert authorizationID into UTF-8
     *     representation.
     */
    ExternalClient(String authorizationID) throws SaslException {
        if (authorizationID != null) {
            try {
                username = authorizationID.getBytes("UTF8");
            } catch (java.io.UnsupportedEncodingException e) {
                throw new SaslException("Cannot convert " + authorizationID +
                    " into UTF-8", e);
            }
        } else {
            username = new byte[0];
        }
    }

    
Retrieves this mechanism's name for initiating the "EXTERNAL" protocol
exchange.
Returns:
 The string "EXTERNAL"./**
     * Retrieves this mechanism's name for initiating the "EXTERNAL" protocol
     * exchange.
     *
     * @return  The string "EXTERNAL".
     */
    public String getMechanismName() {
        return "EXTERNAL";
    }

    
This mechanism has an initial response.
/**
     * This mechanism has an initial response.
     */
    public boolean hasInitialResponse() {
        return true;
    }

    public void dispose() throws SaslException {
    }

    
Processes the challenge data.
It returns the EXTERNAL mechanism's initial response,
which is the authorization id encoded in UTF-8.
This is the optional information that is sent along with the SASL command.
After this method is called, isComplete() returns true.
Params:
challengeData – Ignored.
Throws:
SaslException – If authentication has already been called.
Returns:
The possible empty initial response./**
     * Processes the challenge data.
     * It returns the EXTERNAL mechanism's initial response,
     * which is the authorization id encoded in UTF-8.
     * This is the optional information that is sent along with the SASL command.
     * After this method is called, isComplete() returns true.
     *
     * @param challengeData Ignored.
     * @return The possible empty initial response.
     * @throws SaslException If authentication has already been called.
     */
    public byte[] evaluateChallenge(byte[] challengeData)
        throws SaslException {
        if (completed) {
            throw new IllegalStateException(
                "EXTERNAL authentication already completed");
        }
        completed = true;
        return username;
    }

    
Returns whether this mechanism is complete.
Returns:
true if initial response has been sent; false otherwise./**
     * Returns whether this mechanism is complete.
     * @return true if initial response has been sent; false otherwise.
     */
    public boolean isComplete() {
        return completed;
    }

    
Unwraps the incoming buffer.
Throws:
SaslException – Not applicable to this mechanism./**
      * Unwraps the incoming buffer.
      *
      * @throws SaslException Not applicable to this mechanism.
      */
    public byte[] unwrap(byte[] incoming, int offset, int len)
        throws SaslException {
        if (completed) {
            throw new SaslException("EXTERNAL has no supported QOP");
        } else {
            throw new IllegalStateException(
                "EXTERNAL authentication Not completed");
        }
    }

    
Wraps the outgoing buffer.
Throws:
SaslException – Not applicable to this mechanism./**
      * Wraps the outgoing buffer.
      *
      * @throws SaslException Not applicable to this mechanism.
      */
    public byte[] wrap(byte[] outgoing, int offset, int len)
        throws SaslException {
        if (completed) {
            throw new SaslException("EXTERNAL has no supported QOP");
        } else {
            throw new IllegalStateException(
                "EXTERNAL authentication not completed");
        }
    }

    
Retrieves the negotiated property. This method can be called only after the authentication exchange has completed (i.e., when isComplete() returns true); otherwise, a IllegalStateException is thrown. 
Throws:
IllegalStateException – if this authentication exchange
has not completed
Returns:
null No property is applicable to this mechanism./**
     * Retrieves the negotiated property.
     * This method can be called only after the authentication exchange has
     * completed (i.e., when {@code isComplete()} returns true); otherwise, a
     * {@code IllegalStateException} is thrown.
     *
     * @return null No property is applicable to this mechanism.
     * @exception IllegalStateException if this authentication exchange
     * has not completed
     */
    public Object getNegotiatedProperty(String propName) {
        if (completed) {
            return null;
        } else {
            throw new IllegalStateException(
                "EXTERNAL authentication not completed");
        }
    }
}