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package com.sun.jndi.ldap.sasl;

import javax.security.auth.callback.*;
import javax.security.sasl.RealmCallback;
import javax.security.sasl.RealmChoiceCallback;
import java.io.IOException;

DefaultCallbackHandler for satisfying NameCallback and
PasswordCallback for an LDAP client.
NameCallback is used for getting the authentication ID and is
gotten from the java.naming.security.principal property.
PasswordCallback is gotten from the java.naming.security.credentials
property and must be of type String, char[] or byte[].
If byte[], it is assumed to have UTF-8 encoding.
If the caller of getPassword() will be using the password as
a byte array, then it should encode the char[] array returned by
getPassword() into a byte[] using UTF-8.
Author:
Rosanna Lee/**
 * DefaultCallbackHandler for satisfying NameCallback and
 * PasswordCallback for an LDAP client.
 * NameCallback is used for getting the authentication ID and is
 * gotten from the java.naming.security.principal property.
 * PasswordCallback is gotten from the java.naming.security.credentials
 * property and must be of type String, char[] or byte[].
 * If byte[], it is assumed to have UTF-8 encoding.
 *
 * If the caller of getPassword() will be using the password as
 * a byte array, then it should encode the char[] array returned by
 * getPassword() into a byte[] using UTF-8.
 *
 * @author Rosanna Lee
 */
final class DefaultCallbackHandler implements CallbackHandler {
    private char[] passwd;
    private String authenticationID;
    private String authRealm;

    DefaultCallbackHandler(String principal, Object cred, String realm)
        throws IOException {
        authenticationID = principal;
        authRealm = realm;
        if (cred instanceof String) {
            passwd = ((String)cred).toCharArray();
        } else if (cred instanceof char[]) {
            passwd = ((char[])cred).clone();
        } else if (cred != null) {
            // assume UTF-8 encoding
            String orig = new String((byte[])cred, "UTF8");
            passwd = orig.toCharArray();
        }
    }

    public void handle(Callback[] callbacks)
        throws IOException, UnsupportedCallbackException {
            for (int i = 0; i < callbacks.length; i++) {
                if (callbacks[i] instanceof NameCallback) {
                    ((NameCallback)callbacks[i]).setName(authenticationID);

                } else if (callbacks[i] instanceof PasswordCallback) {
                    ((PasswordCallback)callbacks[i]).setPassword(passwd);

                } else if (callbacks[i] instanceof RealmChoiceCallback) {
                    /* Deals with a choice of realms */
                    String[] choices =
                        ((RealmChoiceCallback)callbacks[i]).getChoices();
                    int selected = 0;

                    if (authRealm != null && authRealm.length() > 0) {
                        selected = -1; // no realm chosen
                        for (int j = 0; j < choices.length; j++) {
                            if (choices[j].equals(authRealm)) {
                                selected = j;
                            }
                        }
                        if (selected == -1) {
                            StringBuilder allChoices = new StringBuilder();
                            for (int j = 0; j <  choices.length; j++) {
                                allChoices.append(choices[j]).append(',');
                            }
                            throw new IOException("Cannot match " +
                                "'java.naming.security.sasl.realm' property value, '" +
                                authRealm + "' with choices " + allChoices +
                                "in RealmChoiceCallback");
                        }
                    }

                    ((RealmChoiceCallback)callbacks[i]).setSelectedIndex(selected);

                } else if (callbacks[i] instanceof RealmCallback) {
                    /* 1 or 0 realms specified in challenge */
                    RealmCallback rcb = (RealmCallback) callbacks[i];
                    if (authRealm != null) {
                        rcb.setText(authRealm);  // Use what user supplied
                    } else {
                        String defaultRealm = rcb.getDefaultText();
                        if (defaultRealm != null) {
                            rcb.setText(defaultRealm); // Use what server supplied
                        } else {
                            rcb.setText("");  // Specify no realm
                        }
                    }
                } else {
                    throw new UnsupportedCallbackException(callbacks[i]);
                }
            }
    }

    void clearPassword() {
        if (passwd != null) {
            for (int i = 0; i < passwd.length; i++) {
                passwd[i] = '\0';
            }
            passwd = null;
        }
    }

    @SuppressWarnings("deprecation")
    protected void finalize() throws Throwable {
        clearPassword();
    }
}