/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.wss4j.dom.message;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.time.Instant;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.util.Collections;

import javax.security.auth.callback.Callback;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.callback.UnsupportedCallbackException;

import org.apache.wss4j.common.bsp.BSPEnforcer;
import org.apache.wss4j.common.bsp.BSPRule;
import org.apache.wss4j.common.ext.WSPasswordCallback;
import org.apache.wss4j.common.ext.WSSecurityException;
import org.apache.wss4j.common.util.*;
import org.apache.wss4j.dom.WSConstants;
import org.apache.wss4j.dom.common.CustomHandler;
import org.apache.wss4j.dom.common.EncodedPasswordCallbackHandler;

import org.apache.wss4j.dom.common.UsernamePasswordCallbackHandler;
import org.apache.wss4j.dom.engine.WSSecurityEngine;
import org.apache.wss4j.dom.engine.WSSecurityEngineResult;
import org.apache.wss4j.dom.handler.HandlerAction;
import org.apache.wss4j.dom.handler.RequestData;
import org.apache.wss4j.dom.handler.WSHandlerConstants;
import org.apache.wss4j.dom.handler.WSHandlerResult;
import org.apache.wss4j.dom.message.token.UsernameToken;

import org.junit.jupiter.api.Test;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.fail;

/**
 * WS-Security Test Case for UsernameTokens.
 */
public class UsernameTokenTest implements CallbackHandler {
    private static final org.slf4j.Logger LOG =
        org.slf4j.LoggerFactory.getLogger(UsernameTokenTest.class);
    private static final String SOAPUTMSG =
        "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
        + "<SOAP-ENV:Envelope xmlns:SOAP-ENV=\"http://schemas.xmlsoap.org/soap/envelope/\" "
        + "xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" "
        + "xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\">"
        + "<SOAP-ENV:Header>"
        + "<wsse:Security SOAP-ENV:mustUnderstand=\"1\" "
        + "xmlns:wsse=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd\">"
        + "<wsse:UsernameToken wsu:Id=\"UsernameToken-29477163\" xmlns:wsu=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd\">"
        + "<wsse:Username>wernerd</wsse:Username>"
        + "<wsse:Password>verySecret</wsse:Password>"
        + "</wsse:UsernameToken></wsse:Security></SOAP-ENV:Header>"
        + "<SOAP-ENV:Body>"
        + "<add xmlns=\"http://ws.apache.org/counter/counter_port_type\">"
        + "<value xmlns=\"\">15</value>" + "</add>"
        + "</SOAP-ENV:Body>\r\n       \r\n" + "</SOAP-ENV:Envelope>";
    private static final String SOAPUTNOUSERMSG =
        "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
        + "<SOAP-ENV:Envelope xmlns:SOAP-ENV=\"http://schemas.xmlsoap.org/soap/envelope/\" "
        + "xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" "
        + "xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\">"
        + "<SOAP-ENV:Header>"
        + "<wsse:Security SOAP-ENV:mustUnderstand=\"1\" "
        + "xmlns:wsse=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd\">"
        + "<wsse:UsernameToken wsu:Id=\"UsernameToken-29477163\" xmlns:wsu=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd\">"
        + "<wsse:Username></wsse:Username>"
        + "<wsse:Password Type=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText\"></wsse:Password>"
        + "</wsse:UsernameToken></wsse:Security></SOAP-ENV:Header>"
        + "<SOAP-ENV:Body>"
        + "<add xmlns=\"http://ws.apache.org/counter/counter_port_type\">"
        + "<value xmlns=\"\">15</value>" + "</add>"
        + "</SOAP-ENV:Body>\r\n       \r\n" + "</SOAP-ENV:Envelope>";
    private static final String EMPTY_PASSWORD_MSG =
        "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
        + "<SOAP-ENV:Envelope xmlns:SOAP-ENV=\"http://schemas.xmlsoap.org/soap/envelope/\" "
        + "xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" "
        + "xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\">"
        + "<SOAP-ENV:Header>"
        + "<wsse:Security SOAP-ENV:mustUnderstand=\"1\" "
        + "xmlns:wsse=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd\">"
        + "<wsse:UsernameToken wsu:Id=\"UsernameToken-1\" "
        + "xmlns:wsse=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd\" "
        + "xmlns:wsu=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd\">"
        + "<wsse:Username>emptyuser</wsse:Username>"
        + "<wsse:Password Type=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText\"/>"
        + "</wsse:UsernameToken></wsse:Security></SOAP-ENV:Header>"
        + "<SOAP-ENV:Body>"
        + "<add xmlns=\"http://ws.apache.org/counter/counter_port_type\">"
        + "<value xmlns=\"\">15</value>" + "</add>"
        + "</SOAP-ENV:Body>\r\n       \r\n" + "</SOAP-ENV:Envelope>";

    private CallbackHandler callbackHandler = new UsernamePasswordCallbackHandler();

    /**
     * Test that adds a UserNameToken with password Digest to a WS-Security envelope
     */
    @Test
    public void testUsernameTokenDigest() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setUserInfo("wernerd", "verySecret");
        LOG.info("Before adding UsernameToken PW Digest....");
        Document signedDoc = builder.build();

        if (LOG.isDebugEnabled()) {
            LOG.debug("Message with UserNameToken PW Digest:");
            String outputString =
                XMLUtils.prettyDocumentToString(signedDoc);
            LOG.debug(outputString);
        }
        LOG.info("After adding UsernameToken PW Digest....");

        WSHandlerResult results = verify(signedDoc);
        WSSecurityEngineResult actionResult =
            results.getActionResults().get(WSConstants.UT).get(0);
        UsernameToken receivedToken =
            (UsernameToken) actionResult.get(WSSecurityEngineResult.TAG_USERNAME_TOKEN);
        assertNotNull(receivedToken);

        UsernameToken clone =
            new UsernameToken(receivedToken.getElement(), false, new BSPEnforcer());
        assertTrue(clone.equals(receivedToken));
        assertTrue(clone.hashCode() == receivedToken.hashCode());
    }

    /**
     * Test for encoded passwords.
     */
    @Test
    public void testUsernameTokenWithEncodedPasswordBaseline() throws Exception {
        String password = "password";
        // The SHA-1 of the password is known as a password equivalent in the UsernameToken specification.
        byte[] passwordHash = MessageDigest.getInstance("SHA-1").digest(password.getBytes(StandardCharsets.UTF_8));

        String nonce = "0x7bXAPZVn40AdCD0Xbt0g==";
        String created = "2010-06-28T15:16:37Z";
        String expectedPasswordDigest = "C0rena/6gKpRZ9ATj+e6ss5sAbQ=";
        byte[] decodedNonce = org.apache.xml.security.utils.XMLUtils.decode(nonce);
        String actualPasswordDigest = UsernameTokenUtil.doPasswordDigest(decodedNonce, created, passwordHash);
        assertEquals(expectedPasswordDigest, actualPasswordDigest, "the password digest is not as expected");
    }

    /**
     * Test that adds a UserNameToken with password Digest to a WS-Security envelope
     */
    @Test
    public void testUsernameTokenWithEncodedPassword() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordsAreEncoded(true);
        byte[] bytes = MessageDigest.getInstance("SHA-1").digest("verySecret".getBytes(StandardCharsets.UTF_8));
        builder.setUserInfo("wernerd", org.apache.xml.security.utils.XMLUtils.encodeToString(bytes));
        LOG.info("Before adding UsernameToken PW Digest....");
        Document signedDoc = builder.build();

        if (LOG.isDebugEnabled()) {
            LOG.debug("Message with UserNameToken PW Digest:");
            String outputString =
                XMLUtils.prettyDocumentToString(signedDoc);
            LOG.debug(outputString);
        }
        LOG.info("After adding UsernameToken PW Digest....");

        WSSecurityEngine newEngine = new WSSecurityEngine();
        RequestData requestData = new RequestData();
        requestData.setEncodePasswords(true);
        requestData.setCallbackHandler(new EncodedPasswordCallbackHandler());
        newEngine.processSecurityHeader(signedDoc, requestData);
    }

    /**
     * Test that a bad username with password digest does not leak whether the username
     * is valid or not - see WSS-141.
     */
    @Test
    public void testUsernameTokenBadUsername() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setUserInfo("badusername", "verySecret");
        LOG.info("Before adding UsernameToken PW Digest....");
        Document signedDoc = builder.build();

        if (LOG.isDebugEnabled()) {
            LOG.debug("Message with UserNameToken PW Digest:");
            String outputString =
                XMLUtils.prettyDocumentToString(signedDoc);
            LOG.debug(outputString);
        }
        LOG.info("After adding UsernameToken PW Digest....");
        try {
            verify(signedDoc);
            fail("Failure expected on a bad username");
        } catch (WSSecurityException ex) {
            String message = ex.getMessage();
            assertFalse(message.contains("badusername"));
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.FAILED_AUTHENTICATION);
            // expected
        }
    }

    /**
     * Test that adds a UserNameToken with a bad password Digest to a WS-Security envelope
     */
    @Test
    public void testUsernameTokenBadDigest() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setUserInfo("wernerd", "verySecre");
        LOG.info("Before adding UsernameToken PW Digest....");
        Document signedDoc = builder.build();

        if (LOG.isDebugEnabled()) {
            LOG.debug("Message with UserNameToken PW Digest:");
            String outputString =
                XMLUtils.prettyDocumentToString(signedDoc);
            LOG.debug(outputString);
        }
        LOG.info("After adding UsernameToken PW Digest....");
        try {
            verify(signedDoc);
            fail("Failure expected on a bad password digest");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.FAILED_AUTHENTICATION);
            // expected
        }
    }

    /**
     * This is a test for processing an "old" UsernameToken, i.e. one with a "Created" element that is
     * out of date
     */
    @Test
    public void testOldUsernameToken() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setUserInfo("wernerd", "verySecret");
        Document signedDoc = builder.build();

        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(signedDoc);
            LOG.debug(outputString);
        }

        RequestData requestData = new RequestData();
        requestData.setUtTTL(-1);
        requestData.setCallbackHandler(callbackHandler);

        try {
            WSSecurityEngine secEngine = new WSSecurityEngine();
            secEngine.processSecurityHeader(doc, requestData);
            fail("The UsernameToken validation should have failed");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.MESSAGE_EXPIRED);
        }
    }

    /**
     * This is a test for processing a UsernameToken where the "Created" element is in the (near)
     * future. It should be accepted by default when it is created 30 seconds in the future,
     * and then rejected once we configure "0 seconds" for future-time-to-live.
     */
    @Test
    public void testNearFutureCreated() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        Element usernameTokenElement =
            doc.createElementNS(
                WSConstants.WSSE_NS, WSConstants.WSSE_PREFIX + ":" + WSConstants.USERNAME_TOKEN_LN
            );
        Element usernameElement =
            doc.createElementNS(
                WSConstants.WSSE_NS, WSConstants.WSSE_PREFIX + ":" + WSConstants.USERNAME_LN
            );
        usernameElement.appendChild(doc.createTextNode("wernerd"));
        usernameTokenElement.appendChild(usernameElement);

        Element passwordElement =
            doc.createElementNS(
                WSConstants.WSSE_NS, WSConstants.WSSE_PREFIX + ":" + WSConstants.PASSWORD_LN
            );
        passwordElement.setAttributeNS(null, "Type", WSConstants.PASSWORD_TEXT);
        passwordElement.appendChild(doc.createTextNode("verySecret"));
        usernameTokenElement.appendChild(passwordElement);

        Element elementCreated =
            doc.createElementNS(
                WSConstants.WSU_NS, WSConstants.WSU_PREFIX + ":" + WSConstants.CREATED_LN
            );
        ZonedDateTime now = ZonedDateTime.now(ZoneOffset.UTC).plusSeconds(30L);
        elementCreated.appendChild(doc.createTextNode(DateUtil.getDateTimeFormatter(true).format(now)));
        usernameTokenElement.appendChild(elementCreated);

        secHeader.getSecurityHeaderElement().appendChild(usernameTokenElement);

        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(doc);
            LOG.debug(outputString);
        }

        // This should work
        WSSecurityEngine secEngine = new WSSecurityEngine();
        secEngine.processSecurityHeader(doc, null, callbackHandler, null);

        // This should not
        try {
            RequestData requestData = new RequestData();
            requestData.setUtFutureTTL(0);
            requestData.setCallbackHandler(callbackHandler);

            secEngine.processSecurityHeader(doc, requestData);
            fail("The UsernameToken validation should have failed");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.MESSAGE_EXPIRED);
        }
    }

    /**
     * This is a test for processing a UsernameToken where the "Created" element is in the future.
     * A UsernameToken that is 120 seconds in the future should be rejected by default.
     */
    @Test
    public void testFutureCreated() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        Element usernameTokenElement =
            doc.createElementNS(
                WSConstants.WSSE_NS, WSConstants.WSSE_PREFIX + ":" + WSConstants.USERNAME_TOKEN_LN
            );
        Element usernameElement =
            doc.createElementNS(
                WSConstants.WSSE_NS, WSConstants.WSSE_PREFIX + ":" + WSConstants.USERNAME_LN
            );
        usernameElement.appendChild(doc.createTextNode("wernerd"));
        usernameTokenElement.appendChild(usernameElement);

        Element passwordElement =
            doc.createElementNS(
                WSConstants.WSSE_NS, WSConstants.WSSE_PREFIX + ":" + WSConstants.PASSWORD_LN
            );
        passwordElement.setAttributeNS(null, "Type", WSConstants.PASSWORD_TEXT);
        passwordElement.appendChild(doc.createTextNode("verySecret"));
        usernameTokenElement.appendChild(passwordElement);

        Element elementCreated =
            doc.createElementNS(
                WSConstants.WSU_NS, WSConstants.WSU_PREFIX + ":" + WSConstants.CREATED_LN
            );
        ZonedDateTime now = ZonedDateTime.now(ZoneOffset.UTC).plusSeconds(120L);
        elementCreated.appendChild(doc.createTextNode(DateUtil.getDateTimeFormatter(true).format(now)));
        usernameTokenElement.appendChild(elementCreated);

        secHeader.getSecurityHeaderElement().appendChild(usernameTokenElement);

        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(doc);
            LOG.debug(outputString);
        }

        try {
            WSSecurityEngine secEngine = new WSSecurityEngine();
            secEngine.processSecurityHeader(doc, null, callbackHandler, null);
            fail("The UsernameToken validation should have failed");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.MESSAGE_EXPIRED);
        }
    }

    /**
     * Test that adds a UserNameToken with password text to a WS-Security envelope
     */
    @Test
    public void testUsernameTokenText() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordType(WSConstants.PASSWORD_TEXT);
        builder.setUserInfo("wernerd", "verySecret");
        LOG.info("Before adding UsernameToken PW Text....");
        Document signedDoc = builder.build();
        if (LOG.isDebugEnabled()) {
            LOG.debug("Message with UserNameToken PW Text:");
            String outputString =
                XMLUtils.prettyDocumentToString(signedDoc);
            LOG.debug(outputString);
        }
        LOG.info("After adding UsernameToken PW Text....");

        WSHandlerResult results = verify(signedDoc);
        WSSecurityEngineResult actionResult =
            results.getActionResults().get(WSConstants.UT).get(0);
        UsernameToken receivedToken =
            (UsernameToken) actionResult.get(WSSecurityEngineResult.TAG_USERNAME_TOKEN);
        assertNotNull(receivedToken);

        UsernameToken clone =
            new UsernameToken(receivedToken.getElement(), false, new BSPEnforcer());
        assertTrue(clone.equals(receivedToken));
        assertTrue(clone.hashCode() == receivedToken.hashCode());
    }

    /**
     * Test that adds a UserNameToken with a digested password but with type of
     * password test.
     */
    @Test
    public void testUsernameTokenDigestText() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordType(WSConstants.PASSWORD_TEXT);
        byte[] password = "verySecret".getBytes();
        MessageDigest sha = MessageDigest.getInstance("MD5");
        sha.reset();
        sha.update(password);
        String passwdDigest = org.apache.xml.security.utils.XMLUtils.encodeToString(sha.digest());

        builder.setUserInfo("wernerd", passwdDigest);
        LOG.info("Before adding UsernameToken PW Text....");
        Document signedDoc = builder.build();
        if (LOG.isDebugEnabled()) {
            LOG.debug("Message with UserNameToken PW Text:");
            String outputString =
                XMLUtils.prettyDocumentToString(signedDoc);
            LOG.debug(outputString);
        }
    }

    /**
     * Test that adds a UserNameToken with (bad) password text to a WS-Security envelope
     */
    @Test
    public void testUsernameTokenBadText() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordType(WSConstants.PASSWORD_TEXT);
        builder.setUserInfo("wernerd", "verySecre");
        LOG.info("Before adding UsernameToken PW Text....");
        Document signedDoc = builder.build();
        if (LOG.isDebugEnabled()) {
            LOG.debug("Message with UserNameToken PW Text:");
            String outputString =
                XMLUtils.prettyDocumentToString(signedDoc);
            LOG.debug(outputString);
        }
        LOG.info("After adding UsernameToken PW Text....");

        try {
            verify(signedDoc);
            fail("Failure expected on a bad password text");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.FAILED_AUTHENTICATION);
            // expected
        }
    }

    /**
     * Test that adds a UserNameToken with no password type to a WS-Security envelope
     * See WSS-152 - https://issues.apache.org/jira/browse/WSS-152
     * "Problem with processing Username Tokens with no password type"
     * The 1.1 spec states that the password type is optional and defaults to password text,
     * and so we should handle an incoming Username Token accordingly.
     */
    @Test
    public void testUsernameTokenNoPasswordType() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUTMSG);
        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(doc);
            LOG.debug(outputString);
        }

        WSSecurityEngine newEngine = new WSSecurityEngine();
        try {
            newEngine.processSecurityHeader(doc, null, callbackHandler, null);
            fail("Expected failure as it is not BSP compliant");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.INVALID_SECURITY);
        }
        RequestData data = new RequestData();
        data.setCallbackHandler(callbackHandler);
        data.setIgnoredBSPRules(Collections.singletonList(BSPRule.R4201));
        newEngine.processSecurityHeader(doc, data);
    }

    /**
     * Test that adds a UserNameToken with no user (or password) to a WS-Security envelope
     * See WSS-185 - https://issues.apache.org/jira/browse/WSS-185
     * "NullPointerException on empty UsernameToken"
     */
    @Test
    public void testUsernameTokenNoUser() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUTNOUSERMSG);
        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(doc);
            LOG.debug(outputString);
        }
        try {
            verify(doc);
            fail("Failure expected on no password");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.FAILED_AUTHENTICATION);
            // expected
        }
    }

    /**
     * Test that adds a UserNameToken with no password
     */
    @Test
    public void testUsernameTokenNoPassword() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordType(null);
        builder.setUserInfo("nopassuser", null);
        LOG.info("Before adding UsernameToken with no password....");
        Document signedDoc = builder.build();
        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(signedDoc);
            LOG.debug(outputString);
        }

        WSHandlerResult results = verify(signedDoc, true);
        WSSecurityEngineResult actionResult =
            results.getActionResults().get(WSConstants.UT_NOPASSWORD).get(0);
        UsernameToken receivedToken =
            (UsernameToken) actionResult.get(WSSecurityEngineResult.TAG_USERNAME_TOKEN);
        assertNotNull(receivedToken);
    }

    /**
     * Test that adds a UserNameToken with an empty password
     */
    @Test
    public void testUsernameTokenEmptyPassword() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordType(WSConstants.PASSWORD_TEXT);
        builder.setUserInfo("emptyuser", "");
        LOG.info("Before adding UsernameToken with an empty password....");
        Document signedDoc = builder.build();
        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(signedDoc);
            LOG.debug(outputString);
        }
        WSSecurityEngine secEngine = new WSSecurityEngine();
        secEngine.processSecurityHeader(doc, null, this, null);
    }

    /**
     * Test that processes a UserNameToken with an empty password
     */
    @Test
    public void testEmptyPasswordProcessing() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(EMPTY_PASSWORD_MSG);
        if (LOG.isDebugEnabled()) {
            LOG.debug("Empty password message: ");
            String outputString =
                XMLUtils.prettyDocumentToString(doc);
            LOG.debug(outputString);
        }

        WSSecurityEngine secEngine = new WSSecurityEngine();
        secEngine.processSecurityHeader(doc, null, this, null);
    }

    /**
     * Test with a non-standard token type. This will fail as the default is to reject custom
     * token types.
     */
    @Test
    public void testUsernameTokenCustomFail() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordType("RandomType");
        builder.setUserInfo("wernerd", "verySecret");

        Document signedDoc = builder.build();

        if (LOG.isDebugEnabled()) {
            LOG.debug("Message with UserNameToken PW Text:");
            String outputString =
                XMLUtils.prettyDocumentToString(signedDoc);
            LOG.debug(outputString);
        }
        try {
            WSSecurityEngine secEngine = new WSSecurityEngine();
            secEngine.processSecurityHeader(signedDoc, null, this, null);
            fail("Custom token types are not permitted");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.FAILED_AUTHENTICATION);
            // expected
        }
    }

    /**
     * Test with a non-standard password type. This will pass as the WSSConfig is configured to
     * handle custom token types.
     */
    @Test
    public void testUsernameTokenCustomPass() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordType("RandomType");
        builder.setUserInfo("wernerd", "verySecret");

        Document signedDoc = builder.build();

        if (LOG.isDebugEnabled()) {
            LOG.debug("Message with UserNameToken PW custom type:");
            String outputString =
                XMLUtils.prettyDocumentToString(signedDoc);
            LOG.debug(outputString);
        }

        //
        // Configure so that custom token types are accepted
        //
        WSSecurityEngine secEngine = new WSSecurityEngine();

        RequestData requestData = new RequestData();
        requestData.setHandleCustomPasswordTypes(true);
        requestData.setCallbackHandler(callbackHandler);

        secEngine.processSecurityHeader(doc, requestData);
    }


    /**
     * A test for WSS-66 - the nonce string is null
     * http://issues.apache.org/jira/browse/WSS-66
     * "Possible security hole when PasswordDigest is used by client."
     */
    @Test
    public void testNullNonce() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordType(WSConstants.PASSWORD_DIGEST);
        builder.setUserInfo("wernerd", "BAD_PASSWORD");

        Document utDoc = builder.build();

        //
        // Manually find the Nonce node and set the content to null
        //
        Element elem = builder.getUsernameTokenElement();
        NodeList list = elem.getElementsByTagNameNS(WSConstants.WSSE_NS, "Nonce");
        Node nonceNode = list.item(0);
        Node childNode = nonceNode.getFirstChild();
        childNode.setNodeValue("");

        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(utDoc);
            LOG.debug(outputString);
        }

        try {
            //
            // Verification should fail as the password is bad
            //
            verify(utDoc);
            fail("Expected failure due to a bad password");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.FAILED_AUTHENTICATION);
            // expected
        }
    }

    /**
     * A test for WSS-66 - the created string is null
     * http://issues.apache.org/jira/browse/WSS-66
     * "Possible security hole when PasswordDigest is used by client."
     */
    @Test
    public void testNullCreated() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordType(WSConstants.PASSWORD_DIGEST);
        builder.setUserInfo("wernerd", "BAD_PASSWORD");

        Document utDoc = builder.build();
        //
        // Manually find the Created node and set the content to null
        //
        Element elem = builder.getUsernameTokenElement();
        NodeList list = elem.getElementsByTagNameNS(WSConstants.WSU_NS, "Created");
        Node nonceNode = list.item(0);
        Node childNode = nonceNode.getFirstChild();
        childNode.setNodeValue("");

        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(utDoc);
            LOG.debug(outputString);
        }

        try {
            //
            // Verification should fail as the password is bad
            //
            verify(utDoc);
            fail("Expected failure due to a bad password");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.FAILED_AUTHENTICATION);
            // expected
        }
    }

    /**
     * Test that verifies an EncodingType is set for the nonce. See WSS-169.
     */
    @Test
    public void testUsernameTokenNonceEncodingType() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setUserInfo("wernerd", "verySecret");
        LOG.info("Before adding UsernameToken PW Digest....");
        Document signedDoc = builder.build();
        String outputString =
            XMLUtils.prettyDocumentToString(signedDoc);
        assertTrue(outputString.contains("EncodingType"));
    }

    /**
     * Test that adds a UserNameToken via WSHandler
     */
    @Test
    public void testUsernameTokenWSHandler() throws Exception {
        CustomHandler handler = new CustomHandler();
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);

        RequestData reqData = new RequestData();
        java.util.Map<String, Object> config = new java.util.TreeMap<>();
        config.put("password", "verySecret");
        config.put(WSHandlerConstants.PASSWORD_TYPE, WSConstants.PW_TEXT);
        reqData.setUsername("wernerd");
        reqData.setMsgContext(config);

        HandlerAction action = new HandlerAction(WSConstants.UT);
        handler.send(
            doc,
            reqData,
            Collections.singletonList(action),
            true
        );

        if (LOG.isDebugEnabled()) {
            LOG.debug("Username Token via WSHandler");
            String outputString =
                XMLUtils.prettyDocumentToString(doc);
            LOG.debug(outputString);
        }
    }

    /**
     * Test that adds a UserNameToken with no password via WSHandler
     */
    @Test
    public void testUsernameTokenWSHandlerNoPassword() throws Exception {
        CustomHandler handler = new CustomHandler();
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);

        RequestData reqData = new RequestData();
        java.util.Map<String, Object> config = new java.util.TreeMap<>();
        config.put(WSHandlerConstants.PASSWORD_TYPE, WSConstants.PW_NONE);
        reqData.setUsername("wernerd");
        reqData.setMsgContext(config);

        HandlerAction action = new HandlerAction(WSConstants.UT);
        handler.send(
            doc,
            reqData,
            Collections.singletonList(action),
            true
        );

        if (LOG.isDebugEnabled()) {
            LOG.debug("Username Token via WSHandler");
            String outputString =
                XMLUtils.prettyDocumentToString(doc);
            LOG.debug(outputString);
        }
    }

    /**
     * Test that adds a UserNameToken with no password via WSHandler
     */
    @Test
    public void testUsernameTokenWSHandlerNoPassword2() throws Exception {
        CustomHandler handler = new CustomHandler();
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);

        RequestData reqData = new RequestData();
        java.util.Map<String, Object> config = new java.util.TreeMap<>();
        reqData.setUsername("wernerd");
        reqData.setMsgContext(config);

        HandlerAction action = new HandlerAction(WSConstants.UT_NOPASSWORD);
        handler.send(
            doc,
            reqData,
            Collections.singletonList(action),
            true
        );

        if (LOG.isDebugEnabled()) {
            LOG.debug("Username Token via WSHandler");
            String outputString =
                XMLUtils.prettyDocumentToString(doc);
            LOG.debug(outputString);
        }
    }

    /**
     * Test that adds a UserNameToken with an empty password via WSHandler
     */
    @Test
    public void testUsernameTokenWSHandlerEmptyPassword() throws Exception {
        CustomHandler handler = new CustomHandler();
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);

        RequestData reqData = new RequestData();
        java.util.Map<String, Object> config = new java.util.TreeMap<>();
        config.put(WSHandlerConstants.PASSWORD_TYPE, WSConstants.PW_TEXT);
        config.put(WSHandlerConstants.PW_CALLBACK_REF, this);
        reqData.setUsername("emptyuser");
        reqData.setMsgContext(config);

        HandlerAction action = new HandlerAction(WSConstants.UT);
        handler.send(
            doc,
            reqData,
            Collections.singletonList(action),
            true
        );

        if (LOG.isDebugEnabled()) {
            LOG.debug("Username Token with an empty password via WSHandler");
            String outputString =
                XMLUtils.prettyDocumentToString(doc);
            LOG.debug(outputString);
        }
    }

    /**
     * A test for sending multiple nonces in the UsernameToken
     */
    @Test
    public void testMultipleNonce() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordType(WSConstants.PASSWORD_DIGEST);
        builder.setUserInfo("wernerd", "verySecret");

        Document utDoc = builder.build();

        //
        // Manually find the Nonce node and duplicate it
        //
        Element elem = builder.getUsernameTokenElement();
        NodeList list = elem.getElementsByTagNameNS(WSConstants.WSSE_NS, "Nonce");
        Node nonceNode = list.item(0);
        Node nonceCopy = nonceNode.cloneNode(true);
        nonceNode.getParentNode().insertBefore(nonceCopy, nonceNode);

        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(utDoc);
            LOG.debug(outputString);
        }

        WSSecurityEngine newEngine = new WSSecurityEngine();
        try {
            newEngine.processSecurityHeader(doc, null, callbackHandler, null);
            fail("Expected failure as it is not BSP compliant");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.INVALID_SECURITY      );
        }

        RequestData data = new RequestData();
        data.setCallbackHandler(callbackHandler);
        data.setIgnoredBSPRules(Collections.singletonList(BSPRule.R4225));
        newEngine.processSecurityHeader(doc, data);
    }

    /**
     * A test for sending multiple Created elements in the UsernameToken
     */
    @Test
    public void testMultipleCreated() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordType(WSConstants.PASSWORD_DIGEST);
        builder.setUserInfo("wernerd", "verySecret");

        Document utDoc = builder.build();

        //
        // Manually find the Created node and duplicate it
        //
        Element elem = builder.getUsernameTokenElement();
        NodeList list = elem.getElementsByTagNameNS(WSConstants.WSU_NS, "Created");
        Node createdNode = list.item(0);
        Node createdCopy = createdNode.cloneNode(true);
        createdNode.getParentNode().insertBefore(createdCopy, createdNode);

        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(utDoc);
            LOG.debug(outputString);
        }

        WSSecurityEngine newEngine = new WSSecurityEngine();
        try {
            newEngine.processSecurityHeader(doc, null, callbackHandler, null);
            fail("Expected failure as it is not BSP compliant");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.INVALID_SECURITY);
        }

        RequestData data = new RequestData();
        data.setCallbackHandler(callbackHandler);
        data.setIgnoredBSPRules(Collections.singletonList(BSPRule.R4223));
        newEngine.processSecurityHeader(doc, data);
    }

    /**
     * A test for sending multiple passwords in the UsernameToken
     */
    @Test
    public void testMultiplePassword() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordType(WSConstants.PASSWORD_DIGEST);
        builder.setUserInfo("wernerd", "verySecret");

        Document utDoc = builder.build();

        //
        // Manually find the Nonce node and duplicate it
        //
        Element elem = builder.getUsernameTokenElement();
        NodeList list = elem.getElementsByTagNameNS(WSConstants.WSSE_NS, "Password");
        Node passwordNode = list.item(0);
        Node passwordCopy = passwordNode.cloneNode(true);
        passwordNode.getParentNode().insertBefore(passwordCopy, passwordNode);

        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(utDoc);
            LOG.debug(outputString);
        }

        WSSecurityEngine newEngine = new WSSecurityEngine();
        try {
            newEngine.processSecurityHeader(doc, null, callbackHandler, null);
            fail("Expected failure as it is not BSP compliant");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.INVALID_SECURITY);
        }

        RequestData data = new RequestData();
        data.setCallbackHandler(callbackHandler);
        data.setIgnoredBSPRules(Collections.singletonList(BSPRule.R4222));
        newEngine.processSecurityHeader(doc, data);
    }

    /**
     * A test for sending a nonce with a bad encoding type in the UsernameToken
     */
    @Test
    public void testNonceBadEncodingType() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setPasswordType(WSConstants.PASSWORD_DIGEST);
        builder.setUserInfo("wernerd", "verySecret");

        Document utDoc = builder.build();

        //
        // Manually find the Nonce node and duplicate it
        //
        Element elem = builder.getUsernameTokenElement();
        NodeList list = elem.getElementsByTagNameNS(WSConstants.WSSE_NS, "Nonce");
        Node nonceNode = list.item(0);
        ((Element)nonceNode).setAttributeNS(
            null, "EncodingType", "http://bad_encoding_type"
        );

        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(utDoc);
            LOG.debug(outputString);
        }

        WSSecurityEngine newEngine = new WSSecurityEngine();
        try {
            newEngine.processSecurityHeader(doc, null, callbackHandler, null);
            fail("Expected failure as it is not BSP compliant");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.INVALID_SECURITY);
        }

        RequestData data = new RequestData();
        data.setCallbackHandler(callbackHandler);
        data.setIgnoredBSPRules(Collections.singletonList(BSPRule.R4221));
        newEngine.processSecurityHeader(doc, data);
    }

    @Test
    public void testUsernameTokenWSHandlerNonceCreated() throws Exception {
        CustomHandler handler = new CustomHandler();
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);

        RequestData reqData = new RequestData();
        java.util.Map<String, Object> config = new java.util.TreeMap<>();
        config.put("password", "verySecret");
        config.put(WSHandlerConstants.PASSWORD_TYPE, WSConstants.PW_TEXT);
        config.put(WSHandlerConstants.ADD_USERNAMETOKEN_NONCE, "true");
        config.put(WSHandlerConstants.ADD_USERNAMETOKEN_CREATED, "true");
        reqData.setUsername("wernerd");
        reqData.setMsgContext(config);

        HandlerAction action = new HandlerAction(WSConstants.UT);
        handler.send(
            doc,
            reqData,
            Collections.singletonList(action),
            true
        );

        if (LOG.isDebugEnabled()) {
            LOG.debug("Username Token via WSHandler");
            String outputString =
                XMLUtils.prettyDocumentToString(doc);
            LOG.debug(outputString);
        }
    }

    /**
     * This is a test to create a "Spoofed" UsernameToken (see WSS-441)
     */
    @Test
    public void testSpoofedUsernameToken() throws Exception {
        Document doc = SOAPUtil.toSOAPPart(SOAPUtil.SAMPLE_SOAP_MSG);
        WSSecHeader secHeader = new WSSecHeader(doc);
        secHeader.insertSecurityHeader();

        WSSecUsernameToken builder = new WSSecUsernameToken(secHeader);
        builder.setUserInfo("wernerd", "verySecret");

        WSTimeSource spoofedTimeSource = new WSTimeSource() {

            public Instant now() {
                return Instant.now().minusSeconds(500L);
            }

        };

        builder.setWsTimeSource(spoofedTimeSource);
        Document signedDoc = builder.build();

        if (LOG.isDebugEnabled()) {
            String outputString =
                XMLUtils.prettyDocumentToString(signedDoc);
            LOG.debug(outputString);
        }

        try {
            WSSecurityEngine secEngine = new WSSecurityEngine();
            secEngine.processSecurityHeader(doc, null, callbackHandler, null);
            fail("The UsernameToken validation should have failed");
        } catch (WSSecurityException ex) {
            assertTrue(ex.getErrorCode() == WSSecurityException.ErrorCode.MESSAGE_EXPIRED);
        }
    }


    private WSHandlerResult verify(Document doc) throws Exception {
        return verify(doc, false);
    }

    /**
     * Verifies the soap envelope
     *
     * @param doc
     * @param allowUsernameTokenDerivedKeys
     * @throws Exception Thrown when there is a problem in verification
     */
    private WSHandlerResult verify(Document doc, boolean allowUsernameTokenDerivedKeys) throws Exception {
        WSSecurityEngine secEngine = new WSSecurityEngine();

        RequestData requestData = new RequestData();
        requestData.setAllowUsernameTokenNoPassword(allowUsernameTokenDerivedKeys);
        requestData.setCallbackHandler(callbackHandler);

        return secEngine.processSecurityHeader(doc, requestData);
    }

    /**
     * A CallbackHandler for some (mostly insecure) scenarios.
     */
    public void handle(Callback[] callbacks)
        throws IOException, UnsupportedCallbackException {
        for (Callback callback : callbacks) {
            if (callback instanceof WSPasswordCallback) {
                WSPasswordCallback pc = (WSPasswordCallback) callback;
                if (pc.getUsage() == WSPasswordCallback.USERNAME_TOKEN) {
                    if ("emptyuser".equals(pc.getIdentifier())) {
                        pc.setPassword("");
                    } else if ("customUser".equals(pc.getIdentifier())) {
                        return;
                    } else if (null == pc.getIdentifier()) {
                        // Note that this is not secure! Just doing this to test a NPE
                        return;
                    }
                }
            } else {
                throw new UnsupportedCallbackException(callback, "Unrecognized Callback");
            }
        }
    }
}