Program: 52302
Project: 52302
Buggy source:
/** 
 * Returns an AuthenticatedUser representing the user authenticated by the given credentials.
 * @param credentials The credentials to use for authentication.
 * @return An AuthenticatedUser representing the user authenticated by the given credentials.
 * @throws GuacamoleException If an error occurs while authenticating the user, or if access is denied.
 */
public AuthenticatedUser authenticateUser(Credentials credentials) throws GuacamoleException {
  HttpServletRequest request=credentials.getRequest();
  RadiusPacket radPack;
  if (credentials.getUsername() == null || credentials.getUsername().isEmpty())   return null;
  if (credentials.getPassword() == null || credentials.getPassword().isEmpty())   return null;
  String challengeResponse=request.getParameter(RadiusChallengeResponseField.PARAMETER_NAME);
  if (challengeResponse == null) {
    try {
      radPack=radiusService.authenticate(credentials.getUsername(),credentials.getPassword());
    }
 catch (    GuacamoleException e) {
      logger.error("String_Node_Str",e.getMessage());
      logger.debug("String_Node_Str",e);
      radPack=null;
    }
    if (radPack == null) {
      logger.debug("String_Node_Str");
      throw new GuacamoleInvalidCredentialsException("String_Node_Str",CredentialsInfo.USERNAME_PASSWORD);
    }
 else     if (radPack instanceof AccessReject) {
      logger.debug("String_Node_Str");
      throw new GuacamoleInvalidCredentialsException("String_Node_Str",CredentialsInfo.USERNAME_PASSWORD);
    }
 else     if (radPack instanceof AccessChallenge) {
      RadiusAttribute stateAttr=radPack.findAttribute(Attr_State.TYPE);
      if (stateAttr == null) {
        logger.error("String_Node_Str");
        logger.debug("String_Node_Str");
        throw new GuacamoleInvalidCredentialsException("String_Node_Str",CredentialsInfo.USERNAME_PASSWORD);
      }
      RadiusAttribute replyAttr=radPack.findAttribute(Attr_ReplyMessage.TYPE);
      if (replyAttr == null) {
        logger.error("String_Node_Str");
        logger.debug("String_Node_Str");
        throw new GuacamoleInvalidCredentialsException("String_Node_Str",CredentialsInfo.USERNAME_PASSWORD);
      }
      String replyMsg=replyAttr.toString();
      String radiusState=new String(stateAttr.getValue().getBytes());
      Field radiusResponseField=new RadiusChallengeResponseField(replyMsg);
      Field radiusStateField=new RadiusStateField(radiusState);
      CredentialsInfo expectedCredentials=new CredentialsInfo(Arrays.asList(radiusResponseField,radiusStateField));
      throw new GuacamoleInsufficientCredentialsException("String_Node_Str",expectedCredentials);
    }
 else     if (radPack instanceof AccessAccept) {
      try {
        AuthenticatedUser authenticatedUser=authenticatedUserProvider.get();
        authenticatedUser.init(credentials);
        return authenticatedUser;
      }
  finally {
        radiusService.disconnect();
      }
    }
 else     throw new GuacamoleInvalidCredentialsException("String_Node_Str",CredentialsInfo.USERNAME_PASSWORD);
  }
 else {
    try {
      radPack=radiusService.authenticate(credentials.getUsername(),request.getParameter(RadiusStateField.PARAMETER_NAME),challengeResponse);
    }
 catch (    GuacamoleException e) {
      logger.error("String_Node_Str",e.getMessage());
      logger.debug("String_Node_Str",e);
      radPack=null;
    }
 finally {
      radiusService.disconnect();
    }
    if (radPack instanceof AccessAccept) {
      AuthenticatedUser authenticatedUser=authenticatedUserProvider.get();
      authenticatedUser.init(credentials);
      return authenticatedUser;
    }
 else {
      logger.warn("String_Node_Str");
      logger.debug("String_Node_Str");
      throw new GuacamoleInvalidCredentialsException("String_Node_Str",CredentialsInfo.USERNAME_PASSWORD);
    }
  }
}

Fixed version (ground truth):
/** 
 * Returns an AuthenticatedUser representing the user authenticated by the given credentials.
 * @param credentials The credentials to use for authentication.
 * @return An AuthenticatedUser representing the user authenticated by the given credentials.
 * @throws GuacamoleException If an error occurs while authenticating the user, or if access is denied.
 */
public AuthenticatedUser authenticateUser(Credentials credentials) throws GuacamoleException {
  HttpServletRequest request=credentials.getRequest();
  RadiusPacket radPack;
  if (credentials.getUsername() == null || credentials.getUsername().isEmpty())   return null;
  if (credentials.getPassword() == null || credentials.getPassword().isEmpty())   return null;
  String challengeResponse=request.getParameter(RadiusChallengeResponseField.PARAMETER_NAME);
  if (challengeResponse == null) {
    try {
      radPack=radiusService.authenticate(credentials.getUsername(),credentials.getPassword());
    }
 catch (    GuacamoleException e) {
      logger.error("String_Node_Str",e.getMessage());
      logger.debug("String_Node_Str",e);
      throw new GuacamoleInvalidCredentialsException("String_Node_Str",CredentialsInfo.USERNAME_PASSWORD);
    }
    if (radPack == null) {
      logger.debug("String_Node_Str");
      throw new GuacamoleInvalidCredentialsException("String_Node_Str",CredentialsInfo.USERNAME_PASSWORD);
    }
 else     if (radPack instanceof AccessReject) {
      logger.debug("String_Node_Str");
      throw new GuacamoleInvalidCredentialsException("String_Node_Str",CredentialsInfo.USERNAME_PASSWORD);
    }
 else     if (radPack instanceof AccessChallenge) {
      RadiusAttribute stateAttr=radPack.findAttribute(Attr_State.TYPE);
      if (stateAttr == null) {
        logger.error("String_Node_Str");
        logger.debug("String_Node_Str");
        throw new GuacamoleInvalidCredentialsException("String_Node_Str",CredentialsInfo.USERNAME_PASSWORD);
      }
      RadiusAttribute replyAttr=radPack.findAttribute(Attr_ReplyMessage.TYPE);
      if (replyAttr == null) {
        logger.error("String_Node_Str");
        logger.debug("String_Node_Str");
        throw new GuacamoleInvalidCredentialsException("String_Node_Str",CredentialsInfo.USERNAME_PASSWORD);
      }
      String replyMsg=replyAttr.toString();
      String radiusState=new String(stateAttr.getValue().getBytes());
      Field radiusResponseField=new RadiusChallengeResponseField(replyMsg);
      Field radiusStateField=new RadiusStateField(radiusState);
      CredentialsInfo expectedCredentials=new CredentialsInfo(Arrays.asList(radiusResponseField,radiusStateField));
      throw new GuacamoleInsufficientCredentialsException("String_Node_Str",expectedCredentials);
    }
 else     if (radPack instanceof AccessAccept) {
      try {
        AuthenticatedUser authenticatedUser=authenticatedUserProvider.get();
        authenticatedUser.init(credentials);
        return authenticatedUser;
      }
  finally {
        radiusService.disconnect();
      }
    }
 else     throw new GuacamoleInvalidCredentialsException("String_Node_Str",CredentialsInfo.USERNAME_PASSWORD);
  }
 else {
    try {
      radPack=radiusService.authenticate(credentials.getUsername(),request.getParameter(RadiusStateField.PARAMETER_NAME),challengeResponse);
    }
 catch (    GuacamoleException e) {
      logger.error("String_Node_Str",e.getMessage());
      logger.debug("String_Node_Str",e);
      radPack=null;
    }
 finally {
      radiusService.disconnect();
    }
    if (radPack instanceof AccessAccept) {
      AuthenticatedUser authenticatedUser=authenticatedUserProvider.get();
      authenticatedUser.init(credentials);
      return authenticatedUser;
    }
 else {
      logger.warn("String_Node_Str");
      logger.debug("String_Node_Str");
      throw new GuacamoleInvalidCredentialsException("String_Node_Str",CredentialsInfo.USERNAME_PASSWORD);
    }
  }
}