content: /*
   This file is part of Airsonic.
  
   Airsonic is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
  
   Airsonic is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
  
   You should have received a copy of the GNU General Public License
   along with Airsonic.  If not, see <http://www.gnu.org/licenses/>.
  
   Copyright 2016 (C) Airsonic Authors
   Based upon Subsonic, Copyright 2009 (C) Sindre Mehus
   */
  package org.airsonic.player.filter;
  
  import org.airsonic.player.controller.JAXBWriter;
  import org.airsonic.player.controller.SubsonicRESTController;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.web.bind.ServletRequestBindingException;
  import org.springframework.web.util.NestedServletException;
  
  import javax.servlet.*;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  /**
   * Intercepts exceptions thrown by RESTController.
   *
   * Also adds the CORS response header (http://enable-cors.org)
   *
   * @author Sindre Mehus
   * @version $Revision: 1.1 $ $Date: 2006/03/01 16:58:08 $
   */
  public class RESTFilter implements Filter {
  
      private static final Logger LOG = LoggerFactory.getLogger(RESTFilter.class);
  
      private final JAXBWriter jaxbWriter = new JAXBWriter();
  
      public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) {
          try {
              HttpServletResponse response = (HttpServletResponse) res;
              response.setHeader("Access-Control-Allow-Origin", "*");
              chain.doFilter(req, res);
          } catch (Throwable x) {
              handleException(x, (HttpServletRequest) req, (HttpServletResponse) res);
          }
      }
  
      private void handleException(Throwable x, HttpServletRequest request, HttpServletResponse response) {
          if (x instanceof NestedServletException && x.getCause() != null) {
              x = x.getCause();
          }
  
          SubsonicRESTController.ErrorCode code = (x instanceof ServletRequestBindingException) ? SubsonicRESTController.ErrorCode.MISSING_PARAMETER : SubsonicRESTController.ErrorCode.GENERIC;
          String msg = getErrorMessage(x);
          LOG.warn("Error in REST API: " + msg, x);
  
          try {
              jaxbWriter.writeErrorResponse(request, response, code, msg);
          } catch (Exception e) {
              LOG.error("Failed to write error response.", e);
          }
      }
  
      private String getErrorMessage(Throwable x) {
          if (x.getMessage() != null) {
              return x.getMessage();
          }
          return x.getClass().getSimpleName();
      }
  
      public void init(FilterConfig filterConfig) {
      }
  
      public void destroy() {
      }
  }
  