content: /**
   * Licensed 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.aurora.scheduler.http;
  
  import java.io.IOException;
  
  import javax.servlet.FilterChain;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import javax.ws.rs.HttpMethod;
  
  import com.google.common.annotations.VisibleForTesting;
  import com.google.common.net.HttpHeaders;
  
  import org.apache.aurora.common.base.MorePreconditions;
  
  /*
   * A filter that adds CORS headers to HTTP responses. This filter enables CORS support for a single
   * domain.
   */
  public class CorsFilter extends AbstractFilter {
  
    @VisibleForTesting
    static final String ALLOWED_METHODS = String.join(
        ",",
        HttpMethod.DELETE,
        HttpMethod.GET,
        HttpMethod.HEAD,
        HttpMethod.OPTIONS,
        HttpMethod.POST,
        HttpMethod.PUT);
  
    @VisibleForTesting
    static final String ALLOWED_HEADERS = String.join(
        ",",
        HttpHeaders.ACCEPT,
        HttpHeaders.CONTENT_TYPE,
        HttpHeaders.ORIGIN,
        HttpHeaders.X_REQUESTED_WITH);
  
    private final String allowedOriginDomain;
  
    /*
     * param allowedOriginDomain a domain for which CORS is enabled.
     */
    public CorsFilter(String allowedOriginDomain) {
      this.allowedOriginDomain = MorePreconditions.checkNotBlank(allowedOriginDomain);
    }
  
    @Override
    public void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
        throws IOException, ServletException {
  
      response.setHeader(HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN, allowedOriginDomain);
      response.setHeader(HttpHeaders.ACCESS_CONTROL_ALLOW_METHODS, ALLOWED_METHODS);
      response.setHeader(HttpHeaders.ACCESS_CONTROL_ALLOW_HEADERS, ALLOWED_HEADERS);
  
      chain.doFilter(request, response);
    }
  }
  