content: /*
   * 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.ambari.server.view;
  
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.net.HttpURLConnection;
  
  import org.apache.ambari.server.configuration.ComponentSSLConfiguration;
  import org.apache.ambari.server.controller.internal.URLStreamProvider;
  import org.apache.ambari.server.proxy.ProxyService;
  import org.apache.ambari.view.HttpImpersonator;
  import org.apache.ambari.view.ImpersonatorSetting;
  import org.apache.ambari.view.ViewContext;
  import org.apache.http.client.utils.URIBuilder;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * Class for Ambari to impersonate users over HTTP request.
   * This is handy for Views like Jobs that needs to query ATS via HTTP Get requests and
   * impersonate the currently logged on user.
   * Or a file browser view that needs to use WebHDFS with the credentials of the current user.
   */
  public class HttpImpersonatorImpl implements HttpImpersonator {
    private ViewContext context;
    private final URLStreamProvider urlStreamProvider;
  
    private static final Logger LOG = LoggerFactory.getLogger(HttpImpersonatorImpl.class);
  
    public HttpImpersonatorImpl(ViewContext c) {
      this.context = c;
  
      ComponentSSLConfiguration configuration = ComponentSSLConfiguration.instance();
      this.urlStreamProvider = new URLStreamProvider(ProxyService.URL_CONNECT_TIMEOUT,
          ProxyService.URL_READ_TIMEOUT, configuration.getTruststorePath(),
          configuration.getTruststorePassword(), configuration.getTruststoreType());
    }
  
    public HttpImpersonatorImpl(ViewContext c, URLStreamProvider urlStreamProvider) {
      this.context = c;
      this.urlStreamProvider = urlStreamProvider;
    }
  
    public ViewContext getContext() {
      return this.context;
    }
  
    public String getUsername() {
      return getContext().getUsername();
    }
  
    /**
     * @param conn HTTP connection that will be modified and returned
     * @param type HTTP Request type: GET, PUT, POST, DELETE, etc.
     * @return HTTP Connection object with the "doAs" query param set to the currently logged on user.
     */
    @Override
    public HttpURLConnection doAs(HttpURLConnection conn, String type)  {
      String username = getUsername();
      return doAs(conn, type, username, ImpersonatorSettingImpl.DEFAULT_DO_AS_PARAM);
    }
  
    /**
     * @param conn HTTP connection that will be modified and returned
     * @param type HTTP Request type: GET, PUT, POST, DELETE, etc.
     * @param username Username to impersonate
     * @param doAsParamName Query param, typically "doAs"
     * @return HTTP Connection object with the doAs query param set to the provider username.
     */
    @Override
    public HttpURLConnection doAs(HttpURLConnection conn, String type, String username, String doAsParamName) {
      String url = conn.getURL().toString();
      if (url.toLowerCase().contains(doAsParamName.toLowerCase())) {
        throw new IllegalArgumentException("URL cannot contain \"" + doAsParamName + "\" parameter");
      }
  
      try {
        conn.setRequestMethod(type);
      } catch (IOException e) {
        return null;
      }
  
      conn.setRequestProperty(doAsParamName, username);
      return conn;
    }
  
    /**
     * Returns the result of the HTTP request by setting the "doAs" impersonation for the query param and username
     * in @param impersonatorSetting.
     * @param url URL to request
     * @param requestType HTTP Request type: GET, PUT, POST, DELETE, etc.
     * @param impersonatorSetting Setting class with default values for username and doAs param name.
     *                           To use different values, call the setters of the object.
     * @return Return a response as a String
     */
    @Override
    public String requestURL(String url, String requestType, final ImpersonatorSetting impersonatorSetting) {
      String result = "";
      BufferedReader rd;
      String line;
  
      if (url.toLowerCase().contains(impersonatorSetting.getDoAsParamName().toLowerCase())) {
        throw new IllegalArgumentException("URL cannot contain \"" + impersonatorSetting.getDoAsParamName() + "\" parameter");
      }
  
      try {
        String username = impersonatorSetting.getUsername();
        if (username != null) {
          URIBuilder builder = new URIBuilder(url);
          builder.addParameter(impersonatorSetting.getDoAsParamName(), username);
          url = builder.build().toString();
        }
  
        HttpURLConnection connection = urlStreamProvider.processURL(url, requestType, (String) null, null);
  
        int responseCode = connection.getResponseCode();
        InputStream resultInputStream;
        if (responseCode >= ProxyService.HTTP_ERROR_RANGE_START) {
          resultInputStream = connection.getErrorStream();
        } else {
          resultInputStream = connection.getInputStream();
        }
  
        rd = new BufferedReader(new InputStreamReader(resultInputStream));
  
        line = rd.readLine();
        while (line != null) {
          result += line;
          line = rd.readLine();
        }
        rd.close();
      } catch (Exception e) {
        LOG.error("Exception caught processing impersonator request.", e);
      }
      return result;
    }
  }
  