/**
    * 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.hadoop.hbase.rest;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  
  import org.apache.commons.cli.CommandLine;
  import org.apache.commons.cli.HelpFormatter;
  import org.apache.commons.cli.Options;
  import org.apache.commons.cli.ParseException;
  import org.apache.commons.cli.PosixParser;
  import org.apache.commons.lang.ArrayUtils;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.HBaseConfiguration;
  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
  import org.apache.hadoop.hbase.http.HttpServer;
  import org.apache.hadoop.hbase.http.InfoServer;
  import org.apache.hadoop.hbase.jetty.SslSelectChannelConnectorSecure;
  import org.apache.hadoop.hbase.rest.filter.AuthFilter;
  import org.apache.hadoop.hbase.rest.filter.RestCsrfPreventionFilter;
  import org.apache.hadoop.hbase.security.UserProvider;
  import org.apache.hadoop.hbase.util.DNS;
  import org.apache.hadoop.hbase.util.HttpServerUtil;
  import org.apache.hadoop.hbase.util.Pair;
  import org.apache.hadoop.hbase.util.Strings;
  import org.apache.hadoop.hbase.util.VersionInfo;
  import org.apache.hadoop.util.StringUtils;
  import org.mortbay.jetty.Connector;
  import org.mortbay.jetty.Server;
  import org.mortbay.jetty.nio.SelectChannelConnector;
  import org.mortbay.jetty.servlet.Context;
  import org.mortbay.jetty.servlet.FilterHolder;
  import org.mortbay.jetty.servlet.ServletHolder;
  import org.mortbay.thread.QueuedThreadPool;
  
  import com.google.common.base.Preconditions;
  import com.sun.jersey.api.json.JSONConfiguration;
  import com.sun.jersey.spi.container.servlet.ServletContainer;
  
  /**
   * Main class for launching REST gateway as a servlet hosted by Jetty.
   * <p>
   * The following options are supported:
   * <ul>
   * <li>-p --port : service port</li>
   * <li>-ro --readonly : server mode</li>
   * </ul>
   */
  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.TOOLS)
  public class RESTServer implements Constants {
    static Log LOG = LogFactory.getLog("RESTServer");
  
    static String REST_CSRF_ENABLED_KEY = "hbase.rest.csrf.enabled";
    static boolean REST_CSRF_ENABLED_DEFAULT = false;
    static boolean restCSRFEnabled = false;
    static String REST_CSRF_CUSTOM_HEADER_KEY ="hbase.rest.csrf.custom.header";
    static String REST_CSRF_CUSTOM_HEADER_DEFAULT = "X-XSRF-HEADER";
    static String REST_CSRF_METHODS_TO_IGNORE_KEY = "hbase.rest.csrf.methods.to.ignore";
    static String REST_CSRF_METHODS_TO_IGNORE_DEFAULT = "GET,OPTIONS,HEAD,TRACE";
    static String REST_HTTP_ALLOW_OPTIONS_METHOD = "hbase.rest.http.allow.options.method";
    // HTTP OPTIONS method is commonly used in REST APIs for negotiation. It is disabled by default to
    // maintain backward incompatibility
    private static boolean REST_HTTP_ALLOW_OPTIONS_METHOD_DEFAULT = false;
  
    private static void printUsageAndExit(Options options, int exitCode) {
      HelpFormatter formatter = new HelpFormatter();
      formatter.printHelp("bin/hbase rest start", "", options,
        "\nTo run the REST server as a daemon, execute " +
        "bin/hbase-daemon.sh start|stop rest [--infoport <port>] [-p <port>] [-ro]\n", true);
      System.exit(exitCode);
    }
  
    /**
     * Returns a list of strings from a comma-delimited configuration value.
     *
     * @param conf configuration to check
     * @param name configuration property name
    * @param defaultValue default value if no value found for name
    * @return list of strings from comma-delimited configuration value, or an
    *     empty list if not found
    */
   private static List<String> getTrimmedStringList(Configuration conf,
     String name, String defaultValue) {
     String valueString = conf.get(name, defaultValue);
     if (valueString == null) {
       return new ArrayList<>();
     }
     return new ArrayList<>(StringUtils.getTrimmedStringCollection(valueString));
   }
 
   static String REST_CSRF_BROWSER_USERAGENTS_REGEX_KEY = "hbase.rest-csrf.browser-useragents-regex";
   static void addCSRFFilter(Context context, Configuration conf) {
     restCSRFEnabled = conf.getBoolean(REST_CSRF_ENABLED_KEY, REST_CSRF_ENABLED_DEFAULT);
     if (restCSRFEnabled) {
       String[] urls = { "/*" };
       Map<String, String> restCsrfParams = RestCsrfPreventionFilter
           .getFilterParams(conf, "hbase.rest-csrf.");
       HttpServer.defineFilter(context, "csrf", RestCsrfPreventionFilter.class.getName(),
         restCsrfParams, urls);
     }
   }
 
   // login the server principal (if using secure Hadoop)
   private static Pair<FilterHolder, Class<? extends ServletContainer>> loginServerPrincipal(
     UserProvider userProvider, Configuration conf) throws Exception {
     Class<? extends ServletContainer> containerClass = ServletContainer.class;
     if (userProvider.isHadoopSecurityEnabled() && userProvider.isHBaseSecurityEnabled()) {
       String machineName = Strings.domainNamePointerToHostName(
         DNS.getDefaultHost(conf.get(REST_DNS_INTERFACE, "default"),
           conf.get(REST_DNS_NAMESERVER, "default")));
       String keytabFilename = conf.get(REST_KEYTAB_FILE);
       Preconditions.checkArgument(keytabFilename != null && !keytabFilename.isEmpty(),
         REST_KEYTAB_FILE + " should be set if security is enabled");
       String principalConfig = conf.get(REST_KERBEROS_PRINCIPAL);
       Preconditions.checkArgument(principalConfig != null && !principalConfig.isEmpty(),
         REST_KERBEROS_PRINCIPAL + " should be set if security is enabled");
       userProvider.login(REST_KEYTAB_FILE, REST_KERBEROS_PRINCIPAL, machineName);
       if (conf.get(REST_AUTHENTICATION_TYPE) != null) {
         containerClass = RESTServletContainer.class;
         FilterHolder authFilter = new FilterHolder();
         authFilter.setClassName(AuthFilter.class.getName());
         authFilter.setName("AuthenticationFilter");
         return new Pair<FilterHolder, Class<? extends ServletContainer>>(authFilter,containerClass);
       }
     }
     return new Pair<FilterHolder, Class<? extends ServletContainer>>(null, containerClass);
   }
 
   private static void parseCommandLine(String[] args, RESTServlet servlet) {
     Options options = new Options();
     options.addOption("p", "port", true, "Port to bind to [default: " + DEFAULT_LISTEN_PORT + "]");
     options.addOption("ro", "readonly", false, "Respond only to GET HTTP " +
       "method requests [default: false]");
     options.addOption(null, "infoport", true, "Port for web UI");
 
     CommandLine commandLine = null;
     try {
       commandLine = new PosixParser().parse(options, args);
     } catch (ParseException e) {
       LOG.error("Could not parse: ", e);
       printUsageAndExit(options, -1);
     }
 
     // check for user-defined port setting, if so override the conf
     if (commandLine != null && commandLine.hasOption("port")) {
       String val = commandLine.getOptionValue("port");
       servlet.getConfiguration().setInt("hbase.rest.port", Integer.parseInt(val));
       if (LOG.isDebugEnabled()) {
         LOG.debug("port set to " + val);
       }
     }
 
     // check if server should only process GET requests, if so override the conf
     if (commandLine != null && commandLine.hasOption("readonly")) {
       servlet.getConfiguration().setBoolean("hbase.rest.readonly", true);
       if (LOG.isDebugEnabled()) {
         LOG.debug("readonly set to true");
       }
     }
 
     // check for user-defined info server port setting, if so override the conf
     if (commandLine != null && commandLine.hasOption("infoport")) {
       String val = commandLine.getOptionValue("infoport");
       servlet.getConfiguration().setInt("hbase.rest.info.port", Integer.parseInt(val));
       if (LOG.isDebugEnabled()) {
         LOG.debug("Web UI port set to " + val);
       }
     }
 
     @SuppressWarnings("unchecked")
     List<String> remainingArgs = commandLine != null ?
         commandLine.getArgList() : new ArrayList<String>();
     if (remainingArgs.size() != 1) {
       printUsageAndExit(options, 1);
     }
 
     String command = remainingArgs.get(0);
     if ("start".equals(command)) {
       // continue and start container
     } else if ("stop".equals(command)) {
       System.exit(1);
     } else {
       printUsageAndExit(options, 1);
     }
   }
 
   /**
    * The main method for the HBase rest server.
    * @param args command-line arguments
    * @throws Exception exception
    */
   public static void main(String[] args) throws Exception {
     VersionInfo.logVersion();
     Configuration conf = HBaseConfiguration.create();
     UserProvider userProvider = UserProvider.instantiate(conf);
     Pair<FilterHolder, Class<? extends ServletContainer>> pair = loginServerPrincipal(
       userProvider, conf);
     FilterHolder authFilter = pair.getFirst();
     Class<? extends ServletContainer> containerClass = pair.getSecond();
     RESTServlet servlet = RESTServlet.getInstance(conf, userProvider);
 
     parseCommandLine(args, servlet);
 
     // set up the Jersey servlet container for Jetty
     ServletHolder sh = new ServletHolder(containerClass);
     sh.setInitParameter(
       "com.sun.jersey.config.property.resourceConfigClass",
       ResourceConfig.class.getCanonicalName());
     sh.setInitParameter("com.sun.jersey.config.property.packages",
       "jetty");
     // The servlet holder below is instantiated to only handle the case
     // of the /status/cluster returning arrays of nodes (live/dead). Without
     // this servlet holder, the problem is that the node arrays in the response
     // are collapsed to single nodes. We want to be able to treat the
     // node lists as POJO in the response to /status/cluster servlet call,
     // but not change the behavior for any of the other servlets
     // Hence we don't use the servlet holder for all servlets / paths
     ServletHolder shPojoMap = new ServletHolder(containerClass);
     @SuppressWarnings("unchecked")
     Map<String, String> shInitMap = sh.getInitParameters();
     for (Entry<String, String> e : shInitMap.entrySet()) {
       shPojoMap.setInitParameter(e.getKey(), e.getValue());
     }
     shPojoMap.setInitParameter(JSONConfiguration.FEATURE_POJO_MAPPING, "true");
 
     // set up Jetty and run the embedded server
 
     Server server = new Server();
 
     Connector connector = new SelectChannelConnector();
     if(conf.getBoolean(REST_SSL_ENABLED, false)) {
       SslSelectChannelConnectorSecure sslConnector = new SslSelectChannelConnectorSecure();
       String keystore = conf.get(REST_SSL_KEYSTORE_STORE);
       String password = HBaseConfiguration.getPassword(conf,
         REST_SSL_KEYSTORE_PASSWORD, null);
       String keyPassword = HBaseConfiguration.getPassword(conf,
         REST_SSL_KEYSTORE_KEYPASSWORD, password);
       sslConnector.setKeystore(keystore);
       sslConnector.setPassword(password);
       sslConnector.setKeyPassword(keyPassword);
       connector = sslConnector;
     }
     connector.setPort(servlet.getConfiguration().getInt("hbase.rest.port", DEFAULT_LISTEN_PORT));
     connector.setHost(servlet.getConfiguration().get("hbase.rest.host", "0.0.0.0"));
     connector.setHeaderBufferSize(65536);
 
     server.addConnector(connector);
 
     // Set the default max thread number to 100 to limit
     // the number of concurrent requests so that REST server doesn't OOM easily.
     // Jetty set the default max thread number to 250, if we don't set it.
     //
     // Our default min thread number 2 is the same as that used by Jetty.
     int maxThreads = servlet.getConfiguration().getInt("hbase.rest.threads.max", 100);
     int minThreads = servlet.getConfiguration().getInt("hbase.rest.threads.min", 2);
     QueuedThreadPool threadPool = new QueuedThreadPool(maxThreads);
     threadPool.setMinThreads(minThreads);
     server.setThreadPool(threadPool);
 
     server.setSendServerVersion(false);
     server.setSendDateHeader(false);
     server.setStopAtShutdown(true);
       // set up context
     Context context = new Context(server, "/", Context.SESSIONS);
     context.addServlet(shPojoMap, "/status/cluster");
     context.addServlet(sh, "/*");
     if (authFilter != null) {
       context.addFilter(authFilter, "/*", 1);
     }
 
     // Load filters from configuration.
     String[] filterClasses = servlet.getConfiguration().getStrings(FILTER_CLASSES,
       ArrayUtils.EMPTY_STRING_ARRAY);
     for (String filter : filterClasses) {
       filter = filter.trim();
       context.addFilter(Class.forName(filter), "/*", 0);
     }
     addCSRFFilter(context, conf);
     HttpServerUtil.constrainHttpMethods(context, servlet.getConfiguration()
         .getBoolean(REST_HTTP_ALLOW_OPTIONS_METHOD, REST_HTTP_ALLOW_OPTIONS_METHOD_DEFAULT));
 
     // Put up info server.
     int port = conf.getInt("hbase.rest.info.port", 8085);
     if (port >= 0) {
       conf.setLong("startcode", System.currentTimeMillis());
       String a = conf.get("hbase.rest.info.bindAddress", "0.0.0.0");
       InfoServer infoServer = new InfoServer("rest", a, port, false, conf);
       infoServer.setAttribute("hbase.conf", conf);
       infoServer.start();
     }
     // start server
     server.start();
     server.join();
   }
 }