/*
 * 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.http;

import java.io.IOException;
import java.net.URI;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.CommonConfigurationKeys;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.security.authorize.AccessControlList;
import org.apache.yetus.audience.InterfaceAudience;

import org.apache.hbase.thirdparty.com.google.common.net.HostAndPort;
import org.apache.hbase.thirdparty.org.eclipse.jetty.ee8.servlet.ServletHolder;

/**
 * Create a Jetty embedded server to answer http requests. The primary goal is to serve up status
 * information for the server. There are three contexts: "/stacks/" -> points to stack trace
 * "/static/" -> points to common static files (src/hbase-webapps/static) "/" -> the jsp
 * server code from (src/hbase-webapps/<name>)
 */
@InterfaceAudience.Private
public class InfoServer {
  private static final String HBASE_APP_DIR = "hbase-webapps";
  private final org.apache.hadoop.hbase.http.HttpServer httpServer;

  private static final String HADOOP_WEB_TLS_CONFIG_PREFIX = "ssl.server.";
  private static final String HBASE_WEB_TLS_CONFIG_PREFIX = "hbase.ui.ssl.";

  /**
   * Create a status server on the given port. The jsp scripts are taken from
   * src/hbase-webapps/<code>name</code>.
   * @param name        The name of the server
   * @param bindAddress address to bind to
   * @param port        The port to use on the server
   * @param findPort    whether the server should start at the given port and increment by 1 until
   *                    it finds a free port.
   * @param c           the {@link Configuration} to build the server
   * @throws IOException if getting one of the password fails or the server cannot be created
   */
  public InfoServer(String name, String bindAddress, int port, boolean findPort,
    final Configuration c) throws IOException {
    HttpConfig httpConfig = new HttpConfig(c);
    HttpServer.Builder builder = new org.apache.hadoop.hbase.http.HttpServer.Builder();

    builder.setName(name)
      .addEndpoint(URI
        .create(httpConfig.getSchemePrefix() + HostAndPort.fromParts(bindAddress, port).toString()))
      .setAppDir(HBASE_APP_DIR).setFindPort(findPort).setConf(c);
    String logDir = System.getProperty("hbase.log.dir");
    if (logDir != null) {
      builder.setLogDir(logDir);
    }
    if (httpConfig.isSecure()) {
      // We are using the Hadoop HTTP server config properties.
      // This makes it easy to keep in sync with Hadoop's UI servers, but hard to set this
      // separately for HBase.
      builder.keyPassword(getTLSPassword(c, "keystore.keypassword"))
        .keyStore(getTLSProperty(c, "keystore.location"), getTLSPassword(c, "keystore.password"),
          getTLSProperty(c, "keystore.type", "jks"))
        .trustStore(getTLSProperty(c, "truststore.location"),
          getTLSPassword(c, "truststore.password"), getTLSProperty(c, "truststore.type", "jks"))
        // The ssl.server.*.protocols properties do not exist in Hadoop at the time of writing.
        .setIncludeProtocols(getTLSProperty(c, "include.protocols"))
        .setExcludeProtocols(getTLSProperty(c, "exclude.protocols"))
        .setIncludeCiphers(getTLSProperty(c, "include.cipher.list"))
        .setExcludeCiphers(getTLSProperty(c, "exclude.cipher.list"));
    }

    final String httpAuthType = c.get(HttpServer.HTTP_UI_AUTHENTICATION, "").toLowerCase();
    // Enable SPNEGO authentication
    if ("kerberos".equals(httpAuthType)) {
      builder.setUsernameConfKey(HttpServer.HTTP_SPNEGO_AUTHENTICATION_PRINCIPAL_KEY)
        .setKeytabConfKey(HttpServer.HTTP_SPNEGO_AUTHENTICATION_KEYTAB_KEY)
        .setKerberosNameRulesKey(HttpServer.HTTP_SPNEGO_AUTHENTICATION_KRB_NAME_KEY)
        .setSignatureSecretFileKey(HttpServer.HTTP_AUTHENTICATION_SIGNATURE_SECRET_FILE_KEY)
        .setSecurityEnabled(true);
    }

    // Set an admin ACL on sensitive webUI endpoints (works only if SPNEGO or LDAP is enabled)
    if ("ldap".equals(httpAuthType) || "kerberos".equals(httpAuthType)) {
      AccessControlList acl = buildAdminAcl(c);
      builder.setACL(acl);
    }

    this.httpServer = builder.build();
  }

  private String getTLSPassword(Configuration c, String postfix) throws IOException {
    return HBaseConfiguration.getPassword(c, HBASE_WEB_TLS_CONFIG_PREFIX + postfix,
      HBaseConfiguration.getPassword(c, HADOOP_WEB_TLS_CONFIG_PREFIX + postfix, null));
  }

  private String getTLSProperty(Configuration c, String postfix) {
    return getTLSProperty(c, postfix, null);
  }

  private String getTLSProperty(Configuration c, String postfix, String defaultValue) {
    return c.get(HBASE_WEB_TLS_CONFIG_PREFIX + postfix,
      c.get(HADOOP_WEB_TLS_CONFIG_PREFIX + postfix, defaultValue));
  }

  /**
   * Builds an ACL that will restrict the users who can issue commands to endpoints on the UI which
   * are meant only for administrators.
   */
  static AccessControlList buildAdminAcl(Configuration conf) {
    // Initialize admin users based on whether http ui auth is set to ldap or kerberos
    String httpAuthType = conf.get(HttpServer.HTTP_UI_AUTHENTICATION, "").toLowerCase();
    final String adminUsers = getAdminUsers(conf, httpAuthType);
    final String adminGroups =
      conf.get(HttpServer.HTTP_SPNEGO_AUTHENTICATION_ADMIN_GROUPS_KEY, null);
    if (adminUsers == null && adminGroups == null) {
      // Backwards compatibility - if the user doesn't have anything set, allow all users in.
      return new AccessControlList("*", null);
    }
    return new AccessControlList(adminUsers, adminGroups);
  }

  private static String getAdminUsers(Configuration conf, String httpAuthType) {
    if ("kerberos".equals(httpAuthType)) {
      return conf.get(HttpServer.HTTP_SPNEGO_AUTHENTICATION_ADMIN_USERS_KEY, null);
    } else if ("ldap".equals(httpAuthType)) {
      return conf.get(HttpServer.HTTP_LDAP_AUTHENTICATION_ADMIN_USERS_KEY, null);
    }
    // If the auth type is not kerberos or ldap, return null
    return null;
  }

  /**
   * Explicitly invoke {@link #addPrivilegedServlet(String, String, Class)} or
   * {@link #addUnprivilegedServlet(String, String, Class)} instead of this method. This method will
   * add a servlet which any authenticated user can access.
   * @deprecated Use {@link #addUnprivilegedServlet(String, String, Class)} or
   *             {@link #addPrivilegedServlet(String, String, Class)} instead of this method which
   *             does not state outwardly what kind of authz rules will be applied to this servlet.
   */
  @Deprecated
  public void addServlet(String name, String pathSpec, Class<? extends HttpServlet> clazz) {
    addUnprivilegedServlet(name, pathSpec, clazz);
  }

  /**
   * Adds a servlet in the server that any user can access.
   * @see HttpServer#addUnprivilegedServlet(String, String, Class)
   */
  public void addUnprivilegedServlet(String name, String pathSpec,
    Class<? extends HttpServlet> clazz) {
    this.httpServer.addUnprivilegedServlet(name, pathSpec, clazz);
  }

  /**
   * Adds a servlet in the server that any user can access.
   * @see HttpServer#addUnprivilegedServlet(String, ServletHolder)
   */
  public void addUnprivilegedServlet(String name, String pathSpec, ServletHolder holder) {
    if (name != null) {
      holder.setName(name);
    }
    this.httpServer.addUnprivilegedServlet(pathSpec, holder);
  }

  /**
   * Adds a servlet in the server that any user can access.
   * @see HttpServer#addPrivilegedServlet(String, String, Class)
   */
  public void addPrivilegedServlet(String name, String pathSpec,
    Class<? extends HttpServlet> clazz) {
    this.httpServer.addPrivilegedServlet(name, pathSpec, clazz);
  }

  public void setAttribute(String name, Object value) {
    this.httpServer.setAttribute(name, value);
  }

  public void start() throws IOException {
    this.httpServer.start();
  }

  /**
   * @return the port of the info server
   * @deprecated Since 0.99.0
   */
  @Deprecated
  public int getPort() {
    return this.httpServer.getPort();
  }

  public void stop() throws Exception {
    this.httpServer.stop();
  }

  /**
   * Returns true if and only if UI authentication (spnego) is enabled, UI authorization is enabled,
   * and the requesting user is defined as an administrator. If the UI is set to readonly, this
   * method always returns false.
   */
  public static boolean canUserModifyUI(HttpServletRequest req, ServletContext ctx,
    Configuration conf) {
    if (conf.getBoolean("hbase.master.ui.readonly", false)) {
      return false;
    }
    String remoteUser = req.getRemoteUser();
    if (
      "kerberos".equalsIgnoreCase(conf.get(HttpServer.HTTP_UI_AUTHENTICATION))
        && conf.getBoolean(CommonConfigurationKeys.HADOOP_SECURITY_AUTHORIZATION, false)
        && remoteUser != null
    ) {
      return HttpServer.userHasAdministratorAccess(ctx, remoteUser);
    }
    return false;
  }
}