* itself if this connection does not use SSL.
   */
  internal var socket: Socket? = null
  private var handshake: Handshake? = null
  private var protocol: Protocol? = null
  private var source: BufferedSource? = null
  private var sink: BufferedSink? = null
  private var connection: RealConnection? = null

  /** True if this connection is ready for use, including TCP, tunnels, and TLS. */

 *
 * <p>For up-to-date Unicode character properties (digit, letter, etc.) and support for
 * supplementary code points, use ICU4J UCharacter and UnicodeSet (freeze() after building). For
 * basic text processing based on UnicodeSet use the ICU4J UnicodeSetSpanner.
 *
 * <p>Example usages:
 *
 * <pre>
 *   String trimmed = {@link #whitespace() whitespace()}.{@link #trimFrom trimFrom}(userInput);

For a quick installation, docker-compose reference configs are also available on the [Casdoor Try with Docker](https://casdoor.org/docs/basic/try-with-docker).

### Configure Casdoor

- Go to Applications
  - Create or use an existing Casdoor application
  - Edit the application
    - Copy `Client ID` and `Client secret`
    - Add your redirect url (callback url) to `Redirect URLs`
    - Save

- Go to Users
  - Edit the user

    /**
    * Sent by the server to indicate that the server and client are
    * on the same machine.  This implies that the server will include
    * a local security context handle in the Type 2 message, for
    * use in local authentication.
    */
    public static final int NTLMSSP_NEGOTIATE_LOCAL_CALL = 0x00004000;

    /**
    * Indicates that authenticated communication between the client

     * required resolving with the authority. SID cache entries are currently not
     * expired because under normal circumstances SID information never changes.
     * 
     * @param tc
     *            context to use
     * @param authorityServerName
     *            The hostname of the server that should be queried. For maximum efficiency this should be the hostname

 * 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,

 * 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,

 * 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,

OAuth2 is a specification that defines several ways to handle authentication and authorization.

It is quite an extensive specification and covers several complex use cases.

It includes ways to authenticate using a "third party".

That's what all the systems with "login with Facebook, Google, Twitter, GitHub" use underneath.

### OAuth 1

# make FESS_HOME absolute
FESS_HOME=`cd "$FESS_HOME"; pwd`


# If an include wasn't specified in the environment, then search for one...
if [ "x$FESS_INCLUDE" = "x" ]; then
    # Locations (in order) to use when searching for an include file.
    for include in /usr/share/fess/fess.in.sh \
                   /usr/local/share/fess/fess.in.sh \
                   /opt/fess/bin/fess.in.sh \
                   ~/.fess.in.sh \