/*
 * 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.
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package org.apache.kafka.common.config.internals;

import org.apache.kafka.common.config.SaslConfigs;

import java.util.Collections;
import java.util.List;

/**
 * Common home for broker-side security configs which need to be accessible from the libraries shared
 * between the broker and the client.
 *
 * Note this is an internal API and subject to change without notice.
 */
public class BrokerSecurityConfigs {

    public static final String PRINCIPAL_BUILDER_CLASS_CONFIG = "principal.builder.class";
    public static final String SASL_KERBEROS_PRINCIPAL_TO_LOCAL_RULES_CONFIG = "sasl.kerberos.principal.to.local.rules";
    public static final String SSL_CLIENT_AUTH_CONFIG = "ssl.client.auth";
    public static final String SASL_ENABLED_MECHANISMS_CONFIG = "sasl.enabled.mechanisms";
    public static final String SASL_SERVER_CALLBACK_HANDLER_CLASS = "sasl.server.callback.handler.class";

    public static final String PRINCIPAL_BUILDER_CLASS_DOC = "The fully qualified name of a class that implements the " +
            "KafkaPrincipalBuilder interface, which is used to build the KafkaPrincipal object used during " +
            "authorization. This config also supports the deprecated PrincipalBuilder interface which was previously " +
            "used for client authentication over SSL. If no principal builder is defined, the default behavior depends " +
            "on the security protocol in use. For SSL authentication, the principal name will be the distinguished " +
            "name from the client certificate if one is provided; otherwise, if client authentication is not required, " +
            "the principal name will be ANONYMOUS. For SASL authentication, the principal will be derived using the " +
            "rules defined by <code>" + SASL_KERBEROS_PRINCIPAL_TO_LOCAL_RULES_CONFIG + "</code> if GSSAPI is in use, " +
            "and the SASL authentication ID for other mechanisms. For PLAINTEXT, the principal will be ANONYMOUS.";

    public static final String SASL_KERBEROS_PRINCIPAL_TO_LOCAL_RULES_DOC = "A list of rules for mapping from principal " +
            "names to short names (typically operating system usernames). The rules are evaluated in order and the " +
            "first rule that matches a principal name is used to map it to a short name. Any later rules in the list are " +
            "ignored. By default, principal names of the form {username}/{hostname}@{REALM} are mapped to {username}. " +
            "For more details on the format please see <a href=\"#security_authz\"> security authorization and acls</a>. " +
            "Note that this configuration is ignored if an extension of KafkaPrincipalBuilder is provided by the " +
            "<code>" + PRINCIPAL_BUILDER_CLASS_CONFIG + "</code> configuration.";
    public static final List<String> DEFAULT_SASL_KERBEROS_PRINCIPAL_TO_LOCAL_RULES = Collections.singletonList("DEFAULT");

    public static final String SSL_CLIENT_AUTH_DOC = "Configures kafka broker to request client authentication."
            + " The following settings are common: "
            + " <ul>"
            + " <li><code>ssl.client.auth=required</code> If set to required"
            + " client authentication is required."
            + " <li><code>ssl.client.auth=requested</code> This means client authentication is optional."
            + " unlike requested , if this option is set client can choose not to provide authentication information about itself"
            + " <li><code>ssl.client.auth=none</code> This means client authentication is not needed.";

    public static final String SASL_ENABLED_MECHANISMS_DOC = "The list of SASL mechanisms enabled in the Kafka server. "
            + "The list may contain any mechanism for which a security provider is available. "
            + "Only GSSAPI is enabled by default.";
    public static final List<String> DEFAULT_SASL_ENABLED_MECHANISMS = Collections.singletonList(SaslConfigs.GSSAPI_MECHANISM);

    public static final String SASL_SERVER_CALLBACK_HANDLER_CLASS_DOC = "The fully qualified name of a SASL server callback handler "
            + "class that implements the AuthenticateCallbackHandler interface. Server callback handlers must be prefixed with "
            + "listener prefix and SASL mechanism name in lower-case. For example, "
            + "listener.name.sasl_ssl.plain.sasl.server.callback.handler.class=com.example.CustomPlainCallbackHandler.";

}
