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/*
 * Copyright 2015 The Netty Project
 *
 * The Netty Project 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 nl.topicus.jdbc.shaded.io.netty.handler.codec.http.cors;

import nl.topicus.jdbc.shaded.io.netty.handler.codec.http.HttpHeaderNames;
import nl.topicus.jdbc.shaded.io.netty.handler.codec.http.HttpMethod;

import java.util.Arrays;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.Callable;

/**
 * Builder used to configure and build a {@link CorsConfig} instance.
 */
public final class CorsConfigBuilder {

    /**
     * Creates a Builder instance with it's origin set to '*'.
     *
     * @return Builder to support method chaining.
     */
    public static CorsConfigBuilder forAnyOrigin() {
        return new CorsConfigBuilder();
    }

    /**
     * Creates a {@link CorsConfigBuilder} instance with the specified origin.
     *
     * @return {@link CorsConfigBuilder} to support method chaining.
     */
    public static CorsConfigBuilder forOrigin(final String origin) {
        if ("*".equals(origin)) {
            return new CorsConfigBuilder();
        }
        return new CorsConfigBuilder(origin);
    }

    /**
     * Creates a {@link CorsConfigBuilder} instance with the specified origins.
     *
     * @return {@link CorsConfigBuilder} to support method chaining.
     */
    public static CorsConfigBuilder forOrigins(final String... origins) {
        return new CorsConfigBuilder(origins);
    }

    final Set origins;
    final boolean anyOrigin;
    boolean allowNullOrigin;
    boolean enabled = true;
    boolean allowCredentials;
    final Set exposeHeaders = new HashSet();
    long maxAge;
    final Set requestMethods = new HashSet();
    final Set requestHeaders = new HashSet();
    final Map> preflightHeaders = new HashMap>();
    private boolean noPreflightHeaders;
    boolean shortCircuit;

    /**
     * Creates a new Builder instance with the origin passed in.
     *
     * @param origins the origin to be used for this builder.
     */
    CorsConfigBuilder(final String... origins) {
        this.origins = new LinkedHashSet(Arrays.asList(origins));
        anyOrigin = false;
    }

    /**
     * Creates a new Builder instance allowing any origin, "*" which is the
     * wildcard origin.
     *
     */
    CorsConfigBuilder() {
        anyOrigin = true;
        origins = Collections.emptySet();
    }

    /**
     * Web browsers may set the 'Origin' request header to 'null' if a resource is loaded
     * from the local file system. Calling this method will enable a successful CORS response
     * with a {@code "null"} value for the the CORS response header 'Access-Control-Allow-Origin'.
     *
     * @return {@link CorsConfigBuilder} to support method chaining.
     */
    public CorsConfigBuilder allowNullOrigin() {
        allowNullOrigin = true;
        return this;
    }

    /**
     * Disables CORS support.
     *
     * @return {@link CorsConfigBuilder} to support method chaining.
     */
    public CorsConfigBuilder disable() {
        enabled = false;
        return this;
    }

    /**
     * Specifies the headers to be exposed to calling clients.
     *
     * During a simple CORS request, only certain response headers are made available by the
     * browser, for example using:
     * 
     * xhr.getResponseHeader("Content-Type");
     * 
* * The headers that are available by default are: *
    *
  • Cache-Control
  • *
  • Content-Language
  • *
  • Content-Type
  • *
  • Expires
  • *
  • Last-Modified
  • *
  • Pragma
  • *
* * To expose other headers they need to be specified which is what this method enables by * adding the headers to the CORS 'Access-Control-Expose-Headers' response header. * * @param headers the values to be added to the 'Access-Control-Expose-Headers' response header * @return {@link CorsConfigBuilder} to support method chaining. */ public CorsConfigBuilder exposeHeaders(final String... headers) { exposeHeaders.addAll(Arrays.asList(headers)); return this; } /** * Specifies the headers to be exposed to calling clients. * * During a simple CORS request, only certain response headers are made available by the * browser, for example using: *
     * xhr.getResponseHeader(HttpHeaderNames.CONTENT_TYPE);
     * 
* * The headers that are available by default are: *
    *
  • Cache-Control
  • *
  • Content-Language
  • *
  • Content-Type
  • *
  • Expires
  • *
  • Last-Modified
  • *
  • Pragma
  • *
* * To expose other headers they need to be specified which is what this method enables by * adding the headers to the CORS 'Access-Control-Expose-Headers' response header. * * @param headers the values to be added to the 'Access-Control-Expose-Headers' response header * @return {@link CorsConfigBuilder} to support method chaining. */ public CorsConfigBuilder exposeHeaders(final CharSequence... headers) { for (CharSequence header: headers) { exposeHeaders.add(header.toString()); } return this; } /** * By default cookies are not included in CORS requests, but this method will enable cookies to * be added to CORS requests. Calling this method will set the CORS 'Access-Control-Allow-Credentials' * response header to true. * * Please note, that cookie support needs to be enabled on the client side as well. * The client needs to opt-in to send cookies by calling: *
     * xhr.withCredentials = true;
     * 
* The default value for 'withCredentials' is false in which case no cookies are sent. * Setting this to true will included cookies in cross origin requests. * * @return {@link CorsConfigBuilder} to support method chaining. */ public CorsConfigBuilder allowCredentials() { allowCredentials = true; return this; } /** * When making a preflight request the client has to perform two request with can be inefficient. * This setting will set the CORS 'Access-Control-Max-Age' response header and enables the * caching of the preflight response for the specified time. During this time no preflight * request will be made. * * @param max the maximum time, in seconds, that the preflight response may be cached. * @return {@link CorsConfigBuilder} to support method chaining. */ public CorsConfigBuilder maxAge(final long max) { maxAge = max; return this; } /** * Specifies the allowed set of HTTP Request Methods that should be returned in the * CORS 'Access-Control-Request-Method' response header. * * @param methods the {@link HttpMethod}s that should be allowed. * @return {@link CorsConfigBuilder} to support method chaining. */ public CorsConfigBuilder allowedRequestMethods(final HttpMethod... methods) { requestMethods.addAll(Arrays.asList(methods)); return this; } /** * Specifies the if headers that should be returned in the CORS 'Access-Control-Allow-Headers' * response header. * * If a client specifies headers on the request, for example by calling: *
     * xhr.setRequestHeader('My-Custom-Header', "SomeValue");
     * 
* the server will receive the above header name in the 'Access-Control-Request-Headers' of the * preflight request. The server will then decide if it allows this header to be sent for the * real request (remember that a preflight is not the real request but a request asking the server * if it allow a request). * * @param headers the headers to be added to the preflight 'Access-Control-Allow-Headers' response header. * @return {@link CorsConfigBuilder} to support method chaining. */ public CorsConfigBuilder allowedRequestHeaders(final String... headers) { requestHeaders.addAll(Arrays.asList(headers)); return this; } /** * Specifies the if headers that should be returned in the CORS 'Access-Control-Allow-Headers' * response header. * * If a client specifies headers on the request, for example by calling: *
     * xhr.setRequestHeader('My-Custom-Header', "SomeValue");
     * 
* the server will receive the above header name in the 'Access-Control-Request-Headers' of the * preflight request. The server will then decide if it allows this header to be sent for the * real request (remember that a preflight is not the real request but a request asking the server * if it allow a request). * * @param headers the headers to be added to the preflight 'Access-Control-Allow-Headers' response header. * @return {@link CorsConfigBuilder} to support method chaining. */ public CorsConfigBuilder allowedRequestHeaders(final CharSequence... headers) { for (CharSequence header: headers) { requestHeaders.add(header.toString()); } return this; } /** * Returns HTTP response headers that should be added to a CORS preflight response. * * An intermediary like a load balancer might require that a CORS preflight request * have certain headers set. This enables such headers to be added. * * @param name the name of the HTTP header. * @param values the values for the HTTP header. * @return {@link CorsConfigBuilder} to support method chaining. */ public CorsConfigBuilder preflightResponseHeader(final CharSequence name, final Object... values) { if (values.length == 1) { preflightHeaders.put(name, new ConstantValueGenerator(values[0])); } else { preflightResponseHeader(name, Arrays.asList(values)); } return this; } /** * Returns HTTP response headers that should be added to a CORS preflight response. * * An intermediary like a load balancer might require that a CORS preflight request * have certain headers set. This enables such headers to be added. * * @param name the name of the HTTP header. * @param value the values for the HTTP header. * @param the type of values that the Iterable contains. * @return {@link CorsConfigBuilder} to support method chaining. */ public CorsConfigBuilder preflightResponseHeader(final CharSequence name, final Iterable value) { preflightHeaders.put(name, new ConstantValueGenerator(value)); return this; } /** * Returns HTTP response headers that should be added to a CORS preflight response. * * An intermediary like a load balancer might require that a CORS preflight request * have certain headers set. This enables such headers to be added. * * Some values must be dynamically created when the HTTP response is created, for * example the 'Date' response header. This can be accomplished by using a Callable * which will have its 'call' method invoked when the HTTP response is created. * * @param name the name of the HTTP header. * @param valueGenerator a Callable which will be invoked at HTTP response creation. * @param the type of the value that the Callable can return. * @return {@link CorsConfigBuilder} to support method chaining. */ public CorsConfigBuilder preflightResponseHeader(final CharSequence name, final Callable valueGenerator) { preflightHeaders.put(name, valueGenerator); return this; } /** * Specifies that no preflight response headers should be added to a preflight response. * * @return {@link CorsConfigBuilder} to support method chaining. */ public CorsConfigBuilder noPreflightResponseHeaders() { noPreflightHeaders = true; return this; } /** * Specifies that a CORS request should be rejected if it's invalid before being * further processing. * * CORS headers are set after a request is processed. This may not always be desired * and this setting will check that the Origin is valid and if it is not valid no * further processing will take place, and a error will be returned to the calling client. * * @return {@link CorsConfigBuilder} to support method chaining. */ public CorsConfigBuilder shortCircuit() { shortCircuit = true; return this; } /** * Builds a {@link CorsConfig} with settings specified by previous method calls. * * @return {@link CorsConfig} the configured CorsConfig instance. */ public CorsConfig build() { if (preflightHeaders.isEmpty() && !noPreflightHeaders) { preflightHeaders.put(HttpHeaderNames.DATE, DateValueGenerator.INSTANCE); preflightHeaders.put(HttpHeaderNames.CONTENT_LENGTH, new ConstantValueGenerator("0")); } return new CorsConfig(this); } /** * This class is used for preflight HTTP response values that do not need to be * generated, but instead the value is "static" in that the same value will be returned * for each call. */ private static final class ConstantValueGenerator implements Callable { private final Object value; /** * Sole constructor. * * @param value the value that will be returned when the call method is invoked. */ private ConstantValueGenerator(final Object value) { if (value == null) { throw new IllegalArgumentException("value must not be null"); } this.value = value; } @Override public Object call() { return value; } } /** * This callable is used for the DATE preflight HTTP response HTTP header. * It's value must be generated when the response is generated, hence will be * different for every call. */ private static final class DateValueGenerator implements Callable { static final DateValueGenerator INSTANCE = new DateValueGenerator(); @Override public Date call() throws Exception { return new Date(); } } }