/*
* Copyright 2013 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 io.netty.handler.codec.http.cors;
import io.netty.handler.codec.http.DefaultHttpHeaders;
import io.netty.handler.codec.http.EmptyHttpHeaders;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpMethod;
import io.netty.util.internal.StringUtil;
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.Map.Entry;
import java.util.Set;
import java.util.concurrent.Callable;
/**
* Configuration for Cross-Origin Resource Sharing (CORS).
*/
public final class CorsConfig {
private final Set<String> origins;
private final boolean anyOrigin;
private final boolean enabled;
private final Set<String> exposeHeaders;
private final boolean allowCredentials;
private final long maxAge;
private final Set<HttpMethod> allowedRequestMethods;
private final Set<String> allowedRequestHeaders;
private final boolean allowNullOrigin;
private final Map<CharSequence, Callable<?>> preflightHeaders;
private final boolean shortCurcuit;
private CorsConfig(final Builder builder) {
origins = new LinkedHashSet<String>(builder.origins);
anyOrigin = builder.anyOrigin;
enabled = builder.enabled;
exposeHeaders = builder.exposeHeaders;
allowCredentials = builder.allowCredentials;
maxAge = builder.maxAge;
allowedRequestMethods = builder.requestMethods;
allowedRequestHeaders = builder.requestHeaders;
allowNullOrigin = builder.allowNullOrigin;
preflightHeaders = builder.preflightHeaders;
shortCurcuit = builder.shortCurcuit;
}
/**
* Determines if support for CORS is enabled.
*
* @return {@code true} if support for CORS is enabled, false otherwise.
*/
public boolean isCorsSupportEnabled() {
return enabled;
}
/**
* Determines whether a wildcard origin, '*', is supported.
*
* @return {@code boolean} true if any origin is allowed.
*/
public boolean isAnyOriginSupported() {
return anyOrigin;
}
/**
* Returns the allowed origin. This can either be a wildcard or an origin value.
*
* @return the value that will be used for the CORS response header 'Access-Control-Allow-Origin'
*/
public String origin() {
return origins.isEmpty() ? "*" : origins.iterator().next();
}
/**
* Returns the set of allowed origins.
*
* @return {@code Set} the allowed origins.
*/
public Set<String> origins() {
return origins;
}
/**
* Web browsers may set the 'Origin' request header to 'null' if a resource is loaded
* from the local file system.
*
* If isNullOriginAllowed is true then the server will response with the wildcard for the
* the CORS response header 'Access-Control-Allow-Origin'.
*
* @return {@code true} if a 'null' origin should be supported.
*/
public boolean isNullOriginAllowed() {
return allowNullOrigin;
}
/**
* Returns a set of 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:
* <pre>
* xhr.getResponseHeader("Content-Type");
* </pre>
* The headers that are available by default are:
* <ul>
* <li>Cache-Control</li>
* <li>Content-Language</li>
* <li>Content-Type</li>
* <li>Expires</li>
* <li>Last-Modified</li>
* <li>Pragma</li>
* </ul>
* To expose other headers they need to be specified, which is what this method enables by
* adding the headers names to the CORS 'Access-Control-Expose-Headers' response header.
*
* @return {@code List<String>} a list of the headers to expose.
*/
public Set<String> exposedHeaders() {
return Collections.unmodifiableSet(exposeHeaders);
}
/**
* Determines if cookies are supported for CORS requests.
*
* By default cookies are not included in CORS requests but if isCredentialsAllowed returns
* true cookies will be added to CORS requests. Setting this value to true 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:
* <pre>
* xhr.withCredentials = true;
* </pre>
* The default value for 'withCredentials' is false in which case no cookies are sent.
* Settning this to true will included cookies in cross origin requests.
*
* @return {@code true} if cookies are supported.
*/
public boolean isCredentialsAllowed() {
return allowCredentials;
}
/**
* Gets the maxAge setting.
*
* 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.
*
* @return {@code long} the time in seconds that a preflight request may be cached.
*/
public long maxAge() {
return maxAge;
}
/**
* Returns the allowed set of Request Methods. The Http methods that should be returned in the
* CORS 'Access-Control-Request-Method' response header.
*
* @return {@code Set} of {@link HttpMethod}s that represent the allowed Request Methods.
*/
public Set<HttpMethod> allowedRequestMethods() {
return Collections.unmodifiableSet(allowedRequestMethods);
}
/**
* Returns the allowed set of Request Headers.
*
* The header names returned from this method will be used to set the CORS
* 'Access-Control-Allow-Headers' response header.
*
* @return {@code Set<String>} of strings that represent the allowed Request Headers.
*/
public Set<String> allowedRequestHeaders() {
return Collections.unmodifiableSet(allowedRequestHeaders);
}
/**
* Returns HTTP response headers that should be added to a CORS preflight response.
*
* @return {@link HttpHeaders} the HTTP response headers to be added.
*/
public HttpHeaders preflightResponseHeaders() {
if (preflightHeaders.isEmpty()) {
return EmptyHttpHeaders.INSTANCE;
}
final HttpHeaders preflightHeaders = new DefaultHttpHeaders();
for (Entry<CharSequence, Callable<?>> entry : this.preflightHeaders.entrySet()) {
final Object value = getValue(entry.getValue());
if (value instanceof Iterable) {
preflightHeaders.addObject(entry.getKey(), (Iterable<?>) value);
} else {
preflightHeaders.addObject(entry.getKey(), value);
}
}
return preflightHeaders;
}
/**
* Determines whether 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 {@code true} if a CORS request should short-curcuit upon receiving an invalid Origin header.
*/
public boolean isShortCurcuit() {
return shortCurcuit;
}
private static <T> T getValue(final Callable<T> callable) {
try {
return callable.call();
} catch (final Exception e) {
throw new IllegalStateException("Could not generate value for callable [" + callable + ']', e);
}
}
@Override
public String toString() {
return StringUtil.simpleClassName(this) + "[enabled=" + enabled +
", origins=" + origins +
", anyOrigin=" + anyOrigin +
", exposedHeaders=" + exposeHeaders +
", isCredentialsAllowed=" + allowCredentials +
", maxAge=" + maxAge +
", allowedRequestMethods=" + allowedRequestMethods +
", allowedRequestHeaders=" + allowedRequestHeaders +
", preflightHeaders=" + preflightHeaders + ']';
}
/**
* Creates a Builder instance with it's origin set to '*'.
*
* @return Builder to support method chaining.
*/
public static Builder withAnyOrigin() {
return new Builder();
}
/**
* Creates a {@link Builder} instance with the specified origin.
*
* @return {@link Builder} to support method chaining.
*/
public static Builder withOrigin(final String origin) {
if ("*".equals(origin)) {
return new Builder();
}
return new Builder(origin);
}
/**
* Creates a {@link Builder} instance with the specified origins.
*
* @return {@link Builder} to support method chaining.
*/
public static Builder withOrigins(final String... origins) {
return new Builder(origins);
}
/**
* Builder used to configure and build a CorsConfig instance.
*/
public static class Builder {
private final Set<String> origins;
private final boolean anyOrigin;
private boolean allowNullOrigin;
private boolean enabled = true;
private boolean allowCredentials;
private final Set<String> exposeHeaders = new HashSet<String>();
private long maxAge;
private final Set<HttpMethod> requestMethods = new HashSet<HttpMethod>();
private final Set<String> requestHeaders = new HashSet<String>();
private final Map<CharSequence, Callable<?>> preflightHeaders = new HashMap<CharSequence, Callable<?>>();
private boolean noPreflightHeaders;
private boolean shortCurcuit;
/**
* Creates a new Builder instance with the origin passed in.
*
* @param origins the origin to be used for this builder.
*/
public Builder(final String... origins) {
this.origins = new LinkedHashSet<String>(Arrays.asList(origins));
anyOrigin = false;
}
/**
* Creates a new Builder instance allowing any origin, "*" which is the
* wildcard origin.
*
*/
public Builder() {
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 wildcard for the the CORS response header 'Access-Control-Allow-Origin'.
*
* @return {@link Builder} to support method chaining.
*/
public Builder allowNullOrigin() {
allowNullOrigin = true;
return this;
}
/**
* Disables CORS support.
*
* @return {@link Builder} to support method chaining.
*/
public Builder 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:
* <pre>
* xhr.getResponseHeader("Content-Type");
* </pre>
*
* The headers that are available by default are:
* <ul>
* <li>Cache-Control</li>
* <li>Content-Language</li>
* <li>Content-Type</li>
* <li>Expires</li>
* <li>Last-Modified</li>
* <li>Pragma</li>
* </ul>
*
* 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 Builder} to support method chaining.
*/
public Builder exposeHeaders(final String... headers) {
exposeHeaders.addAll(Arrays.asList(headers));
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:
* <pre>
* xhr.withCredentials = true;
* </pre>
* The default value for 'withCredentials' is false in which case no cookies are sent.
* Settning this to true will included cookies in cross origin requests.
*
* @return {@link Builder} to support method chaining.
*/
public Builder 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 Builder} to support method chaining.
*/
public Builder 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 Builder} to support method chaining.
*/
public Builder 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:
* <pre>
* xhr.setRequestHeader('My-Custom-Header', "SomeValue");
* </pre>
* the server will recieve 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 Builder} to support method chaining.
*/
public Builder allowedRequestHeaders(final String... headers) {
requestHeaders.addAll(Arrays.asList(headers));
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 Builder} to support method chaining.
*/
public Builder 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 <T> the type of values that the Iterable contains.
* @return {@link Builder} to support method chaining.
*/
public <T> Builder preflightResponseHeader(final CharSequence name, final Iterable<T> 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 occomplished 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 <T> the type of the value that the Callable can return.
* @return {@link Builder} to support method chaining.
*/
public <T> Builder preflightResponseHeader(final String name, final Callable<T> valueGenerator) {
preflightHeaders.put(name, valueGenerator);
return this;
}
/**
* Specifies that no preflight response headers should be added to a preflight response.
*
* @return {@link Builder} to support method chaining.
*/
public Builder noPreflightResponseHeaders() {
noPreflightHeaders = 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, new DateValueGenerator());
preflightHeaders.put(HttpHeaderNames.CONTENT_LENGTH, new ConstantValueGenerator("0"));
}
return new CorsConfig(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 Builder} to support method chaining.
*/
public Builder shortCurcuit() {
shortCurcuit = true;
return 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<Object> {
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.
*/
public static final class DateValueGenerator implements Callable<Date> {
@Override
public Date call() throws Exception {
return new Date();
}
}
}