/*
* 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.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.handler.codec.http.HttpResponse;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;
import static io.netty.handler.codec.http.HttpHeaders.Names.*;
import static io.netty.handler.codec.http.HttpMethod.*;
import static io.netty.handler.codec.http.HttpResponseStatus.*;
/**
* Handles <a href="http://www.w3.org/TR/cors/">Cross Origin Resource Sharing</a> (CORS) requests.
* <p>
* This handler can be configured using a {@link CorsConfig}, please
* refer to this class for details about the configuration options available.
*/
public class CorsHandler extends ChannelDuplexHandler {
private static final InternalLogger logger = InternalLoggerFactory.getInstance(CorsHandler.class);
private final CorsConfig config;
private HttpRequest request;
public CorsHandler(final CorsConfig config) {
this.config = config;
}
@Override
public void channelRead(final ChannelHandlerContext ctx, final Object msg) throws Exception {
if (config.isCorsSupportEnabled() && msg instanceof HttpRequest) {
request = (HttpRequest) msg;
if (isPreflightRequest(request)) {
handlePreflight(ctx, request);
return;
}
if (config.isShortCurcuit() && !validateOrigin()) {
forbidden(ctx, request);
return;
}
}
ctx.fireChannelRead(msg);
}
private void handlePreflight(final ChannelHandlerContext ctx, final HttpRequest request) {
final HttpResponse response = new DefaultFullHttpResponse(request.getProtocolVersion(), OK);
if (setOrigin(response)) {
setAllowMethods(response);
setAllowHeaders(response);
setAllowCredentials(response);
setMaxAge(response);
setPreflightHeaders(response);
}
ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
}
/**
* This is a non CORS specification feature which enables the setting of preflight
* response headers that might be required by intermediaries.
*
* @param response the HttpResponse to which the preflight response headers should be added.
*/
private void setPreflightHeaders(final HttpResponse response) {
response.headers().add(config.preflightResponseHeaders());
}
private boolean setOrigin(final HttpResponse response) {
final String origin = request.headers().get(ORIGIN);
if (origin != null) {
if ("null".equals(origin) && config.isNullOriginAllowed()) {
setAnyOrigin(response);
return true;
}
if (config.isAnyOriginSupported()) {
if (config.isCredentialsAllowed()) {
echoRequestOrigin(response);
setVaryHeader(response);
} else {
setAnyOrigin(response);
}
return true;
}
if (config.origins().contains(origin)) {
setOrigin(response, origin);
setVaryHeader(response);
return true;
}
logger.debug("Request origin [" + origin + "] was not among the configured origins " + config.origins());
}
return false;
}
private boolean validateOrigin() {
if (config.isAnyOriginSupported()) {
return true;
}
final String origin = request.headers().get(ORIGIN);
if (origin == null) {
// Not a CORS request so we cannot validate it. It may be a non CORS request.
return true;
}
if ("null".equals(origin) && config.isNullOriginAllowed()) {
return true;
}
return config.origins().contains(origin);
}
private void echoRequestOrigin(final HttpResponse response) {
setOrigin(response, request.headers().get(ORIGIN));
}
private static void setVaryHeader(final HttpResponse response) {
response.headers().set(VARY, ORIGIN);
}
private static void setAnyOrigin(final HttpResponse response) {
setOrigin(response, "*");
}
private static void setOrigin(final HttpResponse response, final String origin) {
response.headers().set(ACCESS_CONTROL_ALLOW_ORIGIN, origin);
}
private void setAllowCredentials(final HttpResponse response) {
if (config.isCredentialsAllowed()) {
response.headers().set(ACCESS_CONTROL_ALLOW_CREDENTIALS, "true");
}
}
private static boolean isPreflightRequest(final HttpRequest request) {
final HttpHeaders headers = request.headers();
return request.getMethod().equals(OPTIONS) &&
headers.contains(ORIGIN) &&
headers.contains(ACCESS_CONTROL_REQUEST_METHOD);
}
private void setExposeHeaders(final HttpResponse response) {
if (!config.exposedHeaders().isEmpty()) {
response.headers().set(ACCESS_CONTROL_EXPOSE_HEADERS, config.exposedHeaders());
}
}
private void setAllowMethods(final HttpResponse response) {
response.headers().set(ACCESS_CONTROL_ALLOW_METHODS, config.allowedRequestMethods());
}
private void setAllowHeaders(final HttpResponse response) {
response.headers().set(ACCESS_CONTROL_ALLOW_HEADERS, config.allowedRequestHeaders());
}
private void setMaxAge(final HttpResponse response) {
response.headers().set(ACCESS_CONTROL_MAX_AGE, config.maxAge());
}
@Override
public void write(final ChannelHandlerContext ctx, final Object msg, final ChannelPromise promise)
throws Exception {
if (config.isCorsSupportEnabled() && msg instanceof HttpResponse) {
final HttpResponse response = (HttpResponse) msg;
if (setOrigin(response)) {
setAllowCredentials(response);
setAllowHeaders(response);
setExposeHeaders(response);
}
}
ctx.writeAndFlush(msg, promise);
}
@Override
public void exceptionCaught(final ChannelHandlerContext ctx, final Throwable cause) throws Exception {
logger.error("Caught error in CorsHandler", cause);
ctx.fireExceptionCaught(cause);
}
private static void forbidden(final ChannelHandlerContext ctx, final HttpRequest request) {
ctx.writeAndFlush(new DefaultFullHttpResponse(request.getProtocolVersion(), FORBIDDEN))
.addListener(ChannelFutureListener.CLOSE);
}
}