/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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 org.elasticsearch.http.netty4.cors;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpMethod;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.handler.codec.http.HttpResponse;
import io.netty.handler.codec.http.HttpResponseStatus;
import org.elasticsearch.common.Strings;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
/**
* 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 Netty4CorsConfig}, please
* refer to this class for details about the configuration options available.
*
* This code was borrowed from Netty 4 and refactored to work for Elasticsearch's Netty 3 setup.
*/
public class Netty4CorsHandler extends ChannelDuplexHandler {
public static final String ANY_ORIGIN = "*";
private static Pattern SCHEME_PATTERN = Pattern.compile("^https?://");
private final Netty4CorsConfig config;
private HttpRequest request;
/**
* Creates a new instance with the specified {@link Netty4CorsConfig}.
*/
public Netty4CorsHandler(final Netty4CorsConfig config) {
if (config == null) {
throw new NullPointerException();
}
this.config = config;
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
if (config.isCorsSupportEnabled() && msg instanceof HttpRequest) {
request = (HttpRequest) msg;
if (isPreflightRequest(request)) {
handlePreflight(ctx, request);
return;
}
if (config.isShortCircuit() && !validateOrigin()) {
forbidden(ctx, request);
return;
}
}
ctx.fireChannelRead(msg);
}
public static void setCorsResponseHeaders(HttpRequest request, HttpResponse resp, Netty4CorsConfig config) {
if (!config.isCorsSupportEnabled()) {
return;
}
String originHeader = request.headers().get(HttpHeaderNames.ORIGIN);
if (!Strings.isNullOrEmpty(originHeader)) {
final String originHeaderVal;
if (config.isAnyOriginSupported()) {
originHeaderVal = ANY_ORIGIN;
} else if (config.isOriginAllowed(originHeader) || isSameOrigin(originHeader, request.headers().get(HttpHeaderNames.HOST))) {
originHeaderVal = originHeader;
} else {
originHeaderVal = null;
}
if (originHeaderVal != null) {
resp.headers().add(HttpHeaderNames.ACCESS_CONTROL_ALLOW_ORIGIN, originHeaderVal);
}
}
if (config.isCredentialsAllowed()) {
resp.headers().add(HttpHeaderNames.ACCESS_CONTROL_ALLOW_CREDENTIALS, "true");
}
}
private void handlePreflight(final ChannelHandlerContext ctx, final HttpRequest request) {
final HttpResponse response = new DefaultFullHttpResponse(request.protocolVersion(), HttpResponseStatus.OK, true, true);
if (setOrigin(response)) {
setAllowMethods(response);
setAllowHeaders(response);
setAllowCredentials(response);
setMaxAge(response);
setPreflightHeaders(response);
ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
} else {
forbidden(ctx, request);
}
}
private static void forbidden(final ChannelHandlerContext ctx, final HttpRequest request) {
ctx.writeAndFlush(new DefaultFullHttpResponse(request.protocolVersion(), HttpResponseStatus.FORBIDDEN))
.addListener(ChannelFutureListener.CLOSE);
}
private static boolean isSameOrigin(final String origin, final String host) {
if (Strings.isNullOrEmpty(host) == false) {
// strip protocol from origin
final String originDomain = SCHEME_PATTERN.matcher(origin).replaceFirst("");
if (host.equals(originDomain)) {
return true;
}
}
return false;
}
/**
* 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(HttpHeaderNames.ORIGIN);
if (!Strings.isNullOrEmpty(origin)) {
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.isOriginAllowed(origin)) {
setOrigin(response, origin);
setVaryHeader(response);
return true;
}
}
return false;
}
private boolean validateOrigin() {
if (config.isAnyOriginSupported()) {
return true;
}
final String origin = request.headers().get(HttpHeaderNames.ORIGIN);
if (Strings.isNullOrEmpty(origin)) {
// 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;
}
// if the origin is the same as the host of the request, then allow
if (isSameOrigin(origin, request.headers().get(HttpHeaderNames.HOST))) {
return true;
}
return config.isOriginAllowed(origin);
}
private void echoRequestOrigin(final HttpResponse response) {
setOrigin(response, request.headers().get(HttpHeaderNames.ORIGIN));
}
private static void setVaryHeader(final HttpResponse response) {
response.headers().set(HttpHeaderNames.VARY, HttpHeaderNames.ORIGIN);
}
private static void setAnyOrigin(final HttpResponse response) {
setOrigin(response, ANY_ORIGIN);
}
private static void setOrigin(final HttpResponse response, final String origin) {
response.headers().set(HttpHeaderNames.ACCESS_CONTROL_ALLOW_ORIGIN, origin);
}
private void setAllowCredentials(final HttpResponse response) {
if (config.isCredentialsAllowed()
&& !response.headers().get(HttpHeaderNames.ACCESS_CONTROL_ALLOW_ORIGIN).equals(ANY_ORIGIN)) {
response.headers().set(HttpHeaderNames.ACCESS_CONTROL_ALLOW_CREDENTIALS, "true");
}
}
private static boolean isPreflightRequest(final HttpRequest request) {
final HttpHeaders headers = request.headers();
return request.method().equals(HttpMethod.OPTIONS) &&
headers.contains(HttpHeaderNames.ORIGIN) &&
headers.contains(HttpHeaderNames.ACCESS_CONTROL_REQUEST_METHOD);
}
private void setAllowMethods(final HttpResponse response) {
response.headers().set(HttpHeaderNames.ACCESS_CONTROL_ALLOW_METHODS, config.allowedRequestMethods().stream()
.map(m -> m.name().trim())
.collect(Collectors.toList()));
}
private void setAllowHeaders(final HttpResponse response) {
response.headers().set(HttpHeaderNames.ACCESS_CONTROL_ALLOW_HEADERS, config.allowedRequestHeaders());
}
private void setMaxAge(final HttpResponse response) {
response.headers().set(HttpHeaderNames.ACCESS_CONTROL_MAX_AGE, config.maxAge());
}
}