001package ca.uhn.fhir.rest.server;
002
003/*
004 * #%L
005 * HAPI FHIR - Core Library
006 * %%
007 * Copyright (C) 2014 - 2016 University Health Network
008 * %%
009 * Licensed under the Apache License, Version 2.0 (the "License");
010 * you may not use this file except in compliance with the License.
011 * You may obtain a copy of the License at
012 * 
013 *      http://www.apache.org/licenses/LICENSE-2.0
014 * 
015 * Unless required by applicable law or agreed to in writing, software
016 * distributed under the License is distributed on an "AS IS" BASIS,
017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
018 * See the License for the specific language governing permissions and
019 * limitations under the License.
020 * #L%
021 */
022
023import javax.servlet.ServletContext;
024import javax.servlet.http.HttpServletRequest;
025
026/**
027 * Works like the normal {@link ca.uhn.fhir.rest.server.IncomingRequestAddressStrategy} unless there's an x-forwarded-host present, in which case that's used in place of the server's address.
028 *
029 * If the Apache Http Server <i>mod_proxy</i> isn't configured to supply <i>x-forwarded-proto</i>, the factory method that you use to create the address strategy will determine the default. Note that
030 * <i>mod_proxy</i> doesn't set this by default, but it can be configured via <i>RequestHeader set X-Forwarded-Proto http</i> (or https)
031 *
032 * If you want to set the protocol based on something other than the constructor argument, you should be able to do so by overriding <i>protocol</i>.
033 *
034 * Note that while this strategy was designed to work with Apache Http Server, and has been tested against it, it should work with any proxy server that sets <i>x-forwarded-host</i>
035 *
036 * Created by Bill de Beaubien on 3/30/2015.
037 */
038public class ApacheProxyAddressStrategy extends IncomingRequestAddressStrategy {
039        private boolean myUseHttps = false;
040
041        protected ApacheProxyAddressStrategy(boolean theUseHttps) {
042                myUseHttps = theUseHttps;
043        }
044
045        public static ApacheProxyAddressStrategy forHttp() {
046                return new ApacheProxyAddressStrategy(false);
047        }
048
049        public static ApacheProxyAddressStrategy forHttps() {
050                return new ApacheProxyAddressStrategy(true);
051        }
052
053        @Override
054        public String determineServerBase(ServletContext theServletContext, HttpServletRequest theRequest) {
055                String forwardedHost = getForwardedHost(theRequest);
056                if (forwardedHost != null) {
057                        return forwardedServerBase(theServletContext, theRequest, forwardedHost);
058                }
059                return super.determineServerBase(theServletContext, theRequest);
060        }
061
062        private String getForwardedHost(HttpServletRequest theRequest) {
063                String forwardedHost = theRequest.getHeader("x-forwarded-host");
064                if (forwardedHost != null) {
065                        int commaPos = forwardedHost.indexOf(',');
066                        if (commaPos >= 0) {
067                                forwardedHost = forwardedHost.substring(0, commaPos - 1);
068                        }
069                }
070                return forwardedHost;
071        }
072
073        public String forwardedServerBase(ServletContext theServletContext, HttpServletRequest theRequest, String theForwardedHost) {
074                String serverBase = super.determineServerBase(theServletContext, theRequest);
075                String host = theRequest.getHeader("host");
076                if (host != null) {
077                        serverBase = serverBase.replace(host, theForwardedHost);
078                        serverBase = serverBase.substring(serverBase.indexOf("://"));
079                        return protocol(theRequest) + serverBase;
080                }
081                return serverBase;
082        }
083
084        protected String protocol(HttpServletRequest theRequest) {
085                String protocol = theRequest.getHeader("x-forwarded-proto");
086                if (protocol != null) {
087                        return protocol;
088                }
089                return myUseHttps ? "https" : "http";
090        }
091}