/*
* Copyright 2002-2018 the original author or authors.
*
* Licensed 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
*
* https://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.springframework.web.filter;
import java.io.IOException;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import java.util.function.Supplier;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
import org.springframework.http.HttpRequest;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.ServletServerHttpRequest;
import org.springframework.lang.Nullable;
import org.springframework.util.CollectionUtils;
import org.springframework.util.LinkedCaseInsensitiveMap;
import org.springframework.util.StringUtils;
import org.springframework.web.util.UriComponents;
import org.springframework.web.util.UriComponentsBuilder;
import org.springframework.web.util.UrlPathHelper;
/**
* Extract values from "Forwarded" and "X-Forwarded-*" headers, wrap the request
* and response, and make they reflect the client-originated protocol and
* address in the following methods:
* <ul>
* <li>{@link HttpServletRequest#getServerName() getServerName()}
* <li>{@link HttpServletRequest#getServerPort() getServerPort()}
* <li>{@link HttpServletRequest#getScheme() getScheme()}
* <li>{@link HttpServletRequest#isSecure() isSecure()}
* <li>{@link HttpServletResponse#sendRedirect(String) sendRedirect(String)}.
* </ul>
*
* <p>This filter can also be used in a {@link #setRemoveOnly removeOnly} mode
* where "Forwarded" and "X-Forwarded-*" headers are eliminated, and not used.
*
* @author Rossen Stoyanchev
* @author Eddú Meléndez
* @author Rob Winch
* @since 4.3
* @see <a href="https://tools.ietf.org/html/rfc7239">https://tools.ietf.org/html/rfc7239</a>
*/
public class ForwardedHeaderFilter extends OncePerRequestFilter {
private static final Set<String> FORWARDED_HEADER_NAMES =
Collections.newSetFromMap(new LinkedCaseInsensitiveMap<>(6, Locale.ENGLISH));
static {
FORWARDED_HEADER_NAMES.add("Forwarded");
FORWARDED_HEADER_NAMES.add("X-Forwarded-Host");
FORWARDED_HEADER_NAMES.add("X-Forwarded-Port");
FORWARDED_HEADER_NAMES.add("X-Forwarded-Proto");
FORWARDED_HEADER_NAMES.add("X-Forwarded-Prefix");
FORWARDED_HEADER_NAMES.add("X-Forwarded-Ssl");
}
private final UrlPathHelper pathHelper;
private boolean removeOnly;
private boolean relativeRedirects;
public ForwardedHeaderFilter() {
this.pathHelper = new UrlPathHelper();
this.pathHelper.setUrlDecode(false);
this.pathHelper.setRemoveSemicolonContent(false);
}
/**
* Enables mode in which any "Forwarded" or "X-Forwarded-*" headers are
* removed only and the information in them ignored.
* @param removeOnly whether to discard and ignore forwarded headers
* @since 4.3.9
*/
public void setRemoveOnly(boolean removeOnly) {
this.removeOnly = removeOnly;
}
/**
* Use this property to enable relative redirects as explained in
* {@link RelativeRedirectFilter}, and also using the same response wrapper
* as that filter does, or if both are configured, only one will wrap.
* <p>By default, if this property is set to false, in which case calls to
* {@link HttpServletResponse#sendRedirect(String)} are overridden in order
* to turn relative into absolute URLs, also taking into account forwarded
* headers.
* @param relativeRedirects whether to use relative redirects
* @since 4.3.10
*/
public void setRelativeRedirects(boolean relativeRedirects) {
this.relativeRedirects = relativeRedirects;
}
@Override
protected boolean shouldNotFilter(HttpServletRequest request) {
for (String headerName : FORWARDED_HEADER_NAMES) {
if (request.getHeader(headerName) != null) {
return false;
}
}
return true;
}
@Override
protected boolean shouldNotFilterAsyncDispatch() {
return false;
}
@Override
protected boolean shouldNotFilterErrorDispatch() {
return false;
}
@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
FilterChain filterChain) throws ServletException, IOException {
if (this.removeOnly) {
ForwardedHeaderRemovingRequest wrappedRequest = new ForwardedHeaderRemovingRequest(request);
filterChain.doFilter(wrappedRequest, response);
}
else {
HttpServletRequest wrappedRequest =
new ForwardedHeaderExtractingRequest(request, this.pathHelper);
HttpServletResponse wrappedResponse = this.relativeRedirects ?
RelativeRedirectResponseWrapper.wrapIfNecessary(response, HttpStatus.SEE_OTHER) :
new ForwardedHeaderExtractingResponse(response, wrappedRequest);
filterChain.doFilter(wrappedRequest, wrappedResponse);
}
}
/**
* Hide "Forwarded" or "X-Forwarded-*" headers.
*/
private static class ForwardedHeaderRemovingRequest extends HttpServletRequestWrapper {
private final Map<String, List<String>> headers;
public ForwardedHeaderRemovingRequest(HttpServletRequest request) {
super(request);
this.headers = initHeaders(request);
}
private static Map<String, List<String>> initHeaders(HttpServletRequest request) {
Map<String, List<String>> headers = new LinkedCaseInsensitiveMap<>(Locale.ENGLISH);
Enumeration<String> names = request.getHeaderNames();
while (names.hasMoreElements()) {
String name = names.nextElement();
if (!FORWARDED_HEADER_NAMES.contains(name)) {
headers.put(name, Collections.list(request.getHeaders(name)));
}
}
return headers;
}
// Override header accessors to not expose forwarded headers
@Override
@Nullable
public String getHeader(String name) {
List<String> value = this.headers.get(name);
return (CollectionUtils.isEmpty(value) ? null : value.get(0));
}
@Override
public Enumeration<String> getHeaders(String name) {
List<String> value = this.headers.get(name);
return (Collections.enumeration(value != null ? value : Collections.emptySet()));
}
@Override
public Enumeration<String> getHeaderNames() {
return Collections.enumeration(this.headers.keySet());
}
}
/**
* Extract and use "Forwarded" or "X-Forwarded-*" headers.
*/
private static class ForwardedHeaderExtractingRequest extends ForwardedHeaderRemovingRequest {
@Nullable
private final String scheme;
private final boolean secure;
@Nullable
private final String host;
private final int port;
private final ForwardedPrefixExtractor forwardedPrefixExtractor;
ForwardedHeaderExtractingRequest(HttpServletRequest request, UrlPathHelper pathHelper) {
super(request);
HttpRequest httpRequest = new ServletServerHttpRequest(request);
UriComponents uriComponents = UriComponentsBuilder.fromHttpRequest(httpRequest).build();
int port = uriComponents.getPort();
this.scheme = uriComponents.getScheme();
this.secure = "https".equals(this.scheme);
this.host = uriComponents.getHost();
this.port = (port == -1 ? (this.secure ? 443 : 80) : port);
String baseUrl = this.scheme + "://" + this.host + (port == -1 ? "" : ":" + port);
Supplier<HttpServletRequest> delegateRequest = () -> (HttpServletRequest) getRequest();
this.forwardedPrefixExtractor = new ForwardedPrefixExtractor(delegateRequest, pathHelper, baseUrl);
}
@Override
@Nullable
public String getScheme() {
return this.scheme;
}
@Override
@Nullable
public String getServerName() {
return this.host;
}
@Override
public int getServerPort() {
return this.port;
}
@Override
public boolean isSecure() {
return this.secure;
}
@Override
public String getContextPath() {
return this.forwardedPrefixExtractor.getContextPath();
}
@Override
public String getRequestURI() {
return this.forwardedPrefixExtractor.getRequestUri();
}
@Override
public StringBuffer getRequestURL() {
return this.forwardedPrefixExtractor.getRequestUrl();
}
}
/**
* Responsible for the contextPath, requestURI, and requestURL with forwarded
* headers in mind, and also taking into account changes to the path of the
* underlying delegate request (e.g. on a Servlet FORWARD).
*/
private static class ForwardedPrefixExtractor {
private final Supplier<HttpServletRequest> delegate;
private final UrlPathHelper pathHelper;
private final String baseUrl;
private String actualRequestUri;
@Nullable
private final String forwardedPrefix;
@Nullable
private String requestUri;
private String requestUrl;
/**
* Constructor with required information.
* @param delegateRequest supplier for the current
* {@link HttpServletRequestWrapper#getRequest() delegate request} which
* may change during a forward (e.g. Tomcat.
* @param pathHelper the path helper instance
* @param baseUrl the host, scheme, and port based on forwarded headers
*/
public ForwardedPrefixExtractor(
Supplier<HttpServletRequest> delegateRequest, UrlPathHelper pathHelper, String baseUrl) {
this.delegate = delegateRequest;
this.pathHelper = pathHelper;
this.baseUrl = baseUrl;
this.actualRequestUri = delegateRequest.get().getRequestURI();
this.forwardedPrefix = initForwardedPrefix(delegateRequest.get());
this.requestUri = initRequestUri();
this.requestUrl = initRequestUrl(); // Keep the order: depends on requestUri
}
@Nullable
private static String initForwardedPrefix(HttpServletRequest request) {
String result = null;
Enumeration<String> names = request.getHeaderNames();
while (names.hasMoreElements()) {
String name = names.nextElement();
if ("X-Forwarded-Prefix".equalsIgnoreCase(name)) {
result = request.getHeader(name);
}
}
if (result != null) {
while (result.endsWith("/")) {
result = result.substring(0, result.length() - 1);
}
}
return result;
}
@Nullable
private String initRequestUri() {
if (this.forwardedPrefix != null) {
return this.forwardedPrefix + this.pathHelper.getPathWithinApplication(this.delegate.get());
}
return null;
}
private String initRequestUrl() {
return this.baseUrl + (this.requestUri != null ? this.requestUri : this.delegate.get().getRequestURI());
}
public String getContextPath() {
return this.forwardedPrefix == null ? this.delegate.get().getContextPath() : this.forwardedPrefix;
}
public String getRequestUri() {
if (this.requestUri == null) {
return this.delegate.get().getRequestURI();
}
recalculatePathsIfNecessary();
return this.requestUri;
}
public StringBuffer getRequestUrl() {
recalculatePathsIfNecessary();
return new StringBuffer(this.requestUrl);
}
private void recalculatePathsIfNecessary() {
if (!this.actualRequestUri.equals(this.delegate.get().getRequestURI())) {
// Underlying path change (e.g. Servlet FORWARD).
this.actualRequestUri = this.delegate.get().getRequestURI();
this.requestUri = initRequestUri();
this.requestUrl = initRequestUrl(); // Keep the order: depends on requestUri
}
}
}
private static class ForwardedHeaderExtractingResponse extends HttpServletResponseWrapper {
private static final String FOLDER_SEPARATOR = "/";
private final HttpServletRequest request;
ForwardedHeaderExtractingResponse(HttpServletResponse response, HttpServletRequest request) {
super(response);
this.request = request;
}
@Override
public void sendRedirect(String location) throws IOException {
UriComponentsBuilder builder = UriComponentsBuilder.fromUriString(location);
UriComponents uriComponents = builder.build();
// Absolute location
if (uriComponents.getScheme() != null) {
super.sendRedirect(location);
return;
}
// Network-path reference
if (location.startsWith("//")) {
String scheme = this.request.getScheme();
super.sendRedirect(builder.scheme(scheme).toUriString());
return;
}
String path = uriComponents.getPath();
if (path != null) {
// Relative to Servlet container root or to current request
path = (path.startsWith(FOLDER_SEPARATOR) ? path :
StringUtils.applyRelativePath(this.request.getRequestURI(), path));
}
String result = UriComponentsBuilder
.fromHttpRequest(new ServletServerHttpRequest(this.request))
.replacePath(path)
.replaceQuery(uriComponents.getQuery())
.fragment(uriComponents.getFragment())
.build().normalize().toUriString();
super.sendRedirect(result);
}
}
}
