/*
* Copyright 2002-2017 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
*
* 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.springframework.web.cors;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import org.springframework.http.HttpMethod;
import org.springframework.util.CollectionUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
/**
* A container for CORS configuration along with methods to check against the
* actual origin, HTTP methods, and headers of a given request.
*
* <p>By default a newly created {@code CorsConfiguration} does not permit any
* cross-origin requests and must be configured explicitly to indicate what
* should be allowed.
*
* <p>Use {@link #applyPermitDefaultValues()} to flip the initialization model
* to start with open defaults that permit all cross-origin requests for GET,
* HEAD, and POST requests.
*
* @author Sebastien Deleuze
* @author Rossen Stoyanchev
* @author Juergen Hoeller
* @author Sam Brannen
* @since 4.2
* @see <a href="http://www.w3.org/TR/cors/">CORS W3C recommendation</a>
*/
public class CorsConfiguration {
/**
* Wildcard representing <em>all</em> origins, methods, or headers.
*/
public static final String ALL = "*";
private static final List<HttpMethod> DEFAULT_METHODS;
static {
List<HttpMethod> rawMethods = new ArrayList<>(2);
rawMethods.add(HttpMethod.GET);
rawMethods.add(HttpMethod.HEAD);
DEFAULT_METHODS = Collections.unmodifiableList(rawMethods);
}
private List<String> allowedOrigins;
private List<String> allowedMethods;
private List<HttpMethod> resolvedMethods = DEFAULT_METHODS;
private List<String> allowedHeaders;
private List<String> exposedHeaders;
private Boolean allowCredentials;
private Long maxAge;
/**
* Construct a new {@code CorsConfiguration} instance with no cross-origin
* requests allowed for any origin by default.
* @see #applyPermitDefaultValues()
*/
public CorsConfiguration() {
}
/**
* Construct a new {@code CorsConfiguration} instance by copying all
* values from the supplied {@code CorsConfiguration}.
*/
public CorsConfiguration(CorsConfiguration other) {
this.allowedOrigins = other.allowedOrigins;
this.allowedMethods = other.allowedMethods;
this.resolvedMethods = other.resolvedMethods;
this.allowedHeaders = other.allowedHeaders;
this.exposedHeaders = other.exposedHeaders;
this.allowCredentials = other.allowCredentials;
this.maxAge = other.maxAge;
}
/**
* Set the origins to allow, e.g. {@code "http://domain1.com"}.
* <p>The special value {@code "*"} allows all domains.
* <p>By default this is not set.
*/
public void setAllowedOrigins(List<String> allowedOrigins) {
this.allowedOrigins = (allowedOrigins != null ? new ArrayList<>(allowedOrigins) : null);
}
/**
* Return the configured origins to allow, or {@code null} if none.
* @see #addAllowedOrigin(String)
* @see #setAllowedOrigins(List)
*/
public List<String> getAllowedOrigins() {
return this.allowedOrigins;
}
/**
* Add an origin to allow.
*/
public void addAllowedOrigin(String origin) {
if (this.allowedOrigins == null) {
this.allowedOrigins = new ArrayList<>(4);
}
this.allowedOrigins.add(origin);
}
/**
* Set the HTTP methods to allow, e.g. {@code "GET"}, {@code "POST"},
* {@code "PUT"}, etc.
* <p>The special value {@code "*"} allows all methods.
* <p>If not set, only {@code "GET"} and {@code "HEAD"} are allowed.
* <p>By default this is not set.
*/
public void setAllowedMethods(List<String> allowedMethods) {
this.allowedMethods = (allowedMethods != null ? new ArrayList<>(allowedMethods) : null);
if (!CollectionUtils.isEmpty(allowedMethods)) {
this.resolvedMethods = new ArrayList<>(allowedMethods.size());
for (String method : allowedMethods) {
if (ALL.equals(method)) {
this.resolvedMethods = null;
break;
}
this.resolvedMethods.add(HttpMethod.resolve(method));
}
}
else {
this.resolvedMethods = DEFAULT_METHODS;
}
}
/**
* Return the allowed HTTP methods, or {@code null} in which case
* only {@code "GET"} and {@code "HEAD"} allowed.
* @see #addAllowedMethod(HttpMethod)
* @see #addAllowedMethod(String)
* @see #setAllowedMethods(List)
*/
public List<String> getAllowedMethods() {
return this.allowedMethods;
}
/**
* Add an HTTP method to allow.
*/
public void addAllowedMethod(HttpMethod method) {
if (method != null) {
addAllowedMethod(method.name());
}
}
/**
* Add an HTTP method to allow.
*/
public void addAllowedMethod(String method) {
if (StringUtils.hasText(method)) {
if (this.allowedMethods == null) {
this.allowedMethods = new ArrayList<>(4);
this.resolvedMethods = new ArrayList<>(4);
}
this.allowedMethods.add(method);
if (ALL.equals(method)) {
this.resolvedMethods = null;
}
else if (this.resolvedMethods != null) {
this.resolvedMethods.add(HttpMethod.resolve(method));
}
}
}
/**
* Set the list of headers that a pre-flight request can list as allowed
* for use during an actual request.
* <p>The special value {@code "*"} allows actual requests to send any
* header.
* <p>A header name is not required to be listed if it is one of:
* {@code Cache-Control}, {@code Content-Language}, {@code Expires},
* {@code Last-Modified}, or {@code Pragma}.
* <p>By default this is not set.
*/
public void setAllowedHeaders(List<String> allowedHeaders) {
this.allowedHeaders = (allowedHeaders != null ? new ArrayList<>(allowedHeaders) : null);
}
/**
* Return the allowed actual request headers, or {@code null} if none.
* @see #addAllowedHeader(String)
* @see #setAllowedHeaders(List)
*/
public List<String> getAllowedHeaders() {
return this.allowedHeaders;
}
/**
* Add an actual request header to allow.
*/
public void addAllowedHeader(String allowedHeader) {
if (this.allowedHeaders == null) {
this.allowedHeaders = new ArrayList<>(4);
}
this.allowedHeaders.add(allowedHeader);
}
/**
* Set the list of response headers other than simple headers (i.e.
* {@code Cache-Control}, {@code Content-Language}, {@code Content-Type},
* {@code Expires}, {@code Last-Modified}, or {@code Pragma}) that an
* actual response might have and can be exposed.
* <p>Note that {@code "*"} is not a valid exposed header value.
* <p>By default this is not set.
*/
public void setExposedHeaders(List<String> exposedHeaders) {
if (exposedHeaders != null && exposedHeaders.contains(ALL)) {
throw new IllegalArgumentException("'*' is not a valid exposed header value");
}
this.exposedHeaders = (exposedHeaders != null ? new ArrayList<>(exposedHeaders) : null);
}
/**
* Return the configured response headers to expose, or {@code null} if none.
* @see #addExposedHeader(String)
* @see #setExposedHeaders(List)
*/
public List<String> getExposedHeaders() {
return this.exposedHeaders;
}
/**
* Add a response header to expose.
* <p>Note that {@code "*"} is not a valid exposed header value.
*/
public void addExposedHeader(String exposedHeader) {
if (ALL.equals(exposedHeader)) {
throw new IllegalArgumentException("'*' is not a valid exposed header value");
}
if (this.exposedHeaders == null) {
this.exposedHeaders = new ArrayList<>(4);
}
this.exposedHeaders.add(exposedHeader);
}
/**
* Whether user credentials are supported.
* <p>By default this is not set (i.e. user credentials are not supported).
*/
public void setAllowCredentials(Boolean allowCredentials) {
this.allowCredentials = allowCredentials;
}
/**
* Return the configured {@code allowCredentials} flag, or {@code null} if none.
* @see #setAllowCredentials(Boolean)
*/
public Boolean getAllowCredentials() {
return this.allowCredentials;
}
/**
* Configure how long, in seconds, the response from a pre-flight request
* can be cached by clients.
* <p>By default this is not set.
*/
public void setMaxAge(Long maxAge) {
this.maxAge = maxAge;
}
/**
* Return the configured {@code maxAge} value, or {@code null} if none.
* @see #setMaxAge(Long)
*/
public Long getMaxAge() {
return this.maxAge;
}
/**
* By default a newly created {@code CorsConfiguration} does not permit any
* cross-origin requests and must be configured explicitly to indicate what
* should be allowed.
*
* <p>Use this method to flip the initialization model to start with open
* defaults that permit all cross-origin requests for GET, HEAD, and POST
* requests. Note however that this method will not override any existing
* values already set.
*
* <p>The following defaults are applied if not already set:
* <ul>
* <li>Allow all origins, i.e. {@code "*"}.</li>
* <li>Allow "simple" methods {@code GET}, {@code HEAD} and {@code POST}.</li>
* <li>Allow all headers.</li>
* <li>Allow credentials.</li>
* <li>Set max age to 1800 seconds (30 minutes).</li>
* </ul>
*/
public CorsConfiguration applyPermitDefaultValues() {
if (this.allowedOrigins == null) {
this.addAllowedOrigin(ALL);
}
if (this.allowedMethods == null) {
this.setAllowedMethods(Arrays.asList(
HttpMethod.GET.name(), HttpMethod.HEAD.name(), HttpMethod.POST.name()));
}
if (this.allowedHeaders == null) {
this.addAllowedHeader(ALL);
}
if (this.allowCredentials == null) {
this.setAllowCredentials(true);
}
if (this.maxAge == null) {
this.setMaxAge(1800L);
}
return this;
}
/**
* Combine the supplied {@code CorsConfiguration} with this one.
* <p>Properties of this configuration are overridden by any non-null
* properties of the supplied one.
* @return the combined {@code CorsConfiguration} or {@code this}
* configuration if the supplied configuration is {@code null}
*/
public CorsConfiguration combine(CorsConfiguration other) {
if (other == null) {
return this;
}
CorsConfiguration config = new CorsConfiguration(this);
config.setAllowedOrigins(combine(getAllowedOrigins(), other.getAllowedOrigins()));
config.setAllowedMethods(combine(getAllowedMethods(), other.getAllowedMethods()));
config.setAllowedHeaders(combine(getAllowedHeaders(), other.getAllowedHeaders()));
config.setExposedHeaders(combine(getExposedHeaders(), other.getExposedHeaders()));
Boolean allowCredentials = other.getAllowCredentials();
if (allowCredentials != null) {
config.setAllowCredentials(allowCredentials);
}
Long maxAge = other.getMaxAge();
if (maxAge != null) {
config.setMaxAge(maxAge);
}
return config;
}
private List<String> combine(List<String> source, List<String> other) {
if (other == null || other.contains(ALL)) {
return source;
}
if (source == null || source.contains(ALL)) {
return other;
}
Set<String> combined = new LinkedHashSet<>(source);
combined.addAll(other);
return new ArrayList<>(combined);
}
/**
* Check the origin of the request against the configured allowed origins.
* @param requestOrigin the origin to check
* @return the origin to use for the response, or {@code null} which
* means the request origin is not allowed
*/
public String checkOrigin(String requestOrigin) {
if (!StringUtils.hasText(requestOrigin)) {
return null;
}
if (ObjectUtils.isEmpty(this.allowedOrigins)) {
return null;
}
if (this.allowedOrigins.contains(ALL)) {
if (this.allowCredentials != Boolean.TRUE) {
return ALL;
}
else {
return requestOrigin;
}
}
for (String allowedOrigin : this.allowedOrigins) {
if (requestOrigin.equalsIgnoreCase(allowedOrigin)) {
return requestOrigin;
}
}
return null;
}
/**
* Check the HTTP request method (or the method from the
* {@code Access-Control-Request-Method} header on a pre-flight request)
* against the configured allowed methods.
* @param requestMethod the HTTP request method to check
* @return the list of HTTP methods to list in the response of a pre-flight
* request, or {@code null} if the supplied {@code requestMethod} is not allowed
*/
public List<HttpMethod> checkHttpMethod(HttpMethod requestMethod) {
if (requestMethod == null) {
return null;
}
if (this.resolvedMethods == null) {
return Collections.singletonList(requestMethod);
}
return (this.resolvedMethods.contains(requestMethod) ? this.resolvedMethods : null);
}
/**
* Check the supplied request headers (or the headers listed in the
* {@code Access-Control-Request-Headers} of a pre-flight request) against
* the configured allowed headers.
* @param requestHeaders the request headers to check
* @return the list of allowed headers to list in the response of a pre-flight
* request, or {@code null} if none of the supplied request headers is allowed
*/
public List<String> checkHeaders(List<String> requestHeaders) {
if (requestHeaders == null) {
return null;
}
if (requestHeaders.isEmpty()) {
return Collections.emptyList();
}
if (ObjectUtils.isEmpty(this.allowedHeaders)) {
return null;
}
boolean allowAnyHeader = this.allowedHeaders.contains(ALL);
List<String> result = new ArrayList<>(requestHeaders.size());
for (String requestHeader : requestHeaders) {
if (StringUtils.hasText(requestHeader)) {
requestHeader = requestHeader.trim();
if (allowAnyHeader) {
result.add(requestHeader);
}
else {
for (String allowedHeader : this.allowedHeaders) {
if (requestHeader.equalsIgnoreCase(allowedHeader)) {
result.add(requestHeader);
break;
}
}
}
}
}
return (result.isEmpty() ? null : result);
}
}