Adding support for specifying preflight response headers.

Motivation:

An intermediary like a load balancer might require that a Cross Origin
Resource Sharing (CORS) preflight request have certain headers set.
As a concrete example the Elastic Load Balancer (ELB) requires the
'Date' and 'Content-Length' header to be set or it will fail with a 502
error code.

This works is an enhancement of https://github.com/netty/netty/pull/2290

Modifications:

CorsConfig has been extended to make additional HTTP response headers
configurable for preflight responses. Since some headers, like the
'Date' header need to be generated each time, m0wfo suggested using a
Callable.

Result:

By default, the 'Date' and 'Content-Lenght' headers will be sent in a
preflight response. This can be overriden and users can specify
any headers that might be required by different intermediaries.
This commit is contained in:
Daniel Bevenius 2014-03-08 16:30:54 +01:00
parent 50f685fa49
commit 8d8bbec274
4 changed files with 388 additions and 35 deletions

View File

@ -15,13 +15,21 @@
*/
package io.netty.handler.codec.http.cors;
import io.netty.handler.codec.http.DefaultHttpHeaders;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpHeaders.Names;
import io.netty.handler.codec.http.HttpMethod;
import io.netty.util.internal.StringUtil;
import java.util.Arrays;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.concurrent.Callable;
/**
* Configuration for Cross-Origin Resource Sharing (CORS).
@ -36,6 +44,7 @@ public final class CorsConfig {
private final Set<HttpMethod> allowedRequestMethods;
private final Set<String> allowedRequestHeaders;
private final boolean allowNullOrigin;
private final Map<CharSequence, Callable<?>> preflightHeaders;
private CorsConfig(final Builder builder) {
origin = builder.origin;
@ -46,6 +55,7 @@ public final class CorsConfig {
allowedRequestMethods = builder.requestMethods;
allowedRequestHeaders = builder.requestHeaders;
allowNullOrigin = builder.allowNullOrigin;
preflightHeaders = builder.preflightHeaders;
}
/**
@ -69,6 +79,7 @@ public final class CorsConfig {
/**
* Web browsers may set the 'Origin' request header to 'null' if a resource is loaded
* from the local file system.
*
* If isNullOriginAllowed is true then the server will response with the wildcard for the
* the CORS response header 'Access-Control-Allow-Origin'.
*
@ -95,8 +106,8 @@ public final class CorsConfig {
* <li>Last-Modified</li>
* <li>Pragma</li>
* </ul>
* To expose other headers they need to be specified which what this method enables by adding the headers
* to the CORS 'Access-Control-Expose-Headers' response header.
* To expose other headers they need to be specified, which is what this method enables by
* adding the headers names to the CORS 'Access-Control-Expose-Headers' response header.
*
* @return {@code List<String>} a list of the headers to expose.
*/
@ -107,9 +118,17 @@ public final class CorsConfig {
/**
* Determines if cookies are supported for CORS requests.
*
* By default cookies are not included in CORS requests but if isCredentialsAllowed returns true cookies will
* be added to CORS requests. Setting this value to true will set the CORS 'Access-Control-Allow-Credentials'
* response header to true.
* By default cookies are not included in CORS requests but if isCredentialsAllowed returns
* true cookies will be added to CORS requests. Setting this value to true will set the
* CORS 'Access-Control-Allow-Credentials' response header to true.
*
* Please note that cookie support needs to be enabled on the client side as well.
* The client needs to opt-in to send cookies by calling:
* <pre>
* xhr.withCredentials = true;
* </pre>
* The default value for 'withCredentials' is false in which case no cookies are sent.
* Settning this to true will included cookies in cross origin requests.
*
* @return {@code true} if cookies are supported.
*/
@ -120,9 +139,10 @@ public final class CorsConfig {
/**
* Gets the maxAge setting.
*
* When making a preflight request the client has to perform two request with can be inefficient. This setting
* will set the CORS 'Access-Control-Max-Age' response header and enables the caching of the preflight response
* for the specified time. During this time no preflight request will be made.
* When making a preflight request the client has to perform two request with can be inefficient.
* This setting will set the CORS 'Access-Control-Max-Age' response header and enables the
* caching of the preflight response for the specified time. During this time no preflight
* request will be made.
*
* @return {@code long} the time in seconds that a preflight request may be cached.
*/
@ -132,10 +152,9 @@ public final class CorsConfig {
/**
* Returns the allowed set of Request Methods. The Http methods that should be returned in the
*
* CORS 'Access-Control-Request-Method' response header.
*
* @return {@code Set} strings that represent the allowed Request Methods.
* @return {@code Set} of {@link HttpMethod}s that represent the allowed Request Methods.
*/
public Set<HttpMethod> allowedRequestMethods() {
return Collections.unmodifiableSet(allowedRequestMethods);
@ -144,15 +163,45 @@ public final class CorsConfig {
/**
* Returns the allowed set of Request Headers.
*
* The header names returned from this method will be used to set the CORS 'Access-Control-Allow-Headers'
* response header.
* The header names returned from this method will be used to set the CORS
* 'Access-Control-Allow-Headers' response header.
*
* @return {@code Set} of strings that represent the allowed Request Headers.
* @return {@code Set<String>} of strings that represent the allowed Request Headers.
*/
public Set<String> allowedRequestHeaders() {
return Collections.unmodifiableSet(allowedRequestHeaders);
}
/**
* Returns HTTP response headers that should be added to a CORS preflight response.
*
* @return {@link HttpHeaders} the HTTP response headers to be added.
*/
public HttpHeaders preflightResponseHeaders() {
if (preflightHeaders.isEmpty()) {
return HttpHeaders.EMPTY_HEADERS;
}
final HttpHeaders preflightHeaders = new DefaultHttpHeaders();
for (Entry<CharSequence, Callable<?>> entry : this.preflightHeaders.entrySet()) {
final Object value = getValue(entry.getValue());
if (value instanceof Iterable) {
preflightHeaders.add(entry.getKey(), (Iterable<?>) value);
} else {
preflightHeaders.add(entry.getKey(), value);
}
}
return preflightHeaders;
}
private static <T> T getValue(final Callable<T> callable) {
try {
return callable.call();
} catch (final Exception e) {
throw new IllegalStateException("Could not generate value for callable [" + callable + ']', e);
}
}
@Override
public String toString() {
return StringUtil.simpleClassName(this) + "[enabled=" + enabled +
", origin=" + origin +
@ -160,17 +209,31 @@ public final class CorsConfig {
", isCredentialsAllowed=" + allowCredentials +
", maxAge=" + maxAge +
", allowedRequestMethods=" + allowedRequestMethods +
", allowedRequestHeaders=" + allowedRequestHeaders + ']';
", allowedRequestHeaders=" + allowedRequestHeaders +
", preflightHeaders=" + preflightHeaders + ']';
}
/**
* Creates a Builder instance with it's origin set to '*'.
*
* @return Builder to support method chaining.
*/
public static Builder anyOrigin() {
return new Builder("*");
}
/**
* Creates a {@link Builder} instance with the specified origin.
*
* @return {@link Builder} to support method chaining.
*/
public static Builder withOrigin(final String origin) {
return new Builder(origin);
}
/**
* Builder used to configure and build a CorsConfig instance.
*/
public static class Builder {
private final String origin;
@ -181,49 +244,254 @@ public final class CorsConfig {
private long maxAge;
private final Set<HttpMethod> requestMethods = new HashSet<HttpMethod>();
private final Set<String> requestHeaders = new HashSet<String>();
private final Map<CharSequence, Callable<?>> preflightHeaders = new HashMap<CharSequence, Callable<?>>();
private boolean noPreflightHeaders;
/**
* Creates a new Builder instance with the origin passed in.
*
* @param origin the origin to be used for this builder.
*/
public Builder(final String origin) {
this.origin = origin;
}
/**
* Web browsers may set the 'Origin' request header to 'null' if a resource is loaded
* from the local file system. Calling this method will enable a successful CORS response
* with a wildcard for the the CORS response header 'Access-Control-Allow-Origin'.
*
* @return {@link Builder} to support method chaining.
*/
public Builder allowNullOrigin() {
allowNullOrigin = true;
return this;
}
/**
* Disables CORS support.
*
* @return {@link Builder} to support method chaining.
*/
public Builder disable() {
enabled = false;
return this;
}
/**
* Specifies the headers to be exposed to calling clients.
*
* During a simple CORS request, only certain response headers are made available by the
* browser, for example using:
* <pre>
* xhr.getResponseHeader("Content-Type");
* </pre>
*
* The headers that are available by default are:
* <ul>
* <li>Cache-Control</li>
* <li>Content-Language</li>
* <li>Content-Type</li>
* <li>Expires</li>
* <li>Last-Modified</li>
* <li>Pragma</li>
* </ul>
*
* To expose other headers they need to be specified which is what this method enables by
* adding the headers to the CORS 'Access-Control-Expose-Headers' response header.
*
* @param headers the values to be added to the 'Access-Control-Expose-Headers' response header
* @return {@link Builder} to support method chaining.
*/
public Builder exposeHeaders(final String... headers) {
exposeHeaders.addAll(Arrays.asList(headers));
return this;
}
/**
* By default cookies are not included in CORS requests, but this method will enable cookies to
* be added to CORS requests. Calling this method will set the CORS 'Access-Control-Allow-Credentials'
* response header to true.
*
* Please note, that cookie support needs to be enabled on the client side as well.
* The client needs to opt-in to send cookies by calling:
* <pre>
* xhr.withCredentials = true;
* </pre>
* The default value for 'withCredentials' is false in which case no cookies are sent.
* Settning this to true will included cookies in cross origin requests.
*
* @return {@link Builder} to support method chaining.
*/
public Builder allowCredentials() {
allowCredentials = true;
return this;
}
/**
* When making a preflight request the client has to perform two request with can be inefficient.
* This setting will set the CORS 'Access-Control-Max-Age' response header and enables the
* caching of the preflight response for the specified time. During this time no preflight
* request will be made.
*
* @param max the maximum time, in seconds, that the preflight response may be cached.
* @return {@link Builder} to support method chaining.
*/
public Builder maxAge(final long max) {
maxAge = max;
return this;
}
/**
* Specifies the allowed set of HTTP Request Methods that should be returned in the
* CORS 'Access-Control-Request-Method' response header.
*
* @param methods the {@link HttpMethod}s that should be allowed.
* @return {@link Builder} to support method chaining.
*/
public Builder allowedRequestMethods(final HttpMethod... methods) {
requestMethods.addAll(Arrays.asList(methods));
return this;
}
/**
* Specifies the if headers that should be returned in the CORS 'Access-Control-Allow-Headers'
* response header.
*
* If a client specifies headers on the request, for example by calling:
* <pre>
* xhr.setRequestHeader('My-Custom-Header', "SomeValue");
* </pre>
* the server will recieve the above header name in the 'Access-Control-Request-Headers' of the
* preflight request. The server will then decide if it allows this header to be sent for the
* real request (remember that a preflight is not the real request but a request asking the server
* if it allow a request).
*
* @param headers the headers to be added to the preflight 'Access-Control-Allow-Headers' response header.
* @return {@link Builder} to support method chaining.
*/
public Builder allowedRequestHeaders(final String... headers) {
requestHeaders.addAll(Arrays.asList(headers));
return this;
}
/**
* Returns HTTP response headers that should be added to a CORS preflight response.
*
* An intermediary like a load balancer might require that a CORS preflight request
* have certain headers set. This enables such headers to be added.
*
* @param name the name of the HTTP header.
* @param values the values for the HTTP header.
* @return {@link Builder} to support method chaining.
*/
public Builder preflightResponseHeader(final CharSequence name, final Object... values) {
if (values.length == 1) {
preflightHeaders.put(name, new ConstantValueGenerator(values[0]));
} else {
preflightResponseHeader(name, Arrays.asList(values));
}
return this;
}
/**
* Returns HTTP response headers that should be added to a CORS preflight response.
*
* An intermediary like a load balancer might require that a CORS preflight request
* have certain headers set. This enables such headers to be added.
*
* @param name the name of the HTTP header.
* @param value the values for the HTTP header.
* @param <T> the type of values that the Iterable contains.
* @return {@link Builder} to support method chaining.
*/
public <T> Builder preflightResponseHeader(final CharSequence name, final Iterable<T> value) {
preflightHeaders.put(name, new ConstantValueGenerator(value));
return this;
}
/**
* Returns HTTP response headers that should be added to a CORS preflight response.
*
* An intermediary like a load balancer might require that a CORS preflight request
* have certain headers set. This enables such headers to be added.
*
* Some values must be dynamically created when the HTTP response is created, for
* example the 'Date' response header. This can be occomplished by using a Callable
* which will have its 'call' method invoked when the HTTP response is created.
*
* @param name the name of the HTTP header.
* @param valueGenerator a Callable which will be invoked at HTTP response creation.
* @param <T> the type of the value that the Callable can return.
* @return {@link Builder} to support method chaining.
*/
public <T> Builder preflightResponseHeader(final String name, final Callable<T> valueGenerator) {
preflightHeaders.put(name, valueGenerator);
return this;
}
/**
* Specifies that no preflight response headers should be added to a preflight response.
*
* @return {@link Builder} to support method chaining.
*/
public Builder noPreflightResponseHeaders() {
noPreflightHeaders = true;
return this;
}
/**
* Builds a {@link CorsConfig} with settings specified by previous method calls.
*
* @return {@link CorsConfig} the configured CorsConfig instance.
*/
public CorsConfig build() {
if (preflightHeaders.isEmpty() && !noPreflightHeaders) {
preflightHeaders.put(Names.DATE, new DateValueGenerator());
preflightHeaders.put(Names.CONTENT_LENGTH, new ConstantValueGenerator("0"));
}
return new CorsConfig(this);
}
}
/**
* This class is used for preflight HTTP response values that do not need to be
* generated, but instead the value is "static" in that the same value will be returned
* for each call.
*/
private static final class ConstantValueGenerator implements Callable<Object> {
private final Object value;
/**
* Sole constructor.
*
* @param value the value that will be returned when the call method is invoked.
*/
private ConstantValueGenerator(final Object value) {
if (value == null) {
throw new IllegalArgumentException("value must not be null");
}
this.value = value;
}
@Override
public Object call() {
return value;
}
}
/**
* This callable is used for the DATE preflight HTTP response HTTP header.
* It's value must be generated when the response is generated, hence will be
* different for every call.
*/
public static final class DateValueGenerator implements Callable<Date> {
@Override
public Date call() throws Exception {
return new Date();
}
}
}

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@ -15,10 +15,6 @@
*/
package io.netty.handler.codec.http.cors;
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.OK;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
@ -30,7 +26,9 @@ import io.netty.handler.codec.http.HttpResponse;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;
import java.util.Date;
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.
@ -64,16 +62,25 @@ public class CorsHandler extends ChannelDuplexHandler {
private void handlePreflight(final ChannelHandlerContext ctx, final HttpRequest request) {
final HttpResponse response = new DefaultHttpResponse(request.getProtocolVersion(), OK);
if (setOrigin(response)) {
HttpHeaders.setContentLength(response, 0);
HttpHeaders.setDate(response, new Date());
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) {

View File

@ -15,17 +15,16 @@
*/
package io.netty.handler.codec.http.cors;
import static io.netty.handler.codec.http.cors.CorsConfig.withOrigin;
import static io.netty.handler.codec.http.cors.CorsConfig.anyOrigin;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpHeaders.Names;
import io.netty.handler.codec.http.HttpMethod;
import org.junit.Test;
import static org.hamcrest.CoreMatchers.equalTo;
import static org.hamcrest.CoreMatchers.hasItems;
import static org.hamcrest.CoreMatchers.is;
import static io.netty.handler.codec.http.cors.CorsConfig.*;
import static org.hamcrest.CoreMatchers.*;
import static org.hamcrest.MatcherAssert.*;
public class CorsConfigurationTest {
public class CorsConfigTest {
@Test
public void disabled() {
@ -75,4 +74,34 @@ public class CorsConfigurationTest {
assertThat(cors.allowedRequestHeaders(), hasItems("preflight-header1", "preflight-header2"));
}
@Test
public void preflightResponseHeadersSingleValue() {
final CorsConfig cors = withOrigin("*").preflightResponseHeader("SingleValue", "value").build();
assertThat(cors.preflightResponseHeaders().get("SingleValue"), equalTo("value"));
}
@Test
public void preflightResponseHeadersMultipleValues() {
final CorsConfig cors = withOrigin("*").preflightResponseHeader("MultipleValues", "value1", "value2").build();
assertThat(cors.preflightResponseHeaders().getAll("MultipleValues"), hasItems("value1", "value2"));
}
@Test
public void defaultPreflightResponseHeaders() {
final CorsConfig cors = withOrigin("*").build();
assertThat(cors.preflightResponseHeaders().get(Names.DATE), is(notNullValue()));
assertThat(cors.preflightResponseHeaders().get(Names.CONTENT_LENGTH), is("0"));
}
@Test
public void emptyPreflightResponseHeaders() {
final CorsConfig cors = withOrigin("*").noPreflightResponseHeaders().build();
assertThat(cors.preflightResponseHeaders(), equalTo(HttpHeaders.EMPTY_HEADERS));
}
@Test (expected = IllegalArgumentException.class)
public void shouldThrowIfValueIsNull() {
withOrigin("*").preflightResponseHeader("HeaderName", null).build();
}
}

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@ -15,17 +15,9 @@
*/
package io.netty.handler.codec.http.cors;
import static io.netty.handler.codec.http.HttpHeaders.Names.*;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;
import static io.netty.handler.codec.http.HttpMethod.GET;
import static io.netty.handler.codec.http.HttpMethod.OPTIONS;
import static org.hamcrest.CoreMatchers.*;
import static org.hamcrest.MatcherAssert.assertThat;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.handler.codec.http.DefaultFullHttpRequest;
import io.netty.handler.codec.http.DefaultHttpResponse;
import io.netty.handler.codec.http.FullHttpRequest;
@ -34,6 +26,15 @@ import io.netty.handler.codec.http.HttpResponse;
import io.netty.handler.codec.http.HttpResponseStatus;
import org.junit.Test;
import java.util.Arrays;
import java.util.concurrent.Callable;
import static io.netty.handler.codec.http.HttpHeaders.Names.*;
import static io.netty.handler.codec.http.HttpMethod.*;
import static io.netty.handler.codec.http.HttpVersion.*;
import static org.hamcrest.CoreMatchers.*;
import static org.hamcrest.MatcherAssert.*;
public class CorsHandlerTest {
@Test
@ -77,6 +78,54 @@ public class CorsHandlerTest {
assertThat(response.headers().getAll(ACCESS_CONTROL_ALLOW_HEADERS), hasItems("content-type", "xheader1"));
}
@Test
public void preflightRequestWithDefaultHeaders() {
final CorsConfig config = CorsConfig.withOrigin("http://localhost:8888").build();
final HttpResponse response = preflightRequest(config, "http://localhost:8888", "content-type, xheader1");
assertThat(response.headers().get(CONTENT_LENGTH), is("0"));
assertThat(response.headers().get(DATE), is(notNullValue()));
}
@Test
public void preflightRequestWithCustomHeader() {
final CorsConfig config = CorsConfig.withOrigin("http://localhost:8888")
.preflightResponseHeader("CustomHeader", "somevalue")
.build();
final HttpResponse response = preflightRequest(config, "http://localhost:8888", "content-type, xheader1");
assertThat(response.headers().get("CustomHeader"), equalTo("somevalue"));
}
@Test
public void preflightRequestWithCustomHeaders() {
final CorsConfig config = CorsConfig.withOrigin("http://localhost:8888")
.preflightResponseHeader("CustomHeader", "value1", "value2")
.build();
final HttpResponse response = preflightRequest(config, "http://localhost:8888", "content-type, xheader1");
assertThat(response.headers().getAll("CustomHeader"), hasItems("value1", "value2"));
}
@Test
public void preflightRequestWithCustomHeadersIterable() {
final CorsConfig config = CorsConfig.withOrigin("http://localhost:8888")
.preflightResponseHeader("CustomHeader", Arrays.asList("value1", "value2"))
.build();
final HttpResponse response = preflightRequest(config, "http://localhost:8888", "content-type, xheader1");
assertThat(response.headers().getAll("CustomHeader"), hasItems("value1", "value2"));
}
@Test
public void preflightRequestWithValueGenerator() {
final CorsConfig config = CorsConfig.withOrigin("http://localhost:8888")
.preflightResponseHeader("GenHeader", new Callable<String>() {
@Override
public String call() throws Exception {
return "generatedValue";
}
}).build();
final HttpResponse response = preflightRequest(config, "http://localhost:8888", "content-type, xheader1");
assertThat(response.headers().get("GenHeader"), equalTo("generatedValue"));
}
@Test
public void preflightRequestWithNullOrigin() {
final String origin = "null";