#33 - ControllerLinkBuilder now regards X-Forwarded-Host header.

When setting up the builder we now set the host to the value held in the X-Forwarded-Host [0] header if present. This allows to render appropriate URIs in reverse proxy scenarios. This is essentially an extension of ServletUriComponentsBuilder that will be fixed in there eventually. See SPR-10110 [1] for details.

[0] http://tools.ietf.org/html/draft-ietf-appsawg-http-forwarded-10
[1] https://jira.springsource.org/browse/SPR-10110

Author: odrotbohm

src/main/java/org/springframework/hateoas/mvc/ControllerLinkBuilder.java

@@ -21,6 +21,8 @@
 import java.util.Iterator;
 import java.util.Map;
 
+import javax.servlet.http.HttpServletRequest;
+
 import org.aopalliance.intercept.MethodInvocation;
 import org.springframework.hateoas.Link;
 import org.springframework.hateoas.core.AnnotationAttribute;
@@ -30,8 +32,12 @@
 import org.springframework.hateoas.core.LinkBuilderSupport;
 import org.springframework.hateoas.core.MappingDiscoverer;
 import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.context.request.RequestAttributes;
+import org.springframework.web.context.request.RequestContextHolder;
+import org.springframework.web.context.request.ServletRequestAttributes;
 import org.springframework.web.servlet.support.ServletUriComponentsBuilder;
 import org.springframework.web.util.UriComponentsBuilder;
 import org.springframework.web.util.UriTemplate;
@@ -79,7 +85,7 @@ public static ControllerLinkBuilder linkTo(Class<?> controller, Object... parame
 
 		Assert.notNull(controller);
 
-		ControllerLinkBuilder builder = new ControllerLinkBuilder(ServletUriComponentsBuilder.fromCurrentServletMapping());
+		ControllerLinkBuilder builder = new ControllerLinkBuilder(getBuilder());
 		String mapping = DISCOVERER.getMapping(controller);
 
 		if (mapping == null) {
@@ -95,7 +101,7 @@ public static ControllerLinkBuilder linkTo(Method method, Object... parameters)
 
 		UriTemplate template = new UriTemplate(DISCOVERER.getMapping(method));
 		URI uri = template.expand(parameters);
-		return new ControllerLinkBuilder(ServletUriComponentsBuilder.fromCurrentServletMapping()).slash(uri);
+		return new ControllerLinkBuilder(getBuilder()).slash(uri);
 	}
 
 	/**
@@ -141,7 +147,7 @@ public static ControllerLinkBuilder linkTo(Object invocationValue) {
 		values.putAll(accessor.getBoundParameters(invocation));
 		URI uri = template.expand(values);
 
-		return new ControllerLinkBuilder(ServletUriComponentsBuilder.fromCurrentServletMapping()).slash(uri);
+		return new ControllerLinkBuilder(getBuilder()).slash(uri);
 	}
 
 	/**
@@ -173,4 +179,38 @@ protected ControllerLinkBuilder getThis() {
 	protected ControllerLinkBuilder createNewInstance(UriComponentsBuilder builder) {
 		return new ControllerLinkBuilder(builder);
 	}
+
+	/**
+	 * Returns a {@link UriComponentsBuilder} obtained from the current servlet mapping with the host tweaked in case the
+	 * request contains an {@code X-Forwarded-Host} header.
+	 * 
+	 * @return
+	 */
+	private static UriComponentsBuilder getBuilder() {
+
+		HttpServletRequest request = getCurrentRequest();
+		ServletUriComponentsBuilder builder = ServletUriComponentsBuilder.fromServletMapping(request);
+
+		String header = request.getHeader("X-Forwarded-Host");
+		if (StringUtils.hasText(header)) {
+			builder.host(header);
+		}
+
+		return builder;
+	}
+
+	/**
+	 * Copy of {@link ServletUriComponentsBuilder#getCurrentRequest()} until SPR-10110 gets fixed.
+	 * 
+	 * @return
+	 */
+	private static HttpServletRequest getCurrentRequest() {
+
+		RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
+		Assert.state(requestAttributes != null, "Could not find current request via RequestContextHolder");
+		Assert.isInstanceOf(ServletRequestAttributes.class, requestAttributes);
+		HttpServletRequest servletRequest = ((ServletRequestAttributes) requestAttributes).getRequest();
+		Assert.state(servletRequest != null, "Could not find current HttpServletRequest");
+		return servletRequest;
+	}
 }

src/test/java/org/springframework/hateoas/TestUtils.java

@@ -18,8 +18,6 @@
 import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 
-import javax.servlet.http.HttpServletRequest;
-
 import org.junit.Before;
 import org.springframework.mock.web.MockHttpServletRequest;
 import org.springframework.web.context.request.RequestContextHolder;
@@ -32,10 +30,12 @@
  */
 public class TestUtils {
 
+	protected MockHttpServletRequest request;
+
 	@Before
 	public void setUp() {
 
-		HttpServletRequest request = new MockHttpServletRequest();
+		request = new MockHttpServletRequest();
 		ServletRequestAttributes requestAttributes = new ServletRequestAttributes(request);
 		RequestContextHolder.setRequestAttributes(requestAttributes);
 	}

src/test/java/org/springframework/hateoas/mvc/ControllerLinkBuilderUnitTest.java

@@ -17,11 +17,11 @@
 
 import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
-import static org.mockito.Mockito.*;
 import static org.springframework.hateoas.mvc.ControllerLinkBuilder.*;
 
 import org.hamcrest.Matchers;
 import org.junit.Test;
+import org.mockito.Mockito;
 import org.springframework.hateoas.Identifiable;
 import org.springframework.hateoas.Link;
 import org.springframework.hateoas.TestUtils;
@@ -48,23 +48,23 @@ public void createsLinkToParameterizedControllerRoot() {
 
 		Link link = linkTo(PersonsAddressesController.class, 15).withSelfRel();
 		assertThat(link.getRel(), is(Link.REL_SELF));
-		assertThat(link.getHref(), Matchers.endsWith("/people/15/addresses"));
+		assertThat(link.getHref(), endsWith("/people/15/addresses"));
 	}
 
 	@Test
 	public void createsLinkToSubResource() {
 
 		Link link = linkTo(PersonControllerImpl.class).slash("something").withSelfRel();
 		assertThat(link.getRel(), is(Link.REL_SELF));
-		assertThat(link.getHref(), Matchers.endsWith("/people/something"));
+		assertThat(link.getHref(), endsWith("/people/something"));
 	}
 
 	@Test
 	public void createsLinkWithCustomRel() {
 
 		Link link = linkTo(PersonControllerImpl.class).withRel(Link.REL_NEXT);
 		assertThat(link.getRel(), is(Link.REL_NEXT));
-		assertThat(link.getHref(), Matchers.endsWith("/people"));
+		assertThat(link.getHref(), endsWith("/people"));
 	}
 
 	@Test(expected = IllegalStateException.class)
@@ -81,35 +81,47 @@ public void createsLinkToUnmappedController() {
 	@SuppressWarnings("unchecked")
 	public void usesIdOfIdentifyableForPathSegment() {
 
-		Identifiable<Long> identifyable = mock(Identifiable.class);
-		when(identifyable.getId()).thenReturn(10L);
+		Identifiable<Long> identifyable = Mockito.mock(Identifiable.class);
+		Mockito.when(identifyable.getId()).thenReturn(10L);
 
 		Link link = linkTo(PersonControllerImpl.class).slash(identifyable).withSelfRel();
-		assertThat(link.getHref(), Matchers.endsWith("/people/10"));
+		assertThat(link.getHref(), endsWith("/people/10"));
 	}
 
 	@Test
 	public void appendingNullIsANoOp() {
 
 		Link link = linkTo(PersonControllerImpl.class).slash(null).withSelfRel();
-		assertThat(link.getHref(), Matchers.endsWith("/people"));
+		assertThat(link.getHref(), endsWith("/people"));
 
 		link = linkTo(PersonControllerImpl.class).slash((Object) null).withSelfRel();
-		assertThat(link.getHref(), Matchers.endsWith("/people"));
+		assertThat(link.getHref(), endsWith("/people"));
 	}
 
 	@Test
 	public void linksToMethod() {
 
 		Link link = linkTo(methodOn(ControllerWithMethods.class).myMethod(null)).withSelfRel();
-		assertThat(link.getHref(), Matchers.endsWith("/something/else"));
+		assertThat(link.getHref(), endsWith("/something/else"));
 	}
 
 	@Test
 	public void linksToMethodWithPathVariable() {
 
 		Link link = linkTo(methodOn(ControllerWithMethods.class).methodWithPathVariable("1")).withSelfRel();
-		assertThat(link.getHref(), Matchers.endsWith("/something/1/foo"));
+		assertThat(link.getHref(), endsWith("/something/1/foo"));
+	}
+
+	/**
+	 * @see #33
+	 */
+	@Test
+	public void usesForwardedHostAsHostIfHeaderIsSet() {
+
+		request.addHeader("X-Forwarded-Host", "somethingDifferent");
+
+		Link link = linkTo(PersonControllerImpl.class).withSelfRel();
+		assertThat(link.getHref(), startsWith("http://somethingDifferent"));
 	}
 
 	static class Person implements Identifiable<Long> {

template.mf

@@ -5,6 +5,7 @@ Bundle-ManifestVersion: 2
 Import-Template:
  com.fasterxml.jackson.*;version="${jackson2.version:[=.=.=,+1.0.0)}";resolution:=optional,
  com.jayway.jsonpath.*;version="${jsonpath.version:[=.=.=,+1.0.0)}";resolution:=optional,
+ javax.servlet.*;version="[2.5,4.0)";resolution:=optional,
  javax.ws.rs.*;version="${jaxrs.version:[=.=.=,+1.0.0)}";resolution:=optional,
  javax.xml.bind.*;version="0",
  net.minidev.json.*;version="${minidevjson.version:[=.=.=,+1.0.0)}";resolution:=optional,