Initial sketch of a solution for zalando#172. We do not have a good w…

…ay of testing against 2.5 in the build yet, suggestions welcome :)

logbook-servlet/src/main/java/org/zalando/logbook/servlet/AsyncHelper.java

@@ -0,0 +1,63 @@
+package org.zalando.logbook.servlet;
+
+import javax.servlet.http.HttpServletRequest;
+import java.lang.reflect.InvocationTargetException;
+import java.util.Arrays;
+import java.util.Objects;
+import java.util.Optional;
+
+/**
+ * Reflection here is used to support both Servlet API 2.5 and 3.0 in the same code base.
+ */
+public class AsyncHelper {
+
+    public static boolean isFirstRequest(HttpServletRequest request) {
+        return dispatcherTypeClass()
+                .map(theClass -> isAsyncDispatcherType(request, theClass))
+                .orElse(true);
+    }
+
+    public static boolean isLastRequest(final HttpServletRequest request) {
+        return dispatcherTypeClass().isPresent() && !isAsyncStarted(request);
+    }
+
+    public static void setDispatcherTypeAsync(final HttpServletRequest request) {
+        dispatcherTypeClass().ifPresent(dispatcherTypeClass -> {
+            Object asyncDispatcherType = enumConstant(dispatcherTypeClass, "ASYNC");
+            invoke(request, "setDispatcherType", void.class, new Object[]{asyncDispatcherType}, dispatcherTypeClass);
+        });
+    }
+
+    private static boolean isAsyncDispatcherType(HttpServletRequest request, Class<?> dispatcherTypeClass) {
+        Object dispatcherType = invoke(request, "getDispatcherType", Object.class, new Object[]{});
+        Object asyncDispatcherType = enumConstant(dispatcherTypeClass, "ASYNC");
+        return !Objects.equals(dispatcherType, asyncDispatcherType);
+    }
+
+    private static boolean isAsyncStarted(HttpServletRequest request) {
+        return invoke(request, "isAsyncStarted", Boolean.class, new Object[]{});
+    }
+
+    private static <T> T invoke(HttpServletRequest request, String methodName, Class<T> returnType, Object[] arguments, Class<?>... parameterTypes) {
+        try {
+            return returnType.cast(request.getClass().getMethod(methodName, parameterTypes).invoke(request, arguments));
+        } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    private static Object enumConstant(Class<?> dispatcherType, String name) {
+        return Arrays.stream(dispatcherType.getEnumConstants())
+                .filter(constant -> constant.toString().equals(name))
+                .findFirst()
+                .orElseThrow(() -> new IllegalStateException("Could not find DispatcherType." + name));
+    }
+
+    private static Optional<Class<?>> dispatcherTypeClass() {
+        try {
+            return Optional.of(Class.forName("javax.servlet.DispatcherType"));
+        } catch (ClassNotFoundException e) {
+            return Optional.empty();
+        }
+    }
+}

logbook-servlet/src/main/java/org/zalando/logbook/servlet/LocalResponse.java

@@ -1,22 +1,20 @@
 package org.zalando.logbook.servlet;
 
-import org.zalando.logbook.HttpResponse;
-import org.zalando.logbook.Origin;
-import org.zalando.logbook.RawHttpResponse;
-
-import javax.servlet.ServletOutputStream;
-import javax.servlet.http.HttpServletResponse;
-import javax.servlet.http.HttpServletResponseWrapper;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
 import java.nio.charset.Charset;
-import java.util.List;
-import java.util.Map;
-import java.util.Optional;
+import java.util.*;
 import java.util.function.Supplier;
+import javax.servlet.ServletOutputStream;
+import javax.servlet.http.HttpServletResponse;
+import javax.servlet.http.HttpServletResponseWrapper;
+
+import org.zalando.logbook.HttpResponse;
+import org.zalando.logbook.Origin;
+import org.zalando.logbook.RawHttpResponse;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 
@@ -27,6 +25,16 @@ final class LocalResponse extends HttpServletResponseWrapper implements RawHttpR
     private boolean withBody;
     private Tee tee;
 
+    /**
+     * All the code connected to this field is to allow for compatibility with Servlet API 2.5
+     */
+    private int status = 200;
+
+    /**
+     * All the code connected to this field is to allow for compatibility with Servlet API 2.5
+     */
+    private Map<String, List<String>> headers = new HashMap<>();
+
     LocalResponse(final HttpServletResponse response, final String protocolVersion) throws IOException {
         super(response);
         this.protocolVersion = protocolVersion;
@@ -46,11 +54,9 @@ public String getProtocolVersion() {
     @Override
     public Map<String, List<String>> getHeaders() {
         final HeadersBuilder builder = new HeadersBuilder();
-
-        for (final String header : getHeaderNames()) {
-            builder.put(header, getHeaders(header));
+        for (final String header : headers.keySet()) {
+            builder.put(header, headers.get(header));
         }
-
         return builder.build();
     }
 
@@ -108,6 +114,77 @@ private Tee tee() throws IOException {
         return tee;
     }
 
+    @Override
+    public int getStatus() {
+        return status;
+    }
+
+    @Override
+    public void setStatus(int status) {
+        this.status = status;
+        super.setStatus(status);
+    }
+
+    @Override
+    public void sendError(int status) throws IOException {
+        this.status = status;
+        super.sendError(status);
+    }
+
+    @Override
+    public void sendError(int status, String msg) throws IOException {
+        this.status = status;
+        super.sendError(status, msg);
+    }
+
+    @Override
+    public void addDateHeader(String name, long date) {
+        super.addDateHeader(name, date);
+        addMultiMapHeader(name, new Date(date).toString()); // TODO: this is dodgy, but in 2.5 we do not have super.getHeader
+    }
+
+    @Override
+    public void addHeader(String name, String value) {
+        super.addHeader(name, value);
+        addMultiMapHeader(name, value);
+    }
+
+    @Override
+    public void addIntHeader(String name, int value) {
+        super.addIntHeader(name, value);
+        addMultiMapHeader(name, String.valueOf(value));
+    }
+
+    @Override
+    public void setHeader(String name, String value) {
+        super.setHeader(name, value);
+        setMultiMapHeader(name, value);
+    }
+
+    @Override
+    public void setDateHeader(String name, long date) {
+        super.setDateHeader(name, date);
+        setMultiMapHeader(name, new Date(date).toString()); // TODO: this is dodgy, but in 2.5 we do not have super.getHeader
+    }
+
+    @Override
+    public void setIntHeader(String name, int value) {
+        super.setIntHeader(name, value);
+        setMultiMapHeader(name, String.valueOf(value));
+    }
+
+    private void addMultiMapHeader(String name, String value) {
+        List<String> values = headers.computeIfAbsent(name, key -> new ArrayList<>());
+        values.add(value);
+    }
+
+    private void setMultiMapHeader(String name, String value) {
+        headers.remove(name);
+        ArrayList<String> values = new ArrayList<>();
+        values.add(value);
+        headers.put(name, values);
+    }
+
     private static class Tee {
 
         private final ByteArrayOutputStream branch;

logbook-servlet/src/main/java/org/zalando/logbook/servlet/NormalStrategy.java

@@ -13,11 +13,15 @@
 import java.util.Optional;
 import java.util.function.Consumer;
 
-import static javax.servlet.RequestDispatcher.ERROR_EXCEPTION_TYPE;
 import static org.zalando.logbook.servlet.Attributes.CORRELATOR;
 
 final class NormalStrategy implements Strategy {
 
+    /**
+     * Do not use RequestDispatcher.ERROR_EXCEPTION_TYPE, since Servlet API 2.5 does not have this constant.
+     */
+    private static final String JAVAX_SERVLET_ERROR_EXCEPTION_TYPE = "javax.servlet.error.exception_type";
+
     private final RawRequestFilter filter;
 
     NormalStrategy(final RawRequestFilter filter) {
@@ -55,7 +59,7 @@ private Optional<Correlator> logRequestIfNecessary(final Logbook logbook,
     }
 
     private RawHttpRequest skipBodyIfErrorDispatch(final RemoteRequest request) {
-        if (request.getAttribute(ERROR_EXCEPTION_TYPE) == null) {
+        if (request.getAttribute(JAVAX_SERVLET_ERROR_EXCEPTION_TYPE) == null) {
             return request;
         }
         return filter.filter(request);

logbook-servlet/src/main/java/org/zalando/logbook/servlet/RemoteRequest.java

@@ -69,6 +69,7 @@ public String getQuery() {
         return Optional.ofNullable(getQueryString()).orElse("");
     }
 
+    @SuppressWarnings("unchecked") // warnings appear when using Servlet API 2.5
     @Override
     public Map<String, List<String>> getHeaders() {
         final HeadersBuilder builder = new HeadersBuilder();

logbook-servlet/src/main/java/org/zalando/logbook/servlet/SecurityStrategy.java

@@ -46,7 +46,7 @@ public void doFilter(final Logbook logbook, final HttpServletRequest httpRequest
         }
     }
 
-    private boolean isUnauthorized(final HttpServletResponse response) {
+    private boolean isUnauthorized(final LocalResponse response) {
         return response.getStatus() == 401;
     }
 

logbook-servlet/src/main/java/org/zalando/logbook/servlet/Strategy.java

@@ -2,7 +2,6 @@
 
 import org.zalando.logbook.Logbook;
 
-import javax.servlet.DispatcherType;
 import javax.servlet.FilterChain;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
@@ -20,13 +19,11 @@ void doFilter(final Logbook logbook, final HttpServletRequest httpRequest, final
             final FilterChain chain) throws ServletException, IOException;
 
     default boolean isFirstRequest(final HttpServletRequest request) {
-        return request.getDispatcherType() != DispatcherType.ASYNC;
+        return AsyncHelper.isFirstRequest(request);
     }
 
     default boolean isLastRequest(final HttpServletRequest request) {
-        return !request.isAsyncStarted();
+        return AsyncHelper.isLastRequest(request);
     }
-
-
 }
 

logbook-servlet/src/test/java/org/zalando/logbook/servlet/LocalResponseTest.java

@@ -8,7 +8,9 @@
 import java.io.IOException;
 import java.io.PrintWriter;
 
+import static java.util.Collections.singletonList;
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.hasEntry;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.nullValue;
 import static org.junit.jupiter.api.Assertions.assertNotSame;
@@ -120,4 +122,86 @@ void shouldReturnNullContentTypeWhenNoContentTypeHasBeenSpecified() {
 
         assertThat(unit.getContentType(), is(nullValue()));
     }
+
+    @Test
+    void defaultStatusIs200() {
+        assertThat(unit.getStatus(), is(200));
+    }
+
+    @Test
+    void shouldSetStatus() {
+        unit.setStatus(300);
+
+        verify(mock).setStatus(300);
+        assertThat(unit.getStatus(), is(300));
+    }
+
+    @Test
+    void shouldSendErrorWithNoMessage() throws IOException {
+        unit.sendError(403);
+
+        verify(mock).sendError(403);
+        assertThat(unit.getStatus(), is(403));
+    }
+
+    @Test
+    void shouldSendErrorWithAMessage() throws IOException {
+        unit.sendError(403, "There is an error");
+
+        verify(mock).sendError(403, "There is an error");
+        assertThat(unit.getStatus(), is(403));
+    }
+
+    @Test
+    void shouldAddDateHeader() {
+        unit.addDateHeader("date", 111111);
+
+        verify(mock).addDateHeader("date", 111111);
+        assertThat(unit.getHeaders(), hasEntry("date", singletonList("Thu Jan 01 01:01:51 GMT 1970")));
+    }
+
+    @Test
+    void shouldAddHeader() {
+        unit.addHeader("example", "value");
+
+        verify(mock).addHeader("example", "value");
+        assertThat(unit.getHeaders(), hasEntry("example", singletonList("value")));
+    }
+
+    @Test
+    void shouldAddIntegerHeader() {
+        unit.addIntHeader("example", 123);
+
+        verify(mock).addIntHeader("example", 123);
+        assertThat(unit.getHeaders(), hasEntry("example", singletonList("123")));
+    }
+
+    @Test
+    void shouldSetHeader() {
+        unit.addHeader("example", "first value");
+        unit.setHeader("example", "Overwritten value");
+
+
+        verify(mock).setHeader("example", "Overwritten value");
+        assertThat(unit.getHeaders(), hasEntry("example", singletonList("Overwritten value")));
+    }
+
+    @Test
+    void shouldSetDateHeader() {
+        unit.addDateHeader("example", 111111);
+        unit.setDateHeader("example", 333333);
+
+        verify(mock).setDateHeader("example", 333333);
+        assertThat(unit.getHeaders(), hasEntry("example", singletonList("Thu Jan 01 01:05:33 GMT 1970")));
+    }
+
+    @Test
+    void shouldSetIntegerHeader() {
+        unit.addIntHeader("example", 111);
+        unit.setIntHeader("example", 4546);
+
+
+        verify(mock).setIntHeader("example", 4546);
+        assertThat(unit.getHeaders(), hasEntry("example", singletonList("4546")));
+    }
 }

logbook-servlet/src/test/java/org/zalando/logbook/servlet/RequestBuilders.java

@@ -4,7 +4,6 @@
 import org.springframework.test.web.servlet.MvcResult;
 import org.springframework.test.web.servlet.RequestBuilder;
 
-import javax.servlet.DispatcherType;
 
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.asyncDispatch;
 
@@ -16,7 +15,7 @@ static RequestBuilder async(final MvcResult result) {
         return context -> {
             final MockHttpServletRequest request = builder.buildRequest(context);
             // this is missing in MockMvcRequestBuilders#asyncDispatch
-            request.setDispatcherType(DispatcherType.ASYNC);
+            AsyncHelper.setDispatcherTypeAsync(request);
             return request;
         };
     }

pom.xml

@@ -452,6 +452,10 @@
                                 <goal>check</goal>
                             </goals>
                             <configuration>
+                                <excludes>
+                                    <!-- This can never have full coverage in one run since some branches are dependent on the Servlet API on the classpath -->
+                                    <exclude>org/zalando/logbook/servlet/AsyncHelper*</exclude>
+                                </excludes>
                                 <rules>
                                     <rule>
                                         <element>CLASS</element>