CXF-9192: Inconsistent best effort read of body by web-client when protocol is HTTP/2

Author: reta

rt/transports/http/src/main/java/org/apache/cxf/transport/http/HttpClientHTTPConduit.java

@@ -1147,6 +1147,7 @@ protected void updateResponseHeaders(Message inMessage) throws IOException {
         }
 
         @Override
+        @SuppressWarnings("checkstyle:NestedIfDepth")
         protected InputStream getInputStream() throws IOException {
             HttpResponse<InputStream> resp = getResponse();
             String method = (String)outMessage.get(Message.HTTP_REQUEST_METHOD);
@@ -1172,9 +1173,24 @@ protected InputStream getInputStream() throws IOException {
                     }
                 } else if (!fChunk.isPresent() || !"chunked".equals(fChunk.get())) {
                     if (resp.version() == Version.HTTP_2) {
-                        InputStream in = resp.body();
+                        final InputStream in = resp.body();
+                        // The InputStream::available is a best effort, if it returns 0, issuing
+                        // the InputStream::read will either block if data is expected or return
+                        // immediately
                         if (in.available() <= 0) {
-                            try (in) {
+                            final PushbackInputStream pbin = new PushbackInputStream(in);
+                            try {
+                                // HttpResponseInputStream will block if there is data to be read
+                                final int c = pbin.read();
+                                if (c != -1) {
+                                    pbin.unread((byte) c);
+                                    return new HttpClientFilteredInputStream(pbin);
+                                }
+                            } catch (final IOException ex) {
+                                // ignore
+                            }
+
+                            try (pbin) {
                                 return null;
                             }
                         }

systests/transports/src/test/java/org/apache/cxf/systest/http2_jetty/AbstractJettyClientServerHttp2Test.java

@@ -21,6 +21,7 @@
 
 import jakarta.ws.rs.core.Response;
 import org.apache.cxf.configuration.jsse.TLSClientParameters;
+import org.apache.cxf.jaxrs.client.ClientConfiguration;
 import org.apache.cxf.jaxrs.client.WebClient;
 import org.apache.cxf.systest.http2_jetty.Http2TestClient.ClientResponse;
 import org.apache.cxf.testutil.common.AbstractBusClientServerTestBase;
@@ -108,6 +109,36 @@ public void testBookWithHttp() throws Exception {
             assertEquals("CXF in Action", resp.readEntity(String.class));
         }
     }
+    
+    @Test
+    public void testBookWithHttp2Redirect() throws Exception {
+        final WebClient wc = WebClient
+            .create(getAddress() + getContext() + "/web/bookstore/redirect")
+            .accept("application/xml");
+        
+        final ClientConfiguration config = WebClient.getConfig(wc);
+        config.getRequestContext().put(HTTPConduit.FORCE_HTTP_VERSION, "2");
+        config.getHttpConduit().getClient().setAutoRedirect(false);
+
+        if (isSecure()) {
+            final HTTPConduit conduit = WebClient.getConfig(wc).getHttpConduit();
+            TLSClientParameters params = conduit.getTlsClientParameters();
+
+            if (params == null)  {
+                params = new TLSClientParameters();
+                conduit.setTlsClientParameters(params);
+            }
+
+            // Create TrustManager instance which trusts all clients and servers
+            params.setTrustManagers(InsecureTrustManager.getNoOpX509TrustManagers()); 
+            params.setDisableCNCheck(true);
+        }
+        
+        try (Response resp = wc.get()) {
+            assertThat(resp.getStatus(), equalTo(307));
+            assertEquals("Error while getting books", resp.readEntity(String.class));
+        }
+    }
 
     protected abstract String getAddress();
     protected abstract String getContext();

systests/transports/src/test/java/org/apache/cxf/systest/http2_jetty/BookStore.java

@@ -20,12 +20,20 @@
 package org.apache.cxf.systest.http2_jetty;
 
 import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.LockSupport;
 
 import jakarta.ws.rs.GET;
 import jakarta.ws.rs.Path;
 import jakarta.ws.rs.Produces;
+import jakarta.ws.rs.core.Context;
+import jakarta.ws.rs.core.Response;
+import jakarta.ws.rs.core.StreamingOutput;
+import jakarta.ws.rs.core.UriInfo;
 import org.apache.cxf.jaxrs.ext.StreamingResponse;
 
 @Path("/web/bookstore")
@@ -39,6 +47,23 @@ public byte[] getBookName() {
         return "CXF in Action".getBytes();
     }
 
+    @GET
+    @Path("/redirect")
+    @Produces("application/xml")
+    public Response redirect(@Context final UriInfo info) {
+        return Response
+             .temporaryRedirect(info.getBaseUriBuilder().path("/web/bookstore/bookstream").build())
+             .entity(new StreamingOutput() {
+                 @Override
+                 public void write(OutputStream out) throws IOException {
+                     LockSupport.parkNanos(TimeUnit.MILLISECONDS.toNanos(500));
+                     out.write("Error while getting books".getBytes(StandardCharsets.UTF_8));
+                     out.flush();
+                 }
+             })
+             .build();
+    }
+
     @GET
     @Path("/bookstream")
     @Produces("application/xml")