[proxy] Fix proxy to be able to re-send request body (#5361)

Fixes #5360

This adds a small cache of the request body to ensure that it can be
re-sent.

TODO: still needs tested
(cherry picked from commit 978efaf1)

pulsar-proxy/src/main/java/org/apache/pulsar/proxy/server/AdminProxyHandler.java

@@ -20,9 +20,14 @@ package org.apache.pulsar.proxy.server;
 
 import static org.apache.commons.lang3.StringUtils.isBlank;
 
+import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.net.URI;
+import java.nio.ByteBuffer;
 import java.security.cert.X509Certificate;
+import java.util.Collections;
+import java.util.Iterator;
 import java.util.Objects;
 import java.util.concurrent.Executor;
 
@@ -30,6 +35,7 @@ import javax.net.ssl.SSLContext;
 import javax.servlet.ServletConfig;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
 
 import org.apache.pulsar.broker.web.AuthenticationFilter;
 import org.apache.pulsar.client.api.Authentication;
@@ -42,6 +48,7 @@ import org.eclipse.jetty.client.HttpClient;
 import org.eclipse.jetty.client.HttpRequest;
 import org.eclipse.jetty.client.ProtocolHandlers;
 import org.eclipse.jetty.client.RedirectProtocolHandler;
+import org.eclipse.jetty.client.api.ContentProvider;
 import org.eclipse.jetty.client.api.Request;
 import org.eclipse.jetty.http.HttpHeader;
 import org.eclipse.jetty.proxy.ProxyServlet;
@@ -133,6 +140,33 @@ class AdminProxyHandler extends ProxyServlet {
     }
 
 
+    // This class allows the request body to be replayed, the default implementation
+    // does not
+    protected class ReplayableProxyContentProvider extends ProxyInputStreamContentProvider {
+        private Boolean firstIteratorCalled = false;
+        private final ByteArrayOutputStream bodyBuffer;
+        protected ReplayableProxyContentProvider(HttpServletRequest request, HttpServletResponse response, Request proxyRequest, InputStream input) {
+            super(request, response, proxyRequest, input);
+            bodyBuffer = new ByteArrayOutputStream(request.getContentLength());
+        }
+
+        @Override
+        public Iterator<ByteBuffer> iterator() {
+            if (firstIteratorCalled) {
+                return Collections.singleton(ByteBuffer.wrap(bodyBuffer.toByteArray())).iterator();
+            } else {
+                firstIteratorCalled = true;
+                return super.iterator();
+            }
+        }
+
+        @Override
+        protected ByteBuffer onRead(byte[] buffer, int offset, int length) {
+            bodyBuffer.write(buffer, offset, length);
+            return super.onRead(buffer, offset, length);
+        }
+    }
+
     private static class JettyHttpClient extends HttpClient {
         public JettyHttpClient() {
             super();
@@ -159,6 +193,12 @@ class AdminProxyHandler extends ProxyServlet {
 
     }
 
+    @Override
+    protected ContentProvider proxyRequestContent(HttpServletRequest request,
+                                                  HttpServletResponse response, Request proxyRequest) throws IOException {
+        return new ReplayableProxyContentProvider(request, response, proxyRequest, request.getInputStream());
+    }
+
     @Override
     protected HttpClient newHttpClient() {
         try {

tests/integration/src/test/java/org/apache/pulsar/tests/integration/proxy/TestProxy.java

@@ -25,6 +25,7 @@ import java.util.Collections;
 import lombok.Cleanup;
 
 import org.apache.pulsar.client.admin.PulsarAdmin;
+import org.apache.pulsar.client.api.MessageId;
 import org.apache.pulsar.client.api.Producer;
 import org.apache.pulsar.client.api.PulsarClient;
 import org.apache.pulsar.client.api.Schema;
@@ -55,6 +56,7 @@ public class TestProxy extends PulsarTestSuite {
             .withEnv("clusterName", clusterName);
 
         specBuilder.externalService("proxy-via-url", proxyViaURL);
+
         return super.beforeSetupCluster(clusterName, specBuilder);
     }
 
@@ -108,4 +110,26 @@ public class TestProxy extends PulsarTestSuite {
         testProxy(proxyViaURL.getPlainTextServiceUrl(), proxyViaURL.getHttpServiceUrl());
     }
 
+    @Test
+    public void testProxyRequestBodyRedirect() throws Exception {
+        // See GH issue #5360, this ensures that we properly get a request with a body to be processed
+        final String tenant = "proxy-test-" + randomName(10);
+        final String namespace = tenant + "/ns1";
+        final String topic = "persistent://" + namespace + "/topic1";
+
+        @Cleanup
+        PulsarAdmin admin = PulsarAdmin.builder()
+                .serviceHttpUrl(pulsarCluster.getPlainTextServiceUrl())
+                .build();
+
+        admin.tenants().createTenant(tenant,
+                new TenantInfo(Collections.emptySet(), Collections.singleton(pulsarCluster.getClusterName())));
+
+        admin.namespaces().createNamespace(namespace, Collections.singleton(pulsarCluster.getClusterName()));
+
+        for (int i = 0; i < 10; i++) {
+            // Ensure we the command works even if re-directs happen with a request body
+            admin.topics().createSubscription(topic, "test-" + i, MessageId.earliest);
+        }
+    }
 }