Fix "direct buffer access" issue for Plugin SDK (#2511)

* Add test for direct buffer in request

* Safely access request byte buffer

* Fix formatting

---------

Co-authored-by: Naman Nandan <namankt55@gmail.com>

Author: marrodion

frontend/server/src/main/java/org/pytorch/serve/servingsdk/impl/ModelServerRequest.java

@@ -8,6 +8,7 @@
 import java.util.List;
 import java.util.Map;
 import org.pytorch.serve.servingsdk.http.Request;
+import org.pytorch.serve.util.NettyUtils;
 
 public class ModelServerRequest implements Request {
     private FullHttpRequest req;
@@ -45,6 +46,6 @@ public String getContentType() {
 
     @Override
     public ByteArrayInputStream getInputStream() {
-        return new ByteArrayInputStream(req.content().array());
+        return new ByteArrayInputStream(NettyUtils.getBytes(req.content()));
     }
 }

frontend/server/src/test/java/org/pytorch/serve/util/PluginSdkTest.java

@@ -0,0 +1,26 @@
+package org.pytorch.serve.util;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
+import io.netty.handler.codec.http.*;
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import org.pytorch.serve.servingsdk.http.Request;
+import org.pytorch.serve.servingsdk.impl.ModelServerRequest;
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+public class PluginSdkTest {
+    @Test
+    public void testReadRequestBodyFromPlugin() throws IOException {
+        ByteBuf buf = Unpooled.directBuffer();
+        buf.writeBytes("test".getBytes());
+        FullHttpRequest req =
+                new DefaultFullHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.POST, "", buf);
+        Request request = new ModelServerRequest(req, new QueryStringDecoder(""));
+        String line =
+                new BufferedReader(new InputStreamReader(request.getInputStream())).readLine();
+        Assert.assertEquals(line, "test");
+    }
+}

frontend/server/testng.xml

@@ -5,6 +5,7 @@
     <classes>
       <class name="org.pytorch.serve.util.ConfigManagerTest"/>
       <class name="org.pytorch.serve.util.ConnectorTest"/>
+      <class name="org.pytorch.serve.util.PluginSdkTest"/>
       <class name="org.pytorch.serve.CoverageTest"/>
       <class name="org.pytorch.serve.ModelServerTest"/>
       <class name="org.pytorch.serve.SnapshotTest"/>