HDFS-14242. OIV WebImageViewer: NPE when param op is not specified. Contributed by Siyao Meng.

Signed-off-by: Wei-Chiu Chuang <weichiu@apache.org>

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/FSImageHandler.java

@@ -85,10 +85,15 @@ class FSImageHandler extends SimpleChannelInboundHandler<HttpRequest> {
     }
 
     QueryStringDecoder decoder = new QueryStringDecoder(request.getUri());
+    // check path. throw exception if path doesn't start with WEBHDFS_PREFIX
+    String path = getPath(decoder);
     final String op = getOp(decoder);
+    // check null op
+    if (op == null) {
+      throw new IllegalArgumentException("Param op must be specified.");
+    }
 
     final String content;
-    String path = getPath(decoder);
     switch (op) {
     case "GETFILESTATUS":
       content = image.getFileStatus(path);

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/TestOfflineImageViewer.java

@@ -624,6 +624,25 @@ public class TestOfflineImageViewer {
     }
   }
 
+  @Test
+  public void testWebImageViewerNullOp() throws Exception {
+    WebImageViewer viewer = new WebImageViewer(
+        NetUtils.createSocketAddr("localhost:0"));
+    try {
+      viewer.initServer(originalFsimage.getAbsolutePath());
+      int port = viewer.getPort();
+
+      // null op
+      URL url = new URL("http://localhost:" + port +
+          "/webhdfs/v1/");
+      // should get HTTP_BAD_REQUEST. NPE gets HTTP_INTERNAL_ERROR
+      verifyHttpResponseCode(HttpURLConnection.HTTP_BAD_REQUEST, url);
+    } finally {
+      // shutdown the viewer
+      viewer.close();
+    }
+  }
+
   @Test
   public void testWebImageViewerSecureMode() throws Exception {
     Configuration conf = new Configuration();