SPNEGO TLS verification

Signed-off-by: Akira Ajisaka <aajisaka@apache.org>
(cherry picked from commit 81d8a887b0406380e469c76ed2e41022a6372dd7)

 Conflicts:
	hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/web/WebHdfsFileSystem.java

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/web/WebHdfsFileSystem.java

@@ -140,6 +140,7 @@ public class WebHdfsFileSystem extends FileSystem
       + "/v" + VERSION;
   public static final String EZ_HEADER = "X-Hadoop-Accept-EZ";
   public static final String FEFINFO_HEADER = "X-Hadoop-feInfo";
+  public static final String DFS_HTTP_POLICY_KEY = "dfs.http.policy";
 
   /**
    * Default connection factory may be overridden in tests to use smaller
@@ -169,6 +170,7 @@ public class WebHdfsFileSystem extends FileSystem
       new ObjectMapper().reader(Map.class);
 
   private DFSOpsCountStatistics storageStatistics;
+  private boolean isTLSKrb;
 
   /**
    * Return the protocol scheme for the FileSystem.
@@ -231,6 +233,8 @@ public class WebHdfsFileSystem extends FileSystem
           .newDefaultURLConnectionFactory(connectTimeout, readTimeout, conf);
     }
 
+    this.isTLSKrb = "HTTPS_ONLY".equals(conf.get(DFS_HTTP_POLICY_KEY));
+
     ugi = UserGroupInformation.getCurrentUser();
     this.uri = URI.create(uri.getScheme() + "://" + uri.getAuthority());
     this.nnAddrs = resolveNNAddr();
@@ -690,6 +694,11 @@ public class WebHdfsFileSystem extends FileSystem
       //redirect hostname and port
       redirectHost = null;
 
+      if (url.getProtocol().equals("http") &&
+        UserGroupInformation.isSecurityEnabled() &&
+        isTLSKrb) {
+        throw new IOException("Access denied: dfs.http.policy is HTTPS_ONLY.");
+      }
 
       // resolve redirects for a DN operation unless already resolved
       if (op.getRedirect() && !redirected) {