Enhance DerValue::getOctetString to be able to read multi-level constructed value.

Author: wangweij

src/java.base/share/classes/sun/security/util/DerValue.java

@@ -505,7 +505,7 @@ public byte[] getOctetString() throws IOException {
             ByteArrayOutputStream bout = new ByteArrayOutputStream();
             DerInputStream dis = new DerInputStream(this);
             while (dis.available() > 0) {
-                bout.write(dis.getOctetString());
+                bout.write(dis.getDerValue().getOctetString());
             }
             return bout.toByteArray();
         }

test/jdk/sun/security/util/DerValue/DeepOctets.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8249783
+ * @summary read very deep constructed OCTET STRING
+ * @modules java.base/sun.security.util
+ * @library /test/lib
+ */
+
+import jdk.test.lib.Asserts;
+import jdk.test.lib.Utils;
+import sun.security.util.DerInputStream;
+import sun.security.util.DerValue;
+
+import java.io.IOException;
+
+public class DeepOctets {
+
+    public static void main(String[] args) throws Exception {
+        byte[] input = {
+            0x24, 24,
+                0x24, 8, 4, 2, 'a', 'b', 4, 2, 'c', 'd',
+                0x24, 8, 4, 2, 'e', 'f', 4, 2, 'g', 'h',
+                4, 2, 'i', 'j'
+        };
+
+        // DerValue::getOctetString supports constructed BER
+        byte[] s = new DerValue(input).getOctetString();
+        Asserts.assertEQ(new String(s), "abcdefghij");
+
+        // DerInputStream::getOctetString does not
+        Utils.runAndCheckException(
+                () -> new DerInputStream(input).getOctetString(),
+                IOException.class);
+    }
+}