8241389: URLConnection::getHeaderFields returns result inconsistent with getHeaderField/Key for FileURLConnection, FtpURLConnection

Reviewed-by: dfuchs

src/java.base/share/classes/sun/net/www/URLConnection.java

@@ -25,6 +25,7 @@
 
 package sun.net.www;
 
+import java.io.IOException;
 import java.net.URL;
 import java.util.*;
 
@@ -109,6 +110,26 @@ public abstract class URLConnection extends java.net.URLConnection {
         return properties == null ? null : properties.findValue(name);
     }
 
+
+    Map<String, List<String>> headerFields;
+
+    @Override
+    public Map<String, List<String>> getHeaderFields() {
+        if (headerFields == null) {
+            try {
+                getInputStream();
+                if (properties == null) {
+                    headerFields = super.getHeaderFields();
+                } else {
+                    headerFields = properties.getHeaders();
+                }
+            } catch (IOException e) {
+                return super.getHeaderFields();
+            }
+        }
+        return headerFields;
+    }
+
     /**
      * Return the key for the nth header field. Returns null if
      * there are fewer than n fields.  This can be used to iterate

src/java.base/share/classes/sun/net/www/protocol/file/FileURLConnection.java

@@ -138,6 +138,11 @@ public class FileURLConnection extends URLConnection {
         }
     }
 
+    public Map<String,List<String>> getHeaderFields() {
+        initializeHeaders();
+        return super.getHeaderFields();
+    }
+
     public String getHeaderField(String name) {
         initializeHeaders();
         return super.getHeaderField(name);

test/jdk/sun/net/www/protocol/file/GetHeaderFields.java

@@ -0,0 +1,101 @@
+/*
+ * 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 8241389
+ * @summary URLConnection::getHeaderFields returns result inconsistent with getHeaderField/Key for FileURLConnection, FtpURLConnection
+ */
+
+import java.net.*;
+import java.io.*;
+import java.util.*;
+
+public class GetHeaderFields {
+
+    public static void main(String[] args) {
+        HashMap<String,List<String>> map1 = new HashMap<>();
+        Map<String,List<String>> headers = null;
+
+        try {
+            File f = File.createTempFile("test", null);
+            f.deleteOnExit();
+            String s = f.getAbsolutePath();
+            s = s.startsWith("/") ? s : "/" + s;
+            URL url = new URL("file://localhost"+s);
+            URLConnection urlc = url.openConnection();
+            InputStream in = urlc.getInputStream();
+            headers = urlc.getHeaderFields();
+            Set<String> keys = headers.keySet();
+
+            int i = 0;
+            while (true) {
+                String key = urlc.getHeaderFieldKey(i);
+                if (key == null)
+                    break;
+                String val = urlc.getHeaderField(i);
+                putValue(map1,key,val);
+                i++;
+            }
+            System.out.println("headers = " + headers.toString());
+            System.out.println("map1 = " + map1.toString());
+            in.close();
+        } catch (java.io.FileNotFoundException fnfe) {
+            throw new RuntimeException("failed to recognize localhost");
+        } catch (Exception ex) {
+            throw new RuntimeException("Unexpected exception: " + ex);
+        }
+        if (!map1.equals(headers)) {
+            throw new RuntimeException("headers != map1");
+        }
+
+        // check connection to non-existent resource returns
+        // an empty map
+
+        URLConnection urlc = null;
+
+        try {
+            URL url = new URL("file:///dev/non/existing/ABCD/123/foobar/sqisjjlk");
+            urlc = url.openConnection();
+            urlc.getInputStream();
+        } catch (IOException e) {}
+
+        headers = urlc.getHeaderFields();
+        if (headers == null) {
+            throw new RuntimeException("expected empty map");
+        }
+        if (!headers.isEmpty()) {
+            throw new RuntimeException("expected empty map");
+        }
+
+    }
+
+    static void putValue(HashMap<String,List<String>> map, String key, String val) {
+        List<String> l = map.get(key);
+        if (l == null) {
+            l = new LinkedList<String>();
+            map.put(key, l);
+        }
+        l.add(val);
+    }
+}