--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.net.http/share/classes/jdk/internal/net/http/RedirectFilter.java	Tue Apr 17 08:54:17 2018 -0700
@@ -0,0 +1,137 @@
+/*
+ * Copyright (c) 2015, 2018, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+
+package jdk.internal.net.http;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpHeaders;
+import jdk.internal.net.http.common.Log;
+import jdk.internal.net.http.common.Utils;
+
+class RedirectFilter implements HeaderFilter {
+
+    HttpRequestImpl request;
+    HttpClientImpl client;
+    HttpClient.Redirect policy;
+    String method;
+    MultiExchange<?> exchange;
+    static final int DEFAULT_MAX_REDIRECTS = 5;
+    URI uri;
+
+    static final int max_redirects = Utils.getIntegerNetProperty(
+            "jdk.httpclient.redirects.retrylimit", DEFAULT_MAX_REDIRECTS
+    );
+
+    // A public no-arg constructor is required by FilterFactory
+    public RedirectFilter() {}
+
+    @Override
+    public synchronized void request(HttpRequestImpl r, MultiExchange<?> e) throws IOException {
+        this.request = r;
+        this.client = e.client();
+        this.policy = client.followRedirects();
+
+        this.method = r.method();
+        this.uri = r.uri();
+        this.exchange = e;
+    }
+
+    @Override
+    public synchronized HttpRequestImpl response(Response r) throws IOException {
+        return handleResponse(r);
+    }
+
+    private static String redirectedMethod(int statusCode, String orig) {
+        switch (statusCode) {
+            case 301:
+            case 302:
+                return orig.equals("POST") ? "GET" : orig;
+            case 303:
+                return "GET";
+            case 307:
+            case 308:
+                return orig;
+            default:
+                // unexpected but return orig
+                return orig;
+        }
+    }
+
+    /**
+     * Checks to see if a new request is needed and returns it.
+     * Null means response is ok to return to user.
+     */
+    private HttpRequestImpl handleResponse(Response r) {
+        int rcode = r.statusCode();
+        if (rcode == 200 || policy == HttpClient.Redirect.NEVER) {
+            return null;
+        }
+        if (rcode >= 300 && rcode <= 399) {
+            URI redir = getRedirectedURI(r.headers());
+            String newMethod = redirectedMethod(rcode, method);
+            Log.logTrace("response code: {0}, redirected URI: {1}", rcode, redir);
+            if (canRedirect(redir) && ++exchange.numberOfRedirects < max_redirects) {
+                Log.logTrace("redirect to: {0} with method: {1}", redir, newMethod);
+                return HttpRequestImpl.newInstanceForRedirection(redir, newMethod, request);
+            } else {
+                Log.logTrace("not redirecting");
+                return null;
+            }
+        }
+        return null;
+    }
+
+    private URI getRedirectedURI(HttpHeaders headers) {
+        URI redirectedURI;
+        redirectedURI = headers.firstValue("Location")
+                .map(URI::create)
+                .orElseThrow(() -> new UncheckedIOException(
+                        new IOException("Invalid redirection")));
+
+        // redirect could be relative to original URL, but if not
+        // then redirect is used.
+        redirectedURI = uri.resolve(redirectedURI);
+        return redirectedURI;
+    }
+
+    private boolean canRedirect(URI redir) {
+        String newScheme = redir.getScheme();
+        String oldScheme = uri.getScheme();
+        switch (policy) {
+            case ALWAYS:
+                return true;
+            case NEVER:
+                return false;
+            case NORMAL:
+                return newScheme.equalsIgnoreCase(oldScheme)
+                        || newScheme.equalsIgnoreCase("https");
+            default:
+                throw new InternalError();
+        }
+    }
+}