From: Markus Koschany <apo@debian.org>
Date: Sun, 1 Nov 2015 17:54:39 +0100
Subject: ALPN

Provide the ALPN API with the undertow source package.

Forwarded: not-needed
---
 .../src/main/java/org/eclipse/jetty/alpn/ALPN.java | 252 +++++++++++++++++++++
 1 file changed, 252 insertions(+)
 create mode 100644 core/src/main/java/org/eclipse/jetty/alpn/ALPN.java

diff --git a/core/src/main/java/org/eclipse/jetty/alpn/ALPN.java b/core/src/main/java/org/eclipse/jetty/alpn/ALPN.java
new file mode 100644
index 0000000..6a70617
--- /dev/null
+++ b/core/src/main/java/org/eclipse/jetty/alpn/ALPN.java
@@ -0,0 +1,252 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.alpn;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import javax.net.ssl.SSLEngine;
+import javax.net.ssl.SSLSocket;
+
+/**
+ * {@link ALPN} provides an API to applications that want to make use of the
+ * <a href="http://tools.ietf.org/html/draft-ietf-tls-applayerprotoneg">Application Layer Protocol Negotiation</a>.
+ * <p/>
+ * The ALPN extension is only available when using the TLS protocol, therefore applications must
+ * ensure that the TLS protocol is used:
+ * <pre>
+ * SSLContext context = SSLContext.getInstance("TLSv1");
+ * </pre>
+ * Refer to the
+ * <a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#SSLContext">list
+ * of standard SSLContext protocol names</a> for further information on TLS protocol versions supported.
+ * <p/>
+ * Applications must register instances of either {@link SSLSocket} or {@link SSLEngine} with a
+ * {@link ClientProvider} or with a {@link ServerProvider}, depending whether they are on client or
+ * server side.
+ * <p/>
+ * The ALPN implementation will invoke the provider callbacks to allow applications to interact
+ * with the negotiation of the protocol.
+ * <p/>
+ * Client side typical usage:
+ * <pre>
+ * SSLSocket sslSocket = ...;
+ * ALPN.put(sslSocket, new ALPN.ClientProvider()
+ * {
+ *     &#64;Override
+ *     public boolean supports()
+ *     {
+ *         return true;
+ *     }
+ *
+ *     &#64;Override
+ *     public List&lt;String&gt; protocols()
+ *     {
+ *         return Arrays.asList("spdy/3", "http/1.1");
+ *     }
+ *
+ *     &#64;Override
+ *     public void unsupported()
+ *     {
+ *     }
+ *
+ *     &#64;Override
+ *     public void selected(String protocol)
+ *     {
+ *         System.out.println("Selected protocol: " + protocol);
+ *     }
+ *  });
+ * </pre>
+ * Server side typical usage:
+ * <pre>
+ * SSLSocket sslSocket = ...;
+ * ALPN.put(sslSocket, new ALPN.ServerProvider()
+ * {
+ *     &#64;Override
+ *     public void unsupported()
+ *     {
+ *     }
+ *
+ *     &#64;Override
+ *     public String select(List&lt;String&gt; protocols)
+ *     {
+ *         return protocols.get(0);
+ *     }
+ *  });
+ * </pre>
+ * Applications must ensure to deregister {@link SSLSocket} or {@link SSLEngine} instances,
+ * because they are kept in a global map.
+ * Deregistration should typically happen when the application detects the end of the protocol
+ * negotiation, and/or when the associated socket connection is closed.
+ * <p/>
+ * In order to help application development, you can set the {@link ALPN#debug} field
+ * to {@code true} to have debug code printed to {@link System#err}.
+ */
+public class ALPN
+{
+    /**
+     * Flag that enables printing of debug statements to {@link System#err}.
+     */
+    public static boolean debug = false;
+
+    private static Map<Object, Provider> objects = Collections.synchronizedMap(new HashMap<Object, Provider>());
+
+    private ALPN()
+    {
+    }
+
+    /**
+     * Registers a SSLSocket with a provider.
+     *
+     * @param socket   the socket to register with the provider
+     * @param provider the provider to register with the socket
+     * @see #remove(SSLSocket)
+     */
+    public static void put(SSLSocket socket, Provider provider)
+    {
+        objects.put(socket, provider);
+    }
+
+    /**
+     * @param socket a socket registered with {@link #put(SSLSocket, Provider)}
+     * @return the provider registered with the given socket
+     */
+    public static Provider get(SSLSocket socket)
+    {
+        return objects.get(socket);
+    }
+
+    /**
+     * Unregisters the given SSLSocket.
+     *
+     * @param socket the socket to unregister
+     * @return the provider registered with the socket
+     * @see #put(SSLSocket, Provider)
+     */
+    public static Provider remove(SSLSocket socket)
+    {
+        return objects.remove(socket);
+    }
+
+    /**
+     * Registers a SSLEngine with a provider.
+     *
+     * @param engine   the engine to register with the provider
+     * @param provider the provider to register with the engine
+     * @see #remove(SSLEngine)
+     */
+    public static void put(SSLEngine engine, Provider provider)
+    {
+        objects.put(engine, provider);
+    }
+
+    /**
+     * @param engine an engine registered with {@link #put(SSLEngine, Provider)}
+     * @return the provider registered with the given engine
+     */
+    public static Provider get(SSLEngine engine)
+    {
+        return objects.get(engine);
+    }
+
+    /**
+     * Unregisters the given SSLEngine.
+     *
+     * @param engine the engine to unregister
+     * @return the provider registered with the engine
+     * @see #put(SSLEngine, Provider)
+     */
+    public static Provider remove(SSLEngine engine)
+    {
+        return objects.remove(engine);
+    }
+
+    /**
+     * Base, empty, interface for providers.
+     */
+    public interface Provider
+    {
+    }
+
+    /**
+     * The client-side provider interface that applications must
+     * implement to interact with the negotiation of the protocol.
+     */
+    public interface ClientProvider extends Provider
+    {
+        /**
+         * Callback invoked to let the implementation know whether an
+         * ALPN extension should be added to a ClientHello TLS message.
+         *
+         * @return true to add the ALPN extension, false otherwise
+         */
+        public boolean supports();
+
+        /**
+         * Callback invoked to let the implementation know the list
+         * of protocols that should be added to the ALPN extension in
+         * a ClientHello TLS message.
+         * <p/>
+         * This callback is invoked only if the {@link #supports()}
+         * returned true.
+         *
+         * @return the list of protocols supported by the client;
+         * if null or empty, the ALPN extension is not sent
+         */
+        public List<String> protocols();
+
+        /**
+         * Callback invoked to let the client application know that
+         * the server does not support ALPN.
+         */
+        public void unsupported();
+
+        /**
+         * Callback invoked to let the client application know
+         * the protocol chosen by the server.
+         *
+         * @param protocol the protocol selected by the server
+         */
+        public void selected(String protocol);
+    }
+
+    /**
+     * The server-side provider interface that applications must
+     * implement to interact with the negotiation of the protocol.
+     */
+    public interface ServerProvider extends Provider
+    {
+        /**
+         * Callback invoked to let the server application know that
+         * the client does not support ALPN.
+         */
+        public void unsupported();
+
+        /**
+         * Callback invoked to let the server application select
+         * a protocol among the ones sent by the client.
+         *
+         * @param protocols the protocols sent by the client
+         * @return the protocol selected by the server application;
+         * must not be null
+         */
+        public String select(List<String> protocols);
+    }
+}