Adds GSSManager factory class, to be used for SPNEGO HTTP authentication

Adds a factory class for GSSManager. GSSManager is already a factory class but
it doesn't work well with SPNEGO HTTP authentication unless the
javax.security.auth.useSubjectCredsOnly system property is set to false.

On Sun JDK, Sun GSSManagerImpl can be configured directly for SPNEGO auth
(without setting any system property). For a better experience, the class
availability is detected by reflection and used instead.

Detection is only done once, and fallbacks to org.ietf.jgss.GSSManager.

Bug: 428836
Change-Id: Idb9123d1f4013966919db43043ec959d4b133ae2
Signed-off-by: Laurent Goujon <lgoujon@twitter.com>
Signed-off-by: Chris Aniszczyk <caniszczyk@gmail.com>

org.eclipse.jgit/src/org/eclipse/jgit/util/GSSManagerFactory.java

@@ -0,0 +1,158 @@
+/*
+ * Copyright (C) 2014 Laurent Goujon <lgoujon@twitter.com>
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package org.eclipse.jgit.util;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.net.URL;
+
+import org.ietf.jgss.GSSManager;
+
+/**
+ * Factory to detect which GSSManager implementation should be used.
+ *
+ */
+public abstract class GSSManagerFactory {
+	/**
+	 * Auto-detects the GSSManager factory to use based on system.
+	 *
+	 * @return detected GSSManager factory
+	 */
+	public static GSSManagerFactory detect() {
+		return (SunGSSManagerFactory.isSupported()) ? new SunGSSManagerFactory()
+				: new DefaultGSSManagerFactory();
+	}
+
+	/**
+	 * Returns a GSS Manager instance for the provided url
+	 *
+	 * @param url
+	 *            the repository url
+	 * @return a GSSManager instance
+	 */
+	public abstract GSSManager newInstance(URL url);
+
+	/**
+	 * DefaultGSSManagerFactory uses @link {@link GSSManager#getInstance()} but
+	 * you might need to set
+	 * <code>javax.security.auth.useSubjectCredsOnly</code> system property to
+	 * <code>false</code> for authentication to work.
+	 */
+	private static class DefaultGSSManagerFactory extends GSSManagerFactory {
+		private static final GSSManager INSTANCE = GSSManager.getInstance();
+
+		@Override
+		public GSSManager newInstance(URL url) {
+			return INSTANCE;
+		}
+	}
+
+	private static class SunGSSManagerFactory extends GSSManagerFactory {
+		private static boolean IS_SUPPORTED;
+		private static Constructor<?> HTTP_CALLER_INFO_CONSTRUCTOR;
+		private static Constructor<?> HTTP_CALLER_CONSTRUCTOR;
+
+		private static Constructor<?> GSS_MANAGER_IMPL_CONSTRUCTOR;
+
+		static {
+			try {
+				init();
+				IS_SUPPORTED = true;
+			} catch (Exception e) {
+				IS_SUPPORTED = false;
+			}
+		}
+
+		private static void init() throws ClassNotFoundException,
+				NoSuchMethodException {
+			Class<?> httpCallerInfoClazz = Class
+					.forName("sun.net.www.protocol.http.HttpCallerInfo"); //$NON-NLS-1$
+			HTTP_CALLER_INFO_CONSTRUCTOR = httpCallerInfoClazz
+					.getConstructor(URL.class);
+
+			Class<?> httpCallerClazz = Class
+					.forName("sun.security.jgss.HttpCaller"); //$NON-NLS-1$
+			HTTP_CALLER_CONSTRUCTOR = httpCallerClazz
+					.getConstructor(httpCallerInfoClazz);
+
+			Class<?> gssCallerClazz = Class
+					.forName("sun.security.jgss.GSSCaller"); //$NON-NLS-1$
+			Class<?> gssManagerImplClazz = Class
+					.forName("sun.security.jgss.GSSManagerImpl"); //$NON-NLS-1$
+			GSS_MANAGER_IMPL_CONSTRUCTOR = gssManagerImplClazz
+					.getConstructor(gssCallerClazz);
+
+		}
+
+		/**
+		 * Detects if SunGSSManagerProvider is supported by the system
+		 *
+		 * @return true if it is supported
+		 */
+		public static boolean isSupported() {
+			return IS_SUPPORTED;
+		}
+
+		@Override
+		public GSSManager newInstance(URL url) {
+			try {
+				Object httpCallerInfo = HTTP_CALLER_INFO_CONSTRUCTOR
+						.newInstance(url);
+				Object httpCaller = HTTP_CALLER_CONSTRUCTOR
+						.newInstance(httpCallerInfo);
+
+				return (GSSManager) GSS_MANAGER_IMPL_CONSTRUCTOR
+						.newInstance(httpCaller);
+			} catch (InstantiationException e) {
+				throw new Error(e);
+			} catch (IllegalAccessException e) {
+				throw new Error(e);
+			} catch (IllegalArgumentException e) {
+				throw new Error(e);
+			} catch (InvocationTargetException e) {
+				throw new Error(e);
+			}
+		}
+	}
+}