Add a RefFilter interface to ReceivePack and UploadPack

When a user of ReceivePack or UploadPack wants to control what refs
are sent to the client, for instance when some refs should be hidden
from some clients, this interface can be extended to provide a fine
grained control over what refs are sent to the client.

Change-Id: Ie6320b0f8922e1a5e1bad91c016bd476ea094366

org.eclipse.jgit/src/org/eclipse/jgit/transport/ReceivePack.java

@@ -126,6 +126,9 @@ public class ReceivePack {
 	/** Identity to record action as within the reflog. */
 	private PersonIdent refLogIdent;
 
+	/** Filter used while advertising the refs to the client. */
+	private RefFilter refFilter;
+
 	/** Hook to validate the update commands before execution. */
 	private PreReceiveHook preReceive;
 
@@ -184,6 +187,7 @@ public class ReceivePack {
 		allowDeletes = cfg.allowDeletes;
 		allowNonFastForwards = cfg.allowNonFastForwards;
 		allowOfsDelta = cfg.allowOfsDelta;
+		refFilter = RefFilter.DEFAULT;
 		preReceive = PreReceiveHook.NULL;
 		postReceive = PostReceiveHook.NULL;
 	}
@@ -335,6 +339,26 @@ public class ReceivePack {
 		refLogIdent = pi;
 	}
 
+	/** @return the filter used while advertising the refs to the client */
+	public RefFilter getRefFilter() {
+		return refFilter;
+	}
+
+	/**
+	 * Set the filter used while advertising the refs to the client.
+	 * <p>
+	 * Only refs allowed by this filter will be shown to the client.
+	 * Clients may still attempt to create or update a reference hidden
+	 * by the configured {@link RefFilter}. These attempts should be
+	 * rejected by a matching {@link PreReceiveHook}.
+	 *
+	 * @param refFilter
+	 *            the filter; may be null to show all refs.
+	 */
+	public void setRefFilter(final RefFilter refFilter) {
+		this.refFilter = refFilter != null ? refFilter : RefFilter.DEFAULT;
+	}
+
 	/** @return get the hook invoked before updates occur. */
 	public PreReceiveHook getPreReceiveHook() {
 		return preReceive;
@@ -521,7 +545,7 @@ public class ReceivePack {
 		if (biDirectionalPipe)
 			sendAdvertisedRefs(new PacketLineOutRefAdvertiser(pckOut));
 		else
-			refs = db.getAllRefs();
+			refs = refFilter.filter(db.getAllRefs());
 		recvCommands();
 		if (!commands.isEmpty()) {
 			enableCapabilities();
@@ -589,7 +613,7 @@ public class ReceivePack {
 		adv.advertiseCapability(CAPABILITY_REPORT_STATUS);
 		if (allowOfsDelta)
 			adv.advertiseCapability(CAPABILITY_OFS_DELTA);
-		refs = db.getAllRefs();
+		refs = refFilter.filter(db.getAllRefs());
 		final Ref head = refs.remove(Constants.HEAD);
 		adv.send(refs);
 		if (head != null && !head.isSymbolic())

org.eclipse.jgit/src/org/eclipse/jgit/transport/RefFilter.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2010, Google Inc.
+ * 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.transport;
+
+import java.util.Map;
+
+import org.eclipse.jgit.lib.Ref;
+
+/**
+ * Filters the list of refs that are advertised to the client.
+ * <p>
+ * The filter is called by {@link ReceivePack} and {@link UploadPack} to ensure
+ * that the refs are filtered before they are advertised to the client.
+ * <p>
+ * This can be used by applications to control visibility of certain refs based
+ * on a custom set of rules.
+ */
+public interface RefFilter {
+	/** The default filter, allows all refs to be shown. */
+	public static final RefFilter DEFAULT = new RefFilter() {
+		public Map<String, Ref> filter (final Map<String, Ref> refs) {
+			return refs;
+		}
+	};
+
+	/**
+	 * Filters a {@code Map} of refs before it is advertised to the client.
+	 *
+	 * @param refs
+	 *            the refs which this method need to consider.
+	 * @return
+	 *            the filtered map of refs.
+	 */
+	public Map<String, Ref> filter(Map<String, Ref> refs);
+}

org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java

@@ -131,6 +131,9 @@ public class UploadPack {
 	/** The refs we advertised as existing at the start of the connection. */
 	private Map<String, Ref> refs;
 
+	/** Filter used while advertising the refs to the client. */
+	private RefFilter refFilter;
+
 	/** Capabilities requested by the client. */
 	private final Set<String> options = new HashSet<String>();
 
@@ -183,9 +186,10 @@ public class UploadPack {
 		SAVE.add(ADVERTISED);
 		SAVE.add(WANT);
 		SAVE.add(PEER_HAS);
+		refFilter = RefFilter.DEFAULT;
 	}
 
-	/** @return the repository this receive completes into. */
+	/** @return the repository this upload is reading from. */
 	public final Repository getRepository() {
 		return db;
 	}
@@ -233,6 +237,26 @@ public class UploadPack {
 		biDirectionalPipe = twoWay;
 	}
 
+	/** @return the filter used while advertising the refs to the client */
+	public RefFilter getRefFilter() {
+		return refFilter;
+	}
+
+	/**
+	 * Set the filter used while advertising the refs to the client.
+	 * <p>
+	 * Only refs allowed by this filter will be sent to the client. This can
+	 * be used by a server to restrict the list of references the client can
+	 * obtain through clone or fetch, effectively limiting the access to only
+	 * certain refs.
+	 *
+	 * @param refFilter
+	 *            the filter; may be null to show all refs.
+	 */
+	public void setRefFilter(final RefFilter refFilter) {
+		this.refFilter = refFilter != null ? refFilter : RefFilter.DEFAULT;
+	}
+
 	/**
 	 * Execute the upload task on the socket.
 	 *
@@ -285,7 +309,7 @@ public class UploadPack {
 		if (biDirectionalPipe)
 			sendAdvertisedRefs(new PacketLineOutRefAdvertiser(pckOut));
 		else {
-			refs = db.getAllRefs();
+			refs = refFilter.filter(db.getAllRefs());
 			for (Ref r : refs.values()) {
 				try {
 					walk.parseAny(r.getObjectId()).add(ADVERTISED);
@@ -329,7 +353,7 @@ public class UploadPack {
 		adv.advertiseCapability(OPTION_THIN_PACK);
 		adv.advertiseCapability(OPTION_NO_PROGRESS);
 		adv.setDerefTags(true);
-		refs = db.getAllRefs();
+		refs = refFilter.filter(db.getAllRefs());
 		adv.send(refs);
 		adv.end();
 	}