Builder API to configure SshdSessionFactories

A builder API provides a more convenient way to define a customized
SshdSessionFactory by hiding the subclassing.

Also provide a new interface SshConfigStore to abstract away the
specifics of reading a ssh config file, and provide a way to customize
the concrete ssh config implementation to be used. This facilitates
using an alternate ssh config implementation that may or may not be
based on files.

Change-Id: Ib9038e8ff2a4eb3a9ce7b3554d1450befec8e1e1
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

2 files changed, 124 insertions, 4 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/transport/ssh/OpenSshConfigFile.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/transport/ssh/OpenSshConfigFile.java
index 2fbc9122f1..98c63cdcdd 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/transport/ssh/OpenSshConfigFile.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/transport/ssh/OpenSshConfigFile.java
@@ -32,6 +32,7 @@ import java.util.TreeSet;
 import org.eclipse.jgit.annotations.NonNull;
 import org.eclipse.jgit.errors.InvalidPatternException;
 import org.eclipse.jgit.fnmatch.FileNameMatcher;
+import org.eclipse.jgit.transport.SshConfigStore;
 import org.eclipse.jgit.transport.SshConstants;
 import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.StringUtils;
@@ -80,7 +81,7 @@ import org.eclipse.jgit.util.SystemReader;
  * @see <a href="http://man.openbsd.org/OpenBSD-current/man5/ssh_config.5">man
  *      ssh-config</a>
  */
-public class OpenSshConfigFile {
+public class OpenSshConfigFile implements SshConfigStore {
 
 	/**
 	 * "Host" name of the HostEntry for the default options before the first
@@ -152,8 +153,9 @@ public class OpenSshConfigFile {
 	 *            the user supplied; <= 0 if none
 	 * @param userName
 	 *            the user supplied, may be {@code null} or empty if none given
-	 * @return r configuration for the requested name.
+	 * @return the configuration for the requested name.
 	 */
+	@Override
 	@NonNull
 	public HostEntry lookup(@NonNull String hostName, int port,
 			String userName) {
@@ -446,7 +448,7 @@ public class OpenSshConfigFile {
 	 * of several matching host entries, %-substitutions, and ~ replacement have
 	 * all been done.
 	 */
-	public static class HostEntry {
+	public static class HostEntry implements SshConfigStore.HostConfig {
 
 		/**
 		 * Keys that can be specified multiple times, building up a list. (I.e.,
@@ -489,7 +491,7 @@ public class OpenSshConfigFile {
 		private Map<String, List<String>> listOptions;
 
 		/**
-		 * Retrieves the value of a single-valued key, or the first is the key
+		 * Retrieves the value of a single-valued key, or the first if the key
 		 * has multiple values. Keys are case-insensitive, so
 		 * {@code getValue("HostName") == getValue("HOSTNAME")}.
 		 *
@@ -497,6 +499,7 @@ public class OpenSshConfigFile {
 		 *            to get the value of
 		 * @return the value, or {@code null} if none
 		 */
+		@Override
 		public String getValue(String key) {
 			String result = options != null ? options.get(key) : null;
 			if (result == null) {
@@ -524,6 +527,7 @@ public class OpenSshConfigFile {
 		 *            to get the values of
 		 * @return a possibly empty list of values
 		 */
+		@Override
 		public List<String> getValues(String key) {
 			List<String> values = listOptions != null ? listOptions.get(key)
 					: null;
@@ -778,6 +782,7 @@ public class OpenSshConfigFile {
 		 *
 		 * @return all single-valued options
 		 */
+		@Override
 		@NonNull
 		public Map<String, String> getOptions() {
 			if (options == null) {
@@ -792,6 +797,7 @@ public class OpenSshConfigFile {
 		 *
 		 * @return all multi-valued options
 		 */
+		@Override
 		@NonNull
 		public Map<String, List<String>> getMultiValuedOptions() {
 			if (listOptions == null && multiOptions == null) {
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/SshConfigStore.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/SshConfigStore.java
new file mode 100644
index 0000000000..04a4922bb9
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/SshConfigStore.java
@@ -0,0 +1,114 @@
+/*
+ * Copyright (C) 2020, Thomas Wolf <thomas.wolf@paranor.ch> and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Distribution License v. 1.0 which is available at
+ * https://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+package org.eclipse.jgit.transport;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+import org.eclipse.jgit.annotations.NonNull;
+
+/**
+ * An abstraction for a SSH config storage, like the OpenSSH ~/.ssh/config file.
+ *
+ * @since 5.8
+ */
+public interface SshConfigStore {
+
+	/**
+	 * Locate the configuration for a specific host request.
+	 *
+	 * @param hostName
+	 *            to look up
+	 * @param port
+	 *            the user supplied; <= 0 if none
+	 * @param userName
+	 *            the user supplied, may be {@code null} or empty if none given
+	 * @return the configuration for the requested name.
+	 */
+	@NonNull
+	HostConfig lookup(@NonNull String hostName, int port, String userName);
+
+	/**
+	 * A host entry from the ssh config. Any merging of global values and of
+	 * several matching host entries, %-substitutions, and ~ replacement have
+	 * all been done.
+	 */
+	interface HostConfig {
+
+		/**
+		 * Retrieves the value of a single-valued key, or the first if the key
+		 * has multiple values. Keys are case-insensitive, so
+		 * {@code getValue("HostName") == getValue("HOSTNAME")}.
+		 *
+		 * @param key
+		 *            to get the value of
+		 * @return the value, or {@code null} if none
+		 */
+		String getValue(String key);
+
+		/**
+		 * Retrieves the values of a multi- or list-valued key. Keys are
+		 * case-insensitive, so
+		 * {@code getValue("HostName") == getValue("HOSTNAME")}.
+		 *
+		 * @param key
+		 *            to get the values of
+		 * @return a possibly empty list of values
+		 */
+		List<String> getValues(String key);
+
+		/**
+		 * Retrieves an unmodifiable map of all single-valued options, with
+		 * case-insensitive lookup by keys.
+		 *
+		 * @return all single-valued options
+		 */
+		@NonNull
+		Map<String, String> getOptions();
+
+		/**
+		 * Retrieves an unmodifiable map of all multi- or list-valued options,
+		 * with case-insensitive lookup by keys.
+		 *
+		 * @return all multi-valued options
+		 */
+		@NonNull
+		Map<String, List<String>> getMultiValuedOptions();
+
+	}
+
+	/**
+	 * An empty {@link HostConfig}.
+	 */
+	static final HostConfig EMPTY_CONFIG = new HostConfig() {
+
+		@Override
+		public String getValue(String key) {
+			return null;
+		}
+
+		@Override
+		public List<String> getValues(String key) {
+			return Collections.emptyList();
+		}
+
+		@Override
+		public Map<String, String> getOptions() {
+			return Collections.emptyMap();
+		}
+
+		@Override
+		public Map<String, List<String>> getMultiValuedOptions() {
+			return Collections.emptyMap();
+		}
+
+	};
+}