sshd: add support for ssh-agent

Add a simple SSH agent connector using JNA. Include com.sum.jna and
com.sun.jna.platform in the target platform.

JNA is used to communicate through Unix domain sockets with ssh-agent,
and if on Windows, to communicate via shared memory with Pageant.

The new bundle o.e.j.ssh.apache.agent is an OSGi fragment so that
the java.util.ServiceLoader can find the provided factory without
further ado in OSGi environments.

Adapt both maven and bazel builds to include the new bundle.

Manually tested on OS X, CentOS 7, and Win10 with Pageant 0.76. Tested
by installing JGit built from this change into freshly downloaded
Eclipse 2021-12 M1, and then doing git fetches via SSH with different
~/.ssh/config settings (explicit IdentityFile, without any but a key in
the agent, with no keys and a key in the agent and IdentitiesOnly=yes
(must fail)).

Bug: 541274
Bug: 541275
Change-Id: I34e85467293707dbad1eb44d1f40fc2e70ba3622
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

4 files changed, 29 insertions, 12 deletions

diff --git a/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/ApacheSshProtocol2Test.java b/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/ApacheSshProtocol2Test.java
index 0ad96b9acf..eef0402b07 100644
--- a/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/ApacheSshProtocol2Test.java
+++ b/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/ApacheSshProtocol2Test.java
@@ -26,12 +26,15 @@ public class ApacheSshProtocol2Test extends SshBasicTestBase {
 
 	@Override
 	protected SshSessionFactory createSessionFactory() {
-		SshdSessionFactory result = new SshdSessionFactory(new JGitKeyCache(),
-				null);
-		// The home directory is mocked at this point!
-		result.setHomeDirectory(FS.DETECTED.userHome());
-		result.setSshDirectory(sshDir);
-		return result;
+		return new SshdSessionFactoryBuilder()
+				// No proxies in tests
+				.setProxyDataFactory(null)
+				// No ssh-agent in tests
+				.setConnectorFactory(null)
+				// The home directory is mocked at this point!
+				.setHomeDirectory(FS.DETECTED.userHome())
+				.setSshDirectory(sshDir)
+				.build(new JGitKeyCache());
 	}
 
 	@Override
diff --git a/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/ApacheSshTest.java b/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/ApacheSshTest.java
index c1f5fef3cd..85626d8ee3 100644
--- a/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/ApacheSshTest.java
+++ b/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/ApacheSshTest.java
@@ -65,12 +65,15 @@ public class ApacheSshTest extends SshTestBase {
 
 	@Override
 	protected SshSessionFactory createSessionFactory() {
-		SshdSessionFactory result = new SshdSessionFactory(new JGitKeyCache(),
-				null);
-		// The home directory is mocked at this point!
-		result.setHomeDirectory(FS.DETECTED.userHome());
-		result.setSshDirectory(sshDir);
-		return result;
+		return new SshdSessionFactoryBuilder()
+				// No proxies in tests
+				.setProxyDataFactory(null)
+				// No ssh-agent in tests
+				.setConnectorFactory(null)
+				// The home directory is mocked at this point!
+				.setHomeDirectory(FS.DETECTED.userHome())
+				.setSshDirectory(sshDir)
+				.build(new JGitKeyCache());
 	}
 
 	@Override
diff --git a/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/NoFilesSshBuilderTest.java b/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/NoFilesSshBuilderTest.java
index 9d64adc95e..fd51e0cf47 100644
--- a/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/NoFilesSshBuilderTest.java
+++ b/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/NoFilesSshBuilderTest.java
@@ -50,6 +50,10 @@ public class NoFilesSshBuilderTest extends SshTestHarness {
 	@Override
 	protected SshSessionFactory createSessionFactory() {
 		return new SshdSessionFactoryBuilder() //
+				// No proxies in tests
+				.setProxyDataFactory(null)
+				// No ssh-agent in tests
+				.setConnectorFactory(null)
 				.setConfigStoreFactory((h, f, u) -> null)
 				.setDefaultKeysProvider(f -> new KeyAuthenticator())
 				.setServerKeyDatabase((h, s) -> new ServerKeyDatabase() {
diff --git a/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/NoFilesSshTest.java b/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/NoFilesSshTest.java
index 7b6e508c31..04c1c605d8 100644
--- a/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/NoFilesSshTest.java
+++ b/org.eclipse.jgit.ssh.apache.test/tst/org/eclipse/jgit/transport/sshd/NoFilesSshTest.java
@@ -33,6 +33,7 @@ import org.eclipse.jgit.junit.ssh.SshTestHarness;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.transport.CredentialsProvider;
 import org.eclipse.jgit.transport.SshSessionFactory;
+import org.eclipse.jgit.transport.sshd.agent.ConnectorFactory;
 import org.eclipse.jgit.util.FS;
 import org.junit.After;
 import org.junit.Test;
@@ -81,6 +82,12 @@ public class NoFilesSshTest extends SshTestHarness {
 			}
 
 			@Override
+			protected ConnectorFactory getConnectorFactory() {
+				// No ssh-agent in tests
+				return null;
+			}
+
+			@Override
 			protected Iterable<KeyPair> getDefaultKeys(File dir) {
 				// This would work for this simple test case:
 				// return Collections.singletonList(testUserKey);