sshd: Connector for the Win32-OpenSSH SSH agent

Win32-OpenSSH uses a named Windows pipe for communication. Implement
a connector for this mechanism using JNA. Choose the appropriate
connector based on the setting of the 'identityAgent' parameter.

Bug: 577053
Change-Id: I205f07fb33654aa18ca5db92706e65544ce38641
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

org.eclipse.jgit.ssh.apache.agent/resources/org/eclipse/jgit/internal/transport/sshd/agent/connector/Texts.properties

@@ -2,9 +2,11 @@ errCloseMappedFile=Cannot close mapped file: {0} - {1}
 errLastError=System message for error {0} could not be retrieved, got {1}
 errReleaseSharedMemory=Cannot release shared memory: {0} - {1}
 errUnknown=unknown error
+errUnknownIdentityAgent=IdentityAgent ''{0}'' unknown
 logErrorLoadLibrary=Cannot load socket library; SSH agent support is switched off
 msgCloseFailed=Cannot close SSH agent socket {0}
 msgConnectFailed=Could not connect to SSH agent via socket ''{0}''
+msgConnectPipeFailed=Could not connect to SSH agent via pipe ''{0}''
 msgNoMappedFile=Could not create file mapping: {0} - {1}
 msgNoSharedMemory=Could not initialize shared memory: {0} - {1}
 msgPageantUnavailable=Could not connect to Pageant
@@ -15,3 +17,4 @@ msgSharedMemoryFailed=Could not set up shared memory for communicating with Page
 msgShortRead=Short read from SSH agent, expected {0} bytes, got {1} bytes; last read() returned {2}
 pageant=Pageant
 unixDefaultAgent=ssh-agent
+winOpenSsh=Win32 OpenSSH

org.eclipse.jgit.ssh.apache.agent/src/org/eclipse/jgit/internal/transport/sshd/agent/connector/Factory.java

@@ -11,11 +11,15 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.text.MessageFormat;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.List;
+import java.util.Locale;
 
 import org.eclipse.jgit.transport.sshd.agent.Connector;
 import org.eclipse.jgit.transport.sshd.agent.ConnectorFactory;
+import org.eclipse.jgit.util.StringUtils;
 import org.eclipse.jgit.util.SystemReader;
 
 /**
@@ -29,7 +33,20 @@ public class Factory implements ConnectorFactory {
 	public Connector create(String identityAgent, File homeDir)
 			throws IOException {
 		if (SystemReader.getInstance().isWindows()) {
-			return new PageantConnector();
+			if (StringUtils.isEmptyOrNull(identityAgent)) {
+				// Default.
+				return new PageantConnector();
+			}
+			String winPath = identityAgent.replace('/', '\\');
+			if (PageantConnector.DESCRIPTOR.getIdentityAgent()
+					.equalsIgnoreCase(winPath)) {
+				return new PageantConnector();
+			}
+			if (winPath.toLowerCase(Locale.ROOT).startsWith("\\\\.\\pipe\\")) { //$NON-NLS-1$
+				return new WinPipeConnector(winPath);
+			}
+			throw new IOException(MessageFormat.format(
+					Texts.get().errUnknownIdentityAgent, identityAgent));
 		}
 		return new UnixDomainSocketConnector(identityAgent);
 	}
@@ -55,7 +72,11 @@ public String getName() {
 	 */
 	@Override
 	public Collection<ConnectorDescriptor> getSupportedConnectors() {
-		return Collections.singleton(getDefaultConnector());
+		if (SystemReader.getInstance().isWindows()) {
+			return List.of(PageantConnector.DESCRIPTOR,
+					WinPipeConnector.DESCRIPTOR);
+		}
+		return Collections.singleton(UnixDomainSocketConnector.DESCRIPTOR);
 	}
 
 	@Override

org.eclipse.jgit.ssh.apache.agent/src/org/eclipse/jgit/internal/transport/sshd/agent/connector/LibraryHolder.java

@@ -53,6 +53,10 @@ private LibraryHolder() {
 		kernel = Kernel32.INSTANCE;
 	}
 
+	String systemError() {
+		return systemError("[{0}] - {1}"); //$NON-NLS-1$
+	}
+
 	String systemError(String pattern) {
 		int lastError = kernel.GetLastError();
 		String msg;

org.eclipse.jgit.ssh.apache.agent/src/org/eclipse/jgit/internal/transport/sshd/agent/connector/Texts.java

@@ -31,9 +31,11 @@ public static Texts get() {
 	/***/ public String errLastError;
 	/***/ public String errReleaseSharedMemory;
 	/***/ public String errUnknown;
+	/***/ public String errUnknownIdentityAgent;
 	/***/ public String logErrorLoadLibrary;
 	/***/ public String msgCloseFailed;
 	/***/ public String msgConnectFailed;
+	/***/ public String msgConnectPipeFailed;
 	/***/ public String msgNoMappedFile;
 	/***/ public String msgNoSharedMemory;
 	/***/ public String msgPageantUnavailable;
@@ -44,5 +46,6 @@ public static Texts get() {
 	/***/ public String msgShortRead;
 	/***/ public String pageant;
 	/***/ public String unixDefaultAgent;
+	/***/ public String winOpenSsh;
 
 }

org.eclipse.jgit.ssh.apache.agent/src/org/eclipse/jgit/internal/transport/sshd/agent/connector/WinPipeConnector.java

@@ -0,0 +1,216 @@
+/*
+ * Copyright (C) 2021, 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.internal.transport.sshd.agent.connector;
+
+import java.io.IOException;
+import java.text.MessageFormat;
+import java.util.Arrays;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.apache.sshd.common.SshException;
+import org.eclipse.jgit.transport.sshd.agent.AbstractConnector;
+import org.eclipse.jgit.transport.sshd.agent.ConnectorFactory.ConnectorDescriptor;
+import org.eclipse.jgit.util.StringUtils;
+
+import com.sun.jna.LastErrorException;
+import com.sun.jna.platform.win32.WinBase;
+import com.sun.jna.platform.win32.WinError;
+import com.sun.jna.platform.win32.WinNT;
+import com.sun.jna.platform.win32.WinNT.HANDLE;
+import com.sun.jna.ptr.IntByReference;
+
+/**
+ * A connector based on JNA using Windows' named pipes to communicate with an
+ * ssh agent. This is used by Microsoft's Win32-OpenSSH port.
+ */
+public class WinPipeConnector extends AbstractConnector {
+
+	// Pipe names are, like other file names, case-insensitive on Windows.
+	private static final String CANONICAL_PIPE_NAME = "\\\\.\\pipe\\openssh-ssh-agent"; //$NON-NLS-1$
+
+	/**
+	 * {@link ConnectorDescriptor} for the {@link PageantConnector}.
+	 */
+	public static final ConnectorDescriptor DESCRIPTOR = new ConnectorDescriptor() {
+
+		@Override
+		public String getIdentityAgent() {
+			return CANONICAL_PIPE_NAME;
+		}
+
+		@Override
+		public String getDisplayName() {
+			return Texts.get().winOpenSsh;
+		}
+	};
+
+	private static final int FILE_SHARE_NONE = 0;
+
+	private static final int FILE_ATTRIBUTE_NONE = 0;
+
+	private final String pipeName;
+
+	private final AtomicBoolean connected = new AtomicBoolean();
+
+	// It's a byte pipe, so the normal Windows file mechanisms can be used.
+	// Would one of the standard Java File I/O abstractions work?
+	private volatile HANDLE fileHandle;
+
+	/**
+	 * Creates a {@link WinPipeConnector} for the given named pipe.
+	 *
+	 * @param pipeName
+	 *            to connect to
+	 */
+	public WinPipeConnector(String pipeName) {
+		this.pipeName = pipeName.replace('/', '\\');
+	}
+
+	@Override
+	public boolean connect() throws IOException {
+		if (StringUtils.isEmptyOrNull(pipeName)) {
+			return false;
+		}
+		HANDLE file = fileHandle;
+		synchronized (this) {
+			if (connected.get()) {
+				return true;
+			}
+			LibraryHolder libs = LibraryHolder.getLibrary();
+			if (libs == null) {
+				return false;
+			}
+			file = libs.kernel.CreateFile(pipeName,
+					WinNT.GENERIC_READ | WinNT.GENERIC_WRITE, FILE_SHARE_NONE,
+					null, WinNT.OPEN_EXISTING, FILE_ATTRIBUTE_NONE, null);
+			if (file == null || file == WinBase.INVALID_HANDLE_VALUE) {
+				int errorCode = libs.kernel.GetLastError();
+				if (errorCode == WinError.ERROR_FILE_NOT_FOUND
+						&& CANONICAL_PIPE_NAME.equalsIgnoreCase(pipeName)) {
+					// OpenSSH agent not running. Don't throw.
+					return false;
+				}
+				LastErrorException cause = new LastErrorException(
+						libs.systemError());
+				throw new IOException(MessageFormat
+						.format(Texts.get().msgConnectPipeFailed, pipeName),
+						cause);
+			}
+			connected.set(true);
+		}
+		fileHandle = file;
+		return connected.get();
+	}
+
+	@Override
+	public synchronized void close() throws IOException {
+		HANDLE file = fileHandle;
+		if (connected.getAndSet(false) && fileHandle != null) {
+			fileHandle = null;
+			LibraryHolder libs = LibraryHolder.getLibrary();
+			boolean success = libs.kernel.CloseHandle(file);
+			if (!success) {
+				LastErrorException cause = new LastErrorException(
+						libs.systemError());
+				throw new IOException(MessageFormat
+						.format(Texts.get().msgCloseFailed, pipeName), cause);
+			}
+		}
+	}
+
+	@Override
+	public byte[] rpc(byte command, byte[] message) throws IOException {
+		prepareMessage(command, message);
+		HANDLE file = fileHandle;
+		if (!connected.get() || file == null) {
+			// No translation, internal error
+			throw new IllegalStateException("Not connected to SSH agent"); //$NON-NLS-1$
+		}
+		LibraryHolder libs = LibraryHolder.getLibrary();
+		writeFully(libs, file, message);
+		// Now receive the reply
+		byte[] lengthBuf = new byte[4];
+		readFully(libs, file, lengthBuf);
+		int length = toLength(command, lengthBuf);
+		byte[] payload = new byte[length];
+		readFully(libs, file, payload);
+		return payload;
+	}
+
+	private void writeFully(LibraryHolder libs, HANDLE file, byte[] message)
+			throws IOException {
+		byte[] buf = message;
+		int toWrite = buf.length;
+		try {
+			while (toWrite > 0) {
+				IntByReference written = new IntByReference();
+				boolean success = libs.kernel.WriteFile(file, buf, buf.length,
+						written, null);
+				if (!success) {
+					throw new LastErrorException(libs.systemError());
+				}
+				int actuallyWritten = written.getValue();
+				toWrite -= actuallyWritten;
+				if (actuallyWritten > 0 && toWrite > 0) {
+					buf = Arrays.copyOfRange(buf, actuallyWritten, buf.length);
+				}
+			}
+		} catch (LastErrorException e) {
+			throw new IOException(MessageFormat.format(
+					Texts.get().msgSendFailed, Integer.toString(message.length),
+					Integer.toString(toWrite)), e);
+		}
+	}
+
+	private void readFully(LibraryHolder libs, HANDLE file, byte[] data)
+			throws IOException {
+		int n = 0;
+		int offset = 0;
+		while (offset < data.length && (n = read(libs, file, data, offset,
+				data.length - offset)) > 0) {
+			offset += n;
+		}
+		if (offset < data.length) {
+			throw new SshException(MessageFormat.format(
+					Texts.get().msgShortRead, Integer.toString(data.length),
+					Integer.toString(offset), Integer.toString(n)));
+		}
+	}
+
+	private int read(LibraryHolder libs, HANDLE file, byte[] buffer, int offset,
+			int length) throws IOException {
+		try {
+			int toRead = length;
+			IntByReference read = new IntByReference();
+			if (offset == 0) {
+				boolean success = libs.kernel.ReadFile(file, buffer, toRead,
+						read, null);
+				if (!success) {
+					throw new LastErrorException(libs.systemError());
+				}
+				return read.getValue();
+			}
+			byte[] data = new byte[length];
+			boolean success = libs.kernel.ReadFile(file, buffer, toRead, read,
+					null);
+			if (!success) {
+				throw new LastErrorException(libs.systemError());
+			}
+			int actuallyRead = read.getValue();
+			if (actuallyRead > 0) {
+				System.arraycopy(data, 0, buffer, offset, actuallyRead);
+			}
+			return actuallyRead;
+		} catch (LastErrorException e) {
+			throw new IOException(MessageFormat.format(
+					Texts.get().msgReadFailed, Integer.toString(length)), e);
+		}
+	}
+}

org.eclipse.jgit.ssh.apache/src/org/eclipse/jgit/internal/transport/sshd/agent/SshAgentClient.java

@@ -73,11 +73,18 @@ private boolean open(boolean debugging) throws IOException {
 			}
 			return false;
 		}
-		boolean connected = connector != null && connector.connect();
-		if (!connected) {
-			if (debugging) {
-				LOG.debug("No SSH agent (SSH_AUTH_SOCK not set)"); //$NON-NLS-1$
+		boolean connected;
+		try {
+			connected = connector != null && connector.connect();
+			if (!connected && debugging) {
+				LOG.debug("No SSH agent"); //$NON-NLS-1$
 			}
+		} catch (IOException e) {
+			// Agent not running?
+			if (debugging) {
+				LOG.debug("No SSH agent", e); //$NON-NLS-1$
+			}
+			throw e;
 		}
 		return connected;
 	}