org.eclipse.n4js.utils.git.SshSessionFactory.java Source code

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Here is the source code for org.eclipse.n4js.utils.git.SshSessionFactory.java

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/**
 * Copyright (c) 2016 NumberFour AG.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   NumberFour AG - Initial API and implementation
 */
package org.eclipse.n4js.utils.git;

import static com.google.common.base.Preconditions.checkState;

import java.io.File;
import java.io.IOException;
import java.nio.charset.Charset;

import org.eclipse.jgit.transport.JschConfigSessionFactory;
import org.eclipse.jgit.transport.OpenSshConfig.Host;
import org.eclipse.jgit.util.FS;

import com.google.common.base.StandardSystemProperty;
import com.google.common.io.Files;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.Session;

/**
 * SSH session factory for JGit checkout.
 * <p>
 * This class requires to have the private key under {@code .ssh} in the home folder.
 */
/* default */ class SshSessionFactory extends JschConfigSessionFactory {

    @Override
    protected void configure(final Host host, final Session session) {
        // ignored
    }

    @Override
    protected JSch getJSch(final Host host, final FS fs) throws JSchException {
        return configureIdentity(super.getJSch(host, fs));
    }

    @Override
    protected JSch createDefaultJSch(final FS fs) throws JSchException {
        return configureIdentity(super.createDefaultJSch(fs));
    }

    private JSch configureIdentity(final JSch jsch) throws JSchException {

        final File sshDirectory = new File(StandardSystemProperty.USER_HOME.value() + "/.ssh");
        checkState(sshDirectory.exists(), ".ssh directory does not exist under home folder.");
        checkState(sshDirectory.canRead(), ".ssh directory content cannot be read.");
        checkState(sshDirectory.isDirectory(), sshDirectory.getAbsoluteFile() + " is not a directory.");
        final File[] keyFiles = sshDirectory.listFiles();
        checkState(null != keyFiles && keyFiles.length > 0, "No SSH key files exist.");

        jsch.removeAllIdentity();
        for (final File keyFile : keyFiles) {
            if (keyFile.isFile()) {
                final String keyUri = keyFile.toURI().toString();
                final int lastIndexOf = keyUri.lastIndexOf("/");
                if (lastIndexOf > 0) {
                    final String keyFileName = keyUri.substring(lastIndexOf + 1);
                    if ("id_rsa".equals(keyFileName) || "id_dsa".equals(keyFileName)) {
                        if (isEncrypted(keyFile)) {
                            String pw = getPassphrase(keyFile);
                            jsch.addIdentity(keyFile.getAbsolutePath(), pw);
                        } else {
                            jsch.addIdentity(keyFile.getAbsolutePath());
                        }

                        break;
                    }
                }
            }
        }

        return jsch;
    }

    /**
     * Tries to get passphrase for encrypted SSH key, either from system property or console. Note that running inside
     * Eclipse no console is available. In this case, the password is to be passed as system property. It can "securely"
     * be requested via prompt when starting the test from Eclipse adding
     *
     * <pre>
     * -Dorg.eclipse.n4js.ssh.pw.name=${password_prompt}
     * </pre>
     *
     * to the VM arguments (with name matching the name of the key file.
     */
    private String getPassphrase(File keyFile) {
        String name = keyFile.getName();
        String pw = System.getProperty("org.eclipse.n4js.ssh.pw." + name);
        if (pw == null) {
            if (System.console() == null) {
                String msg = "Need passphrase to decrypt ssh key \n"
                        + "Add this following line to VM arguments in debug config:\n" + "-D"
                        + "org.eclipse.n4js.ssh.pw." + name + "=${password_prompt}";
                System.err.println(msg);
                throw new IllegalStateException(msg);

            } else {
                pw = new String(System.console().readPassword("Enter passphrase for ssh key " + name));
            }
        }
        return pw;

    }

    private boolean isEncrypted(File keyFile) {
        try {
            String s = Files.asCharSource(keyFile, Charset.defaultCharset()).read();
            return s.indexOf("ENCRYPTED") >= 0;
        } catch (IOException e) {
            return false;
        }
    }
}