org.springframework.cloud.config.server.ssh.PropertyBasedSshSessionFactory.java Source code

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Here is the source code for org.springframework.cloud.config.server.ssh.PropertyBasedSshSessionFactory.java

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/*
 * Copyright 2015 - 2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.cloud.config.server.ssh;

import java.util.Map;

import com.jcraft.jsch.HostKey;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.Session;
import org.eclipse.jgit.transport.JschConfigSessionFactory;
import org.eclipse.jgit.transport.OpenSshConfig.Host;
import org.eclipse.jgit.util.Base64;
import org.eclipse.jgit.util.FS;

import org.springframework.cloud.config.server.environment.JGitEnvironmentProperties;

/**
 * In a cloud environment local SSH config files such as `.known_hosts` may not be suitable for providing
 * configuration settings due to ephemeral filesystems. This flag enables SSH config to be provided as application
 * properties
 * @author William Tran
 * @author Ollie Hughes
 */
public class PropertyBasedSshSessionFactory extends JschConfigSessionFactory {

    private static final String STRICT_HOST_KEY_CHECKING = "StrictHostKeyChecking";
    private static final String PREFERRED_AUTHENTICATIONS = "PreferredAuthentications";
    private static final String YES_OPTION = "yes";
    private static final String NO_OPTION = "no";
    private static final String SERVER_HOST_KEY = "server_host_key";
    private final Map<String, JGitEnvironmentProperties> sshKeysByHostname;
    private final JSch jSch;

    public PropertyBasedSshSessionFactory(Map<String, JGitEnvironmentProperties> sshKeysByHostname, JSch jSch) {
        this.sshKeysByHostname = sshKeysByHostname;
        this.jSch = jSch;
    }

    @Override
    protected void configure(Host hc, Session session) {
        JGitEnvironmentProperties sshProperties = sshKeysByHostname.get(hc.getHostName());
        String hostKeyAlgorithm = sshProperties.getHostKeyAlgorithm();
        if (hostKeyAlgorithm != null) {
            session.setConfig(SERVER_HOST_KEY, hostKeyAlgorithm);
        }
        if (sshProperties.getHostKey() == null || !sshProperties.isStrictHostKeyChecking()) {
            session.setConfig(STRICT_HOST_KEY_CHECKING, NO_OPTION);
        } else {
            session.setConfig(STRICT_HOST_KEY_CHECKING, YES_OPTION);
        }
        String preferredAuthentications = sshProperties.getPreferredAuthentications();
        if (preferredAuthentications != null) {
            session.setConfig(PREFERRED_AUTHENTICATIONS, preferredAuthentications);
        }
    }

    @Override
    protected Session createSession(Host hc, String user, String host, int port, FS fs) throws JSchException {
        if (sshKeysByHostname.containsKey(host)) {
            JGitEnvironmentProperties sshUriProperties = sshKeysByHostname.get(host);
            jSch.addIdentity(host, sshUriProperties.getPrivateKey().getBytes(), null, null);
            if (sshUriProperties.getKnownHostsFile() != null) {
                jSch.setKnownHosts(sshUriProperties.getKnownHostsFile());
            }
            if (sshUriProperties.getHostKey() != null) {
                HostKey hostkey = new HostKey(host, Base64.decode(sshUriProperties.getHostKey()));
                jSch.getHostKeyRepository().add(hostkey, null);
            }
            return jSch.getSession(user, host, port);
        }
        throw new JSchException("no keys configured for hostname " + host);
    }

}