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1 /*
2 * SSHTools - Java SSH2 API
3 *
4 * Copyright (C) 2002-2003 Lee David Painter and Contributors.
5 *
6 * Contributions made by:
7 *
8 * Brett Smith
9 * Richard Pernavas
10 * Erwin Bolwidt
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version 2
15 * of the License, or (at your option) any later version.
16 *
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
21 *
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
25 */
26 package com.sshtools.j2ssh.transport;
27
28 import com.sshtools.j2ssh.transport.publickey.SshPublicKey;
29
30 import java.io.BufferedReader;
31 import java.io.File;
32 import java.io.IOException;
33 import java.io.InputStreamReader;
34
35
36 /**
37 * <p>
38 * Implements the <code>AbstractKnownHostsKeyVerification</code> to provide
39 * host key verification through the console.
40 * </p>
41 *
42 * @author Lee David Painter
43 * @version $Revision: 1.14 $
44 *
45 * @since 0.2.0
46 */
47 public class ConsoleKnownHostsKeyVerification
48 extends AbstractKnownHostsKeyVerification {
49 /**
50 * <p>
51 * Constructs the verification instance with the default known_hosts file
52 * from $HOME/.ssh/known_hosts.
53 * </p>
54 *
55 * @throws InvalidHostFileException if the known_hosts file is invalid.
56 *
57 * @since 0.2.0
58 */
59 public ConsoleKnownHostsKeyVerification() throws InvalidHostFileException {
60 super(new File(System.getProperty("user.home"),
61 ".ssh" + File.separator + "known_hosts").getAbsolutePath());
62 }
63
64 /**
65 * <p>
66 * Constructs the verification instance with the specified known_hosts
67 * file.
68 * </p>
69 *
70 * @param knownhosts the path to the known_hosts file
71 *
72 * @throws InvalidHostFileException if the known_hosts file is invalid.
73 *
74 * @since 0.2.0
75 */
76 public ConsoleKnownHostsKeyVerification(String knownhosts)
77 throws InvalidHostFileException {
78 super(knownhosts);
79 }
80
81 /**
82 * <p>
83 * Prompts the user through the console to verify the host key.
84 * </p>
85 *
86 * @param host the name of the host
87 * @param pk the current public key of the host
88 * @param actual the actual public key supplied by the host
89 *
90 * @since 0.2.0
91 */
92 public void onHostKeyMismatch(String host, SshPublicKey pk,
93 SshPublicKey actual) {
94 try {
95 System.out.println("The host key supplied by " + host + " is: " +
96 actual.getFingerprint());
97 System.out.println("The current allowed key for " + host + " is: " +
98 pk.getFingerprint());
99 getResponse(host, pk);
100 } catch (Exception e) {
101 e.printStackTrace();
102 }
103 }
104
105 /**
106 * <p>
107 * Prompts the user through the console to verify the host key.
108 * </p>
109 *
110 * @param host the name of the host
111 * @param pk the public key supplied by the host
112 *
113 * @since 0.2.0
114 */
115 public void onUnknownHost(String host, SshPublicKey pk) {
116 try {
117 System.out.println("The host " + host +
118 " is currently unknown to the system");
119 System.out.println("The host key fingerprint is: " +
120 pk.getFingerprint());
121 getResponse(host, pk);
122 } catch (Exception e) {
123 e.printStackTrace();
124 }
125 }
126
127 private void getResponse(String host, SshPublicKey pk)
128 throws InvalidHostFileException, IOException {
129 String response = "";
130 BufferedReader reader = new BufferedReader(new InputStreamReader(
131 System.in));
132
133 while (!(response.equalsIgnoreCase("YES") ||
134 response.equalsIgnoreCase("NO") ||
135 (response.equalsIgnoreCase("ALWAYS") && isHostFileWriteable()))) {
136 String options = (isHostFileWriteable() ? "Yes|No|Always" : "Yes|No");
137
138 if (!isHostFileWriteable()) {
139 System.out.println(
140 "Always option disabled, host file is not writeable");
141 }
142
143 System.out.print("Do you want to allow this host key? [" + options +
144 "]: ");
145 response = reader.readLine();
146 }
147
148 if (response.equalsIgnoreCase("YES")) {
149 allowHost(host, pk, false);
150 }
151
152 if (response.equalsIgnoreCase("NO")) {
153 System.out.println("Cannot continue without a valid host key");
154 System.exit(1);
155 }
156
157 if (response.equalsIgnoreCase("ALWAYS") && isHostFileWriteable()) {
158 allowHost(host, pk, true);
159 }
160 }
161 }