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2 package com.trilead.ssh2;
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3
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4 import java.io.IOException;
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5 import java.io.InputStream;
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6 import java.io.OutputStream;
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7 import java.security.SecureRandom;
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8
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9 import com.trilead.ssh2.channel.Channel;
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10 import com.trilead.ssh2.channel.ChannelManager;
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11 import com.trilead.ssh2.channel.X11ServerData;
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12
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13
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14 /**
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15 * A <code>Session</code> is a remote execution of a program. "Program" means
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16 * in this context either a shell, an application or a system command. The
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17 * program may or may not have a tty. Only one single program can be started on
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18 * a session. However, multiple sessions can be active simultaneously.
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19 *
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20 * @author Christian Plattner, plattner@trilead.com
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21 * @version $Id: Session.java,v 1.2 2008/03/03 07:01:36 cplattne Exp $
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22 */
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23 public class Session {
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24 ChannelManager cm;
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25 Channel cn;
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26
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27 boolean flag_pty_requested = false;
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28 boolean flag_x11_requested = false;
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29 boolean flag_execution_started = false;
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30 boolean flag_closed = false;
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31
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32 String x11FakeCookie = null;
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33
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34 final SecureRandom rnd;
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35
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36 Session(ChannelManager cm, SecureRandom rnd) throws IOException {
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37 this.cm = cm;
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38 this.cn = cm.openSessionChannel();
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39 this.rnd = rnd;
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40 }
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41
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42 /**
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43 * Basically just a wrapper for lazy people - identical to calling
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44 * <code>requestPTY("dumb", 0, 0, 0, 0, null)</code>.
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45 *
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46 * @throws IOException
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47 */
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48 public void requestDumbPTY() throws IOException {
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49 requestPTY("dumb", 0, 0, 0, 0, null);
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50 }
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51
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52 /**
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53 * Basically just another wrapper for lazy people - identical to calling
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54 * <code>requestPTY(term, 0, 0, 0, 0, null)</code>.
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55 *
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56 * @throws IOException
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57 */
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58 public void requestPTY(String term) throws IOException {
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59 requestPTY(term, 0, 0, 0, 0, null);
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60 }
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61
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62 /**
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63 * Allocate a pseudo-terminal for this session.
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64 * <p>
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65 * This method may only be called before a program or shell is started in
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66 * this session.
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67 * <p>
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68 * Different aspects can be specified:
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69 * <p>
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70 * <ul>
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71 * <li>The TERM environment variable value (e.g., vt100)</li>
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72 * <li>The terminal's dimensions.</li>
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73 * <li>The encoded terminal modes.</li>
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74 * </ul>
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75 * Zero dimension parameters are ignored. The character/row dimensions
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76 * override the pixel dimensions (when nonzero). Pixel dimensions refer to
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77 * the drawable area of the window. The dimension parameters are only
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78 * informational. The encoding of terminal modes (parameter
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79 * <code>terminal_modes</code>) is described in RFC4254.
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80 *
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81 * @param term
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82 * The TERM environment variable value (e.g., vt100)
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83 * @param term_width_characters
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84 * terminal width, characters (e.g., 80)
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85 * @param term_height_characters
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86 * terminal height, rows (e.g., 24)
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87 * @param term_width_pixels
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88 * terminal width, pixels (e.g., 640)
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89 * @param term_height_pixels
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90 * terminal height, pixels (e.g., 480)
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91 * @param terminal_modes
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92 * encoded terminal modes (may be <code>null</code>)
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93 * @throws IOException
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94 */
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95 public void requestPTY(String term, int term_width_characters, int term_height_characters, int term_width_pixels,
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96 int term_height_pixels, byte[] terminal_modes) throws IOException {
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97 if (term == null)
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98 throw new IllegalArgumentException("TERM cannot be null.");
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99
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100 if ((terminal_modes != null) && (terminal_modes.length > 0)) {
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101 if (terminal_modes[terminal_modes.length - 1] != 0)
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102 throw new IOException("Illegal terminal modes description, does not end in zero byte");
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103 }
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104 else
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105 terminal_modes = new byte[] { 0 };
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106
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107 synchronized (this) {
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108 /* The following is just a nicer error, we would catch it anyway later in the channel code */
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109 if (flag_closed)
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110 throw new IOException("This session is closed.");
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111
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112 if (flag_pty_requested)
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113 throw new IOException("A PTY was already requested.");
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114
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115 if (flag_execution_started)
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116 throw new IOException(
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117 "Cannot request PTY at this stage anymore, a remote execution has already started.");
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118
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119 flag_pty_requested = true;
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120 }
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121
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122 cm.requestPTY(cn, term, term_width_characters, term_height_characters, term_width_pixels, term_height_pixels,
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123 terminal_modes);
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124 }
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125
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126 /**
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127 * Inform other side of connection that our PTY has resized.
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128 * <p>
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129 * Zero dimension parameters are ignored. The character/row dimensions
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130 * override the pixel dimensions (when nonzero). Pixel dimensions refer to
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131 * the drawable area of the window. The dimension parameters are only
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132 * informational.
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133 *
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134 * @param term_width_characters
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135 * terminal width, characters (e.g., 80)
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136 * @param term_height_characters
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137 * terminal height, rows (e.g., 24)
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138 * @param term_width_pixels
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139 * terminal width, pixels (e.g., 640)
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140 * @param term_height_pixels
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141 * terminal height, pixels (e.g., 480)
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142 * @throws IOException
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143 */
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144 public void resizePTY(int term_width_characters, int term_height_characters, int term_width_pixels,
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145 int term_height_pixels) throws IOException {
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146 synchronized (this) {
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147 /* The following is just a nicer error, we would catch it anyway later in the channel code */
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148 if (flag_closed)
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149 throw new IOException("This session is closed.");
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150 }
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151
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152 cm.resizePTY(cn, term_width_characters, term_height_characters, term_width_pixels, term_height_pixels);
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153 }
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154
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155 /**
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156 * Request X11 forwarding for the current session.
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157 * <p>
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158 * You have to supply the name and port of your X-server.
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159 * <p>
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160 * This method may only be called before a program or shell is started in
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161 * this session.
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162 *
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163 * @param hostname the hostname of the real (target) X11 server (e.g., 127.0.0.1)
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164 * @param port the port of the real (target) X11 server (e.g., 6010)
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165 * @param cookie if non-null, then present this cookie to the real X11 server
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166 * @param singleConnection if true, then the server is instructed to only forward one single
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167 * connection, no more connections shall be forwarded after first, or after the session
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168 * channel has been closed
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169 * @throws IOException
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170 */
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171 public void requestX11Forwarding(String hostname, int port, byte[] cookie, boolean singleConnection)
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172 throws IOException {
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173 if (hostname == null)
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174 throw new IllegalArgumentException("hostname argument may not be null");
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175
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176 synchronized (this) {
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177 /* The following is just a nicer error, we would catch it anyway later in the channel code */
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178 if (flag_closed)
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179 throw new IOException("This session is closed.");
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180
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181 if (flag_x11_requested)
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182 throw new IOException("X11 forwarding was already requested.");
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183
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184 if (flag_execution_started)
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185 throw new IOException(
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186 "Cannot request X11 forwarding at this stage anymore, a remote execution has already started.");
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187
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188 flag_x11_requested = true;
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189 }
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190
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191 /* X11ServerData - used to store data about the target X11 server */
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192 X11ServerData x11data = new X11ServerData();
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193 x11data.hostname = hostname;
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194 x11data.port = port;
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195 x11data.x11_magic_cookie = cookie; /* if non-null, then present this cookie to the real X11 server */
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196 /* Generate fake cookie - this one is used between remote clients and our proxy */
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197 byte[] fakeCookie = new byte[16];
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198 String hexEncodedFakeCookie;
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199
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200 /* Make sure that this fake cookie is unique for this connection */
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201
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202 while (true) {
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203 rnd.nextBytes(fakeCookie);
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204 /* Generate also hex representation of fake cookie */
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205 StringBuffer tmp = new StringBuffer(32);
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206
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207 for (int i = 0; i < fakeCookie.length; i++) {
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208 String digit2 = Integer.toHexString(fakeCookie[i] & 0xff);
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209 tmp.append((digit2.length() == 2) ? digit2 : "0" + digit2);
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210 }
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211
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212 hexEncodedFakeCookie = tmp.toString();
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213
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214 /* Well, yes, chances are low, but we want to be on the safe side */
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215
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216 if (cm.checkX11Cookie(hexEncodedFakeCookie) == null)
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217 break;
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218 }
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219
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220 /* Ask for X11 forwarding */
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221 cm.requestX11(cn, singleConnection, "MIT-MAGIC-COOKIE-1", hexEncodedFakeCookie, 0);
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222
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223 /* OK, that went fine, get ready to accept X11 connections... */
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224 /* ... but only if the user has not called close() in the meantime =) */
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225
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226 synchronized (this) {
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227 if (flag_closed == false) {
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228 this.x11FakeCookie = hexEncodedFakeCookie;
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229 cm.registerX11Cookie(hexEncodedFakeCookie, x11data);
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230 }
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231 }
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232
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233 /* Now it is safe to start remote X11 programs */
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234 }
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235
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236 /**
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237 * Execute a command on the remote machine.
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238 *
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239 * @param cmd
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240 * The command to execute on the remote host.
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241 * @throws IOException
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242 */
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243 public void execCommand(String cmd) throws IOException {
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244 if (cmd == null)
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245 throw new IllegalArgumentException("cmd argument may not be null");
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246
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247 synchronized (this) {
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248 /* The following is just a nicer error, we would catch it anyway later in the channel code */
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249 if (flag_closed)
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250 throw new IOException("This session is closed.");
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251
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252 if (flag_execution_started)
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253 throw new IOException("A remote execution has already started.");
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254
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255 flag_execution_started = true;
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256 }
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257
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258 cm.requestExecCommand(cn, cmd);
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259 }
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260
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261 /**
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262 * Start a shell on the remote machine.
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263 *
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264 * @throws IOException
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265 */
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266 public void startShell() throws IOException {
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267 synchronized (this) {
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268 /* The following is just a nicer error, we would catch it anyway later in the channel code */
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269 if (flag_closed)
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270 throw new IOException("This session is closed.");
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271
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272 if (flag_execution_started)
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273 throw new IOException("A remote execution has already started.");
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274
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275 flag_execution_started = true;
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276 }
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277
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278 cm.requestShell(cn);
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279 }
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280
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281 /**
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282 * Start a subsystem on the remote machine.
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283 * Unless you know what you are doing, you will never need this.
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284 *
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285 * @param name the name of the subsystem.
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286 * @throws IOException
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287 */
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288 public void startSubSystem(String name) throws IOException {
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289 if (name == null)
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290 throw new IllegalArgumentException("name argument may not be null");
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291
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292 synchronized (this) {
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293 /* The following is just a nicer error, we would catch it anyway later in the channel code */
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294 if (flag_closed)
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295 throw new IOException("This session is closed.");
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296
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297 if (flag_execution_started)
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298 throw new IOException("A remote execution has already started.");
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299
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300 flag_execution_started = true;
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301 }
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302
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303 cm.requestSubSystem(cn, name);
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304 }
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305
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306 /**
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307 * This method can be used to perform end-to-end session (i.e., SSH channel)
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308 * testing. It sends a 'ping' message to the server and waits for the 'pong'
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309 * from the server.
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310 * <p>
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311 * Implementation details: this method sends a SSH_MSG_CHANNEL_REQUEST request
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312 * ('trilead-ping') to the server and waits for the SSH_MSG_CHANNEL_FAILURE reply
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313 * packet.
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314 *
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315 * @throws IOException in case of any problem or when the session is closed
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316 */
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317 public void ping() throws IOException {
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318 synchronized (this) {
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319 /*
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320 * The following is just a nicer error, we would catch it anyway
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321 * later in the channel code
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322 */
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323 if (flag_closed)
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324 throw new IOException("This session is closed.");
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325 }
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326
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327 cm.requestChannelTrileadPing(cn);
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328 }
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329
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330 /**
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331 * Request authentication agent forwarding.
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332 * @param agent object that implements the callbacks
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333 *
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334 * @throws IOException in case of any problem or when the session is closed
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335 */
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336
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337 public synchronized boolean requestAuthAgentForwarding(AuthAgentCallback agent) throws IOException {
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338 synchronized (this) {
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339 /*
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340 * The following is just a nicer error, we would catch it anyway
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341 * later in the channel code
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342 */
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343 if (flag_closed)
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344 throw new IOException("This session is closed.");
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345 }
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346
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347 return cm.requestChannelAgentForwarding(cn, agent);
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348 }
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349
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350 public InputStream getStdout() {
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351 return cn.getStdoutStream();
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352 }
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353
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354 public InputStream getStderr() {
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355 return cn.getStderrStream();
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356 }
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357
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358 public OutputStream getStdin() {
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359 return cn.getStdinStream();
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360 }
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361
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362 /**
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363 * This method blocks until there is more data available on either the
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364 * stdout or stderr InputStream of this <code>Session</code>. Very useful
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365 * if you do not want to use two parallel threads for reading from the two
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366 * InputStreams. One can also specify a timeout. NOTE: do NOT call this
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367 * method if you use concurrent threads that operate on either of the two
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368 * InputStreams of this <code>Session</code> (otherwise this method may
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369 * block, even though more data is available).
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370 *
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371 * @param timeout
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372 * The (non-negative) timeout in <code>ms</code>. <code>0</code> means no
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373 * timeout, the call may block forever.
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374 * @return
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375 * <ul>
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376 * <li><code>0</code> if no more data will arrive.</li>
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377 * <li><code>1</code> if more data is available.</li>
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378 * <li><code>-1</code> if a timeout occurred.</li>
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379 * </ul>
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380 *
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381 * @throws IOException
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382 * @deprecated This method has been replaced with a much more powerful wait-for-condition
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383 * interface and therefore acts only as a wrapper.
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384 *
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385 */
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386 public int waitUntilDataAvailable(long timeout) throws IOException {
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387 if (timeout < 0)
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388 throw new IllegalArgumentException("timeout must not be negative!");
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389
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390 int conditions = cm.waitForCondition(cn, timeout, ChannelCondition.STDOUT_DATA | ChannelCondition.STDERR_DATA
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391 | ChannelCondition.EOF);
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392
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393 if ((conditions & ChannelCondition.TIMEOUT) != 0)
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394 return -1;
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395
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396 if ((conditions & (ChannelCondition.STDOUT_DATA | ChannelCondition.STDERR_DATA)) != 0)
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397 return 1;
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398
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399 /* Here we do not need to check separately for CLOSED, since CLOSED implies EOF */
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400
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401 if ((conditions & ChannelCondition.EOF) != 0)
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402 return 0;
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403
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404 throw new IllegalStateException("Unexpected condition result (" + conditions + ")");
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405 }
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406
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407 /**
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408 * This method blocks until certain conditions hold true on the underlying SSH-2 channel.
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409 * <p>
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410 * This method returns as soon as one of the following happens:
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411 * <ul>
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412 * <li>at least of the specified conditions (see {@link ChannelCondition}) holds true</li>
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413 * <li>timeout > 0 and a timeout occured (TIMEOUT will be set in result conditions)</a>
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414 * <li>the underlying channel was closed (CLOSED will be set in result conditions)</a>
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415 * </ul>
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416 * <p>
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417 * In any case, the result value contains ALL current conditions, which may be more
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418 * than the specified condition set (i.e., never use the "==" operator to test for conditions
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419 * in the bitmask, see also comments in {@link ChannelCondition}).
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420 * <p>
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421 * Note: do NOT call this method if you want to wait for STDOUT_DATA or STDERR_DATA and
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422 * there are concurrent threads (e.g., StreamGobblers) that operate on either of the two
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423 * InputStreams of this <code>Session</code> (otherwise this method may
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424 * block, even though more data is available in the StreamGobblers).
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425 *
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426 * @param condition_set a bitmask based on {@link ChannelCondition} values
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427 * @param timeout non-negative timeout in ms, <code>0</code> means no timeout
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428 * @return all bitmask specifying all current conditions that are true
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429 */
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430
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431 public int waitForCondition(int condition_set, long timeout) {
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432 if (timeout < 0)
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433 throw new IllegalArgumentException("timeout must be non-negative!");
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434
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435 return cm.waitForCondition(cn, timeout, condition_set);
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436 }
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437
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438 /**
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439 * Get the exit code/status from the remote command - if available. Be
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440 * careful - not all server implementations return this value. It is
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441 * generally a good idea to call this method only when all data from the
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442 * remote side has been consumed (see also the <code<WaitForCondition</code> method).
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443 *
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444 * @return An <code>Integer</code> holding the exit code, or
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445 * <code>null</code> if no exit code is (yet) available.
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446 */
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447 public Integer getExitStatus() {
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448 return cn.getExitStatus();
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449 }
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450
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451 /**
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452 * Get the name of the signal by which the process on the remote side was
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453 * stopped - if available and applicable. Be careful - not all server
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454 * implementations return this value.
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455 *
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456 * @return An <code>String</code> holding the name of the signal, or
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457 * <code>null</code> if the process exited normally or is still
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458 * running (or if the server forgot to send this information).
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459 */
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460 public String getExitSignal() {
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461 return cn.getExitSignal();
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462 }
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463
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464 /**
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465 * Close this session. NEVER forget to call this method to free up resources -
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466 * even if you got an exception from one of the other methods (or when
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467 * getting an Exception on the Input- or OutputStreams). Sometimes these other
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468 * methods may throw an exception, saying that the underlying channel is
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469 * closed (this can happen, e.g., if the other server sent a close message.)
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470 * However, as long as you have not called the <code>close()</code>
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471 * method, you may be wasting (local) resources.
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472 *
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473 */
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474 public void close() {
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475 synchronized (this) {
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476 if (flag_closed)
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477 return;
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478
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479 flag_closed = true;
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480
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481 if (x11FakeCookie != null)
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482 cm.unRegisterX11Cookie(x11FakeCookie, true);
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483
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484 try {
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485 cm.closeChannel(cn, "Closed due to user request", true);
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486 }
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487 catch (IOException ignored) {
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488 }
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489 }
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490 }
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491 }
|
