Class socket.TelnetWrapper 
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Class socket.TelnetWrapper 

java.lang.Object
   |
   +----socket.TelnetWrapper
public class TelnetWrapper
extends Object
Wrapper for a Java Telnet call. To use, make a new TelnetWrapper() with the name or IP address of a host. Then, for most uses, the easiest way is to call setPrompt() with the expected prompt, then call login(), and a sequence of sendLine()'s until you get what you want done.

If you don't know the prompt ahead of time, you have to do a sequence of send() and wait() or receiveUntil() calls. send() sends a string across the telnet connection. Add a '\r' to the end if you want to complete a command. wait() waits for an exact string from the other side of the telnet connection, and returns nothing, receiveUntil() also waits for a string, but returns all the data that it received while waiting, including the string itself. Use this if you want the output from a command. Please note that the telnet connection will usually echo the sent command.

sendLine() is generally better, since it adds the '\r' automatically, waits for the prompt before returning, and returns all data received before the prompt, with the prompt itself cut off the end, and the sent command cut off the beginning. login() and sendLine() are implemented using send(), wait() and receiveUntil(). They can be freely mixed and matched.

Here is a simple example of the use of TelnetWrapper: 

// creates a new file in /tmp, lists the directory to prove it done
{
  TelnetWrapper telnet = new TelnetWrapper("123.45.78.90");
  // setting the correct prompt ahead of time is very important 
  // if you want to use login and sendLine
  telnet.setPrompt("$ ");
  telnet.login("loginname", "password");
  // this is how you have to do it otherwise
  telnet.send("touch /tmp/TELNET_WRAPPER" + "\r");
  telnet.wait("$ ");
  // sendLine 1: adds the \r automatically, 2: waits for the prompt
  // before returning 3: returns what was printed from the command
  String ls = telnet.sendLine("ls /tmp");
  System.out.println(ls);
  // clean up
  telnet.disconnect();
}
Version:
0.2 5/15/97 - added comments, replaced String += with StringBuffer.append() in receiveUntil(), added port constructor
Author:
George Ruban 3/4/97
See Also:
TelnetIO

Variable Index

o debug
Set to true for System.out.println debugging.

Constructor Index

o TelnetWrapper(String)
Connects to the default telnet port on the given host.
o TelnetWrapper(String, int)
Connects to a specific telnet port on the given host.

Method Index

o available()
Returns bytes available to be read.
o disconnect()
Ends the telnet connection.
o finalize()
Ends the telnet connection.
o login(String, String)
Logs in as a particular user and password.
o main(String[])
Telnet test driver.
o receive()
Returns a String from the telnet connection.
o receiveBytes()
Returns a byte array.
o receiveUntil(String)
Returns all data received up until a certain token.
o receiveUntil(String, long)
Returns all data received up until a certain token.
o send(byte[])
Sends bytes over the telnet connection.
o send(String)
Sends a String to the remote host.
o sendLine(String)
Sends a line to the remote host, returns all data before the prompt.
o setDefaultPrompt(String)
Sets the default prompt used by all TelnetWrappers.
o setLogin(String, String)
Sets the default login used by TelnetWrappers.
o setPrompt(String)
Sets the expected prompt.
o unsetLogin()
Turns off the default login of TelnetWrappers.
o wait(String)
Skip any received data until the token appears.
o wait(String, long)
Wait for a String or a timeout.

Variables

o debug 
  public boolean debug
Set to true for System.out.println debugging.

Constructors

o TelnetWrapper 
  public TelnetWrapper(String host) throws IOException
Connects to the default telnet port on the given host. If the defaultLogin and defaultPassword are non-null, attempts login.
o TelnetWrapper 
  public TelnetWrapper(String host,
                       int port) throws IOException
Connects to a specific telnet port on the given host. If the defaultLogin and defaultPassword are non-null, attempts login.

Methods

o wait 
  public void wait(String token) throws IOException
Skip any received data until the token appears. More efficient than receiveUntil, but liable to fail on large tokens that can be spread over several "send"s. In that case, consider using receiveUntil and ignoring the return value.
Parameters:
token - String to wait for
Throws: IOException
on problems with the socket connection
See Also:
receiveUntil
o wait 
  public void wait(String token,
                   long timeout) throws IOException, TimedOutException
Wait for a String or a timeout. If time runs out, throws a TimedOutException. Sleeps in intervals of 100 milliseconds until either receiving the token or timeout.

More efficient than receiveUntil, but liable to fail on large tokens that can be spread over several "send"s. In that case, consider using receiveUntil and ignoring the return value.

Parameters:
token - String to wait for
timeout - time in milliseconds to wait (negative means wait forever)
Throws: IOException
on problems with the socket connection
Throws: TimedOutException
if time runs out before token received
See Also:
receiveUntil
o available 
  public int available() throws IOException
Returns bytes available to be read. Since they haven't been negotiated over, this could be misleading...
o receive 
  public String receive() throws IOException
Returns a String from the telnet connection. Blocks until one is available. No guarantees that the string is in any way complete. NOTE: uses Java 1.0.2 style String-bytes conversion.
o receiveBytes 
  public byte[] receiveBytes() throws IOException
Returns a byte array. Blocks until data is available.
o receiveUntil 
  public String receiveUntil(String token) throws IOException
Returns all data received up until a certain token.
Parameters:
token - String to wait for
Throws: IOException
on problems with the socket connection
See Also:
wait
o receiveUntil 
  public String receiveUntil(String token,
                             long timeout) throws IOException, TimedOutException
Returns all data received up until a certain token.
Parameters:
token - String to wait for
timeout - time in milliseconds to wait (negative means wait forever)
Throws: IOException
on problems with the socket connection
Throws: TimedOutException
if time runs out before token received
See Also:
wait
o send 
  public void send(String s) throws IOException
Sends a String to the remote host. NOTE: uses Java 1.0.2 style String-bytes conversion.
Throws: IOException
on problems with the socket connection
o sendLine 
  public String sendLine(String command) throws IOException
Sends a line to the remote host, returns all data before the prompt. Since telnet seems to rely on carriage returns ('\r'), one will be appended to the sent string, if necessary.
Parameters:
command - command line to send
Returns:
whatever data the command produced before the prompt.
See Also:
setPrompt
o send 
  public void send(byte buf[]) throws IOException
Sends bytes over the telnet connection.
o login 
  public void login(String loginName,
                    String password) throws IOException
Logs in as a particular user and password. Returns after receiving prompt.
o setPrompt 
  public void setPrompt(String prompt)
Sets the expected prompt. If this function is not explicitly called, the default prompt is used.
See Also:
setDefaultPrompt
o setDefaultPrompt 
  public static void setDefaultPrompt(String prompt)
Sets the default prompt used by all TelnetWrappers. This can be specifically overridden for a specific instance. The default prompt starts out as "$ " until this function is called.
See Also:
setPrompt
o setLogin 
  public static void setLogin(String login,
                              String password)
Sets the default login used by TelnetWrappers. If this method is called with non-null login and password, all TelnetWrappers will attempt to login when first created.
Parameters:
login - login name to use
password - password to use
See Also:
login, unsetLogin
o unsetLogin 
  public static void unsetLogin()
Turns off the default login of TelnetWrappers. After this method is called, TelnetWrappers will not login until that method is explicitly called.
See Also:
setLogin, login
o disconnect 
  public void disconnect() throws IOException
Ends the telnet connection.
o finalize 
  public void finalize()
Ends the telnet connection.
Overrides:
finalize in class Object
o main 
  public static void main(String args[]) throws IOException
Telnet test driver. Modeled after the IOtest.java example in the Telnet Applet. Logs in to "host", creates a timestamped file in /tmp, lists the /tmp directory to System.out, disconnects. Shows off several TelnetWrapper methods.
Parameters:
args - host login password prompt 
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