Class RExecClient
- Direct Known Subclasses:
RCommandClient
As with virtually all of the client classes in com.oroinc.net, this class derives from SocketClient, inheriting its connection methods. The way to use RExecClient is to first connect to the server, call the rexec() method, and then fetch the connection's input, output, and optionally error streams. Interaction with the remote command is controlled entirely through the I/O streams. Once you have finished processing the streams, you should invoke disconnect() to clean up properly.
By default the standard output and standard error streams of the
remote process are transmitted over the same connection, readable
from the input stream returned by
getInputStream() . However, it is
possible to tell the rexecd daemon to return the standard error
stream over a separate connection, readable from the input stream
returned by getErrorStream() . You
can specify that a separate connection should be created for standard
error by setting the boolean separateErrorStream
parameter of rexec() to true
.
The standard input of the remote process can be written to through
the output stream returned by
getOutputSream() .
- Author:
- Daniel F. Savarese
- See Also:
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Field Summary
FieldsModifier and TypeFieldDescriptionprotected InputStream
If a separate error stream is requested,_errorStream_
will point to an InputStream from which the standard error of the remote process can be read (after a call to rexec()).static final int
The default rexec port.Fields inherited from class com.oroinc.net.SocketClient
_defaultPort_, _input_, _isConnected_, _output_, _socket_, _socketFactory_, _timeout_, NETASCII_EOL
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
Disconnects from the server, closing all associated open sockets and streams.Returns the InputStream from which the standard error of the remote process can be read if a separate error stream is requested from the server.Returns the InputStream from which the standard outputof the remote process can be read.Returns the OutputStream through which the standard input of the remote process can be written.final boolean
Return whether or not verification of the remote host providing a separate error stream is enabled.void
Same asrexec(username, password, command, false);
void
Remotely executes a command through the rexecd daemon on the server to which the RExecClient is connected.final void
setRemoteVerificationEnabled
(boolean enable) Enable or disable verification that the remote host connecting to create a separate error stream is the same as the host to which the standard out stream is connected.Methods inherited from class com.oroinc.net.SocketClient
_connectAction_, connect, connect, connect, connect, connect, connect, getDefaultPort, getDefaultTimeout, getLocalAddress, getLocalPort, getRemoteAddress, getRemotePort, getSoLinger, getSoTimeout, getTcpNoDelay, isConnected, setDefaultPort, setDefaultTimeout, setSocketFactory, setSoLinger, setSoTimeout, setTcpNoDelay, verifyRemote
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Field Details
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DEFAULT_PORT
public static final int DEFAULT_PORTThe default rexec port. Set to 512 in BSD Unix.- See Also:
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_errorStream_
If a separate error stream is requested,_errorStream_
will point to an InputStream from which the standard error of the remote process can be read (after a call to rexec()). Otherwise,_errorStream_
will be null.
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Constructor Details
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RExecClient
public RExecClient()The default RExecClient constructor. Initializes the default port toDEFAULT_PORT
.
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Method Details
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getInputStream
Returns the InputStream from which the standard outputof the remote process can be read. The input stream will only be set after a successful rexec() invocation.- Returns:
- The InputStream from which the standard output of the remote process can be read.
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getOutputStream
Returns the OutputStream through which the standard input of the remote process can be written. The output stream will only be set after a successful rexec() invocation.- Returns:
- The OutputStream through which the standard input of the remote process can be written.
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getErrorStream
Returns the InputStream from which the standard error of the remote process can be read if a separate error stream is requested from the server. Otherwise, null will be returned. The error stream will only be set after a successful rexec() invocation.- Returns:
- The InputStream from which the standard error of the remote process can be read if a separate error stream is requested from the server. Otherwise, null will be returned.
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rexec
public void rexec(String username, String password, String command, boolean separateErrorStream) throws IOException Remotely executes a command through the rexecd daemon on the server to which the RExecClient is connected. After calling this method, you may interact with the remote process through its standard input, output, and error streams. You will typically be able to detect the termination of the remote process after reaching end of file on its standard output (accessible through getInputStream() . Disconnecting from the server or closing the process streams before reaching end of file will not necessarily terminate the remote process.If a separate error stream is requested, the remote server will connect to a local socket opened by RExecClient, providing an independent stream through which standard error will be transmitted. RExecClient will do a simple security check when it accepts a connection for this error stream. If the connection does not originate from the remote server, an IOException will be thrown. This serves as a simple protection against possible hijacking of the error stream by an attacker monitoring the rexec() negotiation. You may disable this behavior with setRemoteVerificationEnabled().
- Parameters:
username
- The account name on the server through which to execute the command.password
- The plain text password of the user account.command
- The command, including any arguments, to execute.separateErrorStream
- True if you would like the standard error to be transmitted through a different stream than standard output. False if not.- Throws:
IOException
- If the rexec() attempt fails. The exception will contain a message indicating the nature of the failure.
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rexec
Same asrexec(username, password, command, false);
- Throws:
IOException
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disconnect
Disconnects from the server, closing all associated open sockets and streams.- Overrides:
disconnect
in classSocketClient
- Throws:
IOException
- If there an error occurs while disconnecting.
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setRemoteVerificationEnabled
public final void setRemoteVerificationEnabled(boolean enable) Enable or disable verification that the remote host connecting to create a separate error stream is the same as the host to which the standard out stream is connected. The default is for verification to be enabled. You may set this value at any time, whether the client is currently connected or not.- Parameters:
enable
- True to enable verification, false to disable verification.
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isRemoteVerificationEnabled
public final boolean isRemoteVerificationEnabled()Return whether or not verification of the remote host providing a separate error stream is enabled. The default behavior is for verification to be enabled.- Returns:
- True if verification is enabled, false if not.
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