Telnet client: Support Client-initiated Subnegotiation Messages
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Key: NET-343
URL: https://issues.apache.org/jira/browse/NET-343
Project: Commons Net
Issue Type: New Feature
Components: Telnet
Affects Versions: 2.0
Reporter: Archie Cobbs
I am in the process of trying to implement a Java client for [RFC
2217|http://tools.ietf.org/html/rfc2217], which is the protocol for accessing
serial ports over TCP. Unfortunately, the commons-net telnet client is
insufficient for this relatively simple task.
There are two missing features in the commons-net telnet client code, one of
which is a show stopper and the other of which would be a "real nice to have".
This issue documents the first problem:
RFC 2217 specifies that serial port events (such as server notifiying about a
change in carrier detect, or the client instructing the server to change the
baud rate) are delivered to the peer by subnegotiations. For example, to notify
the client about carrier detect, the server sends {{IAC SB COM-PORT-OPTION
NOTIFY-MODEMSTATE <value> IAC SE}} to the client; to set the serial port baud
rate, the client sends {{IAC SB COM-PORT-OPTION SET-BAUD <value(4)> IAC SE}} to
the server. These messages can happen at any time and are not associated with
any WILL/WONT/DO/DONT negotiation (according to my understanding).
The problem is that while one can _receive_ such messages via
{{TelnetOptionHandler.answerSubnegotiation()}}, the {{TelnetClient}} class
doesn't provide any way to _send_ (i.e., intiate) these messages.
What's needed here is simply to expose {{Telnet._sendSubnegotiation()}}
(properly renamed, etc.) as a public method.
I'm going to attempt to come up with a patch and will attach it here if
successful.
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