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Date:	Wed, 3 Jun 1998 07:40:50 PST8PDT
From:	"Gregory W. Smith" <gsmith@well.com >
Reply-To:	scoug-programming@scoug.com
To:	< "scoug-programming@scoug.com" > scoug-programming@scoug.com >
Subject:	SCOUG-Programming: GetLine()

Content Type: text/plain

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On Tue, 2 Jun 1998 23:39:49 PST8PDT, Peter Skye wrote:

>> Actually, the FTP client should NOT send backspaces -- in fact, the
>> "client" should not be sending "character" oriented data in the first
>> place, i.e., the client shouldn't send each and every keystroke of the
>> user as he or she bangs on the keyboard...
>
>> If it is a "well known fact" that the data CANNOT contain certain
>> characters [namely, NULLS or the LINE TERMINATOR itself] ...
>
>I still suggest you allow for all possibilities. If it _might_ show up,
>someday it _will_ show up.
>
>- Peter Skye

BUT, the processing of things such as backspace and all of the
end of line variations are actually part of how the control connection
is setup and the protocol interpeter (PI) portion of the server. Hate
to get legalistic here, but from section 2.3 of RFC959:

In the model described in Figure 1, the user-protocol interpreter
initiates the control connection. The control connection follows
the Telnet protocol. At the initiation of the user, standard FTP
commands are generated by the user-PI and transmitted to the
server process via the control connection. (The user may
establish a direct control connection to the server-FTP, from a
TAC terminal for example, and generate standard FTP commands
independently, bypassing the user-FTP process.) Standard replies
are sent from the server-PI to the user-PI over the control
connection in response to the commands.

... (And later in the section) .......

The Relationship between FTP and Telnet:

The FTP uses the Telnet protocol on the control connection.
This can be achieved in two ways: first, the user-PI or the
server-PI may implement the rules of the Telnet Protocol
directly in their own procedures; or, second, the user-PI or
the server-PI may make use of the existing Telnet module in the
system.

Ease of implementaion, sharing code, and modular programming
argue for the second approach. Efficiency and independence
argue for the first approach. In practice, FTP relies on very
little of the Telnet Protocol, so the first approach does not
necessarily involve a large amount of code.

The portion of Telnet that is implemented by the control connection
is discussed later in the RFC. In a nutshell, GetLine() doesn't have
to edit the input string as it comes in. If the data read by recv() has
a backspace, then that character really is a part of the data that the
PI has to parse. And all of the funky variations on the end of line
character have been negotiated before GetLine() is called.
===============================================================
Gregory W. Smith (WD9GAY) gsmith@well.com
finger gsmith@well.com for PGP public key
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