[Info-vax] Reverse telnet to a terminal emulator?

[VAXman- at SendSpamHere.ORG]

In article <j04nl8$q39$1 at speranza.aioe.org>, Snowshoe <no at spam.please> writes:
>On 7/19/2011 7:47 AM, VAXman- @SendSpamHere.ORG wrote:
>> In article<j02l2e$2ha$1 at speranza.aioe.org>, Snowshoe<no at spam.please>  writes:
>>> Is there any such thing as VTxxx-compatible terminal server software
>>> that runs on a PC that, instead of actively connecting to a host via
>>> telnet, is "passive", it waits until something connects to it?  Once a
>>> host connects to it, it acts like a regular VTxxx terminal.  My idea is
>>
>> There are some here, myself included, would argue that there is no
>> PeeCee software that acts like a regulat VT terminal.
>
>In my case, it doesn't really matter.  There is little if any VTxxx 
>advanced features. Currently they are using Reflections on a PC 
>connected to a hardwired RS-232 link.
>
>
>>> for VMS to reverse-telnet to it. (TELNET>  CREATE_SESSION 10.9.8.7 23 100
>>> creates TNA100: on host at IP address 10.9.8.7 port 23) This is to
>>> replace a hardwired terminal that doesn't log in, but an application
>>> currently allocates it and uses it for part of its operator interface.
>>>
>>> If the answer is "no", an alternative is for someone to use ordinary
>>> terminal server SW to telnet into the VMS host and run a do-nothing
>>> program that goes into a permanent LEF state, and VMS finds its TNAx
>>> device and writes to it, but this is one step I'd rather not have the
>>> operators do.
>>
>> Sounds like a good job for a pseudo-terminal application.  You connect
>> your PeeCee with the not-ready-for-prime-time VT terminal emulation to
>> its PTD$READ side and your application talks to its PTD device.  It's
>> a very simple thing to program.
>
>I have done this in the past, sort of. (swiped 
>SYS$EXAMPLES:ALPHA_LOGGER.C and changed the non-pseudoterminal portion) 
>  The pseudoterminal part is actually strange code if you have to tamper 
>with it, but I didn't.

What's so strange about it?

1. Allocate process memory that will be used by the Pseudo-Terminal

   $EXPREG does this nicely but you could call LIB$GET_VM[_PAGE] or,
   perhaps, even the C malloc:

        $EXPREG_S       pagcnt  = #page_count,-
                        retadr  = PTD.IO_BUFFERS

2. Create the pseudo-terminal with the terminal characteristics you
   desire.

        PTD$CREATE_S    chan    = PTD.CHANNEL,-
                        charbuff= PTD.CHAR_BUFFER,-
                        buflen  = #buffer_length,-
                        inadr   = PTD.IO_BUFFERS


3. Queue a read...

	Allocate a buffer from the memory allocated for the pseudo-
        terminal in step 1.

        PTD$READ_S      efn     = #EFN$C_ENF,-
                        chan    = PTD.CHANNEL,-
                        astadr  = PTD.READ_AST,-
                        astprm  = buffer_address,-
                        readbuf = buffer_address+8,-
                        readbuf_len = #buffer_len-8

4.  The read AST...

	Gets the buffer (passed as the AST argument)
	Do what you need to with the data.
	Put the buffer back into the allocation pool.

	Allocate a buffer from the memory allocated for the pseudo-
        terminal in step 1.

        PTD$READ_S      efn     = #EFN$C_ENF,-
                        chan    = PTD.CHANNEL,-
                        astadr  = PTD.READ_AST,-
                        astprm  = buffer_address,-
                        readbuf = buffer_address+8,-
                        readbuf_len = #buffer_len-8


There you go, I just wrote the program for you.


-- 
VAXman- A Bored Certified VMS Kernel Mode Hacker    VAXman(at)TMESIS(dot)ORG

All your spirit rack abuses, come to haunt you back by day.
All your Byzantine excuses, given time, given you away.