Writing a HylaFAX client...

[Jonathan Chen <jonc@pinnacle.co.nz>]

Hi y'all,

I'm seriously thinking of writing Yet-Another-HylaFAX-Client, but
the main problem I have at the moment is that I don't quite understand
just how the data-transfer from client -> host works at the moment.

The output from "sendfax -v -v" helps quite a bit:

    Trying localhost (127.0.0.1) at port 4559...
    Connected to localhost.pinnacle.co.nz.
    220 kiwi.pinnacle.co.nz server (HylaFAX (tm) Version 4.0pl1) ready.
    -> USER jonc

    [snip-text-conversion-match-stuff]

    -> TYPE I
    200 Type set to Image.
    SEND compressed data, 7938 bytes
    -> PORT 127,0,0,1,7,67
    200 PORT command successful.
    -> MODE Z
    200 Mode set to ZIP.
    -> STOT
    150 FILE: /tmp/doc179.ps (Opening new data connection).
    SEND 2900 bytes transmitted (2.7x compression)
    226 Transfer complete (FILE: /tmp/doc179.ps).
    -> JNEW
    200 New job created: jobid: 95 groupid: 95.
    -> JPARM FROMUSER "Jonathan Chen"
    213 FROMUSER set to "Jonathan Chen".
    -> JPARM LASTTIME 000300
    213 LASTTIME set to 000300.

    [snip-lotsa-JPARM-stuff]

    -> JPARM PAGECHOP "default"
    213 PAGECHOP set to "default".
    -> JPARM CHOPTHRESHOLD 3
    213 CHOPTHRESHOLD set to 3.
    SEND compressed data, 8966 bytes
    -> PORT 127,0,0,1,7,69
    200 PORT command successful.
    -> STOT
    150 FILE: /tmp/doc180.ps (Opening new data connection).
    SEND 3403 bytes transmitted (2.6x compression)
    226 Transfer complete (FILE: /tmp/doc180.ps).
    -> JPARM COVER /tmp/doc180.ps
    200 Added cover page document /tmp/doc180.ps as docq/doc95.cover.
    -> JPARM DOCUMENT /tmp/doc179.ps
    200 Added document /tmp/doc179.ps as docq/doc179.ps.95.
    -> JSUBM
    200 Job 95 submitted.

The control stuff looks pretty simple. It's the PORT command that
throws me somewhat. "127,0,0,1" refers to localhost IP-address, and
the last 2 numbers "7,67" (for the document) and "7,69" (for the
cover page) probably refers to the data port. The questions are:

    1.  how does "7,67"/"7,69" translate to a data-port?
    2.  And where did the client come up with that number? I was
        always under the impression that the server had to be `listen'ing
        on a particular port for a client connection; but nowhere in
        the transcript did the HylaFAX server indicate which port the
        client should use.

Help, anyone? I basically don't want to wade thru' the HylaFAX code at
the moment..
--
Jonathan Chen                          e-mail : jonc@pinnacle.co.nz
  Pinnacle Software Ltd                Voice  : +64.9.415.4460
  Auckland, New Zealand                Fax    : +64.9.415.4250