On Monday, 27 November 2017 10:40:40 PM AEDT Jonathan K. Bullard wrote:
> Hi,
>
> On Mon, Nov 27, 2017 at 2:23 AM, Steven Haigh <net...@crc.id.au> wrote:
> > On 2017-11-27 05:06, Selva Nair wrote:
> >> On Sun, Nov 26, 2017 at 10:49 AM, Jonathan K. Bullard
> >>
> >> <jkbull...@gmail.com> wrote:
> >>> This:
> >>>
> >>> echo "msg This message"
> >>> echo "msg will be shown"
> >>> echo "msg"
> >>> echo "msg on four lines (the third line is empty)."
> >>> echo "msg-window the title"
> >>
> >> That nicely solves the problem of when to display the message.
> >
> > This seems to me to be a horrible solution that has been fixed in other
> > solutions for decades.
> >
> > We're doing string processing at this point - so why can't we use standard
> >
> > string formatters:
> > \n = new line
> > \r = new line
> > \t = tab
> >
> > These have been standard for as long as I can remember - and I'm getting
> > on.
> I think you're misunderstanding what program is doing what string
> processing (as I did until Selma clarified it for me).
>
> The escapes you describe ("\n", "\r", etc.) are processed by OpenVPN
> itself, not by GUIs such as Tunnelblick, and thus would already have
> been processed in the text of messages that the GUI receives from
> OpenVPN over the management interface. The only way to pass them
> through intact for the GUI to interpret them would be to
> double-backslash them (e.g. \\n), which might in some circumstances
> require yet another level (\\\\n).
>
> You can use multiple-backslash escaping for most characters if you
> want to include them in a message. However, commas cannot be included
> in strings "pushed" by the server, so we need a way to escape them
> that is _not_ processed by OpenVPN, so the escape sequence itself is
> passed intact to the GUI. Selma's proposal to use URL encoding (such
> as %2C for a comma) does just that.
Does it use \r\n or \n or \r as the end of line terminator? It may have been a
mistake to do this - and the lines probably should have been null-terminated -
but we're probably beyond fixing that at this stage.
If none of that can be done, then uri encoding scheme is probably the next
most common / well understood part of encoding for multiline / parser specific
text.
> > This would allow you to combine everything into a single command.
> >
> > I feel it is a creep in the wrong direction to get the openvpn client to
> > piece together your message. If you want to display something, it should
> > be
> > pieced together in your script, then sent to openvpn in a single, well
> > specified format.
>
> That won't work for "long" messages. (It's what I proposed until I
> understood the problems that need to be addressed.)
>
> And by "long" I mean "pretty short" : )
>
> OpenVPN options (including echo and push) are limited to about 255
> bytes. Those bytes would have to include the message itself, the
> message title, "push", "echo", whatever name we give the message
> command, and all separators, quoting and escaping. And some characters
> (all in some languages) require multiple bytes. So 255 is a very, very
> severe limitation.
I believe this should be addressed in OpenVPN anyway. There are many more
problems that could be solved with an increase in the max line size. My OTP
implementation would benefit as I've had to limit the token length to work
around this problem as well.
> So we need a convention for expressing and then combining relatively
> short pieces of a message. The "msg" and "msg-n" proposal does that:
> it allows long lines to be created (using "msg-n"), and allows
> multi-line messages without escapes ("msg", with it's implied
> newline).
--
Steven Haigh
📧 net...@crc.id.au 💻 http://www.crc.id.au
📞 +61 (3) 9001 6090 📱 0412 935 897
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