Rani Ahmad gave me permission to forward to rivet-dev his proposal for an
alternate way to force redirection to a different URL using the <meta ....>
tag. Rani claims this approach could attain the same effect while
preventing the scripts from failing with the "headers already sent" error.
It still makes sense that a script which could issue a redirect has in
principle to determine whether to divert to a different URL *before* any
output is sent to the channel. admittedly this is rigid because forces a
certain design (though a sane one), it's largely undocumented and in the
end there should be a better more flexible way to do this
We obtain redirection with the 301 HTTP code and when the headers command
is called the code checks for the headers_sent flag
TCL_CMD_HEADER( Rivet_Headers )
{
...
if (globals->req->headers_printed != 0)
{
Tcl_AddObjErrorInfo(interp ,"Cannot manipulate headers - already
sent", -1);
return TCL_ERROR;
}
globals->req->headers_printed is set when the Rivet channel output
procedure is called by Tcl I/O subsystem and I wonder if there are
different ways to do it, for example making the channel implementation more
flexible about buffering. Of course this doesn't rule out the possibility
of exploiting other ways (like in Rani's proposal), but it seems to me the
HTTP protocol has to be supported in the best possible way
-- Massimo
---------- Forwarded message ----------
From: Rani Ahmed <rani...@gmail.com>
Date: Thu, Dec 11, 2014 at 8:37 PM
Subject: Hi. A suggestion.
To: Massimo Manghi <mxman...@apache.org>
Hi Massimo.
Well I suggest that you add a better redirect function/procedure other
than the *[headers* redirect $url *]* . This one always makes many people
go into the annoying error message of
*headers already sent .*
The procedur*e* will be the following, I found it on Stackoverflow. I
understand that I can put it for my own, but this little thing - I think -
can be the key that makes Rivet attractive.
*proc* http_redirect *{* url *} {*
*?>* <meta http-equiv="refresh" content="0;url='*<?=*$url;*?>*'">
*<?*
*}*
