[mapserver-dev] Re: [mapserver-users] RE: CGI returning a 502 error

[Alan Boudreault]

Even if the max cgi params is very big and that there are only few cases that 
need more, I think we could just put this dynamic rather than static. Does 
anyone have any objection about that? Else, I'm going to take care of this.

Alan

On September 23, 2010 02:22:58 am Jan Hartmann wrote:
>   Wasn't there a similar problem about the hard-coded maximum number of
> classes a few years ago? That problem was solved, if I remember
> correctly. Wouldn't it be a good idea to take that solution over to the
> number of CGI parms? The problem won't turn up often, but if it does it
> is hard to detect, and as far as I can see it's not hard to solve.
> 
> Jan
> 
> On 09/22/10 20:56, Lime, Steve D (DNR) wrote:
> > Yes, there is a preset limit on the number of parameters the MapServer
> > cgi will accept and indeed it is 100. There are two ways to work around
> > this.
> > 
> > 1) Edit the MS_MAX_CGI_PARAMS setting in cgiutil.h and recompile.
> > 2) Consider combining the requested layers calls into a single variable.
> > That is:
> > 
> > Change
> > 
> >    ...layer=layer1&layer=layer2&layer=layer3...
> > 
> > to:
> >    ...layers=layer1+layer2+layer3...
> > 
> > You should see an error message from MapServer in your web server error
> > log if you ran into this limitation...
> > 
> > Steve
> > 
> > -----Original Message-----
> > From: mapserver-users-bounces at lists.osgeo.org
> > [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of stoli
> > Sent: Tuesday, September 21, 2010 11:19 AM
> > To: mapserver-users at lists.osgeo.org
> > Subject: [mapserver-users] RE: CGI returning a 502 error
> > 
> > 
> > I do not think it is a string length limit. The IIS returns a separate
> > error for that. At least it does when you exceed the URL length limit in
> > a GET request.
> > 
> > I have been doing some tests and it looks like it might be more of a
> > limit in the number of parameters in the POST request. I can't find any
> > info regarding the maximum number of parameters that you can send in one
> > request (to an IIS server), but again, I would think that IIS would be
> > responding with a more specific error if the limit was with it.
> > 
> > Is it possible that the MapServer CGI is limited to 100 POST parameters?
> > 
> > Fawcett, David (MPCA) wrote:
> >> According to the docs, starting with MapServer 5.0, there is no limit to
> >> the number of layers in a mapfile.
> >> http://mapserver.org/introduction.html#layer-object
> >> 
> >> I am guessing that you are running into a different issue.
> >> 
> >> Have you captured the post request string and examined it to make sure
> >> that it is valid?
> >> 
> >> Are you running into a string length limit for your post request?  The
> >> URL for your post request would be limited to ~2k char for IE, but this
> >> only includes the URL to the server, not the key:value pairs.  There
> >> could be a size limit for post requests set on your Web server to help
> >> prevent DOS attacks.  I don't know where this would be set in IIS.
> >> 
> >> David.
> >> 
> >> -----Original Message-----
> >> From: mapserver-users-bounces at lists.osgeo.org
> >> [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of stoli
> >> Sent: Monday, September 20, 2010 6:18 PM
> >> To: mapserver-users at lists.osgeo.org
> >> Subject: [mapserver-users] CGI returning a 502 error
> >> 
> >> 
> >> I'm using the ms4w binaries (5.6.3) under IIS 7.
> >> 
> >> My application sends (via http POST) a lot of parameters to modify the
> >> .map
> >> file. Mostly to add features to layers that are turned off by default
> >> and then make them visible. When my parameters cause the map to show
> >> over 50 layers, the IIS returns a 502 error.
> >> 
> >> I realize that the max layers are set to 100 in the default map.h file,
> >> but
> >> like I said, I am using the compiled binaries from ms4w. Does anyone
> >> know if
> >> they change that to 50 when they compile, or should I look elsewhere to
> >> find
> >> my problem?
> >> 
> >> 
> >> 
> >> 
> >> _______________________________________________
> >> mapserver-users mailing list
> >> mapserver-users at lists.osgeo.org
> >> http://lists.osgeo.org/mailman/listinfo/mapserver-users

-- 
Alan Boudreault
Mapgears
http://www.mapgears.com
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