Re: [PATCH] logo.cgi: Fix for bug13795 - captive portal not displaying uploaded logo

[Michael Tremer <michael.tremer@ipfire.org>]

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Hello Adolf,

I assume this might not fully fix the problem since we don’t know for certain if the uploaded file is a JPEG file.

I believe this is why have chosen something very generic instead of a specific image type. I assume that we would have to run something to check the correct MIME type of the file before we can send anything.

  https://metacpan.org/release/FITZNER/File-LibMagic-0.96/view/LibMagic.pm

This could do the job.

-Michael

> On 6 Jan 2025, at 16:21, Adolf Belka <adolf.belka(a)ipfire.org> wrote:
> 
> - Something changed in some package in CU188 that means that the existing method of
>   printing the content type to the browser no longer worked.
> - I tested it in some stand alone code and even if using text/txt for the content-type
>   print statement the File::Copy::copy then resulted in an Internal Server Error with
>   the same message as with the image file which was "malformed header from script
>   'logo.cgi': Bad header:".
> - I tested it with text, html, image and application. In all cases the error message
>   about a bad header was provided.
> - Did some searching and found an alternative way to explicitly print the header info
>   which is what I have used in this patch change.
> - With this approach, in the stand alone code, I was able to get an image, html code or
>   text shown in the browser correctly and without any error message.
> - I then used this new method in the logo.cgi code as submitted here and tested the
>   change in my vm testbed and the image was shown in the captive portal correctly.
> - So this change fixes the problem with the logo not being shown but I have been unable
>   to identify what changed to stop the method that worked prior to CU188 from working
>   any more.
> 
> Fixes: Bug13795
> Tested-by: Adolf Belka <adolf.belka(a)ipfire.org>
> Signed-off-by: Adolf Belka <adolf.belka(a)ipfire.org>
> ---
> html/cgi-bin/captive/logo.cgi | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/html/cgi-bin/captive/logo.cgi b/html/cgi-bin/captive/logo.cgi
> index 8f292b171..09fe784b8 100644
> --- a/html/cgi-bin/captive/logo.cgi
> +++ b/html/cgi-bin/captive/logo.cgi
> @@ -2,9 +2,9 @@
> ###############################################################################
> #                                                                             #
> # IPFire.org - A linux based firewall                                         #
> -# Copyright (C) 2016  Alexander Marx alexander.marx(a)ipfire.org                #
> +# Copyright (C) 2016-2024  IPFire Team  <info(a)ipfire.org>                     #
> #                                                                             #
> -# This program is free software you can redistribute it and/or modify         #
> +# This program is free software: you can redistribute it and/or modify        #
> # it under the terms of the GNU General Public License as published by        #
> # the Free Software Foundation, either version 3 of the License, or           #
> # (at your option) any later version.                                         #
> @@ -29,6 +29,7 @@ use File::Copy;
> 
> require '/var/ipfire/general-functions.pl';
> 
> +my $q = new CGI;
> my $logo = "${General::swroot}/captive/logo.dat";
> 
> # Send 404 if logo was not uploaded and exit
> @@ -37,8 +38,8 @@ if (!-e $logo) {
> exit(0);
> }
> 
> -print "Content-Type: application/octet-stream\n\n";
> -
> # Send image data
> +print $q->header(-type=>"image/jpeg");
> +binmode STDOUT;
> File::Copy::copy $logo, \*STDOUT;
> exit(0);
> -- 
> 2.47.1
>