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

[Adolf Belka <adolf.belka@ipfire.org>]

[-- Attachment #1: Type: text/plain, Size: 3018 bytes --]

- 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