Greetings to all,

What sort on checks do you need to perform to ensure that someone has not altered the contents of your html form and then submitting the altered form to the destinated perl script on your server?

I suspect this must be something pretty trivial to do but my search on Google hasn't yielded anything specific.

Hope I've made the question clear...

Thanks in anticipation :)

Updated: Is the code below effective in disallowng submission of an altered form?

# source: fd_board.cgi (with modifications)
sub check_url {
   my @referers = (www.hello.com. hello.com);

   if ( (!$ENV{'HTTP_REFERER'}) ||
        (!$ENV{'CONTENT_LENGTH'}) ||
        (!$ENV{'HTTP_ACCEPT'}) ||
        (!$ENV{'HTTP_USER_AGENT'})) {
         &error('bad_headers');
   }

   my $check_referer = 0;

   foreach my $referer (@referers) {
    if ($ENV{'HTTP_REFERER'} =~ m|https?://([^/]*)$referer|i) {
        $check_referer = 1;
        last;
    }
   }

   if ($check_referer != 1) {
    &error('bad_referer')
   }
}

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janitored by ybiC: Retitle from "CGI script invocation..." for better searching

In reply to CGI form data validation by kiat

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