validfqdn

[Bob Brewer <ipfire-devel@grantura.co.uk>]

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I am porting the old ipcop addon 'Banish' to IPFire and during testing have 
found a problem in general-functions.pl which causes validfqdn to return 1 
when testing valid and invalid ip addresses when it should return 0. 

As this is not a problem with IPCop 2 a comparison of the validfqdn section 
in IPFire's general-functions.pl shows a missing segment that checks the TLD 
can only be a-z or A-Z.

Applying the patch below to general-functions.pl corrects the problem with 
my Banish port and I haven't found any problems affecting IPFire's 
operation.

Regards

Rob

--- /tmp/general-functions.pl   2018-09-19 10:32:37.000000000 +0100
+++ /tmp/general-functions.pl.new       2018-12-12 22:13:37.394653609 +0000
@@ -666,9 +666,13 @@
 }
 
 sub validfqdn
+# modified to add addition test to confirm TL is only a-z or A-Z
+# as per ipcop rwb 12/12/18
+
 {
        my $part;
-
+        my $tld;
+     
        # Checks a fully qualified domain name against RFC1035
         my $fqdn = $_[0];
        my @parts = split (/\./, $fqdn);        # Split hostname at the '.'
@@ -689,7 +693,14 @@
                # Last character can only be a letter or a digit
                if (substr ($part, -1, 1) !~ /^[a-zA-Z0-9]*$/) {
                        return 0;}
-       }
+           # Store for additional check on TLD
+           $tld = $part;
+        } 
+
+        # TLD valid characters are a-z, A-Z
+        if ($tld !~ /^[a-zA-Z]*$/) {
+        return 0;
+        }
        return 1;
 }