don't decode MAD on cards without it

diff --git a/mifare-mad.pl b/mifare-mad.pl
index 2adb705..18e4b6b 100755 (executable)
--- a/mifare-mad.pl
+++ b/mifare-mad.pl
@@ -66,6 +66,8 @@ my $card = <>;
 die "expected 4096 bytes, got ",length($card), " bytes\n"
        unless length $card == 4096;
 
+my ( $ADV, $MA, $DA );
+
 foreach my $i ( 0 .. 15 ) {
 
        my $pos = 0x40 * $i;
@@ -78,12 +80,15 @@ foreach my $i ( 0 .. 15 ) {
                        ;
                # General purpose byte (GPB)
                my $gdp = ord(substr($card,0x39,1));
-               printf "ADV (MAD version code): %d\n", $gdp & 0b00000011;
-               printf "MA (multiapplication): %s\n",  $gdp & 0b01000000 ? 'yes' : 'monoaplication';
-               printf "DA (MAD available): %s\n",     $gdp & 0b10000000 ? 'yes' : 'no';
+               $ADV = $gdp & 0b00000011;
+               $MA  = $gdp & 0b01000000;
+               $DA  = $gdp & 0b10000000;
+               printf "ADV (MAD version code): %d\n", $ADV;
+               printf "MA (multiapplication): %s\n",  $MA ? 'yes' : 'monoaplication';
+               printf "DA (MAD available): %s\n",     $DA ? 'yes' : 'no';
 
                printf "Info byte (publisher sector): %x\n", ord(substr($card,0x11,1));
-       } else {
+       } elsif ( $DA ) {
                my $mad_offset = 0x10 + ( $i * 2 );
                my $v = unpack('v',(substr($card, $mad_offset, 2)));
                my $cluster_id = unpack('HH', (( $v & 0xff00 ) >> 8) );
@@ -116,6 +121,8 @@ foreach my $i ( 0 .. 15 ) {
                        printf "Card number: %s\n", unpack('h*',substr($card,$pos + 0x04,6));
                }
 
+       } else {
+               printf "# sector %-2d\n", $i;
        }
 
        my $c1 = ( ord(substr($card,$pos+0x37,1)) & 0xf0 ) >> 4;