| Subject: | Problem with indefinite BER-lengths |
Hi.
I've found a tiny problem in theConvert::BER module. Indefinite length
of BER-strings are not handled 100% correct. Please find attached a
Perl-script pointing out the problem. The problem shown in the script
is, that the indefinite-length terminator 0x0000 is not cut off
completely and
I have a remaining 0x00 byte at the end of my data. The consequence is
that the Decoder thinks that there are still some remaining bytes in the
buffer to be decoded, but there should not be any left.
Hope I submitted enough information to point out the problem.
Best Regards.
Martin.
| Subject: | test_convert_ber_indefinite_lengths.pl |
#!/usr/bin/perl -w
use strict;
use Convert::BER;
print <<EOT;
Structure of the BER-string with indefinite length
30 12
80 08 02181060414710f2
a2 80 80008100
0000
EOT
my ($string1, $string2, $ber, $retval);
my $ber_indefinite = pack("H*", '3012800802181060414710f2a280800081000000');
my $ber_definite = pack("H*", '3010800802181060414710f2a20480008100');
print "========== definite length =============\n";
$ber = new Convert::BER($ber_definite);
$ber->hexdump();
# This decoding works fine
$retval = $ber->decode(
SEQUENCE => [
[ STRING => 0x80 ] => \$string1,
[ STRING => 0xA2 ] => \$string2,
],
);
unless (defined($retval)) {
print $ber->error();
}
print "string1: <".unpack("H*",$string1).">\n" if (defined($string1));
print "string2: <".unpack("H*",$string2).">\n" if (defined($string2));
print "========== indefinite length =============\n";
$ber = new Convert::BER($ber_indefinite);
$ber->hexdump();
# This decoding here struggles with the indefinite length of the 0xA2 tag.
# The problem is that the outcome in $string2 contains one 00-byte at the
# end which is part of the terminator. This means instead of 80008100 I
# get 8000810000.
$retval = $ber->decode(
SEQUENCE => [
[ STRING => 0x80 ] => \$string1,
[ STRING => 0xA2 ] => \$string2,
],
);
unless (defined($retval)) {
print $ber->error();
}
print "string1: <".unpack("H*",$string1).">\n" if (defined($string1));
print "string2: <".unpack("H*",$string2).">\n" if (defined($string2));