Convert hexdump to binary data

Working on analysis of network packets I needed to convert data dumped in a file to real binary form before processing them further.

I am using WireShark to capture network packets. Data were dumped WireShark’s command-line companion tshark:

tshark -n -T fields -e ip.src -e ip.dst -e data.data -r packet-data.pcap

The data output has lines with three fields, source IP, destination IP and hexdumped data.

....
192.168.0.29  192.168.0.47  10:20:10:40:00:00:04:d4							
192.168.0.29  192.168.0.47  10:20:10:40:00:00:04:d4							
192.168.0.29  192.168.0.47  00:00:00:01:00:00:04:00:10:00:00:13:00:00:00:00:00
192.168.0.29  192.168.0.47  00:00:00:01:00:00:04:00:10:00:00:13:00:00:00:00:00
....

Processing of such data is simple in perl, each line we split on tab, then decode hexdump to binary string by packing individual bytes into one string using pack.

while(<>) {
    chomp;
    my ($src_ip, $dst_ip, $hexdump) = split /\t/;
    my $data = pack 'C*', map { hex } split /:/, $hexdump;
    
    # process data -- treat it as several 4B big-endian integers
    my ($head, $len, @rest) = unpack 'N*', $data;
}