I'm just getting started with network programming, and have managed to get a bidirectional client script from a book or some other howto on the net connected to my av receiver.

The hardware sends out status updates to an open connection, so in this example I'm not sending anything, just listening for updates from the hardware. The hardware sends the data in hex format, so I'm not sure if that causes a problem with the <$handle> reading of the data.

When I receive an update through the connected socket, the while loop handling the socket read, seems to split the data from the network packet into 2. I added a couple of print and length statements to help illustrate my point.

Here is the output from the script when run. 
ryan@ryan-laptop:~/Documents/sockets$ perl bidir.pl 192.168.0.61 60128
[Connected to 192.168.0.61:60128]
inc data!
packet is >ISCP
<
data length is 12<
inc data!
packet is >!1MVL2D&#9618;
<
data length is 14<
^C
ryan@ryan-laptop:~/Documents/sockets$ hd dump.bidir
00000000  49 53 43 50 00 00 00 10  00 00 00 0a 01 00 00 00  |ISCP.....
+.......|
00000010  21 31 4d 56 4c 32 44 1a  0d 0a                    |!1MVL2D..
+.|
0000001a

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Now I have wireshark running at the same time, and it says only one data packet was sent, and it's data size was 26 bytes. So I'm wondering, why my socket read is splitting the 26 bytes that came from the network in 2? Here is the bidir.pl script I'm using 
#!/usr/bin/perl -w
# biclient - bidirectional forking client
use strict;
use IO::Socket;
use Data::Dumper qw(Dumper);

#open OUT, ">dump.bidir";

my ($host, $port, $kidpid, $handle, $line);
unless (@ARGV == 2) { die "usage: $0 host port" }
($host, $port) = @ARGV;
# create a tcp connection to the specified host and port
      $handle = IO::Socket::INET->new(Proto => "tcp",
                      PeerAddr => $host,
                      PeerPort => $port)
or die "can't connect to port $port on $host: $!";
$handle->autoflush(1);
# so output gets there right away
print STDERR "[Connected to $host:$port]\n";
# split the program into two processes, identical twins
die "can't fork: $!" unless defined($kidpid = fork());
if ($kidpid) {
      # parent copies the socket to standard output
      while (defined ($line = <$handle>)) {
        #print STDOUT $line;
        print "inc data!\npacket is >$line<\n";
        print "data length is " . length($line) . "<\n";
        open OUT, ">>dump.bidir";
        print OUT $line;
        close OUT;
      }
      kill("TERM" => $kidpid);    # send SIGTERM to child
}
else {
      # child copies standard input to the socket
      while (defined ($line = <STDIN>)) {
        print $handle $line;
      }
}
exit;

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In reply to Network socket noob, why is my socket read not getting all the data from a packet? by zen0n

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