package POE::Filter::LittleEndian;

use strict;
use warnings;
use Carp qw{ croak carp cluck };

use constant FRAMING_BUFFER => 0;
use constant EXPECTED_SIZE => 1;
use constant EVENT_CODE => 2;

#---------------------------------------------------------------------
+---------

sub new {
    my $type = shift;
    if (@_) { carp "POE::Filter::LittleEndian does not support any arg
+uments!\n" }

  my $self =
    bless [ '',
            undef,
                        undef,
          ], $type;

  $self;
}

#---------------------------------------------------------------------
+---------

sub get {
  my ($self, $stream) = @_;
  my @blocks;
  $self->[FRAMING_BUFFER] .= join '', @{$stream};

    # we know what to expect, size wise
    if ( defined $self -> [EXPECTED_SIZE] ) {

        # if the length of the buffer is less than we had hoped for, e
+xit.
        last if (length $self -> [FRAMING_BUFFER] < $self -> [EXPECTED
+_SIZE]);

        # read in as much as we can
        my $chunk = substr($self -> [FRAMING_BUFFER], 0, $self -> [EXP
+ECTED_SIZE]);
        # and then zap it, because we've read it.
        substr($self -> [FRAMING_BUFFER], 0, $self -> [EXPECTED_SIZE])
+ = '';
        # and now we need another LENGTH block so we zap this one...
        undef $self -> [EXPECTED_SIZE];

        # and return to caller.
        push @blocks, $chunk;
    }
    # we dont know what to expect, this is a new packet.
    else {
        my $little_e = $self -> [FRAMING_BUFFER];
        my ($length, $event) = unpack 'vv', $little_e;
        my $body;
        # tell our hackers what event they had.
        $self -> [EVENT_CODE] = $event;
        # lop off the event code and the length, the hacker has it in 
+the object.
        if ($length and (length $little_e >= 4 + $length)) {
            $body = substr($little_e, 4, $length);
        }
        $self -> [FRAMING_BUFFER] = $body;
        $self -> [EXPECTED_SIZE] = $length;
    }

    return \@blocks;
}

#---------------------------------------------------------------------
+---------
# 2001-07-27 RCC: The get_one() variant of get() allows Wheel::Xyz to
# retrieve one filtered block at a time.  This is necessary for filter
# changing and proper input flow control.

sub get_one_start {
  my ($self, $stream) = @_;
  $self->[FRAMING_BUFFER] .= join '', @$stream;
}

sub get_one {
    my $self = shift;

    if    ( defined $self -> [EXPECTED_SIZE] ) {

        return [ ] if length($self->[FRAMING_BUFFER]) < $self->[EXPECT
+ED_SIZE];

        my $block = substr($self->[FRAMING_BUFFER], 0, $self->[EXPECTE
+D_SIZE]);
        substr($self->[FRAMING_BUFFER], 0, $self->[EXPECTED_SIZE]) = '
+';
        undef $self->[EXPECTED_SIZE];

        return [ $block ];
    }
    else {
        my $little_e = $self -> [FRAMING_BUFFER];
        my ($length, $event) = unpack 'vv', $little_e;
        return [ ] unless ($length and $event);
        my $body;
        
        $self -> [EXPECTED_SIZE] = $length;

        if ($length and (length $little_e >= 4 + $length)) {
            $body = substr($little_e, 4, $length);
        }
        $self -> [EVENT_CODE] = $event;
        $self -> [FRAMING_BUFFER] = $body;
        return [ ] if length($self->[FRAMING_BUFFER]) < $self->[EXPECT
+ED_SIZE];

        my $block = substr($self->[FRAMING_BUFFER], 0, $self->[EXPECTE
+D_SIZE]);
        substr($self->[FRAMING_BUFFER], 0, $self->[EXPECTED_SIZE]) = '
+';
        undef $self->[EXPECTED_SIZE];

        return [ $block ];
    }
    return [ ]; # not sure why we'd get here, but best to be safe...
}

#---------------------------------------------------------------------
+---------

sub put {
    my ($self, $blocks) = (@_);
    return $blocks;
}

#---------------------------------------------------------------------
+---------

sub get_pending {
    my $self = shift;
    return undef unless length $self->[FRAMING_BUFFER];
    return [ $self->[FRAMING_BUFFER] ];
}

######################################################################
+#########
1;

__END__
[download]

Basically, I've incorporated some of the methods from MP3::Napster, which also uses the protocol, and the aforementioned POE filter.

I think what's happening is I am inadvertently clobbering the [EXPECTED_SIZE] attribute of the object. I feel like I have a very good understanding of the code, and see what it's doing, but I cant seem to figure out where I am messing it up.

I have this great 'hexdump' code which converter graciously gave me, and I can see that in the middle of the next messages, there are 'overflows' of one message into the other with the little-endian bytes at the front.

I'd really appreciate it if somebody <!- except tilly of course -> could take a look at this for me, and see if there's something that doesnt add up.

--
Laziness, Impatience, Hubris, and Generosity.