Sockets provide streams of data. A message that took one call to send, may take three calls to read. Or vice versa. With TCP, you can't assume that all of your message will be available at the same time. You can only assume that it will all eventually arrive, in order, or the socket will close.

Therefore, if the boundaries of data elements are important, then you need to put markers in the data stream itself, in such a way that you know if you have the whole data element, or even the whole marker, before you start using the data. If you don't have the whole marker, wait and read again, and then see if you have the whole marker.

Again, sorry for not studying the whole code, but as someone else posted, there are some good modules that already do TCP packets for you. Another place to look is Chapter 12 of Advanced Perl Programming (by Srinivasan).