TCP framing techniques

What is the proper way or technique in framing with TCP?

I have created a simple framer in my node.js server that frames each message as they come-in where the 1st byte is the packet size.

One problem though: What if a user purposely sends an invalid packet.

Something like:

0A 00 03 04 05

We can tell that this is a broken packet, 0A is the size but we can see that the actual size is only 05.

How can we prevent such attacks?