HTTP Data chunks over multiple packets?

Question

What is the correct way for a HTTP server to send data over multiple packets?

For example I want to transfer a file, the first packet I send is:

HTTP/1.1 200 OK
Content-type: application/force-download
Content-Type: application/download
Content-Type: application/octet-stream
Content-Description: File Transfer
Content-disposition: attachment; filename=test.dat
Content-Transfer-Encoding: chunked

400
<first 1024 bytes here>

400
<next 1024 bytes here>

400
<next 1024 bytes here>

Now I need to make a new packet, if I just send:

400
<next 1024 bytes here>

All the clients close there connections on me and the files are cut short.

What headers do I put in a second packet to continue on with the data stream?

Answer 1

My lack-of-rep appears to not allow me to comment on the question, just answer it, so I'm assuming that something like "you're trying to implement HTTP 1.1 on the web server of an embedded device that has a packet-oriented network stack instead of a stream-oriented one" is true, or you wouldn't be talking about packets. (If you ARE talking about chunks, see other answers.)

Given that -- use sockets if you can; you shouldn't have to think in packets. There's probably a wrapper somewhere for your network stack. If there isn't, write one that doesn't nuke your performance too badly.

If you can't, for whatever reason -- you're probably blowing out the size of the first packet. Your MTU's probably something like 1500 or 1492 (or smaller), and you have + 5 + 1024 + 5 + 1024 + 5 + 1024 bytes listed "in your first packet." Your network stack may suck enough that it's not giving you error codes, or your code may not be checking them -- or it may be doing something else equally useless.