How to read data from socket, until client stopped send?

I have some problem.
I have client and server. Client connect with server over TCP.
Then, client send some data (separated by chunks), I don't know what is the length of data (TLS handshake). But I know that client send some data with fixed length, and then stop, until not received some response, then he send data with fixed length again.

I need read all chunks, until client stopped send (because so many chunks). How to do that ?

I have only one idea, it's timeout. Read data in loop and set timeout between iterate. If timeout is ended, then data complete collected.

Perhaps there is a more elegant solution?

Based on the information in your comments, you're doing this wrong. The correct way to write an HTTPS proxy is to read the CONNECT line, make the upstream connection, send the appropriate response back o the client, and then if successful start copying bytes in both directions simultaneously. You're not in the least concerned with packets or read sizes, and you should certainly not make any attempt to 'collect' packets before retransmission, as that will just add latency to the system.

You can accomplish this either by starting two threads per connection, one in each direction, or via non-blocking sockets and select()/poll()/epoll(), or whatever that looks like in Go.

BUT I have no idea why you're doing this at all. There are plenty of open-source HTTP proxies already in existence, and as you're dealing with HTTPS there is no value you can possibly add to them. Your claim about 'business logic' is meaningless, or at least unimplementable.