Is there a way to block on a socket send() until we get the ack for that packet?

Question

Or do I have to implement it at the application level?

Answer 1

The whole point of using TCP is to hide that individual ACK from applications. If you need to detect every ACK, then implement your own protocol using UDP or IP. TCP is probably an overkill. Or you can go up the stack and use a protocol like HTTP as a transport.