Can be done for example by having a address allocation daemon running in user space. The socket library would create an IPC connection to the daemon and ask for

Can be done for example by having a address allocation daemon running in user space. The socket library would create an IPC connection to the daemon and ask for an address/port. The daemon would reserve the address/port and pass it back. The daemon would have to health check the applications so that it can return the addresses back to the pool in case of failure.