idea for making a piece of blocking code not-blocking

Hello,

I am writing to cath some ideas to make a piece of code from blocking to not-blocking. The code in question is from a hobby project where I am working where there is a esp8266 that wait for an HTTP input from my mobile phone.
The problem I am facing is that, AFAIK, I can't know when the HTTP request ends. This brought me to wait 1000 ms since the request start to make sure that every byte is received.

I am willing to have this as not-blocking because meanwhile I will move some steppers. For now i found as a temporary solution to put the steppers.run(); inside the blocking part

client = server.available();
if (client) // Incoming request
{
    while (millis() - start_connection < 1000) // blocking part
    {
        if (client.available() > 0)
        {
            request[cnt++] = client.read();
        }
        steppers.run(); // temporary solution
    }
}

Change the while into an if and let loop() run freely

what does steppers.run(); do ? hmm does it move your stepper motor ? Well how about using a timer to do that ?