Follow redirect of a captive portal with NodeMCU 0.9

Question

What am I doing?

Trying to connect to a free wifi with a Nodemcu 0.9.

What I have already done?

Connecting and loading a test page in order to be redirected to the login page

Connection code:

 const char* ssid = "polimi";

  Serial.println("Attempting to connect");
  WiFi.begin(ssid);
  //Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

Detection of captive portal

  String host = "clients3.google.com";
  String site = "/generate_204";

  Serial.print("Connecting to ");
  Serial.println(host);

  WiFiClient client;
  const int httpPort = 80;
  if (!client.connect(host, httpPort)) {
    Serial.println("connection failed");
    return;
  }

  // We now create a URI for the request
  Serial.print("Requesting URL: ");
  Serial.println(site);

  client.print(String("GET ") + site + " HTTP/1.1\r\n" +
    "Host: " + host + "\r\n" + 
    "Connection: close\r\n\r\n");  
  delay(500);

  // Read all the lines of the reply from server and print them to Serial
  while(client.available()){
    String line = client.readStringUntil('\r');
    Serial.print(line);
  }
  Serial.println("");

  Serial.println("###Connection closed###");

What am I obtaining?

Nothing, but I wanted to obtain the html strings of the captive portal

What I'd Like

Find a way to follow the redirect and finally send a POST with my credential.