Client message:
=========================
       BWIDTH q4s://www.example.com Q4S/1.0
       User-Agent: q4s-ua-experimental-1.0
       Session-Id: 53655765
       Sequence-Number: 0
       Content-Type: text
       Content-Length: XXXX
       Measurements: l=22, j=10, pl=0.00, bw=3000

       VkZaU1FrNVZNVlZSV0doT1ZrZ (to complete up to "max-content-
                                 length" bytes UDP payload length)
=========================