Example UPnP message found in the wild:

HTTP/1.1 200 OK
CACHE-CONTROL: max-age=1800
DATE: Tue, 18 Aug 2020 22:30:55 GMT
EXT:
LOCATION: http://192.168.1.1:60000/62177d51/gatedesc.xml
SERVER: Unspecified, UPnP/1.0, SoftAtHome
ST: upnp:rootdevice
USN: uuid:62177d51-6ebe-4d59-9e8d-59cc417d3f9c::upnp:rootdevice

changed the title Fixes for HttpLexer HttpLexer: support for empty HTTP headers