When a client sends a HTTP/1.0 request to InteProxy, InteProxy tries to also send a HTTP/1.0 request to the upstream server. The idea is that this makes forwarding the response to the client easier because the entity body will not have to be changed. For instance, a HTTP/1.1 server might send the response with the "chunked" transfer encoding which the HTTP/1.0 client won't understand, requiring InteProxy to convert this properly.
Under some circumstances, InteProxy sends incorrect HTTP/1.0 requests to the upstream server. E. g. Run InteProxy with demo.cfg and send a request via InteProxy with the following wget command:
The request sent to inteproxy-demo.intevation.org currently looks like this (when sent via a https_proxy):
GET https://inteproxy-demo.intevation.org/cgi-bin/frida-wms?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetCapabilities&user=meier&password=meier HTTP/1.1
It's a HTTP/1.1 request instead of the intended HTTP/1.0 request and it's missing the required Host: header field. The server correctly responds with a 400 Bad Request.
To correct this, either the Host: header has to be set correctly or it has to be turned into a HTTP/1.0 request. The latter requires some changes to inteproxy/proxyconnection.py which always sends the absolute URL which in HTTP/1.0 is only allowed for requests to proxies.