On my receiving device, it needs to have the DCSP field set to 0xff in order to properly receive and deal with incoming UDP packets. On Linux, I can set IPPROTO_IP, IP_TOS, and everything works as expected (it being set in the header). But not so with Windows.
I tried configuring SIO_SET_QOS with the line int r = WSAIoctl( nSocket, SIO_SET_QOS, &QoS, sizeof( QoS ), 0, 0, 0, 0, 0 ); where QoS is a object of type QOS and is initialized. But it would only return -1, indicating it was not setting the service. Also, even if this did work, I don't know how I would set the DCSP to 0xff, instead of letting Windows decide its service descriptor.
I saw references to IP_DSCP_TRAFFIC_TYPE but I can't seem to figure out what it is, or its #define type, and it appears to be EOL'd.
What can I do to set the Differentiated Services Code Point field in the IP header?