Raw UDP send and receive

[Kation]

Generally, client connect to a quic server will open a udp hole, then other peer can connect to client normally.

If a client has multiple ISP network and client is behind NAT, it will use one ISP to connect server.
For better connection, I should stun a udp hole for each ISP and submit public endpoint to peers. Then peer will connect client using faster endpoint.

The point is client should stun a udp hole to keep public endpoint with a timer.

After upgrade to quic, I can't stun a udp hole after msquic owned udp port anymore.

Can we add a flag to ConnectionOpen to set connection only send/receive raw udp?
If flag set, Connection can only call DatagramSend to send packet.

[Kation]

#3270

#5627

#3550

[guhetier]

Hi @Kation, DatagramSend is for unreliable datagrams as defined in RFC 9221, it requires that the QUIC connection is already setup so datagrams are encrypted and authenticated.

There currently isn't a good way in MsQuic to access the underlying socket. For NAT punching, maybe creating a UDP socket, sending datagrams to punch the hole, then closing the socket and opening an MsQuic connection on the same local address / port would work?