How can I distinguish between different streams

[AvatarGanymede]

Suppose that I open 3 streams on the server side. Is it possible to distinguish between them on the client side without adding extra info in the payload?

[nibanks]

Yes, you can query the ID of each stream via QUIC_PARAM_STREAM_ID.

    QUIC_UINT62 ID;
    uint32_t IDLen = sizeof(ID);
    MsQuic->GetParam(
        StreamHandle,
        QUIC_PARAM_STREAM_ID,
        &IDLen,
        &ID);

It's also worth noting that you can only query a stream's ID after it has been started; meaning just calling StreamOpen is not enough. When you receive a stream from the peer, it is already started.