Enum FrameAction 

pub enum FrameAction {
    TcpSyn {
        src: SocketAddr,
        dst: SocketAddr,
    },
    UdpRelay {
        src: SocketAddr,
        dst: SocketAddr,
    },
    Dns,
    Passthrough,
}

Result of classifying a guest ethernet frame before smoltcp processes it.

Pre-inspection allows the poll loop to:

• Create TCP sockets before smoltcp sees a SYN (preventing auto-RST).
• Handle non-DNS UDP outside smoltcp (smoltcp lacks wildcard port binding).
• Route DNS queries to the interception handler.

Variants

TcpSyn

TCP SYN to a new destination — create a smoltcp socket before letting smoltcp process the frame.

Fields

src: SocketAddr

dst: SocketAddr

UdpRelay

Non-DNS UDP datagram — handle entirely outside smoltcp via the UDP relay.

Fields

src: SocketAddr

dst: SocketAddr

Dns

DNS query (UDP to port 53) — let smoltcp’s bound UDP socket handle it.

Passthrough

Everything else (ARP, NDP, ICMP, TCP data/ACK/FIN, etc.) — let smoltcp process normally.