pub fn dgram_header(client: SocketAddr, backend: SocketAddr) -> Vec<u8> ⓘExpand description
Build the PPv2 DGRAM header bytes for a datagram whose real client source is
client and whose backend destination is backend.
When the two addresses are mixed-family (one v4, one v6 — which the UDP
datapath never produces, since the connected upstream socket matches the
backend family) this falls back to an AF_UNSPEC / UNSPEC header with a
zero-length address block, exactly as the TCP serializer does. The backend
must then treat the connection as un-proxied, per the spec’s UNSPEC rule.