huge tap/bridge overhaul; udp node; dhcp node; DHCP example

internet/stack-udpport.go

@@ -0,0 +1,78 @@
+package internet
+
+import (
+	"log/slog"
+	"net"
+
+	"github.com/soypat/lneto"
+	"github.com/soypat/lneto/udp"
+)
+
+type StackUDPPort struct {
+	h      node
+	vld    lneto.Validator
+	rmport uint16
+}
+
+func (sudp *StackUDPPort) SetStackNode(node StackNode, rmport uint16) {
+	sudp.h = nodeFromStackNode(node, node.LocalPort(), node.Protocol())
+	sudp.rmport = rmport
+}
+
+func (sudp *StackUDPPort) Protocol() uint64 { return uint64(lneto.IPProtoUDP) }
+
+func (sudp *StackUDPPort) LocalPort() uint16 { return sudp.h.port }
+
+func (sudp *StackUDPPort) ConnectionID() *uint64 { return sudp.h.connID }
+
+func (sudp *StackUDPPort) Demux(carrierData []byte, frameOffset int) error {
+	if checkNode(&sudp.h) {
+		sudp.h.destroy()
+		return net.ErrClosed
+	}
+	ufrm, err := udp.NewFrame(carrierData[frameOffset:])
+	if err != nil {
+		return err
+	}
+	ufrm.ValidateSize(&sudp.vld)
+	if sudp.vld.HasError() {
+		return sudp.vld.ErrPop()
+	}
+	dst := ufrm.DestinationPort()
+	if dst != sudp.h.port {
+		return nil // Not meant for us.
+	}
+
+	src := ufrm.SourcePort()
+	if sudp.rmport != 0 && src != sudp.rmport {
+		return nil // Not from our target remote port.
+	}
+	err = sudp.h.demux(ufrm.Payload(), 8)
+	if err != nil {
+		if checkNodeErr(&sudp.h, err) {
+			sudp.h.destroy()
+		}
+		slog.Error("stackudp:demux", slog.String("err", err.Error()))
+	}
+	return err
+}
+
+func (sudp *StackUDPPort) Encapsulate(carrierData []byte, frameOffset int) (int, error) {
+	if checkNode(&sudp.h) {
+		sudp.h.destroy()
+		return 0, net.ErrClosed
+	}
+	ufrm, err := udp.NewFrame(carrierData[frameOffset:])
+	if err != nil {
+		return 0, err
+	}
+	ufrm.SetSourcePort(sudp.h.port)
+	ufrm.SetDestinationPort(sudp.rmport)
+	n, err := sudp.h.encapsulate(carrierData[frameOffset:], 8)
+	if err != nil {
+		slog.Error("stackudp:demux", slog.String("err", err.Error()))
+	}
+	ufrm.SetLength(8 + uint16(n))
+	// UDP CRC left to IP layer.
+	return n, err
+}