mirror of
https://github.com/soypat/lneto.git
synced 2026-08-06 07:53:41 +00:00
Patricio Whittingslow
122 lines
3.0 KiB
Go
122 lines
3.0 KiB
Go
package internet
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import (
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"errors"
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"io"
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"log/slog"
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"math"
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"net"
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"github.com/soypat/lneto"
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"github.com/soypat/lneto/ethernet"
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)
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type StackEthernet struct {
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connID uint64
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handlers handlers
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mac [6]byte
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gwmac [6]byte
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mtu uint16
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}
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func (ls *StackEthernet) SetGateway6(gw [6]byte) {
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ls.gwmac = gw
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}
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func (ls *StackEthernet) Gateway6() (gw [6]byte) {
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return ls.gwmac
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}
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func (ls *StackEthernet) SetHardwareAddr6(mac [6]byte) {
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ls.mac = mac
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}
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func (ls *StackEthernet) HardwareAddr6() [6]byte {
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return ls.mac
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}
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func (ls *StackEthernet) Reset6(mac, gateway [6]byte, mtu, maxNodes int) error {
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if mtu > math.MaxUint16 || mtu < 256 {
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return errors.New("invalid MTU")
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} else if maxNodes <= 0 {
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return errZeroMaxNodesArg
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}
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ls.handlers.reset("StackEthernet", maxNodes)
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*ls = StackEthernet{
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connID: ls.connID + 1,
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handlers: ls.handlers,
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mac: mac,
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gwmac: gateway,
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mtu: uint16(mtu),
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}
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return nil
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}
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func (ls *StackEthernet) MTU() int { return int(ls.mtu) }
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func (ls *StackEthernet) ConnectionID() *uint64 { return &ls.connID }
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func (ls *StackEthernet) LocalPort() uint16 { return 0 }
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func (ls *StackEthernet) Protocol() uint64 { return 1 }
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func (ls *StackEthernet) Register(h StackNode) error {
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proto := h.Protocol()
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if proto > math.MaxUint16 || proto <= 1500 {
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return errInvalidProto
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}
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return ls.handlers.registerByProto(nodeFromStackNode(h, 0, proto, nil))
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}
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func (ls *StackEthernet) Demux(carrierData []byte, frameOffset int) (err error) {
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pkt := carrierData[frameOffset:]
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efrm, err := ethernet.NewFrame(pkt)
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if err != nil {
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return err
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}
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etype := efrm.EtherTypeOrSize()
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dstaddr := efrm.DestinationHardwareAddr()
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var vld lneto.Validator
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if !efrm.IsBroadcast() && ls.mac != *dstaddr {
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goto DROP
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}
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efrm.ValidateSize(&vld)
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if vld.HasError() {
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return vld.ErrPop()
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}
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if h, err := ls.handlers.demuxByProto(efrm.Payload(), 0, uint16(etype)); h != nil {
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return err
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}
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DROP:
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ls.handlers.info("LinkStack:drop-packet", slog.String("dsthw", net.HardwareAddr(dstaddr[:]).String()), slog.String("ethertype", efrm.EtherTypeOrSize().String()))
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return lneto.ErrPacketDrop
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}
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func (ls *StackEthernet) Encapsulate(carrierData []byte, offsetToIP, offsetToFrame int) (n int, err error) {
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mtu := ls.mtu
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dst := carrierData[offsetToFrame:]
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if len(dst) < int(mtu) {
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return 0, io.ErrShortBuffer
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}
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efrm, err := ethernet.NewFrame(dst)
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if err != nil {
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return 0, err
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}
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*efrm.DestinationHardwareAddr() = ls.gwmac
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var h *node
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// Children (IP/ARP) start at offset 14 (after ethernet header).
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// For IP: offsetToIP=14, offsetToFrame=14
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// For ARP: offsetToIP=-1, offsetToFrame=14 (but ARP ignores offsetToIP)
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// Clip carrierData to MTU to prevent writes beyond MTU limit.
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mtuLimit := offsetToFrame + int(mtu)
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h, n, err = ls.handlers.encapsulateAny(carrierData[:mtuLimit], offsetToFrame+14, offsetToFrame+14)
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if n == 0 {
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return n, err
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}
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// Found packet
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*efrm.SourceHardwareAddr() = ls.mac
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efrm.SetEtherType(ethernet.Type(h.proto))
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n += 14
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return n, err
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}
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