mirror of
https://github.com/soypat/lneto.git
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soypat
119 lines
2.6 KiB
Go
119 lines
2.6 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 StackLinkLayer struct {
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connID uint64
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handlers []node
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logger
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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 *StackLinkLayer) Reset6(mac, gateway [6]byte, mtu 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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}
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*ls = StackLinkLayer{
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connID: ls.connID + 1,
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handlers: ls.handlers[:0],
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logger: ls.logger,
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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 *StackLinkLayer) ConnectionID() *uint64 { return &ls.connID }
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func (ls *StackLinkLayer) LocalPort() uint16 { return 0 }
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func (ls *StackLinkLayer) Protocol() uint64 { return 1 }
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func (ls *StackLinkLayer) 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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eproto := uint16(proto)
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for i := range ls.handlers {
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hgot := &ls.handlers[i]
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if hgot.proto == eproto {
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return errProtoRegistered
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}
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}
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ls.handlers = append(ls.handlers, node{
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demux: h.Demux,
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encapsulate: h.Encapsulate,
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proto: eproto,
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})
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return nil
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}
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func (ls *StackLinkLayer) 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.Err()
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}
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for i := range ls.handlers {
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h := &ls.handlers[i]
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if h.proto == uint16(etype) {
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return h.demux(efrm.Payload(), 0)
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}
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}
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DROP:
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ls.info("LinkStack:drop-packet", slog.String("dsthw", net.HardwareAddr(dstaddr[:]).String()), slog.String("ethertype", efrm.EtherTypeOrSize().String()))
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return nil
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}
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func (ls *StackLinkLayer) Encapsulate(carrierData []byte, frameOffset int) (n int, err error) {
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mtu := ls.mtu
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dst := carrierData[frameOffset:]
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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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for i := range ls.handlers {
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h := &ls.handlers[i]
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n, err = h.encapsulate(dst[:mtu], 14)
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if err != nil {
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ls.error("handling", slog.String("proto", ethernet.Type(h.proto).String()), slog.String("err", err.Error()))
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continue
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}
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if n > 0 {
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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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return n + 14, nil
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}
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}
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return 0, err
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}
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