josh/jrouter
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Fix BrRq-LkUp translation poisoning AARP

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This commit is contained in:
Josh Deprez 2024-05-04 16:46:44 +10:00
parent 60d1837ee8
commit 5866f091ed
Signed by: josh
SSH key fingerprint: SHA256:zZji7w1Ilh2RuUpbQcqkLPrqmRwpiCSycbF2EfKm6Kw
1 changed files with 48 additions and 48 deletions
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96
router/nbp.go
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@ -27,51 +27,6 @@ import (
"github.com/sfiera/multitalk/pkg/ddp"
)
func (rtr *Router) handleNBPFwdReq(ctx context.Context, ddpkt *ddp.ExtPacket, nbpkt *nbp.Packet) error {
// A FwdReq was addressed to us. That means a remote router thinks the
// zone is available on one or more of our local networks.
// There must be 1!
tuple := &nbpkt.Tuples[0]
for _, outPort := range rtr.Ports {
if !slices.Contains(outPort.AvailableZones, tuple.Zone) {
continue
}
log.Printf("NBP: Converting FwdReq to LkUp (%v)", tuple)
// Convert it to a LkUp and broadcast on the corresponding port
nbpkt.Function = nbp.FunctionLkUp
nbpRaw, err := nbpkt.Marshal()
if err != nil {
return fmt.Errorf("couldn't marshal LkUp: %v", err)
}
// Inside AppleTalk SE, pp 8-20:
// "If the destination network is extended, however, the router must also
// change the destination network number to $0000, so that the packet is
// received by all nodes on the network (within the correct zone multicast
// address)."
ddpkt.DstNet = 0x0000
ddpkt.DstNode = 0xFF // Broadcast node address within the dest network
ddpkt.Data = nbpRaw
if err := outPort.ZoneMulticast(tuple.Zone, ddpkt); err != nil {
return err
}
// But also... if it matches us, reply directly with a LkUp-Reply of our own
outDDP, err := outPort.helloWorldThisIsMe(nbpkt.NBPID, tuple)
if err != nil || outDDP == nil {
return err
}
if err := rtr.Output(ctx, outDDP); err != nil {
return err
}
}
return nil
}
func (port *EtherTalkPort) HandleNBP(ctx context.Context, ddpkt *ddp.ExtPacket) error {
if ddpkt.Proto != ddp.ProtoNBP {
return fmt.Errorf("invalid DDP type %d on socket 2", ddpkt.Proto)
@ -141,9 +96,9 @@ func (port *EtherTalkPort) handleNBPBrRq(ctx context.Context, ddpkt *ddp.ExtPack
ExtHeader: ddp.ExtHeader{
Size: atalk.DDPExtHeaderSize + uint16(len(nbpRaw)),
Cksum: 0,
SrcNet: ddpkt.SrcNet,
SrcNode: ddpkt.SrcNode,
SrcSocket: ddpkt.SrcSocket,
SrcNet: port.MyAddr.Network,
SrcNode: port.MyAddr.Node,
SrcSocket: 2,
DstNet: 0x0000, // Local network broadcast
DstNode: 0xFF, // Broadcast node address within the dest network
DstSocket: 2,
@ -207,6 +162,51 @@ func (port *EtherTalkPort) handleNBPBrRq(ctx context.Context, ddpkt *ddp.ExtPack
return nil
}
func (rtr *Router) handleNBPFwdReq(ctx context.Context, ddpkt *ddp.ExtPacket, nbpkt *nbp.Packet) error {
// A FwdReq was addressed to us. That means a remote router thinks the
// zone is available on one or more of our local networks.
// There must be 1!
tuple := &nbpkt.Tuples[0]
for _, outPort := range rtr.Ports {
if !slices.Contains(outPort.AvailableZones, tuple.Zone) {
continue
}
log.Printf("NBP: Converting FwdReq to LkUp (%v)", tuple)
// Convert it to a LkUp and broadcast on the corresponding port
nbpkt.Function = nbp.FunctionLkUp
nbpRaw, err := nbpkt.Marshal()
if err != nil {
return fmt.Errorf("couldn't marshal LkUp: %v", err)
}
// Inside AppleTalk SE, pp 8-20:
// "If the destination network is extended, however, the router must also
// change the destination network number to $0000, so that the packet is
// received by all nodes on the network (within the correct zone multicast
// address)."
ddpkt.DstNet = 0x0000
ddpkt.DstNode = 0xFF // Broadcast node address within the dest network
ddpkt.Data = nbpRaw
if err := outPort.ZoneMulticast(tuple.Zone, ddpkt); err != nil {
return err
}
// But also... if it matches us, reply directly with a LkUp-Reply of our own
outDDP, err := outPort.helloWorldThisIsMe(nbpkt.NBPID, tuple)
if err != nil || outDDP == nil {
return err
}
if err := rtr.Output(ctx, outDDP); err != nil {
return err
}
}
return nil
}
// Returns an NBP LkUp-Reply for the router itself, with the address from this port.
func (port *EtherTalkPort) helloWorldThisIsMe(nbpID uint8, tuple *nbp.Tuple) (*ddp.ExtPacket, error) {
if tuple.Object != "jrouter" && tuple.Object != "=" {