jrouter/router/nbp_aurp.go

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/*
Copyright 2024 Josh Deprez
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
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package router
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import (
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"context"
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"fmt"
"log"
"gitea.drjosh.dev/josh/jrouter/atalk/nbp"
"github.com/sfiera/multitalk/pkg/ddp"
)
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func (rtr *Router) HandleNBPInAURP(ctx context.Context, peer *AURPPeer, ddpkt *ddp.ExtPacket) error {
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if ddpkt.Proto != ddp.ProtoNBP {
return fmt.Errorf("invalid DDP type %d on socket 2", ddpkt.Proto)
}
nbpkt, err := nbp.Unmarshal(ddpkt.Data)
if err != nil {
return fmt.Errorf("invalid NBP packet: %v", err)
}
if nbpkt.Function != nbp.FunctionFwdReq {
// It's something else??
return fmt.Errorf("can't handle %v", nbpkt.Function)
}
if len(nbpkt.Tuples) < 1 {
return fmt.Errorf("no tuples in NBP packet")
}
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tuple := &nbpkt.Tuples[0]
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zones := rtr.ZoneTable.LookupName(tuple.Zone)
for _, z := range zones {
if z.LocalPort == nil {
continue
}
port := z.LocalPort
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log.Printf("NBP/DDP/AURP: Converting FwdReq to LkUp (%v)", tuple)
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// Convert it to a LkUp and broadcast on EtherTalk
nbpkt.Function = nbp.FunctionLkUp
nbpRaw, err := nbpkt.Marshal()
if err != nil {
return fmt.Errorf("couldn't marshal LkUp: %v", err)
}
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// "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
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if err := port.ZoneMulticast(tuple.Zone, ddpkt); err != nil {
return err
}
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// But also... if it matches us, reply directly with a LkUp-Reply of our own
outDDP, err := port.helloWorldThisIsMe(ddpkt, nbpkt.NBPID, tuple)
if err != nil || outDDP == nil {
return err
}
log.Print("NBP/DDP/AURP: Replying to BrRq with LkUp-Reply for myself")
if err := rtr.Forward(ctx, outDDP); err != nil {
return err
}
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}
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return nil
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}