Add AEP, add AARP assigned chan

aarp.go

@@ -34,9 +34,10 @@ type AARPMachine struct {
 	// The Run goroutine is responsible for all writes to myAddr.Proto and
 	// probes, so this mutex is not used to enforce a single writer, only
 	// consistent reads
-	mu     sync.RWMutex
+	mu         sync.RWMutex
-	myAddr aarp.AddrPair
+	myAddr     aarp.AddrPair
-	probes int
+	probes     int
+	assignedCh chan struct{}
 }
 
 // NewAARPMachine creates a new AARPMachine.
@@ -48,6 +49,7 @@ func NewAARPMachine(cfg *config, pcapHandle *pcap.Handle, myHWAddr ethernet.Addr
 		myAddr: aarp.AddrPair{
 			Hardware: myHWAddr,
 		},
+		assignedCh: make(chan struct{}),
 	}
 }
 
@@ -59,6 +61,11 @@ func (a *AARPMachine) Address() (aarp.AddrPair, bool) {
 	return a.myAddr, a.assigned()
 }
 
+// Assigned returns a channel that is closed when the local address is valid.
+func (a *AARPMachine) Assigned() <-chan struct{} {
+	return a.assignedCh
+}
+
 // Run executes the machine.
 func (a *AARPMachine) Run(ctx context.Context, incomingCh <-chan *ethertalk.Packet) error {
 	// Initialise our DDP address with a preferred address (first network.1)
@@ -80,6 +87,7 @@ func (a *AARPMachine) Run(ctx context.Context, incomingCh <-chan *ethertalk.Pack
 
 		case <-ticker.C:
 			if a.assigned() {
+				close(a.assignedCh)
 				// No need to keep the ticker running if assigned
 				ticker.Stop()
 				continue
@@ -158,7 +166,7 @@ func (a *AARPMachine) Run(ctx context.Context, incomingCh <-chan *ethertalk.Pack
 // If the address is in the cache (AMT) and is still valid, that is used.
 // Otherwise, the address is resolved using AARP.
 func (a *AARPMachine) Resolve(ctx context.Context, ddpAddr ddp.Addr) (ethernet.Addr, error) {
-	result, waitCh := a.addressMappingTable.lookupOrWait(ddpAddr)
+	result, waitCh := a.lookupOrWait(ddpAddr)
 	if waitCh == nil {
 		return result, nil
 	}
@@ -179,7 +187,7 @@ func (a *AARPMachine) Resolve(ctx context.Context, ddpAddr ddp.Addr) (ethernet.A
 			return ethernet.Addr{}, ctx.Err()
 
 		case <-waitCh:
-			result, waitCh = a.addressMappingTable.lookupOrWait(ddpAddr)
+			result, waitCh = a.lookupOrWait(ddpAddr)
 			if waitCh == nil {
 				return result, nil
 			}

atalk/aep/aep.go

@@ -0,0 +1,38 @@
+package aep
+
+import "fmt"
+
+type Function uint8
+
+const (
+	EchoRequest Function = 1
+	EchoReply   Function = 2
+)
+
+// Packet represents an AEP packet.
+type Packet struct {
+	Function Function
+	Data     []byte
+}
+
+// Marshal marshals an AEP packet.
+func (p *Packet) Marshal() ([]byte, error) {
+	if p.Function < 1 || p.Function > 2 {
+		return nil, fmt.Errorf("invalid AEP function %d", p.Function)
+	}
+	if len(p.Data) == 0 {
+		return nil, fmt.Errorf("empty AEP packet")
+	}
+	return append([]byte{byte(p.Function)}, p.Data...), nil
+}
+
+// Unmarshal unmarshals an AEP packet.
+func Unmarshal(data []byte) (*Packet, error) {
+	if len(data) < 1 {
+		return nil, fmt.Errorf("insufficient input length %d for AEP packet", len(data))
+	}
+	return &Packet{
+		Function: Function(data[0]),
+		Data:     data[1:],
+	}, nil
+}

main.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"errors"
 	"flag"
+	"fmt"
 	"io"
 	"log"
 	"math/rand/v2"
@@ -31,6 +32,7 @@ import (
 	"time"
 
 	"gitea.drjosh.dev/josh/jrouter/atalk"
+	"gitea.drjosh.dev/josh/jrouter/atalk/aep"
 	"gitea.drjosh.dev/josh/jrouter/aurp"
 	"github.com/google/gopacket/pcap"
 	"github.com/sfiera/multitalk/pkg/ddp"
@@ -244,6 +246,12 @@ func main() {
 				switch ddpkt.DstSocket {
 				case 1: // The RTMP socket
 					rtmpCh <- &ddpkt
+
+				case 4: // The AEP socket
+					if err := handleAEP(pcapHandle, myHWAddr, ethFrame.Src, &ddpkt); err != nil {
+						log.Printf("AEP: Couldn't handle: %v", err)
+					}
+
 				default:
 					log.Printf("DDP: No handler for socket %d", ddpkt.DstSocket)
 				}
@@ -327,6 +335,45 @@ func main() {
 	}
 }
 
+func handleAEP(pcapHandle *pcap.Handle, src, dst ethernet.Addr, ddpkt *ddp.ExtPacket) error {
+	if ddpkt.Proto != ddp.ProtoAEP {
+		return fmt.Errorf("invalid DDP type %d on socket 4", ddpkt.Proto)
+	}
+	ep, err := aep.Unmarshal(ddpkt.Data)
+	if err != nil {
+		return err
+	}
+	switch ep.Function {
+	case aep.EchoReply:
+		// we didn't send a request? I don't think?
+		// we shouldn't be sending them from this socket
+		return fmt.Errorf("echo reply received at socket 4 why?")
+
+	case aep.EchoRequest:
+		// Uno Reverso the packet
+		// "The client can send the Echo Request datagram through any socket
+		// the client has open, and the Echo Reply will come back to this socket."
+		ddpkt.DstNet, ddpkt.SrcNet = ddpkt.SrcNet, ddpkt.DstNet
+		ddpkt.DstNode, ddpkt.SrcNode = ddpkt.SrcNode, ddpkt.DstNode
+		ddpkt.DstSocket, ddpkt.SrcSocket = ddpkt.SrcSocket, ddpkt.DstSocket
+		ddpkt.Data[0] = byte(aep.EchoReply)
+
+		ethFrame, err := ethertalk.AppleTalk(src, *ddpkt)
+		if err != nil {
+			return err
+		}
+		ethFrame.Dst = dst
+		ethFrameRaw, err := ethertalk.Marshal(*ethFrame)
+		if err != nil {
+			return err
+		}
+		return pcapHandle.WritePacketData(ethFrameRaw)
+
+	default:
+		return fmt.Errorf("invalid AEP function %d", ep.Function)
+	}
+}
+
 // Hashable net.UDPAddr
 type udpAddr struct {
 	ipv4 [4]byte

rtmp.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"log"
 	"time"
 
@@ -19,7 +20,15 @@ type RTMPMachine struct {
 	pcapHandle *pcap.Handle
 }
 
+// Run executes the machine.
 func (m *RTMPMachine) Run(ctx context.Context, incomingCh <-chan *ddp.ExtPacket) error {
+	// Await local address assignment before doing anything
+	<-m.aarp.Assigned()
+	myAddr, ok := m.aarp.Address()
+	if !ok {
+		return fmt.Errorf("AARP machine closed Assigned channel but Address is not valid")
+	}
+
 	bcastTicker := time.NewTicker(10 * time.Second)
 	defer bcastTicker.Stop()
 
@@ -30,10 +39,6 @@ func (m *RTMPMachine) Run(ctx context.Context, incomingCh <-chan *ddp.ExtPacket)
 
 		case <-bcastTicker.C:
 			// Broadcast an RTMP Data
-			myAddr, ok := m.aarp.Address()
-			if !ok {
-				continue
-			}
 
 			dataPkt := m.dataPacket(myAddr.Proto)
 
@@ -71,10 +76,6 @@ func (m *RTMPMachine) Run(ctx context.Context, incomingCh <-chan *ddp.ExtPacket)
 					log.Printf("RTMP: Couldn't unmarshal Request packet: %v", err)
 				}
 
-				myAddr, ok := m.aarp.Address()
-				if !ok {
-					continue
-				}
 				// should be in the cache...
 				theirHWAddr, err := m.aarp.Resolve(ctx, ddp.Addr{Network: pkt.SrcNet, Node: pkt.SrcNode})
 				if err != nil {
@@ -151,6 +152,8 @@ func (m *RTMPMachine) Run(ctx context.Context, incomingCh <-chan *ddp.ExtPacket)
 				// TODO: integrate this information with the routing table
 				log.Print("RTMP: Got Response or Data")
 
+			default:
+				log.Printf("RTMP: invalid DDP type %d on socket 1", pkt.Proto)
 			}
 
 		}
@@ -187,5 +190,5 @@ func (m *RTMPMachine) dataPacket(myAddr ddp.Addr) *rtmp.DataPacket {
 			},
 		},
 	}
-	// TODO: append more networks!
+	// TODO: append more networks! implement a route table!
 }