Routing table simplifications

main.go

@@ -131,10 +131,7 @@ func main() {
 	}
 
 	// ----------------------------- Routing table ----------------------------
-	routing := &routingTable{
-		table:     make(map[ddp.Network][]*route),
-		allRoutes: make(map[*route]struct{}),
-	}
+	routing := NewRoutingTable()
 
 	// ------------------------- Configured peer setup ------------------------
 	for _, peerStr := range cfg.Peers {
@@ -250,15 +247,15 @@ func main() {
 				// addressed to a node on the local network."
 				if ddpkt.DstNet != 0 && (ddpkt.DstNet < cfg.EtherTalk.NetStart || ddpkt.DstNet > cfg.EtherTalk.NetEnd) {
 					// Is it for a network in the routing table?
-					rt := routing.lookupRoute(ddpkt.DstNet)
+					rt := routing.LookupRoute(ddpkt.DstNet)
 					if rt == nil {
 						log.Printf("DDP: no route for network %d", ddpkt.DstNet)
 						continue
 					}
 
 					// Encap ethPacket.Payload into an AURP packet
-					log.Printf("DDP: forwarding to AURP peer %v", rt.peer.tr.RemoteDI)
-					if _, err := rt.peer.send(rt.peer.tr.NewAppleTalkPacket(ethFrame.Payload)); err != nil {
+					log.Printf("DDP: forwarding to AURP peer %v", rt.Peer.tr.RemoteDI)
+					if _, err := rt.Peer.send(rt.Peer.tr.NewAppleTalkPacket(ethFrame.Payload)); err != nil {
 						log.Printf("DDP: Couldn't forward packet to AURP peer: %v", err)
 					}
 

peer.go

@@ -82,7 +82,7 @@ type peer struct {
 	raddr *net.UDPAddr
 	recv  chan aurp.Packet
 
-	routingTable *routingTable
+	routingTable *RoutingTable
 }
 
 // send encodes and sends pkt to the remote host.
@@ -279,7 +279,7 @@ func (p *peer) handle(ctx context.Context) error {
 				log.Printf("Learned about these networks: %v", pkt.Networks)
 
 				for _, nt := range pkt.Networks {
-					p.routingTable.upsertRoutes(
+					p.routingTable.UpsertRoute(
 						nt.Extended,
 						ddp.Network(nt.RangeStart),
 						ddp.Network(nt.RangeEnd),

route.go

@@ -1,9 +1,7 @@
 package main
 
 import (
-	"cmp"
 	"fmt"
-	"slices"
 	"sync"
 	"time"
 
@@ -12,74 +10,83 @@ import (
 
 const maxRouteAge = 10 * time.Minute // TODO: confirm
 
-type route struct {
-	extended bool
-	netStart ddp.Network
-	netEnd   ddp.Network
-	peer     *peer
-	metric   uint8
-	last     time.Time
+type Route struct {
+	Extended bool
+	NetStart ddp.Network
+	NetEnd   ddp.Network
+	Peer     *peer
+	Distance uint8
+	LastSeen time.Time
 }
 
-type routingTable struct {
-	tableMu sync.Mutex
-	table   map[ddp.Network][]*route
-
-	allRoutesMu sync.Mutex
-	allRoutes   map[*route]struct{}
+type RoutingTable struct {
+	mu     sync.Mutex
+	routes map[*Route]struct{}
 }
 
-func (rt *routingTable) lookupRoute(network ddp.Network) *route {
-	rt.tableMu.Lock()
-	defer rt.tableMu.Unlock()
+func NewRoutingTable() *RoutingTable {
+	return &RoutingTable{
+		routes: make(map[*Route]struct{}),
+	}
+}
 
-	for _, rs := range rt.table[network] {
-		if time.Since(rs.last) > maxRouteAge {
+func (rt *RoutingTable) LookupRoute(network ddp.Network) *Route {
+	rt.mu.Lock()
+	defer rt.mu.Unlock()
+
+	var bestRoute *Route
+	for r := range rt.routes {
+		if r.Peer == nil {
 			continue
 		}
-		return rs
+		if network < r.NetStart || network > r.NetEnd {
+			continue
 		}
-	return nil
+		if time.Since(r.LastSeen) > maxRouteAge {
+			continue
+		}
+		if bestRoute == nil {
+			bestRoute = r
+			continue
+		}
+		if r.Distance < bestRoute.Distance {
+			bestRoute = r
+		}
+	}
+	return bestRoute
 }
 
-func (rt *routingTable) upsertRoutes(extended bool, netStart, netEnd ddp.Network, peer *peer, metric uint8) error {
+func (rt *RoutingTable) UpsertRoute(extended bool, netStart, netEnd ddp.Network, peer *peer, metric uint8) error {
 	if netStart > netEnd {
 		return fmt.Errorf("invalid network range [%d, %d]", netStart, netEnd)
 	}
 
-	r := &route{
-		extended: extended,
-		netStart: netStart,
-		netEnd:   netEnd,
-		peer:     peer,
-		metric:   metric,
-		last:     time.Now(),
+	// TODO: handle the Update part of "Upsert"
+
+	r := &Route{
+		Extended: extended,
+		NetStart: netStart,
+		NetEnd:   netEnd,
+		Peer:     peer,
+		Distance: metric,
+		LastSeen: time.Now(),
 	}
 
-	rt.allRoutesMu.Lock()
-	rt.allRoutes[r] = struct{}{}
-	rt.allRoutesMu.Unlock()
-
-	rt.tableMu.Lock()
-	defer rt.tableMu.Unlock()
-	for n := netStart; n <= netEnd; n++ {
-		rt.table[n] = append(rt.table[n], r)
-		slices.SortFunc(rt.table[n], func(r, s *route) int {
-			return cmp.Compare(r.metric, s.metric)
-		})
-	}
+	rt.mu.Lock()
+	defer rt.mu.Unlock()
+	rt.routes[r] = struct{}{}
 	return nil
 }
 
-func (rt *routingTable) validRoutes() []*route {
-	rt.allRoutesMu.Lock()
-	defer rt.allRoutesMu.Unlock()
-	valid := make([]*route, 0, len(rt.allRoutes))
-	for r := range rt.allRoutes {
-		if r.peer == nil {
+func (rt *RoutingTable) ValidRoutes() []*Route {
+	rt.mu.Lock()
+	defer rt.mu.Unlock()
+	valid := make([]*Route, 0, len(rt.routes))
+	for r := range rt.routes {
+		if r.Peer == nil {
 			continue
 		}
-		if time.Since(r.last) > maxRouteAge {
+		if time.Since(r.LastSeen) > maxRouteAge {
 			continue
 		}
 		valid = append(valid, r)

rtmp.go

@@ -35,7 +35,7 @@ type RTMPMachine struct {
 	aarp         *AARPMachine
 	cfg          *config
 	pcapHandle   *pcap.Handle
-	routingTable *routingTable
+	routingTable *RoutingTable
 }
 
 // Run executes the machine.
@@ -214,12 +214,12 @@ func (m *RTMPMachine) dataPacket(myAddr ddp.Addr) *rtmp.DataPacket {
 			},
 		},
 	}
-	for _, rt := range m.routingTable.validRoutes() {
+	for _, rt := range m.routingTable.ValidRoutes() {
 		p.NetworkTuples = append(p.NetworkTuples, rtmp.NetworkTuple{
-			Extended:   rt.extended,
-			RangeStart: rt.netStart,
-			RangeEnd:   rt.netEnd,
-			Distance:   rt.metric + 1,
+			Extended:   rt.Extended,
+			RangeStart: rt.NetStart,
+			RangeEnd:   rt.NetEnd,
+			Distance:   rt.Distance + 1,
 		})
 	}
 	return p