wip

client/tailscale/localclient.go

@@ -1417,12 +1417,16 @@ func (lc *LocalClient) CheckUpdate(ctx context.Context) (*tailcfg.ClientVersion,
 	return &cv, nil
 }
 
-func (lc *LocalClient) SuggestExitNode(ctx context.Context) error {
+func (lc *LocalClient) SuggestExitNode(ctx context.Context) (*tailcfg.StableNodeID, error) {
 	body, err := lc.send(ctx, "POST", "/localapi/v0/suggest-exit-node", 200, nil)
 	if err != nil {
-		return fmt.Errorf("error %w: %s", err, body)
+		return nil, fmt.Errorf("error %w: %s", err, body)
 	}
-	return nil
+	nodeID, err := decodeJSON[tailcfg.StableNodeID](body)
+	if err != nil {
+		return nil, err
+	}
+	return &nodeID, nil
 }
 
 // IPNBusWatcher is an active subscription (watch) of the local tailscaled IPN bus.

cmd/tailscale/cli/exitnode.go

@@ -16,6 +16,7 @@
 
 	"github.com/peterbourgon/ff/v3/ffcli"
 	xmaps "golang.org/x/exp/maps"
+	"tailscale.com/ipn"
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/tailcfg"
 )
@@ -107,16 +108,32 @@ func runExitNodeList(ctx context.Context, args []string) error {
 	}
 	fmt.Fprintln(w)
 	fmt.Fprintln(w)
-	fmt.Fprintln(w, "# To use an exit node, use `tailscale set --exit-node=` followed by the hostname or IP")
+	fmt.Fprintln(w, "# To use an exit node, use `tailscale set --exit-node=` followed by the hostname or IP. Or `tailscale exit-node suggest` to have Tailscale pick an exit node for you.")
 
 	return nil
 }
 
 func runExitNodeSuggest(ctx context.Context, args []string) error {
-	err := localClient.SuggestExitNode(ctx)
+	var suggestedNodeID *tailcfg.StableNodeID
+	suggestedNodeID, err := localClient.SuggestExitNode(ctx)
+	if suggestedNodeID == nil {
+		fmt.Println("Unable to suggest exit node")
+	} else {
+		fmt.Printf("Chosen exit node id: %v", *suggestedNodeID)
+	}
 	if err != nil {
 		return fmt.Errorf("Failed to suggest exit node. Error: %v", err)
 	}
+	_, err = localClient.EditPrefs(ctx, &ipn.MaskedPrefs{
+		Prefs: ipn.Prefs{
+			ExitNodeID: *suggestedNodeID,
+		},
+		ExitNodeIDSet: true,
+	})
+
+	if err != nil {
+		return fmt.Errorf("Failed to set suggested exit node. Error: %v", err)
+	}
 	return nil
 }
 

ipn/ipnlocal/local.go

@@ -309,8 +309,7 @@ type LocalBackend struct {
 	clock       tstime.Clock
 
 	// Last ClientVersion received in MapResponse, guarded by mu.
-	lastClientVersion    *tailcfg.ClientVersion
-	suggestedExitNodeMap map[tailcfg.NodeID]tailcfg.DERPRegion
+	lastClientVersion *tailcfg.ClientVersion
 }
 
 type updateStatus struct {
@@ -5913,35 +5912,64 @@ func mayDeref[T any](p *T) (v T) {
 	return *p
 }
 
-func (b *LocalBackend) SuggestExitNode() error {
-	//b.mu.Lock()
+func (b *LocalBackend) SuggestExitNode() (*tailcfg.StableNodeID, error) {
+	b.mu.Lock()
 	netMap := b.netMap
+	if netMap == nil {
+		b.mu.Unlock()
+		return nil, errors.New("no netmap")
+	}
 	peers := netMap.Peers
 	lastReport := b.MagicConn().GetLastNetcheckReport()
 	var fastestRegionLatency = time.Duration(math.MaxInt64)
 	var preferredExitNodeID tailcfg.StableNodeID
+	peerRegionMap := make(map[int][]tailcfg.NodeView)
 	for _, peer := range peers {
-		if tsaddr.ContainsExitRoutes(peer.AllowedIPs()) && strings.HasPrefix(peer.DERP(), derpPrefix) {
+		if online := peer.Online(); online != nil && !*online {
+			continue
+		}
+		if tsaddr.ContainsExitRoutes(peer.AllowedIPs()) /*&& strings.HasPrefix(peer.DERP(), derpPrefix)*/ {
 			ipp, _ := netip.ParseAddrPort(peer.DERP())
 			regionID := int(ipp.Port())
-			if lastReport.RegionLatency[regionID] < fastestRegionLatency {
+			regionLatency, ok := lastReport.RegionLatency[regionID]
+			peerRegionMap[regionID] = append(peerRegionMap[regionID], peer)
+			b.logf("region %d latency %v(%v) node id %v", regionID, regionLatency, ok, peer.Name())
+			if ok && regionLatency < fastestRegionLatency {
 				fastestRegionLatency = lastReport.RegionLatency[regionID]
 				preferredExitNodeID = peer.StableID()
 				b.logf("fastest region latency %v preferred exit node id %v", lastReport.RegionLatency[regionID], peer.StableID())
 			}
 		}
 	}
-	//	b.mu.Unlock()
-	prefs := b.Prefs().AsStruct()
-	prefs.ExitNodeID = preferredExitNodeID
-	_, err := b.EditPrefs(&ipn.MaskedPrefs{
-		Prefs: ipn.Prefs{
-			ExitNodeID: preferredExitNodeID,
-		},
-		ExitNodeIDSet: true,
-	})
-	if err != nil {
-		return fmt.Errorf("Failed to suggest exit node %v, err %v", preferredExitNodeID, err)
+	b.logf("self derp %v", b.netMap.SelfNode.DERP())
+	ipp, _ := netip.ParseAddrPort(netMap.SelfNode.DERP())
+	selfDerpRegionID := int(ipp.Port())
+	b.logf("self derp region id %v", selfDerpRegionID)
+	sameRegionNodes, ok := peerRegionMap[selfDerpRegionID]
+	b.mu.Unlock()
+	if ok {
+		preferredExitNodeID = balancedPick(netMap.SelfNode, sameRegionNodes).StableID()
 	}
-	return nil
+	//b.logf("peer region map %v", peerRegionMap)
+	b.logf("chosen exit node id %v", preferredExitNodeID)
+	if preferredExitNodeID.IsZero() {
+		return &preferredExitNodeID, fmt.Errorf("Unable to choose exit node")
+	}
+	return &preferredExitNodeID, nil
 }
+
+func balancedPick(selfNode tailcfg.NodeView, candidates []tailcfg.NodeView) tailcfg.NodeView {
+	if len(candidates) == 1 {
+		return candidates[0]
+	} else {
+		sort.Slice(candidates, func(i, j int) bool { return candidates[i].ID() < candidates[j].ID() })
+
+		mappedID := selfNode.ID() % 512
+		chosen := candidates[int(math.Floor(float64(mappedID)/512*float64(len(candidates))))]
+		return chosen
+	}
+}
+
+/*func measureLatency(ctx context.Context, derpRegion *DERPRegion, p *ping.Pinger) (time.Duration, error) {
+	node := derpRegion.Nodes[0]
+} */

ipn/localapi/localapi.go

@@ -2515,9 +2515,10 @@ func (h *Handler) serveSuggestExitNode(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "want POST", http.StatusBadRequest)
 		return
 	}
-	err := h.b.SuggestExitNode()
+	suggestedExitNodeID, err := h.b.SuggestExitNode()
 	if err != nil {
 		writeErrorJSON(w, err)
 		return
 	}
+	json.NewEncoder(w).Encode(suggestedExitNodeID)
 }

wgengine/magicsock/magicsock.go

@@ -3010,5 +3010,6 @@ func getPeerMTUsProbedMetric(mtu tstun.WireMTU) *clientmetric.Metric {
 }
 
 func (c *Conn) GetLastNetcheckReport() *netcheck.Report {
-	return c.lastNetCheckReport.Load()
+	report, _ := c.updateNetInfo(c.connCtx)
+	return report
 }