control/controlclient: add Debug field to NetworkMap

As part of disabling background STUN packets when idle, we want an
emergency override switch to turn it back on, in case it interacts
poorly in the wild. We'll send that via control, but we'll want to
plumb it down to magicsock via NetworkMap.

Updates tailscale/corp#320

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

control/controlclient/direct.go

@@ -620,6 +620,7 @@ func (c *Direct) PollNetMap(ctx context.Context, maxPolls int, cb func(*NetworkM
 			Hostinfo:     resp.Node.Hostinfo,
 			PacketFilter: c.parsePacketFilter(resp.PacketFilter),
 			DERPMap:      lastDERPMap,
+			Debug:        resp.Debug,
 		}
 		for _, profile := range resp.UserProfiles {
 			nm.UserProfiles[profile.ID] = profile

control/controlclient/netmap.go

@@ -39,6 +39,9 @@ type NetworkMap struct {
 	// between updates and should not be modified.
 	DERPMap *tailcfg.DERPMap
 
+	// Debug knobs from control server for debug or feature gating.
+	Debug *tailcfg.Debug
+
 	// ACLs
 
 	User   tailcfg.UserID
@@ -70,9 +73,17 @@ func (nm NetworkMap) String() string {
 
 func (nm *NetworkMap) Concise() string {
 	buf := new(strings.Builder)
-	fmt.Fprintf(buf, "netmap: self: %v auth=%v :%v %v\n",
-		nm.NodeKey.ShortString(), nm.MachineStatus,
-		nm.LocalPort, nm.Addresses)
+	fmt.Fprintf(buf, "netmap: self: %v auth=%v",
+		nm.NodeKey.ShortString(), nm.MachineStatus)
+	if nm.LocalPort != 0 {
+		fmt.Fprintf(buf, " port=%v", nm.LocalPort)
+	}
+	if nm.Debug != nil {
+		j, _ := json.Marshal(nm.Debug)
+		fmt.Fprintf(buf, " debug=%s", j)
+	}
+	fmt.Fprintf(buf, " %v", nm.Addresses)
+	buf.WriteByte('\n')
 	for _, p := range nm.Peers {
 		aip := make([]string, len(p.AllowedIPs))
 		for i, a := range p.AllowedIPs {

control/controlclient/netmap_test.go

@@ -11,26 +11,62 @@ import (
 )
 
 func TestNetworkMapConcise(t *testing.T) {
-	nm := &NetworkMap{
+	nodekey := func(b byte) (ret tailcfg.NodeKey) {
+		for i := range ret {
+			ret[i] = b
+		}
+		return
+	}
+	for _, tt := range []struct {
+		name string
+		nm   *NetworkMap
+		want string
+	}{
+		{
+			name: "basic",
+			nm: &NetworkMap{
+				NodeKey: nodekey(1),
 				Peers: []*tailcfg.Node{
 					{
-				Name:      "foo",
+						Key:       nodekey(2),
+						DERP:      "127.3.3.40:2",
 						Endpoints: []string{"192.168.0.100:12", "192.168.0.100:12354"},
 					},
 					{
-				Name:      "bar",
+						Key:       nodekey(3),
+						DERP:      "127.3.3.40:4",
 						Endpoints: []string{"10.2.0.100:12", "10.1.0.100:12345"},
 					},
 				},
-	}
+			},
+			want: "netmap: self: [AQEBA] auth=machine-unknown []\n [AgICA] D2                 :    192.168.0.100:12     192.168.0.100:12354\n [AwMDA] D4                 :       10.2.0.100:12        10.1.0.100:12345\n",
+		},
+		{
+			name: "debug_non_nil",
+			nm: &NetworkMap{
+				NodeKey: nodekey(1),
+				Debug:   &tailcfg.Debug{},
+			},
+			want: "netmap: self: [AQEBA] auth=machine-unknown debug={} []\n",
+		},
+		{
+			name: "debug_values",
+			nm: &NetworkMap{
+				NodeKey: nodekey(1),
+				Debug:   &tailcfg.Debug{LogHeapPprof: true},
+			},
+			want: "netmap: self: [AQEBA] auth=machine-unknown debug={\"LogHeapPprof\":true} []\n",
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
 			var got string
 			n := int(testing.AllocsPerRun(1000, func() {
-		got = nm.Concise()
+				got = tt.nm.Concise()
 			}))
 			t.Logf("Allocs = %d", n)
-	want := "netmap: self: [AAAAA] auth=machine-unknown :0 []\n" +
-		" [AAAAA]                    :    192.168.0.100:12     192.168.0.100:12354\n [AAAAA]                    :       10.2.0.100:12        10.1.0.100:12345\n"
-	if got != want {
-		t.Errorf("Wrong output\n Got: %q\nWant: %q\n## Got (unescaped):\n%s\n## Want (unescaped):\n%s\n", got, want, got, want)
+			if got != tt.want {
+				t.Errorf("Wrong output\n Got: %q\nWant: %q\n## Got (unescaped):\n%s\n## Want (unescaped):\n%s\n", got, tt.want, got, tt.want)
+			}
+		})
 	}
 }