health, controlclient, ipn, magicsock: tell health package state of things

Not yet checking anything. Just plumbing states into the health package.

Updates #1505

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

health/health.go

@@ -8,12 +8,28 @@ package health
 
 import (
 	"sync"
+	"time"
+
+	"tailscale.com/tailcfg"
 )
 
 var (
-	mu       sync.Mutex
+	// mu guards everything in this var block.
+	mu sync.Mutex
+
 	m        = map[string]error{}                     // error key => err (or nil for no error)
 	watchers = map[*watchHandle]func(string, error){} // opt func to run if error state changes
+
+	inMapPoll               bool
+	inMapPollSince          time.Time
+	lastMapPollEndedAt      time.Time
+	lastStreamedMapResponse time.Time
+	derpHomeRegion          int
+	derpRegionConnected     = map[int]bool{}
+	derpRegionLastFrame     = map[int]time.Time{}
+	lastMapRequestHeard     time.Time // time we got a 200 from control for a MapRequest
+	ipnState                string
+	ipnWantRunning          bool
 )
 
 type watchHandle byte
@@ -53,6 +69,7 @@ func set(key string, err error) {
 	if !ok && err == nil {
 		// Initial happy path.
 		m[key] = nil
+		selfCheckLocked()
 		return
 	}
 	if ok && (old == nil) == (err == nil) {
@@ -65,7 +82,88 @@ func set(key string, err error) {
 		return
 	}
 	m[key] = err
+	selfCheckLocked()
 	for _, cb := range watchers {
 		go cb(key, err)
 	}
 }
+
+// GotStreamedMapResponse notes that we got a tailcfg.MapResponse
+// message in streaming mode, even if it's just a keep-alive message.
+func GotStreamedMapResponse() {
+	mu.Lock()
+	defer mu.Unlock()
+	lastStreamedMapResponse = time.Now()
+	selfCheckLocked()
+}
+
+// SetInPollNetMap records that we're in
+func SetInPollNetMap(v bool) {
+	mu.Lock()
+	defer mu.Unlock()
+	if v == inMapPoll {
+		return
+	}
+	inMapPoll = v
+	if v {
+		inMapPollSince = time.Now()
+	} else {
+		lastMapPollEndedAt = time.Now()
+	}
+}
+
+// SetMagicSockDERPHome notes what magicsock's view of its home DERP is.
+func SetMagicSockDERPHome(region int) {
+	mu.Lock()
+	defer mu.Unlock()
+	derpHomeRegion = region
+	selfCheckLocked()
+}
+
+// NoteMapRequestHeard notes whenever we successfully sent a map request
+// to control for which we received a 200 response.
+func NoteMapRequestHeard(mr *tailcfg.MapRequest) {
+	mu.Lock()
+	defer mu.Unlock()
+	// TODO: extract mr.HostInfo.NetInfo.PreferredDERP, compare
+	// against SetMagicSockDERPHome and
+	// SetDERPRegionConnectedState
+
+	lastMapRequestHeard = time.Now()
+	selfCheckLocked()
+}
+
+func SetDERPRegionConnectedState(region int, connected bool) {
+	mu.Lock()
+	defer mu.Unlock()
+	derpRegionConnected[region] = connected
+	selfCheckLocked()
+}
+
+func NoteDERPRegionReceivedFrame(region int) {
+	mu.Lock()
+	defer mu.Unlock()
+	derpRegionLastFrame[region] = time.Now()
+	selfCheckLocked()
+}
+
+// state is an ipn.State.String() value: "Running", "Stopped", "NeedsLogin", etc.
+func SetIPNState(state string, wantRunning bool) {
+	mu.Lock()
+	defer mu.Unlock()
+	ipnState = state
+	ipnWantRunning = wantRunning
+	selfCheckLocked()
+}
+
+func selfCheckLocked() {
+	// TODO: check states against each other.
+	// For staticcheck for now:
+	_ = inMapPollSince
+	_ = lastMapPollEndedAt
+	_ = lastStreamedMapResponse
+	_ = derpHomeRegion
+	_ = lastMapRequestHeard
+	_ = ipnState
+	_ = ipnWantRunning
+}