net/packet, wgengine/{filter,tstun}: add TSMP ping

Fixes #1467

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

ipn/backend.go

@@ -165,5 +165,5 @@ type Backend interface {
 	// Ping attempts to start connecting to the given IP and sends a Notify
 	// with its PingResult. If the host is down, there might never
 	// be a PingResult sent. The cmd/tailscale CLI client adds a timeout.
-	Ping(ip string)
+	Ping(ip string, useTSMP bool)
 }

ipn/fake_test.go

@@ -91,6 +91,6 @@ func (b *FakeBackend) FakeExpireAfter(x time.Duration) {
 	b.notify(Notify{NetMap: &netmap.NetworkMap{}})
 }
 
-func (b *FakeBackend) Ping(ip string) {
+func (b *FakeBackend) Ping(ip string, useTSMP bool) {
 	b.notify(Notify{PingResult: &ipnstate.PingResult{}})
 }

ipn/ipnlocal/local.go

@@ -1173,13 +1173,13 @@ func (b *LocalBackend) FakeExpireAfter(x time.Duration) {
 	b.send(ipn.Notify{NetMap: b.netMap})
 }
 
-func (b *LocalBackend) Ping(ipStr string) {
+func (b *LocalBackend) Ping(ipStr string, useTSMP bool) {
 	ip, err := netaddr.ParseIP(ipStr)
 	if err != nil {
 		b.logf("ignoring Ping request to invalid IP %q", ipStr)
 		return
 	}
-	b.e.Ping(ip, func(pr *ipnstate.PingResult) {
+	b.e.Ping(ip, useTSMP, func(pr *ipnstate.PingResult) {
 		b.send(ipn.Notify{PingResult: pr})
 	})
 }

ipn/ipnstate/ipnstate.go

@@ -407,10 +407,18 @@ type PingResult struct {
 	Err            string
 	LatencySeconds float64
 
-	Endpoint string // ip:port if direct UDP was used
+	// Endpoint is the ip:port if direct UDP was used.
+	// It is not currently set for TSMP pings.
+	Endpoint string
 
-	DERPRegionID   int    // non-zero if DERP was used
-	DERPRegionCode string // three-letter airport/region code if DERP was used
+	// DERPRegionID is non-zero DERP region ID if DERP was used.
+	// It is not currently set for TSMP pings.
+	DERPRegionID int
+
+	// DERPRegionCode is the three-letter region code
+	// corresponding to DERPRegionID.
+	// It is not currently set for TSMP pings.
+	DERPRegionCode string
 
 	// TODO(bradfitz): details like whether port mapping was used on either side? (Once supported)
 }

ipn/message.go

@@ -56,7 +56,8 @@ type FakeExpireAfterArgs struct {
 }
 
 type PingArgs struct {
-	IP string
+	IP      string
+	UseTSMP bool
 }
 
 // Command is a command message that is JSON encoded and sent by a
@@ -174,7 +175,7 @@ func (bs *BackendServer) GotCommand(ctx context.Context, cmd *Command) error {
 		bs.b.RequestEngineStatus()
 		return nil
 	} else if c := cmd.Ping; c != nil {
-		bs.b.Ping(c.IP)
+		bs.b.Ping(c.IP, c.UseTSMP)
 		return nil
 	}
 
@@ -320,8 +321,11 @@ func (bc *BackendClient) FakeExpireAfter(x time.Duration) {
 	bc.send(Command{FakeExpireAfter: &FakeExpireAfterArgs{Duration: x}})
 }
 
-func (bc *BackendClient) Ping(ip string) {
-	bc.send(Command{Ping: &PingArgs{IP: ip}})
+func (bc *BackendClient) Ping(ip string, useTSMP bool) {
+	bc.send(Command{Ping: &PingArgs{
+		IP:      ip,
+		UseTSMP: useTSMP,
+	}})
 }
 
 func (bc *BackendClient) SetWantRunning(v bool) {