tailcfg: add Hostinfo.Package

Updates tailscale/corp#440

(cherry picked from commit 73552eb32e)

tailcfg/tailcfg.go

@@ -406,6 +406,7 @@ type Hostinfo struct {
 	BackendLogID  string             `json:",omitempty"` // logtail ID of backend instance
 	OS            string             // operating system the client runs on (a version.OS value)
 	OSVersion     string             `json:",omitempty"` // operating system version, with optional distro prefix ("Debian 10.4", "Windows 10 Pro 10.0.19041")
+	Package       string             `json:",omitempty"` // Tailscale package to disambiguate ("choco", "appstore", etc; "" for unknown)
 	DeviceModel   string             `json:",omitempty"` // mobile phone model ("Pixel 3a", "iPhone 11 Pro")
 	Hostname      string             // name of the host the client runs on
 	ShieldsUp     bool               `json:",omitempty"` // indicates whether the host is blocking incoming connections

tailcfg/tailcfg_clone.go

@@ -107,6 +107,7 @@ var _HostinfoNeedsRegeneration = Hostinfo(struct {
 	BackendLogID  string
 	OS            string
 	OSVersion     string
+	Package       string
 	DeviceModel   string
 	Hostname      string
 	ShieldsUp     bool

tailcfg/tailcfg_test.go

@@ -25,7 +25,7 @@ func fieldsOf(t reflect.Type) (fields []string) {
 func TestHostinfoEqual(t *testing.T) {
 	hiHandles := []string{
 		"IPNVersion", "FrontendLogID", "BackendLogID",
-		"OS", "OSVersion", "DeviceModel", "Hostname",
+		"OS", "OSVersion", "Package", "DeviceModel", "Hostname",
 		"ShieldsUp", "ShareeNode",
 		"GoArch",
 		"RoutableIPs", "RequestTags",