tailcfg: add location field to hostinfo

This change adds Location field to HostInfo.
Location contains the option for a Country, CountryCode, City, CityCode
and a Priority. Neither of these fields are populated by default.

The Priority field is used to determine the priority an exit
node should be given for use, if the field is set. The higher the value
set, the higher priority the node should be given for use.

Updates tailscale/corp#12146

Signed-off-by: Charlotte Brandhorst-Satzkorn <charlotte@tailscale.com>

tailcfg/tailcfg_view.go

@@ -20,7 +20,7 @@ import (
 	"tailscale.com/types/views"
 )
 
-//go:generate go run tailscale.com/cmd/cloner  -clonefunc=true -type=User,Node,Hostinfo,NetInfo,Login,DNSConfig,RegisterResponse,DERPRegion,DERPMap,DERPNode,SSHRule,SSHAction,SSHPrincipal,ControlDialPlan
+//go:generate go run tailscale.com/cmd/cloner  -clonefunc=true -type=User,Node,Hostinfo,NetInfo,Login,DNSConfig,RegisterResponse,DERPRegion,DERPMap,DERPNode,SSHRule,SSHAction,SSHPrincipal,ControlDialPlan,Location
 
 // View returns a readonly view of User.
 func (p *User) View() UserView {
@@ -303,7 +303,15 @@ func (v HostinfoView) SSH_HostKeys() views.Slice[string] { return views.SliceOf(
 func (v HostinfoView) Cloud() string                     { return v.ж.Cloud }
 func (v HostinfoView) Userspace() opt.Bool               { return v.ж.Userspace }
 func (v HostinfoView) UserspaceRouter() opt.Bool         { return v.ж.UserspaceRouter }
-func (v HostinfoView) Equal(v2 HostinfoView) bool        { return v.ж.Equal(v2.ж) }
+func (v HostinfoView) Location() *Location {
+	if v.ж.Location == nil {
+		return nil
+	}
+	x := *v.ж.Location
+	return &x
+}
+
+func (v HostinfoView) Equal(v2 HostinfoView) bool { return v.ж.Equal(v2.ж) }
 
 // A compilation failure here means this code must be regenerated, with the command at the top of this file.
 var _HostinfoViewNeedsRegeneration = Hostinfo(struct {
@@ -340,6 +348,7 @@ var _HostinfoViewNeedsRegeneration = Hostinfo(struct {
 	Cloud           string
 	Userspace       opt.Bool
 	UserspaceRouter opt.Bool
+	Location        *Location
 }{})
 
 // View returns a readonly view of NetInfo.
@@ -1077,3 +1086,63 @@ func (v ControlDialPlanView) Candidates() views.Slice[ControlIPCandidate] {
 var _ControlDialPlanViewNeedsRegeneration = ControlDialPlan(struct {
 	Candidates []ControlIPCandidate
 }{})
+
+// View returns a readonly view of Location.
+func (p *Location) View() LocationView {
+	return LocationView{ж: p}
+}
+
+// LocationView provides a read-only view over Location.
+//
+// Its methods should only be called if `Valid()` returns true.
+type LocationView struct {
+	// ж is the underlying mutable value, named with a hard-to-type
+	// character that looks pointy like a pointer.
+	// It is named distinctively to make you think of how dangerous it is to escape
+	// to callers. You must not let callers be able to mutate it.
+	ж *Location
+}
+
+// Valid reports whether underlying value is non-nil.
+func (v LocationView) Valid() bool { return v.ж != nil }
+
+// AsStruct returns a clone of the underlying value which aliases no memory with
+// the original.
+func (v LocationView) AsStruct() *Location {
+	if v.ж == nil {
+		return nil
+	}
+	return v.ж.Clone()
+}
+
+func (v LocationView) MarshalJSON() ([]byte, error) { return json.Marshal(v.ж) }
+
+func (v *LocationView) UnmarshalJSON(b []byte) error {
+	if v.ж != nil {
+		return errors.New("already initialized")
+	}
+	if len(b) == 0 {
+		return nil
+	}
+	var x Location
+	if err := json.Unmarshal(b, &x); err != nil {
+		return err
+	}
+	v.ж = &x
+	return nil
+}
+
+func (v LocationView) Country() string     { return v.ж.Country }
+func (v LocationView) CountryCode() string { return v.ж.CountryCode }
+func (v LocationView) City() string        { return v.ж.City }
+func (v LocationView) CityCode() string    { return v.ж.CityCode }
+func (v LocationView) Priority() int       { return v.ж.Priority }
+
+// A compilation failure here means this code must be regenerated, with the command at the top of this file.
+var _LocationViewNeedsRegeneration = Location(struct {
+	Country     string
+	CountryCode string
+	City        string
+	CityCode    string
+	Priority    int
+}{})