util: add parse fallback helpers (#20022)

util/def: add def.Bool and def.Duration default parse helpers

Replace multiple instances of def.Bool and def.Duration with a new util/def
package.

Updates #20018

Co-authored-by: Bobby <boby@codelabs.co.id>
Co-authored-by: Simon Law <sfllaw@tailscale.com>
Signed-off-by: Bobby <boby@codelabs.co.id>
Signed-off-by: Simon Law <sfllaw@tailscale.com>

feature/debugportmapper/debugportmapper.go

@@ -11,7 +11,6 @@ import (
 	"net"
 	"net/http"
 	"net/netip"
-	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -20,6 +19,7 @@ import (
 	"tailscale.com/net/netmon"
 	"tailscale.com/net/portmapper"
 	"tailscale.com/types/logger"
+	"tailscale.com/util/def"
 	"tailscale.com/util/eventbus"
 )
 
@@ -66,7 +66,7 @@ func serveDebugPortmap(h *localapi.Handler, w http.ResponseWriter, r *http.Reque
 		}
 	}
 
-	if defBool(r.FormValue("log_http"), false) {
+	if def.Bool(r.FormValue("log_http"), false) {
 		debugKnobs.LogHTTP = true
 	}
 
@@ -191,14 +191,3 @@ func serveDebugPortmap(h *localapi.Handler, w http.ResponseWriter, r *http.Reque
 		}
 	}
 }
-
-func defBool(a string, def bool) bool {
-	if a == "" {
-		return def
-	}
-	v, err := strconv.ParseBool(a)
-	if err != nil {
-		return def
-	}
-	return v
-}

feature/routecheck/localapi.go

@@ -5,7 +5,6 @@ package routecheck
 
 import (
 	"net/http"
-	"strconv"
 	"time"
 
 	jsonv2 "github.com/go-json-experiment/json"
@@ -13,6 +12,7 @@ import (
 
 	"tailscale.com/ipn/localapi"
 	"tailscale.com/net/routecheck"
+	"tailscale.com/util/def"
 	"tailscale.com/util/httpm"
 )
 
@@ -39,8 +39,8 @@ func serveRouteCheck(h *localapi.Handler, w http.ResponseWriter, r *http.Request
 
 	var err error
 	var report *routecheck.Report
-	if defBool(r.FormValue("probe"), false) {
-		timeout := defDuration(r.FormValue("timeout"), routecheck.DefaultTimeout)
+	if def.Bool(r.FormValue("probe"), false) {
+		timeout := def.Duration(r.FormValue("timeout"), routecheck.DefaultTimeout)
 		timeout = min(max(0, timeout), 60*time.Second) // clamp to [0s, 60s]
 		report, err = rc.Refresh(r.Context(), timeout)
 	} else {
@@ -61,25 +61,3 @@ func serveRouteCheck(h *localapi.Handler, w http.ResponseWriter, r *http.Request
 	// with its default options, marshal with DefaultOptionsV1.
 	jsonv2.MarshalWrite(w, report, jsonv1.DefaultOptionsV1())
 }
-
-func defBool(a string, def bool) bool {
-	if a == "" {
-		return def
-	}
-	v, err := strconv.ParseBool(a)
-	if err != nil {
-		return def
-	}
-	return v
-}
-
-func defDuration(a string, def time.Duration) time.Duration {
-	if a == "" {
-		return def
-	}
-	v, err := time.ParseDuration(a)
-	if err != nil {
-		return def
-	}
-	return v
-}