Harden resolver and expand traffic runtime controls

selective-vpn-api/app/routes_handlers.go

@@ -9,6 +9,7 @@ import (
 	"os"
 	"strings"
 	"syscall"
+	"time"
 )
 
 // ---------------------------------------------------------------------
@@ -263,6 +264,10 @@ func handleRoutesCacheRestore(w http.ResponseWriter, r *http.Request) {
 // RU: `routesClear` - содержит основную логику для routes clear.
 // ---------------------------------------------------------------------
 func routesClear() cmdResult {
+	return withRoutesOpLock("routes clear", routesClearUnlocked)
+}
+
+func routesClearUnlocked() cmdResult {
 	cacheMeta, cacheErr := saveRoutesClearCache()
 
 	stdout, stderr, _, err := runCommand("ip", "rule", "show")
@@ -273,6 +278,11 @@ func routesClear() cmdResult {
 	_, _, _, _ = runCommand("ip", "route", "flush", "table", routesTableName())
 	_, _, _, _ = runCommand("nft", "flush", "set", "inet", "agvpn", "agvpn4")
 	_, _, _, _ = runCommand("nft", "flush", "set", "inet", "agvpn", "agvpn_dyn4")
+	iface := strings.TrimSpace(cacheMeta.Iface)
+	if iface == "" {
+		iface, _ = resolveTrafficIface(loadTrafficModeState().PreferredIface)
+	}
+	_ = writeStatusSnapshot(0, iface)
 
 	res := cmdResult{
 		OK:       true,
@@ -297,6 +307,50 @@ func routesClear() cmdResult {
 	return res
 }
 
+func withRoutesOpLock(opName string, fn func() cmdResult) cmdResult {
+	lock, err := os.OpenFile(lockFile, os.O_CREATE|os.O_RDWR, 0o644)
+	if err != nil {
+		return cmdResult{
+			OK:      false,
+			Message: fmt.Sprintf("%s lock open error: %v", opName, err),
+		}
+	}
+	defer lock.Close()
+
+	if err := syscall.Flock(int(lock.Fd()), syscall.LOCK_EX|syscall.LOCK_NB); err != nil {
+		return cmdResult{
+			OK:      false,
+			Message: fmt.Sprintf("%s skipped: routes operation already running", opName),
+		}
+	}
+	defer syscall.Flock(int(lock.Fd()), syscall.LOCK_UN)
+
+	return fn()
+}
+
+func writeStatusSnapshot(ipCount int, iface string) error {
+	if ipCount < 0 {
+		ipCount = 0
+	}
+	iface = strings.TrimSpace(iface)
+	if iface == "" {
+		iface = "-"
+	}
+	st := Status{
+		Timestamp:   time.Now().UTC().Format(time.RFC3339),
+		IPCount:     ipCount,
+		DomainCount: countDomainsFromMap(lastIPsMapPath),
+		Iface:       iface,
+		Table:       routesTableName(),
+		Mark:        MARK,
+	}
+	data, err := json.MarshalIndent(st, "", "  ")
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(statusFilePath, data, 0o644)
+}
+
 // ---------------------------------------------------------------------
 // policy route
 // ---------------------------------------------------------------------