From 1bd203c5555046b7ee4fbfe2f822eb3d03571ad7 Mon Sep 17 00:00:00 2001
From: SergeiEU <39683682+SergeiEU@users.noreply.github.com>
Date: Wed, 1 Apr 2026 10:17:15 +0400
Subject: Initial import

---
 internal/engine/watchdog.go | 142 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 142 insertions(+)
 create mode 100644 internal/engine/watchdog.go

(limited to 'internal/engine/watchdog.go')

diff --git a/internal/engine/watchdog.go b/internal/engine/watchdog.go
new file mode 100644
index 0000000..899f81f
--- /dev/null
+++ b/internal/engine/watchdog.go
@@ -0,0 +1,142 @@
+package engine
+
+import (
+	"context"
+	"io"
+	"log"
+	"net/http"
+	"strings"
+	"time"
+
+	"vpnem/internal/config"
+	"vpnem/internal/models"
+)
+
+// WatchdogConfig holds watchdog parameters.
+type WatchdogConfig struct {
+	CheckInterval    time.Duration // how often to check sing-box is alive (default 2s)
+	DeepCheckInterval time.Duration // how often to verify exit IP (default 30s)
+	ReconnectCooldown time.Duration // min time between reconnect attempts (default 5s)
+}
+
+// DefaultWatchdogConfig returns the default watchdog settings (from vpn.py).
+func DefaultWatchdogConfig() WatchdogConfig {
+	return WatchdogConfig{
+		CheckInterval:     2 * time.Second,
+		DeepCheckInterval: 30 * time.Second,
+		ReconnectCooldown: 5 * time.Second,
+	}
+}
+
+// Watchdog monitors sing-box and auto-reconnects on failure.
+type Watchdog struct {
+	engine    *Engine
+	cfg       WatchdogConfig
+	cancel    context.CancelFunc
+	running   bool
+
+	// Reconnect parameters (set via StartWatching)
+	server    models.Server
+	mode      config.Mode
+	ruleSets  []models.RuleSet
+	serverIPs []string
+}
+
+// NewWatchdog creates a new watchdog for the given engine.
+func NewWatchdog(engine *Engine, cfg WatchdogConfig) *Watchdog {
+	return &Watchdog{
+		engine: engine,
+		cfg:    cfg,
+	}
+}
+
+// StartWatching begins monitoring. It stores the connection params for reconnection.
+func (w *Watchdog) StartWatching(server models.Server, mode config.Mode, ruleSets []models.RuleSet, serverIPs []string) {
+	w.StopWatching()
+
+	w.server = server
+	w.mode = mode
+	w.ruleSets = ruleSets
+	w.serverIPs = serverIPs
+
+	ctx, cancel := context.WithCancel(context.Background())
+	w.cancel = cancel
+	w.running = true
+
+	go w.loop(ctx)
+}
+
+// StopWatching stops the watchdog.
+func (w *Watchdog) StopWatching() {
+	if w.cancel != nil {
+		w.cancel()
+	}
+	w.running = false
+}
+
+// IsWatching returns whether the watchdog is active.
+func (w *Watchdog) IsWatching() bool {
+	return w.running
+}
+
+func (w *Watchdog) loop(ctx context.Context) {
+	ticker := time.NewTicker(w.cfg.CheckInterval)
+	defer ticker.Stop()
+
+	deepTicker := time.NewTicker(w.cfg.DeepCheckInterval)
+	defer deepTicker.Stop()
+
+	lastReconnect := time.Time{}
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+
+		case <-ticker.C:
+			if !w.engine.IsRunning() {
+				if time.Since(lastReconnect) < w.cfg.ReconnectCooldown {
+					continue
+				}
+				log.Println("watchdog: sing-box not running, reconnecting...")
+				if err := w.engine.Start(w.server, w.mode, w.ruleSets, w.serverIPs); err != nil {
+					log.Printf("watchdog: reconnect failed: %v", err)
+				} else {
+					log.Println("watchdog: reconnected successfully")
+				}
+				lastReconnect = time.Now()
+			}
+
+		case <-deepTicker.C:
+			if !w.engine.IsRunning() {
+				continue
+			}
+			ip := checkExitIP()
+			if ip == "" {
+				log.Println("watchdog: deep check failed (no exit IP), restarting...")
+				if time.Since(lastReconnect) < w.cfg.ReconnectCooldown {
+					continue
+				}
+				if err := w.engine.Restart(w.server, w.mode, w.ruleSets, w.serverIPs); err != nil {
+					log.Printf("watchdog: restart failed: %v", err)
+				}
+				lastReconnect = time.Now()
+			}
+		}
+	}
+}
+
+func checkExitIP() string {
+	client := &http.Client{Timeout: 5 * time.Second}
+	resp, err := client.Get("http://ifconfig.me/ip")
+	if err != nil {
+		return ""
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(io.LimitReader(resp.Body, 64))
+	if err != nil {
+		return ""
+	}
+	return strings.TrimSpace(string(body))
+}
-- 
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