feat(watchdog): add watchdog service with TCP client implementation

- Implement TCP client for watchdog service communication
- Add watchdog configuration in config.json
- Update main.go to initialize and connect to watchdog
- Add watchdog related functions (connect, command handling)
- Update README.md with new watchdog feature
- Improve route setup logging in router.go

watchdog/tcpClient.go

@@ -0,0 +1,164 @@
+package watchdog
+
+import (
+	"bufio"
+	"fmt"
+	"net"
+	"super-frpc/postLog"
+	"sync"
+	"time"
+)
+
+var (
+	tcpConn      net.Conn
+	tcpConnMutex sync.Mutex
+	isConnected  bool
+	recvChan     chan string
+	stopRecvChan chan struct{}
+)
+
+func notifyMessage(message string) {
+	postLog.Info(fmt.Sprintf("%s", message))
+}
+
+func Init() error {
+	tcpConnMutex.Lock()
+	defer tcpConnMutex.Unlock()
+
+	if tcpConn != nil {
+		return fmt.Errorf("TCP client already initialized")
+	}
+
+	recvChan = make(chan string, 100)
+	stopRecvChan = make(chan struct{})
+	isConnected = false
+
+	return nil
+}
+
+func tcpConnect(ipaddr string, port int) error {
+	tcpConnMutex.Lock()
+	defer tcpConnMutex.Unlock()
+
+	if tcpConn != nil {
+		return fmt.Errorf("already connected")
+	}
+
+	address := fmt.Sprintf("%s:%d", ipaddr, port)
+	conn, err := net.DialTimeout("tcp", address, 3*time.Second)
+	if err != nil {
+		return fmt.Errorf("failed to connect to %s: %v", address, err)
+	}
+
+	tcpConn = conn
+	isConnected = true
+
+	go recvMsg()
+
+	return nil
+}
+
+func sendMsg(message string, target int) (string, error) {
+	tcpConnMutex.Lock()
+
+	if tcpConn == nil {
+		tcpConnMutex.Unlock()
+		return "", fmt.Errorf("not connected")
+	}
+
+	_, err := tcpConn.Write([]byte(message + "\n"))
+	if err != nil {
+		tcpConnMutex.Unlock()
+		return "", fmt.Errorf("failed to send message: %v", err)
+	}
+
+	tcpConnMutex.Unlock()
+
+	select {
+	case response := <-recvChan:
+		return response, nil
+	case <-time.After(time.Duration(target) * time.Second):
+		return "", fmt.Errorf("timeout waiting for response")
+	}
+}
+
+func recvMsg() {
+	reader := bufio.NewReader(tcpConn)
+	for {
+		select {
+		case <-stopRecvChan:
+			return
+		default:
+			tcpConn.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
+			line, err := reader.ReadString('\n')
+			if err != nil {
+				if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
+					continue
+				}
+				tcpConnMutex.Lock()
+				if tcpConn != nil {
+					tcpConn.Close()
+					tcpConn = nil
+					isConnected = false
+				}
+				tcpConnMutex.Unlock()
+				return
+			}
+
+			line = line[:len(line)-1]
+			if len(line) > 0 {
+				select {
+				case recvChan <- line:
+				default:
+					select {
+					case <-recvChan:
+						recvChan <- line
+					default:
+					}
+				}
+
+				if len(line) > 0 && line != "success" && !isResponseMessage(line) {
+					notifyMessage(line)
+				}
+			}
+		}
+	}
+}
+
+func isResponseMessage(msg string) bool {
+	return msg == "success" || msg == "failed"
+}
+
+
+
+func Destroy() error {
+	tcpConnMutex.Lock()
+	defer tcpConnMutex.Unlock()
+
+	if stopRecvChan != nil {
+		close(stopRecvChan)
+		stopRecvChan = nil
+	}
+
+	if tcpConn != nil {
+		err := tcpConn.Close()
+		tcpConn = nil
+		isConnected = false
+		if err != nil {
+			return fmt.Errorf("failed to close connection: %v", err)
+		}
+	}
+
+	if recvChan != nil {
+		close(recvChan)
+		recvChan = nil
+	}
+
+	return nil
+}
+
+func IsConnected() bool {
+	tcpConnMutex.Lock()
+	defer tcpConnMutex.Unlock()
+	return isConnected && tcpConn != nil
+}