Handle freeing ports correctly

main.go

@@ -364,13 +364,6 @@ func parseTargetData(data interface{}) (TargetData, error) {
 }
 
 func updateTargets(pm *proxy.ProxyManager, action string, tunnelIP string, proto string, targetData TargetData) error {
-
-	// Stop the proxy manager before adding new targets
-	err := pm.Stop()
-	if err != nil {
-		logger.Error("Failed to stop proxy manager: %v", err)
-	}
-
 	for _, t := range targetData.Targets {
 		// Split the first number off of the target with : separator and use as the port
 		parts := strings.Split(t, ":")
@@ -389,18 +382,34 @@ func updateTargets(pm *proxy.ProxyManager, action string, tunnelIP string, proto
 
 		if action == "add" {
 			target := parts[1] + ":" + parts[2]
-			pm.RemoveTarget(proto, tunnelIP, port) // remove it first in case this is an update. we are kind of using the internal port as the "targetId" in the proxy
+			// Only remove the specific target if it exists
+			err := pm.RemoveTarget(proto, tunnelIP, port)
+			if err != nil {
+				// Ignore "target not found" errors as this is expected for new targets
+				if !strings.Contains(err.Error(), "target not found") {
+					logger.Error("Failed to remove existing target: %v", err)
+				}
+			}
+
+			// Add the new target
 			pm.AddTarget(proto, tunnelIP, port, target)
+
+			// Start just this target by calling Start() on the proxy manager
+			// The Start() function is idempotent and will only start new targets
+			err = pm.Start()
+			if err != nil {
+				logger.Error("Failed to start proxy manager after adding target: %v", err)
+				return err
+			}
 		} else if action == "remove" {
 			logger.Info("Removing target with port %d", port)
-			pm.RemoveTarget(proto, tunnelIP, port)
+			err := pm.RemoveTarget(proto, tunnelIP, port)
+			if err != nil {
+				logger.Error("Failed to remove target: %v", err)
+				return err
+			}
 		}
 	}
 
-	err = pm.Start()
-	if err != nil {
-		logger.Error("Failed to start proxy manager: %v", err)
-	}
-
 	return nil
 }

proxy/manager.go

@@ -7,6 +7,7 @@ import (
 	"net"
 	"strings"
 	"sync"
+	"time"
 
 	"golang.zx2c4.com/wireguard/tun/netstack"
 )
@@ -27,6 +28,7 @@ func (pm *ProxyManager) AddTarget(protocol, listen string, port int, target stri
 		Port:     port,
 		Target:   target,
 		cancel:   make(chan struct{}),
+		done:     make(chan struct{}),
 	}
 
 	pm.targets = append(pm.targets, newTarget)
@@ -45,23 +47,42 @@ func (pm *ProxyManager) RemoveTarget(protocol, listen string, port int) error {
 		if target.Listen == listen &&
 			target.Port == port &&
 			strings.ToLower(target.Protocol) == protocol {
+
 			// Signal the serving goroutine to stop
-			// close(target.cancel)
+			select {
+			case <-target.cancel:
+				// Channel is already closed, no need to close it again
+			default:
+				close(target.cancel)
+			}
 
 			// Close the appropriate listener/connection based on protocol
 			target.Lock()
 			switch protocol {
 			case "tcp":
 				if target.listener != nil {
-					target.listener.Close()
+					select {
+					case <-target.cancel:
+						// Listener was already closed by Stop()
+					default:
+						target.listener.Close()
+					}
 				}
 			case "udp":
 				if target.udpConn != nil {
-					target.udpConn.Close()
+					select {
+					case <-target.cancel:
+						// Connection was already closed by Stop()
+					default:
+						target.udpConn.Close()
+					}
 				}
 			}
 			target.Unlock()
 
+			// Wait for the target to fully stop
+			<-target.done
+
 			// Remove the target from the slice
 			pm.targets = append(pm.targets[:i], pm.targets[i+1:]...)
 			return nil
@@ -76,7 +97,16 @@ func (pm *ProxyManager) Start() error {
 	defer pm.RUnlock()
 
 	for i := range pm.targets {
-		target := &pm.targets[i] // Use pointer to modify the target in the slice
+		target := &pm.targets[i]
+
+		// Skip already running targets
+		target.Lock()
+		if target.listener != nil || target.udpConn != nil {
+			target.Unlock()
+			continue
+		}
+		target.Unlock()
+
 		switch strings.ToLower(target.Protocol) {
 		case "tcp":
 			go pm.serveTCP(target)
@@ -93,27 +123,36 @@ func (pm *ProxyManager) Stop() error {
 	pm.Lock()
 	defer pm.Unlock()
 
+	var wg sync.WaitGroup
 	for i := range pm.targets {
 		target := &pm.targets[i]
-		close(target.cancel)
-		target.Lock()
-		if target.listener != nil {
-			target.listener.Close()
-		}
-		if target.udpConn != nil {
-			target.udpConn.Close()
-		}
-		target.Unlock()
+		wg.Add(1)
+		go func(t *ProxyTarget) {
+			defer wg.Done()
+			close(t.cancel)
+			t.Lock()
+			if t.listener != nil {
+				t.listener.Close()
+			}
+			if t.udpConn != nil {
+				t.udpConn.Close()
+			}
+			t.Unlock()
+			// Wait for the target to fully stop
+			<-t.done
+		}(target)
 	}
+	wg.Wait()
 	return nil
 }
 
 func (pm *ProxyManager) serveTCP(target *ProxyTarget) {
+	defer close(target.done) // Signal that this target is fully stopped
+
 	listener, err := pm.tnet.ListenTCP(&net.TCPAddr{
 		IP:   net.ParseIP(target.Listen),
 		Port: target.Port,
 	})
-	log.Printf("Listening on %s:%d", target.Listen, target.Port)
 	if err != nil {
 		log.Printf("Failed to start TCP listener for %s:%d: %v", target.Listen, target.Port, err)
 		return
@@ -126,14 +165,13 @@ func (pm *ProxyManager) serveTCP(target *ProxyTarget) {
 	defer listener.Close()
 	log.Printf("TCP proxy listening on %s", listener.Addr())
 
-	// Channel to signal active connections to close
-	done := make(chan struct{})
 	var activeConns sync.WaitGroup
+	acceptDone := make(chan struct{})
 
 	// Goroutine to handle shutdown signal
 	go func() {
 		<-target.cancel
-		close(done)
+		close(acceptDone)
 		listener.Close()
 	}()
 
@@ -147,6 +185,8 @@ func (pm *ProxyManager) serveTCP(target *ProxyTarget) {
 				return
 			default:
 				log.Printf("Failed to accept TCP connection: %v", err)
+				// Don't return here, try to accept new connections
+				time.Sleep(time.Second)
 				continue
 			}
 		}
@@ -154,7 +194,7 @@ func (pm *ProxyManager) serveTCP(target *ProxyTarget) {
 		activeConns.Add(1)
 		go func() {
 			defer activeConns.Done()
-			pm.handleTCPConnection(conn, target.Target, done)
+			pm.handleTCPConnection(conn, target.Target, acceptDone)
 		}()
 	}
 }
@@ -198,6 +238,8 @@ func (pm *ProxyManager) handleTCPConnection(clientConn net.Conn, target string,
 }
 
 func (pm *ProxyManager) serveUDP(target *ProxyTarget) {
+	defer close(target.done) // Signal that this target is fully stopped
+
 	addr := &net.UDPAddr{
 		IP:   net.ParseIP(target.Listen),
 		Port: target.Port,
@@ -217,16 +259,19 @@ func (pm *ProxyManager) serveUDP(target *ProxyTarget) {
 	log.Printf("UDP proxy listening on %s", conn.LocalAddr())
 
 	buffer := make([]byte, 65535)
+	var activeConns sync.WaitGroup
 
 	for {
 		select {
 		case <-target.cancel:
+			activeConns.Wait() // Wait for all active UDP handlers to complete
 			return
 		default:
 			n, remoteAddr, err := conn.ReadFrom(buffer)
 			if err != nil {
 				select {
 				case <-target.cancel:
+					activeConns.Wait()
 					return
 				default:
 					log.Printf("Failed to read UDP packet: %v", err)
@@ -240,7 +285,9 @@ func (pm *ProxyManager) serveUDP(target *ProxyTarget) {
 				continue
 			}
 
+			activeConns.Add(1)
 			go func(data []byte, remote net.Addr) {
+				defer activeConns.Done()
 				targetConn, err := net.DialUDP("udp", nil, targetAddr)
 				if err != nil {
 					log.Printf("Failed to connect to target %s: %v", target.Target, err)

proxy/types.go

@@ -14,9 +14,10 @@ type ProxyTarget struct {
 	Port       int
 	Target     string
 	cancel     chan struct{}  // Channel to signal shutdown
+	done       chan struct{}  // Channel to signal completion
 	listener   net.Listener   // For TCP
 	udpConn    net.PacketConn // For UDP
-	sync.Mutex                // Protect access to connections
+	sync.Mutex                // Protect access to connection
 }
 
 type ProxyManager struct {