fix: resolve resource exhaustion with high connection counts

session/handler.go

@@ -560,37 +560,31 @@ func (s *Session) HandleForwardedConnection(conn UserConnection, sshConn *ssh.Se
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
-	var wg sync.WaitGroup
-	errChan := make(chan error, 2)
-
-	wg.Add(1)
 	go func() {
-		defer wg.Done()
 		defer func() {
 			if r := recover(); r != nil {
 				log.Printf("Panic in reader copy: %v", r)
-				errChan <- fmt.Errorf("panic: %v", r)
 			}
+			cancel()
 		}()
 
 		_, err := io.Copy(channel, conn.Reader)
 		if err != nil && !errors.Is(err, io.EOF) {
 			log.Printf("Error copying from conn.Reader to channel: %v", err)
-			errChan <- err
 		}
 		cancel()
 	}()
 
 	reader := bufio.NewReader(channel)
 
-	peekDone := make(chan error, 1)
+	peekChan := make(chan error, 1)
 	go func() {
 		_, err := reader.Peek(1)
-		peekDone <- err
+		peekChan <- err
 	}()
 
 	select {
-	case err := <-peekDone:
+	case err := <-peekChan:
 		if err == io.EOF {
 			s.sendMessage(fmt.Sprintf("\033[33m%s -> [%s] WARNING -- \"Could not forward request to the tunnel addr\"\033[0m\r\n", conn.Writer.RemoteAddr().String(), s.TunnelType))
 			sendBadGatewayResponse(conn.Writer)
@@ -613,34 +607,9 @@ func (s *Session) HandleForwardedConnection(conn UserConnection, sshConn *ssh.Se
 
 	s.sendMessage(fmt.Sprintf("\033[32m%s -> [%s] TUNNEL ADDRESS -- \"%s\"\033[0m\r\n", conn.Writer.RemoteAddr().String(), s.TunnelType, timestamp))
 
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
-		defer func() {
-			if r := recover(); r != nil {
-				log.Printf("Panic in writer copy: %v", r)
-				errChan <- fmt.Errorf("panic: %v", r)
-			}
-		}()
-
-		_, err := io.Copy(conn.Writer, reader)
-		if err != nil && !errors.Is(err, io.EOF) {
-			log.Printf("Error copying from channel to conn.Writer: %v", err)
-			errChan <- err
-		}
-		cancel()
-	}()
-
-	go func() {
-		wg.Wait()
-		close(errChan)
-	}()
-
-	for err := range errChan {
-		if err != nil {
-			log.Printf("Connection error: %v", err)
-			break
-		}
+	_, err = io.Copy(conn.Writer, reader)
+	if err != nil && !errors.Is(err, io.EOF) {
+		log.Printf("Error copying from channel to conn.Writer: %v", err)
 	}
 }