rs2322tcp/internal/client/connection_test.go

/*
 * ============================================================================
 * Projekt.....: rs2322tcp
 * Datei.......: internal/client/connection_test.go
 * Copyright (C) 2026 Dieter Lang
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 * Beschreibung:
 * Tests für den Aufbau einer Verbindung zwischen einem lokalen virtuellen
 * seriellen Port und dem zugehörigen entfernten TCP-Gerät.
 *
 * Die Tests prüfen insbesondere die Auswahl des Remote-Geräts, die Erzeugung
 * des virtuellen Ports, den Aufbau der TCP-Datenverbindung und die Verbindung
 * dieser Endpunkte über eine Bridge.
 * ============================================================================
 */
package client

import (
	"net"
	"strconv"
	"strings"
	"testing"

	"git.lang-dieter.de/rs2322tcp/internal/config"
	"git.lang-dieter.de/rs2322tcp/internal/transport"
)

///////////////////////////////////////////////////////////////////////////////
// Test connection
///////////////////////////////////////////////////////////////////////////////

// testRemoteAddrConn wraps a net.Conn and provides a TCP-style remote address.
//
// net.Pipe() is used for the control connection in these tests. Its default
// RemoteAddr() is "pipe", which cannot be used by OpenDataConnection() to
// determine the server host. This wrapper supplies a normal TCP address.
type testRemoteAddrConn struct {
	net.Conn
	remoteAddr net.Addr
}

// RemoteAddr returns the TCP-style remote address configured for the test.
func (c *testRemoteAddrConn) RemoteAddr() net.Addr {
	return c.remoteAddr
}

///////////////////////////////////////////////////////////////////////////////
// Test helpers
///////////////////////////////////////////////////////////////////////////////

// startTestDataServer starts a local TCP listener for a simulated remote
// device.
//
// The listener accepts exactly one connection. The accepted connection is
// returned through the channel so the test can verify that the client has
// successfully established the data connection.
func startTestDataServer(t *testing.T) (string, <-chan net.Conn) {
	t.Helper()

	listener, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("listen for test data server: %v", err)
	}

	t.Cleanup(func() {
		_ = listener.Close()
	})

	accepted := make(chan net.Conn, 1)

	go func() {
		conn, err := listener.Accept()
		if err != nil {
			return
		}

		accepted <- conn
	}()

	return listener.Addr().String(), accepted
}

// remoteDeviceFromAddress creates a RemoteDeviceInfo whose DataPort is
// taken from the supplied local TCP address.
func remoteDeviceFromAddress(
	t *testing.T,
	id string,
	address string,
) transport.RemoteDeviceInfo {
	t.Helper()

	_, portText, err := net.SplitHostPort(address)
	if err != nil {
		t.Fatalf("split test server address %q: %v", address, err)
	}

	port, err := strconv.Atoi(portText)
	if err != nil {
		t.Fatalf("parse test server port %q: %v", portText, err)
	}

	return transport.RemoteDeviceInfo{
		ID:       id,
		Name:     id,
		DataPort: port,
	}
}

// newTestClient creates a Client whose control connection uses net.Pipe()
// but reports a normal TCP-style remote address.
func newTestClient(t *testing.T) *Client {
	t.Helper()

	controlClient, serverConn := net.Pipe()

	t.Cleanup(func() {
		_ = controlClient.Close()
		_ = serverConn.Close()
	})

	return &Client{
		conn: &testRemoteAddrConn{
			Conn: controlClient,
			remoteAddr: &net.TCPAddr{
				IP:   net.ParseIP("127.0.0.1"),
				Port: 5000,
			},
		},
	}
}

///////////////////////////////////////////////////////////////////////////////
// Tests
///////////////////////////////////////////////////////////////////////////////

func TestConnectVirtualPortNilClient(t *testing.T) {
	manager := NewVirtualPortManager(
		config.VirtualPortRangeConfig{
			First: 100,
			Last:  199,
		},
	)

	cfg := config.VirtualPortConfig{
		Port:         "/dev/ttyUSB100",
		RemoteDevice: "radio",
	}

	devices := []transport.RemoteDeviceInfo{
		{
			ID:       "radio",
			DataPort: 50123,
		},
	}

	_, _, err := connectVirtualPort(
		nil,
		manager,
		cfg,
		devices,
	)
	if err == nil {
		t.Fatal("expected error for nil client")
	}

	if !strings.Contains(err.Error(), "client is not connected") {
		t.Fatalf("unexpected error: %v", err)
	}
}

func TestConnectVirtualPortNilManager(t *testing.T) {
	cfg := config.VirtualPortConfig{
		Port:         "/dev/ttyUSB100",
		RemoteDevice: "radio",
	}

	devices := []transport.RemoteDeviceInfo{
		{
			ID:       "radio",
			DataPort: 50123,
		},
	}

	_, _, err := connectVirtualPort(
		&Client{},
		nil,
		cfg,
		devices,
	)
	if err == nil {
		t.Fatal("expected error for nil manager")
	}

	if !strings.Contains(err.Error(), "client is not connected") {
		t.Fatalf("unexpected error: %v", err)
	}
}

func TestConnectVirtualPortUnknownDevice(t *testing.T) {
	manager := NewVirtualPortManager(
		config.VirtualPortRangeConfig{
			First: 100,
			Last:  199,
		},
	)

	client := newTestClient(t)

	cfg := config.VirtualPortConfig{
		Port:         "/dev/ttyUSB100",
		RemoteDevice: "unknown",
	}

	devices := []transport.RemoteDeviceInfo{
		{
			ID:       "radio",
			DataPort: 50123,
		},
	}

	_, _, err := connectVirtualPort(
		client,
		manager,
		cfg,
		devices,
	)
	if err == nil {
		t.Fatal("expected error for unknown device")
	}

	if !strings.Contains(
		err.Error(),
		`remote device "unknown" not found`,
	) {
		t.Fatalf("unexpected error: %v", err)
	}
}

func TestConnectVirtualPortClosesPortWhenDataConnectionFails(t *testing.T) {
	manager := NewVirtualPortManager(
		config.VirtualPortRangeConfig{
			First: 100,
			Last:  100,
		},
	)

	client := newTestClient(t)

	cfg := config.VirtualPortConfig{
		Port:         "/dev/ttyUSB100",
		RemoteDevice: "radio",
	}

	devices := []transport.RemoteDeviceInfo{
		{
			ID:       "radio",
			DataPort: 1,
		},
	}

	port, conn, err := connectVirtualPort(
		client,
		manager,
		cfg,
		devices,
	)

	if err == nil {
		if conn != nil {
			_ = conn.Close()
		}

		if port != nil {
			_ = port.Close()
		}

		t.Fatal("expected data connection error")
	}

	if port != nil {
		t.Fatal(
			"virtual port must not be returned after connection failure",
		)
	}

	if conn != nil {
		t.Fatal(
			"TCP connection must not be returned after connection failure",
		)
	}

	// Port 100 must have been released after the failed connection.
	portNumber, err := manager.Reserve()
	if err != nil {
		t.Fatalf("Reserve after cleanup: %v", err)
	}

	if portNumber != 100 {
		t.Fatalf("reserved port = %d, want 100", portNumber)
	}

	manager.Release(portNumber)
}

func TestConnectVirtualPortSuccess(t *testing.T) {
	dataAddress, accepted := startTestDataServer(t)

	device := remoteDeviceFromAddress(
		t,
		"radio",
		dataAddress,
	)

	client := newTestClient(t)

	manager := NewVirtualPortManager(
		config.VirtualPortRangeConfig{
			First: 100,
			Last:  199,
		},
	)

	cfg := config.VirtualPortConfig{
		Port:         "/dev/ttyUSB100",
		RemoteDevice: "radio",
	}

	virtualPort, dataConn, err := connectVirtualPort(
		client,
		manager,
		cfg,
		[]transport.RemoteDeviceInfo{device},
	)
	if err != nil {
		t.Fatalf("connectVirtualPort: %v", err)
	}

	if virtualPort == nil {
		t.Fatal("virtual port is nil")
	}

	if dataConn == nil {
		t.Fatal("data connection is nil")
	}

	defer virtualPort.Close()
	defer dataConn.Close()

	if virtualPort.Path() != "/dev/ttyUSB100" {
		t.Fatalf(
			"virtual port path = %q, want %q",
			virtualPort.Path(),
			"/dev/ttyUSB100",
		)
	}

	// The test data server must receive the connection created by
	// OpenDataConnection().
	select {
	case conn := <-accepted:
		_ = conn.Close()

	case <-t.Context().Done():
		t.Fatal("test context cancelled while waiting for data connection")
	}
}

func TestConnectBridgeSuccess(t *testing.T) {
	dataAddress, accepted := startTestDataServer(t)

	device := remoteDeviceFromAddress(
		t,
		"radio",
		dataAddress,
	)

	client := newTestClient(t)

	manager := NewVirtualPortManager(
		config.VirtualPortRangeConfig{
			First: 100,
			Last:  199,
		},
	)

	cfg := config.VirtualPortConfig{
		Port:         "/dev/ttyUSB100",
		RemoteDevice: "radio",
	}

	bridge, virtualPort, dataConn, err := connectBridge(
		client,
		manager,
		cfg,
		[]transport.RemoteDeviceInfo{device},
	)
	if err != nil {
		t.Fatalf("connectBridge: %v", err)
	}

	if bridge == nil {
		t.Fatal("bridge is nil")
	}

	if virtualPort == nil {
		t.Fatal("virtual port is nil")
	}

	if dataConn == nil {
		t.Fatal("data connection is nil")
	}

	defer virtualPort.Close()
	defer dataConn.Close()

	if bridge.serial != virtualPort {
		t.Fatal("bridge serial endpoint does not match virtual port")
	}

	if bridge.conn != dataConn {
		t.Fatal("bridge TCP endpoint does not match data connection")
	}

	if virtualPort.Path() != "/dev/ttyUSB100" {
		t.Fatalf(
			"virtual port path = %q, want %q",
			virtualPort.Path(),
			"/dev/ttyUSB100",
		)
	}

	// The test data server must receive the TCP data connection created by
	// connectBridge().
	select {
	case conn := <-accepted:
		_ = conn.Close()

	case <-t.Context().Done():
		t.Fatal("test context cancelled while waiting for data connection")
	}
}