Fix Session 0 issue: spawn screen capture helper in user session
- CaptureModeRunner: captures desktop in user session via schtasks, sends JPEG frames over named pipe to service - RtcService: creates named pipe server, spawns helper via schtasks (same pattern as NotificationService), reads frames and forwards to WS - Program.cs: added --rdp-capture <pipeName> mode - Multi-monitor: captures all screens combined Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
@@ -1,5 +1,5 @@
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using System.Drawing;
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using System.Drawing.Imaging;
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using System.Diagnostics;
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using System.IO.Pipes;
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using System.Net.WebSockets;
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using System.Text;
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using Newtonsoft.Json;
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@@ -7,16 +7,14 @@ using Newtonsoft.Json.Linq;
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namespace ITNexusAgent.Services;
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// Überträgt den Bildschirm via JPEG-Frames über WebSocket an den Browser
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// WebSocket-Brücke: empfängt rdp_start vom Browser, spawnt Screen-Capture-Helper
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// in der User-Session (via schtasks), leitet JPEG-Frames als rdp_frame weiter
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public class RtcService
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{
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private readonly string _serverUrl;
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private readonly string _agentKey;
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private readonly string _hostname;
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private static readonly ImageCodecInfo JpegCodec =
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ImageCodecInfo.GetImageEncoders().First(c => c.FormatID == ImageFormat.Jpeg.Guid);
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public RtcService(string serverUrl, string agentKey, string hostname)
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{
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_serverUrl = serverUrl;
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@@ -67,7 +65,7 @@ public class RtcService
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if (type == "rdp_start" && captureCts == null)
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{
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captureCts = CancellationTokenSource.CreateLinkedTokenSource(ct);
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_ = CaptureLoopAsync(ws, captureCts.Token);
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_ = CapturePipeLoopAsync(ws, captureCts.Token);
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AgentWorker.Log("RDP: Screen-Capture gestartet");
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}
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else if (type == "rdp_stop" && captureCts != null)
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@@ -82,46 +80,131 @@ public class RtcService
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AgentWorker.Log("RDP: Getrennt");
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}
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private static async Task CaptureLoopAsync(ClientWebSocket ws, CancellationToken ct)
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private async Task CapturePipeLoopAsync(ClientWebSocket ws, CancellationToken ct)
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{
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var encParams = new EncoderParameters(1);
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encParams.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 60L);
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var pipeName = $"it-nexus-rdp-{Guid.NewGuid():N}";
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var exePath = System.Diagnostics.Process.GetCurrentProcess().MainModule!.FileName;
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while (!ct.IsCancellationRequested && ws.State == WebSocketState.Open)
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using var pipeServer = new NamedPipeServerStream(
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pipeName, PipeDirection.In, 1,
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PipeTransmissionMode.Byte, PipeOptions.Asynchronous);
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// Helper via schtasks in User-Session starten
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if (!SpawnCaptureHelper(exePath, pipeName))
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{
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AgentWorker.Log("RDP: Helper-Start fehlgeschlagen");
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return;
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}
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try
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{
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using var connectCts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
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using var linked = CancellationTokenSource.CreateLinkedTokenSource(ct, connectCts.Token);
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await pipeServer.WaitForConnectionAsync(linked.Token);
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}
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catch
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{
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AgentWorker.Log("RDP: Helper hat sich nicht verbunden");
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return;
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}
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AgentWorker.Log("RDP: Helper verbunden, sende Frames...");
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var lenBuf = new byte[4];
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while (!ct.IsCancellationRequested && pipeServer.IsConnected && ws.State == WebSocketState.Open)
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{
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try
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{
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var screen = System.Windows.Forms.Screen.PrimaryScreen;
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if (screen == null) { await Task.Delay(500, ct).ContinueWith(_ => { }); continue; }
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var bounds = screen.Bounds;
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using var bmp = new Bitmap(bounds.Width, bounds.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
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using (var g = Graphics.FromImage(bmp))
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g.CopyFromScreen(bounds.X, bounds.Y, 0, 0, bounds.Size);
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byte[] jpeg;
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using (var ms = new MemoryStream())
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// 4-Byte Länge lesen
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var read = 0;
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while (read < 4)
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{
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bmp.Save(ms, JpegCodec, encParams);
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jpeg = ms.ToArray();
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var n = await pipeServer.ReadAsync(lenBuf.AsMemory(read, 4 - read), ct);
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if (n == 0) goto done;
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read += n;
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}
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var jpegLen = BitConverter.ToInt32(lenBuf);
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if (jpegLen <= 0 || jpegLen > 5_000_000) continue;
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// JPEG-Daten lesen
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var jpeg = new byte[jpegLen];
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read = 0;
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while (read < jpegLen)
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{
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var n = await pipeServer.ReadAsync(jpeg.AsMemory(read, jpegLen - read), ct);
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if (n == 0) goto done;
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read += n;
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}
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var payload = Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(new
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{
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type = "rdp_frame",
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data = Convert.ToBase64String(jpeg),
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w = bounds.Width,
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h = bounds.Height
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data = Convert.ToBase64String(jpeg)
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}));
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if (ws.State == WebSocketState.Open)
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await ws.SendAsync(new ArraySegment<byte>(payload), WebSocketMessageType.Text, true, CancellationToken.None);
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}
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catch (OperationCanceledException) { break; }
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catch (Exception ex) { AgentWorker.Log($"RDP: Capture-Fehler: {ex.Message}"); }
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catch (Exception ex) { AgentWorker.Log($"RDP: Pipe-Fehler: {ex.Message}"); break; }
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}
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// ~8 fps
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await Task.Delay(125, ct).ContinueWith(_ => { });
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done:
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AgentWorker.Log("RDP: Frame-Loop beendet");
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}
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private static bool SpawnCaptureHelper(string exePath, string pipeName)
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{
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try
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{
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var fullUser = NotificationService.GetLoggedOnUser();
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if (string.IsNullOrEmpty(fullUser))
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{
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AgentWorker.Log("RDP: Kein eingeloggter User gefunden");
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return false;
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}
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var taskName = $"ITNexus-RDP-{pipeName[^8..]}";
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Process.Start(new ProcessStartInfo("schtasks.exe", $"/delete /tn \"{taskName}\" /f")
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{ CreateNoWindow = true })?.WaitForExit();
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var triggerTime = DateTime.Now.AddMinutes(60).ToString("HH:mm:ss");
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var ruArg = fullUser.StartsWith("AzureAD\\", StringComparison.OrdinalIgnoreCase)
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? "/ru \"INTERACTIVE\""
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: $"/ru \"{fullUser}\"";
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var args = $"/create /tn \"{taskName}\" /tr \"\\\"{exePath}\\\" --rdp-capture {pipeName}\" " +
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$"/sc ONCE /st {triggerTime} {ruArg} /it /f";
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var p = Process.Start(new ProcessStartInfo("schtasks.exe", args)
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{ CreateNoWindow = true, RedirectStandardError = true, UseShellExecute = false });
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p?.WaitForExit();
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if (p?.ExitCode != 0)
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{
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AgentWorker.Log($"RDP: schtasks create fehlgeschlagen (ExitCode={p?.ExitCode})");
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return false;
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}
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Process.Start(new ProcessStartInfo("schtasks.exe", $"/run /tn \"{taskName}\"")
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{ CreateNoWindow = true })?.WaitForExit();
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// Aufräumen nach kurzer Zeit
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_ = Task.Run(async () =>
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{
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await Task.Delay(5000);
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Process.Start(new ProcessStartInfo("schtasks.exe", $"/delete /tn \"{taskName}\" /f")
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{ CreateNoWindow = true })?.WaitForExit();
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});
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AgentWorker.Log($"RDP: Helper gestartet als '{fullUser}' (Task: {taskName})");
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return true;
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}
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catch (Exception ex)
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{
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AgentWorker.Log($"RDP: SpawnHelper Fehler: {ex.Message}");
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return false;
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}
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}
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}
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