From fff746f1f8be6148acbcc70a149a1bf449384b63 Mon Sep 17 00:00:00 2001
From: David Fort <contact@hardening-consulting.com>
Date: Thu, 18 Aug 2022 09:20:51 +0200
Subject: [PATCH] shadow-server: fix state machine (#8133)

The shadow server was setting up the dynamic channel too quickly, leading
to unexpected packets during the negotiation (unexpected licence packet error
message on the client side). So let's starts dynamic channel once the activation is
done.
---
 server/shadow/shadow_client.c | 80 +++++++++++++++++------------------
 1 file changed, 38 insertions(+), 42 deletions(-)

diff --git a/server/shadow/shadow_client.c b/server/shadow/shadow_client.c
index 08781e23b..265e5a259 100644
--- a/server/shadow/shadow_client.c
+++ b/server/shadow/shadow_client.c
@@ -2196,60 +2196,56 @@ static DWORD WINAPI shadow_client_thread(LPVOID arg)
 			WLog_ERR(TAG, "Failed to check FreeRDP file descriptor");
 			goto fail;
 		}
-		else
-		{
-			if (WTSVirtualChannelManagerIsChannelJoined(client->vcm, DRDYNVC_SVC_CHANNEL_NAME))
-			{
-				switch (WTSVirtualChannelManagerGetDrdynvcState(client->vcm))
-				{
-					/* Dynamic channel status may have been changed after processing */
-					case DRDYNVC_STATE_NONE:
 
-						/* Call this routine to Initialize drdynvc channel */
-						if (!WTSVirtualChannelManagerCheckFileDescriptor(client->vcm))
+		if (client->activated &&
+		    WTSVirtualChannelManagerIsChannelJoined(client->vcm, DRDYNVC_SVC_CHANNEL_NAME))
+		{
+			switch (WTSVirtualChannelManagerGetDrdynvcState(client->vcm))
+			{
+				/* Dynamic channel status may have been changed after processing */
+				case DRDYNVC_STATE_NONE:
+
+					/* Call this routine to Initialize drdynvc channel */
+					if (!WTSVirtualChannelManagerCheckFileDescriptor(client->vcm))
+					{
+						WLog_ERR(TAG, "Failed to initialize drdynvc channel");
+						goto fail;
+					}
+
+					break;
+
+				case DRDYNVC_STATE_READY:
+					if (client->audin && !IFCALLRESULT(TRUE, client->audin->IsOpen, client->audin))
+					{
+						if (!IFCALLRESULT(FALSE, client->audin->Open, client->audin))
 						{
-							WLog_ERR(TAG, "Failed to initialize drdynvc channel");
+							WLog_ERR(TAG, "Failed to initialize audin channel");
 							goto fail;
 						}
+					}
 
-						break;
+					/* Init RDPGFX dynamic channel */
+					if (settings->SupportGraphicsPipeline && client->rdpgfx && !gfxstatus.gfxOpened)
+					{
+						client->rdpgfx->FrameAcknowledge = shadow_client_rdpgfx_frame_acknowledge;
+						client->rdpgfx->CapsAdvertise = shadow_client_rdpgfx_caps_advertise;
 
-					case DRDYNVC_STATE_READY:
-						if (client->audin &&
-						    !IFCALLRESULT(TRUE, client->audin->IsOpen, client->audin))
+						if (!client->rdpgfx->Open(client->rdpgfx))
 						{
-							if (!IFCALLRESULT(FALSE, client->audin->Open, client->audin))
-							{
-								WLog_ERR(TAG, "Failed to initialize audin channel");
-								goto fail;
-							}
+							WLog_WARN(TAG, "Failed to open GraphicsPipeline");
+							settings->SupportGraphicsPipeline = FALSE;
 						}
-
-						/* Init RDPGFX dynamic channel */
-						if (settings->SupportGraphicsPipeline && client->rdpgfx &&
-						    !gfxstatus.gfxOpened)
+						else
 						{
-							client->rdpgfx->FrameAcknowledge =
-							    shadow_client_rdpgfx_frame_acknowledge;
-							client->rdpgfx->CapsAdvertise = shadow_client_rdpgfx_caps_advertise;
-
-							if (!client->rdpgfx->Open(client->rdpgfx))
-							{
-								WLog_WARN(TAG, "Failed to open GraphicsPipeline");
-								settings->SupportGraphicsPipeline = FALSE;
-							}
-							else
-							{
-								gfxstatus.gfxOpened = TRUE;
-								WLog_INFO(TAG, "Gfx Pipeline Opened");
-							}
+							gfxstatus.gfxOpened = TRUE;
+							WLog_INFO(TAG, "Gfx Pipeline Opened");
 						}
+					}
 
-						break;
+					break;
 
-					default:
-						break;
-				}
+				default:
+					break;
 			}
 		}