From f6f4acc9215e62c936d643d6a6b9ddbba997652e Mon Sep 17 00:00:00 2001
From: Steve Pronovost <spronovo@microsoft.com>
Date: Sat, 16 Oct 2021 11:55:46 -0700
Subject: [PATCH] Added support for AUDIO_PLAYBACK_DVC

Support audio on dynamic channel. Please refer to MS-RDPEA.
---
 channels/rdpsnd/server/rdpsnd_main.c | 37 ++++++++++++++++++++++++----
 channels/rdpsnd/server/rdpsnd_main.h |  1 +
 include/freerdp/server/rdpsnd.h      |  3 +++
 3 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/channels/rdpsnd/server/rdpsnd_main.c b/channels/rdpsnd/server/rdpsnd_main.c
index 615a5627a..6f01b47fa 100644
--- a/channels/rdpsnd/server/rdpsnd_main.c
+++ b/channels/rdpsnd/server/rdpsnd_main.c
@@ -673,13 +673,40 @@ static UINT rdpsnd_server_start(RdpsndServerContext* context)
 	DWORD bytesReturned;
 	RdpsndServerPrivate* priv = context->priv;
 	UINT error = ERROR_INTERNAL_ERROR;
-	priv->ChannelHandle =
-	    WTSVirtualChannelOpen(context->vcm, WTS_CURRENT_SESSION, RDPSND_CHANNEL_NAME);
+	PULONG pSessionId = NULL;
 
-	if (!priv->ChannelHandle)
+	priv->SessionId = WTS_CURRENT_SESSION;
+
+	if (context->use_dynamic_virtual_channel)
 	{
-		WLog_ERR(TAG, "WTSVirtualChannelOpen failed!");
-		return ERROR_INTERNAL_ERROR;
+		if (WTSQuerySessionInformationA(context->vcm, WTS_CURRENT_SESSION, WTSSessionId,
+		                                (LPSTR*)&pSessionId, &bytesReturned))
+		{
+			priv->SessionId = (DWORD)*pSessionId;
+			WTSFreeMemory(pSessionId);
+			priv->ChannelHandle = (HANDLE)WTSVirtualChannelOpenEx(
+			    priv->SessionId, "AUDIO_PLAYBACK_DVC", WTS_CHANNEL_OPTION_DYNAMIC);
+			if (!priv->ChannelHandle)
+			{
+				WLog_ERR(TAG, "Open audio dynamic virtual channel (AUDIO_PLAYBACK_DVC) failed!");
+				return ERROR_INTERNAL_ERROR;
+			}
+		}
+		else
+		{
+			WLog_ERR(TAG, "WTSQuerySessionInformationA failed!");
+			return ERROR_INTERNAL_ERROR;
+		}
+	}
+	else
+	{
+		priv->ChannelHandle =
+		    WTSVirtualChannelOpen(context->vcm, WTS_CURRENT_SESSION, RDPSND_CHANNEL_NAME);
+		if (!priv->ChannelHandle)
+		{
+			WLog_ERR(TAG, "Open audio static virtual channel (rdpsnd) failed!");
+			return ERROR_INTERNAL_ERROR;
+		}
 	}
 
 	if (!WTSVirtualChannelQuery(priv->ChannelHandle, WTSVirtualEventHandle, &buffer,
diff --git a/channels/rdpsnd/server/rdpsnd_main.h b/channels/rdpsnd/server/rdpsnd_main.h
index 69923996f..149adbb13 100644
--- a/channels/rdpsnd/server/rdpsnd_main.h
+++ b/channels/rdpsnd/server/rdpsnd_main.h
@@ -39,6 +39,7 @@ struct _rdpsnd_server_private
 	HANDLE StopEvent;
 	HANDLE channelEvent;
 	void* ChannelHandle;
+	DWORD SessionId;
 
 	BOOL waitingHeader;
 	DWORD expectedBytes;
diff --git a/include/freerdp/server/rdpsnd.h b/include/freerdp/server/rdpsnd.h
index 302e23e9a..b73e2a865 100644
--- a/include/freerdp/server/rdpsnd.h
+++ b/include/freerdp/server/rdpsnd.h
@@ -56,6 +56,9 @@ struct _rdpsnd_server_context
 	/* Server self-defined pointer. */
 	void* data;
 
+	/* Server to request to use dynamic virtual channel. */
+	BOOL use_dynamic_virtual_channel;
+
 	/* Server supported formats. Set by server. */
 	AUDIO_FORMAT* server_formats;
 	size_t num_server_formats;