core: allow ms android client protocol violation

According to [MS-RDPBCGR 2.2.1.11.1.1.1] the TS_EXTENDED_INFO_PACKET
structure's cbClientDir field must include the _mandatory_ NULL
terminator of the ClientDir field.
However, since version 8.1.31.44, the Microsoft Remote Desktop Client
for Android sets cbClientDir to 0.

diff --git a/libfreerdp/core/info.c b/libfreerdp/core/info.c
index 57d1894..923f88a 100644 (file)
--- a/libfreerdp/core/info.c
+++ b/libfreerdp/core/info.c
@@ -249,10 +249,13 @@ BOOL rdp_read_extended_info_packet(rdpRdp* rdp, wStream* s)
 
        /* cbClientDir is the size in bytes of the character data in the clientDir field.
         * This size includes the length of the mandatory null terminator.
-        * The maximum allowed value is 512 bytes
+        * The maximum allowed value is 512 bytes.
+        * Note: Although according to [MS-RDPBCGR 2.2.1.11.1.1.1] the null terminator
+        * is mandatory the Microsoft Android client (starting with version 8.1.31.44)
+        * sets cbClientDir to 0.
         */
 
-       if ((cbClientDir % 2) || cbClientDir < 2 || cbClientDir > 512)
+       if ((cbClientDir % 2) || cbClientDir > 512)
        {
                WLog_ERR(TAG, "protocol error: invalid cbClientDir value: %u", cbClientDir);
                return FALSE;
@@ -267,18 +270,22 @@ BOOL rdp_read_extended_info_packet(rdpRdp* rdp, wStream* s)
                settings->ClientDir = NULL;
        }
 
-       wstr = (WCHAR*) Stream_Pointer(s);
-       if (wstr[cbClientDir / 2 - 1])
-       {
-               WLog_ERR(TAG, "protocol error: clientDir must be null terminated");
-               return FALSE;
-       }
-       if (ConvertFromUnicode(CP_UTF8, 0, (WCHAR*) Stream_Pointer(s), -1, &settings->ClientDir, 0, NULL, NULL) < 1)
+       if (cbClientDir)
        {
-               WLog_ERR(TAG, "failed to convert client directory");
-               return FALSE;
+               wstr = (WCHAR*) Stream_Pointer(s);
+               if (wstr[cbClientDir / 2 - 1])
+               {
+                       WLog_ERR(TAG, "protocol error: clientDir must be null terminated");
+                       return FALSE;
+               }
+               if (ConvertFromUnicode(CP_UTF8, 0, (WCHAR*) Stream_Pointer(s), -1, &settings->ClientDir, 0, NULL, NULL) < 1)
+               {
+                       WLog_ERR(TAG, "failed to convert client directory");
+                       return FALSE;
+               }
+               Stream_Seek(s, cbClientDir);
+               WLog_DBG(TAG, "rdp client dir: [%s]", settings->ClientDir);
        }
-       Stream_Seek(s, cbClientDir);
 
        if (!rdp_read_client_time_zone(s, settings))
                return FALSE;