The VirtualChannelChunkSize setting refers to the VCChunkSize for static
channels and not to the maximum size for DVC data PDUs.
DVC data PDUs are according to [MS-RDPEDYC] always limited to 1600
Bytes.
When a FreeRDP-based server tried to open a DVC, but the client answered
the DVC create request with a negative CreationStatus in the DVC create
response PDU, the server can then assume that no actual PDUs can be
received for that channel.
However, as long as the channel handle exists, FreeRDP happily forwards
any potential PDU for that handle disregarding the CreationStatus.
This is problematic, since the channel handling usually runs in its own
thread and as a result, the channel may not be destructed yet, when
receiving such stray PDU.
The PDU may be processed, even though it is not expected to be.
A situation, where this becomes problematic is the AUDIO_PLAYBACK_DVC
channel.
It may be the case, that the client answered the DVC create request
with a negative result, the server may try to close the handle and open
the static channel (RDPSND) instead, but before the server can close the
channel handle, the client actually sends PDUs regarding the format
negotiation.
In this case, the server may unintentionally already set things up,
which was not desired (the DVC is about to be closed anyway).
While this specific situation is hypothetical, since it would depend on
a malicious client, it is still possible to happen, especially since the
server implementation does not invoke the format negotiation, but
FreeRDP does it automatically, as soon as the DVC create request is
sent.
Fix this issue by discarding any data PDUs (DYNVC_DATA_FIRST and
DYNVC_DATA) of channels, that were not opened successfully.
With all calls when WTSVirtualChannelQuery returns FALSE that means that
no ppBuffer was allocated, that was not the case with class=WTSVirtualChannelReady.
Most callers were not aware of that, leading to leaks for example when the channel is
not available client-side, the patch changes that so that you have to call call WTSFreeMemory
only if WTSVirtualChannelQuery returned TRUE.
This allows server implementations to add handling for situations,
where the client side does not support them.
Particularly useful for the audio output channels (static channel as
fallback, when dynamic channel is not supported).
* Fixed remdesk settings pointer
* Fixed sign warnings in display_write_monitor_layout_pdu
* Use freerdp_abort_connect_context and freerdp_shall_disconnect_context
* Added and updates settings
* info assert/dynamic timezone
* mcs assert/log/flags
* Fixed and added assertions for wStream
* Unified stream length checks
* Added new function to check for lenght and log
* Replace all usages with this new function
* Cleaned up PER, added parser logging
* Cleaned up BER, added parser logging
* log messages
* Modified Stream_CheckAndLogRequiredLengthEx
* Allow custom format and options
* Add Stream_CheckAndLogRequiredLengthExVa for prepared va_list
* Improved Stream_CheckAndLogRequiredLength
* Now have log level adjustable
* Added function equivalents for existing logger
* Added a backtrace in case of a failure is detected
* Fixed public API input checks
* Use freerdp_settings_* for shadow and sample server
* Added freerdp_peer_set_local_and_hostname
* Code cleanups and WINPR_ASSERT
* Code cleanups
* Use CHANNEL_NAME_LEN where appropriate
* Use temporary variables in loop instead of direct array access
* Fix some missing argument checks for function pointer implementations
* Fix broken return value check for client->SendChannelData
* Updated const correctness for function pointer implementations
TPKT header length and consumption of data was not consistently
checked. This adds checks after each packet processed and fixes
any inconsistencies found.
