FreeRDP version 2.0.0-rc0 and older will automatically free whatever
entry_points->pInterface is set to when the channel plugin is unloaded.
This doesn't happen in later versions, but will result in a double-free
upon disconnect for 2.0.0-rc0 in our case. As we don't need pInterface,
we can safely set this to NULL and avoid the issue entirely.
In FreeRDP 2.0.0-rc0 and earlier, Bitmap_Free(bitmap) invokes the free
handler of the given bitmap, frees bitmap->data, and then frees the
bitmap. The implementation-specific free handler needs to be aware only
of the implementation's own concerns.
After FreeRDP 2.0.0-rc0, Bitmap_Free(bitmap) only invokes the
implementation-specific free handler, and it's on the implementation to
know that bitmap->data must be manually freed with _aligned_free() and
bitmap must be freed with free(). The implementation-specific free
handler must be aware of the internals of the library.
See commit 8dda26a.
On some platforms, the libguacai-client.so plugin for FreeRDP reports an
unlinked symbol:
undefined symbol: guac_freerdp_dynamic_channel_collection_add (/usr/local/lib/freerdp2/libguacai-client.so)
This symbol is actually unused within the plugin, but may be referenced
due to being defined within a function in a common piece of source
shared between the plugin and the RDP support.
Separating the actual common components such that they can be included
by both the RDP support and the libguacai-client.so plugin removes the
potential for unused pieces being flagged as missing.
Without a typecast, errors like the following are generated by the
compiler:
channels/cliprdr.c: In function 'guac_rdp_cliprdr_channel_connected':
channels/cliprdr.c:477:27: error: assignment from incompatible pointer type [-Werror]
cliprdr->MonitorReady = guac_rdp_cliprdr_monitor_ready;
^
channels/cliprdr.c:478:31: error: assignment from incompatible pointer type [-Werror]
cliprdr->ServerFormatList = guac_rdp_cliprdr_format_list;
^
channels/cliprdr.c:479:38: error: assignment from incompatible pointer type [-Werror]
cliprdr->ServerFormatDataRequest = guac_rdp_cliprdr_format_data_request;
^
channels/cliprdr.c:480:39: error: assignment from incompatible pointer type [-Werror]
cliprdr->ServerFormatDataResponse = guac_rdp_cliprdr_format_data_response;
^
cc1: all warnings being treated as errors
This is because FreeRDP commit 65812bd added const to the pointer
argument of each of these handlers, wheras older versions of FreeRDP
lack const here. Our implementations of these functions declare const
and thus do not match the older prototype, though they are compatible
with it.
The latter expects color input to be in an intermediate representation
resulting from using ReadColor(), and produces color output which cannot
be used until converted back with WriteColor().
We set the values within the OrderSupport array to match which RDP
messages we have implemented within guac_rdp_push_settings(). This array
is reset to its default values prior to the preconnect handler being
invoked, thus guac_rdp_push_settings() MUST be invoked within the
preconnect handler for its settings to have the intended effect.
Without proper values within OrderSupport, the initial RDP negotiation
process will claim support for messages that we don't actually support,
resulting in graphical artifacts and unexpected behavior.
