Sebastian Ohmsen created GUACAMOLE-349:
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Summary: Currupt user input for guacamole sessions over RDP
Key: GUACAMOLE-349
URL: https://issues.apache.org/jira/browse/GUACAMOLE-349
Project: Guacamole
Issue Type: Bug
Components: guacamole, RDP
Reporter: Sebastian Ohmsen
We've come across a bug that is corrupting the user input for guacamole
sessions over rdp. The problem only occurs when you open a RDP session inside
the RDP session established by guacamole. Our use case is that we connect to a
Hyper-V server and would open the console of a VM running on it. You can very
well test that too with connecting to any RDP server from the connection
established by guacamole.
We've tested this extensively and we can observe the following: Whenever you
press a key combination that produces another result by adding a modifier key,
like "SHIFT_R + ."(dot) which should lead to an ">" sign, it's only a matter of
time when this is mapped to a "."(dot) sign. This does not only occur when you
hold both keys down, it also occurs occasionally when you press it the first
time. This makes entering passwords super hard and seems to be a bug.
We've traced it down to the corresponding C code and think the problem is here:
https://github.com/apache/incubator-guacamole-server/blob/master/src/protocols/rdp/keyboard.c#L261
In some cases of extra mapped keys, for example in the above case, it's sending
more keys than expected. We can see that “SHIFT_L + .” results in following
keysym updates:
* FFE1 (SHIFT_R) pressed
* 003E (>) pressed
* 003E (>) released
* FFE1 (SHIFT_R) released
and works perfectly fine. In contrast “SHIFT_R + .” results in following events:
* FFE2 (SHIFT_R) pressed
* FFE1 (SHIFT_L) pressed
* 003E (>) pressed
* FFE1 (SHIFT_L) released
* FFE1 (SHIFT_L) pressed
* 003E (>) released
* FFE1 (SHIFT_L) released
* FFE2 (SHIFT_R) released
which leads to the described behavior above.
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