Re: [DISCUSS] Add FAQ to website (Was: Re: Seamless Clipboard Redirection from Local to Remote Desktop)

[Nick Couchman]

+1 - Great idea, let's do it.  I'll have to think about whether there are
other questions that should be added, but I like the idea and think the
list here is a great start.

-Nick

On Sun, Jan 14, 2018 at 3:37 PM, Mike Jumper 
wrote:

> Hello all,
>
> With the frequency that questions like the forwarded email below are
> asked, I think we should look to adding an up-to-date FAQ on the website
> (not within the manual) which covers these questions/issues.
>
> So far, the following come to mind:
>
> * Something fundamental to Guacamole isn't working for me. Where do I
> report this? (Remember that guac is used by many others without issue, and
> the more fundamental a problem is, the less likely it's a bug -
> troubleshooting steps, check the logs, failing that ask on the mailing
> lists.)
>
> * I have set things up successfully, however if i try [X], instead of [Y]
> happening as documented, [Z] happens. Where should I report this? (JIRA)
>
> * I have found an issue which may have security implications. Where should
> I report this? (private@)
>
> * Why don't you just use the clipboard directly instead of the box in the
> menu? (JavaScript cannot access the clipboard directly for security reasons)
>
> * I see the browser has "copy" and "paste" events. Why don't you handle
> these events so clipboard works? (Doing so is actually varying combinations
> of impossible and unreliable, and ultimately results in confusion.)
>
> * I press [keyboard shortcut] but it's handled by my browser or operating
> system instead of the remote desktop. Can you fix this? (No, guac already
> attempts to handle all keyboard events, and can't control whether your
> browser or operating system reserve some keyboard shortcuts for their own
> use.)
>
> * I need to share files on my computer with the remote desktop. I see
> Guacamole has drive redirection support, but only for files accessible to
> the Guacamole server. How can I share local files? (This is not possible,
> JavaScript cannot access local files directly in this way.)
>
> * I want to print to my local printer. I see Guacamole has printing
> support, but this produces a PDF download. How do I print directly to my
> local printers? (This is not possible, JavaScript cannot access local
> printers. It is possible to cause the PDF to automatically open a print
> dialog, and on some browsers it is also possible to automatically open the
> PDF, but currently this does not actually work reliably across all
> platforms and whether it will work cannot be detected.)
>
> * Can you add support for X11 forwarding to SSH? (No, this wouldn't
> actually work well in practice, but there is an X.Org driver being written)
>
> * I'm trying to connect to my remote desktop by it isn't working. Why?
> (troubleshooting procedures, how to check the logs)
>
> * I am using an application within the remote desktop under Guacamole, but
> the application isn't working correctly. Can you fix Guacamole so it
> doesn't break my application? (it isn't)
>
> * When I connect via RDP, the screen size is set correctly, but it does
> not update if I resize the browser window. Why?
>
> * When I connect via VNC, the screen size is not set correctly. It remains
> the same regardless of the browser window's size. Why?
>
> * I want to do [Y] in order to accomplish [X]. How do I do [Y] with
> Guacamole? (Rather than assume Y is the correct approach, instead look into
> how to do X with Guacamole - see "the xy problem")
>
> Any thoughts/suggestions?
>
> - Mike
>
> On Sun, Jan 14, 2018 at 1:16 AM, Mike Jumper 
> wrote:
>
>> On Fri, Jan 12, 2018 at 6:25 AM, Amarjeet Singh 
>> wrote:
>>
>>> ...
>>>
>>> 1. After more debugging I have noticed that these functions take lot of
>>> time to process if buffer size if large ( copying or pasting large amount
>>> of data ).
>>>
>>>
>>>1.
>>> *__encode_utf8 *
>>>2.
>>> *__append_utf8 *
>>>3.
>>> *array_writer.sendData(__encode_utf8(text)); *
>>>4. *__decode_utf8*
>>>
>>>
>> Can you elaborate here? What leads you to the conclusion that encoding
>> things to UTF-8 is taking significant processing time?
>>
>> 2. There are many function in Guacamole Javascript which are independent
>>> of user interface elements, such as the DOM and common JS functions like
>>> getElementById where we can use Webworker to improve the performance of
>>> Guacamole.
>>>
>>
>> Again, can you elaborate? What specifically do you believe would be
>> improved through the use of WebWorkers? Have you tried making this change
>> yourself and observed significant improvement?
>>
>> 3. On Paste event we can get the data from the Local Clipboard and send
>>> it to the Remote Server so that Remote server also synced with the Local
>>> Server == And then send the Ctrl + V keys to paste the CLipboard data.
>>>
>>
>> The browser will only fire the "paste" event under very strict
>> circumstances. What you describe can work, but 

Re: Seamless Clipboard Redirection from Local to Remote Desktop

[Mike Jumper]

On Fri, Jan 12, 2018 at 6:25 AM, Amarjeet Singh 
wrote:

> ...
>
> 1. After more debugging I have noticed that these functions take lot of
> time to process if buffer size if large ( copying or pasting large amount
> of data ).
>
>
>1.
> *__encode_utf8 *
>2.
> *__append_utf8 *
>3.
> *array_writer.sendData(__encode_utf8(text)); *
>4. *__decode_utf8*
>
>
Can you elaborate here? What leads you to the conclusion that encoding
things to UTF-8 is taking significant processing time?

2. There are many function in Guacamole Javascript which are independent of
> user interface elements, such as the DOM and common JS functions like
> getElementById where we can use Webworker to improve the performance of
> Guacamole.
>

Again, can you elaborate? What specifically do you believe would be
improved through the use of WebWorkers? Have you tried making this change
yourself and observed significant improvement?

3. On Paste event we can get the data from the Local Clipboard and send it
> to the Remote Server so that Remote server also synced with the Local
> Server == And then send the Ctrl + V keys to paste the CLipboard data.
>

The browser will only fire the "paste" event under very strict
circumstances. What you describe can work, but you will run into
difficulties with:

* Differences among platforms between the keys pressed locally vs. remotely
for pasting clipboard data (not all platforms use Ctrl+V, and even on
platforms which typically use Ctrl+V, not all applications will do so)
* The need to allow some key events through to the browser so that keyboard
events blossom into actual clipboard events, yet still somehow take control
of those events to the extent that they can be sent to the remote desktop
unmodified if they do not actually deal with clipboard after all.

This was actually tried in the past, years ago, in much older releases of
Guacamole. The changes were ultimately removed because they proved too
unreliable and confusing for users. Users were confounded when Cmd+V on Mac
didn't work for paste connecting to Windows, or when pasting via Ctrl+V did
nothing when a remotely-running terminal emulator actually required
Ctrl+Shift+V for paste, or when attempting to paste through clicking with
the mouse did nothing.

4. On Copy event We are getting the data from the remote Clipboard and same
> we can send it the Local Clipboard using the Copy event to make both the
> local and remote clipboard synced.
>

Similar to paste, this does not work well in practice. Besides the issues
with keyboard events described above, there are timing issues with
retrieval of clipboard data. There is no guarantee that the remote
clipboard data will be received locally within a reasonable time frame of
Ctrl+C being pressed. Because the clipboard can only be modified during the
"copy" event itself, something must block the main JavaScript thread while
clipboard data is being received. We did exactly this in older releases of
Guacamole, through using synchronous XMLHttpRequest to force the thread to
block while the server awaits clipboard data, but again ran into issues:

* As with paste, the copy event will not occur during remote mouse
interaction.
* As with paste, platform and application differences in keyboard shortcuts
cannot be reliably handled or predicted.
* Synchronous XMLHttpRequest is deprecated and can no longer be relied upon.

5. Main task is to sync the Local and remote Clipboard before copying and
> pasting data.
>
> *My Queries  are as follows :- *
>
>
> 3. Can't we send plain data so that we don't have to decode or encode the
> data in Clipboard scenario as it can increase the performance ?
>
>
>
No. There is no such thing as "plain data". For communication between two
systems to make sense (between Guacamole client and server), there must be
an agreed upon encoding for data sent and received. Guacamole uses UTF-8
for transmitted text, and the processing required to transform JavaScript's
own Unicode strings into UTF-8 is very minimal.

4. Can't we make a ajax request to get the plain data which is sent by
> remote server { on copy event }. We can save the data in guacamole server
> when we receive data from remote server and on copy event fire an ajax
> request ).
>

No (see above-described issues with copy). Being able to modify local
clipboard data within the copy event would require blocking the main
thread, which cannot be done reliably.


> I had already done few change in the JavaScript code to make it work. It
> is *working in Chrome* only. Microsoft Edge hangs and IE ( issues while
> updating the local clipboard ).
>

I do not recommend making these changes. It is not possible to do what you
describe reliably.

If anyone has any suggestions, Please share in this thread.
>

>From my perspective, the best path forward is to use the clipboard APIs
which are on the track for standardization and have already been adopted by
the mainstream browsers:

Seamless Clipboard Redirection from Local to Remote Desktop

[Amarjeet Singh]

Hi Team,


This is an important feature as users do  forget Ctrl+Shift+Alt  together
to open the Menu and paste the data on the clipboard menu and then paste
again on the Remote desktop.

*My Suggestions are as follows :- *

1. After more debugging I have noticed that these functions take lot of
time to process if buffer size if large ( copying or pasting large amount
of data ).


   1.
*__encode_utf8 *
   2.
*__append_utf8 *
   3.
*array_writer.sendData(__encode_utf8(text)); *
   4. *__decode_utf8*

2. There are many function in Guacamole Javascript which are independent of
user interface elements, such as the DOM and common JS functions like
getElementById where we can use Webworker to improve the performance of
Guacamole.

3. On Paste event we can get the data from the Local Clipboard and send it
to the Remote Server so that Remote server also synced with the Local
Server == And then send the Ctrl + V keys to paste the CLipboard data.

4. On Copy event We are getting the data from the remote Clipboard and same
we can send it the Local Clipboard using the Copy event to make both the
local and remote clipboard synced.

5. Main task is to sync the Local and remote Clipboard before copying and
pasting data.

*My Queries  are as follows :- *


3. Can't we send plain data so that we don't have to decode or encode the
data in Clipboard scenario as it can increase the performance ?


4. Can't we make a ajax request to get the plain data which is sent by
remote server { on copy event }. We can save the data in guacamole server
when we receive data from remote server and on copy event fire an ajax
request ).


I had already done few change in the JavaScript code to make it work.
It is *working
in Chrome* only. Microsoft Edge hangs and IE ( issues while updating the
local clipboard ).

If anyone has any suggestions, Please share in this thread.



Thanks and Regards,

Amarjeet Singh