wswrapper:
Getting the wswrapper.c LD_PRELOAD model working has turned out to
involve too many dark corners of the glibc/POSIX file descriptor
space. I realized that 95% of what I want can be accomplished by
adding a "wrap command" mode to wsproxy.
The code is still there for now, but consider it experimental at
best. Minor fix to dup2 and add dup and dup3 logging.
wsproxy Wrap Command:
In wsproxy wrap command mode, a command line is specified instead
of a target address and port. wsproxy then uses a much simpler
LD_PRELOAD library, rebind.so, to move intercept any bind() system
calls made by the program. If the bind() call is for the wsproxy
listen port number then the real bind() system call is issued for
an alternate (free high) port on loopback/localhost. wsproxy then
forwards from the listen address/port to the moved port.
The --wrap-mode argument takes three options that determine the
behavior of wsproxy when the wrapped command returns an exit code
(exit or daemonizing): ignore, exit, respawn.
For example, this runs vncserver on turns port 5901 into
a WebSockets port (rebind.so must be built first):
./utils/wsproxy.py --wrap-mode=ignore 5901 -- vncserver :1
The vncserver command backgrounds itself so the wrap mode is set
to "ignore" so that wsproxy keeps running even after it receives
an exit code from vncserver.
wstelnet:
To demonstrate the wrap command mode, I added WebSockets telnet
client.
For example, this runs telnetd (krb5-telnetd) on turns port 2023
into a WebSockets port (using "respawn" mode since telnetd exits
after each connection closes):
sudo ./utils/wsproxy.py --wrap-mode=respawn 2023 -- telnetd -debug 2023
Then the utils/wstelnet.html page can be used to connect to the
telnetd server on port 2023. The telnet client includes VT100.js
(from http://code.google.com/p/sshconsole) which handles the
terminal emulation and rendering.
rebind:
The rebind LD_PRELOAD library is used by wsproxy in wrap command
mode to intercept bind() system calls and move the port to
a different port on loopback/localhost. The rebind.so library can
be built by running make in the utils directory.
The rebind library can be used separately from wsproxy by setting
the REBIND_OLD_PORT and REBIND_NEW_PORT environment variables
prior to executing a command. For example:
export export REBIND_PORT_OLD="23"
export export REBIND_PORT_NEW="65023"
LD_PRELOAD=./rebind.so telnetd -debug 23
Alternately, the rebind script does the same thing:
rebind 23 65023 telnetd -debug 23
Other changes/notes:
- wsproxy no longer daemonizes by default. Remove -f/--foreground
option and add -D/--deamon option.
- When wsproxy is used to wrap a command in "respawn" mode, the
command will not be respawn more often than 3 times within 10
seconds.
- Move getKeysym routine out of Canvas object so that it can be called
directly.
- Added ability to respond to normal web requests. This is basically
integrating web.py functionality into wsproxy. This is only in the
python version and it is off by default when calling wsproxy. Turn
it on with --web DIR where DIR is the web root directory.
Next task is to clean up wsproxy.py. It's gotten unwieldy and it
really no longer needs to be parallel to the C version.
- Add wsproxy README.md in utils/ directory.
- Document how to build ssl module for python 2.5 and older in wsproxy
README.
- Update browsers.md to note revision that have the webkit Canvas
rendering bug: WebKit build 66396 through 68867 (Chrome/Chromium
build 57968 through 61278).
New API:
To use the RFB object, you now must instantiate it (this allows more
than one instance of it on the same page).
rfb = new RFB(settings);
The 'settings' variable is a namespace that contains initial default
settings. These can also be set and read using 'rfb.set_FOO()' and
'rfb.get_FOO()' where FOO is the setting name. The current settings
are (and defaults) are:
- target: the DOM Canvas element to use ('VNC_canvas').
- encrypt: whether to encrypt the connection (false)
- true_color: true_color or palette (true)
- b64encode: base64 encode the WebSockets data (true)
- local_cursor: use local cursor rendering (true if supported)
- connectTimeout: milliseconds to wait for connect (2000)
- updateState: callback when RFB state changes (none)
- clipboardReceive: callback when clipboard data received (none)
The parameters to the updateState callback have also changed. The
function spec is now updateState(rfb, state, oldstate, msg):
- rfb: the RFB object that this state change is for.
- state: the new state
- oldstate: the previous state
- msg: a message associate with the state (not always set).
The clipboardReceive spec is clipboardReceive(rfb, text):
- rfb: the RFB object that this text is from.
- text: the clipboard text received.
Changes:
- The RFB and Canvas namespaces are now more proper objects. Private
implementation is no longer exposed and the public API has been made
explicit. Also, instantiation allows more than one VNC connection
on the same page (to complete this, DefaultControls will also need
this same refactoring).
- Added 'none' logging level.
- Removed automatic stylesheet selection workaround in util.js and
move it to defaultcontrols so that it doesn't interfere with
intergration.
- Also, some major JSLinting.
- Fix input, canvas, and cursor tests to work with new model.
To change the appearance of the cursor, we use the CSS cursor style
and set the url to a data URI scheme. The image data sent via the
cursor pseudo-encoding has to be encoded to a CUR format file before
being used in the data URI.
During Canvas initialization we try and set a simple cursor to see if
the browser has support. Opera is missing support for data URI scheme
in cursor URLs.
Disabled for now until we have a better way of specifying settings
overall (too many settings for control bar now).
Instead of relying on FABridge AS -> JS event delivery, we just use
the events to notify JS of pending data. The message handler then
calls the AS readSocketData routine which sends back an array of
the pending WebSocket frames.
There is still a minor bug somewhere that happens after the first
connect where the web-socket-js throws an "INVALID_STATE_ERR: Web
Socket connection has not been established". But, Opera is now usable
and we should be able to drop the packet sequence numbering and
re-ordering code.
Another minor issue to better support Opera is to move JS script
includes to the <head> of the page instead of after the body.
Fixes:
- Make sure that failed state messages stay around until next connect.
- Get status message font colors working.
- Clear RQ_reorder list on re-connect.
- Instead of onload override, move to RFB.load function that takes
a parameter for the target DOM ID. This allows the user to have
their own onload function.
- Add "VNC_" prefix to all element ID names. Only create DOM elements
if they don't already exist on the page, otherwise use the existing
elements.
- Move all styling to separate stylesheet.
- Use list model for control styling.
On the client side, this adds the as3crypto library to web-socket-js
so that the WebSocket 'wss://' scheme is supported which is WebSocket
over SSL/TLS.
Couple of downsides to the fall-back method:
- This balloons the size of the web-socket-js object from about 12K to 172K.
- Getting it working required disabling RFC2718 web proxy support
in web-socket-js.
- It makes the web-socket-js fallback even slower with the
encryption overhead.
The server side (wsproxy.py) uses python SSL support. The proxy
automatically detects the type of incoming connection whether flash
policy request, SSL/TLS handshake ('wss://') or plain socket
('ws://').
Also added a check-box to the web page to enable/disabled 'wss://'
encryption.
Joel Martin