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.
The following API changes may affect integrators:
- Settings have been moved out of the RFB.connect() call. Each
setting now has it's own setter function: setEncrypt, setBase64,
setTrueColor, setCursor.
- Encrypt and cursor settings now default to on.
- CSS changes:
- VNC_status_bar for input buttons switched to a element class.
- VNC_buttons split into VNC_buttons_right and
VNC_buttons_left
- New id styles for VNC_settings_menu and VNC_setting
Note: the encrypt, true_color and cursor, logging setting can all be
set on load using query string variables (in addition to host, port
and password).
Client cursor (cursor pseudo-encoding) support has been polished and
activated.
The RFB settings are now presented as radio button list items in
a drop-down "Settings" menu when using the default controls.
Also, in the settings menu is the ability to select between alternate
style-sheets.
Cookie and stylesheet selection support added to util.js.
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).
Add message/state pollling in web-socket-js. Since Opera tends to drop
message events, we can dramatically increase performance by polling
every now for message event data.
Also, add more direct calls to update readyState so that it's not
missed when Opera drops events.
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.
Pull in LGPL md5.c and md5.h files (written by Ulrich Drepper).
Now both python and C version of the proxy support both protocol 75
and protocol 76 (hybi 00).
Reorganize websocket.py slightly to match websocket.c.
Interesting. Enough has changed in the Canvas tile operations, that
Canvas.prefer_js=true is better for firefox/gecko too. Approximately
2X improvement in firefox for large hextile renders.
Looks like disabling web-socket-js debug messages by default that we
get a minor speedup.
Python proxy should support both 75 and 76 (00) modes. Also, update ws
test to more reliably hit the WebSockets ordering/drop issue.
The purpose of the code is to be incorporated into other web projects
(whether those are free or not). AGPL prevents combination with other
HTML and javascript that is under a weaker (or proprietary) license.
Better would be a lesser AGPL, but there is not GNU standard for that.
So LGPL-3 meets most of my requirements. If somebody modifies the
actual client code and conveys it, then they must release the changes
under LGPL-3 also.
Add some implementation notes in docs/notes.
Joel Martin