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.
Moved websocket.py code into a class WebSocketServer. WebSockets
server implementations will sub-class and define a handler() method
which is passed the client socket after. Global variable settings have been
changed to be parameters for WebSocketServer when created.
Subclass implementations still have to handle queueing and sending but
the parent class handles everything else (daemonizing, websocket
handshake, encode/decode, etc). It would be better if the parent class
could handle queueing and sending. This adds some buffering and
polling complexity to the parent class but it would be better to do so
at some point. However, the result is still much cleaner as can be
seen in wsecho.py.
Refactored wsproxy.py and wstest.py (formerly ws.py) to use the new
class. Added wsecho.py as a simple echo server.
- rename tests/ws.py to utils/wstest.py and add a symlink from
tests/wstest.py
- rename tests/ws.html to tests/wstest.html to match utils/wstest.py.
- add utils/wsecho.py
- add tests/wsecho.html which communicates with wsecho.py and simply
sends periodic messages and shows what is received.
- 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.
Warn early about no SSL cert and add clearer warning when a connection
comes in as SSL but no cert file exists.
For the C version, cleanup closing of the connection socket. Use
shutdown for a cleaner cleanup with the client.
- include/rfb.js: Keep track of the number of rects of each encoding
type and print them out when we close a connection (if 'info'
logging level).
- tests/vnc_perf.html: first pass at a noVNC based performance
benchmark.
- utils/wsproxy.py: Fix the output of the record filename.
- include/canvas.js: When 'debug' logging, show browser detection
values.
- test/canvas.html: Only restore the canvas to it's starting state if
the logging level is not 'debug'.
- wsproxy.py: Append the session number to the record filename so that
multiple sessions don't stomp on each other.
Add -m, --multiprocess option which forks a handler for each
connection allowing multiple connections to the same target using the
same proxy instance.
Cleaned up the output of the handler process. Each process' output is
prefixed with an ordinal value.
Changed both the C and python versions of the proxy.
Turns out when Windows is running in QEMU and a window scroll happens,
there are lots of little hextile rects sent. This is slow in noVNC.
- Some recording/playback improvement.
- Add test harness to drive playback of recordings.
- By pulling off the rect header in one chunk we get a 3X speedup in
Chrome and a 20% speedup in firefox (specifically for the scroll
test).
- Also, get rid of some noise from creating timers for handle_message.
Check to make sure there isn't already a pending timer first.
The listen port should be opened before daemonizing otherwise if
opening the port fails, the user will get no feedback. The only
complication was that the listen socket needs to not be closed as part
of daemonizing.
Thanks to http://github.com/rickr for finding it.
Joel Martin