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.
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.
- pass CFLAGS and LDFLAGS in case one needs to use -m32
- link to libcrypto for _ERR_print_errors_fp
- __THROW is non-standard define it to nothing by default
- use b64_ntop and b64_pton instead of mangled versions, OSX doesn't mangle them in the same way
- access() takes two arguments!
Signed-off-by: François Revol <revol@free.fr>
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.
I've decided that debug/develop/extra features will just be in the
python version of the proxy. The C version (and other versions) will
just have the core functionality (unless someone wants to support it).
Interestingly, the bug depends on compiler behavior. If local
variables are automatically initialized to 0, then this always caused
the program to error out indicating a failure to parse the listen
port. Otherwise, the test was a no-op (except the rare case where the
memory happened to be zero anyways).
Thanks to Eugen Melnikoff for finding this.
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
François Revol