f2538f337d
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.
309 lines
11 KiB
Python
Executable File
309 lines
11 KiB
Python
Executable File
#!/usr/bin/python
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'''
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A WebSocket to TCP socket proxy with support for "wss://" encryption.
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Copyright 2010 Joel Martin
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Licensed under LGPL version 3 (see docs/LICENSE.LGPL-3)
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You can make a cert/key with openssl using:
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openssl req -new -x509 -days 365 -nodes -out self.pem -keyout self.pem
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as taken from http://docs.python.org/dev/library/ssl.html#certificates
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'''
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import socket, optparse, time, os, sys, subprocess
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from select import select
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from websocket import WebSocketServer
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class WebSocketProxy(WebSocketServer):
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"""
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Proxy traffic to and from a WebSockets client to a normal TCP
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socket server target. All traffic to/from the client is base64
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encoded/decoded to allow binary data to be sent/received to/from
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the target.
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"""
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buffer_size = 65536
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traffic_legend = """
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Traffic Legend:
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} - Client receive
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}. - Client receive partial
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{ - Target receive
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> - Target send
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>. - Target send partial
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< - Client send
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<. - Client send partial
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"""
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def __init__(self, *args, **kwargs):
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# Save off proxy specific options
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self.target_host = kwargs.pop('target_host')
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self.target_port = kwargs.pop('target_port')
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self.wrap_cmd = kwargs.pop('wrap_cmd')
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self.wrap_mode = kwargs.pop('wrap_mode')
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# Last 3 timestamps command was run
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self.wrap_times = [0, 0, 0]
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if self.wrap_cmd:
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rebinder_path = ['./', os.path.dirname(sys.argv[0])]
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self.rebinder = None
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for rdir in rebinder_path:
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rpath = os.path.join(rdir, "rebind.so")
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if os.path.exists(rpath):
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self.rebinder = rpath
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break
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if not self.rebinder:
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raise Exception("rebind.so not found, perhaps you need to run make")
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self.target_host = "127.0.0.1" # Loopback
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# Find a free high port
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sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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sock.bind(('', 0))
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self.target_port = sock.getsockname()[1]
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sock.close()
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os.environ.update({
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"LD_PRELOAD": self.rebinder,
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"REBIND_OLD_PORT": str(kwargs['listen_port']),
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"REBIND_NEW_PORT": str(self.target_port)})
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WebSocketServer.__init__(self, *args, **kwargs)
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def run_wrap_cmd(self):
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print "Starting '%s'" % " ".join(self.wrap_cmd)
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self.wrap_times.append(time.time())
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self.wrap_times.pop(0)
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self.cmd = subprocess.Popen(
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self.wrap_cmd, env=os.environ)
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self.spawn_message = True
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def started(self):
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"""
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Called after Websockets server startup (i.e. after daemonize)
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"""
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# Need to call wrapped command after daemonization so we can
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# know when the wrapped command exits
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if self.wrap_cmd:
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print " - proxying from %s:%s to '%s' (port %s)\n" % (
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self.listen_host, self.listen_port,
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" ".join(self.wrap_cmd), self.target_port)
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self.run_wrap_cmd()
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else:
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print " - proxying from %s:%s to %s:%s\n" % (
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self.listen_host, self.listen_port,
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self.target_host, self.target_port)
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def poll(self):
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# If we are wrapping a command, check it's status
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if self.wrap_cmd and self.cmd:
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ret = self.cmd.poll()
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if ret != None:
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self.vmsg("Wrapped command exited (or daemon). Returned %s" % ret)
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self.cmd = None
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if self.wrap_cmd and self.cmd == None:
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# Response to wrapped command being gone
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if self.wrap_mode == "ignore":
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pass
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elif self.wrap_mode == "exit":
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sys.exit(ret)
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elif self.wrap_mode == "respawn":
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now = time.time()
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avg = sum(self.wrap_times)/len(self.wrap_times)
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if (now - avg) < 10:
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# 3 times in the last 10 seconds
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if self.spawn_message:
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print "Command respawning too fast"
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self.spawn_message = False
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else:
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self.run_wrap_cmd()
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#
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# Routines above this point are run in the master listener
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# process.
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#
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#
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# Routines below this point are connection handler routines and
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# will be run in a separate forked process for each connection.
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#
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def new_client(self, client):
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"""
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Called after a new WebSocket connection has been established.
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"""
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self.rec = None
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if self.record:
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# Record raw frame data as a JavaScript compatible file
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fname = "%s.%s" % (self.record,
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self.handler_id)
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self.msg("opening record file: %s" % fname)
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self.rec = open(fname, 'w+')
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self.rec.write("var VNC_frame_data = [\n")
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# Connect to the target
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self.msg("connecting to: %s:%s" % (
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self.target_host, self.target_port))
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tsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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tsock.connect((self.target_host, self.target_port))
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if self.verbose and not self.daemon:
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print self.traffic_legend
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# Stat proxying
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try:
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self.do_proxy(client, tsock)
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except:
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if tsock: tsock.close()
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if self.rec:
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self.rec.write("'EOF']\n")
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self.rec.close()
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raise
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def do_proxy(self, client, target):
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"""
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Proxy client WebSocket to normal target socket.
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"""
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cqueue = []
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cpartial = ""
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tqueue = []
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rlist = [client, target]
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tstart = int(time.time()*1000)
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while True:
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wlist = []
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tdelta = int(time.time()*1000) - tstart
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if tqueue: wlist.append(target)
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if cqueue: wlist.append(client)
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ins, outs, excepts = select(rlist, wlist, [], 1)
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if excepts: raise Exception("Socket exception")
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if target in outs:
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# Send queued client data to the target
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dat = tqueue.pop(0)
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sent = target.send(dat)
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if sent == len(dat):
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self.traffic(">")
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else:
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# requeue the remaining data
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tqueue.insert(0, dat[sent:])
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self.traffic(".>")
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if client in outs:
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# Send queued target data to the client
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dat = cqueue.pop(0)
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sent = client.send(dat)
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if sent == len(dat):
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self.traffic("<")
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if self.rec:
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self.rec.write("%s,\n" %
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repr("{%s{" % tdelta + dat[1:-1]))
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else:
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cqueue.insert(0, dat[sent:])
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self.traffic("<.")
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if target in ins:
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# Receive target data, encode it and queue for client
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buf = target.recv(self.buffer_size)
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if len(buf) == 0: raise self.EClose("Target closed")
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cqueue.append(self.encode(buf))
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self.traffic("{")
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if client in ins:
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# Receive client data, decode it, and queue for target
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buf = client.recv(self.buffer_size)
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if len(buf) == 0: raise self.EClose("Client closed")
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if buf == '\xff\x00':
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raise self.EClose("Client sent orderly close frame")
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elif buf[-1] == '\xff':
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if buf.count('\xff') > 1:
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self.traffic(str(buf.count('\xff')))
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self.traffic("}")
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if self.rec:
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self.rec.write("%s,\n" %
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(repr("}%s}" % tdelta + buf[1:-1])))
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if cpartial:
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# Prepend saved partial and decode frame(s)
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tqueue.extend(self.decode(cpartial + buf))
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cpartial = ""
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else:
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# decode frame(s)
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tqueue.extend(self.decode(buf))
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else:
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# Save off partial WebSockets frame
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self.traffic(".}")
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cpartial = cpartial + buf
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if __name__ == '__main__':
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usage = "\n %prog [options]"
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usage += " [source_addr:]source_port target_addr:target_port"
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usage += "\n %prog [options]"
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usage += " [source_addr:]source_port -- WRAP_COMMAND_LINE"
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parser = optparse.OptionParser(usage=usage)
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parser.add_option("--verbose", "-v", action="store_true",
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help="verbose messages and per frame traffic")
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parser.add_option("--record",
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help="record sessions to FILE.[session_number]", metavar="FILE")
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parser.add_option("--daemon", "-D",
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dest="daemon", action="store_true",
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help="become a daemon (background process)")
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parser.add_option("--cert", default="self.pem",
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help="SSL certificate file")
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parser.add_option("--key", default=None,
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help="SSL key file (if separate from cert)")
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parser.add_option("--ssl-only", action="store_true",
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help="disallow non-encrypted connections")
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parser.add_option("--web", default=None, metavar="DIR",
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help="run webserver on same port. Serve files from DIR.")
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parser.add_option("--wrap-mode", default="exit", metavar="MODE",
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choices=["exit", "ignore", "respawn"],
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help="action to take when the wrapped program exits "
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"or daemonizes: exit (default), ignore, respawn")
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(opts, args) = parser.parse_args()
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# Sanity checks
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if len(args) < 2:
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parser.error("Too few arguments")
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if sys.argv.count('--'):
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opts.wrap_cmd = args[1:]
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else:
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opts.wrap_cmd = None
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if len(args) > 2:
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parser.error("Too many arguments")
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if opts.ssl_only and not os.path.exists(opts.cert):
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parser.error("SSL only and %s not found" % opts.cert)
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# Parse host:port and convert ports to numbers
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if args[0].count(':') > 0:
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opts.listen_host, opts.listen_port = args[0].split(':')
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else:
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opts.listen_host, opts.listen_port = '', args[0]
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try: opts.listen_port = int(opts.listen_port)
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except: parser.error("Error parsing listen port")
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if opts.wrap_cmd:
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opts.target_host = None
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opts.target_port = None
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else:
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if args[1].count(':') > 0:
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opts.target_host, opts.target_port = args[1].split(':')
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else:
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parser.error("Error parsing target")
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try: opts.target_port = int(opts.target_port)
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except: parser.error("Error parsing target port")
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# Create and start the WebSockets proxy
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server = WebSocketProxy(**opts.__dict__)
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server.start_server()
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