Initial check-in of Linux virtual Me2Me.

remoting/tools/remoting.py

+#!/usr/bin/env python
+# Copyright (c) 2011 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+

[Wez, 2011/11/11 01:32:32]

Add a description of what this script is for.

[Wez, 2011/11/11 01:32:32]

I think the script name should describe what it does, e.g me2me_virtual_host.py

[Lambros, 2011/11/17 01:07:05]

Done.

[Lambros, 2011/11/17 01:07:05]

Done.

+import atexit
+import getpass
+import json
+import logging
+import os
+import random
+import signal
+import socket
+import subprocess
+import sys
+import time
+import urllib2
+
+# Local modules
+import gaia_auth
+import keygen
+
+REMOTING_COMMAND = ["../../out/Debug/remoting_me2me_host"]

[Sergey Ulanov, 2011/11/11 05:33:02]

Can we detect this path similar to how keygen module detects path for
chromoting_host_keygen? Currently this script works only when the current
directory is set to src/remoting/tools .

[Lambros, 2011/11/17 01:07:05]

Done.

+
+CONFIG_DIR = os.path.expanduser("~/.config/chrome-remote-desktop")
+
+X_LOCK_FILE_TEMPLATE = "/tmp/.X%d-lock"
+FIRST_X_DISPLAY_NUMBER = 20
+
+X_AUTH_FILE = os.path.expanduser("~/.Xauthority")
+os.environ["XAUTHORITY"] = X_AUTH_FILE
+
+g_desktops = []
+
+class Authentication:
+  """Manage authentication tokens for Chromoting/xmpp"""
+  def __init__(self, config_file):
+    self.config_file = config_file
+
+  def refresh_tokens(self):
+    print "Email:",
+    self.login = raw_input()
+    password = getpass.getpass("Password: ")
+
+    chromoting_auth = gaia_auth.GaiaAuthenticator('chromoting')
+    self.chromoting_auth_token = chromoting_auth.authenticate(self.login,
+                                                              password)
+
+    xmpp_authenticator = gaia_auth.GaiaAuthenticator('chromiumsync')
+    self.xmpp_auth_token = xmpp_authenticator.authenticate(self.login,
+                                                           password)
+
+  def load_config(self):

[Wez, 2011/11/11 01:32:32]

nit: Why load/write_config rather than read/write_config or load/save_config?

[Lambros, 2011/11/17 01:07:05]

Done (load/save).

+    try:
+      settings_file = open(self.config_file, 'r')
+      data = json.load(settings_file)
+      settings_file.close()
+      self.login = data["xmpp_login"]
+      self.chromoting_auth_token = data["chromoting_auth_token"]
+      self.xmpp_auth_token = data["xmpp_auth_token"]
+    except:
+      return False
+    return True
+
+  def write_config(self):
+    data = {
+        "xmpp_login": self.login,
+        "chromoting_auth_token": self.chromoting_auth_token,
+        "xmpp_auth_token": self.xmpp_auth_token,
+    }
+    os.umask(0066) # Set permission mask for created file.

[Wez, 2011/11/11 01:32:32]

Does this fail with an error return code, or an exception?  What happens then?

[Lambros, 2011/11/17 01:07:05]

umask() cannot fail, but the open/write/close calls can throw.  In that case,
the script would exit and print a Python stack trace.

+    settings_file = open(self.config_file, 'w')
+    settings_file.write(json.dumps(data, indent=2))
+    settings_file.close()
+
+
+class Host:
+  """Create a new, or manage an existing, host registration."""

[Wez, 2011/11/11 01:32:32]

Surely this object effectively _is_ a virtual Me2Me Host configuration? 
Creating one of these doesn't actually create a registration until you call
register_new(), for example.

[Lambros, 2011/11/17 01:07:05]

Reworded comment.

+
+  server = 'www.googleapis.com'
+  url = 'https://' + server + '/chromoting/v1/@me/hosts'
+
+  def __init__(self, config_file):
+    self.config_file = config_file
+
+  @staticmethod
+  def random_uuid():
+    return ("%04x%04x-%04x-%04x-%04x-%04x%04x%04x" %
+            tuple(map(lambda x: random.randrange(0, 0x10000), range(8))))

[Wez, 2011/11/11 01:32:32]

Replace this with uuid.uuid1()?

[Lambros, 2011/11/17 01:07:05]

Done.

+
+  def register_new(self, auth):

[Wez, 2011/11/11 01:32:32]

Split this method down into generate_config(), register(), etc?

[Wez, 2011/11/11 01:32:32]

Rename this method create_host() or create_config(), and add a short description
of how the caller uses it?

[Lambros, 2011/11/17 01:07:05]

Done.

+    self.host_id = self.random_uuid()
+    logging.info("HostId: " + self.host_id)
+    self.host_name = socket.gethostname()
+    logging.info("HostName: " + self.host_name)
+
+    logging.info("Generating RSA key pair...")
+    (self.private_key, public_key) = keygen.generateRSAKeyPair()
+    logging.info("Done")
+
+    json_data = {
+        "data": {
+            "hostId": self.host_id,
+            "hostName": self.host_name,
+            "publicKey": public_key,
+        }
+    }
+    params = json.dumps(json_data)
+    headers = {
+        "Authorization": "GoogleLogin auth=" + auth.chromoting_auth_token,
+        "Content-Type": "application/json",
+    }
+
+    request = urllib2.Request(self.url, params, headers)
+    opener = urllib2.OpenerDirector()
+    opener.add_handler(urllib2.HTTPDefaultErrorHandler())
+
+    logging.info("Registering host with directory service...")
+    try:
+      res = urllib2.urlopen(request)
+      data = res.read()
+    except urllib2.HTTPError, err:
+      logging.error("Directory returned error: " + str(err))
+      logging.error(err.read())
+      sys.exit(1)
+    logging.info("Done")
+
+  def load_config(self):

[Wez, 2011/11/11 01:32:32]

load vs read / save vs write

[Lambros, 2011/11/17 01:07:05]

Done.

+    try:
+      settings_file = open(self.config_file, 'r')
+      data = json.load(settings_file)
+      settings_file.close()
+      self.host_id = data["host_id"]
+      self.host_name = data["host_name"]
+      self.private_key = data["private_key"]
+    except:
+      return False
+    return True
+
+  def write_config(self):
+    data = {
+        "host_id": self.host_id,
+        "host_name": self.host_name,
+        "private_key": self.private_key,
+    }
+    os.umask(0066) # Set permission mask for created file.
+    settings_file = open(self.config_file, 'w')
+    settings_file.write(json.dumps(data, indent=2))
+    settings_file.close()
+
+
+def cleanup():
+  logging.info("Cleanup.")
+
+  for desktop in g_desktops:
+    if desktop.x_proc:
+      logging.info("Terminating Xvfb")
+      desktop.x_proc.terminate()
+
+def signal_handler(signum, stackframe):
+    # Exit cleanly so the atexit handler, cleanup(), gets called.
+    raise SystemExit
+
+
+class Desktop:
+  """Manage a single virtual desktop"""
+  def __init__(self):
+    self.x_proc = None
+    g_desktops.append(self)
+
+  @staticmethod
+  def get_unused_display_number():
+    """Return a candidate display number for which there is currently no
+    X Server lock file"""
+    display = FIRST_X_DISPLAY_NUMBER
+    while os.path.exists(X_LOCK_FILE_TEMPLATE % display):
+      display += 1
+    return display
+
+  def launch_x_server(self):
+    display = self.get_unused_display_number()
+    ret_code = subprocess.call("xauth add :%d . `mcookie`" % display,
+                               shell=True)
+    if ret_code != 0:
+      logging.error("xauth failed with code %d" % ret_code)
+      return 1
+    logging.info("Starting Xvfb on display :%d" % display);
+    self.x_proc = subprocess.Popen(["Xvfb", ":%d" % display,
+                                    "-auth", X_AUTH_FILE,
+                                    "-nolisten", "tcp",
+                                    "-screen", "0", "1024x768x24",
+                                    ])
+    if not self.x_proc.pid:
+      logging.info("Could not start Xvfb.")
+      return 1
+
+    # Create clean environment for new session, so it is cleanly separated from
+    # the user's console X session.
+    self.child_env = {"DISPLAY": ":%d" % display}
+    for key in ["HOME", "PATH"]:
+      self.child_env[key] = os.environ[key]

[Wez, 2011/11/11 01:32:32]

Are these really all we need for a valid environment?  Will session startup
source their .profile for us?

[Lambros, 2011/11/17 01:07:05]

This is essentially what GNOME Display Manager does, except with a few more
variables.  I've added these here.

+
+    # Wait for X to be active.
+    for test in range(5):
+      proc = subprocess.Popen("xdpyinfo > /dev/null", env=self.child_env,
+                              shell=True)
+      pid, retcode = os.waitpid(proc.pid, 0)
+      if retcode == 0:
+        break
+      time.sleep(0.5)
+    if retcode != 0:
+      logging.info("Could not connect to Xvfb.")
+      return 1
+    else:
+      logging.info("Xvfb is active.")
+
+  def launch_x_session(self):
+    # Start desktop session
+    session_proc = subprocess.Popen("/etc/X11/Xsession",
+                                    cwd=os.environ["HOME"],
+                                    env=self.child_env)
+    if not session_proc.pid:
+      logging.info("Could not start X session")
+      return 1
+
+  def launch_host(self):
+    # Start remoting host
+    self.host_proc = subprocess.Popen(REMOTING_COMMAND, env=self.child_env)
+    if not self.host_proc.pid:
+      logging.info("Could not start remoting host")
+      return 1
+
+
+def main():
+  atexit.register(cleanup)

[Wez, 2011/11/11 01:32:32]

This means at present that killing the script will kill the desktop(s).  We
previously discussed having this script effectively "manage" the desktops, so
the terminal you run it on doesn't need to linger - is that planned for a future
CL?

[Lambros, 2011/11/17 01:07:05]

Future CL - a bit complex to include in here.  Note that self-daemonizing is not
necessarily a good thing - read http://mywiki.wooledge.org/ProcessManagement
and search that page for "self-daemonizing".
:)

[Wez, 2011/11/17 02:19:28]

That page is really talking about how self-daemonizing makes it hard for a
system-wide, long-lived daemon-management process to manage daemons, which is a
valid point but doesn't apply to a daemon the user runs themself, for which
there is no "manager" process.

Of course if you went on to make this script run as a daemon on Linux, and spawn
the user's desktop for them as soon as the machine starts up, I'm sure folks
wouldn't complain!

+
+  for s in (
+      signal.SIGINT,
+      signal.SIGTERM,
+  ):

[Wez, 2011/11/11 01:32:32]

Could this be a single line?  It looks strange laid out like this.

[Lambros, 2011/11/17 01:07:05]

Done.  I think that list is exhaustive.  Trapping things like SIGSEGV, SIGILL
etc in a Python-interpreted script is silly! :)

+    signal.signal(s, signal_handler)
+
+  # Ensure full path to config directory exists.
+  if not os.path.exists(CONFIG_DIR):
+    os.makedirs(CONFIG_DIR, mode=0700)
+
+  auth = Authentication(os.path.join(CONFIG_DIR, "auth.json"))
+  if not auth.load_config():
+    auth.refresh_tokens()
+    auth.write_config()
+
+  host = Host(os.path.join(CONFIG_DIR, "host.json"))
+
+  if not host.load_config():
+    host.register_new(auth)
+    host.write_config()

[Wez, 2011/11/11 01:32:32]

Support for multiple Host configurations, and re-starting failed Desktops, is
for a follow-up CL?

[Lambros, 2011/11/17 01:07:05]

I think so.

+
+  logging.info("Using host_id: " + host.host_id)
+
+  desktop = Desktop()
+  desktop.launch_x_server()
+  desktop.launch_x_session()
+  desktop.launch_host()

[Wez, 2011/11/11 01:32:32]

If one of these fails, it looks like you'll get error return codes, which you'll
ignore?

[Lambros, 2011/11/17 01:07:05]

Turned these into Exceptions, which will kill the script and show a stack trace.
 I've also added a bit of error-handling in the case of authentication failure
when entering email/password.

+
+  while True:
+    pid, status = os.wait()
+    logging.info("wait() returned (%s,%s)" % (pid, status))
+
+    if pid == desktop.x_proc.pid:
+      logging.info("X server process terminated with code %d", status)
+      break
+
+    if pid == desktop.host_proc.pid:
+      logging.info("Host process terminated, relaunching")
+      desktop.launch_host()
+
+if __name__ == "__main__":
+  logging.basicConfig(level=logging.DEBUG)
+  sys.exit(main())