tools/usb_gadget/server.py

# Copyright 2014 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.

"""WSGI application to manage a USB gadget.
"""

import datetime
import hashlib
import re
import subprocess
import sys
import time
import urllib2

from tornado import httpserver
from tornado import ioloop
from tornado import web

import default_gadget

VERSION_PATTERN = re.compile(r'.*usb_gadget-([a-z0-9]{32})\.zip')

address = None
chip = None
claimed_by = None
default = default_gadget.DefaultGadget()
gadget = None
hardware = None
interface = None
port = None


def SwitchGadget(new_gadget):
  if chip.IsConfigured():
    chip.Destroy()

  global gadget
  gadget = new_gadget
  gadget.AddStringDescriptor(3, address)
  chip.Create(gadget)


class VersionHandler(web.RequestHandler):

  def get(self):
    version = 'unpackaged'
    for path in sys.path:
      match = VERSION_PATTERN.match(path)
      if match:
        version = match.group(1)
        break

    self.write(version)


class UpdateHandler(web.RequestHandler):

  def post(self):
    fileinfo = self.request.files['file'][0]

    match = VERSION_PATTERN.match(fileinfo['filename'])
    if match is None:
      self.write('Filename must contain MD5 hash.')
      self.set_status(400)
      return

    content = fileinfo['body']
    md5sum = hashlib.md5(content).hexdigest()
    if md5sum != match.group(1):
      self.write('File hash does not match.')
      self.set_status(400)
      return

    filename = 'usb_gadget-{}.zip'.format(md5sum)
    with open(filename, 'wb') as f:
      f.write(content)

    args = ['/usr/bin/python', filename,
            '--interface', interface,
            '--port', str(port),
            '--hardware', hardware]
    if claimed_by is not None:
      args.extend(['--start-claimed', claimed_by])

    print 'Reloading with version {}...'.format(md5sum)

    global http_server
    if chip.IsConfigured():
      chip.Destroy()
    http_server.stop()

    child = subprocess.Popen(args, close_fds=True)

    while True:
      child.poll()
      if child.returncode is not None:
        self.write('New package exited with error {}.'
                   .format(child.returncode))
        self.set_status(500)

        http_server = httpserver.HTTPServer(app)
        http_server.listen(port)
        SwitchGadget(gadget)
        return

      try:
        f = urllib2.urlopen('http://{}/version'.format(address))
        if f.getcode() == 200:
          # Update complete, wait 1 second to make sure buffers are flushed.
          io_loop = ioloop.IOLoop.instance()
          io_loop.add_timeout(datetime.timedelta(seconds=1), io_loop.stop)
          return
      except urllib2.URLError:
        pass
      time.sleep(0.1)


class ClaimHandler(web.RequestHandler):

  def post(self):
    global claimed_by

    if claimed_by is None:
      claimed_by = self.get_argument('session_id')
    else:
      self.write('Device is already claimed by "{}".'.format(claimed_by))
      self.set_status(403)


class UnclaimHandler(web.RequestHandler):

  def post(self):
    global claimed_by
    claimed_by = None
    if gadget != default:
      SwitchGadget(default)


class UnconfigureHandler(web.RequestHandler):

  def post(self):
    SwitchGadget(default)


class DisconnectHandler(web.RequestHandler):

  def post(self):
    if chip.IsConfigured():
      chip.Destroy()


class ReconnectHandler(web.RequestHandler):

  def post(self):
    if not chip.IsConfigured():
      chip.Create(gadget)


app = web.Application([
    (r'/version', VersionHandler),
    (r'/update', UpdateHandler),
    (r'/claim', ClaimHandler),
    (r'/unclaim', UnclaimHandler),
    (r'/unconfigure', UnconfigureHandler),
    (r'/disconnect', DisconnectHandler),
    (r'/reconnect', ReconnectHandler),
])

http_server = httpserver.HTTPServer(app)