blob: 053ad4ab5ac8b74391bfce098d5952eba416dd88 [file] [log] [blame]
# Copyright 2011 Google Inc. All Rights Reserved.
"""WebRTC Demo
This module demonstrates the WebRTC API by implementing a simple video chat app.
import cgi
import json
import logging
import os
import random
import threading
import jinja2
import webapp2
from google.appengine.api import memcache
from google.appengine.api import urlfetch
import analytics
import analytics_page
import compute_page
import constants
jinja_environment = jinja2.Environment(
def generate_random(length):
word = ''
for _ in range(length):
word += random.choice('0123456789')
return word
# HD is on by default for desktop Chrome, but not Android or Firefox (yet)
def get_hd_default(user_agent):
if 'Android' in user_agent or not 'Chrome' in user_agent:
return 'false'
return 'true'
# iceServers will be filled in by the TURN HTTP request.
def make_pc_config(ice_transports):
config = {
'iceServers': [],
'bundlePolicy': 'max-bundle',
'rtcpMuxPolicy': 'require'
if ice_transports:
config['iceTransports'] = ice_transports
return config
def add_media_track_constraint(track_constraints, constraint_string):
tokens = constraint_string.split(':')
mandatory = True
if len(tokens) == 2:
# If specified, e.g. mandatory:minHeight=720, set mandatory appropriately.
mandatory = (tokens[0] == 'mandatory')
# Otherwise, default to mandatory, except for goog constraints, which
# won't work in other browsers.
mandatory = not tokens[0].startswith('goog')
tokens = tokens[-1].split('=')
if len(tokens) == 2:
if mandatory:
track_constraints['mandatory'][tokens[0]] = tokens[1]
track_constraints['optional'].append({tokens[0]: tokens[1]})
logging.error('Ignoring malformed constraint: ' + constraint_string)
def make_media_track_constraints(constraints_string):
if not constraints_string or constraints_string.lower() == 'true':
track_constraints = True
elif constraints_string.lower() == 'false':
track_constraints = False
track_constraints = {'mandatory': {}, 'optional': []}
for constraint_string in constraints_string.split(','):
add_media_track_constraint(track_constraints, constraint_string)
return track_constraints
def make_media_stream_constraints(audio, video, firefox_fake_device):
stream_constraints = (
{'audio': make_media_track_constraints(audio),
'video': make_media_track_constraints(video)})
if firefox_fake_device:
stream_constraints['fake'] = True'Applying media constraints: ' + str(stream_constraints))
return stream_constraints
def maybe_add_constraint(constraints, param, constraint):
if (param.lower() == 'true'):
constraints['optional'].append({constraint: True})
elif (param.lower() == 'false'):
constraints['optional'].append({constraint: False})
return constraints
def make_pc_constraints(dtls, dscp, ipv6):
constraints = {'optional': []};
maybe_add_constraint(constraints, dtls, 'DtlsSrtpKeyAgreement')
maybe_add_constraint(constraints, dscp, 'googDscp')
maybe_add_constraint(constraints, ipv6, 'googIPv6')
return constraints
def append_url_arguments(request, link):
arguments = request.arguments()
if len(arguments) == 0:
return link
link += ('?' + cgi.escape(arguments[0], True) + '=' +
cgi.escape(request.get(arguments[0]), True))
for argument in arguments[1:]:
link += ('&' + cgi.escape(argument, True) + '=' +
cgi.escape(request.get(argument), True))
return link
def get_wss_parameters(request):
wss_host_port_pair = request.get('wshpp')
wss_tls = request.get('wstls')
if not wss_host_port_pair:
# Attempt to get a wss server from the status provided by prober,
# if that fails, use fallback value.
memcache_client = memcache.Client()
wss_active_host = memcache_client.get(constants.WSS_HOST_ACTIVE_HOST_KEY)
if wss_active_host in constants.WSS_HOST_PORT_PAIRS:
wss_host_port_pair = wss_active_host
'Invalid or no value returned from memcache, using fallback: '
+ json.dumps(wss_active_host))
wss_host_port_pair = constants.WSS_HOST_PORT_PAIRS[0]
if wss_tls and wss_tls == 'false':
wss_url = 'ws://' + wss_host_port_pair + '/ws'
wss_post_url = 'http://' + wss_host_port_pair
wss_url = 'wss://' + wss_host_port_pair + '/ws'
wss_post_url = 'https://' + wss_host_port_pair
return (wss_url, wss_post_url)
def get_version_info():
path = os.path.join(os.path.dirname(__file__), 'version_info.json')
f = open(path)
if f is not None:
return json.load(f)
except ValueError as e:
logging.warning('version_info.json cannot be decoded: ' + str(e))
except IOError as e:'version_info.json cannot be opened: ' + str(e))
return None
# Returns appropriate room parameters based on query parameters in the request.
# TODO(tkchin): move query parameter parsing to JS code.
def get_room_parameters(request, room_id, client_id, is_initiator):
error_messages = []
warning_messages = []
# Get the base url without arguments.
base_url = request.path_url
user_agent = request.headers['User-Agent']
response_type = request.get('t')
# Which ICE candidates to allow. This is useful for forcing a call to run
# over TURN, by setting it=relay.
ice_transports = request.get('it')
# Which TURN transport= to allow (i.e., only TURN URLs with transport=<tt>
# will be used). This is useful for forcing a session to use TURN/TCP, by
# setting it=relay&tt=tcp.
turn_transports = request.get('tt')
# A HTTP server that will be used to find the right TURN servers to use, as
# described in
turn_base_url = request.get('ts', default_value = constants.TURN_BASE_URL)
# Use "audio" and "video" to set the media stream constraints. Defined here:
# "true" and "false" are recognized and interpreted as bools, for example:
# "?audio=true&video=false" (Start an audio-only call.)
# "?audio=false" (Start a video-only call.)
# If unspecified, the stream constraint defaults to True.
# To specify media track constraints, pass in a comma-separated list of
# key/value pairs, separated by a "=". Examples:
# "?audio=googEchoCancellation=false,googAutoGainControl=true"
# (Disable echo cancellation and enable gain control.)
# "?video=minWidth=1280,minHeight=720,googNoiseReduction=true"
# (Set the minimum resolution to 1280x720 and enable noise reduction.)
# Keys starting with "goog" will be added to the "optional" key; all others
# will be added to the "mandatory" key.
# To override this default behavior, add a "mandatory" or "optional" prefix
# to each key, e.g.
# "?video=optional:minWidth=1280,optional:minHeight=720,
# mandatory:googNoiseReduction=true"
# (Try to do 1280x720, but be willing to live with less; enable
# noise reduction or die trying.)
# The audio keys are defined here: talk/app/webrtc/
# The video keys are defined here: talk/app/webrtc/
audio = request.get('audio')
video = request.get('video')
# Pass firefox_fake_device=1 to pass fake: true in the media constraints,
# which will make Firefox use its built-in fake device.
firefox_fake_device = request.get('firefox_fake_device')
# The hd parameter is a shorthand to determine whether to open the
# camera at 720p. If no value is provided, use a platform-specific default.
# When defaulting to HD, use optional constraints, in case the camera
# doesn't actually support HD modes.
hd = request.get('hd').lower()
if hd and video:
message = 'The "hd" parameter has overridden video=' + video
# HTML template is UTF-8, make sure the string is UTF-8 as well.
if hd == 'true':
video = 'mandatory:minWidth=1280,mandatory:minHeight=720'
elif not hd and not video and get_hd_default(user_agent) == 'true':
video = 'optional:minWidth=1280,optional:minHeight=720'
if request.get('minre') or request.get('maxre'):
message = ('The "minre" and "maxre" parameters are no longer ' +
'supported. Use "video" instead.')
# HTML template is UTF-8, make sure the string is UTF-8 as well.
# Options for controlling various networking features.
dtls = request.get('dtls')
dscp = request.get('dscp')
ipv6 = request.get('ipv6')
debug = request.get('debug')
if debug == 'loopback':
# Set dtls to false as DTLS does not work for loopback.
dtls = 'false'
include_loopback_js = '<script src="/js/loopback.js"></script>'
include_loopback_js = ''
# TODO(tkchin): We want to provide a TURN request url on the initial get,
# but we don't provide client_id until a join. For now just generate
# a random id, but we should make this better.
username = client_id if client_id is not None else generate_random(9)
if len(turn_base_url) > 0:
turn_url = constants.TURN_URL_TEMPLATE % \
(turn_base_url, username, constants.CEOD_KEY)
turn_url = ''
pc_config = make_pc_config(ice_transports)
pc_constraints = make_pc_constraints(dtls, dscp, ipv6)
offer_options = {};
media_constraints = make_media_stream_constraints(audio, video,
wss_url, wss_post_url = get_wss_parameters(request)
bypass_join_confirmation = 'BYPASS_JOIN_CONFIRMATION' in os.environ and \
os.environ['BYPASS_JOIN_CONFIRMATION'] == 'True'
params = {
'error_messages': error_messages,
'warning_messages': warning_messages,
'is_loopback' : json.dumps(debug == 'loopback'),
'pc_config': json.dumps(pc_config),
'pc_constraints': json.dumps(pc_constraints),
'offer_options': json.dumps(offer_options),
'media_constraints': json.dumps(media_constraints),
'turn_url': turn_url,
'turn_transports': turn_transports,
'include_loopback_js' : include_loopback_js,
'wss_url': wss_url,
'wss_post_url': wss_post_url,
'bypass_join_confirmation': json.dumps(bypass_join_confirmation),
'version_info': json.dumps(get_version_info())
if room_id is not None:
room_link = request.host_url + '/r/' + room_id
room_link = append_url_arguments(request, room_link)
params['room_id'] = room_id
params['room_link'] = room_link
if client_id is not None:
params['client_id'] = client_id
if is_initiator is not None:
params['is_initiator'] = json.dumps(is_initiator)
return params
# For now we have (room_id, client_id) pairs are 'unique' but client_ids are
# not. Uniqueness is not enforced however and bad things may happen if RNG
# generates non-unique numbers. We also have a special loopback client id.
# TODO(tkchin): Generate room/client IDs in a unique way while handling
# loopback scenario correctly.
class Client:
def __init__(self, is_initiator):
self.is_initiator = is_initiator
self.messages = []
def add_message(self, msg):
def clear_messages(self):
self.messages = []
def set_initiator(self, initiator):
self.is_initiator = initiator
def __str__(self):
return '{%r, %d}' % (self.is_initiator, len(self.messages))
class Room:
def __init__(self):
self.clients = {}
def add_client(self, client_id, client):
self.clients[client_id] = client
def remove_client(self, client_id):
del self.clients[client_id]
def get_occupancy(self):
return len(self.clients)
def has_client(self, client_id):
return client_id in self.clients
def get_client(self, client_id):
return self.clients[client_id]
def get_other_client(self, client_id):
for key, client in self.clients.items():
if key is not client_id:
return client
return None
def __str__(self):
return str(self.clients.keys())
def get_memcache_key_for_room(host, room_id):
return '%s/%s' % (host, room_id)
def add_client_to_room(request, room_id, client_id, is_loopback):
key = get_memcache_key_for_room(request.host_url, room_id)
memcache_client = memcache.Client()
error = None
retries = 0
room = None
# Compare and set retry loop.
while True:
is_initiator = None
messages = []
room_state = ''
room = memcache_client.gets(key)
if room is None:
# 'set' and another 'gets' are needed for CAS to work.
if not memcache_client.set(key, Room()):
logging.warning('memcache.Client.set failed for key ' + key)
error = constants.RESPONSE_ERROR
room = memcache_client.gets(key)
occupancy = room.get_occupancy()
if occupancy >= 2:
error = constants.RESPONSE_ROOM_FULL
if room.has_client(client_id):
if occupancy == 0:
is_initiator = True
room.add_client(client_id, Client(is_initiator))
if is_loopback:
room.add_client(constants.LOOPBACK_CLIENT_ID, Client(False))
is_initiator = False
other_client = room.get_other_client(client_id)
messages = other_client.messages
room.add_client(client_id, Client(is_initiator))
if memcache_client.cas(key, room, constants.ROOM_MEMCACHE_EXPIRATION_SEC):'Added client %s in room %s, retries = %d' \
%(client_id, room_id, retries))
if room.get_occupancy() == 2:
success = True
retries = retries + 1
return {'error': error, 'is_initiator': is_initiator,
'messages': messages, 'room_state': str(room)}
def remove_client_from_room(host, room_id, client_id):
key = get_memcache_key_for_room(host, room_id)
memcache_client = memcache.Client()
retries = 0
# Compare and set retry loop.
while True:
room = memcache_client.gets(key)
if room is None:
logging.warning('remove_client_from_room: Unknown room ' + room_id)
return {'error': constants.RESPONSE_UNKNOWN_ROOM, 'room_state': None}
if not room.has_client(client_id):
logging.warning('remove_client_from_room: Unknown client ' + client_id + \
' for room ' + room_id)
return {'error': constants.RESPONSE_UNKNOWN_CLIENT, 'room_state': None}
if room.has_client(constants.LOOPBACK_CLIENT_ID):
if room.get_occupancy() > 0:
room = None
if memcache_client.cas(key, room, constants.ROOM_MEMCACHE_EXPIRATION_SEC):'Removed client %s from room %s, retries=%d' \
%(client_id, room_id, retries))
return {'error': None, 'room_state': str(room)}
retries = retries + 1
def save_message_from_client(host, room_id, client_id, message):
text = None
text = message.encode(encoding='utf-8', errors='strict')
except Exception as e:
return {'error': constants.RESPONSE_ERROR, 'saved': False}
key = get_memcache_key_for_room(host, room_id)
memcache_client = memcache.Client()
retries = 0
# Compare and set retry loop.
while True:
room = memcache_client.gets(key)
if room is None:
logging.warning('Unknown room: ' + room_id)
return {'error': constants.RESPONSE_UNKNOWN_ROOM, 'saved': False}
if not room.has_client(client_id):
logging.warning('Unknown client: ' + client_id)
return {'error': constants.RESPONSE_UNKNOWN_CLIENT, 'saved': False}
if room.get_occupancy() > 1:
return {'error': None, 'saved': False}
client = room.get_client(client_id)
if memcache_client.cas(key, room, constants.ROOM_MEMCACHE_EXPIRATION_SEC):'Saved message for client %s:%s in room %s, retries=%d' \
%(client_id, str(client), room_id, retries))
return {'error': None, 'saved': True}
retries = retries + 1
class LeavePage(webapp2.RequestHandler):
def post(self, room_id, client_id):
result = remove_client_from_room(
self.request.host_url, room_id, client_id)
if result['error'] is None:'Room ' + room_id + ' has state ' + result['room_state'])
class MessagePage(webapp2.RequestHandler):
def write_response(self, result):
content = json.dumps({ 'result' : result })
def send_message_to_collider(self, room_id, client_id, message):'Forwarding message to collider for room ' + room_id +
' client ' + client_id)
wss_url, wss_post_url = get_wss_parameters(self.request)
url = wss_post_url + '/' + room_id + '/' + client_id
result = urlfetch.fetch(url=url,
if result.status_code != 200:
'Failed to send message to collider: %d' % (result.status_code))
# TODO(tkchin): better error handling.
def post(self, room_id, client_id):
message_json = self.request.body
result = save_message_from_client(
self.request.host_url, room_id, client_id, message_json)
if result['error'] is not None:
if not result['saved']:
# Other client joined, forward to collider. Do this outside the lock.
# Note: this may fail in local dev server due to not having the right
# certificate file locally for SSL validation.
# Note: loopback scenario follows this code path.
# TODO(tkchin): consider async fetch here.
self.send_message_to_collider(room_id, client_id, message_json)
class JoinPage(webapp2.RequestHandler):
def write_response(self, result, params, messages):
# TODO(tkchin): Clean up response format. For simplicity put everything in
# params for now.
params['messages'] = messages
'result': result,
'params': params
def write_room_parameters(self, room_id, client_id, messages, is_initiator):
params = get_room_parameters(self.request, room_id, client_id, is_initiator)
self.write_response('SUCCESS', params, messages)
def post(self, room_id):
client_id = generate_random(8)
is_loopback = self.request.get('debug') == 'loopback'
result = add_client_to_room(self.request, room_id, client_id, is_loopback)
if result['error'] is not None:'Error adding client to room: ' + result['error'] + \
', room_state=' + result['room_state'])
self.write_response(result['error'], {}, [])
room_id, client_id, result['messages'], result['is_initiator'])'User ' + client_id + ' joined room ' + room_id)'Room ' + room_id + ' has state ' + result['room_state'])
class MainPage(webapp2.RequestHandler):
def write_response(self, target_page, params={}):
template = jinja_environment.get_template(target_page)
content = template.render(params)
def get(self):
"""Renders index.html."""
if self.request.headers['Host'] in REDIRECT_DOMAINS:
webapp2.redirect('', permanent=True)
# Parse out parameters from request.
params = get_room_parameters(self.request, None, None, None)
# room_id/room_link will not be included in the returned parameters
# so the client will show the landing page for room selection.
self.write_response('index_template.html', params)
class RoomPage(webapp2.RequestHandler):
def write_response(self, target_page, params={}):
template = jinja_environment.get_template(target_page)
content = template.render(params)
def get(self, room_id):
"""Renders index.html or full.html."""
# Check if room is full.
room = memcache.get(
get_memcache_key_for_room(self.request.host_url, room_id))
if room is not None:'Room ' + room_id + ' has state ' + str(room))
if room.get_occupancy() >= 2:'Room ' + room_id + ' is full')
# Parse out room parameters from request.
params = get_room_parameters(self.request, room_id, None, None)
# room_id/room_link will be included in the returned parameters
# so the client will launch the requested room.
self.write_response('index_template.html', params)
class ParamsPage(webapp2.RequestHandler):
def get(self):
# Return room independent room parameters.
params = get_room_parameters(self.request, None, None, None)
app = webapp2.WSGIApplication([
('/', MainPage),
('/a/', analytics_page.AnalyticsPage),
('/compute/(\w+)/(\S+)/(\S+)', compute_page.ComputePage),
('/join/([a-zA-Z0-9-_]+)', JoinPage),
('/leave/([a-zA-Z0-9-_]+)/([a-zA-Z0-9-_]+)', LeavePage),
('/message/([a-zA-Z0-9-_]+)/([a-zA-Z0-9-_]+)', MessagePage),
('/params', ParamsPage),
('/r/([a-zA-Z0-9-_]+)', RoomPage),
], debug=True)