blob: d2136d37524e3697783f7483749d1c4221f63217 [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 app_identity
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, ice_server_override):
config = {
'iceServers': [],
'bundlePolicy': 'max-bundle',
'rtcpMuxPolicy': 'require'
if ice_server_override:
config['iceServers'] = ice_server_override
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 ICE server 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.
ice_server_transports = request.get('tt')
# A HTTP server that will be used to find the right ICE servers to use, as
# described in
ice_server_base_url = request.get('ts', default_value =
# 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 ICE 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(ice_server_base_url) > 0:
api_key = request.get('apikey', default_value=constants.ICE_SERVER_API_KEY)
ice_server_url = constants.ICE_SERVER_URL_TEMPLATE % \
(ice_server_base_url, api_key)
ice_server_url = ''
# If defined it will override the ICE server provider and use the specified
# turn servers directly.
ice_server_override = constants.ICE_SERVER_OVERRIDE
pc_config = make_pc_config(ice_transports, ice_server_override)
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 = {
'header_message': constants.HEADER_MESSAGE,
'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),
'ice_server_url': ice_server_url,
'ice_server_transports': ice_server_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."""
# 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)
def checkIfRedirect(self):
parsed_args = ''
if self.request.headers['Host'] in constants.REDIRECT_DOMAINS:
for argument in self.request.arguments():
parameter = '=' + self.request.get(argument)
if parsed_args == '':
parsed_args += '?'
parsed_args += '&'
parsed_args += argument + parameter
redirect_url = constants.REDIRECT_URL + self.request.path + parsed_args
webapp2.redirect(redirect_url, permanent=True, abort=True)
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)