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rxws.py
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"""
rxws: WebSocket methods implemented for OpenWebRX
This file is part of OpenWebRX,
an open-source SDR receiver software with a web UI.
Copyright (c) 2013-2015 by Andras Retzler <randras@sdr.hu>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
import base64
import hashlib
import select
import code
class WebSocketException(Exception):
pass
def handshake(myself):
my_client_id=myself.path[4:]
my_headers=myself.headers.items()
my_header_keys=map(lambda x:x[0],my_headers)
h_key_exists=lambda x:my_header_keys.count(x)
h_value=lambda x:my_headers[my_header_keys.index(x)][1]
#print "The Lambdas(tm)"
#print h_key_exists("upgrade")
#print h_value("upgrade")
#print h_key_exists("sec-websocket-key")
if (not h_key_exists("upgrade")) or not (h_value("upgrade")=="websocket") or (not h_key_exists("sec-websocket-key")):
raise WebSocketException
ws_key=h_value("sec-websocket-key")
ws_key_toreturn=base64.b64encode(hashlib.sha1.new(ws_key+"258EAFA5-E914-47DA-95CA-C5AB0DC85B11").digest())
#A sample list of keys we get: [('origin', 'http://localhost:8073'), ('upgrade', 'websocket'), ('sec-websocket-extensions', 'x-webkit-deflate-frame'), ('sec-websocket-version', '13'), ('host', 'localhost:8073'), ('sec-websocket-key', 't9J1rgy4fc9fg2Hshhnkmg=='), ('connection', 'Upgrade'), ('pragma', 'no-cache'), ('cache-control', 'no-cache')]
myself.wfile.write("HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: "+ws_key_toreturn+"\r\nCQ-CQ-de: HA5KFU\r\n\r\n")
def get_header(size):
#this does something similar: https://github.com/lemmingzshadow/php-websocket/blob/master/server/lib/WebSocket/Connection.php
ws_first_byte=0b10000010 # FIN=1, OP=2
if(size>125):
ws_second_byte=126 # The following two bytes will indicate frame size
extended_size=chr((size>>8)&0xff)+chr(size&0xff) #Okay, it uses reverse byte order (little-endian) compared to anything else sent on TCP
else:
ws_second_byte=size
#256 bytes binary message in a single unmasked frame | 0x82 0x7E 0x0100 [256 bytes of binary data]
extended_size=""
return chr(ws_first_byte)+chr(ws_second_byte)+extended_size
def code_payload(data, masking_key=""):
# both encode or decode
if masking_key=="":
key = (61, 84, 35, 6)
else:
key = [ord(i) for i in masking_key]
encoded=""
for i in range(0,len(data)):
encoded+=chr(ord(data[i])^key[i%4])
return encoded
def xxdg(data):
output=""
for i in range(0,len(data)/8):
output+=xxd(data[i:i+8])
if i%2: output+="\n"
else: output+=" "
return output
def xxd(data):
#diagnostic purposes only
output=""
for d in data:
output+=hex(ord(d))[2:].zfill(2)+" "
return output
#for R/W the WebSocket, use recv/send
#for reading the TCP socket, use readsock
#for writing the TCP socket, use myself.wfile.write and flush
def readsock(myself,size,blocking):
#http://thenestofheliopolis.blogspot.hu/2011/01/how-to-implement-non-blocking-two-way.html
if blocking:
return myself.rfile.read(size)
else:
poll = select.poll()
poll.register(myself.rfile.fileno(), select.POLLIN or select.POLLPRI)
fd = poll.poll(0) #timeout is 0
if len(fd):
f = fd[0]
if f[1] > 0:
return myself.rfile.read(size)
return ""
def recv(myself, blocking=False, debug=False):
bufsize=70000
#myself.connection.setblocking(blocking) #umm... we cannot do that with rfile
if debug:
print("ws_recv begin")
try:
data=readsock(myself,6,blocking)
#print "rxws.recv bytes:",xxd(data)
except:
if debug: print("ws_recv error")
return ""
if debug: print("ws_recv recved")
if(len(data)==0): return ""
fin=ord(data[0])&128!=0
is_text_frame=ord(data[0])&15==1
length=ord(data[1])&0x7f
data+=readsock(myself,length,blocking)
#print "rxws.recv length is ",length," (multiple packets together?) len(data) =",len(data)
has_one_byte_length=length<125
masked=ord(data[1])&0x80!=0
#print "len=", length, len(data)-2
#print "fin, is_text_frame, has_one_byte_length, masked = ", (fin, is_text_frame, has_one_byte_length, masked)
#print xxd(data)
if fin and is_text_frame and has_one_byte_length:
if masked:
return code_payload(data[6:], data[2:6])
else:
return data[2:]
#Useful links for ideas on WebSockets:
# http://stackoverflow.com/questions/8125507/how-can-i-send-and-receive-websocket-messages-on-the-server-side
# https://developer.mozilla.org/en-US/docs/WebSockets/Writing_WebSocket_server
# http://tools.ietf.org/html/rfc6455#section-5.2
def flush(myself):
myself.wfile.flush()
#or the socket, not the rfile:
#lR,lW,lX = select.select([],[myself.connection,],[],60)
def send(myself, data, begin_id="", debug=0):
base_frame_size=35000 #could guess by MTU?
debug=0
#try:
while True:
counter=0
from_end=len(data)-counter
if from_end+len(begin_id)>base_frame_size:
data_to_send=begin_id+data[counter:counter+base_frame_size-len(begin_id)]
header=get_header(len(data_to_send))
flush(myself)
myself.wfile.write(header+data_to_send)
flush(myself)
if debug: print("rxws.send ==================== #1 if branch :: from={0} to={1} dlen={2} hlen={3}".format(counter,counter+base_frame_size-len(begin_id),len(data_to_send),len(header)))
else:
data_to_send=begin_id+data[counter:]
header=get_header(len(data_to_send))
flush(myself)
myself.wfile.write(header+data_to_send)
flush(myself)
if debug: print("rxws.send :: #2 else branch :: dlen={0} hlen={1}".format(len(data_to_send),len(header)))
#if debug: print "header:\n"+xxdg(header)+"\n\nws data:\n"+xxdg(data_to_send)
break
counter+=base_frame_size-len(begin_id)
#except:
# pass