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#!/usr/bin/env python
############################################################################
# tools/discover.py
#
# Copyright (C) 2012 Max Holtzberg. All rights reserved.
# Author: Max Holtzberg <mh@uvc.de>
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in
# the documentation and/or other materials provided with the
# distribution.
# 3. Neither the name NuttX nor the names of its contributors may be
# used to endorse or promote products derived from this software
# without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
############################################################################
import array
import time
from socket import *
PORT = 96
DISCOVER_PROTO_ID = 0x99
DISCOVER_ALL = 0xff # 0xff means all devices
DISCOVER_REQUEST = 0x01
DISCOVER_RESPONSE = 0x02
DISCOVER_REQUEST_SIZE = 4
DISCOVER_RESPONSE_SIZE = 35
def check_sum(data):
chksum = 0
for c in data[:-1]:
chksum -= c
return (chksum & 0xff) == data[-1]
def send_discover(socket):
cmd = array.array('B', [0] * DISCOVER_REQUEST_SIZE)
cmd[0] = DISCOVER_PROTO_ID # Tag for identification of the protocol
cmd[1] = DISCOVER_REQUEST # Request command
cmd[2] = DISCOVER_ALL
chksum = 0
for c in cmd[:3]:
chksum -= c;
cmd[3] = chksum & 0xff
socket.sendto(cmd, ('<broadcast>', PORT))
def read_responses(socket):
res = []
response = array.array('B', [0] * DISCOVER_RESPONSE_SIZE)
try:
while 1:
size, src = socket.recvfrom_into(response)
if (size == DISCOVER_RESPONSE_SIZE
and response[0] == DISCOVER_PROTO_ID
and response[1] == DISCOVER_RESPONSE
and check_sum(response)):
dev = {}
dev['addr'] = src[0]
dev['descr'] = response[2:-1].tostring().rstrip('\0')
res.append(dev)
except timeout:
return res
if __name__ == '__main__':
print 'Sending discover...'
s = socket(AF_INET, SOCK_DGRAM)
s.bind(('0.0.0.0', PORT))
s.setsockopt(SOL_SOCKET, SO_BROADCAST, 1)
s.settimeout(1.0);
send_discover(s)
devices = read_responses(s)
socket.close(s)
print devices
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