Python server for Wialon Retranslator 1.0

parser.py

# -*- coding: utf-8 -*-

import binascii
import struct


def parse(fmt, binary, offset=0):
    '''
    Unpack the string

    fmt      @see https://docs.python.org/2/library/struct.html#format-strings
    value    value to be formated
    offset   offset in bytes from begining
    '''
    parsed = struct.unpack_from(fmt, binary, offset)
    return parsed[0] if len(parsed) == 1 else parsed


def parsePacket(packet):
    '''
    Parse Wialon Retranslator v1.0 packet w/o first 4 bytes (packet size)
    '''

    # parsed message
    msg = {
        'id': 0,
        'time': 0,
        'flags': 0,
        'params': {},
        'blocks': []
    }

    # parse packet info
    controller_id_size = packet.find('\x00')
    (msg['id'], msg['time'], msg['flags']) = parse('> %ds x i i' % (controller_id_size), packet)

    # get data block
    data_blocks = packet[controller_id_size + 1 + 4 + 4:]

    while len(data_blocks):
        # name offset in data block
        offset = 2 + 4 + 1 + 1
        name_size = data_blocks.find('\x00', offset) - offset
        (block_type, block_length, visible, data_type, name) = parse('> h i b b %ds' % (name_size), data_blocks)

        # constuct block info
        block = {
            'type': block_type,
            'length': block_length,
            'visibility': visible,
            'data_type': data_type,
            'name': name
        }

        # get block data
        block['data_block'] = data_blocks[offset + name_size + 1:block_length * 1 + 6]

        v = ''
        if data_type == 1:
            # text
            # TODO
            pass
        if data_type == 2:
            # binary
            if name == 'posinfo':
                v = {'lat': 0, 'lon': 0, 'h': 0, 's': 0, 'c': 0, 'sc': 0}
                (v['lon'], v['lat'], v['h']) = parse('d d d', block['data_block'])
                (v['s'], v['c'], v['sc']) = parse('> h h b', block['data_block'], 24)
        elif data_type == 3:
            # integer
            v = parse('> i', block['data_block'])
        elif data_type == 4:
            # float
            v = parse('d', block['data_block'])
        elif data_type == 5:
            # long
            v = parse('> q', block['data_block'])

        # add param to message
        msg['params'][name] = v

        # data blocks parse information
        msg['blocks'].append(block)

        # delete parsed info
        data_blocks = data_blocks[block_length + 6:]

    return msg

if __name__ == '__main__':
    # test data
    data = [
        '333533393736303133343435343835004B0BFB70000000030BBB000000270102706F73696E666F00A027AFDF5D9848403AC7253383DD4B400000000000805A40003601460B0BBB0000001200047077725F657874002B8716D9CE973B400BBB00000011010361766C5F696E707574730000000001',
        '73686d6900552d3f49000000070bbb000000270102706f73696e666f001f090e42538d3b40af8c20a82dfc4a400000000000000000006c0109ff0bbb0000000f000461646331000000000000ca21400bbb00000011010361766c5f696e7075747300000000240bbb00000012010361766c5f6f7574707574730000000037'
    ]
    for i in range(len(data)):
        print '\nParse packet: %s\n' % data[i]
        print parsePacket(binascii.unhexlify(data[i]))

server.py

# -*- coding: utf-8 -*-

import binascii
import socket

from parser import parse, parsePacket

CONNECTION = (socket.gethostname(), 12374)

server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# prevent 'ERROR: Address already in use'
server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)


server.bind((socket.gethostname(), 12374))
server.listen(1)

print "Listen {0} on {1}".format(*CONNECTION)
# Accept connections
sck, addr = server.accept()
print "Connected {0}:{1}".format(*addr)

# packet queue
queue = ''

while 1:
    data = sck.recv(1024)
    if not data:
        break
    # append to queue
    queue = queue + data

    # get first packet size
    packet_size = parse('<i', queue)
    if packet_size + 4 <= len(queue):
        # get packet
        packet = queue[4:packet_size + 4]

        # print binascii.hexlify(packet)
        print parsePacket(packet)

        # remove packet from queue
        queue = queue[packet_size + 4:]

        # packet was received successfully
        sck.send(str(0x11))

@DiegoArrietar
This sample uses Wialon Retranslator v1.0, this protocol is one of the best for data retransmission from Wialon to other server
You can find information about packets in docs http://extapi.wialon.com/hw/cfg/WialonRetranslator%201.0_en.pdf

Example from doc http://extapi.wialon.com/hw/cfg/WialonRetranslator%201.0_en.pdf:
74000000333533393736303133343435343835004B0BFB70000000030BBB000000270102706F73696E6
66F00A027AFDF5D9848403AC7253383DD4B400000000000805A40003601460B0BBB000000120004707
7725F657874002B8716D9CE973B400BBB00000011010361766C5F696E707574730000000001

But the null byte starts with 2 and parser not work

Profit :)
-controller_id_size = packet.find('\x00')
+controller_id_size = packet.find('\x00', 8)

Hi, I already started the server.py but I only have the message listen on 12374 port. But the screen have not shown anything else. Do I have to do something else or print something to look the packages. thanks.

The code works well. I had to open the port of centos. You could get the open ports in your linux with netstat -tulpn so you could look the ports. And you need to search in the firewall with the command. iptables -S. You need to have a rule to listen from that port.

Thanks for your code.

Hi Aleksey, thank you for this parsePacket function, I have found it very useful!

I noticed on some test data from a wialon local retranslator, that the latitude appeared to be in the 'lon' value and the longitude in the 'lat' value.

If I parse the following sample data using this function:
'333533393736303133343435343835004B0BFB70000000030BBB000000270102706F73696E666F00A027AFDF5D9848403AC7253383DD4B400000000000805A40003601460B0BBB0000001200047077725F657874002B8716D9CE973B400BBB00000011010361766C5F696E707574730000000001'
it yields: 'posinfo': {'c': 326, 'h': 106.0, 'lon': 55.7305664, 'sc': 11, 's': 54, 'lat': 49.1903648} which locates to here: https://www.google.com/maps/search/+49.1903648+55.7305664
Is this correct? Or is it supposed to be here:
https://www.google.com/maps/search/+55.7305664+49.1903648

I modified lines 66-67 to the following, which appears to resolve for me:
v = {'lon': 0, 'lat': 0, 'h': 0, 's': 0, 'c': 0, 'sc': 0}
(v['lon'], v['lat'], v['h']) = parse('d d d', block['data_block'])

Could this be a mistake or could there be some other reason for this being jumbled up in my environment?

Hey @bshaw-au
WOW! What a bug) So many years it was in this code!

In spec 'posinfo' binary block has structure (lon-lat)

(bytes)    Type                 Field description
8          Fractional value     Lon - longitude
8          Fractional value     Lat - latitude

So you're right, line 67 must be like this

-(v['lat'], v['lon'], v['h']) = parse('d d d', block['data_block'])
+(v['lon'], v['lat'], v['h']) = parse('d d d', block['data_block'])

I already updated code
Thanks for reporting!