FreeDATA/tnc/helpers.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Fri Dec 25 21:25:14 2020

@author: DJ2LS
"""

import time
import crcengine
import static


def wait(seconds):
    """

    Args:
      seconds:

    Returns:

    """
    timeout = time.time() + seconds

    while time.time() < timeout:
        time.sleep(0.01)
    return True


def get_crc_8(data):
    """Author: DJ2LS

    Get the CRC8 of a byte string

    param: data = bytes()

    Args:
      data:

    Returns:

    """
    crc_algorithm = crcengine.new("crc8-ccitt")  # load crc8 library
    crc_data = crc_algorithm(data)
    crc_data = crc_data.to_bytes(1, byteorder="big")
    return crc_data


def get_crc_16(data):
    """Author: DJ2LS

    Get the CRC16 of a byte string

    param: data = bytes()

    Args:
      data:

    Returns:

    """
    crc_algorithm = crcengine.new("crc16-ccitt-false")  # load crc16 library
    crc_data = crc_algorithm(data)
    crc_data = crc_data.to_bytes(2, byteorder="big")
    return crc_data


def get_crc_32(data):
    """Author: DJ2LS

    Get the CRC32 of a byte string

    param: data = bytes()

    Args:
      data:

    Returns:

    """
    crc_algorithm = crcengine.new("crc32")  # load crc16 library
    crc_data = crc_algorithm(data)
    crc_data = crc_data.to_bytes(4, byteorder="big")
    return crc_data


def add_to_heard_stations(dxcallsign, dxgrid, datatype, snr, offset, frequency):
    """

    Args:
      dxcallsign:
      dxgrid:
      datatype:
      snr:
      offset:
      frequency:

    Returns:

    """

    # check if buffer empty
    if len(static.HEARD_STATIONS) == 0:
        static.HEARD_STATIONS.append(
            [dxcallsign, dxgrid, int(time.time()), datatype, snr, offset, frequency]
        )
    # if not, we search and update
    else:
        for i in range(0, len(static.HEARD_STATIONS)):
            # update callsign with new timestamp
            if static.HEARD_STATIONS[i].count(dxcallsign) > 0:
                static.HEARD_STATIONS[i] = [
                    dxcallsign,
                    dxgrid,
                    int(time.time()),
                    datatype,
                    snr,
                    offset,
                    frequency,
                ]
                break
            # insert if nothing found
            if i == len(static.HEARD_STATIONS) - 1:
                static.HEARD_STATIONS.append(
                    [
                        dxcallsign,
                        dxgrid,
                        int(time.time()),
                        datatype,
                        snr,
                        offset,
                        frequency,
                    ]
                )
                break


#    for idx, item in enumerate(static.HEARD_STATIONS):
#        if dxcallsign in item:
#            item = [dxcallsign, int(time.time())]
#            static.HEARD_STATIONS[idx] = item


def callsign_to_bytes(callsign):
    """

    Args:
      callsign:

    Returns:

    """
    # http://www.aprs.org/aprs11/SSIDs.txt
    # -0 Your primary station usually fixed and message capable
    # -1 generic additional station, digi, mobile, wx, etc
    # -2 generic additional station, digi, mobile, wx, etc
    # -3 generic additional station, digi, mobile, wx, etc
    # -4 generic additional station, digi, mobile, wx, etc
    # -5 Other networks (Dstar, Iphones, Androids, Blackberry's etc)
    # -6 Special activity, Satellite ops, camping or 6 meters, etc
    # -7 walkie talkies, HT's or other human portable
    # -8 boats, sailboats, RV's or second main mobile
    # -9 Primary Mobile (usually message capable)
    # -10 internet, Igates, echolink, winlink, AVRS, APRN, etc
    # -11 balloons, aircraft, spacecraft, etc
    # -12 APRStt, DTMF, RFID, devices, one-way trackers*, etc
    # -13 Weather stations
    # -14 Truckers or generally full time drivers
    # -15 generic additional station, digi, mobile, wx, etc

    # try converting to bytestring if possible type string
    try:
        callsign = bytes(callsign, "utf-8")
    except:
        pass

    # we need to do this step to reduce the needed paypload by the callsign ( stripping "-" out of the callsign )
    callsign = callsign.split(b"-")
    try:
        ssid = int(callsign[1])
    except:
        ssid = 0

    callsign = callsign[0]

    bytestring = bytearray(8)
    bytestring[: len(callsign)] = callsign
    bytestring[7:8] = bytes([ssid])

    return bytes(bytestring)


def bytes_to_callsign(bytestring):
    """

    Args:
      bytestring:

    Returns:

    """

    # http://www.aprs.org/aprs11/SSIDs.txt
    # -0 Your primary station usually fixed and message capable
    # -1 generic additional station, digi, mobile, wx, etc
    # -2 generic additional station, digi, mobile, wx, etc
    # -3 generic additional station, digi, mobile, wx, etc
    # -4 generic additional station, digi, mobile, wx, etc
    # -5 Other networks (Dstar, Iphones, Androids, Blackberry's etc)
    # -6 Special activity, Satellite ops, camping or 6 meters, etc
    # -7 walkie talkies, HT's or other human portable
    # -8 boats, sailboats, RV's or second main mobile
    # -9 Primary Mobile (usually message capable)
    # -10 internet, Igates, echolink, winlink, AVRS, APRN, etc
    # -11 balloons, aircraft, spacecraft, etc
    # -12 APRStt, DTMF, RFID, devices, one-way trackers*, etc
    # -13 Weather stations
    # -14 Truckers or generally full time drivers
    # -15 generic additional station, digi, mobile, wx, etc

    # we need to do this step to reduce the needed paypload by the callsign ( stripping "-" out of the callsign )

    callsign = bytes(bytestring[:7])
    callsign = callsign.rstrip(b"\x00")
    ssid = int.from_bytes(bytes(bytestring[7:8]), "big")

    callsign = callsign + b"-"
    callsign = callsign.decode("utf-8")
    callsign = callsign + str(ssid)
    callsign = callsign.encode("utf-8")

    return bytes(callsign)


def check_callsign(callsign: bytes, crc_to_check: bytes):
    """
    Funktion to check a crc against a callsign to calculate the ssid by generating crc until we got it

    Args:
      callsign: Callsign which we want to check
      crc_to_check: The CRC which we want the callsign to check against

    Returns:
        [True, Callsign + SSID]
        False
    """

    crc_algorithm = crcengine.new("crc16-ccitt-false")  # load crc16 library

    try:
        callsign = callsign.split(b"-")
        callsign = callsign[0]  # we want the callsign without SSID

    except:
        callsign = callsign

    print(static.SSID_LIST)
    for ssid in static.SSID_LIST:
        print(ssid)
    for ssid in static.SSID_LIST:
        # for ssid in range(0,254):
        call_with_ssid = bytearray(callsign)
        call_with_ssid.extend("-".encode("utf-8"))
        call_with_ssid.extend(str(ssid).encode("utf-8"))

        callsign_crc = get_crc_16(call_with_ssid)

        if callsign_crc == crc_to_check:
            print(call_with_ssid)
            return [True, bytes(call_with_ssid)]

    return [False, ""]