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 structlog

import static


def wait(seconds: float) -> bool:
    """

    Args:
        seconds:

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

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

def get_crc_8(data) -> bytes:
    """Author: DJ2LS

    Get the CRC8 of a byte string

    param: data = bytes()

    Args:
        data:

    Returns:
        CRC-8 (CCITT) of the provided data as bytes
    """
    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) -> bytes:
    """Author: DJ2LS

    Get the CRC16 of a byte string

    param: data = bytes()

    Args:
        data:

    Returns:
        CRC-16 (CCITT) of the provided data as bytes
    """
    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_24(data) -> bytes:
    """Author: DJ2LS

    Get the CRC24-OPENPGP of a byte string
    https://github.com/GardenTools/CrcEngine#examples

    param: data = bytes()

    Args:
        data:

    Returns:
        CRC-24 (OpenPGP) of the provided data as bytes
    """
    crc_algorithm = crcengine.create(0x864cfb, 24, 0xb704ce, ref_in=False,
                               ref_out=False, xor_out=0,
                               name='crc-24-openpgp')
    crc_data = crc_algorithm(data)
    crc_data = crc_data.to_bytes(3, byteorder='big')
    return crc_data

def get_crc_32(data: bytes) -> bytes:
    """Author: DJ2LS

    Get the CRC32 of a byte string

    param: data = bytes()

    Args:
      data:

    Returns:
        CRC-32 of the provided data as bytes
    """
    crc_algorithm = crcengine.new('crc32')  # load crc32 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:
        Nothing
    """
    # 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(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) -> bytes:
    """

    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 TypeError as e:
        structlog.get_logger("structlog").debug("[HLP] callsign_to_bytes: Exception converting callsign to bytes:", e=e)
        pass

    # Need this step to reduce the needed payload by the callsign (stripping "-" out of the callsign)
    callsign = callsign.split(b'-')
    ssid = 0
    try:
        ssid = int(callsign[1])
    except IndexError as e:
        structlog.get_logger("structlog").debug("[HLP] callsign_to_bytes: Error callsign SSID to integer:", e=e)

    #callsign = callsign[0]
    #bytestring = bytearray(8)
    #bytestring[:len(callsign)] = callsign
    #bytestring[7:8] = bytes([ssid])

    # ---- callsign with encoding always 6 bytes long
    callsign = callsign[0].decode("utf-8")
    ssid = bytes([ssid]).decode("utf-8")
    return encode_call(callsign + ssid)
    #return bytes(bytestring)

def bytes_to_callsign(bytestring: bytes) -> bytes:
    """
    Convert our callsign, received by a frame to a callsign in a human readable format

    Args:
        bytestring:

    Returns:
        bytes
    """
    # 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)
    '''
    decoded = decode_call(bytestring)
    callsign = decoded[:-1]
    ssid = ord(bytes(decoded[-1], "utf-8"))
    return bytes(f"{callsign}-{ssid}", "utf-8")

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
    """

    # print(callsign)
    structlog.get_logger("structlog").debug("[HLP] check_callsign: Checking:", callsign=callsign)
    try:
        # We want the callsign without SSID
        callsign = callsign.split(b'-')[0]

    except Exception as e:
        structlog.get_logger("structlog").debug("[HLP] check_callsign: Error callsign SSIG to integer:", e=e)

    for ssid in static.SSID_LIST:
        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_24(call_with_ssid)

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

    return [False, ""]

def encode_grid(grid):
    """
    @auther: DB1UJ
    Args:
        grid:string: maidenhead QTH locater [a-r][a-r][0-9][0-9][a-x][a-x]
    Returns:
        4 bytes contains 26 bit valid data with encoded grid locator
    """
    out_code_word = 0

    grid = grid.upper() # upper case to be save

    int_first = ord(grid[0]) - 65 # -65 offset for 'A' become zero, utf8 table
    int_sec   = ord(grid[1]) - 65 # -65 offset for 'A' become zero, utf8 table

    int_val = (int_first * 18) + int_sec # encode for modulo devision, 2 numbers in 1

    out_code_word = (int_val & 0b111111111) # only 9 bit LSB A - R * A - R is needed
    out_code_word <<= 9 # shift 9 bit left having space next bits, letter A-R * A-R

    int_val = int(grid[2:4]) # number string to number int, highest value 99
    out_code_word |= (int_val & 0b1111111) # using bit OR to add new value
    out_code_word <<= 7 # shift 7 bit left having space next bits, letter A-X

    int_val = ord(grid[4]) - 65 # -65 offset for 'A' become zero, utf8 table
    out_code_word |= (int_val & 0b11111) # using bit OR to add new value
    out_code_word <<= 5 # shift 5 bit left having space next bits, letter A-X

    int_val = ord(grid[5]) - 65 # -65 offset for 'A' become zero, utf8 table
    out_code_word |= (int_val & 0b11111) # using bit OR to add new value

    return out_code_word.to_bytes(length=4, byteorder='big')

def decode_grid(b_code_word:bytes):
    """
    @auther: DB1UJ
    Args:
        b_code_word:bytes: 4 bytes with 26 bit valid data LSB
    Returns:
        grid:str: upper case maidenhead QTH locater [A-R][A-R][0-9][0-9][A-X][A-X]
    """
    code_word = int.from_bytes(b_code_word, byteorder='big', signed=False)

    grid = chr((code_word & 0b11111) + 65)
    code_word >>= 5

    grid = chr((code_word & 0b11111) + 65) + grid
    code_word >>= 7

    grid = str(int(code_word & 0b1111111)) + grid
    if (code_word & 0b1111111) < 10:
        grid = f'0{grid}'
    code_word >>= 9

    int_val = int(code_word & 0b111111111)
    int_first, int_sec = divmod(int_val, 18)
    # int_first = int_val // 18
    # int_sec   = int_val % 18
    grid = chr(int(int_first) + 65) + chr(int(int_sec) + 65) + grid

    return grid

def encode_call(call):
    """
    @auther: DB1UJ
    Args:
        call:string: ham radio call sign [A-Z,0-9], last char SSID 0-63

    Returns:
        6 bytes contains 6 bits/sign encoded 8 char call sign with binary SSID (only upper letters + numbers, SSID)
    """
    out_code_word = 0

    call = call.upper() # upper case to be save

    for x in call:
        int_val = ord(x) - 48 # -48 reduce bits, begin with first number utf8 table
        out_code_word <<= 6 # shift left 6 bit, making space for a new char
        out_code_word |= (int_val & 0b111111) # bit OR adds the new char, masked with AND 0b111111
    out_code_word >>= 6 # clean last char
    out_code_word <<= 6 # make clean space
    out_code_word |= (ord(call[-1]) & 0b111111) # add the SSID uncoded only 0 - 63

    return out_code_word.to_bytes(length=6, byteorder='big')

def decode_call(b_code_word:bytes):
    """
    @auther: DB1UJ
    Args:
        b_code_word:bytes: 6 bytes with 6 bits/sign valid data char signs LSB

    Returns:
        call:str: upper case ham radio call sign [A-Z,0-9] + binary SSID
    """
    code_word = int.from_bytes(b_code_word, byteorder='big', signed=False)
    ssid = chr(code_word & 0b111111) # save the uncoded binary SSID

    call = str()
    while code_word != 0:
        call = chr((code_word & 0b111111)+48) + call
        code_word >>= 6

    call = call[:-1] + ssid # remove the last char from call and replace with SSID

    return call