utils: move enc_msisdn and dec_msisdn to legacy/utils.py

We now have a construct based encoder/decoder for the record content
of EF.MSISDN. This means that we do not need the functions enc_msisdn
and dec_msisdn in the non-legacy code anymore. We can now move both
to legacy/utils.py.

Related: OS#5714
Change-Id: I19ec8ba14551ec282fc0cc12ae2f6d528bdfc527

pySim/utils.py

@@ -341,86 +341,6 @@ def derive_mnc(digit1: int, digit2: int, digit3: int = 0x0f) -> int:
 
     return mnc
 
-
-def dec_msisdn(ef_msisdn: Hexstr) -> Optional[Tuple[int, int, Optional[str]]]:
-    """
-    Decode MSISDN from EF.MSISDN or EF.ADN (same structure).
-    See 3GPP TS 31.102, section 4.2.26 and 4.4.2.3.
-    """
-
-    # Convert from str to (kind of) 'bytes'
-    ef_msisdn = h2b(ef_msisdn)
-
-    # Make sure mandatory fields are present
-    if len(ef_msisdn) < 14:
-        raise ValueError("EF.MSISDN is too short")
-
-    # Skip optional Alpha Identifier
-    xlen = len(ef_msisdn) - 14
-    msisdn_lhv = ef_msisdn[xlen:]
-
-    # Parse the length (in bytes) of the BCD encoded number
-    bcd_len = msisdn_lhv[0]
-    # BCD length = length of dial num (max. 10 bytes) + 1 byte ToN and NPI
-    if bcd_len == 0xff:
-        return None
-    elif bcd_len > 11 or bcd_len < 1:
-        raise ValueError(
-            "Length of MSISDN (%d bytes) is out of range" % bcd_len)
-
-    # Parse ToN / NPI
-    ton = (msisdn_lhv[1] >> 4) & 0x07
-    npi = msisdn_lhv[1] & 0x0f
-    bcd_len -= 1
-
-    # No MSISDN?
-    if not bcd_len:
-        return (npi, ton, None)
-
-    msisdn = swap_nibbles(b2h(msisdn_lhv[2:][:bcd_len])).rstrip('f')
-    # International number 10.5.118/3GPP TS 24.008
-    if ton == 0x01:
-        msisdn = '+' + msisdn
-
-    return (npi, ton, msisdn)
-
-
-def enc_msisdn(msisdn: str, npi: int = 0x01, ton: int = 0x03) -> Hexstr:
-    """
-    Encode MSISDN as LHV so it can be stored to EF.MSISDN.
-    See 3GPP TS 31.102, section 4.2.26 and 4.4.2.3. (The result
-    will not contain the optional Alpha Identifier at the beginning.)
-
-    Default NPI / ToN values:
-      - NPI: ISDN / telephony numbering plan (E.164 / E.163),
-      - ToN: network specific or international number (if starts with '+').
-    """
-
-    # If no MSISDN is supplied then encode the file contents as all "ff"
-    if msisdn in ["", "+"]:
-        return "ff" * 14
-
-    # Leading '+' indicates International Number
-    if msisdn[0] == '+':
-        msisdn = msisdn[1:]
-        ton = 0x01
-
-    # An MSISDN must not exceed 20 digits
-    if len(msisdn) > 20:
-        raise ValueError("msisdn must not be longer than 20 digits")
-
-    # Append 'f' padding if number of digits is odd
-    if len(msisdn) % 2 > 0:
-        msisdn += 'f'
-
-    # BCD length also includes NPI/ToN header
-    bcd_len = len(msisdn) // 2 + 1
-    npi_ton = (npi & 0x0f) | ((ton & 0x07) << 4) | 0x80
-    bcd = rpad(swap_nibbles(msisdn), 10 * 2)  # pad to 10 octets
-
-    return ('%02x' % bcd_len) + ('%02x' % npi_ton) + bcd + ("ff" * 2)
-
-
 def sanitize_pin_adm(pin_adm, pin_adm_hex=None) -> Hexstr:
     """
     The ADM pin can be supplied either in its hexadecimal form or as