pySim/legacy/utils.py

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

""" pySim: various utilities only used by legacy tools (pySim-{prog,read})
"""

# Copyright (C) 2009-2010  Sylvain Munaut <tnt@246tNt.com>
# Copyright (C) 2021 Harald Welte <laforge@osmocom.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

from pySim.utils import Hexstr, rpad, enc_plmn
from pySim.utils import dec_xplmn_w_act, dec_xplmn, dec_mcc_from_plmn, dec_mnc_from_plmn

def hexstr_to_Nbytearr(s, nbytes):
    return [s[i:i+(nbytes*2)] for i in range(0, len(s), (nbytes*2))]

def format_xplmn_w_act(hexstr):
    s = ""
    for rec_data in hexstr_to_Nbytearr(hexstr, 5):
        rec_info = dec_xplmn_w_act(rec_data)
        if rec_info['mcc'] == "" and rec_info['mnc'] == "":
            rec_str = "unused"
        else:
            rec_str = "MCC: %s MNC: %s AcT: %s" % (
                rec_info['mcc'], rec_info['mnc'], ", ".join(rec_info['act']))
        s += "\t%s # %s\n" % (rec_data, rec_str)
    return s


def format_xplmn(hexstr: Hexstr) -> str:
    s = ""
    for rec_data in hexstr_to_Nbytearr(hexstr, 3):
        rec_info = dec_xplmn(rec_data)
        if not rec_info['mcc'] and not rec_info['mnc']:
            rec_str = "unused"
        else:
            rec_str = "MCC: %s MNC: %s" % (rec_info['mcc'], rec_info['mnc'])
        s += "\t%s # %s\n" % (rec_data, rec_str)
    return s


def format_ePDGSelection(hexstr):
    ePDGSelection_info_tag_chars = 2
    ePDGSelection_info_tag_str = hexstr[:2]
    s = ""
    # Minimum length
    len_chars = 2
    # TODO: Need to determine length properly - definite length support only
    # Inconsistency in spec: 3GPP TS 31.102 version 15.2.0 Release 15, 4.2.104
    # As per spec, length is 5n, n - number of PLMNs
    # But, each PLMN entry is made of PLMN (3 Bytes) + ePDG Priority (2 Bytes) + ePDG FQDN format (1 Byte)
    # Totalling to 6 Bytes, maybe length should be 6n
    len_str = hexstr[ePDGSelection_info_tag_chars:ePDGSelection_info_tag_chars+len_chars]

    # Not programmed scenario
    if int(len_str, 16) == 255 or int(ePDGSelection_info_tag_str, 16) == 255:
        len_chars = 0
        ePDGSelection_info_tag_chars = 0
    if len_str[0] == '8':
        # The bits 7 to 1 denotes the number of length octets if length > 127
        if int(len_str[1]) > 0:
            # Update number of length octets
            len_chars = len_chars * int(len_str[1])
            len_str = hexstr[ePDGSelection_info_tag_chars:len_chars]

    content_str = hexstr[ePDGSelection_info_tag_chars+len_chars:]
    # Right pad to prevent index out of range - multiple of 6 bytes
    content_str = rpad(content_str, len(content_str) +
                       (12 - (len(content_str) % 12)))
    for rec_data in hexstr_to_Nbytearr(content_str, 6):
        rec_info = dec_ePDGSelection(rec_data)
        if rec_info['mcc'] == 0xFFF and rec_info['mnc'] == 0xFFF:
            rec_str = "unused"
        else:
            rec_str = "MCC: %03d MNC: %03d ePDG Priority: %s ePDG FQDN format: %s" % \
                (rec_info['mcc'], rec_info['mnc'],
                 rec_info['epdg_priority'], rec_info['epdg_fqdn_format'])
        s += "\t%s # %s\n" % (rec_data, rec_str)
    return s

def enc_st(st, service, state=1):
    """
    Encodes the EF S/U/IST/EST and returns the updated Service Table

    Parameters:
            st - Current value of SIM/USIM/ISIM Service Table
            service - Service Number to encode as activated/de-activated
            state - 1 mean activate, 0 means de-activate

    Returns:
            s - Modified value of SIM/USIM/ISIM Service Table

    Default values:
            - state: 1 - Sets the particular Service bit to 1
    """
    st_bytes = [st[i:i+2] for i in range(0, len(st), 2)]

    s = ""
    # Check whether the requested service is present in each byte
    for i in range(0, len(st_bytes)):
        # Byte i contains info about Services num (8i+1) to num (8i+8)
        if service in range((8*i) + 1, (8*i) + 9):
            byte = int(st_bytes[i], 16)
            # Services in each byte are in order MSB to LSB
            # MSB - Service (8i+8)
            # LSB - Service (8i+1)
            mod_byte = 0x00
            # Copy bit by bit contents of byte to mod_byte with modified bit
            # for requested service
            for j in range(1, 9):
                mod_byte = mod_byte >> 1
                if service == (8*i) + j:
                    mod_byte = state == 1 and mod_byte | 0x80 or mod_byte & 0x7f
                else:
                    mod_byte = byte & 0x01 == 0x01 and mod_byte | 0x80 or mod_byte & 0x7f
                byte = byte >> 1

            s += ('%02x' % (mod_byte))
        else:
            s += st_bytes[i]

    return s


def dec_st(st, table="sim") -> str:
    """
    Parses the EF S/U/IST and prints the list of available services in EF S/U/IST
    """

    if table == "isim":
        from pySim.ts_31_103 import EF_IST_map
        lookup_map = EF_IST_map
    elif table == "usim":
        from pySim.ts_31_102 import EF_UST_map
        lookup_map = EF_UST_map
    else:
        from pySim.ts_51_011 import EF_SST_map
        lookup_map = EF_SST_map

    st_bytes = [st[i:i+2] for i in range(0, len(st), 2)]

    avail_st = ""
    # Get each byte and check for available services
    for i in range(0, len(st_bytes)):
        # Byte i contains info about Services num (8i+1) to num (8i+8)
        byte = int(st_bytes[i], 16)
        # Services in each byte are in order MSB to LSB
        # MSB - Service (8i+8)
        # LSB - Service (8i+1)
        for j in range(1, 9):
            if byte & 0x01 == 0x01 and ((8*i) + j in lookup_map):
                # Byte X contains info about Services num (8X-7) to num (8X)
                # bit = 1: service available
                # bit = 0: service not available
                avail_st += '\tService %d - %s\n' % (
                    (8*i) + j, lookup_map[(8*i) + j])
            byte = byte >> 1
    return avail_st


def enc_ePDGSelection(hexstr, mcc, mnc, epdg_priority='0001', epdg_fqdn_format='00'):
    """
    Encode ePDGSelection so it can be stored at EF.ePDGSelection or EF.ePDGSelectionEm.
    See 3GPP TS 31.102 version 15.2.0 Release 15, section 4.2.104 and 4.2.106.

    Default values:
            - epdg_priority: '0001' - 1st Priority
            - epdg_fqdn_format: '00' - Operator Identifier FQDN
    """

    plmn1 = enc_plmn(mcc, mnc) + epdg_priority + epdg_fqdn_format
    # TODO: Handle encoding of Length field for length more than 127 Bytes
    content = '80' + ('%02x' % (len(plmn1)//2)) + plmn1
    content = rpad(content, len(hexstr))
    return content


def dec_ePDGSelection(sixhexbytes):
    """
    Decode ePDGSelection to get EF.ePDGSelection or EF.ePDGSelectionEm.
    See 3GPP TS 31.102 version 15.2.0 Release 15, section 4.2.104 and 4.2.106.
    """

    res = {'mcc': 0, 'mnc': 0, 'epdg_priority': 0, 'epdg_fqdn_format': ''}
    plmn_chars = 6
    epdg_priority_chars = 4
    epdg_fqdn_format_chars = 2
    # first three bytes (six ascii hex chars)
    plmn_str = sixhexbytes[:plmn_chars]
    # two bytes after first three bytes
    epdg_priority_str = sixhexbytes[plmn_chars:plmn_chars +
                                    epdg_priority_chars]
    # one byte after first five bytes
    epdg_fqdn_format_str = sixhexbytes[plmn_chars +
                                       epdg_priority_chars:plmn_chars + epdg_priority_chars + epdg_fqdn_format_chars]
    res['mcc'] = dec_mcc_from_plmn(plmn_str)
    res['mnc'] = dec_mnc_from_plmn(plmn_str)
    res['epdg_priority'] = epdg_priority_str
    res['epdg_fqdn_format'] = epdg_fqdn_format_str == '00' and 'Operator Identifier FQDN' or 'Location based FQDN'
    return res