pysim/pySim/transport/__init__.py

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

""" pySim: PCSC reader transport link base
"""

import os
import abc
import argparse
from typing import Optional, Tuple
from construct import Construct
from osmocom.utils import b2h, h2b, i2h, Hexstr

from pySim.exceptions import *
from pySim.utils import SwHexstr, SwMatchstr, ResTuple, sw_match, parse_command_apdu
from pySim.cat import ProactiveCommand, CommandDetails, DeviceIdentities, Result

#
# Copyright (C) 2009-2010  Sylvain Munaut <tnt@246tNt.com>
# Copyright (C) 2021-2023 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/>.
#


class ApduTracer:
    def trace_command(self, cmd):
        pass

    def trace_response(self, cmd, sw, resp):
        pass

    def trace_reset(self):
        pass

class StdoutApduTracer(ApduTracer):
    """Minimalistic APDU tracer, printing commands to stdout."""
    def trace_response(self, cmd, sw, resp):
        print("-> %s %s" % (cmd[:10], cmd[10:]))
        print("<- %s: %s" % (sw, resp))

    def trace_reset(self):
        print("-- RESET")

class ProactiveHandler(abc.ABC):
    """Abstract base class representing the interface of some code that handles
    the proactive commands, as returned by the card in responses to the FETCH
    command."""
    def receive_fetch_raw(self, pcmd: ProactiveCommand, parsed: Hexstr):
        # try to find a generic handler like handle_SendShortMessage
        handle_name = 'handle_%s' % type(parsed).__name__
        if hasattr(self, handle_name):
            handler = getattr(self, handle_name)
            return handler(pcmd.decoded)
        # fall back to common handler
        return self.receive_fetch(pcmd)

    def receive_fetch(self, pcmd: ProactiveCommand):
        """Default handler for not otherwise handled proactive commands."""
        raise NotImplementedError('No handler method for %s' % pcmd.decoded)

    def prepare_response(self, pcmd: ProactiveCommand, general_result: str = 'performed_successfully'):
        # The Command Details are echoed from the command that has been processed.
        (command_details,) = [c for c in pcmd.children if isinstance(c, CommandDetails)]
        # invert the device identities
        (command_dev_ids,) = [c for c in pcmd.children if isinstance(c, DeviceIdentities)]
        rsp_dev_ids = DeviceIdentities()
        rsp_dev_ids.from_dict({'device_identities': {
                                    'dest_dev_id': command_dev_ids.decoded['source_dev_id'],
                                    'source_dev_id': command_dev_ids.decoded['dest_dev_id']}})
        result = Result()
        result.from_dict({'result': {'general_result': general_result, 'additional_information': ''}})
        return [command_details, rsp_dev_ids, result]

class LinkBase(abc.ABC):
    """Base class for link/transport to card."""

    def __init__(self, sw_interpreter=None, apdu_tracer: Optional[ApduTracer]=None,
                 proactive_handler: Optional[ProactiveHandler]=None):
        self.sw_interpreter = sw_interpreter
        self.apdu_tracer = apdu_tracer
        self.proactive_handler = proactive_handler
        self.apdu_strict = False

    @abc.abstractmethod
    def __str__(self) -> str:
        """Implementation specific method for printing an information to identify the device."""

    @abc.abstractmethod
    def _send_apdu(self, apdu: Hexstr) -> ResTuple:
        """Implementation specific method for sending the APDU. This method must accept APDUs as defined in
        ISO/IEC 7816-3, section 12.1 """

    def set_sw_interpreter(self, interp):
        """Set an (optional) status word interpreter."""
        self.sw_interpreter = interp

    @abc.abstractmethod
    def wait_for_card(self, timeout: Optional[int] = None, newcardonly: bool = False):
        """Wait for a card and connect to it

        Args:
           timeout : Maximum wait time in seconds (None=no timeout)
           newcardonly : Should we wait for a new card, or an already inserted one ?
        """

    @abc.abstractmethod
    def connect(self):
        """Connect to a card immediately
        """

    @abc.abstractmethod
    def get_atr(self) -> Hexstr:
        """Retrieve card ATR
        """

    @abc.abstractmethod
    def disconnect(self):
        """Disconnect from card
        """

    @abc.abstractmethod
    def _reset_card(self):
        """Resets the card (power down/up)
        """

    def reset_card(self):
        """Resets the card (power down/up)
        """
        if self.apdu_tracer:
            self.apdu_tracer.trace_reset()
        return self._reset_card()

    def send_apdu(self, apdu: Hexstr) -> ResTuple:
        """Sends an APDU with minimal processing

        Args:
           apdu : string of hexadecimal characters (ex. "A0A40000023F00", must comply to ISO/IEC 7816-3, section 12.1)
        Returns:
           tuple(data, sw), where
                        data : string (in hex) of returned data (ex. "074F4EFFFF")
                        sw   : string (in hex) of status word (ex. "9000")
        """

        # To make sure that no invalid APDUs can be passed further down into the transport layer, we parse the APDU.
        (case, _lc, _le, _data) = parse_command_apdu(h2b(apdu))

        if self.apdu_tracer:
            self.apdu_tracer.trace_command(apdu)

        # Handover APDU to concrete transport layer implementation
        (data, sw) = self._send_apdu(apdu)

        if self.apdu_tracer:
            self.apdu_tracer.trace_response(apdu, sw, data)

        # The APDU case (See aso ISO/IEC 7816-3, table 12) dictates if we should receive a response or not. If we
        # receive a response in an APDU case that does not allow the reception of a respnse we print a warning to
        # make the user/caller aware of the problem. Since the transaction is over at this point and data was received
        # we count it as a successful transaction anyway, even though the spec was violated. The problem is most likely
        # caused by a missing Le field in the APDU. This is an error that the caller/user should correct to avoid
        # problems at some later point when a different transport protocol or transport layer implementation is used.
        # All APDUs passed to this function must comply to ISO/IEC 7816-3, section 12.
        if len(data) > 0 and (case == 3 or case == 1):
            exeption_str = 'received unexpected response data, incorrect APDU-case ' + \
            '(%d, should be %d, missing Le field?)!' % (case, case + 1)
            if self.apdu_strict:
                raise ValueError(exeption_str)
            else:
                print('Warning: %s' % exeption_str)

        return (data, sw)

    def send_apdu_checksw(self, apdu: Hexstr, sw: SwMatchstr = "9000") -> ResTuple:
        """Sends an APDU and check returned SW

        Args:
           apdu : string of hexadecimal characters (ex. "A0A40000023F00", must comply to ISO/IEC 7816-3, section 12.1)
           sw : string of 4 hexadecimal characters (ex. "9000"). The user may mask out certain
                        digits using a '?' to add some ambiguity if needed.
        Returns:
                tuple(data, sw), where
                        data : string (in hex) of returned data (ex. "074F4EFFFF")
                        sw   : string (in hex) of status word (ex. "9000")
        """
        rv = self.send_apdu(apdu)
        last_sw = rv[1]

        while sw == '9000' and sw_match(last_sw, '91xx'):
            # It *was* successful after all -- the extra pieces FETCH handled
            # need not concern the caller.
            rv = (rv[0], '9000')
            # proactive sim as per TS 102 221 Setion 7.4.2
            # TODO: Check SW manually to avoid recursing on the stack (provided this piece of code stays in this place)
            fetch_rv = self.send_apdu_checksw('80120000' + last_sw[2:], sw)
            # Setting this in case we later decide not to send a terminal
            # response immediately unconditionally -- the card may still have
            # something pending even though the last command was not processed
            # yet.
            last_sw = fetch_rv[1]
            # parse the proactive command
            pcmd = ProactiveCommand()
            parsed = pcmd.from_tlv(h2b(fetch_rv[0]))
            print("FETCH: %s (%s)" % (fetch_rv[0], type(parsed).__name__))
            if self.proactive_handler:
                # Extension point: If this does return a list of TLV objects,
                # they could be appended after the Result; if the first is a
                # Result, that cuold replace the one built here.
                ti_list = self.proactive_handler.receive_fetch_raw(pcmd, parsed)
                if not ti_list:
                    ti_list = self.proactive_handler.prepare_response(pcmd, 'FIXME')
            else:
                ti_list = self.proactive_handler.prepare_response(pcmd, 'command_beyond_terminal_capability')

            # Send response immediately, thus also flushing out any further
            # proactive commands that the card already wants to send
            #
            # Structure as per TS 102 223 V4.4.0 Section 6.8

            # Testing hint: The value of tail does not influence the behavior
            # of an SJA2 that sent ans SMS, so this is implemented only
            # following TS 102 223, and not fully tested.
            ti_list_bin = [x.to_tlv() for x in ti_list]
            tail = b''.join(ti_list_bin)
            # Testing hint: In contrast to the above, this part is positively
            # essential to get the SJA2 to provide the later parts of a
            # multipart SMS in response to an OTA RFM command.
            terminal_response = '80140000' + b2h(len(tail).to_bytes(1, 'big') + tail)

            terminal_response_rv = self.send_apdu(terminal_response)
            last_sw = terminal_response_rv[1]

        if not sw_match(rv[1], sw):
            raise SwMatchError(rv[1], sw.lower(), self.sw_interpreter)
        return rv


class LinkBaseTpdu(LinkBase):

    # Use the T=0 TPDU format by default as this is the most commonly used transport protocol.
    protocol = 0

    def set_tpdu_format(self, protocol: int):
        """Set TPDU format. Each transport protocol has its specific TPDU format. This method allows the
        concrete transport layer implementation to set the TPDU format it expects. (This method must not be
        called by higher layers. Switching the TPDU format does not switch the transport protocol that the
        reader uses on the wire)

        Args:
           protocol : number of the transport protocol used. (0 => T=0, 1 => T=1)
        """
        self.protocol = protocol

    @abc.abstractmethod
    def send_tpdu(self, tpdu: Hexstr) -> ResTuple:
        """Implementation specific method for sending the resulting TPDU. This method must accept TPDUs as defined in
        ETSI TS 102 221, section 7.3.1 and 7.3.2, depending on the protocol selected. """

    def _send_apdu(self, apdu: Hexstr) -> ResTuple:
        """Transforms APDU into a TPDU and sends it. The response TPDU is returned as APDU back to the caller.

        Args:
           apdu : string of hexadecimal characters (eg. "A0A40000023F00", must comply to ISO/IEC 7816-3, section 12)
        Returns:
           tuple(data, sw), where
                        data : string (in hex) of returned data (ex. "074F4EFFFF")
                        sw   : string (in hex) of status word (ex. "9000")
        """

        if self.protocol == 0:
            return self.__send_apdu_T0(apdu)
        elif self.protocol == 1:
            return self.__send_apdu_transparent(apdu)
        raise ValueError('unspported protocol selected (T=%d)' % self.protocol)

    def __send_apdu_T0(self, apdu: Hexstr) -> ResTuple:
        # Transform the given APDU to the T=0 TPDU format and send it. Automatically fetch the response (case #4 APDUs)
        # (see also ETSI TS 102 221, section 7.3.1.1)

        # Transform APDU to T=0 TPDU (see also ETSI TS 102 221, section 7.3.1)
        (case, _lc, _le, _data) = parse_command_apdu(h2b(apdu))

        if case == 1:
            # Attach an Le field to all case #1 APDUs (see also ETSI TS 102 221, section 7.3.1.1.1)
            tpdu = apdu + '00'
        elif case == 4:
            # Remove the Le field from all case #4 APDUs (see also ETSI TS 102 221, section 7.3.1.1.4)
            tpdu = apdu[:-2]
        else:
            tpdu = apdu

        prev_tpdu = tpdu
        data, sw = self.send_tpdu(tpdu)

        # When we have sent the first APDU, the SW may indicate that there are response bytes
        # available. There are two SWs commonly used for this 9fxx (sim) and 61xx (usim), where
        # xx is the number of response bytes available.
        # See also:
        if sw is not None:
            while (sw[0:2] in ['9f', '61', '62', '63']):
                # SW1=9F: 3GPP TS 51.011 9.4.1, Responses to commands which are correctly executed
                # SW1=61: ISO/IEC 7816-4, Table 5 — General meaning of the interindustry values of SW1-SW2
                # SW1=62: ETSI TS 102 221 7.3.1.1.4 Clause 4b): 62xx, 63xx, 9xxx != 9000
                tpdu_gr = tpdu[0:2] + 'c00000' + sw[2:4]
                prev_tpdu = tpdu_gr
                d, sw = self.send_tpdu(tpdu_gr)
                data += d
            if sw[0:2] == '6c':
                # SW1=6C: ETSI TS 102 221 Table 7.1: Procedure byte coding
                tpdu_gr = prev_tpdu[0:8] + sw[2:4]
                data, sw = self.send_tpdu(tpdu_gr)

        return data, sw

    def __send_apdu_transparent(self, apdu: Hexstr) -> ResTuple:
        # In cases where the TPDU format is the same as the APDU format, we may pass the given APDU through without modification
        # (This is the case for T=1, see also  ETSI TS 102 221, section 7.3.2.0.)
        return self.send_tpdu(apdu)

def argparse_add_reader_args(arg_parser: argparse.ArgumentParser):
    """Add all reader related arguments to the given argparse.Argumentparser instance."""
    from pySim.transport.serial import SerialSimLink
    from pySim.transport.pcsc import PcscSimLink
    from pySim.transport.modem_atcmd import ModemATCommandLink
    from pySim.transport.calypso import CalypsoSimLink

    SerialSimLink.argparse_add_reader_args(arg_parser)
    PcscSimLink.argparse_add_reader_args(arg_parser)
    ModemATCommandLink.argparse_add_reader_args(arg_parser)
    CalypsoSimLink.argparse_add_reader_args(arg_parser)
    arg_parser.add_argument('--apdu-trace', action='store_true',
                            help='Trace the command/response APDUs exchanged with the card')

    return arg_parser


def init_reader(opts, **kwargs) -> LinkBase:
    """
    Init card reader driver
    """
    if opts.apdu_trace and not 'apdu_tracer' in kwargs:
        kwargs['apdu_tracer'] = StdoutApduTracer()

    if opts.pcsc_dev is not None or opts.pcsc_regex is not None:
        from pySim.transport.pcsc import PcscSimLink
        sl = PcscSimLink(opts, **kwargs)
    elif opts.osmocon_sock is not None:
        from pySim.transport.calypso import CalypsoSimLink
        sl = CalypsoSimLink(opts, **kwargs)
    elif opts.modem_dev is not None:
        from pySim.transport.modem_atcmd import ModemATCommandLink
        sl = ModemATCommandLink(opts, **kwargs)
    else:  # Serial reader is default
        print("No reader/driver specified; falling back to default (Serial reader)")
        from pySim.transport.serial import SerialSimLink
        sl = SerialSimLink(opts, **kwargs)

    if os.environ.get('PYSIM_INTEGRATION_TEST') == "1":
        print("Using %s reader interface" % (sl.name))
    else:
        print("Using reader %s" % sl)

    return sl