pySim/transport/serial.py

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

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

import serial
import time
import os.path
from typing import Optional

from pySim.exceptions import NoCardError, ProtocolError
from pySim.transport import LinkBase
from pySim.utils import h2b, b2h, Hexstr, ResTuple


class SerialSimLink(LinkBase):
    """ pySim: Transport Link for serial (RS232) based readers included with simcard"""

    def __init__(self, device: str = '/dev/ttyUSB0', baudrate: int = 9600, rst: str = '-rts',
                 debug: bool = False, **kwargs):
        super().__init__(**kwargs)
        if not os.path.exists(device):
            raise ValueError("device file %s does not exist -- abort" % device)
        self._sl = serial.Serial(
            port=device,
            parity=serial.PARITY_EVEN,
            bytesize=serial.EIGHTBITS,
            stopbits=serial.STOPBITS_TWO,
            timeout=1,
            xonxoff=0,
            rtscts=0,
            baudrate=baudrate,
        )
        self._rst_pin = rst
        self._debug = debug
        self._atr = None

    def __del__(self):
        if (hasattr(self, "_sl")):
            self._sl.close()

    def wait_for_card(self, timeout: Optional[int] = None, newcardonly: bool = False):
        # Direct try
        existing = False

        try:
            self.reset_card()
            if not newcardonly:
                return
            else:
                existing = True
        except NoCardError:
            pass

        # Poll ...
        mt = time.time() + timeout if timeout is not None else None
        pe = 0

        while (mt is None) or (time.time() < mt):
            try:
                time.sleep(0.5)
                self.reset_card()
                if not existing:
                    return
            except NoCardError:
                existing = False
            except ProtocolError:
                if existing:
                    existing = False
                else:
                    # Tolerate a couple of protocol error ... can happen if
                    # we try when the card is 'half' inserted
                    pe += 1
                    if (pe > 2):
                        raise

        # Timed out ...
        raise NoCardError()

    def connect(self):
        self.reset_card()

    def get_atr(self) -> Hexstr:
        return self._atr

    def disconnect(self):
        pass  # Nothing to do really ...

    def reset_card(self):
        rv = self._reset_card()
        if rv == 0:
            raise NoCardError()
        elif rv < 0:
            raise ProtocolError()
        return rv

    def _reset_card(self):
        self._atr = None
        rst_meth_map = {
            'rts': self._sl.setRTS,
            'dtr': self._sl.setDTR,
        }
        rst_val_map = {'+': 0, '-': 1}

        try:
            rst_meth = rst_meth_map[self._rst_pin[1:]]
            rst_val = rst_val_map[self._rst_pin[0]]
        except:
            raise ValueError('Invalid reset pin %s' % self._rst_pin)

        rst_meth(rst_val)
        time.sleep(0.1)  # 100 ms
        self._sl.flushInput()
        rst_meth(rst_val ^ 1)

        b = self._rx_byte()
        if not b:
            return 0
        if ord(b) != 0x3b:
            return -1
        self._dbg_print("TS: 0x%x Direct convention" % ord(b))

        while ord(b) == 0x3b:
            b = self._rx_byte()

        if not b:
            return -1
        t0 = ord(b)
        self._dbg_print("T0: 0x%x" % t0)
        self._atr = [0x3b, ord(b)]

        for i in range(4):
            if t0 & (0x10 << i):
                b = self._rx_byte()
                self._atr.append(ord(b))
                self._dbg_print("T%si = %x" % (chr(ord('A')+i), ord(b)))

        for i in range(0, t0 & 0xf):
            b = self._rx_byte()
            self._atr.append(ord(b))
            self._dbg_print("Historical = %x" % ord(b))

        while True:
            x = self._rx_byte()
            if not x:
                break
            self._atr.append(ord(x))
            self._dbg_print("Extra: %x" % ord(x))

        return 1

    def _dbg_print(self, s):
        if self._debug:
            print(s)

    def _tx_byte(self, b):
        self._sl.write(b)
        r = self._sl.read()
        if r != b:  # TX and RX are tied, so we must clear the echo
            raise ProtocolError("Bad echo value. Expected %02x, got %s)" % (
                ord(b), '%02x' % ord(r) if r else '(nil)'))

    def _tx_string(self, s):
        """This is only safe if it's guaranteed the card won't send any data
        during the time of tx of the string !!!"""
        self._sl.write(s)
        r = self._sl.read(len(s))
        if r != s:  # TX and RX are tied, so we must clear the echo
            raise ProtocolError(
                "Bad echo value (Expected: %s, got %s)" % (b2h(s), b2h(r)))

    def _rx_byte(self):
        return self._sl.read()

    def _send_apdu_raw(self, pdu: Hexstr) -> ResTuple:

        pdu = h2b(pdu)
        data_len = pdu[4]  # P3

        # Send first CLASS,INS,P1,P2,P3
        self._tx_string(pdu[0:5])

        # Wait ack which can be
        #  - INS: Command acked -> go ahead
        #  - 0x60: NULL, just wait some more
        #  - SW1: The card can apparently proceed ...
        while True:
            b = self._rx_byte()
            if ord(b) == pdu[1]:
                break
            elif b != '\x60':
                # Ok, it 'could' be SW1
                sw1 = b
                sw2 = self._rx_byte()
                nil = self._rx_byte()
                if (sw2 and not nil):
                    return '', b2h(sw1+sw2)

                raise ProtocolError()

        # Send data (if any)
        if len(pdu) > 5:
            self._tx_string(pdu[5:])

        # Receive data (including SW !)
        #  length = [P3 - tx_data (=len(pdu)-len(hdr)) + 2 (SW1//2) ]
        to_recv = data_len - len(pdu) + 5 + 2

        data = bytes(0)
        while (len(data) < to_recv):
            b = self._rx_byte()
            if (to_recv == 2) and (b == '\x60'):  # Ignore NIL if we have no RX data (hack ?)
                continue
            if not b:
                break
            data += b

        # Split datafield from SW
        if len(data) < 2:
            return None, None
        sw = data[-2:]
        data = data[0:-2]

        # Return value
        return b2h(data), b2h(sw)

    def __str__(self):
        return "serial:%s" % (self._sl.name)