edcd62435d
The implementations that inheret from the LinkBase class are expected to implement a get_atr method. This method is mandatory, since it is one of the most basic functionalities of pySim to display an ATR. Also the ATR is sometimes needed to distinguish between different card models. The modem_atcmd and calypso implementation completely lack the get_atr method. Apparantly it is not possible to get an ATR in those environments, so lets add a dummy method there. Related: OS#6322 Change-Id: I4fc020ca45658af78e495a5c1b985213f83cbb50
192 lines
7.0 KiB
Python
192 lines
7.0 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2020 Vadim Yanitskiy <axilirator@gmail.com>
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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import logging as log
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import time
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import re
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import argparse
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from typing import Optional
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import serial
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from osmocom.utils import Hexstr
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from pySim.utils import ResTuple
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from pySim.transport import LinkBaseTpdu
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from pySim.exceptions import ReaderError, ProtocolError
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# HACK: if somebody needs to debug this thing
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# log.root.setLevel(log.DEBUG)
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class ModemATCommandLink(LinkBaseTpdu):
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"""Transport Link for 3GPP TS 27.007 compliant modems."""
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name = "modem for Generic SIM Access (3GPP TS 27.007)"
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def __init__(self, opts: argparse.Namespace = argparse.Namespace(modem_dev='/dev/ttyUSB0',
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modem_baud=115200), **kwargs):
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device = opts.modem_dev
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baudrate = opts.modem_baud
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super().__init__(**kwargs)
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self._sl = serial.Serial(device, baudrate, timeout=5)
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self._echo = False # this will be auto-detected by _check_echo()
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self._device = device
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self._atr = None
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# Check the AT interface
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self._check_echo()
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# Trigger initial reset
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self.reset_card()
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def __del__(self):
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if hasattr(self, '_sl'):
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self._sl.close()
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def send_at_cmd(self, cmd, timeout=0.2, patience=0.002):
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# Convert from string to bytes, if needed
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bcmd = cmd if isinstance(cmd, bytes) else cmd.encode()
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bcmd += b'\r'
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# Clean input buffer from previous/unexpected data
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self._sl.reset_input_buffer()
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# Send command to the modem
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log.debug('Sending AT command: %s', cmd)
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try:
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wlen = self._sl.write(bcmd)
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assert wlen == len(bcmd)
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except Exception as exc:
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raise ReaderError('Failed to send AT command: %s' % cmd) from exc
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rsp = b''
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its = 1
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t_start = time.time()
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while True:
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rsp = rsp + self._sl.read(self._sl.in_waiting)
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lines = rsp.split(b'\r\n')
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if len(lines) >= 2:
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res = lines[-2]
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if res == b'OK':
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log.debug('Command finished with result: %s', res)
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break
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if res == b'ERROR' or res.startswith(b'+CME ERROR:'):
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log.error('Command failed with result: %s', res)
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break
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if time.time() - t_start >= timeout:
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log.info('Command finished with timeout >= %ss', timeout)
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break
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time.sleep(patience)
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its += 1
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log.debug('Command took %0.6fs (%d cycles a %fs)', time.time() - t_start, its, patience)
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if self._echo:
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# Skip echo chars
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rsp = rsp[wlen:]
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rsp = rsp.strip()
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rsp = rsp.split(b'\r\n\r\n')
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log.debug('Got response from modem: %s', rsp)
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return rsp
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def _check_echo(self):
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"""Verify the correct response to 'AT' command
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and detect if inputs are echoed by the device
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Although echo of inputs can be enabled/disabled via
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ATE1/ATE0, respectively, we rather detect the current
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configuration of the modem without any change.
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"""
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# Next command shall not strip the echo from the response
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self._echo = False
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result = self.send_at_cmd('AT')
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# Verify the response
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if len(result) > 0:
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if result[-1] == b'OK':
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self._echo = False
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return
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if result[-1] == b'AT\r\r\nOK':
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self._echo = True
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return
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raise ReaderError('Interface \'%s\' does not respond to \'AT\' command' % self._device)
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def _reset_card(self):
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# Reset the modem, just to be sure
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if self.send_at_cmd('ATZ') != [b'OK']:
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raise ReaderError('Failed to reset the modem')
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# Make sure that generic SIM access is supported
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if self.send_at_cmd('AT+CSIM=?') != [b'OK']:
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raise ReaderError('The modem does not seem to support SIM access')
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log.info('Modem at \'%s\' is ready!', self._device)
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def connect(self):
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pass # Nothing to do really ...
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def get_atr(self) -> Hexstr:
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return "3b00" # Dummy ATR
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def disconnect(self):
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pass # Nothing to do really ...
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def wait_for_card(self, timeout: Optional[int] = None, newcardonly: bool = False):
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pass # Nothing to do really ...
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def send_tpdu(self, tpdu: Hexstr) -> ResTuple:
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# Make sure pdu has upper case hex digits [A-F]
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tpdu = tpdu.upper()
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# Prepare the command as described in 8.17
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cmd = 'AT+CSIM=%d,\"%s\"' % (len(tpdu), tpdu)
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log.debug('Sending command: %s', cmd)
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# Send AT+CSIM command to the modem
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rsp = self.send_at_cmd(cmd)
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if rsp[-1].startswith(b'+CME ERROR:'):
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raise ProtocolError('AT+CSIM failed with: %s' % str(rsp))
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if len(rsp) != 2 or rsp[-1] != b'OK':
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raise ReaderError('APDU transfer failed: %s' % str(rsp))
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rsp = rsp[0] # Get rid of b'OK'
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# Make sure that the response has format: b'+CSIM: %d,\"%s\"'
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try:
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result = re.match(b'\+CSIM: (\d+),\"([0-9A-F]+)\"', rsp)
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(_rsp_tpdu_len, rsp_tpdu) = result.groups()
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except Exception as exc:
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raise ReaderError('Failed to parse response from modem: %s' % rsp) from exc
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# TODO: make sure we have at least SW
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data = rsp_tpdu[:-4].decode().lower()
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sw = rsp_tpdu[-4:].decode().lower()
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log.debug('Command response: %s, %s', data, sw)
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return data, sw
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def __str__(self) -> str:
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return "modem:%s" % self._device
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@staticmethod
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def argparse_add_reader_args(arg_parser: argparse.ArgumentParser):
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modem_group = arg_parser.add_argument_group('AT Command Modem Reader', """Talk to a SIM Card inside a
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mobile phone or cellular modem which is attached to this computer and offers an AT command interface including
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the AT+CSIM interface for Generic SIM access as specified in 3GPP TS 27.007.""")
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modem_group.add_argument('--modem-device', dest='modem_dev', metavar='DEV', default=None,
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help='Serial port of modem for Generic SIM Access (3GPP TS 27.007)')
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modem_group.add_argument('--modem-baud', type=int, metavar='BAUD', default=115200,
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help='Baud rate used for modem port')
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