laforge has submitted this change. ( https://gerrit.osmocom.org/c/pysim/+/42475?usp=email )
Change subject: pysim/pcsc: do not use getProtocol for protocol selection ...................................................................... pysim/pcsc: do not use getProtocol for protocol selection The documentation of the getProtocol provided by pyscard says: "Return bit mask for the protocol of connection, or None if no protocol set. The return value is a bit mask of CardConnection.T0_protocol, CardConnection.T1_protocol, CardConnection.RAW_protocol, CardConnection.T15_protocol" This suggests that the purpose of getProtocol is not to determine which protocols are supported. Its purpose is to determine which protocol is currently selected (either through auto selection or through the explicit selection made by the API user). This means we are using getProtocol wrong. So far this was no problem, since the auto-selected protocol should be a supported protocol anyway. However, the automatic protocol selection may not always return a correct result (see bug report from THD-siegfried [1]). Let's not trust the automatic protocol selection. Instead let's parse the ATR and make the decision based on the TD1/TD2 bytes). [1] https://osmocom.org/issues/6952 Related: OS#6952 Change-Id: Ib119948aa68c430e42ac84daec8b9bd542db7963 --- M pySim/transport/pcsc.py 1 file changed, 11 insertions(+), 7 deletions(-) Approvals: Jenkins Builder: Verified fixeria: Looks good to me, approved jolly: Looks good to me, but someone else must approve diff --git a/pySim/transport/pcsc.py b/pySim/transport/pcsc.py index c92a3ba..21d3ce4 100644 --- a/pySim/transport/pcsc.py +++ b/pySim/transport/pcsc.py @@ -26,6 +26,7 @@ from smartcard.Exceptions import NoCardException, CardRequestTimeoutException, CardConnectionException from smartcard.System import readers from smartcard.ExclusiveConnectCardConnection import ExclusiveConnectCardConnection +from smartcard.ATR import ATR from osmocom.utils import h2i, i2h, Hexstr @@ -84,18 +85,21 @@ self.disconnect() # Make card connection and select a suitable communication protocol + # (Even though pyscard provides an automatic protocol selection, we will make an independent decision + # based on the ATR. There are two reasons for that: + # 1) In case a card supports T=0 and T=1, we perfer to use T=0. + # 2) The automatic protocol selection may be unreliabe on some platforms + # see also: https://osmocom.org/issues/6952) self._con.connect() - supported_protocols = self._con.getProtocol(); - self.disconnect() - if (supported_protocols & CardConnection.T0_protocol): - protocol = CardConnection.T0_protocol + atr = ATR(self._con.getATR()) + if atr.isT0Supported(): + self._con.setProtocol(CardConnection.T0_protocol) self.set_tpdu_format(0) - elif (supported_protocols & CardConnection.T1_protocol): - protocol = CardConnection.T1_protocol + elif atr.isT1Supported(): + self._con.setProtocol(CardConnection.T1_protocol) self.set_tpdu_format(1) else: raise ReaderError('Unsupported card protocol') - self._con.connect(protocol) except CardConnectionException as exc: raise ProtocolError() from exc except NoCardException as exc: -- To view, visit https://gerrit.osmocom.org/c/pysim/+/42475?usp=email To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings?usp=email Gerrit-MessageType: merged Gerrit-Project: pysim Gerrit-Branch: master Gerrit-Change-Id: Ib119948aa68c430e42ac84daec8b9bd542db7963 Gerrit-Change-Number: 42475 Gerrit-PatchSet: 4 Gerrit-Owner: dexter <[email protected]> Gerrit-Reviewer: Jenkins Builder Gerrit-Reviewer: fixeria <[email protected]> Gerrit-Reviewer: jolly <[email protected]> Gerrit-Reviewer: laforge <[email protected]>
