Added support for smart card events

platypush/backend/scard/__init__.py

@@ -0,0 +1,76 @@
+import logging
+import json
+
+from smartcard.CardType import AnyCardType, ATRCardType
+from smartcard.CardRequest import CardRequest
+from smartcard.util import toHexString
+
+from platypush.backend import Backend
+from platypush.message.event.scard import SmartCardDetectedEvent
+
+
+class ScardBackend(Backend):
+    """
+    Generic backend to read smart cards and trigger SmartCardDetectedEvent
+    messages with the card ATR whenever a card is detected. It requires
+    pyscard https://pypi.org/project/pyscard/
+
+    Extend this backend to implement more advanced communication with
+    custom smart cards.
+    """
+
+    def __init__(self, atr=None, *args, **kwargs):
+        """
+        Params:
+            atr -- If set, the backend will trigger events only for card(s)
+                with the specified ATR(s). It can be either an ATR string
+                (space-separated hex octects) or a list of ATR strings.
+                Default: none (any card will be detected)
+        """
+        super().__init__(*args, **kwargs)
+        self.ATRs = []
+
+        if atr:
+            if isinstance(atr, str):
+                self.ATRs = [atr]
+            elif isinstance(atr, list):
+                self.ATRs = atr
+            else:
+                raise RuntimeError("Unsupported ATR: \"{}\" - type: {}, " +
+                                   "supported types: string, list".format(
+                                       atr, type(atr)))
+
+            self.cardtype = ATRCardType( *[toBytes(atr) for atr in self.ATRs] )
+        else:
+            self.cardtype = AnyCardType()
+
+
+    def run(self):
+        super().run()
+
+        logging.info('Initialized smart card reader backend - ATR filter: {}'.
+                     format(self.ATRs))
+
+        prev_atr = None
+        while not self.should_stop():
+            try:
+                cardrequest = CardRequest(timeout=None, cardType=self.cardtype)
+                cardservice = cardrequest.waitforcard()
+                cardservice.connection.connect()
+
+                reader = cardservice.connection.getReader()
+                atr = toHexString(cardservice.connection.getATR())
+
+                if atr != prev_atr:
+                    logging.info('Smart card detected on reader {}, ATR: {}'.
+                                format(reader, atr))
+
+                    self.bus.post(SmartCardDetectedEvent(atr=atr, reader=reader))
+                    prev_atr = atr
+            except Exception as e:
+                logging.exception(e)
+                prev_atr = None
+
+
+# vim:sw=4:ts=4:et:
+

platypush/message/event/scard.py

@@ -0,0 +1,10 @@
+from platypush.message.event import Event
+
+
+class SmartCardDetectedEvent(Event):
+    def __init__(self, atr, reader=None, *args, **kwargs):
+        super().__init__(atr=atr, reader=reader, *args, **kwargs)
+
+
+# vim:sw=4:ts=4:et:
+