Add generic response chaining capability

3 files changed, 24 insertions, 2 deletions

diff --git a/cards/generic_card.py b/cards/generic_card.py
index 64d4bcb..37e3a0a 100644
--- a/cards/generic_card.py
+++ b/cards/generic_card.py
@@ -147,10 +147,16 @@ class Card:
     def _send_with_retry(self, apdu):
         result = self._real_send(apdu)
         
-        if self.check_sw(result.sw, self.PURPOSE_GET_RESPONSE):
+        while self.check_sw(result.sw, self.PURPOSE_GET_RESPONSE):
             ## Need to call GetResponse
             gr_apdu = self.COMMAND_GET_RESPONSE
-            result = self._real_send(gr_apdu)
+            tmp = self._real_send(gr_apdu)
+            
+            if not callable(result.append):
+                result = tmp
+                break
+            else:
+                result = result.append(tmp)
         
         return result
     
diff --git a/tests/utilstest.py b/tests/utilstest.py
index 65b74b6..42d34f4 100644
--- a/tests/utilstest.py
+++ b/tests/utilstest.py
@@ -36,3 +36,12 @@ class APDUCase1Tests(unittest.TestCase):
         
         self.assertEqual(self.a4.render(), a4_2.render())
 
+class APDUChainTests(unittest.TestCase):
+    
+    def testChain(self):
+        a = utils.R_APDU("abcd\x61\x04")
+        b = utils.R_APDU("efgh\x90\x00")
+        
+        c = a.append(b)
+        
+        self.assertEqual("abcdefgh\x90\x00", c.render())
diff --git a/utils.py b/utils.py
index e68007f..00533dc 100644
--- a/utils.py
+++ b/utils.py
@@ -224,6 +224,10 @@ class Transmission_Frame(object):
             parts.append("data=%r" % self.data)
         
         return "%s(%s)" % (self.__class__.__name__, ", ".join(parts))
+    
+    # Stub for implementation in subclasses
+    # Semantics should be: c=a.append(b) <=> c.data == a.data + b.data and c.status == b.status
+    append = None
 
 class Command_Frame(Transmission_Frame):
     pass
@@ -472,6 +476,9 @@ class R_APDU(Response_Frame,APDU):
     def render(self):
         "Return this APDU as a binary string"
         return self.data + self.sw
+    
+    def append(self, other):
+        return R_APDU(self.data + other.data + other.sw)
 
 APDU.COMMAND_CLASS = C_APDU
 APDU.RESPONSE_CLASS = R_APDU