Allow repeated tags in Data Object Lists

This is apparently allowed and used by some applications

fixes #22

Author: russss

emv/protocol/structures.py

@@ -129,7 +129,7 @@ def __repr__(self):
         return ret
 
 
-class DOL(OrderedDict):
+class DOL(list):
     """Data Object List.
     This is sent by the card to the terminal to define a structure for
     future transactions, consisting of an ordered list of data elements and lengths.
@@ -148,12 +148,12 @@ def unmarshal(cls, data):
             i += tag_len
             length = data[i]
             i += 1
-            dol[Tag(tag)] = length
+            dol.append((Tag(tag), length))
         return dol
 
     def size(self):
         """Total size of the resulting structure in bytes."""
-        return sum(self.values())
+        return sum([val[1] for val in self])
 
     def unserialise(self, data):
         """Parse an input stream of bytes and return a TLV object."""
@@ -165,18 +165,24 @@ def unserialise(self, data):
 
         tlv = TLV()
         i = 0
-        for tag, length in self.items():
+        for tag, length in self:
             tlv[tag] = data[i : i + length]
             i += length
 
         return tlv
 
+    def __contains__(self, val):
+        for v in self:
+            if v[0] == val:
+                return True
+        return False
+
     def serialise(self, data):
         """Given a dictionary of tag -> value, write this data out
         according to the DOL. Missing data will be null.
         """
         output = []
-        for tag, length in self.items():
+        for tag, length in self:
             value = data.get(tag, [0x0] * length)
             if len(value) < length:
                 # If the length is shorter than required, left-pad it.

emv/protocol/test/test_structures.py

@@ -92,11 +92,15 @@ def test_invalid_tlv():
 def test_dol():
     dol = DOL.unmarshal(dol_data)
     assert 0x9A in dol
-    assert dol[0x9A] == 3
     assert (0x9F, 0x37) in dol
-    assert dol[(0x9F, 0x37)] == 4
     assert dol.size() == 29
 
+    # This DOL has a repeated 0x9A entry, for some reason. Apparently this is allowed.
+    data = unformat_bytes("9F 66 04 9F 02 06 9F 03 06 9F 1A 02 95 05 5F 2A 02 9A 03 9C 01 9F 37 04 9A 03")
+    dol = DOL.unmarshal(data)
+
+    assert len([t for t in dol if t[0] == 0x9A]) == 2
+
 
 def test_serialise():
     dol = DOL.unmarshal(dol_data)
@@ -166,4 +170,4 @@ def test_taglist():
 
 def test_cvmlist():
     data = unformat_bytes("00 00 00 00 00 00 00 00 41 03 1E 03 02 03 1F 03")
-    print(CVMList.unmarshal(data))
+    CVMList.unmarshal(data)

emv/util.py

@@ -44,7 +44,7 @@ def format_bytes(data):
 
 
 def unformat_bytes(data):
-    data = re.split(r"\s+", data)
+    data = re.split(r"(?:\s+|:)", data)
     return [int(i, 16) for i in data]