* some more fixes to OID codecs

* explicit limit on ObjectIdentifier arc value size removed
* some more tests in OID encoding problem areas added

2 files changed, 43 insertions, 45 deletions

diff --git a/pyasn1/codec/ber/decoder.py b/pyasn1/codec/ber/decoder.py
index 1530a54..d0c9814 100644
--- a/pyasn1/codec/ber/decoder.py
+++ b/pyasn1/codec/ber/decoder.py
@@ -216,30 +216,14 @@ class ObjectIdentifierDecoder(AbstractSimpleDecoder):
         if not head:
             raise error.PyAsn1Error('Empty substrate')
 
-        # Decode the first octet
-        index = 1
-        subId = oct2int(head[0])
-        if 0 <= subId <= 39:
-            oid = 0, subId
-        elif 40 <= subId <= 79:
-            oid = 1, subId - 40
-        elif subId >= 80:
-            oid = 2,
-            index = 0
-        else:
-            raise error.PyAsn1Error('Malformed first OID octet: %s' % subId)
-
+        oid = ()
+        index = 0
         substrateLen = len(head)
         while index < substrateLen:
             subId = oct2int(head[index])
-            if index == 0:
-                subId -= 80
-            index = index + 1
-            if subId == 128:
-                # ASN.1 spec forbids leading zeros (0x80) in sub-ID OID
-                # encoding, tolerating it opens a vulnerability.
-                # See http://www.cosic.esat.kuleuven.be/publications/article-1432.pdf page 7
-                raise error.PyAsn1Error('Invalid leading 0x80 in sub-OID')
+            index += 1
+            if subId < 128:
+                oid = oid + (subId,)
             elif subId > 128:
                 # Construct subid from a number of octets
                 nextSubId = subId
@@ -249,11 +233,27 @@ class ObjectIdentifierDecoder(AbstractSimpleDecoder):
                     if index >= substrateLen:
                         raise error.SubstrateUnderrunError(
                             'Short substrate for sub-OID past %s' % (oid,)
-                            )
+                        )
                     nextSubId = oct2int(head[index])
-                    index = index + 1
-                subId = (subId << 7) + nextSubId
-            oid = oid + (subId,)
+                    index += 1
+                oid = oid + ((subId << 7) + nextSubId,)
+            elif subId == 128:
+                # ASN.1 spec forbids leading zeros (0x80) in OID
+                # encoding, tolerating it opens a vulnerability. See
+                # http://www.cosic.esat.kuleuven.be/publications/article-1432.pdf
+                # page 7
+                raise error.PyAsn1Error('Invalid octet 0x80 in OID encoding')
+       
+        # Decode two leading arcs
+        if 0 <= oid[0] <= 39:
+            oid = (0,) + oid
+        elif 40 <= oid[0] <= 79:
+            oid = (1, oid[0]-40) + oid[1:]
+        elif oid[0] >= 80:
+            oid = (2, oid[0]-80) + oid[1:]
+        else:
+            raise error.PyAsn1Error('Malformed first OID octet: %s' % head[0])
+
         return self._createComponent(asn1Spec, tagSet, oid), tail
 
 class RealDecoder(AbstractSimpleDecoder):
diff --git a/pyasn1/codec/ber/encoder.py b/pyasn1/codec/ber/encoder.py
index a52f9da..b19f240 100644
--- a/pyasn1/codec/ber/encoder.py
+++ b/pyasn1/codec/ber/encoder.py
@@ -156,48 +156,46 @@ class ObjectIdentifierEncoder(AbstractItemEncoder):
     precomputedValues = {
         (1, 3, 6, 1, 2): (43, 6, 1, 2),        
         (1, 3, 6, 1, 4): (43, 6, 1, 4)
-        }
+    }
     def encodeValue(self, encodeFun, value, defMode, maxChunkSize):    
         oid = value.asTuple()
         if oid[:5] in self.precomputedValues:
+            oid = oid[5:]
             octets = self.precomputedValues[oid[:5]]
-            index = 5
         else:
             if len(oid) < 2:
                 raise error.PyAsn1Error('Short OID %s' % (value,))
 
-            index = 2
+            octets = ()
 
             # Build the first twos
             if oid[0] == 0 and 0 <= oid[1] <= 39:
-                octets = (oid[1],)
+                oid = (oid[1],) + oid[2:]
             elif oid[0] == 1 and 0 <= oid[1] <= 39:
-                octets = (oid[1] + 40,)
+                oid = (oid[1] + 40,) + oid[2:]
             elif oid[0] == 2:
-                octets = ()
                 oid = (oid[1] + 80,) + oid[2:]
-                index = 0
             else:
                 raise error.PyAsn1Error(
-                    'Initial sub-ID overflow %s in OID %s' % (oid[:2], value)
+                    'Impossible initial arcs %s at %s' % (oid[:2], value)
                     )
 
-        # Cycle through subids
-        for subid in oid[index:]:
-            if subid > -1 and subid < 128:
+        # Cycle through subIds
+        for subId in oid:
+            if subId > -1 and subId < 128:
                 # Optimize for the common case
-                octets = octets + (subid & 0x7f,)
-            elif subid < 0:
+                octets = octets + (subId & 0x7f,)
+            elif subId < 0:
                 raise error.PyAsn1Error(
-                    'SubId overflow %s in %s' % (subid, value)
-                    )
+                    'Negative OID arc %s at %s' % (subId, value)
+                )
             else:
                 # Pack large Sub-Object IDs
-                res = (subid & 0x7f,)
-                subid = subid >> 7
-                while subid > 0:
-                    res = (0x80 | (subid & 0x7f),) + res
-                    subid = subid >> 7 
+                res = (subId & 0x7f,)
+                subId = subId >> 7
+                while subId > 0:
+                    res = (0x80 | (subId & 0x7f),) + res
+                    subId = subId >> 7 
                 # Add packed Sub-Object ID to resulted Object ID
                 octets += res