fixed crash on unknown PDU reporting

Also, TextualConvention is now a new-style class

CHANGES.txt

@@ -6,6 +6,10 @@ Revision 4.3.5, released 2017-0X-XX
   now support ignoreNonIncreasingOid option.
 - Fix to accidentally reset error-status when building confirmed class
   SNMPv1 PDU
+- Fix to possible infinite recursion in TextualConvention.prettyIn()
+- TextualConvention is now a new-style class
+- Fixed crash when attempting to report unsupported request/notification
+  PDU back to sender
 
 Revision 4.3.4, released 2017-03-01
 -----------------------------------

pysnmp/proto/rfc3412.py

@@ -361,8 +361,6 @@ class MsgAndPduDispatcher(object):
 
                 debug.logger & debug.flagDsp and debug.logger('receiveMessage: unhandled PDU type')
 
-                # XXX fails on unknown PDU
-
                 try:
                     (destTransportDomain,
                      destTransportAddress,
@@ -374,7 +372,7 @@ class MsgAndPduDispatcher(object):
                         statusInformation
                     )
 
-                except error.StatusInformation:
+                except (error.StatusInformation, error.ProtocolError):
                     debug.logger & debug.flagDsp and debug.logger(
                         'receiveMessage: report failed, statusInformation %s' % sys.exc_info()[1])
                     return restOfWholeMsg

pysnmp/smi/mibs/SNMPv2-TC.py

@@ -29,8 +29,7 @@ Counter32, Unsigned32, TimeTicks, Counter64 = mibBuilder.importSymbols(
 )
 
 
-# XXX keep this old-style class till pyasn1 types becomes new-style
-class TextualConvention:
+class TextualConvention(object):
     displayHint = ''
     status = 'current'
     description = ''
@@ -184,7 +183,7 @@ class TextualConvention:
             return outputValue
 
         for base in inspect.getmro(self.__class__):
-            if base != self.__class__ and issubclass(base, Asn1Item):
+            if not issubclass(base, TextualConvention) and issubclass(base, Asn1Item):
                 return base.prettyOut(self, value)
 
         raise SmiError('TEXTUAL-CONVENTION has no underlying SNMP base type')
@@ -200,7 +199,7 @@ class TextualConvention:
         input meaning `unicode` (Py2) or `str` (Py3).
         """
         for base in inspect.getmro(self.__class__):
-            if base != self.__class__ and issubclass(base, Asn1Item):
+            if not issubclass(base, TextualConvention) and issubclass(base, Asn1Item):
                 break
         else:
             raise SmiError('TEXTUAL-CONVENTION has no underlying SNMP base type')