Py3: remove __getslice__ method

__getslice__ is deprecated in py2 and it is not used in py3 at all.
Instead of this __getitem__ with slice() index should be used.

Please note that WireData class must still use __getslice__, because it
inherites from 'binary_type' class that has implemented __getslice__
thus this method has to be overriden in WireData class.

1 files changed, 39 insertions, 20 deletions

diff --git a/dns/wiredata.py b/dns/wiredata.py
index b381f7b..ccef595 100644
--- a/dns/wiredata.py
+++ b/dns/wiredata.py
@@ -15,6 +15,7 @@
 
 """DNS Wire Data Helper"""
 
+import sys
 
 import dns.exception
 from ._compat import binary_type, string_types
@@ -26,12 +27,16 @@ from ._compat import binary_type, string_types
 # out what constant Python will use.
 
 
-class _SliceUnspecifiedBound(str):
+class _SliceUnspecifiedBound(binary_type):
 
-    def __getslice__(self, i, j):
-        return j
+    def __getitem__(self, key):
+        return key.stop
+
+    if sys.version_info < (3,):
+        def __getslice__(self, i, j):  # pylint: disable=getslice-method
+            return self.__getitem__(slice(i, j))
 
-_unspecified_bound = _SliceUnspecifiedBound('')[1:]
+_unspecified_bound = _SliceUnspecifiedBound()[1:]
 
 
 class WireData(binary_type):
@@ -40,26 +45,40 @@ class WireData(binary_type):
     def __getitem__(self, key):
         try:
             if isinstance(key, slice):
-                return WireData(super(WireData, self).__getitem__(key))
+                # make sure we are not going outside of valid ranges,
+                # do stricter control of boundaries than python does
+                # by default
+                start = key.start
+                stop = key.stop
+
+                if sys.version_info < (3,):
+                    if stop == _unspecified_bound:
+                        # handle the case where the right bound is unspecified
+                        stop = len(self)
+
+                    if start < 0 or stop < 0:
+                        raise dns.exception.FormError
+                    # If it's not an empty slice, access left and right bounds
+                    # to make sure they're valid
+                    if start != stop:
+                        super(WireData, self).__getitem__(start)
+                        super(WireData, self).__getitem__(stop - 1)
+                else:
+                    for index in (start, stop):
+                        if index is None:
+                            continue
+                        elif abs(index) > len(self):
+                            raise dns.exception.FormError
+
+                return WireData(super(WireData, self).__getitem__(
+                    slice(start, stop)))
             return bytearray(self.unwrap())[key]
         except IndexError:
             raise dns.exception.FormError
 
-    def __getslice__(self, i, j):
-        try:
-            if j == _unspecified_bound:
-                # handle the case where the right bound is unspecified
-                j = len(self)
-            if i < 0 or j < 0:
-                raise dns.exception.FormError
-            # If it's not an empty slice, access left and right bounds
-            # to make sure they're valid
-            if i != j:
-                super(WireData, self).__getitem__(i)
-                super(WireData, self).__getitem__(j - 1)
-            return WireData(super(WireData, self).__getslice__(i, j))
-        except IndexError:
-            raise dns.exception.FormError
+    if sys.version_info < (3,):
+        def __getslice__(self, i, j):  # pylint: disable=getslice-method
+            return self.__getitem__(slice(i, j))
 
     def __iter__(self):
         i = 0