bpo-36384: Remove check for leading zeroes in IPv4 addresses (GH-12577)

Stop rejecting IPv4 octets with leading zeroes as ambiguously octal.

Plenty of other tools generate decimal IPv4 octets with leading zeroes,
so keeping this check hurts interoperability.

Patch by Joel Croteau.

diff --git a/Lib/ipaddress.py b/Lib/ipaddress.py
index 15507d61dec8f960d7633bff486fcae0506d7fb9..a88cf3d0b7c5d66916a0dd05ef951756195fc9d3 100644 (file)
--- a/Lib/ipaddress.py
+++ b/Lib/ipaddress.py
@@ -1165,12 +1165,6 @@ class _BaseV4:
             raise ValueError(msg % octet_str)
         # Convert to integer (we know digits are legal)
         octet_int = int(octet_str, 10)
-        # Any octets that look like they *might* be written in octal,
-        # and which don't look exactly the same in both octal and
-        # decimal are rejected as ambiguous
-        if octet_int > 7 and octet_str[0] == '0':
-            msg = "Ambiguous (octal/decimal) value in %r not permitted"
-            raise ValueError(msg % octet_str)
         if octet_int > 255:
             raise ValueError("Octet %d (> 255) not permitted" % octet_int)
         return octet_int

diff --git a/Lib/test/test_ipaddress.py b/Lib/test/test_ipaddress.py
index 0e0753f34c490543fe522fcce54dcd9b77bd23f6..53f6f128443c523e1ea906bab5e39ca992e0b46d 100644 (file)
--- a/Lib/test/test_ipaddress.py
+++ b/Lib/test/test_ipaddress.py
@@ -92,11 +92,14 @@ class CommonTestMixin:
                 y = pickle.loads(pickle.dumps(x, proto))
                 self.assertEqual(y, x)
 
+
 class CommonTestMixin_v4(CommonTestMixin):
 
     def test_leading_zeros(self):
         self.assertInstancesEqual("000.000.000.000", "0.0.0.0")
         self.assertInstancesEqual("192.168.000.001", "192.168.0.1")
+        self.assertInstancesEqual("016.016.016.016", "16.16.16.16")
+        self.assertInstancesEqual("001.000.008.016", "1.0.8.16")
 
     def test_int(self):
         self.assertInstancesEqual(0, "0.0.0.0")
@@ -229,15 +232,6 @@ class AddressTestCase_v4(BaseTestCase, CommonTestMixin_v4):
         assertBadOctet("1.2.3.4::", "4::")
         assertBadOctet("1.a.2.3", "a")
 
-    def test_octal_decimal_ambiguity(self):
-        def assertBadOctet(addr, octet):
-            msg = "Ambiguous (octal/decimal) value in %r not permitted in %r"
-            with self.assertAddressError(re.escape(msg % (octet, addr))):
-                ipaddress.IPv4Address(addr)
-
-        assertBadOctet("016.016.016.016", "016")
-        assertBadOctet("001.000.008.016", "008")
-
     def test_octet_length(self):
         def assertBadOctet(addr, octet):
             msg = "At most 3 characters permitted in %r in %r"

diff --git a/Misc/NEWS.d/next/Library/2019-03-27-02-09-22.bpo-36385.we2F45.rst b/Misc/NEWS.d/next/Library/2019-03-27-02-09-22.bpo-36385.we2F45.rst
new file mode 100644 (file)
index 0000000..26f6dd7
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-03-27-02-09-22.bpo-36385.we2F45.rst
@@ -0,0 +1 @@
+Stop rejecting IPv4 octets for being ambiguously octal. Leading zeros are ignored, and no longer are assumed to specify octal octets. Octets are always decimal numbers. Octets must still be no more than three digits, including leading zeroes.