Allow assigning "0" to port

Function for port validation doesn't validate "0" as a proper port
number, althought IANA RFC 6335 [1] describes as valid 0-65535.
Add missing "0" to function.

[1] https://tools.ietf.org/html/rfc6335#section-8.1.2

Change-Id: I088add52cf454e5df503ecb5d6551724fb5ddaf4
Closes-Bug: #1590485

oslo_utils/netutils.py

@@ -222,12 +222,12 @@ def _is_int_in_range(value, start, end):
 def is_valid_port(port):
     """Verify that port represents a valid port number.
 
-    Port can be valid integer having a value of 1 up to and
+    Port can be valid integer having a value of 0 up to and
     including 65535.
 
     .. versionadded:: 1.1.1
     """
-    return _is_int_in_range(port, 1, 65535)
+    return _is_int_in_range(port, 0, 65535)
 
 
 def is_valid_icmp_type(type):

oslo_utils/tests/test_netutils.py

@@ -193,13 +193,13 @@ class NetworkUtilsTest(test_base.BaseTestCase):
         self.assertFalse(netutils.is_valid_cidr(10))
 
     def test_valid_port(self):
-        valid_inputs = [1, '1', 2, '3', '5', 8, 13, 21,
+        valid_inputs = [0, '0', 1, '1', 2, '3', '5', 8, 13, 21,
                         '80', '3246', '65535']
         for input_str in valid_inputs:
             self.assertTrue(netutils.is_valid_port(input_str))
 
     def test_valid_port_fail(self):
-        invalid_inputs = ['-32768', '0', 0, '65536', 528491, '528491',
+        invalid_inputs = ['-32768', '65536', 528491, '528491',
                           '528.491', 'thirty-seven', None]
         for input_str in invalid_inputs:
             self.assertFalse(netutils.is_valid_port(input_str))

releasenotes/notes/bump-up-port-range-f774a16336158339.yaml

@@ -0,0 +1,3 @@
+---
+fixes:
+  - Expanded range of allowed ports by adding 0 to valid number.