Reimplement is_valid_ipv4().

This patch reimplements the is_valid_ipv4() function is nova.utils.
Instead of open-coding the validity check, just make use of the netaddr
module, which is already used elsewhere in nova.utils.

Also add a unit test for this code.

Part of indigoprint bored-on-an-airplane.

Change-Id: Ia89cbbd94a0ac4631d794d658b53c244237e1ca2

nova/tests/test_utils.py

@@ -476,6 +476,11 @@ class GenericUtilsTestCase(test.TestCase):
         self.assertFalse(utils.is_valid_boolstr('maybe'))
         self.assertFalse(utils.is_valid_boolstr('only on tuesdays'))
 
+    def test_is_valid_ipv4(self):
+        self.assertTrue(utils.is_valid_ipv4('127.0.0.1'))
+        self.assertFalse(utils.is_valid_ipv4('::1'))
+        self.assertFalse(utils.is_valid_ipv4('bacon'))
+
 
 class MonkeyPatchTestCase(test.TestCase):
     """Unit test for utils.monkey_patch()."""

nova/utils.py

@@ -881,19 +881,12 @@ def is_valid_boolstr(val):
 
 
 def is_valid_ipv4(address):
-    """valid the address strictly as per format xxx.xxx.xxx.xxx.
-    where xxx is a value between 0 and 255.
-    """
-    parts = address.split(".")
-    if len(parts) != 4:
+    """Verify that address represents a valid IPv4 address."""
+    try:
+        addr = netaddr.IPAddress(address)
+        return addr.version == 4
+    except Exception:
         return False
-    for item in parts:
-        try:
-            if not 0 <= int(item) <= 255:
-                return False
-        except ValueError:
-            return False
-    return True
 
 
 def is_valid_cidr(address):