fix issue in random_mac filter with short prefixes (#53928)

changelogs/fragments/random_mac-random-int-fix.yaml

@@ -0,0 +1,2 @@
+bugfixes:
+  - random_mac - generate a proper MAC address when the provided vendor prefix is two or four characters (https://github.com/ansible/ansible/issues/50838)

lib/ansible/plugins/filter/core.py

@@ -36,7 +36,7 @@ import yaml
 
 import datetime
 from functools import partial
-from random import Random, SystemRandom, shuffle, random
+from random import Random, SystemRandom, shuffle, randint
 
 from jinja2.filters import environmentfilter, do_groupby as _do_groupby
 
@@ -555,8 +555,8 @@ def random_mac(value):
     if len(err):
         raise AnsibleFilterError('Invalid value (%s) for random_mac: %s' % (value, err))
 
-    # Generate random float and make it int
+    # Generate random int between x1000000000 and xFFFFFFFFFF
-    v = int(random() * 10.0**10)
+    v = randint(68719476736, 1099511627775)
     # Select first n chars to complement input prefix
     remain = 2 * (6 - len(mac_items))
     rnd = ('%x' % v)[:remain]

test/integration/targets/filters/tasks/main.yml

@@ -235,7 +235,11 @@
 - name:  Verify random_mac filter
   assert:
     that:
+            - "'00' | random_mac is match('^00:[a-f0-9][a-f0-9]:[a-f0-9][a-f0-9]:[a-f0-9][a-f0-9]:[a-f0-9][a-f0-9]:[a-f0-9][a-f0-9]$')"
+            - "'00:00' | random_mac is match('^00:00:[a-f0-9][a-f0-9]:[a-f0-9][a-f0-9]:[a-f0-9][a-f0-9]:[a-f0-9][a-f0-9]$')"  
             - "'00:00:00' | random_mac is match('^00:00:00:[a-f0-9][a-f0-9]:[a-f0-9][a-f0-9]:[a-f0-9][a-f0-9]$')"
+            - "'00:00:00:00' | random_mac is match('^00:00:00:[a-f0-9][a-f0-9]:[a-f0-9][a-f0-9]:[a-f0-9][a-f0-9]$')"
+            - "'00:00:00:00:00' | random_mac is match('^00:00:00:00:00:[a-f0-9][a-f0-9]$')"  
             - "'00:00:00' | random_mac != '00:00:00' | random_mac"
 
 - name: Verify that union can be chained