Fix installer CA port check for port 8080

The installer now checks that port 8080 is available and not in use by
any other application.

The port checker has been rewritten to use bind() rather than just
checking if a server responds on localhost. It's much more reliable and
detects more problems.

Original patch by m3gat0nn4ge.

Co-authored-by: Mega Tonnage <m3gat0nn4ge@gmail.com>
Fixes: https://pagure.io/freeipa/issue/7415
Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>

ipaserver/install/cainstance.py

@@ -105,13 +105,14 @@ class ExternalCAType(enum.Enum):
     MS_CS = 'ms-cs'
 
 
-def check_port():
-    """
-    Check that dogtag port (8443) is available.
+def check_ports():
+    """Check that dogtag ports (8080, 8443) are available.
 
-    Returns True when the port is free, False if it's taken.
+    Returns True when ports are free, False if they are taken.
     """
-    return not ipautil.host_port_open(None, 8443)
+    return all([ipautil.check_port_bindable(8443),
+                ipautil.check_port_bindable(8080)])
+
 
 def get_preop_pin(instance_root, instance_name):
     # Only used for Dogtag 9