feat(xml): Add and detect XML rule elements

update-firewall-source.py

@@ -233,10 +233,37 @@ def validate_config_sections(
                     config_obj.remove_option(this_section, key)
 
 
-def gen_fw_rule_xml(ip_addresses: dict[str, list]) -> lxml.builder.ElementMaker:
-    len_ipv4_addresses = len(ip_addresses["ipv4"])
-    len_ipv6_addresses = len(ip_addresses["ipv6"])
-    data = lxml.builder.ElementMaker()
+def has_child_elem(elem_name: str, attr_value: str) -> bool:
+    global arg_fw_rule_data
+    attr_name = "ipv"
+
+    for elem in arg_fw_rule_data.findall(elem_name):
+        if elem.attrib[attr_name] == attr_value:
+            log.debug(f"""XML has element '<{elem_name} {attr_name}="{attr_value}" .../>'""")
+            return True
+    log.debug(f"""No XML element '<{elem_name} {attr_name}="{attr_value}" .../>'""")
+    return False
+
+
+def add_chain_elem(elem_name: str, addr_family: str) -> bool:
+    global arg_fw_rule_data
+
+    log.debug(f"Adding new ...")
+    for chain in ["FILTERS", "DOCKER-USER"]:
+        try:
+            lxml.etree.SubElement(arg_fw_rule_data, elem_name,
+                                  ipv=f"{addr_family}",
+                                  table="filter",
+                                  chain=chain)
+        except lxml.etree.LxmlError as le:
+            log.error(f"""Failed to add XML '<{elem_name} ipv=f"{addr_family}" .../>'\n"""
+                      f"Verbatim exception was:\n"
+                      f"f{le}\n"
+                      f"Exiting 8 ...")
+            sys.exit(8)
+
+    return True
+
 
     direct_tag = data.direct
     chain_tag = data.chain