Deal with case insensitivy in cloudflare_dns module (#44366)

Cloudflare's DNS API deals with the case insensitivy of DNS names and
IPv6 addresses by forcing them into lower case. To properly be able to
detect changes the Ansible module needs to behave accordingly.

To what extent the API expects sent DNS names to be lower case varies
between record types. Yet, since sending lower case always works, and
since we always get lower case back, it feels cleanest to use lower
case for all DNS names.

lib/ansible/modules/net_tools/cloudflare_dns.py

@@ -322,6 +322,12 @@ from ansible.module_utils._text import to_native, to_text
 from ansible.module_utils.urls import fetch_url
 
 
+def lowercase_string(param):
+    if not isinstance(param, str):
+        return param
+    return param.lower()
+
+
 class CloudflareAPI(object):
 
     cf_api_endpoint = 'https://api.cloudflare.com/client/v4'
@@ -337,11 +343,11 @@ class CloudflareAPI(object):
         self.key_tag = module.params['key_tag']
         self.port = module.params['port']
         self.priority = module.params['priority']
-        self.proto = module.params['proto']
+        self.proto = lowercase_string(module.params['proto'])
         self.proxied = module.params['proxied']
         self.selector = module.params['selector']
-        self.record = module.params['record']
-        self.service = module.params['service']
+        self.record = lowercase_string(module.params['record'])
+        self.service = lowercase_string(module.params['service'])
         self.is_solo = module.params['solo']
         self.state = module.params['state']
         self.timeout = module.params['timeout']
@@ -349,13 +355,16 @@ class CloudflareAPI(object):
         self.type = module.params['type']
         self.value = module.params['value']
         self.weight = module.params['weight']
-        self.zone = module.params['zone']
+        self.zone = lowercase_string(module.params['zone'])
 
         if self.record == '@':
             self.record = self.zone
 
         if (self.type in ['CNAME', 'NS', 'MX', 'SRV']) and (self.value is not None):
-            self.value = self.value.rstrip('.')
+            self.value = self.value.rstrip('.').lower()
+
+        if (self.type == 'AAAA') and (self.value is not None):
+            self.value = self.value.lower()
 
         if (self.type == 'SRV'):
             if (self.proto is not None) and (not self.proto.startswith('_')):