json_schema: chain resolve error and cover mapped/CGNAT in retrieve guard

Signed-off-by: Uwez Khan <uwezkhan053@gmail.com>

Author: uwezkhan

src/confluent_kafka/schema_registry/common/json_schema.py

@@ -78,7 +78,7 @@ def _guard_external_uri(uri: str):
     try:
         infos = socket.getaddrinfo(host, parts.port or (443 if parts.scheme == 'https' else 80))
     except socket.gaierror as ex:
-        raise ValueError("Could not resolve schema URI host {}: {}".format(host, ex))
+        raise ValueError("Could not resolve schema URI host {}: {}".format(host, ex)) from ex
     for info in infos:
         if _is_blocked_ip(ipaddress.ip_address(info[4][0])):
             raise ValueError("Refusing to retrieve schema from non-public address: {}".format(uri))

tests/schema_registry/test_json_schema_retrieve.py

@@ -30,6 +30,8 @@
     "http://127.0.0.1:8080/internal",
     "http://10.0.0.5/schema",
     "http://[::1]/schema",
+    "http://[::ffff:127.0.0.1]/schema",
+    "http://100.64.0.1/schema",
     "file:///etc/passwd",
     "gopher://127.0.0.1/x",
 ])