Dynamic DNS service for mcu-app.
Assumes a mod_wsgi environment where the current working directory is a private home directory, separate from the httpd document root.
The user database is PostgreSQL, with a separate password per hostname.
Requires a DNS service that uses zone files in a Git repositories (with automatic serial handling on the server side). A separate zone is best for dynamic DNS.
Requests are CBOR-encoded (RFC 8949) POST data of the form:
{"hostname": "...", "password": "...", "ip4": "...", "ip6": "..."}
Responses are CBOR-encoded, success:
[True]
or failure:
[False, "Error message"]
The client is expected to remember the previous IP addresses it used and not make repeated requests after it is successful.