mod_http_oauth2: Implement stateless dynamic client registration Replaces previous explicit registration that required either the additional module mod_adhoc_oauth2_client or manually editing the database. That method was enough to have something to test with, but would not probably not scale easily. Dynamic client registration allows creating clients on the fly, which may be even easier in theory. In order to not allow basically unauthenticated writes to the database, we implement a stateless model here. per_host_key := HMAC(config -> oauth2_registration_key, hostname) client_id := JWT { client metadata } signed with per_host_key client_secret := HMAC(per_host_key, client_id) This should ensure everything we need to know is part of the client_id, allowing redirects etc to be validated, and the client_secret can be validated with only the client_id and the per_host_key. A nonce injected into the client_id JWT should ensure nobody can submit the same client metadata and retrieve the same client_secret

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labels:
summary: 'Test account credentials using HTTP'
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Introduction
------------

This module lets you test whether a set of credentials are valid,
using Prosody's configured authentication mechanism.

This is useful as an easy way to allow other (e.g. non-XMPP) applications
to authenticate users using their XMPP credentials.

Syntax
------

To test credentials, issue a simple GET request with HTTP basic auth:

    GET /auth_check HTTP/1.1
    Authorization: Basic <base64(jid:password)>

Prosody will return a 2xx code on success (user exists and credentials are
correct), or 401 if the credentials are invalid. Any other code may be returned
if there is a problem handling the request.

### Example usage

Here follows some example usage using `curl`.

    curl http://prosody.local:5280/auth_check -u user@example.com:secr1t