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

local method = {}
local method_mt = { __index = method }

-- This should return a set of supported mechanisms
function method:mechanisms()
	return {
		["OAUTH-SOMETHING"] = true;
	}
end

-- Called when a mechanism is selecetd
function method:select(mechanism)
	return mechanism == "OAUTH-SOMETHING";
end

-- Called for each message received
function method:process(message)
	-- parse the message
	if false then
		-- To send a SASL challenge:
		return "challenge", "respond-to-this";
	end

	if false then
		-- To fail, send:
		return "failure", "not-authorized", "Helpful error message here";
	end

	self.username = "someone";
	return "success";
end

local function new_sasl()
	return setmetatable({}, method_mt);
end

function method:clean_clone()
	return setmetatable({}, method_mt);
end

local provider = {}

function provider.get_sasl_handler()
	return new_sasl();
end

module:provides("auth", provider);